Yunnan Smelter

Yunnan smelter copper anode slime treatment began in 1969, using traditional domestic fire process, years of industrial practice shows, lead, selenium and environmental pollution, harsh operating conditions, high processing costs, precious metals recovery rate is low, only 65 %~82%. To this end, in 1975, it cooperated with the Kunming Institute of Metallurgy to study the joint process of smelting and smelting. In 1976, it conducted industrial tests and passed the appraisal meeting in June 1977. And through 16 years of production practice and continue to improve, improve, 1991, gold and silver recovery rate of 99.51% and 99.64%, respectively. The average composition of anode mud in 1991: Au 0.355%, Ag 15.48%, Cu 11.3% (including water soluble Cu 4.97%), Se 2.62%, Te 1.28% ~ 2%, Pb 10% ~ 15%, Bi0 .3% to 1%, SiO ₂ 3% to 5%, Pt 5.3 g/t, Pd 19 g/t (and Sn). The current process is to dissolve and separate copper, selenium, tellurium , arsenic, etc. in the anode mud by wet method; then, the lead, bismuth , antimony and gangue components in the anode mud are separated by flotation, so that the silver is enriched by 15%. 45% to 50%. Then, it is smelted into a small converter, oxidized and refined into gold and silver alloy plates, and then obtained by using an electrolytic alloy plate to obtain pure silver. The anode slime of electrolytic silver is extracted by liquid chlorination method for gold, platinum and palladium .

Specific procedures:

First, the anode mud pre-de-steel, de-selenium, enhanced scrubbing and flotation, the process is shown in Figure 1. After the anode mud is treated with dilute sulfuric acid, the removal rate of copper is over 90%; the anode mud after decoppering is denitrified with MnO ₂ , NaCl, H ₂ SO ₄ in the reactor, and the end point is adjusted with a small amount of NaClO ₂ . callback performed with scrap iron, greater than 90% removal of selenium, tellurium removal rate of more than 50%; selenium tellurium slurry removal after the filtration plate and frame filter press to give a gold less than 0.001g / L selenium containing solution, the iron solution was The crumb replacement obtains the crude selenium slag for extracting selenium and bismuth, and the filter cake is subjected to flotation enhanced scrubbing and then flotation. It is butyl xanthate flotation reagents, drugs and black-butyl ammonium phosphate, sodium hexametaphosphate, as in pine oil foaming agent, by a roughing, a selection, five scavenger, and tail obtained pulp slurry, Filtered separately by plate and frame filter press. Concentrate contains 45% to 50% of silver, 1.2% of gold, 5% of lead, 25% to 35% of water; silver with tailings <0.6%, containing <200g/t, lead 30%, é“‹0.74 %, copper 0.039%, silica 5.33%, can be treated separately.

Figure 1 Process of decoppering and selenium flotation

Second, the silver furnace melting, silver electrolytic silver, the process shown in Figure 2. Flotation concentrate is properly blended with sodium bicarbonate 14% to 22%, iron filings 2% to 8%, carbon powder 1% to 4%, quartz sand 2% to 10%, fluorite 2% to 5%, rotating Melting in a silver furnace. The smelting of the silver furnace is divided into two stages. The first stage melts to obtain a coarse alloy containing more than 68% of silver, and the second stage of the slag is discharged to oxidize and refine the oxidative refining, followed by oxygen to oxidize the alloy. When the alloy contains silver at 95% When the above oxidation is stopped, the gold and silver of the alloy are greater than or equal to 98%, and the alloy melt temperature is adjusted and cast into a gold or silver alloy plate, that is, a silver anode plate. Adopt the common silver electrolysis process in the same industry in China. Anode plate size: length 260mm, width 190mm, thickness 15mm, each piece about 7.5 ~ 8.1kg, each bar anode hanging 3 anode plates, double cloth bag. The cathode size is 330 mm long and 660 mm wide, with 5 rows of cathodes per cell and 4 rows of bars. A total of 2 to 12 slots, the total current in series is 300 ~ 400A. Electrolyte composition: Ag98 ~ 110g / L, acid 3 ~ 6g / L, stable production of No. 1 silver.

Figure 2 Smelting, refining, electrolysis process

3. Activated carbon adsorbs platinum and palladium in silver electrolyte. The silver electrolyte contains platinum 0.05g/L and palladium 0.12～0.35g/L, accounting for 45.36%～57.9% of the total content of platinum and palladium in the anode plate. After the activated carbon of palladium is reduced by combustion, it is chlorinated, and ammonium chloroplatinate is neutralized with ammonium to obtain platinum-palladium separation. As shown in FIG. 3, the gold-containing chlorinated slag is combined with gold in a liquid chlorination recovery process.

Figure 3 Platinum and palladium separation process

4. The anode slime after silver electrolysis is leached with hydrochloric acid, sodium chloride and chlorine chloride. The chlorinated slag is replaced by iron powder to recover the silver powder and returned to the silver furnace. The chlorinated liquid neutralizes the oxalic acid to reduce the precipitate and obtains the gold powder. After the gold powder ingot is obtained, the gold ingot is obtained, and the gold chlorination method is shown in Fig. 4.

Figure 4 Chlorine liquid chlorination process gold extraction process

V. Recovery of SeO ₂ : The copper anode slime was treated by the combined process of metallurgy and smelting. In 1991, the gold recovery rate was 99.51%, and the silver recovery rate was 99.64%. Selenium recovery has been low due to process and equipment, and was only 40% in 1991. A method of improving the sulphation roasting is then found to link the improved sulphation roasting to the existing gold and silver flotation processes. The content of selenium before selenization was 3.44%. After selenization by sulphation, the content of selenium was 0.1%, and the removal rate of selenium was 91.95%.

The conditions of sulphation roasting are: temperature ≤400 ° C, time 3 to 4 h, material to acid ratio 1:1.32, roasting material after transformation and enhanced scrubbing and then into flotation beneficiation , the ore tailings containing gold and silver are consistent with the current production indicators. The concentrate yield is 33%, the tailings yield is 66%, and the enrichment ratio is greater than 4. After this adjustment, the new process of copper electrolysis anode mud smelting and smelting has maintained its original superiority. The total direct yield of selenium can be increased by more than 50%, and the selenium content of crude selenium produced can reach more than 85%. In order to provide high-quality raw materials for the purification of step selenium, the original wet de-selenization and chlorine-containing waste gas can be eliminated to the environment. The pollution and harm, but also eliminate the corrosion of chlorine ions on the equipment, creating conditions for the enrichment of the slag in the silver slag, which is conducive to the recovery of hydrazine. Due to the improved grade of silver concentrate, the furnace time is shortened, the energy consumption is reduced, and the single furnace treatment capacity is improved. The production process of SeO ₂ is shown in Figure 5.

Figure 5 Selenium dioxide production process

6. Flotation tailings composition: Au0.028%, Ag0.68%, Bi0.74%, Cu0.039%, Pb30.5%, Sn8.85%, Se trace, Te trace, SiO ₂ 5.33%. If this tailings is returned to the copper smelting system, it will inevitably cause dispersion and loss, so it should be recycled separately.

7. Silver furnace dust composition: Au0.023%, Ag2.01%, Sb3.82%, Pb20.93%, As0.82%. If the tailings return to the copper roughing system, it will inevitably cause the dispersion of valuable metals. Loss, so recycling should be handled separately.