Silver minerals in gold-silver ores are diverse and often appear in various states. Therefore, processing gold-silver ore commonly involves using two or more methods in a combined process. Overall, ore dressing methods for silver-gold ores mainly include flotation or cyanidation.
The choice between these two silver recovery methods depends largely on the composition of silver minerals. When silver minerals are primarily acanthite and native silver, both flotation and cyanidation can be employed. However, if the ore contains significant amounts of difficult-to-cyanide minerals such as ruby silver, light ruby silver, selenide, then only flotation can be used.
It is important to note that there is a difference in recovery rates between flotation and cyanidation, with cyanidation generally achieving higher recovery rates than flotation.
Common ore dressing processes for gold-silver ores include the following:
1.Flotation + Flotation Concentrate Cyanidation
The sulfide ore from gold-silver quartz veins is subjected to flotation to obtain a small amount of concentrate, which is then cyanided. Compared to the full mud cyanidation process, flotation concentrate cyanidation has advantages such as not requiring complete fine grinding of all ores, saving power consumption, smaller plant area, and reduced infrastructure investment.
2.Flotation + Concentrate Roasting + Roasted Sands Cyanidation
This process is often used to treat refractory gold-arsenic ores, gold-antimony ores, and ores with high sulfur content, such as gold-pyrite. Roasting aims to remove harmful elements like arsenic and antimony that are detrimental to the cyanidation process.
3.Flotation + Flotation Concentrate Pyrometallurgical Processing
This method is widely used for processing most gold-silver polymetallic sulfide ores. During flotation, gold and silver enter closely associated copper, lead, and other metal minerals, which are then sent to smelters for the recovery of gold and silver.
4.Flotation + Cyanidation of Flotation Tailing or Middlings + On-Site Roasting Cyanidation of Flotation Concentrate
This scheme is used to treat quartz-sulfide ores containing antimonial gold, magnetic pyrite, chalcopyrite, and other sulfide minerals. Sulfide minerals that can float are made into concentrate, exposing gold and silver in sulfides, followed by roasting and then cyanidation. Since the flotation tailings generally still contain high levels of gold and silver, cyanidation is performed again to recover them.
5.Direct Cyanidation of Original Ore + Flotation of Cyanide Tailing
When cyanidation alone cannot completely recover gold and silver coexisting with sulfides in the ore, the residue after cyanidation is subjected to flotation, which can improve the recovery rates of gold and silver.
