Silver Mining

What is Silver

Silver (Ag) has a bright, metallic luster, and when untarnished, has a white color. It is rarely found in its native form. Silver can be found combined with a number of different elements such as sulfur, arsenic, antimony or chlorine to form a variety of minerals and ores, such as argentite, chlorargyrite, and galena. It is also found in very small amounts in gold, lead, zinc and copper ores. Silver is malleable which means it can be hammered into thin sheets. It is also ductile, meaning it can be drawn into wire.

Silver Mining

Silver is found in lead, zinc, gold and copper ore deposits. The most important ore mineral of silver is argentite (Ag2S, silver sulfide). Silver is commonly extracted from ore by smelting or chemical leaching.

Silver Uses

Silver has been used for thousands of years for jewelry and decorative items of all types. Likewise, it has been used for silverware. Of all the metals, untarnished silver is the best reflector of light. As a result, it was used in ancient times to make mirrors. Sterling silver is silver alloyed with another metal, usually copper. For such an alloy to be called “Sterling” it has to have 92.5% silver content. Silver bromide and silver nitrate are used in photography. It is used in various photographic materials and processes. It is also used in electrical products because it conducts electricity more efficiently than copper. It has been used by dentists in amalgam fillings.

Silver Mining Process

The process of mining for silver is broken down into three steps: removing ore from the earth, breaking it down and then flushing the silver from ore. The first step involves drilling holes in the silver-rich areas geologists have previously pinpointed and then inserting dynamite sticks. After the blast, miners haul the chunks of rock called ore to the surface. The geologists then test the ore piles and blend them as required to achieve a consistent amount of silver content per kilogram of ore.

Crushing ore

The ore first goes into the primary crusher, breaking up the big chunks into smaller pieces which then go down into a secondary crusher that breaks it down into smaller pieces. Those pieces then go into a vibrating cone crusher which pulverizes it into tiny pieces. A conveyor then transports the crushed ore to a ball mill, which grinds the ore into powder. A water circulation system flushes the silver rich powder out of the cylinder and into larger tanks. Worker then pour acid in to separate and dissolve the various metals the powder contains.

The dissolved silver is then pumped through filter presses and filter plates are treated with a zinc-based chemical that attracts silver molecules. The plates trap particles containing silver, forming a layer of black powdered called silver precipitate, which is composed of 50 percent of silver and 50 percent of waste.

Recovering the silver

To separate the silver from the waste, miners dry the precipitate in a gas furnace for a few hours while continuously testing ore samples to determine the grade. The samples are then heated to 1093 Celsius to burn off the impurities, leaving the silver and other metals such as lead, zinc and copper remaining. Lab technicians then treat the samples with a chemical that prevents the remaining silver from burning off. The sample is then inserted back into the furnace.

After about an hour, once all the other metals have burned off, the only thing left is silver.