Lead-zinc ore is separated by what method?

Lead-zinc ore can be separated using cyanide and non-cyanide methods.

①Cyanide method: The cyanide method uses less dosage, the process is relatively stable, it is easy to operate and control, and the process indicators are better, so there are still many factories using it. However, because cyanide is toxic and easily dissolves gold and silver, many mines use the non-cyanide method, or use less cyanide in combination with zinc sulfate. For example, a processing plant uses sodium cyanide in combination with zinc sulfate to reduce the amount of cyanide. To 20–30g/t, some even drop to 3–5g/t.

CASE:

A lead-zinc deposit is a metasomatic deposit in dry carbonate rocks. The lead mineral in the ore is galena, with a small amount of lead alum. The zinc minerals are sphalerite and a small amount of smithsonite. Iron sulfide is pyrite, gangue is calcite, quartz, feldspar, etc.

Selection indicator	Raw ore grade (%)	Concentrate grade (%)	Capacity（%）
Pb	2.35	71	90
Zn	2.96	53	92
S	11.14	36	74

Lead and zinc are separated using the cyanide method. The buoyancy of part of sphalerite in the ore is similar to that of galena, while the floatability of hard-to-float sphalerite is similar to that of pyrite. Therefore, when floating lead, under the principle of floating net lead, part of the easy-floating sphalerite is floated, and the tailings with floating lead are then mixed with zinc and sulfur. This is the iso-floating process of “lead-zinc iso-floating” and “zinc-sulfur iso-floating”.

②Non-cyanide method:
A lead-zinc sulfide ore adopts a high-quality flotation process, and ZnSO4+Na2CO3 (14:1) was used to suppress sphalerite when floating lead.
Compared with the cyanidation method, the grade of lead concentrate increased from 39.12% to 41.80%, the recovery rate increased from 74.59% to 75.60%, the grade of zinc concentrate increased from 43.59% to 48.43%, and the recovery rate increased from 88.5%
to 90.30%. The plant has also used Na2SO3+ZnSO4 and ZnSO4 alone to suppress sphalerite, and can also get better indicators.

In foreign countries, SO gas is often used to suppress zinc. For example, in Japan’s Toyoba lead-zinc-sulfur mine, when the lead-sulfur is mixed, it is ground to 45%-0.075mm, and SO gas is used to suppress zinc, and the tailings are reground to float zinc. The lead-sulfur mixed concentrate is reground for lead-sulfur separation, and cyanide is used to suppress sulfur and float the lead.

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