It is a fact that sprinklers and water

jets have already been used for a

long time to control dust, but the

Belgian company Jet-Zone bvba

in Zwevegem, an affiliate of Savic

Engineering, is doing it much more

efficiently. Their technology con-

sists of two basic principles:

- A very fine spray covers a very

large surface over which dust

particles can be caught. The vol-

ume of water in a standard sized

rain drop is equivalent to 8,000

spray particles.

- Control at source. The most effi-

cient way to eliminate particu-

late matter, which also gives the

best results, is controlling it right

where it is generated. In this

case, that happens to be the

crusher chamber. That is exactly

where Jet-Zone injects its fine

mist.

Principle

The water spray principle in itself is

relatively easy. “Take an injector

with a sufficiently small opening,

apply high water pressure and

there you go, there is your water

spray”, says Jet-Zone director Ni-

colas Malfait . “The innovating

part of our water spray technolo-

gy however is the injector’s loca-

tion, completely fitted within the

crusher chamber and still perfectly

protected against the shredded

material’s impact.”

The art consists of catching as

much dust as possible with the

spray without moistening the ma-

terial. This is a fundamentally differ-

ent and better approach than all

existing technologies. The power-

fully injected spray permeates

deep into the crushing chamber’s

core giving an even spread of

spray thereby delivering the best

performance.

Additive

Malfait explains also that: “In order

to further improve attaching the

dust particles to the spray parti-

cles, we have developed an addi-

tive. First we examined the dust’s

characteristics. Within the crusher

chamber itself, heat is generated,

causing the water to evaporate.

The additive on the other hand

enables the dust particles to bind,

making them heavier and causing

them to drop down again on the

shredded material.” Thanks to the

limited volume of water, the mate-

rials’ stream does not get wet and

the quality of the resulting materi-

als’ stream improves. Malfait also

says: “Moreover, the little bit that’s

left for landfill does not get any

heavier and therefore increased

dumping costs because of the

added water are no longer an

issue either.”

Innovation

The system’s innovation is its injec-

tors and intelligent control. Malfait

also says:“The injector must survive

in a chamber which also houses a

rotor doing its destructive work

and that is not an easy task. Mate-

rials are banged with great force

against the chamber’s walls and

the injector must be able to resist

that.”

Jet-Zone has designed an intelli-

gent version which does not re-

quire any adjustments to the

crusher chamber. In order to pro-

tect the crusher chamber itself,

wearing plates are fitted using

If there is one activity where dust is generated, it is when car wrecks

are recycled using giant shredders. That is because cars are mainly

made of textiles and quickly crumbling plastic materials. In an effort

not to burden the environment too much when crushing a car wreck,

all sorts of techniques are implemented to control any dust generat-

ed. Recently another technique has been added to that list: control

at source using a fine water spray.

Fog-Injection against shredder dust

Source: publication Recycling-Magazine—june 2013

Picture 1: Dust generation before (a) and after (b) fitting Jet-Zone’s equipment; improvement is clearly visible

bolts. Depending on the crusher’s capacity 2, 4 or 6 bolts are re-

moved and replaced with injector

holders.

The injector holder’s size is the

same as the bolt’s and can also

be used to tighten the wearing

plate again. The holder has an

opening which fits the Jet-Zone

injector perfectly, protecting it

against the powerful bangs. The

injector is also fitted with a spring

so that it can absorb a certain im-

pact. Auxiliary components such

as high pressure hoses are located

outside of the crusher chamber

and all other components such as

high pressure pumps and their

controls are located in a contain-

er placed outside of the machine.

Results

Thanks to injecting a water spray

right within the chamber’s core,

using 500 to maximum 2,000 litres

of water an hour when producing

300 tonnes of material per hour,

particulate matter emissions are

greatly avoided. The volume of

water is easily controlled. Under

damp weather conditions, less

spray is needed than for example

during hot summer days with low

humidity levels. The volume of wa-

ter can be manually adjusted and

employees can easily see if suffi-

cient spray is used.

In practice

Cometsambre, an affiliate of the

Belgian Comet group (see frame),

is one of the first users of the Jet-

Zone system. Implementation of

the system is managed by Vincent

Bodson, managing director of

Comet Technique, the depart-

ment responsible for implementing

new techniques. He explains: “The

Jet-Zone fog injection fits perfectly

in our quest for lower particulate

matter emissions, whatever source

they are from. We have placed

meters all around our site in order

to gauge once a month the

amount of dust caught. After in-

stalling the Jet-Zone fog injection,

this amount has halved, which is a

fantastic result, especially if you

take into account that it is not only

us who generate dust, but other

factories as well, such as the ce-

ment factory next door. We can

therefore confidently assume that

Jet-Zone reduces the crusher’s

emissions by more than 50%. I

have actively been looking for

solutions for more than 20 years

and I believe that with the Jet-

Zone fog injection, we have at last

found a decent working system.

Our water consumption has also

been drastically reduced be-

cause we no longer have to apply

jets of water in order to control

dust generation, thereby also re-

ducing our dumping costs. Anoth-

er couple of advantages are that

our installations remain clean and

there are no water puddles

around them.”

COMET GROUP AND THE ENVIRONMENT

Cometsambre, an affiliate of the Belgian Comet group, has a recycling plant in Obourg (near Mons) and in Châtelet (near Charleroi). Obourg is the location of Europe’s largest shredder: it is a 7,000 hp (more than 5 MW) Metso Lindemann Power Zerdirator with a capacity of 300 tonnes per hour. Cometsambre’s main activity is recycling ferrous and non-ferrous materials. The main stream leaving Obourg’s shredder is immediately usable by the foundry and any auxiliary streams are taken to Comet Traitements, also in Châ-telet. Vincent Bodson is Comet Technique’s managing director and responsible for managing the introduction into this department responsible for implementing new techniques and developments. He says: “The Comet’s group philosophy is to fully comply with all envi-ronment requirements and in order to do that use the best technologies available.”

Picture 2: One injector’s spray jet. It is clear to see that the injector has been fitted fully protected