The recycling and reuse of calcium carbide slag for the preparation of high-quality activated calcium oxide(CaO)is one of the effective ways to achieve its efficient use,but the complex composition and high silicon content of calcium carbide slag restrict the product quality of the preparation of activated calcium oxide.Based on the distribution law and occurrence form of silica impurities in calcium car-bide slag,the effect of flotation agents on the removal of silicon in calcium carbide slag were systematically investigated,a suitable desili-cation reagent for calcium carbide slag was obtained,the changes in elemental composition of calcium carbide slag and the changes in the properties of active calcium oxide products after roasting before and after flotation were studied,and a process route for the preparation of calcium oxide by flotation desilication coupled with roasting of calcium carbide slag was put forward.The results indicate that calcium hydroxide is the main component of calcium carbide slag,which also contains some silicon impurities such as silica and aluminosilicate.Through a reverse flotation desilication test combined with sodium hexametaphosphate of 400 g/t and dodecylamine of 125 g/t,the sili-ca mass fraction of calcium carbide slag is reduced from 3.14%to 2.85%,and the calcium recovery rate reaches 87.9%.The calcium car-bide slag after flotation separation of silica impurities could be completely converted into calcium oxide after roasting at 900℃,and the calcium oxide mass fraction in the product is 94.46%,the compressive strength is increased from 3.17 MPa to 3.87 MPa,and the met-allurgical activity is increased from 341.6 mL to 385.5 mL,and the product performance is improved.The above research can provide ref-erence for the recycling of calcium carbide slag.
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