Mining in focus
Copper mining and processing : a trip down memory lane
It is almost impossible to imagine a world without copper , writes Dineo Phoshoko .
The World Copper Factbook 2017 , compiled by the International Copper Study Group ( ICSG ) in 2017 , defines copper as a “ malleable and ductile metallic element ”. Copper is also considered to be a good source for conducting heat and electricity .
The metal has various uses , some of which are unique to copper . Transport , appliances , electronics , and power generation are among the end uses of the final product .
In an article for the Copper Development Association , Vin Calcutt highlights the fact that copper minerals and ores are located in igneous and sedimentary rocks . As such , copper can be mined using both underground and opencast mining methods . In the article , titled “ Introduction to Copper : Mining & Extraction ”, Calcutt explains that copper mined underground usually has higher quality compared to copper mined using opencast mining methods .
Conventional copper processing
The copper mining industry has seen many innovations in the extraction process throughout the years . Before today ’ s technology , copper was extracted using conventional methods of leach , solvent extraction and electrowinning ( L / SX / EW ).
In a paper written for the Journal of the South African Institute of Mining and Metallurgy , GA Kordosky outlines the three methods used in the extraction of copper before the emergence of technological innovations .
The paper titled “ Copper recovery using leach / solvent extraction / electrowinning technology : Forty years of innovation , 2.2 million tonnes of copper annually ”,
Kordosky mentions that in 1968 , there were only two practices for copper leaching . The first process was the vat leaching of high-grade copper oxide ore . The process was followed by electrowinning of copper from the leach solution — which produces low-quality copper cathode at a high cost . A decrease in the tonnage of high-grade oxide ores in 1968 resulted in a decline in the vat-leaching process .
The second copper leaching process is the heap and dump leaching method . In his paper , Kordosky explains that the “ heap and dump leaching of low-grade oxide and / or sulphide ore was followed by precipitation of low-quality copper from the leach solution on scrap iron ”. This process was practiced on oxide ore that was either too low-grade for vat leaching , or low-grade sulphide ore that needed to be mined to expose the underlying high-grade sulphide ore . In those days , recovering copper from leaching low-grade copper ores was very beneficial because understanding the leaching process required minimal effort . Kordosky explained that both these processes — vat and copper leaching — used diluted sulphuric acid .
Improvement in copper mining processes
In that same year , Rancher ’ s Bluebird copper solvent extraction plant was built for copper operation in Arizona , US . With the plant came technological innovation that raised the bar on improving copper extraction methods . The plant illustrated that L / SX / EW technology had the ability to produce large quantities of good quality cathode copper consistently on a daily basis .
[ 38 ] MINING MIRROR SEPTEMBER 2018