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Xinhai mineral processing equipment mainly include: grinding equipment, flotation equipment, dewatering equipment, magnetic separation equipment, and so on. Some of the equipment is Xinhai independent research and development, and has been awarded national patent. View details
Gold CIL (Carbon in Leach) Process is an efficient design of extracting and recovering gold from its ore. By cyaniding and carbon leaching crushed gold ore slurry simultaneously, CIL process lower the gold mining operation cost and increase gold recovery rate to a degree of 99%. View details
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Talking about extracting gold, zinc replacement technology is also a common gold extraction method besides CIP and CIL. How much do you know about zinc powder replacement technology?
Zinc powder replacement is used to deal with the pregnant solution from gold cyanidation. The principle is replacing gold or silver with zinc powder from leaching extract. It can also use zinc wire instead of zinc powder in industry, which has similar operations with zinc powder replacement technology.
Zinc powder replacement includes four operations such as: washing (solid-liquid separation), purification, deoxidation, and replacement.
1. Washing: Separate the leaching solution with solid after cyanidation.
2. Purification: Weed out the suspended solids in leaching solution and keep the pregnant solution clear until into replacement operation.
Remove dissolved oxygen from the pregnant solution (leaching solution).
3. Replacement: Replace precious metal with zinc powder from pregnant solution (leaching solution), and receive gold or silver clay.
The main factors that can influence zinc powder replacement technology includes: concentration of cyanidation and alkali, concentration of oxide, the role of lead salts, temperature and impurities in solution, the purification of pregnant solution(leaching solution).
1. Concentration of cyanidation and alkali
When cyanidation is in low concentration, zinc will react into zinc hydroxide and zinc cyanide on the surface, which prevents the replacement of gold. If the concentration of cyanidation and alkali is too high, the speed of zinc dissolution is increased which is good for the replacement of gold but also increase the consumption of zinc and the production cost. So the concentration of cyanidation and alkali must be controlled during production.
2. Concentration of oxide
The dissolved oxide in the solution is harmful to zinc replacement. It will influence the effect of zinc replacement. So deoxidation must be done before replacement and keep the leakproofness of deoxidation and replacement system. The reaction could not carry on if this part of system leak air.
3. Effect of lead salt
In the displacement process, the main function of lead is to form “zinc-lead electric couple” with zinc, then dissolve gold. The common lead salt used in the production includes lead nitrate and lead acetate. The lead can accelerate the displacement of gold ore, but the excessive lead can cover the surface of zinc and slow down the displacement rate. If too much lead enters the gold slime, the grade of gold will be decreased. Therefore, the amount of lead salt used in the production should be appropriate.
4. Temperature and impurity in solution
The increasing temperature will accelerate the rate of displacement reaction. If the temperature is below 15 ℃, the displacement ratio will be affected. The impurities in the solution mainly include copper, mercury, nickel and soluble sulfide, etc. The copper can make the zinc powder form a layer on the surface, which decreases the contact area; the mercury complex is easy to react with zinc, then form an alloy, which makes zinc brittle; the soluble sulfide will react with zinc and lead, and produce zinc sulfide and lead sulfide on the surface of zinc and lead.
5. Cleanliness of pregnant solution (leaching liquid)
The cleanliness of pregnant solution (leaching liquid) is one of the important conditions that affect the zinc powder displacement. The suspended solids and oils that exceed the requirements are not allowed in the pregnant solution (leaching liquid). The oils that mix in the pregnant solution will form an oil film covering the surface of zinc, then affect the displacement effect. The slime will block the filter cloth of the displacement equipment and affect the displacement operation, even affect the quality of gold slime.
In the production, the gold can be recovered by zinc powder (silk) replacement and precipitation, that is cyano-zinc displacement process (CCD process and CCF process). Besides, the zinc powder displacement can also be used to process the pregnant solution (leaching liquid) after pool leaching or heap leaching. Generally speaking, the gold ore with high silver can be treated by zinc powder displacement method, which is beneficial to the recovery of silver. In addition, zinc powder displacement process can also be used to treat the gold concentrate that needs to be upgraded.
It is necessary to consider more problems than those ideal conditions in the laboratory during the actual production. Xinhai Mining suggests that each mine owner should decide whether adopt zinc powder displacement process or not under the mineral processing test results, plant size, plant conditions, investment cost, then the balance between the technical index and economic index can be achieved.
In the future, Xinhai Mining will continue to implement the development strategy of "manufacturing servicizing""development innovation" and "market internationalization", provide the customized " mineral processing EPC+M+O service" for global mines, and help to build a community of global mining development. Dream building is underway…… ... [more]
In general, the gold extraction process is mainly flotation and gold cyanidation, while the gold cyanidation extraction process can also be divided into carbon in pulp process, carbon in leaching process, heap leaching process and so on. This post mainly introduces the comparison between the flotation gold extraction process and gold cyanidation process. ... [more]
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© 2017 Shandong Xinhai Mining Technology & Equipment Inc.