“…HCl leaching treatment was used to remove serpentine and clinochlore, while quartz was still present in the conventional leaching concentrate. HCl is commonly inefficient to remove siliceous minerals (such as quartz and clays) from graphite ores [ [26] , [27] ]. Quartz does not react well with HCl, while reacted clays can form inert layers (H 2 SiO 3 ) on graphite surfaces that hinder HCl's contact and reaction with impurities.…”
Section: Resultsmentioning
confidence: 99%
“…These phenomena indicated the presence of impurities between carbon layers. Thus, future attention can be paid to further removing the ash materials from graphite by combining an ultrasound-assisted leaching system and some other intensity techniques such as HCl-hydrofluoric acid leaching [ [27] , [29] ], inorganic acid-fluoride salt leaching[ [30] , [31] ], and oxidation-expansion acid leaching [ [62] , [85] , [86] ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Wang, et al [ 26 ] increased the carbon content of aphanitic graphite from 90.20 % to 99.00 % by combining alkali roasting (1 h roasting time) and acid leaching process (2 h leching time). Kaya and Canbazoğlu [ 27 ] reported that the fixed carbon content of graphite can be increased by ∼ 60 % with 20 % HCl + 4 % HF and 4 h of leaching time. Hong, et al [ 28 ] increased the purity of aphanitic graphite from 87.8 % to 99.1 % by an HCl-HF system after a 4 h reaction time.…”
“…HCl leaching treatment was used to remove serpentine and clinochlore, while quartz was still present in the conventional leaching concentrate. HCl is commonly inefficient to remove siliceous minerals (such as quartz and clays) from graphite ores [ [26] , [27] ]. Quartz does not react well with HCl, while reacted clays can form inert layers (H 2 SiO 3 ) on graphite surfaces that hinder HCl's contact and reaction with impurities.…”
Section: Resultsmentioning
confidence: 99%
“…These phenomena indicated the presence of impurities between carbon layers. Thus, future attention can be paid to further removing the ash materials from graphite by combining an ultrasound-assisted leaching system and some other intensity techniques such as HCl-hydrofluoric acid leaching [ [27] , [29] ], inorganic acid-fluoride salt leaching[ [30] , [31] ], and oxidation-expansion acid leaching [ [62] , [85] , [86] ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Wang, et al [ 26 ] increased the carbon content of aphanitic graphite from 90.20 % to 99.00 % by combining alkali roasting (1 h roasting time) and acid leaching process (2 h leching time). Kaya and Canbazoğlu [ 27 ] reported that the fixed carbon content of graphite can be increased by ∼ 60 % with 20 % HCl + 4 % HF and 4 h of leaching time. Hong, et al [ 28 ] increased the purity of aphanitic graphite from 87.8 % to 99.1 % by an HCl-HF system after a 4 h reaction time.…”
“…Due to the presence of mineral acids in them, current conventional procedures like acid leaching are detrimental to the environment [4]. Hydrochloric acid is the only mineral acid that is safe, but it is inefective for acid leaching [4,18]. Due to innovative uses for the material and possible high future output, there will be an increase in the benefciation of low-quality graphite ore reserves around the world.…”
Due to its numerous and major industrial uses, graphite is one of the significant carbon allotropes. Refractories and batteries are only a couple of the many uses for graphite. A growing market wants high-purity graphite with big flakes. Since there are fewer naturally occurring high-grade graphite ores, low-grade ores must be processed to increase their value to meet the rising demand, which is predicted to increase by >700% by 2025 due to the adoption of electric vehicles. Since graphite is inherently hydrophobic, flotation is frequently used to beneficiate low-grade ores. The pretreatment process, both conventional and unconventional; liberation/grinding methods; flotation methods like mechanical froth flotation, column flotation, ultrasound-assisted flotation, and electroflotation; and more emphasis on various flotation reagents are all covered in this review of beneficiation techniques. This review also focuses on the different types of flotation reagents that are used to separate graphite, such as conventional reagents and possible nonconventional environmentally friendly reagents.
“…It is used in electrical products and as a filler in rubber products, desulphurising agent, anode material in batteries, and conductive coating as well as in bearings, crucibles, electrodes, steel production, and even in the manufacture of cluster bombs and paints. In the era of automotive development, especially hybrid and electric drives, the use of graphite in batteries is of particular importance [6,[8][9][10][11][12][13][14][15][16]. Graphite is also expected to find applications in conductive inks, ultra-thin lighting systems, selectively permeable membranes, and other applications [16].…”
The paper presents the characteristics of products annealing at the temperatures of 2400 and 3000 °C of unburned carbon from coal fly ash in terms of its possible use as a starting material in the graphitization process. An amorphous substance (organic substance) with an admixture of some minerals has been found in samples subjected to graphitization. However, the graphite phase is dominant in products subjected to graphitization. Studies have also shown a diverse grain morphology in individual samples. The presence of plate-shaped and tube-shaped grains was found. As the graphitization temperature of the starting material increases (2400 and 3000 °C), the specific surface area in the graphitization products decreases. The total pore volume in the samples after the graphitization process was significantly lower than the pore volume of active carbons produced from other unburned carbon. Average pore diameter is similar to the pore diameter in active carbons. The reflectance value of the matrix for the sample graphitized at 3000 °C is characteristic for graphite. Unburned carbon from Polish fly ash can be used as the starting material for graphitization.
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