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Silver Mining Extraction Methods

Extracting silver from ore containing the metal starts with open pit or underground mines. Miners extract the silver-bearing ore, crush and grind it and separate it into parts containing different metals by flotation. Silver exists in mineral form as a sulfide, along with high concentrations of the sulfides of other metals such as copper, lead and zinc. Depending on which metal is carrying the silver sulfides, miners apply corresponding metallurgical processes to obtain the other metals and refined silver.

Flotation
- After grinding the ore to powder, miners use flotation to separate the metal-containing particles from the sand and mud. They bubble air through water containing the ore, and particles containing metal sulfides sink to the bottom while mud and sand are washed away. The remaining sludge is called the concentrate and may contain over 50 percent sulfides, while the initial ore was mostly sand and mud and might have contained only three or four percent sulfides.
Lead Concentrates
- Miners first roast lead concentrates containing silver to remove gaseous impurities. They then smelt it to extract the metals and make lead bullion containing silver and other metals. Zinc, added to the molten lead, reacts with the silver and any gold to form compounds that float to the top. After skimming off this material made up of silver, lead and gold compounds of zinc, metallurgists extract the zinc and lead by oxidizing them at about 1450 degrees Fahrenheit. Electrolysis separates the remaining silver from any gold to produce high purity metallic silver
Zinc Concentrates
- Zinc concentrates typically also contain lead sulfides. Miners initially roast them as they do lead concentrates but then treat them with sulfuric acid to dissolve the zinc sulfide and remove it. The remaining residue of lead, silver and other metals still contains some zinc sulfide. Miners melt the mixture and blow powdered coke across it to reduce the lead and zinc to their metallic states. The zinc then vaporizes leaving the molten lead, silver and other metals. Miners refine this material the same way as the lead bullion obtained under Section 2.
Copper Concentrates
- Miners refine copper concentrates by smelting the copper and producing metallic copper bars that also contain the silver present in the ore. They then extract the copper by electrolysis, leaving the silver in the remaining residue. Smelting the residue extracts a mixture of silver and any other noble metals present in the ore. This material, called dorZ metal, usually contains mostly silver with up to five percent gold and less than one percent platinum. Electrolysis of this metallic mixture produces high purity metallic silver.

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