Osaka Refinery, Japan

At present, the countries in the world that use the combined process of metallurgical processing to treat copper anode mud are Finland, Japan, the United States, Russia, Germany, and Canada. For example, the treatment of anode mud in Osaka Refinery in Japan is characterized by high lead sulfate content, and the composition is shown in Table 1. The monthly production of gold is 723kg, silver is 16409kg, selenium is 11113kg, and 碲 998kg.

Table 1 Composition of copper anode slime in Osaka refinery (%)

The Osaka refinery originally used oxidizing roasting to remove selenium - smelting matte and precious lead - ash blowing (oxidative refining) - silver and gold electrolysis processes were studied on flotation copper anode slime. Flotation can remove lead, and the yield of gold, silver and selenium entering the concentrate is 85% to 95%. But lead removal is not ideal. Further research on two grinding methods was carried out using a tower mill. The first type is a mud concentration of 20% to 30%, which is placed in an acid-resistant circulation tank, and is ejected from the split port at a speed of 4 to 6 m/s to cause mutual impact, and is ground to 3 μm or less after 10 to 15 hours; The grinding machine is equipped with 5 blades and filled with 20mm steel balls. The concentration of the slurry is 40% to 50%, and it can be ground to 3μm after 2~6h. Later, copper removal and grinding were combined into one process to increase the speed of copper removal. The process flow is shown in Figure 1. Due to the removal of copper and lead, it provides favorable conditions for the next smelting treatment. The float is selected from Denver-type flotation machine (type 910 of Section 910); pH=2, collector 208 black medicine 50g/t, pulp concentration 100g/L. The process of flotation of copper anode mud is simple, and the process of copper removal and grinding can be shortened. During flotation, gold, silver, selenium, tellurium, platinum and palladium enter the concentrate to obtain enrichment. The flotation technical indexes are shown in Table 2. The flotation concentrate is in the same furnace, and the oxidative roasting, smelting and silver separation are carried out continuously. There are three processes, and no flux and reducing agent are added during smelting, and soot and lead oxide by-products are also produced.

Fig.1 Flow chart of processing copper anode mud by flotation method in Osaka refinery

Table 2 Osaka refinery flotation technical indicators