Reduction of High-Chromium-Containing Wastewater in the Leaching of Pyritic Waste Rocks from Coal Mines

Rodrigo de Almeida Silva (), Marina Paula Secco, Jean Carlo Salomé dos Santos Menezes, Ivo André Homrich Schneider and Richard Thomas Lermen ()
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Rodrigo de Almeida Silva: Postgraduation Program of Civil Engineering, School of Engineering and Applied Sciences, ATITUS Educação, Passo Fundo 99070-220, RS, Brazil
Marina Paula Secco: Postgraduate Program in Civil Engineering (PPGEC), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre 90035-190, RS, Brazil
Jean Carlo Salomé dos Santos Menezes: Postgraduate Program in Civil and Environmental Engineering (PPGEng), University of Passo Fundo, Passo Fundo 99052-900, RS, Brazil
Ivo André Homrich Schneider: Postgraduate Program in Mining, Metallurgical and Materials Engineering (PPGE3M), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre 90130-120, RS, Brazil
Richard Thomas Lermen: Postgraduation Program of Civil Engineering, School of Engineering and Applied Sciences, ATITUS Educação, Passo Fundo 99070-220, RS, Brazil

Sustainability, 2022, vol. 14, issue 19, 1-15

Abstract: Coal is an abundant resource which can be used to produce low-cost energy; however, its usage causes great environmental damage. Before mineral coal can be used, it must be processed to remove coal tailings. These tailings contain pyrite and accumulate in large dumps, presenting significant environmental liabilities, such as acid mine drainage. Another industry that generates environmental liabilities is the chrome-plating industry, mainly because it produces hexavalent chromium (Cr 6+ ) waste. The main aim of this work was to evaluate Cr 6+ as a reduction agent in trivalent chromium (Cr 3+ ) conversion in the leaching of coal-mine waste containing pyrite. Cr 3+ is about 100 times less toxic than Cr 6+ and can be easily removed from industrial effluents by alkaline precipitation. There are several sources of effluents containing Cr 6+ —a compound which is known worldwide to be toxic, carcinogenic, and mutagenic. A leaching and treatment device was developed and tested for waste treatment. The results indicated that the developed treatment system reduced 100% of Cr 6+ to Cr 3+ through pyrite leaching in a Cr 6+ wastewater sample from the electroplating industry. In addition, the chromium sludge resulting from the treatment process, after calcination, was tested in a ceramic glaze as a pigment and, when compared with an industrial pigment, showed similar mineralogical characteristics.

Keywords: chromium reduction; pyrite oxidation; chromium pigment (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
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