Study On The Preparation Of Al-Si Alloy From Crystalline Silicon Diamond Wire Cutting Waste

In the solar-grade silicon wafer industry chain,the waste slurry produced by the mortar cutting silicon wafer technology has the characteristics of complex composition,huge output,serious pollution,and difficulty in recycling.It has been gradually replaced by diamond wire cutting technology.But diamond wire cutting still has up to 35-40%of silicon in the form of silicon powder mixed in the cutting fluid.Massive production of cutting waste causes a large amount of waste of crystalline silicon and serious environmental pollution,the problem of recycling it must not be delayed.Research on the method of preparing Al-Si alloy using crystalline silicon diamond wire cutting waste can Simple and economical resource recycling silicon waste.Firstly,using scanning electron microscope(SEM),X-ray diffractometer(XRD),X-ray fluorescence spectrum analyzer(XRF)and other instruments to analysis of the chemical composition,physical structure,oxidation properties and other characteristics of crystalline silicon diamond wire cutting waste(DWC).The results show that the composition of DWC is Si,Al,Fe,Ca,Ni,Cu and other elements.The Fourier transform infrared spectrometer result of the oxide in the cutting waste is mainly Si O2,which determined The main smelting equipment is Electromagnetic induction furnace.Secondly,in the experimental stage,DWC is mixed with aluminum particles for induction melting and preparing Al-Si alloy at an electromagnetic frequency of 3KHz.The effects of different aluminum-silicon molar ratios on the recovery rate of silicon in the DWC,the chemical reaction process in the alloying process,the kinetic parameters of the aluminothermal reduction reaction Si O₂,the distribution of impurity elements in the alloying process,and the electromagnetic directional solidification on influence of impurity distribution in the alloying process was investigated.In which using HSC 6.0 software analysis of the thermodynamic reaction and differential thermal analysis.of the kinetic process of Si O₂in aluminum thermal reduction.The results show that the alloying reaction is temperature range of 800?1600?under the electromagnetic stirring.The thermite reaction can reduce the oxide impurities such as Fe₂O₃,Ca O,Si O₂in DWc to metal elemental,and generate Al₂O₃to separate Slag part;The activation energy of thermite reduced silica is 364.1 k J/mol,the reaction order is 0.91,and the alloying effect is obvious;EPMA and XRD analysis of alloy samples show that the composition of alloy and slag phase was completely consistent with the thermodynamic analysis;when the molar ratio of aluminum to silicon was 0.65:0.35,the utilization rate of silicon in DWC could reach83.37%.Directional solidification can separate Fe and Ca impurities to the upper part of the alloy sample and surplus silicon to the lower part of the alloy.The pull-down rate of 5?m/s is better than that of 15?m/s and 25?m/s,and the silicon enrichment area is denser.Finally,in the acid leaching purification stage,the effect of different acid leaching conditions on the removal rate of impurities in the DWC was investigated.In the first stage,the concentration of 4mol/L,leaching time 3h,stirring speed 200r/min,Leaching temperature 40?and liquid-solid ratio 5:1 is the best purification,In the second stage,HF acid deoxidization can reduce the oxygen content to less than 2%After purification,The impurities of Fe and Ca are lower than the detection standard in Al-Si alloy.,and the efficiency of silicon recovery is higher.