Harmonisation of leaching test methods in support of EU ......CEN/TS 14997 Chemical speciation aspects Time dependent aspects of release Same as granular + Standardisation: CEN/TC292,

Harmonisation of leaching test methods in support of EU regulations controlling beneficial use of industrial slag in constructionHans van der Sloot, Andre van Zomeren, Rob Comans and Ole Hjelmar

Outline

Status of standardisation of leaching tests

Regulatory context

Leaching test results for steel slag

Use of leaching test in assessing impact

Practicality of testing

Benchmarking

28/04/20112 Harmonisation of leaching test methods │ Hans van der Sloot, Andre van Zomeren, Rob Comans and Ole Hjelmar

pH Dependence test

nchemicalanalyses

LnLBLA

n samples

S2 SnnBA

S1

0.01

0.1

1

10

100

1000

2 4 6 8 10 12 14Leachate pH

Co

pp

er

[mg

/L]

Titration Curve and Liquid-solid Partitioning (LSP) Curve as Function of Eluate pH

3

Equilibrium Leaching Test Parallel batch as function of pH

Test Specifications 8 specified target pH values plus natural

conditions Size-reduced material L/S = 10 mL/g-dry Dilute HNO3 or NaOH Contact time

48 hours

Reported Data Equivalents of acid/base added Eluate pH and conductivity Eluate constituent concentrations

28/04/2011Harmonisation of leaching test methods │ Hans van der Sloot, Andre van Zomeren, Rob Comans and Ole Hjelmar

Advantages of pH dependence test

- Identification of sensitivity of leaching to small pH changes

- Provides information on pH conditions imposed by external influences

- Basis for comparison of international leaching tests

- Basis for geochemical speciation modelling

- Provides acid neutralization capacity information

- Mutual comparison of widely different materials to assess similarities in leaching behaviour

- Recognition of factors controlling release

- For non-interacting species possibility to assess sub-sampling error

Applicable to almost any material

4 28/04/2011Harmonisation of leaching test methods │ Hans van der Sloot, Andre van Zomeren, Rob Comans and Ole Hjelmar

0.01

0.1

1

10

100

1000

1 3 5 7 9 11 13

pH

Lea

ch

ed

at

L/S

=1

0 (

mg

/kg

)

Cd

INGESTION

INHALATION

CEMENT STABILIZATION OF

CONTAMINATED SOIL

NATURAL SOIL

ACIDIC

ENVIRONMENTS

SOIL

LIMING

Test conditions related to differentexposure conditions

Relevant pH domains for assessing different questions in relation to different types of impact

Heavily Sewage Sludge Amended

Soil

Total


Local Equilibrium Leaching Test

Percolation through loosely-packed material

Test Specifications

5-cm or 10 cm diameter x 30-cm high glass column

Size-reduced material

DI water or 1 mM CaCl2 (clays, organic materials)

Upward flow to minimize channeling

Collect leachate at cumulative L/S0.1, 0.2, 0.5, 1, 2, 5, 10 mL/g-dry

Reported Data Eluate volume collected Eluate pH and conductivity Eluate constituent concentrations

Percolation Test

air lock

eluant collection bottle(s)(sized for fraction volume)

Luer shut-offvalve

eluant reservoir

end cap

end cap

1-cm sandlayers

pump

subjectmaterial

Luer shut-offvalve

Luer fitting

Luer fitting

N2 or Ar (optional)

Liquid-solid Partitioning (LSP) Curve as Function of L/S; Estimate of Pore Water Concentration


Advantages of percolation test

- Identification of solubility control versus wash out

- Indication of pore water concentrations relevant to field leachatefrom low L/S data (here is where single batch test fail)

- Local equilibrium established quite rapidly

- Basis for geochemical reaction-transport modelling

- Allows comparison with lysimeter and field data provided L/S value can be obtained from such measurements

- Projection towards long term behaviour possible (L/S-time relationship) taking preferential flow into account

Applicable to many materials. Limited or not applicable to clayey soils and sediments (low permeability).


Monolith Leach test

Mass-Transfer Test

Semi-dynamic tank leach test

Test Specifications

Material forms monolithic (all faces exposed) compacted granular (1 circular face exposed)

DI water so that waste dictates pH

Liquid-surface area ratio (L/A) of 9±1 mL/cm2

Refresh leaching solution at cumulative times 2, 25, 48 hrs, 7, 14, 28, 42, 49, 63 days

Reported Data Refresh time Eluate pH and conductivity Eluate constituent concentrations

1 Sample

nanalyticalsamples

A1

L1

A2 An

L2 Ln

Δt1 Δtn

orMonolith

CompactedGranular

n Leaching Intervals

Δt2

Flux and Cumulative Release as a Function of Leaching Time

Granular

Monolithic

0.001

0.01

0.1

1

10

100

1000

0.01 0.1 1 10 100

Cr

Rele

ase [

mg

/m2]

Leaching Time [days]

Availability

MDL

ML


Advantages of tank test or CGLT (compacted granular leach test)

- Relevant for materials with monolithic character (durable materials) or materials behaving as monolith (low permeability soil and sediments)

- Identification of solubility control versus dynamic leaching possible

- Isolation of surface wash-off effects

- Quantification of intrinsic release parameters

- Basis for reactive/transport modelling

- Projection towards long term behaviour possible

Applicable to stabilised materials, construction products, sediments and clayey soils.


Development of Standards and Materials Covered

Test/Matrix

Soil, sediments,

compost and

sludge Waste Mining waste Construction products

pH dependence test ISO/TS21268-4 CEN/TS14429 CEN/TS14429 CEN/TS14429

CEN/TS14497 CEN/TS14497

EPA 1313 * EPA 1313 EPA 1313 EPA 1313

Percolation test ISO/TS21268-3 CEN/TS14405 CEN/TS14405 CEN/TC351/TS-3

EPA 1314 * EPA 1314 EPA 1314 EPA 1314

Monolith test CEN/TS15683 CEN/TC351/TS-2

EPA 1315 * EPA 1315 EPA 1315 EPA 1315

Compacted granular test NEN7347 CEN/TC351/TS-2

EPA 1315 EPA 1315 EPA 1315 EPA 1315

Redox capacity NEN 7348 NEN 7348

Acid rock drainage PrEN15875

Reactive surfaces

ISO/CD12782

parts 1-5

* EPA drafts in preparation for inclusion in SW846

Same basic testing approach in different fields

Vienna agreement


Steps in validation

From: CEN Guide on validation tasks in the process of standardisation of environmental test methods, April 2008, ENV TC 215rev, supported by SABE Resolution 06/2008 -Validation policy

This is the status today:

- CEN/TC351 Robustness work granted (TS-2 and TS-3)

- US EPA Intercomparison validation in progress (pH dependence, percolation , monolith, CGLT) Results available end 2011

- CEN/TC292 still seeking funds


Use in blended cement

Raw material input in cement production process

Aggregate in concrete

Road base stabilisation

Embankment fill

Coastal protection

Soil improver

Steel slag Uses

With multiple uses of the same material or product multiple testing and judment approaches undesirable.

Single step tests are clearly insufficient to answer questions related to possible environmental impact.


Construction Products Directive (EU CPD)

Construction Products Regulation (EU CPR).

European Landfill Directive (EU LFD)

End of Waste regulation (EU EoW)

Waste Catalogue (EU WC)

Hazardous Waste Directive (EU HW)

REACH Regulation

Soil Quality Regulation – Fertilizer use

Groundwater Directive

Regulatory context

With multiple regulations : preferably not multiple testing and multiple impact judment approaches for the same material or product


TANK LEACH TEST MONOLITH CEN/TS 15863 and EPA Draft method

1315 and COMPACTED

GRANULAR LEACH TEST (NEN 7347 and EPA method

1313).

PERCOLATION LEACHING TEST CEN TS 14405 or EPA Draft method

1314

GRANULAR MATERIALS

MONOLITHIC MATERIALS

or

pH DEPENDENCE TEST: BATCH MODE ANC, CEN/TS 14429, or EPA Draft method 1313or, COMPUTER CONTROLLED CEN/TS 14997

Chemical speciation aspects Time dependent aspects of release

Same as granular +

Standardisation: CEN/TC292, ISO/TC190, CEN/TC345, CEN/TC351, SW846 (US EPA)

Characterisation leaching tests

Test set covers almost any practical condition for any material


Leaching of substances from granular materials is assessed by a column leaching test (CEN/TS14405) and pH dependence leaching test CEN TS/14429)

The column test provides insight in the release behaviour of substances.

Salts are generally not interacting with the matrix and thus released within a liquid to solid ratio (L/S) of 1

Many trace contaminants are solubility controlled

In a column upflow test preferential flow is minimized to ensure repeatability and reproducibility of test data

Under field conditions a substantial part of the application can be identified as stagnant (dual porosity model)

Release from granular materials


Identification of release processes from testing of granular materials

0 .1

1

1 0

1 0 0

0 .1 1 1 0 1 0 0

L/S (l/k g )

Le

ac

he

d (

mg

/kg

)

F

SO L U B IL IT Y

C O N T R O L

F0 .1

1

1 0

1 0 0

4 6 8 1 0 1 2

pH

Le

ac

he

d a

t L

/S=

10

(mg

/kg

)

0 .0 1

0 .1

1

1 0

0 .1 1 1 0 1 0 0

L/S (l/k g )

Co

nc

en

tra

tio

n (

mg

/l)

F

Cl

1 0 0

1 0 0 0

1 0 0 0 0

4 6 8 1 0 1 2

pH

Le

ac

he

d (

mg

/kg

)

1 0 0

1 0 0 0

1 0 0 0 0

0 .1 1 1 0 1 0 0

L/S (l/k g )

Cu

mu

lati

ve

re

lea

se

(m

g/k

g)

Cl

W A SH O U T

1

1 0

1 0 0

1 0 0 0

1 0 0 0 0

0 .1 1 1 0 1 0 0

L/S (l/k g )

Co

nc

en

tra

tio

n (

mg

/L) Cl


0.01

0.1

1

10

100

1000

10000

2 4 6 8 10 12 14

Co

nce

ntr

ati

on

(m

g/k

g)

pH

pH dependent concentration of Cr

CEN/TS14429

Total

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

0.01 0.1 1 10

Cu

mu

lati

ve

re

lea

se

(m

g/k

g)

pH

Cumulative release of Cr

CEN/TS14405

Dutch SQD

Judgment of environmental impact ontotal composition or on leaching?

Relevance of total composition for environmental judgment questionable. Leaching by far more relevant for

environmental impact assessment and bioavailability

Steel slag BOF


28/04/2011Harmonisation of leaching test methods │ Hans van der Sloot, Andre van Zomeren, Rob Comans and Ole Hjelmar18

Substances can be judged at different levels:

- Total content is generally a poor measure for environmental or health impact as often a small fraction of the total is assessible for uptake or transport

- Potentially leachable (available) is a next level, which can be considered a worst case approach

- Actual leaching in a pH and L/S domain of relevance to the application provides a good measure of possible exposure

- In some case chemical speciation can provide proof that the form in which substances are released is less harmful than assuming the most sensitive form

Understanding of chemical speciation is important for adequate control measures in case of product improvement

Judgment of environmental impact ontotal composition or on leaching?

Data Management Tools

Data Templates Excel® Spreadsheets for Each Method

Perform basic, required calculations (e.g, moisture content)

Record laboratory data

Archive analytical data with laboratory information

Form the upload file to materials database

LeachXS (Leaching eXpert System) LiteTM

Data management, visualization and processing program

Compare Leaching Test Data Between materials for a single constituent (e.g., As in two different CCRs)

Between constituents in a single material (e.g., Ba and SO4 in cement)

To default or user-defined “indicator lines” (e.g., QA limits, threshold values)

Export leaching data to Excel spreadsheets

Freely available at http://www.vanderbilt.edu/leaching

Full LeachXSTM including geochemical tools (subscription fee)

19November 16,

2010EPA LTIG Conference Call

19

http://www.vanderbilt.edu/leaching

Leaching behaviour of steel slag types

28/04/201120

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

2 4 6 8 10 12 14

Co

nce

ntr

ati

on

(m

g/L)

pH dependent concentration of Al

0.001

0.01

0.1

1

10

100

0.01 0.1 1 10 100Cu

mu

lati

ve

re

lea

se

(m

g/k

g)

Cumulative release of Al

0.0001

0.001

0.01

0.1

1

10

2 4 6 8 10 12 14

Co

nce

ntr

ati

on

(m

g/L)

pH

pH dependent concentration of Ba

0.0001

0.001

0.01

0.1

1

10

100

0.01 0.1 1 10 100Cu

mu

lati

ve

re

lea

se

(m

g/k

g)

L/S (L/kg)

Cumulative release of Ba

Harmonisation of leaching test methods │ Hans van der Sloot, Andre van Zomeren, Rob Comans and Ole Hjelmar

0.0001

10

2 12

Co

nce

ntr

ati

on

(m

g/L)

pH

pH dependent

concentration of Ba

EAF

LD slag

Not specified

BF

BOF


0.00001

0.0001

0.001

0.01

0.1

1

10

100

2 4 6 8 10 12 14

Co

nce

ntr

ati

on

(m

g/L)

pH dependent concentration of Cr

0.00001

0.0001

0.001

0.01

0.1

1

10

0.01 0.1 1 10 100

Cu

mu

lati

ve

re

lea

se

(m

g/k

g)

Cumulative release of Cr

0.00001

0.0001

0.001

0.01

0.1

1

10

2 4 6 8 10 12 14

Co

nce

ntr

ati

on

(m

g/L)

pH

pH dependent concentration of Ni

0.00001

0.0001

0.001

0.01

0.1

1

0.01 0.1 1 10 100Cu

mu

lati

ve

re

lea

se

(m

g/k

g)

L/S (L/kg)

Cumulative release of Ni


0.0001

10

2 12

Co

nce

ntr

ati

on

(m

g/L)

pH

pH dependent

concentration of Ba

EAF

LD slag

Not specified

BF

BOF


0.0001

0.001

0.01

0.1

1

10

100

2 4 6 8 10 12 14

Co

nce

ntr

ati

on

(m

g/L)

pH dependent concentration of V

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

0.01 0.1 1 10 100Cu

mu

lati

ve

re

lea

se

(m

g/k

g)

Cumulative release of V

0.00001

0.0001

0.001

0.01

0.1

1

10

2 4 6 8 10 12 14

Co

nce

ntr

ati

on

(m

g/L)

pH

pH dependent concentration of Zn

0.0001

0.001

0.01

0.1

1

10

0.01 0.1 1 10 100Cu

mu

lati

ve

re

lea

se

(m

g/k

g)

L/S (L/kg)

Cumulative release of Zn


0.0001

10

2 12

Co

nce

ntr

ati

on

(m

g/L)

pH

pH dependent

concentration of Ba

EAF

LD slag

Not specified

BF

BOF


0.00001

0.0001

0.001

0.01

0.1

1

2 4 6 8 10 12 14

Co

nce

ntr

ati

on

(m

g/L)

pH dependent concentration of Mo

0.00001

0.0001

0.001

0.01

0.1

1

10

0.01 0.1 1 10 100Cu

mu

lati

ve

re

lea

se

(m

g/k

g)

Cumulative release of Mo

0.01

0.1

1

10

2 4 6 8 10 12 14

Co

nce

ntr

ati

on

(m

g/L)

pH

pH dependent concentration of F

0.001

0.01

0.1

1

10

100

0.01 0.1 1 10 100Cu

mu

lati

ve

re

lea

se

(m

g/k

g)

L/S (L/kg)

Cumulative release of F


0.0001

10

2 12

Co

nce

ntr

ati

on

(m

g/L)

pH

pH dependent

concentration of Ba

EAF

LD slag

Not specified

BF

BOF

- Different users of the release information have different needs. Both regulators and industry need information with sufficient detail to allow proper judgment of the materials in their intended use scenario.

Tiered approach in testing

Level of

detail

Frequency

of testing

“compliance” testing

“characterization” testing

Level of

detail

Frequency

of testing

“compliance” testing

“characterization” testing

Factory production control

Initial type testing/ Characterisation

- Once the release characteristics of a product type or class are established much simpler conformity testing will suffice for potentially critical parameters only at a frequency consistent with the risk of approaching/ exceeding set limit values by notified regulations.


Statistics applied to consistent data sets for quality control purposes

28/04/201125

1E-05

1E-04

1E-03

1E-02

1E-01

1E+00

1E+01

1E+02

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

Conce

ntr

ation (m

g/L

)

pH

Cr

Harmonisation of leaching test methods │ Hans van der Sloot, Andre van Zomeren, Rob Comans and Ole Hjelmar

Mean value for product type

Upper 90 % confidence interval

Lower 90 % confidence interval

Full test comparison

Single data point comparison

Benchmark Steel slag - pH dependence

Role of Characterisation Leaching Tests in Environmental Judgement of Materials

Quality control of products Product improvement

Development of limit valuesRelation lab-practice (Scenarios)

Modelling

Product modificationMeasurement for verification

Efficient measurementsPrecision measurement data

Characterisation leaching tests(identification of mechanisms and

processes)

Assessibility of data: data base/expert system LeachXS

Development of criteria for regulation

Application of regulatory criteria

Judgement of applications


Primary Raw Materials

Alternative raw materials

Stage 1 Raw material supplies

Stage 2:Manufacture of construction materials and elements

Recycling of construction debris

Stage 4:Service Life

Stage 3:Construction ProcessStage 5:

Demolition

Release into the environment

Energy

Dust, noise emissions

Energy

“End of Life”

Environmental impact (dusting)

Supply of information on technical and environmental

quality: Database/

expert system

Characterisation (ITT) of monolith/ granular leaching behaviour of the product

Monolith/granular QC, conformity or

compliance leaching test

Characterisation of granular leaching behaviour

Granularcompliance test

Tiered approach linked to the building cycle


CPD -> CPR

1. pH dependence leaching test on granular material or size reduced monolithic material for chemical speciation purposes

2. measurement of release from granular materials in a percolation test or from monolithic specimen according to a type of tank test

3. speciation modelling to identify relevant mineral phases (SI-indices)

4. refined description of multi element leaching behaviour in a pH dependence test based on the selected minerals and other relevant phases (Fe, Al, DOC, etc) providing a chemical speciation fingerprint (CSF)

5. the resulting chemical speciation fingerprint (CSF) is used as input for the chemical reaction/transport modelling to describe the release from a percolation test or from a monolithic specimen (tank test simulation).

6. model the field scenario using the CSFs for the different layers of material involved using external factors (carbonation, oxidation, biologically mediated reactions) and realistic estimates of infiltration (e.g. preferential flow)

Steps in chemical speciation modelling


Input (Chemical Speciation Fingerprint)

- Element availabilities (major minor and trace elements from pH dependence test)

- Liquid to Solid ratio (L/S=10)

- Redox status of material/product pH+pe = 15 (oxidised)

- Clay content (kg/kg)

- Reactive Hydrated Ironoxide surface (HFO in kg/kg)

- Reactive Solid Humic Acid (SHA in kg/kg)

- Dissolved Organic Carbon (DOC in kg/l from pH dependence test)

- Selection of potentially relevant minerals controlling solubility (Partly taken from a model run to determine saturation indices (SI) for all available minerals in the thermodynamic database)


Example Input (Chemical Speciation Fingerprint)


Prediction case Steelslag Carb + columnAA EA DOC/DHA data

Speciation session Steelslag Carb + columnAA EA pH [DOC] (kg/l) DHA fraction [DHA] (kg/l)Polynomial coeficients

Material Steel_slag_carbonated_30% (P,1,1) 1.00 2.000E-05 0.20 4.000E-06 C0 -5.775E+00

2.09 1.000E-05 0.20 2.000E-06 C1 6.397E-01

Solved fraction DOC 0.2 3.56 4.000E-06 0.20 8.000E-07 C2 -3.793E-01

Sum of pH and pe 15.00 5.19 4.250E-06 0.20 8.500E-07 C3 6.435E-02

L/S 10.4258 l/kg 6.49 1.000E-06 0.20 2.000E-07 C4 -4.332E-03

Clay 0.000E+00 kg/kg 8.07 1.000E-06 0.20 2.000E-07 C5 1.017E-04

HFO 3.000E-03 kg/kg 9.58 6.300E-06 0.20 1.260E-06

SHA 2.000E-04 kg/kg 11.42 7.100E-06 0.20 1.420E-06

Percolation materialsteelslag_Corus_K1RCS_treated_1 (C,1,1) 12.55 2.400E-06 0.20 4.800E-07

Avg L/S first perc. fractions 0.1495 l/kg 14.00 3.000E-06 0.20 6.000E-07

Reactant concentrations

Reactant mg/kg

Ag+ not measured Fe+3 1.573E+04 Mn+2 7.044E+03 SO4-2 1.011E+03

Al+3 4.689E+03 H2CO3 4.200E+04 MoO4-2 9.358E-02 Sr+2 8.935E+01

Ba+2 5.684E+01 H3AsO4 8.351E-01 Na+ 8.996E+01 VO2+ 7.311E+02

Ca+2 1.588E+05 H3BO3 3.080E+01 Ni+2 4.627E+00 Zn+2 2.103E+01

Cd+2 1.300E-01 H4SiO4 6.864E+03 Pb+2 4.871E+00

CrO4-2 6.560E+01 K+ 1.580E+02 PO4-3 1.016E+03

Cu+2 5.644E+00 Li+ 4.572E-01 Sb[OH]6- 3.464E-01

F- not measured Mg+2 1.211E+04 SeO4-2 2.407E+00

Selected Minerals

AA_2CaO_Al2O3_SiO2_8H2O[s] AA_Fe[OH]3[am] Barite Ca3[VO4]2 Fe2[MoO4]3[1] Ni[OH]2[s] Rhodochrosite

AA_2CaO_Fe2O3_SiO2_8H2O[s] AA_Gibbsite BaSrSO4[50%Ba] Ca4Cd[PO4]3OHFerrihydrite Ni2SiO4 Sphalerite

AA_3CaO_Al2O3[Ca[OH]2]0_5_[CaCO3]0_5_11_5H2O[s] AA_Gypsum beta-TCP Calcite Fluorite OCP Strengite

AA_3CaO_Al2O3_6H2O[s] AA_Portlandite Boehmite CaMoO4[c] Huntite Otavite Strontianite

AA_3CaO_Al2O3_CaCO3_11H2O[s] AA_Tobermorite-I Brucite Cd[OH]2[C] Laumontite Pb[OH]2[C] Tenorite

AA_3CaO_Fe2O3_CaCO3_11H2O[s] AA_Tricarboaluminate Ca_Vanadate Cr[OH]3[A] Magnesite Pb2V2O7 Wairakite

AA_Calcite Ba[SCr]O4[96%SO4] Ca2Cd[PO4]2 Diaspore Manganite Pb3[VO4]2 Willemite

AA_CO3-hydrotalcite BaCaSO4[75%Ba] Ca2V2O7 Fe_Vanadate Morenosite PbMoO4[c] ZnSiO3

Input specification

Chemical speciation modelling of carbonated steel slag


-15

-10

-5

0

5

10

15

1 3 5 7 9 11 13

AN

C/B

NC

(m

ol/

kg

)

ANC/BNC

1.0E-10

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

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

Al

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+02

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

Ca

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

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

Co

ncen

trati

on

(m

ol/

l)

pH

Fe

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

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

pH

Si1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

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

pH

PO4 as PCEN/TS14429

CEN/TS14405Percolation

Model description at L/S=10

Model prediction at L/S=0.2


1.0E-10

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

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

Co

ncen

trati

on

(m

ol/

l)

pH

Ni

1.0E-10

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

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

pH

Pb1.0E-10

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

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

pH

Zn

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

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

Co

ncen

trati

on

(m

ol/

l)

pH

Cr

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

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

pH

Mo

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

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

pH

V

Chemical speciation modelling of carbonated steel slag

CEN/TS14429

CEN/TS14405Percolation



Controlling phase missing

Ca and Zn leaching description and partitioning


1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

1.0E+01

1.0E+02

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

Co

ncen

trati

on

(m

ol/

l)

[Ca+2] as function of pH

Steel slag Carbonated TS14429

Model description L/S=10

Steelslag Carbonated TS14405

Model prediction L/S=0.2

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

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

Co

nce

ntr

ati

on

(m

ol/

l)

Partitioning liquid-solid, [Ca+2]

FreePOM-boundFeOxideEttringiteAA_2CaO_Al2O3_SiO2_8H2O[s]AA_2CaO_Fe2O3_SiO2_8H2O[s]AA_3CaO_Al2O3_6H2O[s]AA_3CaO_Fe2O3_CaCO3_11H2O[s]AA_CalciteAA_Tobermorite-Ibeta-TCPCa2V2O7Laumontite

1.0E-10

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

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

Co

ncen

trati

on

(m

ol/

l)

pH

[Zn+2] as function of pH

1.0E-11

1.0E-10

1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

1.0E-04

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

Co

nce

ntr

ati

on

(m

ol/

l)

pH

Partitioning liquid-solid, [Zn+2]

Free

DOC-bound

POM-bound

FeOxide

ZnSiO3

Mo and V leaching description and partitioning


1.0E-09

1.0E-08

1.0E-07

1.0E-06

1.0E-05

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

Co

nce

ntr

ati

on

(m

ol/

l)

[MoO4-2] as function of pH

1.0E-08

1.0E-07

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

Co

ncen

trati

on

(m

ol/

l)

Partitioning liquid-solid, [MoO4-2]

Free

POM-bound

FeOxide

Fe2[MoO4]3[1]

PbMoO4[c]

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

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

Co

ncen

trati

on

(m

ol/

l)

pH

[VO2+] as function of pH

Steel slag Carbonated TS14429


Steelslag Carbonated TS14405


1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

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

Co

ncen

trati

on

(m

ol/

l)

pH

Partitioning liquid-solid, [VO2+]

Free POM-bound

FeOxide Ettringite

Ca2V2O7 Fe_Vanadate

Pb2V2O7

Solubility control for V at pH10 -11 and L/S 0.2 - 10

Mo largely mobile at pH 10-11 –wash out

Why is speciation and partitioning important?

- The chemical form of elements dictates their potential environmental risk

- Whether Cr is present as chromate, Cr III or Cr-DOC complex has significant consequences for the actual impact

- Chromate (Cr VI) generally present in coal fly ash at pH > 8 is more toxic than Cr III

- Cr III – DOC complex is almost as mobile as chromate and may travel relatively fast through soil. The two forms should not be confused.

- DOC complexation of metals is important for their ecotoxicity as many organisms are insensitive to DOC complexed metals

- Understanding speciation allows focussed material management


Processes in a Road Base Application - definitions

Road shoulder, soil

Road stabilisation material (e.g.

alternative construction material)Precipitation

Physical factors:

Permeability

Particle size

Porosity

Chemical factors:

pH

Organic matterBuffer capacity

RedoxChemical form (speciation)

Soluble salts

Transport

mechanisms:

Surface run-off

Percolation

Chemical

mechanisms:

Solubility control

Adsorption

Dispersion

Groundwater flow

Release scenario or source term description

(producer)

Impact assessment (regulator)

= Intended useO2CO2

Conditions during intended use


0.001

0.01

0.1

1

10

100

0.01 0.1 1 10 100

L/S

Cr

(mg

/k

g)

100

1000

10000

0.01 0.1 1 10 100

L/S

Cl

(mg

/k

g)

Prediction leachate quality taking preferential flow into account (80% stagnant- dual porosity model)

10010000

0.01 100

L/S

Landgraaf kolomtest

Model praktijk

Availability

Model kolomtest

Cd affected by substantially reduced Cl release, other metals not influenced (solubility controlled). Cl substantially reduced by preferential flow

0.01

0.1

1

10

100

1000

0.01 0.1 1 10 100

L/S

Cu

(m

g/k

g)

0.001

0.01

0.1

1

10

100

0.01 0.1 1 10 100

L/S

Cd

(m

g/k

g)


Impact Evaluation and Criteria Development

soil: unsaturated

zone

saturated zone (groundwater

transport)

Material

(e.g.,

aggegate)

possible liner (e.g., road)

source term

pathpoint of compliance (object)

Depending on the modeled groundwater quality at

the POC (which might be chosen anywhere), limits

to the release of the construction products might

be adjusted such that the product eventually

complies with the groundwater limit value at the

POC.

Time

Co

ncen

tra

tio

n.

at

PO

C

Groundwater

limit value

Time

Co

ncen

tra

tio

n.

at

PO

C

Groundwater

limit value

POC = point of compliance

Approach with POC in groundwater applied for EU LFD, Dutch BMD and Dutch SQD


Conclusions

A limited set of proper characterisation tests suffices to describe release behaviour from materials and products in a variety of applications

Harmonisation and horizontal standardisation is possible

Significant progress in understanding release controlling processes has been made

Test results can not be compared directly with water quality criteria, as mimicking the field in the lab is generally not possible.

Many substances are solubility controlled, thus providing a good understanding of effects at longer term.

Highly soluble substances are generally most sensitive from an impact assessment perspective (initial peak concentrations).

The multi-element multi-phase chemical reaction transport modelling is a challenge, but a highly rewarding one, when the behaviour of steel slag in laboratory tests can be described.


Recommendations

Emphasize release based judgment as opposed to content based judgment for environmental impact purposes

Bring together more data on steel slag leaching to be able to define the bandwidth of release behaviour

Generate information where gaps are identified

Steel slag release behaviour is process related and thus sharing test data at global scale makes a lot of sense

Develop benchmark characterisation data for steel slag and where needed subdivided for specific steel slag types - LeachXS Lite (free) can provided such service


Thank you for your attention

Questions?


Documents

Harmonisation of leaching test methods in support of EU ......CEN/TS 14997 Chemical speciation aspects Time dependent aspects of release Same as granular + Standardisation: CEN/TC292,