Bioleaching Process for Copper Extraction from Waste in Alkaline and Acid Medium

Ivica Ristović,Emilija Širadović,Jaroslav Šuba,Iveta Štyriaková,Darina Štyriaková

doi:10.3390/min12010100

Ivica Ristović, Emilija Širadović + Show 3 more

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https://doi.org/10.3390/min12010100

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Abstract

Flotation wastes are becoming a valuable secondary raw material and source of many metals and semimetals worldwide with the possibilities of industrial recycling. The flotation tailings contain oxide and sulfide minerals that have not been sufficiently stabilized and form acidic mine waters, which in turn contaminate groundwater, rivers, and reservoi6sediments. An effective way to recycle these mine wastes is to recover the metals through leaching. While the focus is on acid bioleaching by iron- and sulfur-oxidizing bacteria, alkaline leaching, and the removal of iron-containing surface coatings on sulfide minerals contribute significantly to the overall environmental efficiency of leaching. For this study, static and percolate bioleaching of copper from flotation waste at the Bor copper mine in Serbia was investigated in alkaline and then acidic environments. The aim of the study was to verify the effect of alkaline pH and nutrient stimulation on the bioleaching process and element extraction. A sample was taken from a mine waste site, which was characterized by XRF analyses. The concentration of leached copper was increased when copper oxide minerals dissolved during alkaline bioleaching. The highest copper yield during alkaline bioleaching was achieved after 9 days and reached 67%. The addition of nutrients in acidic medium enhanced the degradation of sulfide minerals and increased Cu recovery to 74%, while Fe and Ag recoveries were not significantly affected. Combined bioleaching with alkaline media and iron- and sulfur-oxidizing bacteria in acidic media should be a good reference for ecological Cu recovery from copper oxide and sulfide wastes.

Highlights

The copper and precious metal deposits in the territory of the town of Bor in the Republic of Serbia were discovered at the beginning of the 20th century
The addition of nutrients in acidic medium enhanced the degradation of sulfide minerals and increased Cu recovery to 74%, while Fe and Ag recoveries were not significantly affected
The flotation waste consists of fine-grained particles and, in the presence of biogeochemical substances, represents a dangerous reactive potential for the extraction of heavy metal ions and the formation of acid mine drainage

Summary

Introduction

The copper and precious metal deposits in the territory of the town of Bor in the Republic of Serbia were discovered at the beginning of the 20th century. There have been two world wars, changes in ore processing technologies, and the Bor mine has been closed and reopened several times. The entire radius around the town of Bor was the focus of investors for the exploitation of copper and gold. Constant mismanagement led to the sale of part of the company (63%) to the Chinese partner Serbia Zijin Copper DOO Bor. The main activity of the company is mining and processing of copper ore, and the production of cathode copper, copper wire, gold and silver, sulfuric acid, copper sulfate, selenium, platinum, palladium, brass, bronze, and precious metal salts

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