Volume 4, Issue 2, June 2019, Page: 44-50
Effluents Treatment Generated by Biolixiviation in the Extraction of Precious Metals through Selective Recovery of Iron, Copper and Zinc
Zambrano Johanna, Department of Chemical Engineering and Environmental Technology, University of Valladolid, Valladolid, Spain
Zambrano Johnny, Department of Petroleum, Escuela Politécnica Nacional, Quito, Ecuador
Received: Jul. 16, 2019;       Accepted: Aug. 12, 2019;       Published: Sep. 2, 2019
DOI: 10.11648/j.ijmpem.20190402.12      View  22      Downloads  13
Abstract
Bioleaching comprises the use of microorganisms for metal-extraction processes from sulphide ores. During these complex processes, sulphides are oxidized to sulphates with the generation of heat. As a result, gold, silver, and other precious metals are liberated from the sulphide matrix, improving their recovery after further processing. A drawback of bioleaching processes is the generation of significant amounts of acid solutions with high heavy metal concentrations. If untreated, these acid solutions may alter the physical and chemical characteristics of water and its surroundings, with high impact to aquatic ecosystems. High heavy metal concentrations in solution may also result in pollution to living organisms. A feasible method to treat bioleaching-generated solutions is selective precipitation. This investigation presents the conditions for a successful individual recovery of the main base metals contained in a bioleaching solution with high copper, zinc, and iron concentrations by pH-based selective precipitation. Tests were made with standard solutions of known concentrations of copper, iron, lead and zinc and by titration the concentrations were checked; which allowed to validate the volumetric titration method. The selective precipitation of heavy metals was carried out in three phases using real acid main drainage and bioleaching solutions generated at the laboratory. The first phase in a pH range of 2 to 4 to recover iron; the second phase in a pH range of 4 to 6 to recover copper; and the third phase in a pH range of 6 to 10 to recover zinc. The selective precipitation allowed the heavy metals to be completely removed from the solution or to achieve concentrations below the maximum allowable limit to be discharged to a body of water or public sewer. Results portray that the variation of pH is an effective method, easy to use and not expensive, feasible to be used in the purification of waters that have been polluted with heavy metals.
Keywords
Bioleaching, Precious Metals, Selective Recovery, Effluent Treatment
To cite this article
Zambrano Johanna, Zambrano Johnny, Effluents Treatment Generated by Biolixiviation in the Extraction of Precious Metals through Selective Recovery of Iron, Copper and Zinc, International Journal of Mineral Processing and Extractive Metallurgy. Vol. 4, No. 2, 2019, pp. 44-50. doi: 10.11648/j.ijmpem.20190402.12
Copyright
Copyright © 2019 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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