[VIDEO] The History and Process of Silver Mining
While the search for silver dates back as early as the 4th millennium B.C. it wasn’t until the mid-15th century when the precious metal began to be extracted in massive quantities. Today, more than 671 million troy ounces of silver are mined around the world annually.
The video below reveals the silver mining process as shown at the Silver Valley mining complex in northern Idaho.
The process of mining for silver
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.
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.
Global iron ore production to recover by 5.1% in 2021
Global iron ore production fell by 3% to 2.2bnt in 2020. Global production is expected to grow at a compound annual growth rate (CAGR) of 3.7% to 2,663.4Mt between 2021 to 2025. The key contributors to this grow will be Brazil (6.2%), South Africa (4.1%), Australia (3.2%) and India (2.9%). Key upcoming projects expected to commence operations include South Flank in Australia (2021), Zulti in South Africa (H2 2021), Serrote Da Laje in Brazil (H2 2021) and Gudai-Darri (2022), according to GlobalData, a leading data and analytics company.
Vinneth Bajaj, Associate Project Manager at GlobalData, comments: “Declines from Brazil and India were major contributors to the reduced output in 2020. Combined production from these two countries fell from a collective 638.2Mt in 2019 to an estimated 591.1Mt in 2020. The reduced output from the iron ore giant, Vale, was the key factor behind Brazil’s reduced output, while delays in the auctioning of mines in Odisha affected India’s output in 2020.
“Miners in Australia were relatively unaffected by COVID-19 due to effective measures adopted by the Australian Government, while a speedy recovery in China led to a significant 10.4% increase in the country’s iron ore output.”
Looking ahead, the global iron ore production is expected to increase by 111.3Mt to 2,302.5Mt in 2021. Rio Tinto is expected to produce up to 340Mt of iron ore, while BHP has released production guidance of 245–255Mt, supported by the start of the Samarco project in December, which is expected to produce between 1–2Mt.The company has retained its guidance for Australian mines at 276–286Mt on a 100% basis, due to scheduled maintenance work at its ore handling plant and tie-in activity at the Area C mine and South-Flank mine.
Bajaj added: “The remaining companies are expected to produce more than 600Mt of iron ore, including FMG, whose production is expected to range between 175–180Mt supported by its Eliwana mine that commenced operations in late December 2020, and Anglo American, which is expecting to produce between 64–67Mt. Vale is expected to resume 40Mt of its production capacity, taking its overall production capacity to 350Mt in 2021, with production guidance of 315-335Mt.”