Performing a factory gold containing 49.85g / L, palladium 4.74g / L, Pt 0.68g / L of a gold waste electrolysis experiments were conducted using ferrous sulfate, sulfur dioxide, and oxalic acid reduction of gold, of gold is precipitated and semen The distribution ratios of platinum and palladium are shown in the following table.
Table Gold Platinum Palladium Recovery Rate (%)
reducing agent | gold | palladium | platinum |
Ferrous sulfate | 99.13 | 95.99 | 100.00 |
Sulfur dioxide | 99.93 | 51.39 | 95.60 |
oxalic acid | 96.01 | 97.05 | 92.53 |
It can be seen from the above table that the reduction rate of ferrous reduction gold is high, the loss of platinum and palladium is less, and the oxalic acid is the lowest; the reduction rate of sulfur dioxide reduction gold is the highest, but the loss of palladium is too large, which may be the formation of insoluble palladium network. The reason of salt. After the gold reduction solution, a small amount of gold is still contained, and then the zinc block is replaced. The recovery rate of the precious metal is (%): Au99.77, Pd98.93, and Pt is about 100. When the acidity of the solution is increased to 2 mol, the zinc reduction effect is better. For example, the filtrate of oxalic acid reduced gold is replaced with zinc instead of formic acid. The solution is adjusted to pH 6 and then formic acid is added. The recovery of precious metals is (%): Au99.70, Pd99.97, Pt96.09.
According to the experience of a company using zinc replacement method for more than ten years of treatment of various precious metal chlorinating liquids and refining process waste liquids, zinc replacement method is a simple and easy process, complete replacement, easy operation and no need for special equipment. A reliable method of doing things. In the residual liquid after being stirred by the air and finally replaced by zinc powder, gold, platinum and palladium are below 0.0005 g ∕L, which meets the standard of production waste. The substitution recovery of gold, platinum and palladium is between 99 and 99.9%, and the effect is satisfactory. In order to get better results, you can also take the following measures:
(1) The acidity of the replacement liquid can be appropriately increased and stirred by air to prevent the zinc powder in the precious metal concentrate from being too high. If the zinc powder is too high, it can be heated to 80-90 ° C in a 3 mol / L hydrochloric acid solution to stir and remove zinc.
(2) the solution containing copper and other base metals is too high, instead replaced copper. The obtained precious metal concentrate was replaced with zinc or copper, and copper was removed by leaching with 60 g of a high-iron solution of sulphuric acid.
(3) A solution containing a medium of nitric acid and nitrous acid. The zinc replacement method cannot completely recover the precious metal and should be avoided.
The former Soviet Union used electrolysis to treat gold electrolysis waste. In the waste method, in the electrolytic solution of gold, the electrolytic waste liquid is injected into the cathode diaphragm, and the anode in the anode region is dissolved, and the gold in the waste electrolyte is precipitated on the cathode. The precipitated anode gold is used for casting anodes.
A mine used hydrazine hydrate to extract gold from gold electrolysis waste liquid, and then replaced and reduced to supply gold anode.
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