Mankind has mined silver for thousands of years. Two early methods of mining silver were sluicing and hard-wall extraction. Sluicing involves assembling trenches in irrigation holes to filter out heavy metals from the mine. Unfortunately, sluicing is inefficient and ineffective method for obtaining silver. Hard-wall extraction is a basic silver mining method that is still used today, although with greatly improved machinery.
In hard-wall extraction, drills and heavy machinery are used to get at the ore. While deposits of pure silver are still found, they are rare. More often, silver is found with other elements such as lead, zinc and copper buried deep in the earth. Once discovered, an underground mine must be dug and constructed. Large volumes of the ore are drilled and blasted. The ore is transferred to underground rock crushers. Crushed ore is then hoisted up to the surface or driven by truck via a spiral tunnel or decline ramp.
On the surface, the ore is crushed even finer and then ground. A flotation process separates silver-bearing galena from waste rock particles called tailings. The flotation process was developed in the 19th century and is still used today, with many improvements over time. The process involves mixing the ground-up ore, water and chemicals, which are then agitated in the flotation cells. When air is blown through the mixture in the cell, the silver galena rises while the tailings sink to the bottom of the cell. The resulting silver-lead sulfide concentrate is then melted to combine the particles into lumps, removing the sulfur as sulfur dioxide. The silver mixture is further refined by various methods until pure silver is obtained.
http://www.australianminesatlas.gov.au/education/fact_sheets/silver.jsp
http://www.precious-metal.net/silver/silver-mining/#ixzz1eYkq5Isu
http://www.madehow.com/Volume-3/Silver.html
