Carbon thermal reduction is used to enrich alumina from fly ash and prepare ferrosilicon alloy
The comprehensive utilization of fly ash is a solid waste industry with high technical content and application potential,which integrates environmental protection and resource recycling.Ferrosilic-on alloy was prepared by carbothermal reduction of fly ash under laboratory conditions and alumina was enriched to recover Si,Fe,Al and other elements in fly ash.It was found that the content of silicon in the ferrosilicon alloy increased with the increase of temperature during the reaction.When the carbon content increases,the Al-O-Si bond of the mullite phase in the fly ash is more easily decomposed and reduced to alumina and silica.The carbothermal reduction is carried out under the condition of adding Fe2O3.After adding Fe2O3,not only the temperature of carbothermal reduction can be reduced,but also the silicon dioxide in mullite phase is easier to be reduced to silicon,and combined with metal iron to form ferrosilicon alloy,which creates conditions for the subsequent separation of ferrosilicon alloy and alumina.In this process,fly ash,iron oxide and pulverized coal are mixed at a mass ratio of 5:4:2,and roasted in a resistance furnace at 1 600 ℃.After holding for two hours,they are cooled with the furnace.After crushing,screening,grinding and magnetic separation,the reduced materials are treated to obtain ferrosilicon alloy primary products and tailings with high alumina content.The desilication rate reaches 76.44％,and the recovery rate of aluminum reaches 93.96％.
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