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Type: Artigo de periódico
Title: Control of geochemical mobility of arsenic by liming in materials subjected to acid mine drainage
Author: de Andrade, RP
Figueiredo, BR
de Mello, JWV
Santos, JCZ
Zandonadi, LU
Abstract: Background. Acid mine drainage (AMD) results from the exposure of sulfide materials to atmospheric water and oxygen. In addition to AMD, oxidation of arsenopyrite and other As-bearing sulfides can release arsenic (As) into the environment. In view of the risk to living organisms due to contamination of ground and surface water sources with As, this work was carried out to evaluate the effectiveness of lime (CaCO3) in controlling the dispersion of this metalloid in the environment. Methods. Partially oxidized samples of sulfide bearing materials from gold mines in Brazil were used to evaluate the arsenic mobilization by leaching tests. Columns containing ground samples, with and without liming treatments, were leached with distilled water every two weeks over a 156-day period. Results and Discussion. The acid-base accounting (ABA) static tests classified the samples as potential acid forming materials. In the treatments without liming, As, Fe and S concentrations in the leachates were higher than after treatment with carbonate. Nevertheless, the effectiveness of liming and As mobilization were lower in the sample containing goethite. A high correlation between Fe and As concentrations in the leachates (r=0.749) suggests that iron (hydr)oxides retained arsenic in the solid phase. Oxidation rates of As bearing sulfides were increased at low pH (2.0-3.9), probably due to the enhanced activity of bacteria (Acidithiobacillus) and decreased rate of Fe precipitation, thus reinforcing generation of acid water, and consequently releasing As. Conclusions and Perspectives. Our results corroborate the use of lime to control the dispersion of As in AMD-affected environments. However, the effectiveness of the liming treatment seems to be dependent on the presence of iron (hydr)oxides in the sample. These findings can be useful to remediate areas affected by acid mine drainage and arsenic mobilization in partially oxidized sulfide materials.
Subject: acid mine drainage
geochemical mobility
iron oxides
Country: Alemanha
Editor: Ecomed Publishers
Rights: fechado
Identifier DOI: 10.1065/jss2008.03.283
Date Issue: 2008
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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