| The carbon reducing agent is one of the materials for the metallurgical grade silicon production. However, It metallurgical grade silicon production about 1.5t reducing agent will be consumed, accounted for 25%-30% of the total cost of metal silicon production.The quality of the reductant will determine the quality of the products. Bituminous coal is a very suitable choice to instead of charcoal as the reductant in metallurgical grade silicon proportion, but it ash content too higher. If the ash content of bituminous coal can be decreased by reasonable method and as the reductant used in metallurgical grade silicon production process, it will has a broad application prospects.In this paper, bituminous coal provided by Panxian area of Liu Pan Shui city in Guizhou province ware studied. industrial analysis and XRD qualitative analysis show that the fixed carbon content of the coal sample was 54.58%, ash 14.78%, and the main components of ash content was SiO2 and Al2Si2Os(OH)4, in addition, it also components Fe3O4, Fe2O3 and Al4Si2CaO10(OH)2. The coal sample can’t used to metallurgical grade silicon production under this condition.Density of coal samples analyzed shows that less thanl.4g·cm-3 coal sample cumulative yield is 51.18% and cumulative ash is 6.01%, the coal can obtain higher yield and low ash content clean coal by flotation.The effect of frother, collector and inhibitor on yield and ash of clean coal were investigated in flotation deashing experiment. Select coal sample grain size less than -0.074mm content 50% as the experimental material, slurry concentration was 25% (coal 500g, add water to the 1.5L), The cleaned coal yield reached 58.22%, ash content 4.68% and combustible material recovery is 65.12% under the optimal condition of depressant Na2SiO3 is 2300g/t, terpenic oil as frother is 120g/t, collector diesel oil dosage of 600g/t and through three roughing and two cleaning flotation process. The ash-reduction and iron removal experiments decreased the ash further. The industrial analysis proved the main component is SiO2 and silicate in the ash, total iron content is 6.85%.The influence of acid type, acid concentration, reaction temperature, reaction time, ratio of liquid to solid for clean coal ash and iron leaching rate ware researched. The results showed that hydrochloric acid is better than the sulfuric acid leaching effect, the ash of the coal get from flotation can be reduced to below 5% and the leaching rate of iron is about 90%, fixed carbon content of coal reached 68.78% can be obtained under the optimal condition of liquid to solid ratio 5:1, the concentration of hydrochloric acid is 4mol/L, the reaction temperature is 60℃ and the reaction time is 60min. The properties of clean coal is better than charcoal which carbon content is 65% and ash is 6%.Preparation and performance of the pellet preparation by clean coal ware Studied,The results show that the average cold compressive strength of 5.65MPa, hot compressive strength is 0.76MPa, drop strength sieve sample mass accounted for an average 86.78%, the porosity is 18.22%, specific resistance of 751.17μΩm and carbon content is 65.34%, practical ash is less 5%, compared with charcoal chemical reaction activity of CO2 is only less 1.2% on 1100℃ pellet reduction agent can be obtained under the condition of GY as the binder, forming pressure is 20MPa, the moisture is 5%, add water 8%. It can be used as metallurgical grade silicon production with a reducing agent. |
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