CHAPTER 2

RESEARCH FINDINGSThis chapter covers the findings obtained in the currentR&D program and summarizes the research as a whole. Detailed information on each part is given, along withdrawings and photographs, in Chapter 3 on in the CD-ROM version of this report.

A commercial scale ASR sorting, compaction, and solidification plant used to

obtain a grasp of the precision of sorting and the compaction and solidification

performance and to shed light on the problems in operation of the facility. Further,

the lead content and elution of lead from the sorted components and formed

product ASR were measured to assist in the operation of the facility by shredder

companies.

Compaction and solidification of ASR, which is now being disposed of in landfills,

is aimed at (1) extending the lifetime of controlled landfill site, (2) recovering

further metals from the residue, and (3) facilitating energy recycling. Further, this

technical development (sorting, compaction, and solidification) and dry distillation

and gasification are aimed at reducing the finally remaining ASR to 1/5 its volume

and 1/3 its weight. Figure 1.1 shows the flow of this equipments.

Further, Table 1.1 lists the findings obtained by this R&D program.

1.1. Development of Sorting, Compaction, and Solidification Equipment

1. Sorting, Compaction, and Solidification Technology

Fig. 1.1. System Flow of ASR Sorting, Compaction, and Solidification Plant

Nonferrous metal yard Glass, earth & sand yard

ASR input

(1) No. 1 Feeder

(2) Slant roller separator

Floating fraction

(7) Cyclone

(8) Magnetic separator

Residue for solidificationHeavy fraction

Intermediate fraction

(5) Eddy current separator

(6) Crusher

(3) Slant vibration separator

(4) Wind separator

Magnetics

Residue yard for solidification

(9) No. 2 Feeder

Smallerparticulates

Largerparticulates

Medium-sizeparticulates

Nonferrous metals

Magnetics under eddy current separator

Magnetics under magnet rolls

Light fraction

Formed product yard

(11) Compacter

Iron & Steel yard

Dry distillation/ gasification plant

(10) Slaked lime feeder

(12) Extruder

(13) Former

JAMA developed and commercialized a new extruder suitable for use for

processing ASR.

This extruder features:

(1) Mechanism suitable for processing ASR

(2) Prevention of clogging by use of single nozzle (improved maintenance)

(3) Further consideration and improvements for

Discharge capability increased about 77%

Power consumption per ton solidified ASR reduced about 32%

Time for raising temperature of solidified ASR (to 150°C) shortened about

44%

1.2. Development of ASR Extruder

Lead elution 0.16 to 0.30 mg/l (unprocessed)

< 0.08 mg/l (cement coating)Less than 0.3 mg/lGlass, earth & sand

The two-stage solidification system, compared with the one-stage solidification system, features a power consumption per ton solidified ASR reduced about 22%.

Comparison of one-stage solidification system and two-stage solidification system

The hydraulic drive system, compared with the electrical drive system, features:1) Power consumption of extruder per hour reduced about 26%2) Power consumption per ton solidified ASR reduced about 32%

Comparison of hydraulic drive system and electrical drive system

Cons

ider

ation

s and

impr

ovem

ents

for e

xtrud

er

Development of extruder for ASR (single-screw type twin-screw type)

Current average 1.6 ton/h (maximum 2.1 ton/h)3 ton/h discharge possible (estimated) with extruder power 260 kW (rated power: 400 kW)

Processing capability 3 ton/hSolidification capability

Less than 0.3 mg/l 0.09 to 0.26mg/lFormed product

Average 3.4 ton/h (maximum 3.6 ton/h)

Average 14.1 ton/h (maximum 18.0 ton/h)

9/10 (after sorting of metals and glass)

True specific gravity of formed product: 1.2 to 1.3 (use for land reclamation possible)

1/5 (apparent specific gravity of ASR/true specific gravity of formed product)

1/5 after dry distillationASR compacting ratio

1/3 after dry distillation

Processing capability 3 ton/h

Processing capability 10 ton/h

EvaluationResultsTarget

Compacting capability

Sorting capability

ASR weight reduction ratio

Item

Table 1.1. List of Findings in Sorting, Compaction, and Solidification Technology

Estimated

1) Prevention of clogging by use of single nozzle2) Discharge capability increased about 77%3) Power consumption per ton solidified ASR reduced about 32%4) Time for raising temperature of solidified ASR (to 150 C) shortened about 44%

Good

Good

Good

Good

Good

Good

Good

1.2.1. Comparative Evaluation of Single-Screw System and Twin-Screw System

JAMA compared and evaluated the single-screw system and twin-screw system

extruders in general use to determine which was suitable for processing ASR.

(1) The single-screw system is poor in engagement with the refuse, so the

twin-screw system was used.

(2) The twin-screw system, compared with the single-screw system, features:

Discharge capability increased about 77% (Table 1.2)

Power consumption per ton solidified ASR reduced about 32%

(Table 1.2)

Time for raising temperature of solidified ASR (to 150°C)

shortened about 44% (Fig. 1.2)

Note 1) Moisture content of ASR was 6.3% for both single-screw system and twin-screw system tests.Note 2) Figures show actual test values after 60 minutes after start of extruder.

Table 1.2. Comparison of Performance of Single-Screw and Twin-Screw Systems

57.3

1.445

172169

2850

84.7

0.836

Power per ton solidified ASR (kWh/ton)

Discharge of solidified ASR per hour (ton/h)

Twin-screw systemSingle-screw systemItem

Time for raising temperature of solidified ASR (to 150 C min)

Average temperature of solidified ASR ( C)

80

100

120

140

160

180

200

220

240

260

0 20 40 60 80 100 120 140 160

Single-screw system nozzle temperatureTwin-screw system nozzle temperatureSingle-screw system solidified ASR temperatureTwin-screw system solidified ASR temperature

Discharge time (minutes)

Fig. 1.2. Comparison of Nozzle Temperature and Solidified ASR Temperature in Single-Screw and Twin-Screw Extruders

Nozz

le an

d so

lidifi

ed A

SR te

mpe

ratu

re (

C)

Suitable temperature region when preparing solidified ASR (150 to 170 C)

Note) The upper limit of the suitable temperature region when preparing solidified ASR was made 170 C due to concerns over the production of hydrogen chloride gas.

1.2.2. Comparative Evaluation of Hydraulic Drive System and Electrical Drive

System

JAMA compared and evaluated the drive systems for extruders to determine the

difference in the power consumption in the case of use of a hydraulic motor and

the case of direct connection with an electrical drive system.

(1) The hydraulic drive system, compared with the electrical drive system,

features:

Power consumption of extruders per hour reduced about 26% (Fig. 1.3)

Power consumption per ton solidified ASR reduced about 32% (Fig. 1.4)

(2) A hydraulic extruders features a lower power consumption per ton

solidified ASR the greater the discharge, while the power consumption of

the electrical drive system is constant.

Disc

harg

e of s

olid

ified

ASR

per

hou

r (kg

/h)

Power consumption of extruder per hour (kWh)

Fig. 1.3. Relationship of Power Consumption of Extruder Per Hour and Discharge of Solidified ASR Per Hour in 400 kg/h Class Hydraulic System and Electrical Drive System Extruders (Screw Speed: 70 rpm)

90 122

0

100

200

300

400

500

600

0 20 40 60 80 100 120 140 160

Hydraulic systemElectrical drive system

Fig. 1.4. Relationship of Power Consumption Per Ton Solidified ASR and Discharge of Solidified ASR Per Hour in 400 kg/h Class Hydraulic System and Electrical Drive System Extruders (Screw Speed: 70 rpm)

Power consumption per ton solidified ASR (kWh/ton)

Disc

harg

e of s

olid

ified

ASR

per

hou

r (kg

/h)

0

100

200

300

400

500

600

0 100 200 300 400 500

Hydraulic systemElectrical drive system

203 300

1.2.3. Development of Single Nozzle for Prevention of Clogging

Most conventional extruders are of the type extruding the solidified ASR from

several nozzles. ASR features a large content of wires, so if such a type of

extruder is used, the wires will straddle the nozzles and successively entangle to

finally clog the nozzles (Fig. 1.5 shows example of clogging of compacter).

Therefore, the single-nozzle type was used to prevent clogging.

1.2.4. Comparative Evaluation of One-Stage Solidification System and Two-

Stage Solidification System

JAMA compared and evaluated two systems for solidification of ASR: the system

for solidification in one stage and a system for solidification of two stages of a

compacter and extruder.

(1) The two-stage solidification system, compared with the one-stage

solidification system, features a power consumption per ton solidified ASR

reduced about 22% (Table 1.3).

(2) If the electrical drive system compacter is changed to a hydraulic type, a

further reduction in the power consumption may be expected.

JAMA investigated and studied the technical knowhow required for operation of a

sorting, compaction, and solidification plant.

Fig. 1.5. Clogging of Compacter Nozzle (Nozzle Diameter ø50)

Table 1.3. Comparison of Performance of 3 ton/h class and 400 kg/h class Hydraulic Extruders

1661.292103 ton/h class extruder

213

Power consumption per ton solidified ASR

(kWh/ton)

0.40784

Discharge of solidified ASR per hour

(ton/h)

Power consumption of extruder per hour

(kWh)

400 kg/h class extruder

Item

Note) Both 3 ton/h class (n=11) and 400 kg/h class (n=9) are average values.

1.3. Optimal Operating Conditions

1.3.1. Conditions for Controlling ASR

To solidify ASR, it is particularly necessary to control the moisture. This is

explained below:

(1) Solidification of ASR requires that the moisture content be made less than

about 15% (Table 1.4).

(2) The goal is to reduce the moisture content of the ASR after discharge from

the compacter to not more than about 3% (Fig. 1.6).

(3) The following means may be considered for holding the residue in a dry state:

[1] Avoidance, as much as possible, of spraying of water when

shredding ELVs (but caution is required over ignition of ASR due

to sparks)

[2] Shielding of the ASR rain etc. during storage (by storage in yards

with roofs and doors)

(4) JAMA tried to dry about 8 tons of ASR (moisture content of about 24%,

height of pile of 2.8 m) by blowing air to the bottom of the receiving yard

of the facility, but the moisture content of the center portion fell to only

21% after 13 days and therefore this proved ineffective (air flow right after

discharge from fan: 13 m3/min, near yard entrance: 0.5 m3/min)

Moisture content of ASR (%)

Temperature setting of compacter

180 C (to )

200 C

Low (not more than 10%) Medium (about 15%) High (at least 20%)

Table 1.4. Moisture Content of ASR and Possibility of SolidificationEvaluation: (Pass) > (Fair) > (Fail)

(not solidified)

(not solidified)(to )

Note) The temperature setting of the extruder was made 240 C. For compacting, solidification, and forming, the temperature of the compacted ASR was made at least 135 C. The temperature of the solidified ASR has to be made at least 150 C.

Fig. 1.6. Relation Between Temperature of Compacted ASR Right After Discharge and Moisture Content of Original ASR

Moi

sture

cont

ent (

%)

0

5

10

15

20

25

30

0 20 40 60 80 100 120 140 160 180 200

Moisture content of original ASR (average)

13.2

6.4

24.6

16.8

15.2

8.9

7.0

2.7

Production of hydrogen chloride gas

Formable (solidifiable) region

Formable (solidifiable) region

Compacter 200 C, moisture content of original ASR : low(7.0%)

Compacter 200 C, moisture content of original ASR : medium(15.2%)

Compacter 200 C, moisture content of original ASR : high(24.6%)

Compacter 180 C, moisture content of original ASR : low(8.9%)

Compacter 180 C, moisture content of original ASR : medium(16.8%)

Temperature of compacted ASR ( C)

1.3.2. Optimal Operating Conditions of Sorting Equipment

JAMA studied the slant angle, roller speed, and air flow for sending the ASR

upward in slant roller separator, the air speed in separator nos. 1 to 3 in the wind

separators, and distance to the conveyor in magnetic separators, and the belt

speed and angle of the partitions 1, 2 in eddy current separators. The optimal

conditions are shown in Table 1.5.

1.3.3. Optimal Operating Conditions of Compacter and Extruder

JAMA studied the temperature settings of the nozzles of the compacter and

extruder, the actual temperatures of the nozzles, and the temperatures of the ASR

immediately after discharge from the nozzles. Table 1.6 shows the optimal

operating conditions of a compacter and extruder when compacting and

solidifying ASR with different moisture contents.

Table 1.5. Optimal Operating Conditions of Sorting Equipment

Name of apparatus Optimal operating conditions

Distance between magnetic separator and conveyor 300mm(250 to 385mm)

Partition 1 angle ; -30˚Partition 2 angle ; 0˚ to 30˚

Eddy current separator Belt speed

Wind separators (nos. 1, 2, and 3) Air speed: No. 1 and No. 2: 13 m/s, No. 3: 12 m/s (4 to 18 m/s)

Slant roller separator

Partition 1 angle ; -30˚ to 0˚Partition 2 angle ; 0˚ to 30˚

80 to 100m/min

60m/min

Slant angle: 35 C (32 C to 39 C)Roller speed: 190 rpm (65 to 310 rpm)ASR feeding air speed: 2.3 to 10.3 m/s

Note 1) Figures in parentheses in the table show the ranges studied. Note 2) No difference was seen with an ASR feeding air speed of the slant roller separator in the range studied (2.3 to 10.3 m/s).Note 3) The range studied of the belt speed of the eddy current separator was 40 to 100 m/s and the range studied of the partitions was -30 C to 30 C.

Table 1.6. Optimal Operating Conditions of Compacter and Extruder

Moisture content of ASR (%) Compacter Extruder

Low (not more than 10%)

Medium (about 15%)

High (at least 20%)

Nozzle temperature setting:180 to 200 CNozzle actual temperature:180 to 200 CTemperature of compacted ASR:135 to 170 C

Nozzle temperature setting:240 CNozzle actual temperature:180 to 240 CTemperature of solidified ASR:150 to 170 C

Nozzle temperature setting:240 CNozzle actual temperature:190 to 240 CTemperature of solidified ASR:150 to 170 C

Nozzle temperature setting:200 CNozzle actual temperature:200 CTemperature of compacted ASR:135 to 170 C

Under conditions of a nozzle temperature setting of the compacter of 200 C and of the extruder of 240 C, the solidified ASR formed flakes and could not be formed.

Note 1) Nozzle of compacter: 50, thickness of liner: 41 mm, nozzle of extruder: 110.Note 2) The upper limit temperatures of the compacted ASR and solidified ASR were made 170 C due to concerns over the production of hydrogen chloride gas.

JAMA investigated the effects of fine crushing of ASR on the sorting precision.

(1) The yield of glass, earth and sand in the ASR differed according to the

differences in the shredder companies.

(2) Even the same shredder company had different yields of glass, earth and

sand depending on the lot.

(3) Fine crushing of the ASR resulted in an increase in the glass powder and

its subsequent dispersal or spread to other yards and therefore a drop in

the yield of glass, earth and sand (Fig. 1.7). Accordingly, and also

considering the wear of the screw blades of the compacter and extruder

in the solidification process, fine crushing is not desirable.

1.4. Crush Conditions and Yield of Glass

ASR contains unrecovered aluminum. This can be recovered by installation of an

eddy current separator. JAMA investigated the investment effect.

The cost of an eddy current separator can be recovered in seven years assuming

a yield of aluminum of at least 0.27% even for a separator of the least profitable

ASR processing rate of 3.3 ton/h, case 1, and a single shift and assuming a yield

of aluminum of at least 0.04% for a separator of the most profitable rate of 10 ton/h

and 3 shifts in both case 1 and case 2 (Table 1.7).

1.5. Costs of Eddy Current Separators and Standards for Aluminum Recovery Rate

Fig. 1.7. Crushing Conditions and Yield of Glass, Earth & Sand in ASR of Shredder Company A and Company B (Ordinary Sorting and Fine Crushing)

0

5

10

15

0

5Sorti

ng ra

te (%

) 10

15

0.41.2

0.70.1

6.7

1.50.5 0.60.2

3.3

0.91

0.60.11.3

2.2

0.90.8

0.3

6.4

Iron & steel(iron & steel yard)

Iron & steel(under magnet roll)

Iron & steel(under eddy current separator)

Nonferrous metal yard

Glass, earth & sand yard

90.9 93.9 96.189.4

ASR for solidification (%)

Company BCompany ALot 1

Company BLot 2

Company BLot 2

Fine crushing

Table 1.7. Standards for Recovery Rate of Aluminum in Eddy Current Separators

ASR processing rate (ton/h) 3.3 6.7 10

Note 1) The cost of an eddy current separator can be recovered in seven years assuming a rate of recovery of aluminum of over the figure given in the table. Note 2) Case 1 is use of a 250 kW class electrical compacter and a 400 kW class hydraulic extruder, while case 2 is use of 250 kW class and 400 kW class hydraulic extruders. One shift equals 8 hours operation, but the three shifts in case 1 means 20 hours operation. Note 3) The cost of an eddy current separator is 7 million yen for one with a processing rate of 3.3 ton/h, 8.3 million yen for one with a processing rate of 6.7 ton/h, and 9.3 million yen for one with a processing rate of 10 ton/h. The 1.5 million yen reduction in cost by consolidation and scrapping of belt conveyors is also considered.

1 shift 0.27 0.15 0.11Standard of recovery rate of aluminum 2 shift 0.13 0.08 0.06

3 shift 0.11 0.09 0.06 0.05 0.04 0.04

Solidification process Case 1 Case 2 Case 1 Case 2 Case 1 Case 2

There are currently two types of mesh size of slant vibration separator (three types

for sorted component). JAMA studied the optimal mesh size for recovery of the

glass in ASR and the possibility of reduction of the types of meshes.

(1) Slant vibration separator currently separate ASR into three sizes of less

than 5 mm, 5 to 10 mm, and more than 10 mm. The 5 to 10 mm fraction

(medium-size particulates) contains 45% glass, while the more than 10

mm fraction (larger particulates) contains only about 0.9% glass.

Therefore, it is possible to reduce the types of mesh sizes to two: one

above and one below 10 mm (Table 1.8 and Fig. 1.8).

(2) Reducing the types of mesh sizes makes it possible to reduce the number

of cyclones and wind separator fans etc.

1.6. Mesh Size of Screens of Slant Vibration Separator Designed for Recovery of Glass in ASR

3760.00

299.37

15.08

61.03

00

68.68

181.61

41.81

20.39

332.79

71.42

OtherGlass OtherGlass

More than 5 mm screenLess than 5 mm screenItem

Larger particulates (more than 10 mm) weight (g)

Medium-size particulates (5 to 10 mm) weight (g)

Smaller particulates (less than 5 mm) weight (g)

Table 1.8. Weight of Glass and Other Components in Smaller, Medium-size and Larger Particulates Above and Below 5 mm Screen

Note) The smaller particulates, medium-size particulates and larger particulates were sampled separately. There is no relation among the weights of the particulates.

Smaller particulates Medium-sizeparticulates

Largerparticulates

0

10

20

30

40

50

60

70

Glas

s con

tent (

%)

63.1

45

0.92

Mesh (mm) of slant vibration separator

x < 5 5 < x < 10 10 < x

Fig. 1.8. Glass Content of Smaller Particulates, Medium-size Particulates, and Larger Particulates

(1) Sorting of the wire from the ASR is difficult (ASR is cottony in form and

wire is entangled in it).

(2) About 100% of the wire harness (copper shown in Fig. 1.9) in particular is

mixed in the ASR for solidification.

1.7. Sorting of Wire From ASR

(1) The ratio of compacting of the ASR after solidification and forming was

1/5 (apparent specific gravity of original ASR/true specific gravity of

formed product)

(2) The true specific gravity of the formed product is about 1.2 to 1.3. Use for

land reclamation is possible.

1.8. Effect of Compacting of ASR

1.9.1. Prevention of Elution of Lead From Formed Product

(1) There was 0.09 to 0.26 mg/l elution of lead from the formed product.

Compacting and solidification result in a value satisfying the standard for

disposal at landfills (Fig. 1.10, ASR of Shredder Company B).

(2) This assumes, however, that intermixture of parts using lead (batteries, fuel

tanks, etc.) into ASR at the time of dismantling of the automobiles is avoided.

1.9. Effect of Prevention of Elution of Lead

Fig. 1.9. Rates of Distribution of Iron & Steel, Aluminum, and Copper inYards in ASR of Shredder Company A and Company B (Ordinary Sorting and Fine Crushed)

Fine crushing

CompanyB

CompanyB

CompanyA

Lot 1Lot 2

Fine crushing

CompanyB

CompanyB

CompanyA

Lot 1Lot 2

Fine crushing

CompanyB

CompanyB

CompanyA

Lot 1Lot 2

Iron & Steel Aluminum Copper

0

20

40

60

80

100

0

20

40

60

80

100

12.6

47.1

25.2

15.1

33.6

41.8

20

4.6

50.9

21.8

16.5

10.8

11.1

88.9

22.2

77.8

35.3

64.7

2.6

97.4 100

0.7

99.3

Iron & steel(iron & steel yard)

Iron & steel(under magnet roll)

Iron & steel(under eddy current separator)

Nonferrous metal yard

Yard for ASR for solidification

Rate

of d

istrib

utio

n (%

)

00

0.5

1

1.5

2

2.5

3

Lead

elut

ion

(mg/

l)

A-1

A-12

A-2

A-3

B-11

B-12

B-2

Fig. 1.10. Elution of Lead From Original ASR, Sorted Components, and Formed product in Different Lots of Shredder Company A and Company B (n=2 average)

Original ASR Glass, Earth & Sand ASR for solidification Formed product

1.72

0.99

0.55

1.42

0.7

0.380.58

2.6

0.80.86

0.5

0.120.26

0.09

0.260.23

<0.02

1.9.2. Prevention of Elution of Lead From Glass, Earth & Sand (Effect of Addition

of Cement)

(1) The elution of lead from the glass, earth & sand was 0.16 to 0.30 mg/l in

the case of unprocessed glass, earth & sand and 0.08 mg/l, below the

limit of detection, in the case of cement coating. That is, cement coating

enables disposal at landfills (Fig. 1.11, ASR of Company B).

(2) This assumes, however, that intermixture of parts using lead (batteries, fuel

tanks, etc.) into ASR at the time of dismantling of the automobiles is avoided.

1.10.1. Size of ASR Receiving Yard

The ASR receiving yard, considering entry by 10-ton dump trucks, must have as

minimum dimensions an effective gate opening of 3.5 m, height of 6 m, and depth

of 7 m (currently W 2.8m x H 5m x L 5m ).

1.10.2. Installation of Sprinkler System

The ASR receiving yard and formed product storage yard must be provided with

temperature monitoring (alarm) and sprinkler systems to deal with spontaneous

ignition.

1.10.3. Crusher at Time of Operation

If ASR piles up around the hammer of the crusher at the time of operation of the

sorting equipment, it may be ignited by the sparks caused by the hammer

portion. Therefore, the following measures have to be taken:

[1] Frequent clearing of ASR deposited near hammer

[2] Removal of steel tires and other difficult to crush materials (in particular in

the case of steel tires, the hammer will continue striking the steel cord if

1.10. Points to Note When Designing Plants

Fig. 1.11. Effect of Prevention of Elution of Lead From Glass, Earth & Sand

Original ASR Formed product Glass, earth & sandunprocessed

Glass, earth & sandtreatment by K-20

Glass, earth & sand cement coating

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

1.42

0.090.23

0.08 0.08

Elut

ion

of le

ad (m

g/l)

1.06

1.77

0.08 0.09

0.3

0.160.08 0.08 0.08 0.08

n=1

n=2

Average

Note 1) The lower limit of content of lead is 0.08 mg/l. The figure in the table was made 0.08.

Note 2) K-20: metal silica forming agent

not crushing it and sparks will be produced).

1.10.4. Cooling of Formed Product

The solidified and formed product, which has been heated to about 180˚C, has to

be sufficiently cooled by immersion in water or by forced sprinkling etc.

The newspapers and other media have reported incidents of spontaneous ignition

of piles of ASR. There has been almost no theoretical analysis or demonstration

studies conducted to throw light on this phenomenon. To prevent fires from

starting, it is necessary to clarify the causes and establish technology for

preventing spontaneous ignition.

In this study, JAMA conducted tests on the heat generation of the solidified ASR

shown below (section 2.2), analyzed the composition of the gas produced, and

studied the (1) self heat generation, (2) danger of spontaneous ignition, and (3)

method of management for prevention of fires for piles of solidified ASR.

To elucidate the phenomenon of spontaneous ignition of piles of solidified ASR

and throw light on technology for prevention of fires.

(1) Test of Heat Generation of Solidified ASR

1) Test of Heat Generation by Heat Insulating Containers

To investigate the heat generation of piles of solidified ASR,

solidified ASR of different temperatures were placed in heat

insulating containers (volume about 1m3) and the temperature

behavior inside the ASR was examined.

2) Test of Heat Generation by Heating Furnace

The heat generation inside ASR when making the outside ambient

temperature of solidified ASR in small piles constant by a heating

furnace was investigated using the height of the ASR piles as a

parameter. From the results and analysis, JAMA predicted the

relationship between the pile height and temperature of

spontaneous ignition when storing ASR in large piles.

(2) Analysis of Composition of Gas Produced From Solidified ASR

JAMA analyzed the composition of the gas produced as follows for mainly

2.1. Object

2.2. Study

2. Spontaneous Ignition

the flammable gases to study the danger of spontaneous ignition when

piling up solidified ASR:

[1] Analysis of composition of gas produced by samples of small

amounts of solidified ASR

[2] Analysis of composition of gas produced by solidified ASR piled

up in stockyard

[3] Analysis of composition of gas produced by solidified ASR

generating heat using heat insulating containers

(3) Test of Cooling of Solidified ASR

JAMA conducted a cooling test(*), changing various conditions, while

changing the size and shape of the ASR so as to study the best approach

to cooling ASR in order to ensure safety from fire.

(*): Current cooling test (cooling test of cooling apparatus attached to

compacting/solidification demonstration test facility), cooling test by air,

sprinkling, water (standing water and flowing water), etc.

(4) Others

Thermal analysis of differential heat etc.

Main items measured:

• Measurement by TG-DTA and DSC

• Heat conductivity

• Measurement of specific heat etc.

(1) Heat Generation of Solidified ASR and Phenomenon of Spontaneous

Ignition

1) According to the results of the heat generation test, it was found

that ASR has self heat generation, has an extremely high

heatstorage, and self ignites at a relatively low temperature (about

150°C).

2) The heat generating reaction in this low temperature region is

believed to be due to the "oxidation dehydrogenation reaction".

3) Further, it was found that the self-heat generation reaction is

rapidly promoted when the ASR temperature reaches about 200°C

and finally spontaneous ignition inevitably occurs.

4) On the other hand, according to the results of the analysis of the

composition of the gas produced, a considerably high con-

centration (level close to explosive limit) of hydrogen gas was

detected when the ASR temperature reached over about 230˚C.

5) From the above, it is believed that spontaneous ignition occurs

due to the rise in the internal temperature due to the self-heat

generation accompanying the oxidation reaction of the ASR and

the ignition of the ASR due to this heat and the ignition of the gas

produced inside.

2.3. Findings

(2) Danger of Ignition of Deposited Solidified ASR

1) Figure 2.1 shows the relation between the height of piles of ASR

and the limit ignition temperature according to the findings of the

heat generation test.

2) Prevention of spontaneous ignition requires cooling to an ASR

temperature of about 80°C assuming a height of the ASR pile of 3

m.

3) Further, with a pile height of 7 to 8 m, spontaneous ignition will

probably occur at a temperature somewhat higher than the

outside air temperature.

4) Suggestions are given in Section 6 of Chapter 3.2 of this report

(CD-ROM version) on the best approach to cooling heated

solidified ASR to a certain temperature in a certain time.

(3) Fire Prevention Measures

To prevent spontaneous ignition of piles of solidified ASR,

1) It is necessary to reduce the height of the ASR pile and ASR

temperature to below certain levels.

- It is necessary to cool the ASR to a temperature of a level of

80°C assuming a pile of a height of 3 m.

- It is necessary to cool the ASR by immersion in water or forced

sprinkling etc. when piling up heated and solidified ASR.

2) It is desirable to constantly monitor the internal temperature of the ASR

when piling up a large amount of ASR such as at intermediate treatment

sites or final controlled landfill sites.

In this study, JAMA examined the heat generation of solidified ASR and measures

for preventing fires. Even pre-solidified ASR, however, harbors the same danger of

spontaneous ignition like solidified ASR according to the results of predictions of

the temperature of spontaneous ignition. Considering the fact that intermediate

Spontaneous ignition region

Convergence or steady state region

Height of ASR Pile(m)

(**)

0 0 1 2 3 4 5

50

100

150

200

250

Predicted values according to Semenov and Frank-Kamenetski heat ignition theory

(**): The "limit ignition temperature" given here means the lowest value of the "outside ambient temperature" causing spontaneous ignition.

Fig. 2.1. Relation Between Height of Piles of ASR and Limit Ignition Temperature (Predicted)

Lim

it ig

nitio

n tem

pera

ture

( C)

2.4. Future Issues

treatment facilities and final controlled landfill sites do not constantly monitor the

temperature of the piles of ASR, the danger of spontaneous ignition is extremely

high. Pre-solidified ASR is not cooled by water since the sorting and solidification

performance would fall, so the question is how to efficiently disperse the internally

stored heat.

Aside from spontaneous ignition, there is also a danger of ignition by sparks

produced by the crusher or the heat of friction of belt conveyors. Continued care

will be required in the future during operation of facilities.

(According to the findings of a survey by the Tokyo Firefighting Agency on fires in

intermediate waste treatment facilities (***), sparks from crushers have been

judged responsible for most fires.)

(***: Survey Section, Prevention Department, Tokyo Firefighting Agency, "Fires in

Intermediate Waste Treatment Facilities", Fire (no. 225), vol. 46, no. 6, December

1996.

JAMA has been working to develop technology for recovery of heat based on the

dry distillation for recycling the ASR of ELVs. This apparatus dry distills and

gasifies the ASR and recycles the flammable gas in the dry distillation gas.

Further, the dry distillation residue is refined to recover the metal resources. The

carbon is recycled as steelmaking materials.

The apparatus is a batch type, high temperature gas type dry distillation and

gasification system and features, compared with other apparatuses (gasification

and melting, oil-producing apparatuses, etc.), a simpler structure, easier

operation, a smaller capital investment, and a suitability for small-sized, dispersed

apparatuses. The flow of the system is shown in Fig. 3.1.

[Summary of System]

• This plant system, as shown in Fig. 3.1, is comprised mainly of an air heating

furnace, dry distillation furnace, and secondary incineration furnace.

• The air heating furnace uses LPG as fuel and has an inner wall comprised by

refractories and insulating materials. It is constructed so that the heat loss of the

furnace proper is sufficient small compared with the heat generated by

combustion inside it.

• The RDFed ASR is charged into special cages which are placed in the dry

distillation furnace stacked three high. (The shape and composition of RDFed

ASR are given in the next section.)

Fig. 3.1. System Flow of Dry Distillation and Gasification Apparatus

3.1. Development of Dry Distillation and Gasification Apparatus

3. Dry Distillation and Gasification

• The ASR is heated by the 1000°C level high temperature inert gas blown in from

the air heating furnace and converted to fuel gas comprised mainly of methane.

• The thermally decomposed gas produced from the ASR and the unburned

carbon are incinerated in the secondary incineration furnace at a high

temperature (1200 to 1300°C) to detoxify them.

• Note that this apparatus is an experimental system, so the thermally

decomposed gas is simply burned in the secondary incineration furnace. In the

overall process, there would be thermal recycling using this gas as a heat

source.

[Shape and Composition of Solidified ASR]

(1) Shape

The solidified ASR tested, as shown in Fig. 3.2, is made flat in shape

overall with wavy projections on the surface so as to promote heat

contact.

The unit specific gravity is about 1.2 g/cm3, while the bulk specific gravity

is about 0.4 to 0.5 g/cm3.

(2) Composition

The ASR is comprised of 50 to 60% volatile matter, about 10% fixed

carbon, about 30% ash, and 2 to 3% moisture. The high generation is

about 25.1 MJ per unit weight.

Note that shredder residue 100% from automobiles was used for the

experiment.

200 - 30020

150

[Shape]

[Composition]

Volatile matter

Fixed carbon

Ash

Moisture

55%

10%

32%

3%

Fig. 3.2. Shape and Composition of Solidified ASR

•

•

•

•

[Configuration of Dry Distillation and Gasification Apparatus]

• The combustability of the dry distillation gas was examined in two cases, the case of

cooling of the dry distillation gas by a condenser and removal of the moisture etc.

and the case of direct combustion, to study the best configuration of the dry

distillation and gasification apparatus. As a result, it was learned that self-

combustion of the dry distillation gas can be secured even without a condenser.

Therefore, in the development of the demonstration system, JAMA decided to use a

condenser-less system not requiring treatment of the condensed oil and water.

• Examples of the concentrations of dioxins in the two systems are shown in Fig.

3.3 and Fig. 3.4.

[Findings Obtained]

• If condensing the oil and water in the dry distillation gas by a condenser, the

concentration of dioxins in the oil and water becomes considerably high

(condensed water: 1.89 ng-TEQ/l, condensed oil: 51 ng-TEQ/l) and treatment to

detoxify the oil and water is newly required (Fig. 3.3).

• Therefore, JAMA experimented with high temperature incineration directly in a

secondary incineration furnace without passing the dry distillation gas through a

condenser (Fig. 3.4).

• As a result, it was confirmed that while the self-combustion of the dry distillation

gas in the secondary incineration furnace falls somewhat, the dioxins in the dry

distillation gas can be substantially completely broken down.

Fig. 3.3. Concentration of Dioxins in Condensed Oil and Water in Condenser System

Fig. 3.4. Concentration of Dioxins in Exhaust Gas of Combustion in Condenser-less System

Dry distillation furnace

High temperature furnace

Dry distillation furnace

High temperature furnace

Secondary incineration furnace

Secondary incineration furnace

Condenser

Concentration of dioxins•Condensed water: 1.89 ng-TEQ/L•Condensed oil: 51 ng-TEQ/g

Concentration of dioxins in exhaust gas < 0.1ng-TEQ/Nm3

• The dioxins, particulate matter, and concentration of metals at the smokestack

outlet of the secondary incineration furnace were analyzed for the two systems

and the results compared. As a result, no significant difference was observed.

• JAMA investigated the thermal decomposition of ASR at the time of dry distillation

from various perspectives. It found that ASR contains various substances, but

exhibits somewhat stable trends in its thermal decomposition properties. The

optimum temperature in dry distillation was found to be at the level of 500°C.

• Examples of the thermal decomposition properties found from the investigations

are shown in Fig. 3.5 to Fig. 3.8.

[Findings Obtained]

• At the time of dry distillation, the ASR is melted, evaporated, thermally

decomposed, crystallized, and oxidized and subjected to other reactions.

These reactions, however, substantially are completed in the process of the rise

in temperature to the 500°C level.

• That is, ensuring that the ASR reaches a temperature of the 500°C level is an

important point in increasing the dry distillation yield.

3.2. Survey of Temperature Conditions of Dry Distillation of Solidified ASR

0102030405060708090

100

200 300 400 500 600 700 800 900 1000

Average temperature of ASR ( C)

Fig. 3.5. Relation of Average Temperature of ASR and Weight Loss on Heating

Weig

ht lo

ss o

n he

ating

(%)

Fig. 3.6. Relation of Hysteresis Temperature of ASR and Volatile Components

0

10

20

30

40

50

60

70

80

0 100 200 300 400 500 600 700 800 900 1000

Volat

ile co

mpo

nent

s (w%

)

Volatile components of ASR before dry distillation: 55 to 60%

Before dry distillation: 68 to 77%

Fig. 3.7. Relation of Hysteresis Temperature of ASR and Ig-Loss

0

10

20

30

40

50

60

70

80

0 100 200 300 400 500 600 700 800 900

Ig-L

oss (

%)

O2 concentration in high temperature gas:2% O2 concentration in high temperature gas:4%

Rate of addition of Ca(OH)2 :1.2%

Fig. 3.8. Relation of Hysteresis Temperature of ASR and Heat Generation

0

10

20

30

40

0 200 400 600 800 1000

High heat generation of ASR before dry distillation: 25.94 MJ

Heat

gene

ratio

n of

flam

mab

le co

mpo

nent

s of A

SR (M

J)

H : 15.5 MJ

Hysteresis temperature of ASR ( C)

Hysteresis temperature of ASR ( C) Hysteresis temperature of ASR ( C)

• Further, as shown in Fig. 3.8, if the ASR reaches a temperature of over 500°C, it

is possible to relatively stably recover about 15.5 MJ (3,700 kcal) of heat per

unit weight.

[Relation of Hysteresis Temperature of ASR and Degree of Dry Distillation]

• The relation between the hysteresis temperature of ASR and the degree of dry

distillation as found from the results of the thermal decomposition properties of

ASR is shown in Fig. 3.9.

• As illustrated, if the hysteresis temperature of ASR reaches the 500°C level,

almost all of the volatile components in the ASR are released and the degree of

dry distillation reaches the 100% level.

• The relation between the hysteresis temperature of ASR and the degree of dry

distillation up until reaching 500°C can be approximated by the polynomial

shown in the figure, where the degree of dry distillation is Gf and the hysteresis

temperature of the ASR is Td.

[Dry Distillation and Gasification by Conventional System (High Temperature Gas

Ascending Flow)]

• If, at the same time as measures for soaking in the dry distillation furnace

(measures for heat conduction of ASR), the concentration of oxygen in the high

temperature gas is made a certain degree higher (to about 5%) to promote the

partial oxidation of the ASR, recovery of about five times the heat energy as the

external input heat is possible and the initial target of (input heat x 5) can be

substantially achieved.

0

20

40

60

80

100

120

200 400 600 800

Degr

ee o

f dry

dist

illati

on (%

)

Hysteresis temperature of ASR ( C)

Fig. 3.9. Relation of Hysteresis Temperature of ASR and Degree of Dry Distillation

+

3.3. Effect of Thermal Recycling (Energy Recovery Input Calories x 5)

• Fig. 3.10 plots the relation between the externally input heat energy and the rate

of recovery of heat energy using valid experiments. Case 5 is a test where the

concentration of oxygen in the high temperature gas was raised to 3 to 5%

(ordinary level <1.0%) and the feed of ASR to the lowest cage in the dry

distillation furnace was increased. In the case of a 5% concentration of oxygen,

the amount of heat energy recovered rises 4.7 to 5.5-fold.

[Findings Obtained]

• To increase the amount of heat energy recovered, it is effective to raise the

concentration of oxygen in the high temperature ASR by a certain degree to

promote the partial oxidation of the ASR and to raise the rate of temperature rise

of the ASR.

• Further, the high temperature gas for heating the ASR is sucked in from the

bottom of the dry distillation furnace, so it is important to increase the amount of

ASR fed to the bottom of the dry distillation furnace and, simultaneously, to

establish a laminar flow of high temperature gas in the dry distillation furnace

and equalize the temperature in the furnace.

• Regarding how far to raise the concentration of oxygen in the high temperature

gas, judging from the state of deposition of soot in the piping and the decline in

the purity of copper in the ASR, 5% or less is believed appropriate.

[Dry Distillation and Gasification by High Temperature Gas Descending Flow]

• In the dry distillation of the conventional ascending flow system, the high

temperature gas flows unevenly in the dry distillation furnace. There is a

considerable difference in the degree of dry distillation depending on the

location of the ASR. This reduced the efficiency of recovery of the heat energy.

When considering the reduction of the costs for commercial technology, the

efficiency of recovery of the heat energy has to be improved more.

00

1

2

3

4

5

6

7

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Input heat per unit weight ASR and unit time (MJ/kgh)

Fig. 3.10. Relation of Input Heat and Amount of Heat Energy Recovered

Ratio

of r

ecov

ery o

f hea

t ene

rgy (

X)

O2 : 5%O2 : 3%

Case 1

Case 2

Case 3

Case 4

Case 5

Case 1

Case 5

Case 2 to 4

• Therefore, JAMA modified part of the demonstration plant and, as shown in Fig.

3.11, experimented with making the flow of the high temperature gas to the dry

distillation furnace a descending flow. It then compared the results with the

results of the conventional ascending flow system.

• The conditions of the experiment were a concentration of oxygen in the high

temperature gas of <1.0% in the case of the descending flow and 4.4% in the

case of the ascending flow and the provision or omission of a rectifying pipe.

Otherwise, the amount of the ASR fed to the dry distillation furnace, the amount

of heat of the flow of high temperature gas, etc. were substantially the same in

the two systems.

[Findings Obtained]

[1] Equalization of heat in furnace: Looking at the temperature of the ASR in

the same cage, as shown in Fig. 3.12, the difference due to location was

clearly smaller in the case of the descending flow system. The heat was

made considerably uniform in the furnace.

[2] Rate of temperature rise of ASR (temperature gradient): The rate of

temperature rise of the ASR during the dry distillation, as shown in Fig.

3.12, was improved about 20% in the descending flow system.

132.1/112.9/95.6/108.2

12,899 MJ 13,602 MJ

4.16 times 4.55 times

Average 94.7% Average 99.8%

Descending flow system

6.5Hr 6.6 Hr

Ascending flow system

Table 3.1. Main Findings in Two Systems

Dry distillation time

ASR dry distillation degree

Recovered heat

Ratio of recovery of heat energy

ASR temperature gradient (upper stage/middle stage/lower stage/overall) C/H 69.5/87.7/100.0/87.7

3.52MJ/kg

Fig. 3.11. Concept of Experiment

(Dry distillation experiment by descending flow system)(Dry distillation experiment by conventional ascending flow system)

3.39MJ/kg

Temperature measurementFive locations in each cage

Temperature measurement(5 locations)

Five locations in each cage

Dry distillation gas

Dry distillation gas

Solidified ASR Solidified ASR

Solidified ASR

Dry distillation furnace Dry distillation furnace

High temperature gas

High temperature gas

High temperature gas

Temperature measurementMiddle stage

Upper stage

Lower stage

ASR cages

Middle stage

Upper stage

Lower stage

ASR cages

200 rectifying pipe(3 each at middle and lower stages)

(1)

(4)(5)

(3)(2)

Conduction of heat to the ASR was observed to have been promoted.

[3] Efficiency of recovery of heat energy: The ratio of recovery of heat energy

in the same dry distillation time, as shown in Table 3.1, was increased

about 10% in the descending flow system (4.55). This is not that large as

a ratio of recovery, but the findings were the result of just one example.

Depending on the conditions, the ratio of recovery could probably be

increased more.

Temperature of ASR at different parts of lower stage cage

0

100

200

300

400

500

600

700

800

900

1000 1000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 11 12 13 14 15

Temperature of ASR at different parts of upper stage cage

[High temperature gas, ascending flow] [High temperature gas, descending flow]

Fig. 3.12. Temperature of ASR in Same Cage and Comparison of Rate of Temperature Rise of ASR at Different Locations

0

50

100

150

200

Rate

of te

mpe

ratu

re ri

se o

f ASR

( C/

h)

Ascending flow system dry distillation

Descending flow system dry distillation

Ascending flow system dry distillation Upper stage Middle stage Lower stage

Lower stage Middle stage Upper stageDescending flow system dry distillation

ASR position

(1)(2)(3)(4)(5)

Average

(1)(2)(3)(4)(5)

Average

0

100

200

300

400

500

600

700

800

900

0 1 2 3 4 5 6 7 8 9 10

Tem

pera

ture

of A

SR (

C)

Tem

pera

ture

of A

SR (

C)

Time (hour) Time (hour)

3.4.2. Concentration of Dioxins in Dry Distillation Residue

• If the ASR reaches a temperature over about 400°C during the dry distillation,

the concentration of dioxins in the residue is reduced to a level sufficiently

satisfying the soil standards of the countries of Europe (standards for athletic

fields and residential land: less than 0.1 to 2 ng-TEQ/g). (In all of the 21

examples where the hysteresis temperature of the ASR reached over 380°C, the

concentration was below 0.075 ng-TEQ/g.)

• Twenty-three samples of dry distillation residue obtained under different

experiment conditions were analyzed. The results are shown in Fig. 3.14.

Fig. 3.13. Concentration of Dioxins in Exhaust Gas of Combustion

0

1

2

3

4

5

0 3

Conc

entra

tion

of d

ioxin

s (ng

-TEQ

/Nm

3 )

After adjustment of secondary incineration furnace (N=5)0.0017 to 0.115ng-TEQ/Nm3

Before adjustment of secondary incineration furnace (N=4)0.71 to 1.8ng-TEQ/Nm3

Prescribed value:5ng-TEQ/Nm3

T1 T2

3.4.1. Concentration of Dioxins in Exhaust Gas of Combustion

• The dry distillation gas obtained by this dry distillation and gasification

apparatus has an extremely low concentration of particulate matter and an

excellent combustability. Therefore, it is possible to burn it at a high temperature

of over 1200°C even with an ordinary secondary combustion apparatus. In that

sense, this apparatus is effective against dioxins.

• So long as the combustion in the secondary incineration furnace is stabilized,

the concentration of dioxins is at a level of less than 0.1 ng-TEQ/Nm3 in both the

Nos. 1 and 2 furnaces (Fig. 3.13).

• To stabilize the combustion, maintenance of the concentration of oxygen within

a certain range and maintenance of the concentration of CO in the exhaust gas

at a low level (less than 5 ppm) are important.

3.4. Concentration of Dioxins

[Findings Obtained]

• The concentration of dioxins in the dry distillation residue was found to be not

that much related to the concentration of oxygen in the high temperature gas or

the rate of addition of Ca(OH)2 to the ASR. Rather, there is some dependency on

the hysteresis temperature of the ASR.

(Amount of variation of O2 and Ca(OH)2 in the experiments Concentration of

oxygen: <1.0 to 7.0%, rate of addition of Ca(OH)2: 0 to 4.5%.)

• The results of the analysis were compared with the incineration ash (*) and fly

ash (**) of municipal garbage. The level was clearly lower.

((*): 0 to 0.5 ng-TEQ/g, (**): 1 to 50 ng-TEQ/g)

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0 100 200 300 400 500 600 700 800 900 1000

Solidified ASR Temp. ( C)

O2 : < 1.0 %, Ca(OH)2 : 0%

O2 : < 1.0 %, Ca(OH)2 : 1.2%

O2 : < 1.0 %, Ca(OH)2 : 2.4%

O2 : 3.0%, Ca(OH)2 : 2.4%

O2 : 4.4 %, Ca(OH)2 : 0%

O2 : 4.0 %, Ca(OH)2 : 1.2%

O2 : 4.4 %, Ca(OH)2 : 4.5%

O2 : 5.0%, Ca(OH)2 : 2.4%

O2 : 7.0 %, Ca(OH)2 : 2.4%

Fig. 3.14. Concentration of Dioxins in Dry Distillation Residue (No. of Samples N = 23)

Conc

entra

tion

(ng-

TEQ/

g)

Concentration of Dioxins and Soil Standards in Different Countries

Farmland Athletic fields Residential land

Netherlands 1.0 1.0 1.0

Germany 0.04 0.1 1.0**

Sweden 2.0

**: Standard for urban areas. 2.0 for industrial areas(Source: Preprints of 23rd Symposium of Japan Society of Environmental Chemistry)

Soil standard(ng-TEQ/g)

3.5.1. Total Balance of Chlorine

• ASR contains PVC. Thermal decomposition of PVC produces hydrogen chloride.

One of the features of this apparatus is the ability to treat 93 to 96% of the

chlorine in the ASR at the dry distillation stage.

• Test calculations show that almost all (93 to 96%) of the chlorine in the ASR

3.5. Treatment of Chlorine in ASR (93 to 96% of Cl component dechlorinated in

dry distillation stage)

(content of about 2.6%) is immobilized as CaCl2, NaCl, KCl, and other inorganic

salts or metal salts in the dry distillation residue. The rate of dispersal as gas is

estimated to be about 4 to 7%.

• The behavior of the chlorine was found from the following equations (1) and (2)

based on the results of the analysis of the concentration of the hydrogen

chloride and organic chlorine in the exhaust gas of combustion. Fig. 3.15 shows

the results.

• Note that the calculations covered the results of experiments in the case of

addition of 1.2% of Ca(OH)2

to the ASR.

[Findings Obtained]

• By kneading a certain amount (about 1.2% by ratio by weight) of Ca(OH)2

in the

ASR when compacting and solidifying the ASR, the chlorine in the ASR is

immobilized as inorganic salts at the time of the dry distillation, so the

concentration of HCl in the dry distillation gas is greatly reduced (Fig. 3.16).

Fig. 3.15. Total Balance of Chlorine (Calculated Values Found Based on Experimental Data)

Measured value of content of chlorine in solidified ASR (N=6): about 2.6%

Content of chlorine in solidified ASR

Dry distillation residue

Exhaust gas of combustion

4 to 7%

100% 93 to 96%

GCl : Mass ratio of chlorine released to air (%)SCl : Mass ratio of chlorine fixed in residue (%)MO : Mass of chlorine in solidified ASRQN1: Flow rate of exhaust gas in No. 1 furnace (Nm3/h)QN2: Flow rate of exhaust gas in No. 2 furnace (Nm3/h)t : Time (h)f(t) : Change in HCl concentration over time (ppm)

3.5.2. Effect of Reduction of HCl by Addition of Ca(OH)2

• Fig. 3.16 shows the concentration of HCl in the dry distillation gas in the case of

addition of Ca(OH)2to the ASR and the case of not adding it.

• When adding Ca(OH)2, the concentration of HCl is greatly reduced as shown by

the solid line in the figure. A clear effect of reduction due to the Ca(OH)2

is

observed.

• The effect was investigated with a rate of addition of Ca(OH)2

of 1.2% and 2.4%.

Not that much of a difference was observed as shown in the figure.

0

100

200

300

400

500

600

700

0 100 200 300 400 500 600

HCl c

once

ntra

tion

(ppm

)

No Ca(OH)2

(980825-4 )

Ca(OH)2: 1.2% added (980922-1)

Ca(OH)2: 2.4% added(981217-1,2)

Fig. 3.16. HCl Concentration in Dry Distillation Gas (Comparison of Case of Addition of Ca(OH)2 to ASR and Case of No Addition)

Average temperature of ASR ( C)

3.5.3. Effects of Dechlorination by Heating of Dry Distillation Gas

• As shown in Fig. 3.17, the dry distillation gas was passed through a separate

furnace under a high temperature atmosphere to heat and dechlorinate the

organic chlorine compounds in the dry distillation gas.

• In the experiment, the dry distillation gas obtained from the No. 3 furnace was

passed through a No. 4 furnace in a high temperature atmosphere of 400 to

700°C and heated for approximately 1.5 to 2.0 minutes. The concentration of

organic chlorine in the dry distillation gas was measured before and after the

heating to investigate the effect of dechlorination by heating.

• Fig. 3.18 and Fig. 3.19 show the CH3Cl before and after heating and the total

concentration of all organic chlorine compounds.

• As illustrated, the concentration of organic chlorine after heating was greatly

reduced in all experiments. A clear effect of dechlorination by heating was

observed.

• In the case of the heating temperature of 600 to 700°C and heating time of 1.5

to 2.0 minutes of Fig. 3.19, substantially all of the organic chlorine in the dry

distillation gas was thermally decomposed. The chlorine was believed to react

with the Ca, Na, K, and the like in the ASR to be immobilized as inorganic salts.

• The concentration of HCl in the exhaust gas of combustion, as shown in Fig.

3.20, declined from the conventional 300 ppm level to a level of 100 ppm. An

effect of reduction of HCl by heating the dry distillation gas was observed.

Fig. 3.18. Concentration of CH3Cl in Dry Distillation Gas Before and After Heating

Fig. 3.17. Experiment on Dechlorination by Heating of Dry Distillation Gas

Fig. 3.19. Concentration of Total Organic Chlorine in Same Dry Distillation Gas

0

50

100

150

200

250

300

350

400

450

500

0 2 3 4 5 6 7 8 9 10

Gas c

once

ntra

tion

(ppm

)

Time elapsed after convergence of dry distillation gas (h)

Before heating (No. 3 outlet) HCl(ppm)

After heating (No. 4 outlet) HCl(ppm)

Before heating (No. 3 outlet) CH3Cl(ppm)

After heating (No. 4 outlet)CH3Cl(ppm)

0

50

100

150

200

0 1 2 3 4 5 6 7 8 9 10

Conc

entra

tion

of o

rgan

ic ch

lorin

e (m

g/Nm

3 )

Time elapsed after convergence (h)

Concentration of total organic chlorine before heating (No. 3 furnace outlet)(mg/Nm3)

Concentration of total organic chlorine after heating (No. 4 furnace outlet)(mg/Nm3)

lower limit of amount

Dry distillation gas

Solidified ASR

Secondary incineration furnace

High temperature gas

No. 3 dry distillation furnace No. 4 dry distillation furnace

Dry distillation gas after dechlorination by heating

High temperature gas

Fig. 3.20. CH3Cl Concentration in Dry Distillation Gas Before and After Heating and HCl Concentration in Exhaust Gas of Combustion (Middle Part of Smokestack)

0

50

100

150

200

250

300

350

400

450

500

-2 -1 0 1 2 3 4 5 6 7 8 9

Conc

entra

tion

of C

H3Cl

and

HCl (

ppm

)

Time elapsed in heating (h)

No. 3 furnace outlet CH3Cl (ppm)

No. 4 furnace outlet CH3Cl (ppm)

Start of heating

High temperature furnace

Analysis of concentration of organic chlorine

High temperature furnace

Heating temperature of dry distillation gas: about 400 to 600 CHeating time: about 1.5 to 2.0 min

Heating temperature of dry distillation gas: about 600 to 700 CHeating time: about 1.5 to 2.0 min

HCl in secondary incineration furnace exhaust gas HCl (ppm)

3.6.1. Purity of Copper in Dry Distillation Residue

• It was not possible to recover almost any of the wire harness in the ASR by a

sorting equipment, but this could be relatively easily recovered from the dry

distillation residue. Therefore, JAMA investigated the temperature conditions of

the ASR during the dry distillation required for recovering the copper in the wire

harness in a high grade state.

[Findings Obtained]

• Fig. 3.21 shows the results of examination of the purity of the copper in the

residue by acid decomposition and ICP emission analysis.

• The results of the analysis shown are those in the case of a concentration of

oxygen in the high temperature gas of 2% and 4%. There is little data and a

definitive judgment is difficult, but overall if the temperature of the ASR is below

the 700°C level, the purity tends not to fall much at all.

• That is, to recover high grade copper from the dry distillation residue, it is

necessary to make the temperature of the ASR during the dry distillation a level

of less than 700°C.

3.6. Dry Distillation Residue

50

0

60

70

80

90

100

110

120

0 200 400 600 800 1000

Cu P

urity

(%)

High temperature gas O2 concentration : 2% (981027-3)

High temperature gas O2 concentration : 4% (981027-4)

Fig. 3.21. Relation of Hysteresis Temperature of ASR and Copper Purity

Solidified ASR Temp.( C)

3.6.2. Findings of Elution Test of Dry Distillation Residue

• JAMA conducted elution tests of the heavy metals etc. to evaluate the safety of

the dry distillation residue.

[Findings Obtained]

• The results of the elution test of the dry distillation residue, as shown in Table

3.2, were that all items were at levels below the standards for elution of toxic

substances of the Environmental Agency (Proclamation No. 13).

• The samples analyzed differed in the concentrations of oxygen in the high

temperature gas at the time of the experiments (<1.0% to 7%) and the rates of

addition of the Ca(OH)2

to the ASR (0% and 4.5%), but these differences were

not observed to have any effect on the results of the elution test.

RUN 3 RUN 9 RUN10 RUN11 RUN30 RUN31 RUN32

Standard values of Prime

Minister's Office directive

O2 concentration in high temperature gasRate of addition of Ca(OH)2 to ASR

<1.0% 4.40% 7.0% 4.4%0% 4.5%

Analyzed items unit

Cd mg/l <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.1CN mg/l <0.03 <0.03 <0.03 <0.03 <0.03 <0.03 <1O-P mg/l <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <1Pb mg/l 0.01 0.02 0.02 0.03 <0.01 <0.01 <0.1Cr 6+ mg/l 0.04 <0.02 <0.02 <0.02 <0.02 <0.02As mg/l <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.1T-Hg mg/l <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 <0.005

N.D.R-Hg mg/l <0.0005 <0.0005 <0.0005 <0.0005 <0.0005 <0.0005PCB mg/l <0.0003 <0.0003 <0.0003 <0.0003 <0.0003 <0.0003 <0.003

TCE mg/l <0.03 <0.03 <0.3PCE mg/l <0.01 <0.01 <0.1

DCM mg/l <0.02 <0.02 <0.2CCI4 mg/l <0.002 <0.002 <0.02

1.2DC mg/l <0.004 <0.004 <0.041.1DCE mg/l <0.02 <0.02 <0.2c-1.2DC mg/l <0.04 <0.04 <0.41.1.1TCE mg/l <0.3 <0.3 <31.1.2TCE mg/l <0.006 <0.006 <0.06Thiuram mg/l <0.006 <0.006 <0.06Simazine mg/l <0.003 <0.003 <0.03Thiobencarb mg/l <0.02 <0.02 <0.2BZ mg/l <0.01 <0.01 <0.1

Se mg/l <0.01 <0.01 <0.1

Test lot

Table 3.2. Results of Elution Test of Dry Distillation Residue

3.6.3. Adsorption Ability of Dry Distillation Residue

• To investigate the possibility of recycling of the dry distillation residue, JAMA

investigated the adsorption ability of the carbides obtained by froth flotation and

refinement of the dry distillation residue. Table 3.3 shows the results of

measurement of the specific surface area of the refined carbides. Table 3.4

shows examples of measurement of the specific surface area of other carbides.

[Findings Obtained]

• The specific surface areas of the carbides after froth flotation of the dry

distillation residue (before activation), as shown in the table, are substantially the

same values as that of bone black.

• That is, the dry distillation residue is both nontoxic and has an adsorption ability

such as known by activated charcoal. This property can possibly be utilized.

Sample Specific surface area (m2/g) Remark

F secondary froth 79

S secondary froth 72

Note 1) Measurement apparatus: Model 220 apparatus for automatic measurement of specific surface area made by Shimadzu. Note 2) The F in the table indicates the froth obtained by froth flotation of the residue, while the S indicates the sink. Note 3) The carbides measured were not activated.

Table 3.3. Results of Measurement of Specific Surface Area of Carbides After Froth Flotation of Dry Distillation Residue

Name of substance Specific surface area (m2/g)

10.5

70.8

242.1

119.2

309.0

1.76 - 5.41

13.8

4.0

276.0

165.2

1.5

20.2

6.5

46.0

Anatase

Bone black

Amorphous silica

Nickel catalyst

Catalyst

Zinc oxide

Aluminum oxide

Zirconium oxide

Alumina oxide

Silica alumina catalyst

Uranium oxide

Kaolin

Talc

Magnesium carbonate

Calcium carbonate 54.0

Note) Measurement apparatus: Model 2200 apparatus for automatic measurement of specific surface area made by Shimadzu.

Table 3.4. Example of Measurement of Specific Surface Area of Carbides

The samples were measured after a degasification operation conducted at 300 C for about 1 hour while charging with nitrogen gas.

• Fig. 3.22 shows the results of an investigation of the relation of the concentration

of the flammable gas in the thermally decomposed gas with the hysteresis

temperature of the ASR (average temperature of ASR as a whole).

• The amount of flammable gas generated tends to increase along with the rise of

the temperature of the ASR. In the steady state (average temperature of ASR of

over about 400°C), it is seen that gas of a total amount of heat generation of

about 12.9 MJ/Nm3 (3,100 kcal/Nm3) can be recovered relatively stably.

• The amount of heat generation is close to that of type 4C city gas. The

combustion limit (or explosive limit) is estimated to be about 19 to 37%.

• The THC component in the steady state is mainly comprised of methane as

shown in Fig. 3.23.

3.7. Dry Distillation Gas Components

0

5

10

0

20

40

60

80

100

15

20

25

Conc

entra

tion

(%)

Conc

entra

tion

(%)

Fig. 3.22. Relation between average Temperature of ASR and Flammable Gas Component

Fig. 3.23. THC Component in Flammable Gas

THC component

CH4

CH493.6

5.50.5 0.3 0.2

C2H6

C2H6

C3H8

C3H8

t-C4H10

t-C4H10

n-C4H10

n-C4H10

5.96MJ/Nm3

200 270 310 390 450

9.65MJ/Nm3

12.25MJ/Nm3

12.87MJ/Nm3

THC

H2

CO

Average temperature of ASR ( C)

• Fluidized bed incinerators and other generally used incineration furnaces

produce high concentrations of particulate matter and require dust collectors for

scrubbing the exhaust gas of combustion. The ash (fly ash) trapped by the dust

collectors contains dioxins, heavy metals, and other toxic substances.

This technology generates almost no fly ash, so the concentration of particulate

matter is extremely low and there is no need to install a dust collector.

[Findings Obtained]

• Table 3.5 shows the analysis of the concentration of particulate matter and

metals in the exhaust gas of combustion. As shown in the table, the

concentration of particulate matter is of a low level sufficiently below the

standard. Removal by a dust collector is not believed necessary. Further, the

concentration of metals was also of a low level.

• In the dry distillation and gasification, the ASR is heated and almost all of the

volatile matter is discharged in a gaseous state. Therefore, it is believed, unlike

in ordinary combustion, almost no fly ash is produced.

3.8. Particulate Matter and Metal Concentration

Table 3.5. Results of Analysis of Concentration of Particulate Matter and Metals in Exhaust Gas of Combustion

Results of analysis Emission standard RemarksParticulate matter concentration < 0.001 to 0.04000

(N=7)0.15 EU standard

(processing capability: up to 1 ton/h): 0.2(g/Nm3)

Results of measurement of metal concentration (unit: mg/Nm3)

Hg 0.031 to 0.092(N=4)

Pb 0.08 to 0.68, 2.6(N=3), (N=1) -

-

Cd 0.0058 to 0.044(N=4) -

Cr 0.013, 0.029(N=2) -

Cu 0.013 to 0.110(N=4) -

Zn 0.13 to 1.8(N=4) -

Note) N: number of samples.

EU standard (processing capability: over 6 ton/h)•Pb+Cr+Cu+Mn : 5•Cd+Hg : 0.2No standard for processing capability of under 6 tons

3.9. Findings of Examination of Cooling Tank Water Quality

[Findings Obtained]

• The quality of the water of the cooling tank was examined after the end of Run 7

and Run 17 of the dry distillation test. As a result, it was found that the

concentration of the toxic substances was of a low level sufficiently satisfying the

standard. It is believed that the used cooling water can be sufficiently treated by

ordinary simple treatment of wastewater. The results of the examination of the

water quality in the dry distillation residue cooling tank are shown in Table 3.6.

An important element in reducing the production of environmental load

substances in the dry distillation and gasification technology is the secondary

incineration facility for ensuring the dry distillation gas is completely burned. This

facility is an important one essential for safe technical development in that still

unknown dry distillation gas is handled. It was necessary to give it a performance

enabling gas of all properties to be completely burned. Therefore, the No. 2

secondary incineration furnace equipped with two combustion chambers was

installed to provide an incineration furnace having such a sophisticated

combustion performance.

In an initial test, the No. 2 secondary incineration furnace was used to burn the

dry distillation gas. Its properties were determined, then the No. 1 secondary

incineration furnace having a single combustion chamber was installed to provide

a secondary incineration furnace able to secure a sufficient required combustion

performance at as low a cost as possible. The combustion performances of the

two furnaces were then compared.

3.10. Shape and Basic Performance of Secondary Incineration Furnace

Table 3.6. Findings of Examination of Dry Distillation Residue Cooling Water Tank Water Quality

Item 1st 2nd Lower limit of amount

Appearance

Odor

Nonvolatiles

BOD

COD

TOC

ICElectrical conductivity

pH

Cd

Total CN

O-P

Pb

Cr 6+

As

T-Hg

R-Hg

PCB

w%

mg/l

mg/l

mg/l

mg/l

ms/m

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

mg/l

Colorless and transparent

None

Not detected

Not detected

Not detected

Not detected

Not detected

Not detected

Not detected

Not detected

Not detected

Some

1.8

10.8

0.05

0.14

<0.001

<0.03

<0.005

<0.002

<0.04

<0.005

<0.0005

<0.0005

<0.0003

1.1

7.3

6.2

36.6

1.0

1,580

9.08

No.2 Secondary Incineration Furnace

Auxiliary Burner

Auxiliary Burner

Pilot Burner

Pilot Burner

No.1 Secondary Incineration Furnace

AirBlower

Air Blower

Main Burner

Main Burner

Fuel Gas

Fuel Gas

Dry distillation gas

Dry distillation gas

LPG

LPG

No. 1 secondary incineration furnace No. 2 secondary incineration furnace

Size Outer diameter 2.3 m x height 4.2 m Main chamber outer diameter 2.3 m x auxiliary chamber outer diameter 2.3 m x height 13 m

Total height including smokestack: 13 m Total height including smokestack: 18.5 m

Type of combustion Swirl flow combustion Two-stage combustion

[Differences in size and other specifications]

Figure 3.24. Differences in Specifications and Structure of No. 1 and No. 2 Secondary Incineration Furnaces

[Findings Obtained]

The No. 2 secondary incineration furnace exhibited a superior performance right

from the start. It did not produce any smoke or other products of incomplete

combustion throughout the tests.

On the other hand, the No. 1 secondary incineration furnace had a poor

combustion performance from the start. By modifying it by removing the heat

storing bricks in the furnace and adding an auxiliary burner, however, it was

possible to obtain a combustion performance substantially the same as the No. 2

secondary incineration furnace except in the concentration of NOx.

The following table shows the basic performances. Note that the modifications are

explained in detail in Chapter 3. Main Section (CD-ROM version of report).

No. 1 secondary incineration furnace

No. 2 secondary incineration furnace

Emission standard Remarks

Diox ins (ng-TEQ/Nm 3)

0.0017, 0.115(N=2)

0.0045 to 0.1(N=3) 5

CO(ppm)

< 7 to 15(N=2)

< 12(N=1) 100

NOX(ppm)

87 to 140(N=5)

51 to 58(N=4)

250

SOX(ppm)

23 to 37(N=4)

14 to 45(N=3)

Restriction of total amount

Particulate matter (g/Nm3)

0.00720 to 0.016(N=4)

< 0.001 to 0.04000(N=3) 0.15

HCl(ppm)

12 to 363(Ave : 135)

(N=8)

1.8 to 155(Ave : 59.3)

(N=8)435

Results of measurement of metal concentration (unit: mg/Nm3)

Hg0.036 0.031 to 0.092(N=1) (N=3)

Pb2.6 0.08 to 0.68

(N=1) (N=3)

Cd 0.032 0.0058 to 0.044(N=1) (N=3)

Cr 0.013, 0.029(N=3)

Cu 0.03 0.013 to 0.110(N=1) (N=3)

Zn 1.80 0.13 to 1.5(N=3)

Amount of LPG used (Nm3)

Note) N: number of samples.

When operating one dry distillation furnace alone

When operating two dry distillation furnaces continuously

210 to 225 310 to 315

230 & 290 370 & 490

Note) Including 25 to 50 Nm3 worth of excess heat. Note) Including 55 to 85 Nm3 worth of excess heat.

Other: total power (kWh)

One dry distillation furnace alone

Two dry distillation furnaces continuouslyFour dry distillation furnaces continuously

Industrial water supply (m3)

Amount used per batch

450 to 600

About 800

About 1,300

1.15

•If combustion is stabilized, at level of less than 0.1 ng/Nm3 for both furnaces.•Four examples showing somewhat high values due to poor adjustment of combustion (0.7 to 1.8 ng/Nm3) were dropped from the study.

•The figures show the maximum values when operating two dry distillation furnaces continuously. •At the steady state, at a level of less than 1.0 ppm for both furnaces.•No differences due to differences in the furnaces were observed.

•The figures in the table show average values of results of continuous analysis over 3 to 5 hours.•Overall high values were shown by the no. 1 furnace.

•No differences due to differences in the furnaces were observed.

•The figures in the table show the results of Runs 13 and 14 and Runs 15 and 16 analyzed under substantially identical conditions.•The differences in the results of the analysis are believed due to the dry distillation conditions such as the concentration of oxygen in the dry distillation furnaces.

•The difference in the amounts used is due to the excess heat before inflow of the dry distillation gas, so there is almost no difference in flow rate at the steady state. (Flow rate at steady state: about 10 to 12 Nm3/h for both furnaces)

No differences due to differences in the furnaces were observed.

Table 3.7. Comparison of Basic Performance of No. 1 and No. 2 Secondary Incineration Furnaces

The target for the effective recycling rate is more than 95% (from 2015). During

JAMA's research program, however, only about 90% was achieved. Therefore,

JAMA decided to examine the recycling of the dry distillation residue. It focused

on the recovery of the copper in the dry distillation residue and the use of the

activated carbon performance of the dry distillation residue.

4.1.1. Preliminary Survey

(1) The dry distillation residue was confirmed to contain about 5% of copper.

It was learned that if the dry distillation residue is crushed by a ball mill,

the metals and non-metals can be separated well and that the metals etc.

can be sorted by use of screens of suitable sizes.

(2) Looking at the activated carbon performance, three studies, including a

test of the filtrate in the case of adding crushed dry distillation residue to

an iodine solution, showed that the residue has a weak activated carbon

performance. In view of the above, JAMA commissioned a basic technical

study to the Nihon Jiryoku Senko Co. in August 1998.

4.1.2. Object and Goals

The object of the study is to obtain basic technical information enabling refining of

products able to be used for the envisioned applications.

Further, the targets for refinement of the carbides are a carbon grade of at least

50% and a recovery rate of at least 95%.

4.1.3. Method

(1) Refining Products and Envisioned Applications

The following three products, including high carbon grade carbides, were

refined from the dry distillation residue and applications considered for

each.

[1] High carbon grade carbides: temperature raising materials for

steelmaking, carburizing materials, insulating materials, and

moisture adjusters for use under floors of housing

[2] Nonferrous metals with large copper content: Metal materials

[3] Other non-metals: Cement aggregate materials due to high silica

and alumina content.

4.1. Recycling Technology Using Wet crush of Dry Distillation Residue and Carbon Flotation

4. Basic Surveys Related to Utilization of Dry Distillation Residue

(2) Main Recycling Technologies

[1] Use of wet crush by a ball mill for sorting of carbides, metals, non-

metals, etc.

[2] Sorting of wet crushsh product by 1 mm mesh screens to sort the

metals etc. of over 1 mm size and, fur ther, the removal of

magnetic substances and sorting to obtain small carbide granules

of less than 1 mm size.

[3] Sorting of wet crushed product of less than 1 mm size by froth

flotation into froth and sink to obtain high carbon grade carbides

at the froth side.

[4] Sorting of the sink side product by specific gravity into a heavy

fraction (metals), medium fraction (glass etc.), and light fraction

(carbides etc.) (Experiments by the method of sorting by specific

gravity were not possible this time.)

4.1.4. Findings Obtained

(1) A large amount of information was obtained by the basic technical study.

[1] For the carbides, the possibility was found of processing the dry

distillation residue of a dry distillation hysteresis temperature of

550 to 650°C by froth flotation to obtain second froth of 49 to 50%

carbon at a yield of 45 to 55% and a rate of recovery of 86 to 98%.

[2] It was confirmed that mostly copper nonferrous metals could be

obtained in the nonmagnetic fraction (about 7% of dry distillation

residue) of magnetic separation of dry distillation residue of more

than 1 mm size. Further, the magnetic fraction (about 3% of the

dry distillation residue) of the dry distillation residue of more than 1

mm size can probably be recycled as iron and steel materials.

(2) The sink fraction produced in froth flotation (about 40% of dry distillation

residue) corresponds to about 18% of the current ASR being disposed of

at landfills. If not recycled, the current recycling rate of 75% to 80% would

be raised to 94% to 95%.

(3) Dechlorination of the froth side and sink side fractions is possible by

washing with water.

(4) Reducing the size of the granules for the froth flotation to less than 100

microns could help improve the carbon grade.

(5) Solidification of the carbides requires use of different types of shaping

machines depending on the final application.

4.1.5. Future Issues

(1) Experiments should be conducted on stably obtaining carbides,

nonferrous metals, and nonmetals on an actual operating scale (a

processing capability of 200 kg/h at a minimum) and on reproducing the

results obtained in the basic technical study,

(2) A market survey should be conducted on the recycling of the carbides

and other products for the envisioned applications.

100

90

80

70

60

50

40

30

20350 550 750

Grad

e (%

)

Hysteresis temperature

Reco

very

rate

Yield

(%)

Carbon gradeYieldRecovery rate

Fig. 4.1. Carbon Grade, Yield, and Recovery Rate of Dry Distillation Residue by Temperature Hysteresis

The CEP (catalytic extraction processing) method was developed by Molten

Metal Technology of the U.S. It calls for blowing refuse into an iron melting bath to

break down all of the substances to the atomic level and adjusting the pressure,

temperature, and amount of oxygen fed to control the chemical composition of the

resultant product.

Therefore, compared with "direct incineration and melting" and "surface melting

technology" which melt the inorganics in the same composition as at the inlet, this

4.2. Survey of Slag-Forming Technology of Dry Distillation Residue Using CEP

technology enables the

control of the content of the

heavy metals in the molten

slag and therefore gives a

clean slag.

The trace components of the

molten slag obtained by

processing ASR by the CEP

method and the molten slag

obtained by experiments by

the surface melting technolo-

gy were analyzed. The results

are shown in Table 4.1. Fig. 4.2. Catalytic Extraction Processing Technology

Refuse + oxygen

SlagMolten metal

Flammable gas

Molten iron catalyst

Water cooling coil (electromagnetic induction heating)

Incineration, heat recovery power generation, exhaust gas treatment

[Findings Obtained]

• Comparing the two slags using as a representative case the chrome in the

heavy metals, no elution could be detected in either by the method of

measurement prescribed by the Environmental Agency (Proclamation No. 13).

The content however was found to be 160 ppm by the CEP method and 2800

Table 4.1. Composition of Trace Elements in Molten Slag

Trace element

Guideline (ppm)

Measured value (ppm)

30

3-5

1,000

3

1

200

100

200

1,000

75

0.5

200

5

2

30

300

400

1

<1

4,420

3

<0.5

160

10

170

<200

18

0.03

<10

5

<1

1

12

<10

<Reference> surface melting

1.95

0.82

2,800

17,200

53

<0.01

205.5

260

As

Sb

Ba

Be

Cd

Cr

Co

Cu

Cl

Pb

Hg

Se

Ni

Ti

Sn

V

Zn

ppm by the surface melting method,

i.e., a clean slag could be obtained

by the former method. The reason is

that in the CEP method, the chrome

is controlled to migrate to the molten

iron, while is left as it is in the

surface melting method.

• The "guidelines" of Table 4.1 relate to

the content of the trace components

and were established assuming use

for cement aggregate materials in

Switzerland. Experiments showed

that the content of all of the com-

ponents other than barium was

below the guidelines. Further,

barium itself is not particularly toxic.

It was therefore learned that the slag

can be used for the aggregate

material for cement.