PROCESS FOR THE PRODUCTION OF A PGM-ENRICHED ALLOY

Abstract

A gas lance which can be used in a process of any one of the preceding claims, said gas lance comprising or consisting of a rod having inner channels along its length axis, wherein the rod is made of a non-oxidizable ceramic material having a melting point above 1800 C. The gas lance can be used in a pyrometallurgical process for the production of a PGM-enriched alloy.

Claims

1. A process for the production of a PGM-enriched alloy comprising at least one PGM selected from the group consisting of platinum, palladium and rhodium, the process comprising the steps: (1) providing a PGM collector alloy comprising collector metal and one or more PGMs selected from the group consisting of platinum, palladium and rhodium, (2) providing a material capable of forming a slag-like composition when molten, (3) melting the PGM collector alloy and the material capable of forming a slag-like composition when molten within a converter until a multi- or two-phase system of a lower high-density molten mass comprising the molten PGM collector alloy and one or more upper low-density molten masses comprising the molten slag-like composition has formed, (4) contacting an oxidizing gas comprising 0 to 80 vol.-% of inert gas and 20 to 100 vol.-% of oxygen with the lower high-density molten mass obtained in step (3) until it has been converted into a lower high-density molten mass of the PGM-enriched alloy, (5) separating an upper low-density molten slag formed in the course of step (4) from the lower high-density molten mass of the PGM-enriched alloy making use of the difference in density, (6) letting the molten masses separated from one another cool down and solidify, and (7) collecting the solidified PGM-enriched alloy, wherein the contact between the oxidizing gas and the lower high-density molten mass is made by passing the oxidizing gas into the lower high-density molten mass by means of a gas lance the oxidizing gas exhaust of which being immersed into the lower high-density molten mass, wherein the gas lance comprises or consists of a rod having inner channels along its length axis, wherein the rod is made of a non-oxidizable ceramic material having a melting point higher than the temperatures prevailing during step (4), and wherein the oxidizing gas is supplied through at least one of said inner channels.

2. The process of claim 1, wherein the PGM-enriched alloy comprises >0 to 60 wt.-% of iron and 20 to <100 wt.-% of the one or more PGMs.

3. The process of claim 1, wherein the PGM collector alloy provided in step (1) comprises 30 to 95 wt.-% of iron and 2 to 15 wt.-% of one or more PGMs selected from the group consisting of platinum, palladium and rhodium.

4. The process of claim 1, wherein the molten slag-like composition comprises or consists of 40 to 90 wt.-% of magnesium oxide and/or calcium oxide, 10 to 60 wt.-% of silicon dioxide, 0 to 20 wt.-% of iron oxide, 0 to 10 wt.-% of sodium oxide, 0 to 10 wt.-% of boron oxide, and 0 to 2 wt.-% of aluminum oxide.

5. The process of claim 4, wherein (i) the PGM collector alloy comprises 0 to 4 wt.-% of silicon and wherein the the molten slag-like composition comprises 40 to 60 wt.-% of magnesium oxide and/or calcium oxide and 40 to 60 wt.-% of silicon dioxide or (ii) wherein the PGM collector alloy comprises >4 to 15 wt.-% of silicon and wherein the the molten slag-like composition comprises 60 to 90 wt.-% of magnesium oxide and/or calcium oxide and 10 to 40 wt.-% of silicon dioxide.

6. The process of claim 1, wherein the PGM collector alloy and the material capable of forming a slag-like composition when molten may be melted in a weight ratio of 1:0.2 to 1.

7. The process of claim 1, wherein the temperature of the converter contents is raised to 1200 to 1800 C.

8. The process of claim 1, wherein the contacting with the oxidizing gas takes 1 to 5 hours.

9. The process of claim 1, wherein the immersion depth of the oxidizing gas exhaust into the lower high-density molten mass is in the range of from >0 to 10 cm.

10. The process of claim 1, wherein the melting point is above 1800 C.

11. The process of claim 1, wherein the gas lance takes a non-horizontal orientation during the oxidizing gas supply of step (4).

12. The process of claim 1, wherein the ceramic material is selected from the group consisting of aluminum oxide, zirconium oxide, titanium dioxide, magnesium oxide, zinc oxide and aluminum titanate.

13. The process of claim 1, wherein (i) the oxidizing gas is supplied (i) through all inner channels in downward direction or (ii) only through the central inner channel while at the same time cooling gas is supplied through the other inner channels or (iii) through two or more central inner channels while at the same time cooling gas is supplied in downward direction through the other inner channels.

14. The process of claim 13, wherein the cooling gas is air.

15. A gas lance which can be used in a process of any one of the preceding claims, said gas lance comprising or consisting of a rod having inner channels along its length axis, wherein the rod is made of a non-oxidizable ceramic material having a melting point above 1800 C.

Description

[0067] The invention comprises the following embodiments: [0068] 1. A process for the production of a PGM-enriched alloy comprising at least one PGM selected from the group consisting of platinum, palladium and rhodium, the process comprising the steps: [0069] (1) providing a PGM collector alloy comprising collector metal and one or more PGMs selected from the group consisting of platinum, palladium and rhodium, [0070] (2) providing a material capable of forming a slag-like composition when molten, [0071] (3) melting the PGM collector alloy and the material capable of forming a slag-like composition when molten within a converter until a multi- or two-phase system of a lower high-density molten mass comprising the molten PGM collector alloy and one or more upper low-density molten masses comprising the molten slag-like composition has formed, [0072] (4) contacting an oxidizing gas comprising 0 to 80 vol.-% of inert gas and 20 to 100 vol.-% of oxygen with the lower high-density molten mass obtained in step (3) until it has been converted into a lower high-density molten mass of the PGM-enriched alloy, [0073] (5) separating an upper low-density molten slag formed in the course of step (4) from the lower high-density molten mass of the PGM-enriched alloy making use of the difference in density, [0074] (6) letting the molten masses separated from one another cool down and solidify, and [0075] (7) collecting the solidified PGM-enriched alloy,
wherein the contact between the oxidizing gas and the lower high-density molten mass is made by passing the oxidizing gas into the lower high-density molten mass by means of a gas lance the oxidizing gas exhaust of which being immersed into the lower high-density molten mass,
wherein the gas lance comprises or consists of a rod having inner channels along its length axis,
wherein the rod is made of a non-oxidizable ceramic material having a melting point higher than the temperatures prevailing during step (4), and
wherein the oxidizing gas is supplied through at least one of said inner channels. [0076] 2. The process of embodiment 1, wherein the PGM-enriched alloy comprises >0 to 60 wt.-% of iron and 20 to <100 wt.-% of the one or more PGMs. [0077] 3. The process of embodiment 1 or 2, wherein the PGM collector alloy provided in step (1) comprises 30 to 95 wt.-% of iron and 2 to 15 wt.-% of one or more PGMs selected from the group consisting of platinum, palladium and rhodium. [0078] 4. The process of any one of the preceding embodiments, wherein the molten slag-like composition comprises or consists of 40 to 90 wt.-% of magnesium oxide and/or calcium oxide, 10 to 60 wt.-% of silicon dioxide, 0 to 20 wt.-% of iron oxide, 0 to 10 wt. % of sodium oxide, 0 to 10 wt.-% of boron oxide, and 0 to 2 wt.-% of aluminum oxide. [0079] 5. The process of embodiment 4, wherein (i) the PGM collector alloy comprises 0 to 4 wt.-% of silicon and wherein the the molten slag-like composition comprises 40 to 60 wt.-% of magnesium oxide and/or calcium oxide and 40 to 60 wt.-% of silicon dioxide or (ii) wherein the PGM collector alloy comprises >4 to 15 wt.-% of silicon and wherein the the molten slag-like composition comprises 60 to 90 wt.-% of magnesium oxide and/or calcium oxide and 10 to 40 wt.-% of silicon dioxide. [0080] 6. The process of any one of the preceding embodiments, wherein the PGM collector alloy and the material capable of forming a slag-like composition when molten may be melted in a weight ratio of 1:0.2 to 1. [0081] 7. The process of any one of the preceding embodiments, wherein the temperature of the converter contents is raised to 1200 to 1800 C. [0082] 8. The process of any one of the preceding embodiments, wherein the contacting with the oxidizing gas takes 1 to 5 hours. [0083] 9. The process of any one of the preceding embodiments, wherein the immersion depth of the oxidizing gas exhaust into the lower high-density molten mass is in the range of from >0 to 10 cm. [0084] 10. The process of any one of the preceding embodiments, wherein the melting point is above 1800 C. [0085] 11. The process of any one of the preceding embodiments, wherein the gas lance takes a non-horizontal orientation during the oxidizing gas supply of step (4). [0086] 12. The process of any one of the preceding embodiments, wherein the ceramic material is selected from the group consisting of aluminum oxide, zirconium oxide, titanium dioxide, magnesium oxide, zinc oxide and aluminum titanate. [0087] 13. The process of any one of the preceding embodiments, wherein (i) the oxidizing gas is supplied (i) through all inner channels in downward direction or (ii) only through the central inner channel while at the same time cooling gas is supplied through the other inner channels or (iii) through two or more central inner channels while at the same time cooling gas is supplied in downward direction through the other inner channels. [0088] 14. The process of embodiment 13, wherein the cooling gas is air. [0089] 15. A gas lance which can be used in a process of any one of the preceding claims, said gas lance comprising or consisting of a rod having inner channels along its length axis, wherein the rod is made of a non-oxidizable ceramic material having a melting point above 1800 C.

EXAMPLE

[0090] A premix of 500 kg of a PGM collector alloy comprising 47 wt.-% of iron, 14.1 wt.-% of nickel, 8.1 wt.-% of silicon, 4.6 wt.-% of palladium, 3.2 wt.-% of chromium, 2.5 wt.-% of titanium, 2.2 wt.-% of platinum, 1.8 wt.-% of manganese, 0.6 wt.-% of rhodium and 0.9 wt.-% of copper, 123 kg of calcium oxide, 75 kg of silicon dioxide, 15 kg of sodium carbonate and 15 kg of borax was portionwise introduced into an already 1500 C. hot cylindrical natural gas-heated furnace and further heated to 1700 C. After a melting time of 10 hours a two-phase system of a lower high-density molten mass comprising the PGM collector alloy and an upper low-density molten mass comprising a slag-like composition was formed. Oxygen was introduced into the lower high-density molten mass via the exhaust of an air-cooled alumina ceramic gas lance with an oxygen flow of 900 l/min.

[0091] The air-cooled gas lance was comprised of a 1.70 meters long circular rod of alumina ceramic, the rod having a diameter of 5 cm and having a central inner circular channel for the oxygen gas supply. The central inner channel was equidistantly surrounded by a first ring of 6 inner circular channels and a second ring of 12 inner circular channels, said 18 inner circular channels serving as cooling air supply. All 19 inner circular channels had a diameter of 3 mm. Air-cooling was performed with a total air flow of 2500 l of air of 20 C. per minute.

[0092] After 2.5 hours the oxygen introduction was stopped and the gas lance was removed. The upper low-density molten mass was poured into cast iron slag pots in order to cool down and solidify. The lower high-density molten mass was then poured into graphite molds in order to cool down and solidify. After solidification and cooling down to ambient temperature both materials were analyzed by XRF.

Results:

[0093] 1. The PGM enriched alloy comprised 16 wt.-% of iron, 53 wt.-% of nickel, 3 wt.-% of copper and 28 wt.-% of PGMs (platinum plus palladium plus rhodium). [0094] 2. The slag comprised 47 wt.-ppm of PGMs, 31 wt.-% of iron and 1 wt.-% of nickel. [0095] 3. The gas lance showed some damage but could be used for the same procedure a second time.