The recycling of calcium carbide slag-calcium oxide-calcium carbide is an effective way to realize the recycling of calcium carbide slag. However, due to the complex composition of calcium carbide slag and the difficulty of purification, large-scale preparation ofactive calcium oxide for recycling has not been achieved at present. In this paper, the changes in phase morphology during the calcinationprocess of calcium carbide slag were systematically investigated, and the composition differences of calcium carbide slag with different particle sizes were studied. By studying the particle size characteristics of calcium carbide slag and the roasting characteristics of calcium carbide slag of each particle size, the influence of particle size classification on the preparation performance of active calcium oxide from calcium carbide slag was clarified. The results show that the impurities in carbide slag are concentrated in the particles less than 45 μm andlarger than 180 μm, and the acid insoluble matter, Fe and C, etc. are mainly concentrated in the particles more than 150 μm. The calcium component is gradually transformed into calcium oxide in two stages ranging from 350 to 460 ℃ and 550 to 720 ℃ during the roastingprocess. Most of the carbonaceous impurity particles can decompose below 800 ℃ , which affects the performance of preparing activated calcium oxide products. The compressive strength of activated calcium oxide is mainly affected by particle size, and the metallurgicalactivity is jointly affected by particle size and composition. The fine particles will fill the intergranular gap during the pressing process, increasing the strength but hindering water penetration. Excessive impurities in coarse particles are difficult to decompose and form largepores, affecting the strength and activity of products. 45-106 μm is more suitable for the preparation of active calcium oxide, with an activity of 411 mL (4 mol/ L standard hydrochloric acid) and the compressive strength of 2.46 MPa. The above research can provide a goodreference and basis for carbide slag recycling.

颜坤(1988—),男,山东潍坊人,助理研究员,博士。E-mail:kyan@ipe.ac.cn

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YAN Kun,ZHU Ganyu,LI Huiquan,et al.Preparation of active calcium oxide by calcining calcium carbide slag and theeffect of particle size[J].Clean Coal Technology,2023,29(11):133-139.