Mineral Processing
Jiaye Li; Jing Zhao; Zebin Wang; Huan Liu; Qing Wen; Jinling Yin; Ze Li; Yang Lei; Guiling Wang
Abstract
Traditional graphite has safety and environmental issues, associated with fluorine purification. To address these issues, an energy-saving and efficient graphite purification process can be explored through the acid leaching method with composite additives. The acid leaching process was studied and optimized ...
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Traditional graphite has safety and environmental issues, associated with fluorine purification. To address these issues, an energy-saving and efficient graphite purification process can be explored through the acid leaching method with composite additives. The acid leaching process was studied and optimized in detail using the controlled variable method including the effects of the soaking time and temperature on the graphite purification process. Then the response surface method was used to simulate the orthogonal experiment of graphite purification to verify the correctness of the single-factor, experiment. The purity and micromorphology of the graphite samples at each stage were characterized and tested. The experimental results showed that the optimal liquid-to-solid ratio of the acid solution and graphite was 20:1, which could make the fixed carbon content reach 99.77%. On the basis of these optimal process conditions, the addition types were further explored. The experimental result showed that the best addition was ascorbic acid and EDTA, which could reduce the content of various impurities in the graphite raw material without destroying the microstructure of the graphite. Benefitting from the addition of compound additives in the two-step process, almost all the metal ions were leached from the graphite. After the acid and water leaching, the fixed carbon content of graphite could reach 99.96%. The process parameters proposed in this paper were scientifically verified by both the single-factor and multi-factor experiments, and innovative and effective additives were introduced in different steps to make the graphite purity break through 99.9%, which was difficult to reach by the traditional method.
Mineral Processing
Satya Sai Srikant; Raghupatruni Bhima Rao
Abstract
The present paper deals with the development of process flowsheet for recovery of high-grade graphite from rougher graphite concentrate for use in industrial applications. In the present investigation, since the coarser graphite flakes have a higher demand, an attempt is made at every stage of comminution, ...
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The present paper deals with the development of process flowsheet for recovery of high-grade graphite from rougher graphite concentrate for use in industrial applications. In the present investigation, since the coarser graphite flakes have a higher demand, an attempt is made at every stage of comminution, and flash flotation experiments have been carried out, and the end product obtained by stage comminution followed by flotation has been further subjected to alkali pressure leaching followed by grinding and flotation to recover industrial grade graphite concentrate. During this stage grinding, an additive, a depressant that is being used for depression of silica during flotation, has been used as grinding aid. The data indicates that at any given time of grind, the effect of grinding aid is significantly better as far as the separation efficiency of graphite. Hence, it is concluded that excessive size reduction of graphite is minimised while using a grinding aid. Based on these observations, further studies have been planned for flash flotation using a comminution circuit with grinding aids. The results of the present study reveals that number of cleaning of rougher concentrate alone will not fetch more than 75% of fixed carbon (FC) with less than 8% yield and 41% recovery. The effect of four stage cleanings continued with starvation dosage in grinding circuit followed by flash flotation indicate that the end product achieved contains 97.8% FC with 11.6% yield and 78% recovery and the overall values loss in tailings contain 3.6% FC. The end product achieved by alkali digestion method from a flotation product [97.8% FC] contains 99.2% FC with overall 10.4% yield and 71% recovery. The process adopted in the present investigation is friendly environment and process flowsheet is an innovative. The end product obtained from this process is useful for various industrial applications.
