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- Bahrami, Ataallah, et al.
(författare)
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The effect of grinding circuit efficiency on the grade and recovery of copper and molybdenum concentrates
- 2022
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Ingår i: Energy Sources, Part A. - : Taylor & Francis Group. - 1556-7036 .- 1556-7230. ; 44:3, s. 8121-8134
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of grinding and flotation process in copper-molybdenum processing circuit, largely affected by performance of thickeners and hydrocyclones devices. The goal of this paper is to investigate the effect of the rate-limiting factors on the performance of these devices and consequently on grinding and separation efficiency of the molybdenum processing circuit. So, a full process mineralogical study have been carried out on outputs of thickeners and hydrocyclone of the molybdenite flotation circuit. According to the results, coarse-grained fractions (>50 μm) of the planar molybdenite will not necessarily be recovered by thickener and hydrocyclones. This is especially true for hydrocyclones when the inlet-load rate is high, i.e., the erroneous discharge of planar molybdenite particles from the overflow of hydrocyclone, as well as their floatability in the thickener overflow, can be attributed to the effect of particle shape and size. This issue harms the grade and recovery of flotation due to the increase in the amount of circulating load (regrinding) and consequently the generation of fine particles (<10 μm) in the hydrocyclone-milling circuit. On the other hand, the almost spherical particles of copper minerals, as well as the nonplanar molybdenite fine-grained particles, are easily removed from the hydrocyclone underflow or settled in thickeners. The introduction of copper mineral particles into molybdenum concentrate and vice versa has reduced the quality of the produced concentrate and undesirable flotation performance.
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| 2. |
- Bahrami, Ataallah, et al.
(författare)
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The Evaluation of Starch-Based Flocculant on the Thickener Operation in the Molybdenum Processing Plant and Competency of Molybdenite Flotation
- 2022
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Ingår i: Mining, Metallurgy & Exploration. - : Springer. - 2524-3462 .- 2524-3470. ; 39:3, s. 1255-1266
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Tidskriftsartikel (refereegranskat)abstract
- The type and dosage of flocculants used in the middle thickener of the copper-molybdenum plant, in addition to adjusting the quality of recycled process water, is very effective on the floatability of molybdenite. In this study, the effect of starch-based flocculant (wheat starch) was investigated on the efficiency of middle thickener and molybdenite flotation, in the molybdenum processing plant. First, sampling from overflow and underflow of the middle thickener in Mo processing circuit (in industrial scale), in the presence and absence of starch, were collected. The polished sections of samples from the overflow and underflow of the thickener were studied in order to determine the effect of starch on particles settling with different shapes. Microscopic studies show that molybdenite plate-like coarse particles are transferred to the thickener overflow (process water) in the presence of starch flocculant, whereas molybdenite fine particles present in the underflow are often needle-shaped. In addition, in terms of grade distribution, the grade of molybdenum in the thickener overflow is higher than that of copper and iron. Then, after sedimentation tests (in laboratory scale) with different concentrations of flocculant, flotation tests were performed on test samples. According to the results from laboratory studies, increasing the dosage of starch from 0 to 1000 g/t increased the recovery of molybdenite flotation and reduced the access of copper minerals to molybdenite concentrate. In this case, molybdenum recovery (in lab tests) is increased by about 5% compared to the case of not using starch. While the increase in the recovery of molybdenum by adding starch to the middle thickener in the industrial scale is about 10%. In higher dosages of starch (2000 g/t), the trend is reversed (in the lab and industrial scale) and molybdenum recovery decreased sharply due to the decrease in contact angle and depression, whereas the amount of copper transferred to the molybdenum concentrate increased.
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