Slags, ferromolybdenum-manufg., silicothermic

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

Deviations:

no

GLP compliance:

yes

Type of method:

other: transformation / dissolution

Specific details on test material used for the study:

Preparation of test samples:
Samples were prepared at Sadaci, Langerbruggekaai 13, B-9000 Gent
- approximately 5 kg of course slags (0-14 mm) were dried for 4 hours at 105°C, then sieved through an 8 mm sieve.
- Glass pieces were manually selected (about 280g) and were grinded manually with a mortar and pestle. Sieving was then done with a 1.7 and a 0.85 mm sieve.
- The fraction between 0.85 and 1.7 mm was washed with deionised water and dried for 2 hours at 105°C. Then the fraction was homogenised with a turbula which made the particles smaller, and then passed through 1.0 mm and 0.85 mm sieve.
-The fraction between 0.85 and 1.0 mm was then washed with deionised water.

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

0.7 µg/L

Element analysed:

Mo

Loading of aqueous phase:

100 other: mg test item / L

Incubation duration:

2 h

Test conditions:

pH 6, T = 22 °C

Remarks on result:

other: average of 3 replicates with C.V% = 23

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

0.8 µg/L

Element analysed:

Mo

Loading of aqueous phase:

100 other: mg test item/L

Incubation duration:

6 h

Test conditions:

pH 6, T = 22 °C

Remarks on result:

other: average of 3 replicates with C.V% = 30

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

1.3 µg/L

Element analysed:

Mo

Loading of aqueous phase:

100 other: mg test item / L

Incubation duration:

24 h

Test conditions:

pH 6, T = 22 °C

Remarks on result:

other: average of 3 replicates with C.V.% = 26

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

1.4 µg/L

Element analysed:

Mo

Loading of aqueous phase:

100 other: mg test item / L

Incubation duration:

2 d

Test conditions:

pH 6, T= 22 °C

Remarks on result:

other: average from 3 replicates with C.V% = 27

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

2 µg/L

Element analysed:

Mo

Loading of aqueous phase:

100 other: mg test item / L

Incubation duration:

4 d

Test conditions:

pH 6, T = 22 °C

Remarks on result:

other: average from 3 replicates, with C.V.% = 37

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

3 µg/L

Element analysed:

Mo

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

pH 6, T = 22 °C

Remarks on result:

other: average from 3 replicates, with C.V. % = 62

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.2 µg/L

Element analysed:

Mo

Loading of aqueous phase:

1 other: mg test item /L

Incubation duration:

7 d

Test conditions:

pH 6, T = 22 °C

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.2 µg/L

Element analysed:

Mo

Loading of aqueous phase:

1 other: mg test item / L

Incubation duration:

28 d

Test conditions:

pH 6, T = 22 °C

Details on results:

Only for the 100 mg/L loading, a small amount of molybdenum was measured above detection limits (3 ug/L at 7-days).
For the 1 mg/L loading at 7-day and 28-day endpoints, the Mo concentration was at below the detection limit of 0.2 ug/L.
The raw data were used to calculate the mean (+/- SD) of the measured dissolved Mo concentration per test vessel (100 mg/L loading only). The overall average (+/-SD) of the means of the different test vessels per sampling time was calculated as well. The Coefficient of Variation (C.V.%) = (S.D./mean)*100) was calculated to have an idea of the spread of the results.
Within vessel variations were below 10% at the 7-day endpoints for Mo. The between vessel variation based on the dissolved Mo concentrations however was at all times higher than the maximum target variation of 20%. This is probably due to the heterogeneity in composition and structure of the test material.
Dissolution of Pb, Cu, Al, As, Cr, Fe, Ni and Fluorine were also measured. The concentrations were below the detection limit for all elements except for Cu (0.8 ug/L) for the 100 mg/L loading for the 7-day endpoint. The concentrations were below the detection limit for all elements at the 1-mg/L loading for the 7-day and 28-day endpoints.

Conclusions:

Under the conditions of this test, the dissolution of Mo is 3 ug/L at 100 mg/L loading for the 7-day endpoint, and below the detection limit of 0.2 ug/L at the 1 mg/L loading for the 7-day and 28-day endpoints.
This data shows that FeMo slag is insoluble at 22°C.

This data is also useful for the purpose of acute and chronic environmental classification of FeMo slags. Data on the dissolution of dissolved Mo as well as Cu, Pb, Ni, Fe, Al, As, Cr, and Fluorine are measured.
The results of the 100 mg/L loading for the 7-day endpoint is used for acute classification purposes.
Results show the low dissolution of all the elements measured (

The results of the 1 mg/L loading for the 28-day endpoint is used for the chronic classification purposes. Results show the low dissolution of all the elements measured (concentrations measured were

Description of key information

FeMo slags is a UVCB substance. It is a solid, glass-like, mostly amorphous material, basically consisting of oxides of silicon, aluminium, calcium and iron, which solidifies from a reaction melt when the temperature drops below ca. 1100 - 1600 °C. This material is considered to be insoluble in water, chemically inert and thermally stable up to this melting point. However, specifically in the context of environmental hazard classification, the potential dissolution of FeMo slags in water has been assessed experimentally, subjecting a representative sample to the transformation dissolution protocol (T/Dp; OECD Series on Testing and Assessment No. 29). The test results (see discussion) confirm that FeMo slags are basically insoluble and inert in water.

In addition to this T/Dp study, the substance has also been tested in a bioelution study (in vitro bioaccessibility) in artificial gastric juice. This test and the results are described in the stand-alone document „MoCon read-across concept (human health)“, which is attached to the technical dossier in IUCLID section 13.

 

Additional information

A transformation dissolution test with a representative sample of FeMo slags has been conducted (a 7 day test at a loading of 100 mg/L plus a 7 and 28 day test at a loading of 1 mg/L). The dissolved concentration of a number of elements have been analysed, which are contained in this UVCB material, and the release of which could be of relevance for the environmental classification: Pb, Cu, Al, As, Cr, Fe, Mo, Ni and F. Detection limits were in the µg/L range. At the 1 mg/L loading, the dissolved concentrations of all elements were below the respective detection limits at both after 7 and 28 days. At the high loading of 100 mg/L the concentration of all elements were below the respective detection limits after 7 days except for Mo (3 µg/L) and Cu (0.8 µg/L). Based on these results, no acute or chronic environmental hazard classification results for FeMo slags. The test results confirm that FeMo slags are basically insoluble and inert in water.

In addition to this T/Dp study, the substance has also been tested in a bioelution study (in vitro bioaccessibility) in artificial gastric juice. This test and the results are described in the stand-alone document „MoCon read-across concept (human health)“, which is attached to the technical dossier in IUCLID section 13.