Slags, ferrous metal, blast furnace

Additional information on environmental fate and behaviour

Administrative data

Endpoint:

additional information on environmental fate and behaviour

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-guideline study based on scientific principles

Data source

Reference

Reference 1

Reference Type:

review article or handbook

Title:

Unnamed

Year:

1991

Reference 2

Reference Type:

review article or handbook

Title:

Unnamed

Year:

1992

Materials and methods

Principles of method if other than guideline:

2 different lysimeter experiments and field research

GLP compliance:

no

Type of study / information:

Compilation of several experiments with laboratory (ordinary laboratory and large scale) lysimeters and road lysimeters.

Test material

Test material information

Constituent 1

Reference substance name:

Slags, ferrous metal, blast furnace

EC Number:

266-002-0

EC Name:

Slags, ferrous metal, blast furnace

Cas Number:

65996-69-2

Molecular formula:

~ Al(n)Ca(m)Mg(o)Si(p)O(3n/2+m+o+2p)

IUPAC Name:

Aluminium-Calcium-Magnesium-Silicium oxide equivalent

Details on test material:

Marketed slag used as test material

Results and discussion

Any other information on results incl. tables

The study was conducted to examine the effects of slag on pH and on the concentrations of ions (Al, Ca, SO₄) in different soils and to determine the influence of the study dimensions on the results of leaching experiments. It became obvious that the dimension (small-medium-large size) of experiments is an important factor. In general, small size experiments mirror extreme situations closely related to worst case scenarios. The simulation experiments in the environment reflect the realistic conditions but are very difficult to perform, and they suffer from the limited influence of the experimentator on the experimental conditions.

Analytical information on leachates of ABS, sandy soil and soil containing clay (leaching method DIN 38414 DEV S4)

ABS sandy soil loamy soil

pH (DIN 38404) 10.9 5.2* 7.5*

Al mg/l 0.65 0.45 0.22

Ca mg/l 82 5 13

Cd mg/l < 0.0001 0.0001 0.0001

Cr mg/l < 0.001 0.001 0.001

Cu mg/l < 0.001 0.003 < 0.001

Fe mg/l < 0.01 0.39 0.04

Mg mg/l 0.5 0.3 1.0

Pb mg/l < 0.001 0.002 < 0.001

Zn mg/l < 0.01 0.08 0.17

SO42¯ mg/l 16.0 4.0 3.0

pH determined according to DIN 38404

* determination in CaCl2 solution as a suspension There was no relevant difference between leachtes of ABS and soils

Applicant's summary and conclusion

Conclusions:

Small and large scale lysimeter studies in the laboratory and large scale road lysimeter experiments suggest that slags can be used in road construction as an environmentally friendly material.

Executive summary:

Small and large scale lysimeter studies in the laboratory and large scale road lysimeter experiments suggest that slags can be used in road construction as an environmentally friendly material. Soil conditions influence the applicability of slags as road construction material. In general, a clay layer under the slag will be an effective buffer to diminish leaching of Al-, Ca-, and SO₄-ions.

Leakage depends on the sum of water/rain draining the street. The smaller the amount of precipitation, the lesser the leaching.

Scale of experiments influences outcome of leaching experiments. Large-scale simulation studies better reflect environmental conditions than small-scale laboratory leaching. Environmental effects of slag in the environment are certainly less than these predicted from small-scale laboratory leaching experiments.

The authors suggest that lysimeter studies shall be chosen in large scale to give a more realistic insight in the environmental behavior of slags (FEhS (Bialucha, Geiseler and Degro) 1991, 1992).