PROCESS FOR THE PRODUCTION OF A PGM-ENRICHED ALLOY

Abstract

A process for the production of a PGM-enriched alloy comprising 0 to 60 wt.-% of iron and 20 to 99 wt.-% of one or more PGMs selected from the group consisting of platinum, palladium and rhodium, the process comprising the steps of (1) providing a PGM collector alloy comprising 30 to 95 wt.-% of iron, less than 1 wt.-% of sulfur and 2 to 15 wt.-% of one or more PGMs selected from the group consisting of platinum, palladium and rhodium, (2) providing a copper- and sulfur-free material capable of forming a slag-like composition when molten, wherein the molten slag-like composition comprises 40 to 90 wt.-% of magnesium oxide and/or calcium oxide and 10 to 60 wt.-% of silicon dioxide, (3) melting the PGM collector alloy and the material capable of forming a slag-like composition when molten in a weight ratio of 1:0.2 to 1 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.

Claims

1. A process for the production of a PGM-enriched alloy comprising 0 to 60 wt.-% of iron and 20 to 99 wt.-% of one or more PGMs selected from the group consisting of platinum, palladium and rhodium, the process comprising the steps: (1) providing a PGM collector alloy comprising 30 to 95 wt.-% of iron, less than 1 wt.-% of sulfur and 2 to 15 wt.-% of one or more PGMs selected from the group consisting of platinum, palladium and rhodium, (2) providing a copper- and sulfur-free material capable of forming a slag-like composition when molten, wherein the molten slag-like composition comprises 40 to 90 wt.-% of magnesium oxide and/or calcium oxide and 10 to 60 wt.-% of silicon dioxide, (3) melting the PGM collector alloy and the material capable of forming a slag-like composition when molten in a weight ratio of 1:0.2 to 1 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.

2. The process of claim 1, wherein the PGM-enriched alloy comprises or consists of 0 to 45 wt.-% of iron and 30 to 99 wt.-% of the one or more PGMs, 0 to 60 wt.-% of nickel, 0 to 5 wt.-% of copper, and 0 to 10 wt.-% of one or more other elements.

3. The process of claim 1, wherein the PGM-enriched alloy comprises or consists of 0 to 20 wt.-% of iron, 40 to 90 wt.-% of the one or more PGMs, 0 to 60 wt.-% of nickel, 0 to 5 wt.-% of copper and 0 to 3 wt.-% of the one or more other elements.

4. The process of claim 1, wherein the PGM collector alloy provided in step (1) comprises 40 to 70 wt.-% of iron, 0 to 20 wt.-% of nickel, less than 1 wt.-% of sulfur and 5 to 15 wt.-% of the one or more PGMs.

5. The process of claim 1, wherein the PGM collector alloy comprises no more than 4 wt.-% of copper.

6. The process of claim 1, wherein the PGM collector alloy comprises or consists of: 30 to 95 wt.-% of iron, 0 to 20 wt.-% of nickel, 0 to <1 wt.-% of sulfur, 2 to 15 wt.-% of the one or more PGMs, 0 to 4 wt.-% of copper, and 0 to 30 wt.-% of one or more other elements.

7. The process of claim 1, wherein the PGM collector alloy comprises or consists of: 40 to 70 wt.-% of iron, 0 to 15 wt.-% of nickel, 0 to <1 wt.-% of sulfur, 5 to 15 wt.-% of the one or more PGMs, 0 to 1 wt.-% of copper, and 0 to 20 wt.-% of one or more other elements.

8. 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 20 wt.-% of sodium oxide, 0 to 20 wt.-% of boron oxide, and 0 to 2 wt.-% of aluminum oxide.

9. 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 wt.-% of iron oxide, 0 to 10 wt.-% of sodium oxide, 0 to 10 wt.-% of boron oxide, and 0 wt.-% of aluminum oxide.

10. The process of claim 1, wherein the PGM collector alloy comprises 0 to 4 wt.-% of silicon and wherein 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.

11. The process of claim 1, wherein the PGM collector alloy comprises >4 to 15 wt.-% of silicon and wherein 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.

12. The process of claim 1, wherein the PGM collector alloy and the material capable of forming a slag-like composition when molten are melted in a weight ratio of 1:0.2 to 0.8 or 1:0.2 to 0.6.

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

14. The process of claim 1, wherein the contact between the oxidizing gas and the lower high-density molten mass is made by passing or bubbling the gas through the lower high-density molten mass from the bottom of the converter and/or by means of a gas lance the exhaust of which being immersed into the lower high-density molten mass.

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

Description

[0071] The invention comprises the following embodiments:

[0072] 1. A process for the production of a PGM-enriched alloy comprising 0 to 60 wt.-% of iron and 20 to 99 wt.-% of one or more PGMs selected from the group consisting of platinum, palladium and rhodium, the process comprising the steps: [0073] (1) providing a PGM collector alloy comprising 30 to 95 wt.-% of iron, less than 1 wt.-% of sulfur and 2 to 15 wt.-% of one or more PGMs selected from the group consisting of platinum, palladium and rhodium, [0074] (2) providing a copper- and sulfur-free material capable of forming a slag-like composition when molten, wherein the molten slag-like composition comprises 40 to 90 wt.-% of magnesium oxide and/or calcium oxide and 10 to 60 wt.-% of silicon dioxide, [0075] (3) melting the PGM collector alloy and the material capable of forming a slag-like composition when molten in a weight ratio of 1:0.2 to 1 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, [0076] (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, [0077] (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, [0078] (6) letting the molten masses separated from one another cool down and solidify, and [0079] (7) collecting the solidified PGM-enriched alloy.

[0080] 2. The process of embodiment 1, wherein the PGM-enriched alloy comprises or consists of 0 to 45 wt.-% of iron and 30 to 99 wt.-% of the one or more PGMs, 0 to 60 wt.-% of nickel, 0 to 5 wt.-% of copper, and 0 to 10 wt.-% of one or more other elements.

[0081] 3. The process of embodiment 1, wherein the PGM-enriched alloy comprises or consists of 0 to 20 wt.-% of iron, 40 to 90 wt.-% of the one or more PGMs, 0 to 60 wt.-% of nickel, 0 to 5 wt.-% of copper and 0 to 3 wt.-% of the one or more other elements.

[0082] 4. The process of any one of the preceding embodiments, wherein the PGM collector alloy provided in step (1) comprises 40 to 70 wt.-% of iron, 0 to 20 wt.-% of nickel, less than 1 wt.-% of sulfur and 5 to 15 wt.-% of the one or more PGMs.

[0083] 5. The process of any one of the preceding embodiments, wherein the PGM collector alloy comprises no more than 4 wt.-% of copper.

[0084] 6. The process of any one of embodiments 1 to 3, wherein the PGM collector alloy comprises or consists of: [0085] 30 to 95 wt.-% of iron, [0086] 0 to 20 wt.-% of nickel, [0087] 0 to <1 wt.-% of sulfur, [0088] 2 to 15 wt.-% of the one or more PGMs, [0089] 0 to 4 wt.-% of copper, and [0090] 0 to 30 wt.-% of one or more other elements.

[0091] 7. The process of any one of embodiments 1 to 3, wherein the PGM collector alloy comprises or consists of: [0092] 40 to 70 wt.-% of iron, [0093] 0 to 15 wt.-% of nickel, [0094] 0 to <1 wt.-% of sulfur, [0095] 5 to 15 wt.-% of the one or more PGMs, [0096] 0 to 1 wt.-% of copper, and [0097] 0 to 20 wt.-% of one or more other elements.

[0098] 8. The process of any one of the preceding embodiments, wherein the molten slag-like composition comprises or consists of: [0099] 40 to 90 wt.-% of magnesium oxide and/or calcium oxide, [0100] 10 to 60 wt.-% of silicon dioxide, [0101] 0 to 20 wt.-% of iron oxide, [0102] 0 to 20 wt.-% of sodium oxide, [0103] 0 to 20 wt.-% of boron oxide, and [0104] 0 to 2 wt.-% of aluminum oxide.

[0105] 9. The process of any one of embodiments 1 to 7, wherein the molten slag-like composition comprises or consists of: [0106] 40 to 90 wt.-% of magnesium oxide and/or calcium oxide, [0107] 10 to 60 wt.-% of silicon dioxide, [0108] 0 wt.-% of iron oxide, [0109] 0 to 10 wt.-% of sodium oxide, [0110] 0 to 10 wt.-% of boron oxide, and [0111] 0 wt.-% of aluminum oxide.

[0112] 10. The process of any one of the preceding embodiments, wherein the PGM collector alloy comprises 0 to 4 wt.-% of silicon and wherein 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.

[0113] 11. The process of any one of embodiments 1 to 9, wherein the PGM collector alloy comprises >4 to 15 wt.-% of silicon and wherein 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.

[0114] 12. 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 are melted in a weight ratio of 1:0.2 to 0.8 or 1:0.2 to 0.6.

[0115] 13. The process of any one of the preceding embodiments, wherein the temperature of the converter contents is raised to 1200 to 1800 C.

[0116] 14. The process of any one of the preceding embodiments, wherein the contact between the oxidizing gas and the lower high-density molten mass is made by passing or bubbling the gas through the lower high-density molten mass from the bottom of the converter and/or by means of a gas lance the exhaust of which being immersed into the lower high-density molten mass.

[0117] 15. The process of any one of the preceding embodiments, wherein the contact with the oxidizing gas takes 1 to 5 hours.

EXAMPLES

Example 1

[0118] 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.

[0119] 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 a ceramic pipe with an oxygen flow of 900 l/min. After 2.5 hours the oxygen introduction was stopped. 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.

Examples 2 and 3

[0120] Example 1 was repeated with the difference that the oxygen introduction took 2.75 hours (Example 2) or 3 hours (Example 3).

[0121] The results of the XRF analysis are compiled in Tables 1 and 2. All values are in wt.-%, except the values for the PGM content in the slag which are in wt.-ppm:

TABLE-US-00001 TABLE 1 Composition of the solidified upper low-density mass (slag) Element Example 1 Example 2 Example 3 Fe 29 35 40 Ni 1 1 1 Total PGM 49 47 44

TABLE-US-00002 TABLE 2 Composition of the solidified lower high-density mass (PGM enriched alloy) Element Example 1 Example 2 Example 3 PGM 27 28 34 Fe 20 18 13 Ni 50 51 51