Preliminary evaluation of acid mine drainage in Minas Gerais State, Brazil

Mello, Jaime Wilson Vargas de; Dias, Luiz Eduardo; Daniel, Alfredo Mucci; Abrahão, Walter Antônio Pereira; Deschamps, Eleonora; Schaefer, Carlos E. G. R.

doi:10.1590/s0100-06832006000200016

Cited by 11 publications

(6 citation statements)

References 10 publications

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“…On the other hand, ABA data to the samples from Santa Barbara agreed well with mineralogical characterization performed by Mello et al. 27 These authors found pyrrhotite, arsenopyrite and substantial amounts of carbonates in samples from this region.…”

Section: Acid-base Accounting (Aba) and Ph Of The Samplessupporting

confidence: 88%

Arsenic mobilization from sulfidic materials from gold mines in Minas Gerais State

et al. 2008

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Recebido em 21/6/07; aceito em 26/10/07; publicado na web em 15/5/08Acid drainage results from exposition of sulfides to the atmosphere. Arsenopyrite is a sulfide that releases arsenic (As) to the environment when oxidized. This work evaluated the As mobility in six sulfidic geomaterials from gold mining areas in Minas Gerais State, Brazil. Grained samples (<2 mm) were periodically leached with distilled water, during 70 days. Results suggested As sorption onto (hydr)oxides formed by oxidation of arsenopyrite. Low pH accelerated the acid generation, dissolving Fe oxihydroxides and releasing As. Presence of carbonates decreased oxidation rates and As release. On the other hand, lime added to a partially oxidized sample increased As mobilization.Keywords: arsenopyrite; acid mine drainage; contamination. INTRODUCTIONAcid mine drainage (AMD) results from a set of chemical, electrochemical and microbiological reactions, risen from exposure of sulfide bearing geological materials to the atmospheric oxygen and water.1 Under such conditions there is a net generation of sulfuric acid, decreasing pH of the drainage water and increasing solubility and leaching of toxic elements as heavy metals and metalloids.2-4 Consequently, there are increasing risks for toxic metals and metalloids incorporation in biological systems and so, bioaccumulation and biomagnification processes in the trophic chain.Arsenopyrite is a sulfide (AsFeS) commonly found in gold mine areas. 5,6 Its oxidation produces arsenic and sulfur oxiacids (e.g. H 3 AsO 3 , H 3 AsO 4 , H 2 SO 4 ). Arsenic is toxic at low concentrations and sulfuric acid is responsible by the pH drop. 7 The rate of sulfides oxidation depends on several factors, including the amounts of arsenopyrite (e.g. AsFeS), grain size distribution, temperature and the exposure time of the material to the atmospheric water and oxygen. Catalytic action of the Acidithiobacillus aggravates the problem under acid medium, at pH < 3, which stimulates bacterial activity. 8Ingestion of water is considered the main source for As contamination. The most noticeable reports are mass contamination cases that took place in Bangladesh, 9,10 Taiwan 11,12 and Chile. 13 In Brazil, the Iron Quadrangle is one of the affected regions in Minas Gerais State. Most impacted areas are close to gold mines, as in Nova Lima, Raposos, Mariana and Santa Bárbara districts. [14][15][16] Several researchers showed that As adsorption onto iron oxides decreases as the pH increases. [16][17][18][19][20] On the other hand there are reports of increasing As (III) sorption as the pH increases from 3 to the neutral, when the adsorbent is a sulfide as troillite (FeS) or pyrite (FeS 2 ). 21 Release of As from arsenopyrite structure, by oxidation, also decreases at increasing pH, mainly due to the drop of bacterial activity. 8,9 Face to the need for controlling As dispersion in the environment, this research was performed in order to study the mobility of As in samples of sulfidic materials from gold mine areas in different geological sc...

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Section: Acid-base Accounting (Aba) and Ph Of The Samplessupporting

confidence: 88%

Arsenic mobilization from sulfidic materials from gold mines in Minas Gerais State

et al. 2008

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“…This relation between pH and soluble concentrations of Fe and As is much more evident at higher initial As concentrations. It also corroborates the close association between As and Fe (hydr)oxides as revealed by de Mello et al (2006) for soils from a gold-mining region in Brazil.…”

Section: Ph and Iron Concentrations In Supernatantssupporting

confidence: 84%

Effectiveness of Ferric, Ferrous, and Aluminum (Hydr)Oxide Coprecipitation to Treat Water Contaminated with Arsenate

et al. 2018

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Coprecipitation of Fe and Al (hydr)oxides has been considered a low‐cost process to remove As from wastewater. Arsenate is the most stable form of As in aerobic environments such as surface water, soils, and sediments and can be removed from water through methods based on this process. Iron/aluminum molar ratios of 100:0, 80:20, and 60:40 were used to treat water contaminated with As at concentrations of 50 and 500 mg L−1. Aluminum, ferrous, and ferric sulfates were used to coprecipitate Al and Fe (hydr)oxides at high pH. Maghemite, magnetite, lepidocrocite, and goethite were detected in precipitates from Fe(II), whereas hematite and ferrihydrite were identified in Fe(III) treatments. Segregation of Al (hydr)oxides as gibbsite and bayerite as well as the Al isomorphic substitution in Fe (hydr)oxides were detected in the presence of Al. The precipitates were classified as nonhazardous according to the leaching test based on Brazilian Technical Standard NBR 10005. The presence of Al increased the stability of the sludge from Fe(II) treatments but did not affect the stability of precipitates from Fe(III) treatments. High efficiencies for As removal from water were obtained for all treatments, but concentrations of soluble As were, in general, lower for Fe(III) treatments especially, in the absence of Al. Treatments were efficient in reaching the threshold to effluent discharge (0.5 mg L−1), but only treatments with initially 50 mg L−1 of As reached the threshold for drinking water (10 μg L−1). Core Ideas Up to 500 mg L−1 of arsenate in water could be removed with coprecipitation. Sludge from coprecipitation of As with Fe and Al (hydr)oxides is safe to dispose. Fe (III) is better than Fe (II) to remove soluble As at higher concentrations.

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“…For instance, in the case of an abandoned gold and www.nature.com/scientificreports www.nature.com/scientificreports/ silver mine in Japan with an AMD flow of 18,000 m³/year 70 , it would take approximately 900 t/year of dregs or grits to treat the drainage. The mining activity in Minas Gerais state in Brazil has a potential for generating 104 billion cubic meters of AMD annually, with a cost of US$ 26 million for using commercial limestone in AMD remediation 71 .…”

Section: Resultsmentioning

confidence: 99%

Kraft pulp mill dregs and grits as permeable reactive barrier for removal of copper and sulfate in acid mine drainage

Farage

Quina

Gando-Ferreira

et al. 2020

Sci Rep

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Mining is an essential human activity, but results in several environmental impacts, notably the contamination of ground and surface water through the presence of toxic substances such as metals and sulfates in mine drainage. permeable reactive barriers (pRB) have been applied to remediate this environmental impact, but the high costs associated with the maintenance of this system are still a challenge. the main objective of this study was to evaluate the use of kraft pulp mill alkaline residues, known as dregs and grits, as material for pRB, and to determine their capacity for retaining copper and sulfate. the work was carried out in laboratory adsorption kinetics assays, batch assays and column tests. tests for elemental characterization, point of zero charge, acid neutralization capacity, total porosity, bulk density and moisture of the dregs and grits were conducted. the results showed high retention of Cu due to a chemical precipitation mechanism, notably for dregs (99%) at 5 min in adsorption kinetics. The grits presented similar results after 180 min for the same assay. Sulfate retention was effective at pH below 5, with an efficiency of 79% and 89% for dregs and grits, respectively. Dregs presented the best results for acid drainage remediation, notably with a solid:liquid (S:L) ratio of 1:10.Acid mine drainage (AMD) is caused by the oxidation of sulfur-bearing materials in the presence of oxygen and water, resulting in sulfate and metals solubilization and forming acidic solutions 1-4 . Active and inactive mining activities for metals, such as copper, lead, zinc, gold, silver and uranium, provoke potential degradation of the environment by the presence of different contaminants, particularly due to metals and sulfates in acid drainage 5 . Indeed, the acid drainage formation is an important environmental aspect of mining practices. The sulfate concentrations may reach 2,400 to 20,800 mg/L 6,7 , well above the limit of 250 mg/L established by the World Health Organization 8 . It might cause damage not only to human health but also to the environment, and depreciation of structures and equipment 2,9 , resulting in high costs for control and management by the mining companies 2,10 . Copper concentration may be in the range from 77 to 615 mg/L, with higher values in the Cu mines 1,11 . Other metals such as Al, Mn, Fe, Mg, and Zn are also commonly found in AMD in these mines 10,12 .AMD remediation can be actively accomplished off-site with the pumping of the contamination plume to a treatment plant, or passively on-site with the use of permeable reactive barriers (PRB), with lower installation and maintenance costs. It can be carried out with the flow directed to the system, by the Funnel model, or the grid-type, by the installation of a perpendicular barrier to the contamination plume 13,14 . The PRB was first proposed in Canada in the 1990s 13,15 , with different materials used as adsorbent media, from single barriers with only one material to composites of different materials, or multiple sequential barrier...

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Preliminary evaluation of acid mine drainage in Minas Gerais State, Brazil

Cited by 11 publications

References 10 publications

Arsenic mobilization from sulfidic materials from gold mines in Minas Gerais State

Arsenic mobilization from sulfidic materials from gold mines in Minas Gerais State

Effectiveness of Ferric, Ferrous, and Aluminum (Hydr)Oxide Coprecipitation to Treat Water Contaminated with Arsenate

Kraft pulp mill dregs and grits as permeable reactive barrier for removal of copper and sulfate in acid mine drainage

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