Zinc powder replacement device is a system that uses zinc powder to extract gold from precious liquid.The device is mainly aimed at gold ore containing more silver. After purification and deoxidation of the precious liquid, a zinc powder replacement device is added to obtain gold mud.
The basic principle of zinc replacement precipitation gold is that the zinc in the precious liquid will dissolve in the solution and the gold will precipitate out.When zinc is replaced, there must be enough cyanide and alkali in the solution, otherwise the dissolved oxygen in the gold-containing solution will redissolve the precipitated gold powder and oxidize zinc to Zn(OH)2 precipitation.Also Na2Zn(CN)4 in solution will decompose into insoluble zinc cyanide precipitate.
These zinc hydroxide and zinc cyanide are white precipitates, which will form a film on the surface of metal zinc, thus hindering the replacement of gold by zinc from the noble liquid. Therefore, the use of a deoxygenation tower to remove dissolved oxygen in the precious liquid before precipitating gold will be beneficial to the substitutional precipitation of gold. Add a small amount of lead acetate and lead nitrate to the precipitation tank to help dissolve the zinc and better replace the precipitated gold. Impurities such as soluble sulfide, mercury, and copper contained in the precious liquid hinder the substitution and precipitation of gold.
The main operations of the CCD method process are: cyanidation leaching, solid-liquid separation and washing, clarification and purification of precious liquid, deoxidation, and zinc replacement of precious liquid.
1. Washing: separate the cyanidated precious liquid (leaching liquid) from the solid.
2. Purification: Remove the suspended solids in the precious liquid (leaching liquid), so that the gold-containing precious liquid entering the replacement operation reaches a clear and transparent state.
3. Deoxidation: remove the dissolved oxygen in the precious liquid (leaching liquid).
4. Replacement: Replace the precious metal in the precious liquid (leaching solution) with zinc powder to form gold (silver) mud.
The zinc replacement method mainly includes two methods: zinc wire replacement and zinc powder replacement.
Zinc powder has a large specific surface area, which is conducive to full and rapid replacement of precipitated gold. In recent years, the zinc wire replacement method has been replaced by the more advanced zinc powder replacement method. Compared with the two, zinc powder replacement has the following advantages.
1. The price of zinc powder is relatively low and the dosage is small. Under the same conditions, the dosage of zinc powder is only 1/10~1/4 of that of zinc wire.
2. The gold-silver replacement precipitation is more complete, and a higher recovery rate can be obtained.
3. The zinc content in the gold mud is small, which simplifies the next step of gold mud treatment.
4. The entire operation process can be mechanized and automated.
