METHOD FOR BREAKING DOWN A MIXTURE OF SOLID PARTICLES COMPRISING RUTHENIUM

Abstract

A method for breaking down a mixture, which is present in the form of solid particles, consisting of: (A) 0 to 99% by weight of metallic ruthenium, (B) 0 to 50% by weight of at least one element other than ruthenium, which is present in elementary form, selected from the group of elements of the atomic numbers 13, 21-30, 39-42, 45-52, and 72-83, (C) 0 to 99% by weight of ruthenium oxide, (D) 0 to 70% by weight of at least one solid element oxide other than ruthenium, (E) 0 to 30% by weight of at least one inorganic substance other than (A) to (D), and (F) 0 to 3% by weight of at least one organic substance, wherein the sum of the % by weight of the compounds (A) to (F) is 100% by weight and the ruthenium content of the mixture is 2 to 99% by weight, and wherein the method comprises the steps of: (1) optionally mixing said mixture with alkali carbonate by forming a blend, (2) alkaline oxidizing breakdown of the mixture or of the blend, respectively, formed in optional step (1) into molten potassium hydroxide using a gaseous oxidizing agent selected from the group consisting of air, oxygen, and air/oxygen mixtures, and without use of nitrate, and (3) cooling down the breakdown material formed in step (2) to a temperature below its solidification temperature, wherein the gaseous oxidizing agent is introduced into the melt in step (2).

Claims

1. A method for breaking down a mixture, which is present in the form of solid particles, the mixture consisting of: (A) 0 to 99% by weight of metallic ruthenium, (B) 0 to 50% by weight of at least one element other than ruthenium, which is present in elementary form, selected from the group of elements of the atomic numbers 13, 21-30, 39-42, 45-52, and 72-83, (C) 0 to 99% by weight of ruthenium oxide, (D) 0 to 70% by weight of at least one solid element oxide other than ruthenium, (E) 0 to 30% by weight of at least one inorganic substance other than (A) to (D), and (F) 0 to 3% by weight of at least one organic substance, wherein the sum of the % by weight of the compounds (A) to (F) is 100% by weight and the ruthenium content of the mixture is 2 to 99% by weight, and wherein the method comprises the steps of: (1) optionally mixing said mixture with alkali carbonate by forming a blend, (2) alkaline oxidizing breakdown of the mixture or of the blend, respectively, formed in optional step (1) into molten potassium hydroxide using a gaseous oxidizing agent selected from the group consisting of air, oxygen, and air/oxygen mixtures, and without use of nitrate, and (3) cooling down the breakdown material formed in step (2) to a temperature below its solidification temperature, wherein the gaseous oxidizing agent is introduced into the melt in step (2).

2. The method according to claim 1, wherein step (1) is realized with a quantity of 20 to 1000 kg of the mixture.

3. The method according to claim 1, wherein step (1) is realized with a weight ratio of 1 part by weight of mixture to 0.05 to 0.5 parts by weight of alkali carbonate.

4. The method according to claim 1, wherein the mixture, which is to be broken down, is an ore concentrate or a mixture of a plurality of different ore concentrates of an ore dressing and/or a residue or a mixture of a plurality of different residues, each containing ruthenium, of a precious metal preparation.

5. The method according to claim 1, wherein the mixture, which is to be broken down, is characterized by a particle size D10 in the range of 0.5 to 1 μm, and D50 in the range of 2 to 10 μm of the solid particles, of which it consists.

6. The method according to claim 1, wherein in addition to the gaseous oxidation agent, an oxidation agent other than nitrate is also not used or added.

7. The method according to claim 1, wherein the weight ratio of mixture, which is to be broken down, and molten potassium hydroxide used in step (2) is 1:2 to 1:5.

8. The method according to claim 1, wherein in step (2) no further substances are used or added in addition to the mixture, which is to be broken down, or the blend, respectively, potassium hydroxide and the gaseous oxidation agent.

9. The method according to claim 1, wherein step (2) comprises the addition of the mixture or of the blend, respectively, which is to be broken down, into a previously produced potassium hydroxide melt.

10. The method according to claim 9, wherein the potassium hydroxide melt has a temperature in the range of 400 to 800° C. during the addition.

11. The method according to claim 9, wherein the molten material created upon completion of the addition is further mixed.

12. The method according to claim 1, wherein a step (4) comprising the dissolution of the cooled-down and solidified broken down material in water follows upon completion of step (3).

13. The method according to claim 2, wherein step (1) is realized with a weight ratio of 1 part by weight of mixture to 0.05 to 0.5 parts by weight of alkali carbonate.

14. The method according to claim 10, wherein the molten material created upon completion of the addition is further mixed.

Description

EXAMPLES

Example 1

[0040] 400 kg of potassium hydroxide were placed into a crucible and were melted at 550° C. 130 kg of an ore concentrate in the form of a mixture of solid particles (D10=0.47 μm, D50=8.55 μm; composition according to X-ray fluorescence (RFA), each in % by weight: 6% Ru, 26% Pt, 12% Pd, 4% Rh, 1% Ir, 3% Se, 3% Fe) were added by stirring for a time period of 3.5 hours. The temperature was then increased to 620° C. and was maintained for a time period of 5 hours under continuous stirring. 152 cubic meters of oxygen were meanwhile introduced into the melt by means of a stainless steel gas lance immersed into the melt. The melt was subsequently poured into melting vats. After the cool-down to 20° C., a total of 600 liters of water was added to the solidified melt and was suspended for 5 hours.

[0041] The obtained aqueous suspension was allowed to settle and the excess aqueous solution obtained thereby was decanted and analyzed.

[0042] The recovery rate for ruthenium was 98% (calculated from the ruthenium content of the aqueous solution with reference to the used mixture determined by means of inductively coupled plasma emission (ICP)).

Example 2

[0043] 25 g of potassium hydroxide were melted in a crucible at 570° C. By stirring, a mixture of 10 g of Ru powder and 0.5 g of RuO.sub.2 powder were added in portions by stirring. Stirring was subsequently continued at 570° C. for 5 hours, accompanied by a four-hour introduction of a total of 12 liters of oxygen into the melt via a stainless steel gas introduction tube. Cool-down then took place. After the melt had cooled, the residue was dissolved in 150 ml of water and was filtrated subsequently. The dissolution residue was dried and weighed (0.01 g). The aqueous solution was analyzed.

[0044] The recovery rate for the ruthenium was 98.79% (calculated from the ruthenium content of the aqueous solution with reference to the used mixture determined by means of inductively coupled plasma emission (ICP)).