Slimes and sludges, electrolytic refining of tin, lead and silver containing alloy

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

Study period:

10/09/2018-11/10/2018

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

Version / remarks:

July 2001

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Specific details on test material used for the study:

Particle sizes of the sample ranged from powder up to 6 mm, Particles >1 mm were crushed and sieved, so they met the <1 mm requirement of the OECD no 29 guidance.

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

< 0.04 µg/L

Element analysed:

Silver

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

at nominal pH 6

Remarks on result:

other: n=9

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

141 µg/L

Element analysed:

Arsenic

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

at nominal pH 6

Remarks on result:

other: standard deviation: 13 µg/L (n=9)

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

9.8 µg/L

Element analysed:

Copper

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

at nominal pH 6

Remarks on result:

other: Standard deviation 5.8 µg/L (n=9)

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

39.9 µg/L

Element analysed:

Nickel

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

At nominal pH 6

Remarks on result:

other: Standard deviation: 0.3 µg/L (n=9)

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

862 µg/L

Element analysed:

Lead

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

At nominal pH 6

Remarks on result:

other: Standard deviation: 58 (n=9)

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

520 µg/L

Element analysed:

Antimony

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

At nominal pH 6

Remarks on result:

other: Standard deviation: 18 µg/L (n=9)

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

364 µg/L

Element analysed:

Tin

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

At nominal pH 6

Remarks on result:

other: Standard deviation: 70 µug/L (n=9)

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

< 0.04 µg/L

Element analysed:

Silver

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

At nominal pH 8

Remarks on result:

other: n=9

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

74.9

Element analysed:

Arsenic

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

At nominal pH 8

Remarks on result:

other: Standard deviation: 11.8 (n=9)

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Copper

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

At nominal pH 8

Remarks on result:

other: n=9

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

35.6 µg/L

Element analysed:

Nickel

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

At nominal pH 8

Remarks on result:

other: Standard deviation: 0.8 µg/L (n=9)

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

389 µg/L

Element analysed:

Lead

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

At nominal pH 8

Remarks on result:

other: Standard deviation: 52 µg/L (n=9)

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

497 µg/L

Element analysed:

Antimony

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

At nominal pH 8

Remarks on result:

other: Standard deviation: 37 µg/L; (n=9)

Key result

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

30 µg/L

Element analysed:

Tin

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

At nominal pH 8

Remarks on result:

other: Standard deviation 4.3 µg/L (n=9)

Details on results:

Based on the element contents in the test item and the average dissolved element concentrations in the test solutions:
- a release of silver of <0.00016 % of content,
- a release of arsenic of 12 % of content,
- a release of copper of 2.5 % of content,
- a release of nickel of 10 % of content,
- a release of lead of 66 % of content,
- a release of antimony of 7.6 % of content,
- a release of tin of 1.0 % of content
could be calculated at the 24 hours endpoint in test medium at pH 6.

Based on the element contents in the test item and the average dissolved element concentrations in the test solutions:
- a release of silver of <0.00016 % of content,
- a release of arsenic of 6.2 % of content,
- a release of copper of <0.13 % of content,
- a release of nickel of 8.9 % of content,
- a release of lead of 30 % of content,
- a release of antimony of 7.3 % of content,
- a release of tin of 0.081 % of content,
could be calculated at the 24 hours endpoint in test medium at pH 8.

Conclusions:

During this study on Slimes and sludges, electrolytic tin refining at a loading of 100 mg/L, it was shown that:
- For silver, an average concentration of <0.04 μg/L Ag (N = 9) was measured at pH 6 (i.e. <0.00016 % silver release) and <0.04 μg/L Ag (N = 9) at pH 8 (i.e., <0.00016 % silver release),
- For arsenic, an average concentration of 141 μg/L As (CVoverall = 9 %; N = 9) was measured at pH 6 (i.e. 12 % arsenic release) and 74.9 μg/L As (CVoverall = 16 %; N = 9) at pH 8 (i.e., 6.2 % arsenic release),
- For copper, an average concentration of 9.8 μg/L Cu (CVoverall = 59 %; N = 9) was measured at pH 6 (i.e. 2.5 % copper release) and <0.5 μg/L Cu (N = 9) at pH 8 (i.e., <0.13 % copper release),
- For nickel, an average concentration of 39.9 μg/L Ni (CVoverall = 1 %; N = 9) was measured at pH 6 (i.e. 10 % nickel release) and 35.6 μg/L Ni (CVoverall = 2 %; N = 9) at pH 8 (i.e., 8.9 % nickel release),
- For lead, an average concentration of 862 μg/L Pb (CVoverall = 7 %; N = 9) was measured at pH 6 (i.e. 66 % lead release) and 389 μg/L Pb (CVoverall = 13 %; N = 9) at pH 8 (i.e., 30 % lead release),
- For antimony, an average concentration of 520 μg/L Sb (CVoverall = 4 %; N = 9) was measured at pH 6 (i.e. 7.6 % antimony release) and 497 μg/L Sb (CVoverall = 7 %; N = 9) at pH 8 (i.e., 7.3 % antimony release),
- For tin, an average concentration of 364 μg/L Sn (CVoverall = 19 %; N = 9) was measured at pH 6 (i.e. 1.0 % tin release) and 30.0 μg/L Sn (CVoverall = 14 %; N = 9) at pH 8 (i.e., 0.081 % tin release),
after 24 hours of exposure to the test medium at pH 6 and pH 8, respectively.

Based on the rounded results, of the dissolved element concentrations, we may conclude that nominal pH 6 is the pH where the highest concentrations of arsenic, copper, nickel, lead and tin concentrations were measured. However, for silver and antimony, this study could not identify a significant correlation between pH level and short-term dissolution rate.

Although the pH in the test item shifted vessels to lower values outside the standard test areas (6.0 ± 0.2 and 8.0 ± 0.2), the results can be assumed reliable since the test conditions of the blank control vessels stayed constant during the experiment.

Executive summary:

The objective of this study was to obtain information about the dissolution characteristics of Slimes and sludges, electrolytic tin refining. The pH-dependent extent of dissolution of Slimes and sludges, electrolytic tin refining was tested in standard aqueous solutions at pH 6 (0.5 % CO2-buffering) and pH 8 (air-buffering) for 24 hours at an agitation speed of 100 revolutions per minute (rpm). The extent of the transformation/dissolution was measured as the dissolved silver, arsenic, copper, nickel, lead, antimony and tin concentrations obtained after 24 hours. This study has been performed according to OECD Test Guidance No.29, as laid down in the Study Plan and performed according to the SOPs as established by ECTX. The study was performed at ECTX. Analyses of the concentrations of dissolved silver, arsenic, copper, nickel, lead, antimony and tin, and the determination of the total organic carbon content (TOC) of the test media have been performed at WLN Business B.V. (The Netherlands), the ISO 17025 accredited laboratory, as delegated by ECTX.

The test media at the start of the test and the blank control vessels during the test showed concentrations below or close to the limits of detection of 0.04 μg/L Ag, 0.03 μg/L As, 0.5 μg/L Cu, 0.03 μg/L Ni, 0.6 μg/L Pb, 0.03 μg/L Sb and 0.2 μg/L Sn. The limits of detection were determined as the rounded up values of three times the standard deviation of each element of all blank measurements in this study at pH 6 and pH 8).

For the test at nominal pH 6 at a loading of 100 mg/L Slimes and sludges, electrolytic tin refining, average dissolved concentrations of:

- <0.04 μg/L silver (N = 9),

- 141 ± 13 μg/L arsenic (CVoverall = 9 %; N = 9),

- 9.8 ± 5.8 μg/L copper (CVoverall = 59 %; N = 9),

- 39.9 ± 0.3 μg/L nickel (CVoverall = 1 %; N = 9),

- 862 ± 58 μg/L lead (CVoverall = 7 %; N = 9),

- 520 ± 18 μg/L antimony (CVoverall = 4 %; N = 9),

- 364 ± 70 μg/L tin (CVoverall = 19 %; N = 9),

were found at the 24 hours endpoint.

Based on the element contents in the test item and the average dissolved element concentrations in the test solutions:

- a release of silver of <0.00016 % of content,

- a release of arsenic of 12 % of content,

- a release of copper of 2.5 % of content,

- a release of nickel of 10 % of content,

- a release of lead of 66 % of content,

- a release of antimony of 7.6 % of content,

- a release of tin of 1.0 % of content,

could be calculated at the 24 hours endpoint in test medium at pH 6.

For the test at nominal pH 8 at a loading of 100 mg/L Slimes and sludges, electrolytic tin refining, average dissolved concentrations of:

- <0.04 μg/L silver (N = 9),

- 74.9 ± 11.8 μg/L arsenic (CVoverall = 16 %; N = 9),

- <0.5 μg/L copper (N = 9),

- 35.6 ± 0.8 μg/L nickel (CVoverall = 2 %; N = 9),

- 389 ± 52 μg/L lead (CVoverall = 13 %; N = 9),

- 497 ± 37 μg/L antimony (CVoverall = 7 %; N = 9),

- 30.0 ± 4.3 μg/L tin (CVoverall = 14 %; N = 9),

were found at the 24 hours endpoint.

Based on the element contents in the test item and the average dissolved element concentrations in the test solutions:

- a release of silver of <0.00016 % of content,

- a release of arsenic of 6.2 % of content,

- a release of copper of <0.13 % of content,

- a release of nickel of 8.9 % of content,

- a release of lead of 30 % of content,

- a release of antimony of 7.3 % of content,

- a release of tin of 0.081 % of content,

could be calculated at the 24 hours endpoint in test medium at pH 8.

Based on the results of the experiments we may conclude that nominal “pH 6” is the pH where the highest dissolved arsenic, copper, nickel, lead and tin concentrations were measured. However, for silver and antimony, this study could not identify a significant correlation between pH level and short-term dissolution rate. This dissolution result may be important in the design of the standard 7 days and 28 days transformation/dissolution test to enable appropriate hazard classification categories under EU-CLP and UN-Globally Harmonized System.

Description of key information

During this study on 'Slimes and sludges electrolytic refining of tin, lead and silver containing alloy' (formerly called Slimes and sludges, electrolytic tin refining) at a loading of 100 mg/L, it was shown that:

- For silver, an average concentration of <0.04 μg/L Ag (N = 9) was measured at pH 6 (i.e. <0.00016 % silver release) and <0.04 μg/L Ag (N = 9) at pH 8 (i.e., <0.00016 % silver release),

- For arsenic, an average concentration of 141 μg/L As (CVoverall = 9 %; N = 9) was measured at pH 6 (i.e. 12 % arsenic release) and 74.9 μg/L As (CVoverall = 16 %; N = 9) at pH 8 (i.e., 6.2 % arsenic release),

- For copper, an average concentration of 9.8 μg/L Cu (CVoverall = 59 %; N = 9) was measured at pH 6 (i.e. 2.5 % copper release) and <0.5 μg/L Cu (N = 9) at pH 8 (i.e., <0.13 % copper release),

- For nickel, an average concentration of 39.9 μg/L Ni (CVoverall = 1 %; N = 9) was measured at pH 6 (i.e. 10 % nickel release) and 35.6 μg/L Ni (CVoverall = 2 %; N = 9) at pH 8 (i.e., 8.9 % nickel release),

- For lead, an average concentration of 862 μg/L Pb (CVoverall = 7 %; N = 9) was measured at pH 6 (i.e. 66 % lead release) and 389 μg/L Pb (CVoverall = 13 %; N = 9) at pH 8 (i.e., 30 % lead release),

- For antimony, an average concentration of 520 μg/L Sb (CVoverall = 4 %; N = 9) was measured at pH 6 (i.e. 7.6 % antimony release) and 497 μg/L Sb (CVoverall = 7 %; N = 9) at pH 8 (i.e., 7.3 % antimony release),

- For tin, an average concentration of 364 μg/L Sn (CVoverall = 19 %; N = 9) was measured at pH 6 (i.e. 1.0 % tin release) and 30.0 μg/L Sn (CVoverall = 14 %; N = 9) at pH 8 (i.e., 0.081 % tin release),

after 24 hours of exposure to the test medium at pH 6 and pH 8, respectively.

Based on the rounded results, of the dissolved element concentrations, we may conclude that nominal pH 6 is the pH where the highest concentrations of arsenic, copper, nickel, lead and tin concentrations were measured. However, for silver and antimony, this study could not identify a significant correlation between pH level and short-term dissolution rate.

Although the pH in the test item shifted vessels to lower values outside the standard test areas (6.0 ± 0.2 and 8.0 ± 0.2), the results can be assumed reliable since the test conditions of the blank control vessels stayed constant during the experiment.