Study for the Production of Gypsum in the Acid Effluent Treatment Plant of Paipote Smelter

Copper 2010 Conference Proceedings vol 1, p 465, Downstream Fabrication, Application and New Products, Sustainable Development/Health, Safety and Environmental Control. 2010.


The National Mining Company (ENAMI), on its project for increasing the treatment capacity of liquid effluents from its acid plant of the Paipote Smelter, developed a research Project with Univer- sidad de Concepción, to determine the feasibility of producing gypsum as an intermediate product during the liquid effluent neutralization process. A pilot plant with two agitated reactors in series, with 100 litres of capacity each were built, and allowed to simulate and evaluate a continuous neu- tralization process. The effluents contain approximately 75 g/l sulphuric acid and impurities coming from the gas scrubbing stage, before they enter the acid plant. Results indicate that it is, in fact, fea- sible to obtain clean gypsum when neutralizing the liquid effluents with lime when the neutraliza- tion pH is equal or less than 1. Filtering and washing of the solid residue were evaluated, followed by a characterization of the final product through chemical analysis and TCLP test, to determine its hazardousness. Both analyses showed the feasibility of producing clean gypsum which, besides the possibility of being commercialized, accounts for most of the volume of the residue generated by the liquid effluent neutralization plant. An aspect that must be considered when implementing this alternative is to characterize the presence of solids in suspension that could be contained on the acid effluent.

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