J. Jurković; E. Babajić; T. Muhić – Šarac; M. Kolar; A. Kazlagić
Abstract
Oxidation of sulfide-containing ores is the main cause of Acid Mine Drainage (AMD), which is an environmental problem associated with both the abandoned and active mines. Iron-bearing sulfide minerals can be oxidized and form mine waters with high sulfate content, low pH, high electrical conductivity, ...
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Oxidation of sulfide-containing ores is the main cause of Acid Mine Drainage (AMD), which is an environmental problem associated with both the abandoned and active mines. Iron-bearing sulfide minerals can be oxidized and form mine waters with high sulfate content, low pH, high electrical conductivity, high redox potential, and high concentrations of iron, aluminum, and other heavy metals. In the process of AMD, precipitation of poorly crystalized oxy-hydroxides of iron with a large active surface can occur. On the surface of iron oxy-hydroxide, the precipitated particulate matter, anions, and cations (metals) could be adsorbed. Mine waters can contain a certain amount of precious metals that can also be adsorbed onto an iron particulate matter surface, which is investigated in this research work. In this work, the samples of iron oxy-hydroxide particulate matter at abandoned gold mine waste in Bakovići (Central Bosnia and Herzegovina) are used. Several parameters including pH, water content, particle size distribution, sulfate content, electrical conductivity, redox potential, and amounts of gold, silver, and iron are measured on the selected mine waste samples. The results obtained indicate that significant amounts of gold (average: 6.8 mg/kg) and silver (average: 7.13 mg/kg) are present in the iron precipitate. Adsorption of precious metals onto the iron oxy-hydroxide surface is strongly pH-dependent. At a very low pH value, desorption of precious metals is favorite. Thus, precious metals are only partially adsorbed onto the iron oxy-hydroxide surface.
Bahman Ghobadi; Mohammad Noaparast; Seid Ziaedin Shafaei; Majid Unesi
Abstract
This study investigates the optimization of gold dissolution from Aghdarre ore. Therefore, a laboratory investigation was initiated, to improve the leaching conditions with the objective of maximizing mill capacity with no reduction on gold recovery. It was observed that the time reduction from 25 to ...
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This study investigates the optimization of gold dissolution from Aghdarre ore. Therefore, a laboratory investigation was initiated, to improve the leaching conditions with the objective of maximizing mill capacity with no reduction on gold recovery. It was observed that the time reduction from 25 to 15 hours did not change the gold recovery. In the other words, it indicated that a capacity of 140t/h can be sustained without detrimental effect on gold recovery. The optimum parameters were 700g/t NaCN, 46% solid in pulp, pH=10, and d80=45 microns using the Taguchi method. So, the gold recovery was obtained 90.71%. Also, it was concluded that the NaCN concentration was the most effective parameter and the solid percent plus retention time had the lowest effects on this process.
Saeed Alishahi; Ahmad Darban; Mahmood Abdollahi
Abstract
Since a high toxicity of cyanide which use as a reagent in the gold processing plant, thiosulfate has been recognized as a environmental friendly reagent for leaching of gold from ore. After gold leaching process it's important for recovery of gold from solution using adsorption or extraction methods, ...
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Since a high toxicity of cyanide which use as a reagent in the gold processing plant, thiosulfate has been recognized as a environmental friendly reagent for leaching of gold from ore. After gold leaching process it's important for recovery of gold from solution using adsorption or extraction methods, One of these methods is activated carbon.The loading of gold from industrial thiosulfate solution that obtained from Zarshuran gold plant-Takab-Iran, onto activated carbon have been investigated. The affecting variables of the adsorption of gold on the carbon included, temperature, concentration of gold, size of activated carbon, pH and the ratio of amount of activated carbon to the volume of solution. The results have shown that at low concentration of gold, effective loading can be achieved at pH 10.5. The size of activated carbon has a significant effect on the loading of gold. In this research the recovery of gold on activated carbon has been predicted using artificial neural network. For this purpose temperature, pH, the proportion of solution volume to weight of activated carbon, gold concentration and time of adsorption were taken as input parameters, whereas, the recovery of gold on activated carbon from thiosulfate solution was considered as an output parameter. The network with LMBP algorithm with two hidden layer were used and the topology 5-4-13-1 showed the best ability for prediction.Moreover sensitive analyze were indicated parameters pH and temperature have substantial influence on adsorption.