M. Hosseini Nasab; M. Noaparast; H. Abdollahi
Abstract
In this research work, the bio-leaching of Co and Ni from an iron-rich laterite ore is assessed using the acidophilic heterotrophic (Delftia acidovorans)and autotrophic (Acidithiobacillus ferrooxidans) bacteria. The metabolic products of the acidophilic bacteria play an important role in bio-leaching. ...
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In this research work, the bio-leaching of Co and Ni from an iron-rich laterite ore is assessed using the acidophilic heterotrophic (Delftia acidovorans)and autotrophic (Acidithiobacillus ferrooxidans) bacteria. The metabolic products of the acidophilic bacteria play an important role in bio-leaching. The results obtained from the indirect bio-leaching indicate the highest nickel recoveries of up to 83.65% and 80.18%, respectively, by the supernatants of Acidithiobacillus ferrooxidans and Delftia acidovorans, both measured at 90 °C for 3 h with a stirring speed of 370 rpm and S/L of 0.1, while the corresponding cobalt recovery rates have reached 86.93% and 83.94%, respectively. The iron dissolution rates in these conditions for the two studied bacteria are 64.34% and 54.41%, respectively. The nickel and cobalt extractions by the indirect bio-leaching of Delftia acidovorans are, respectively, 29.84% and 23.75% higher than those for the direct bio-leaching, performed at 30 °C and 150 rpm of an incubator shaker for 30 days. For the indirect bio-leaching, the chemical control has a larger influence on the dissolution rate of the iron-rich laterite compared to the diffusion control. The activation energies of nickel and cobalt in the chemical control model are 40.07 and 39.08 kJ/mol, respectively.
H. A. Mirzaei; M. Noaparast; H. Abdollahi
Abstract
The precipitation of aluminum hydroxide from a supersaturated sodium aluminate solution is known as an essential production step in the Bayer process. In this work, the real precipitation process in the Iran Alumina Plant was modeled by the historical data with the help of Design Expert. According to ...
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The precipitation of aluminum hydroxide from a supersaturated sodium aluminate solution is known as an essential production step in the Bayer process. In this work, the real precipitation process in the Iran Alumina Plant was modeled by the historical data with the help of Design Expert. According to the results obtained, the recovery is significantly improved with decrease in the super-saturation factor (α) of the solution. However, this modification was found to be the most difficult change due to the operational problems. The results obtained indicated the significant impact of the seed size on the product size. The negligible effects of the other parameters involved on controlling the amount of fine grains (< 44 µm) and coarse grains (> 150 µm) in the product showed the significance of reactivating the classification and agglomeration sections. Ultimately, it was found that the recovery process could be enhanced from 46.32% to 47.86% at a constant α by increasing the seed concentration to 400 g/L, increasing the retention time by adding two precipitation tanks and reducing the temperature of the last precipitation tank by 2 ºC (by reducing the temperature of the inlet suspension), while preserving the quality of the product.
M. Hosseini Nasab; M. Noaparast; H. Abdollahi
Abstract
Due to the decreasing production of nickel and cobalt from sulfide sources, the Ni and Co extraction from the oxide ores (laterites) have become more prevalent. In this research work, the effects of calcination prior to leaching, acid concentration, percent solid, pH, and stirring speed on the nickel ...
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Due to the decreasing production of nickel and cobalt from sulfide sources, the Ni and Co extraction from the oxide ores (laterites) have become more prevalent. In this research work, the effects of calcination prior to leaching, acid concentration, percent solid, pH, and stirring speed on the nickel and cobalt recoveries from an iron-rich laterite ore sample were investigated using different organic acids. Then the response surface methodology was implemented in order to optimize the various parameters. By the design of experiments, the compound optimal concentrations of the three different organic acids (gluconic acid: lactic acid: citric acid with a ratio of 1:2:3) were 3.18 M, and S/L = 0.1, pH = 0.5, and the stirring speed = 386 rpm. With the aid of kinetic studies, a temperature of 75 °C, and a test time of 120 minutes, the highest nickel and cobalt recoveries were 25.5% and 37.6%, respectively. In the optimal conditions, the contribution of the percent solids to the nickel recovery was the most and negative, after which the contribution of pH was negative, and finally, the acid concentration had a positive effect. In the optimal conditions, the acid concentration, pH, and solid content were, respectively, important in the cobalt recovery. The SEM results showed that the surface of feed and residue particles in the optimal conditions was not significantly different, and the laboratory data was fitted to a shrinking core model. The results obtained indicated that the reaction rate was controlled by the diffusion reaction at the particle surface, and the activation energies of 11.09 kJ/mol for nickel and 28.04 kJ/mol for cobalt were consistent with this conclusion
Mineral Processing
V. Radmehr; Seyed Z. Shafaei; M. Noaparast; H. Abdollahi
Abstract
This paper presents a new approach for flotation circuit design. Initially, it was proven numerically and analytically that in order to achieve the highest recovery in different circuit configurations, the best equipment must be placed at the beginning stage of the flotation circuits. The size of the ...
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This paper presents a new approach for flotation circuit design. Initially, it was proven numerically and analytically that in order to achieve the highest recovery in different circuit configurations, the best equipment must be placed at the beginning stage of the flotation circuits. The size of the entering particles and the types of streams including pulp and froth were considered as the basis for specialization of the flotation processes. In the new approach, the flotation process plays as the two functions of primary and secondary concentrations. The proposed approach was applied to a lead flotation circuit of a lead-zinc flotation plant. The results obtained showed that in most traditional-oriented circuits, a large part of the streams containing valuable metals were returned to the rougher stage, which, in turn, reduced the efficiency and caused perturbation. In the new approach, providing more control over unit operations in the circuit could provide a higher performance. In addition, in cases where zinc minerals are liberated from their gangue in coarse size, the new approach, by generating coarse-grained tailing, can prevent excessive grinding of zinc minerals in the feed into the zinc flotation circuit.
Mineral Processing
M. Salehfard; M. Noaparast; Seyed Z. Shafaei; H. Abdollahi
Abstract
A lead-zinc carbonate ore sample containing 2.5% Pb and 9.39% Zn was used in this research work. The sample was prepared from the Darreh-Zanjir mine located in the Yazd province (Iran). Influences of the influential factors on flotation of smithsonite and cerussite were investigated. Among the different ...
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A lead-zinc carbonate ore sample containing 2.5% Pb and 9.39% Zn was used in this research work. The sample was prepared from the Darreh-Zanjir mine located in the Yazd province (Iran). Influences of the influential factors on flotation of smithsonite and cerussite were investigated. Among the different parameters involved, dosages of the dispersant, depressants, sulfidizing agent, and collectors de-sliming prior to lead or zinc flotation were essential for the effective recovery and grade of the Zn and Pb flotation concentrates. In addition, the anionic, cationic, and mixed (cationic/anionic) collectors were employed for flotation of smithsonite. The results of reverse and cumulative flotation of both Zn and Pb were relatively low in comparison with the direct process without depressant. Flotation of smithsonite using mixed collectors (Armac C+KAX) showed promising results. Also dosages of chemicals in the cleaning stage for the Zn and Pb concentrates were optimized, and finally, after the cleaner stage for both lead and zinc, a cerussite concentrate with Pb grade and recovery of 49.82% and 60.06%, respectively, and smithsonite concentrate with Zn grade and recovery of 35.47% and 68.56%, respectively, were obtained under the optimal conditions. Furthermore, kinetics of Zn and Pb oxide mineral flotations in the rougher and cleaner stages were studied, which showed that some kinetics models, especially the classical first-order model, could predict the flotation behaviour of the Zn and Pb oxide minerals.
M. Shamsi; M. Noparast; Seyyed Z. Shafaie; M. Gharabaghi; S. Aslani
Abstract
Copper smelting slags are hard materials. Therefore,to recover their copper by flotation method, grinding should be carried out to obtain optimal particle size. Copper smelting slags in the Bardeskan district, with work index of 16.24 kwh/st, were grinded for 65 minutes to reach an acceptable degree ...
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Copper smelting slags are hard materials. Therefore,to recover their copper by flotation method, grinding should be carried out to obtain optimal particle size. Copper smelting slags in the Bardeskan district, with work index of 16.24 kwh/st, were grinded for 65 minutes to reach an acceptable degree of freedom for the flotation tests, with particle size of 80%, smaller than 70 μm. With this grinding time, degree of freedom for copper-bearing minerals was achieved 85-90%. The floatation method performed and the procedure used for the optimization of the effective parameters were described in this paper. The results obtained for the flotation tests, carried out at the optimal conditions after grinding the slags (with a grinding time of65 minutes), showed 62.23% of copper recovery, while, by flotation of copper slags at optimal conditions after increasing the grinding time to 85 minutes (d80 = 48µ), the Cu recovery was increased to 79.89%.
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.
Negar Saeidi; Dariush Azizi; Mohammad Noaparast; Soheila Aslani; R Ramadi
Abstract
In this paper, iron ore sample from the Chadormalu was investigated to determine some comminution properties. Chadormalu deposit is one of the largest iron ore mine in Iran, which is located in Yazd province. The representative ore sample contained 57%Fe, 0.9%P and 0.17%S. The sample was crushed; afterward, ...
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In this paper, iron ore sample from the Chadormalu was investigated to determine some comminution properties. Chadormalu deposit is one of the largest iron ore mine in Iran, which is located in Yazd province. The representative ore sample contained 57%Fe, 0.9%P and 0.17%S. The sample was crushed; afterward, it was ground in various grinding times according to the Bond Ball mill approach to specify the work index values. Based on different grinding times and the obtained results, a new work index equation was then simulated through which grinding time was considered as the main variable. The relationships between work index, the work input and P80 were then concluded. In addition, the results of tests were then used to estimate the selection function parameter. A new equation was applied to determine energy efficiency which could be implemented for energy consumption calculation. Two equations for EB and EB/Elimit were then obtained, where EB is the efficiency of comminution, and the ELimit is the maximum limiting energy efficiency for particle fracture under compressive loading. These equations could estimate the parameters of the iron ore would be precisely estimated. Indeed, by means of work index value; some crushing and grinding characteristics of the taken sample were assessed by which comminution circuit would be designed much better.
A Atrafi; H Hodjatoleslami; Mohammad Noaparast; Z Shafaei; A Ghorbani
Abstract
This study aimed to explore concentration of a low grade sulfide-oxide lead-zinc sample containing 2.3% Pb, 1.91% Zn taken from Changarzeh mine, South Natanz, Iran. The effects of different parameters such as type and dosage of collector, milling retention time, dosage of sodium sulfur and its preparation ...
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This study aimed to explore concentration of a low grade sulfide-oxide lead-zinc sample containing 2.3% Pb, 1.91% Zn taken from Changarzeh mine, South Natanz, Iran. The effects of different parameters such as type and dosage of collector, milling retention time, dosage of sodium sulfur and its preparation time, application of sodium silicate, pH and solid content were investigated in relation to flotation efficiencies. Optimum experiment was carried out in cumulative flotation with 200g/t KAX as collector, 2000g/t Na2S, 500g/t sodium silicate, 30g/t MIBC and at pH=10. This test yielded 94% of lead recovery under optimum condition performance, and a concentrate with 70%Pb was produced through cleaning stages. Eighteen minutes was found to be the optimum time for lead flotation in laboratory scale. Application of gravity method for the production of a middle product was also considered. For shaking table the effect of table slope and water flowrate and for jig the effect of water flowrate and frequency were studied. Gravity separation by shaking table resulted in a concentrate with 46%Pb and 80% recovery, so shaking table could be proposed for production of pre-concentrate.
