Z Boroumand; S Ghassa; M Moradian; H Abdollahi; Gh Fathabadi; K Fakhremoghadam
Abstract
In this research, the bioleaching process of mixture of sulfide and carbonate zinc and lead ore of Angouran Mine, whit local mixed mesophilic bacteria was studied. The purpose of this study was to indicate the effects of pulp density, Fe(II) concentration and initial pH in the zinc and lead bioleaching. ...
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In this research, the bioleaching process of mixture of sulfide and carbonate zinc and lead ore of Angouran Mine, whit local mixed mesophilic bacteria was studied. The purpose of this study was to indicate the effects of pulp density, Fe(II) concentration and initial pH in the zinc and lead bioleaching. In Addition, the pH and Reduction-Oxidation Potential (ORP) have been monitored and evaluated during bioleaching process. The results showed that the zinc recovery through the bioleaching process (64.4 %) was much more than the leaching without bacteria (33.56 %). The results also showed, an increase in the pulp density caused a decrease in zinc recovery, and an increase in initial pH and ferrous concentration increased the zinc recovery. On the other hand, maximum lead recovery was 1.03 %. The study of bioleaching residual showed that the lead was recrystallized as Pb5(AsO4)3Cl. However, presenting the relation between mentioned parameters and Pb recovery was impossible due to lead precipitation. The results of this research could be used for bioleaching of high-grade Pb-Zn ores.
M.A Shabani; M Irannajad; A.R Azadmehr
Abstract
Copper oxide ores are usually leached in sulphuric acid solution. However, it has severe adverse impact on the environment. In this study, bioleaching and leaching by citric acid, as environmentally friendly methods, are investigated. The experiments were carried out on a copper oxide ore sample containing ...
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Copper oxide ores are usually leached in sulphuric acid solution. However, it has severe adverse impact on the environment. In this study, bioleaching and leaching by citric acid, as environmentally friendly methods, are investigated. The experiments were carried out on a copper oxide ore sample containing copper content of 3.4%. This sample does not contain any energy source to grow the conventional bioleaching microorganisms (like Thiobacillusferrooxidans and Thiobacillusthiooxidans). This sample was leached by a heterotrophic bacterium, Pseudomonas aeruginosa. This bacterium produces organic acids in selected culture medium that operate as leaching agents. Leaching is investigated by citric acid, as an organic acid produced by this microorganism. The optimum bioleaching conditions were found as: glucose percentage of 6, bioleaching time 8 days and solid/liquid ratio of 1:80 and of optimum leaching conditions as: particle size range105-150µm, acid concentration of 0.2 M, 30 min dissolution time, solid/liquid ratio of 1:20 g/mL and temperature of 40°C. Under optimum bioleaching conditions 53 percent of copper was extracted and copper extraction under optimum leaching conditions was 92 percent.
H. Atashy; J. Rahnama-Rad
Abstract
The effect of temperature, mixer ratio and acid thickness on the rate of magnesite dissolution in nitric acid was investigated in this laboratory research. The result shows dissolution rate increases with rising temperature when the size of particles is reduced. At ...
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The effect of temperature, mixer ratio and acid thickness on the rate of magnesite dissolution in nitric acid was investigated in this laboratory research. The result shows dissolution rate increases with rising temperature when the size of particles is reduced. At the beginning of the reaction, thicker acid increases the rate of dissolution but as the acid grows thicker not only there is no overwhelming changes obvious but also extends the duration due to product layer formed on the mineral grain surface during the reaction. This has less effect on thinner acid and smaller particles. The kinetic results shows that magnesite minerals dissolution in nitric acid follows the kinetic model , Optimized laboratory conditions are a temperature of 30 oC, nitric acid thickness of 50 %, size of particles: 250-297 ., mixer ratio of 300 rounds per min. and reaction duration of 170 min.
M. Moazemi Goodarzi; B. Rezaei; A. Amini
Abstract
In this paper, iron removal studies on high iron diasporic bauxite by thermochemical treatment was investigated for the first time. For this purpose, bauxite samples were calcined in temperatures between 600 and 1100°C and then leached with hydrochloric acid. Obtained results revealed, in spit of ...
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In this paper, iron removal studies on high iron diasporic bauxite by thermochemical treatment was investigated for the first time. For this purpose, bauxite samples were calcined in temperatures between 600 and 1100°C and then leached with hydrochloric acid. Obtained results revealed, in spit of gradual decrease in both iron and aluminum extraction with rising calcination temperature, iron extraction to aluminum extraction is selective at calcination temperature above 900°C. Leaching studies of calcined sample at 900°C proved that leaching temperature is the most important parameter for iron dissolution in acid and rising leaching temperatures from 20 to 95°C increases iron extraction over 70%. The other optimum parameters are: leaching time120 minutes, acid concentration 50% V/V, grinding size of 210 µm, pulp density of 15% solid by weight. As a result of optimizing parameters, 96.5% of bauxite iron content removed successfully with 88.5% aluminum recovery and solid residue iron content, i.e., the obtained concentrate, decreased from 27.02 to 1.59%.
