Leaching characteristics of impurity ions with Ca2+in calcium carbide slag during different acid leaching processes
The industrial processes of PVC,ethylene,and so on produced a significant amount of calcium carbide slag,leading to severe environmental issues and resource wastage.Acid leaching is a pre-treatment technique employed for extracting calcium from calcium carbide slag to produce high-value calcium-based chemicals like nano-calcium carbonate.However,impurity ions present in the slag are inevitably leached during this process,adversely affecting the purity of Ca2+.In the present study,HC1 and NH4C1 leaching systems were compared and the effect of various leaching conditions(molar ratio,temperature,agitation rate and time)on the leaching efficiencies of calcium and impurity ions(Al3+,Mg2+and Fe3+)was investigated.One-way experiments,orthogonal experiments,and analysis using different characteristics were conducted.The findings revealed that the conversion rate of Ca2+was higher in the HC1 system compared to the NH4C1 system.Amongst different leaching conditions studied here,molar ratio had the most significant influence on Ca2+conversion rate followed by time＞temperature＞stirring rate.Leaching agent dosage emerged as the most influential factor affecting ion leaching in both systems while other factors exhibited small or even negligible effects.The HCl leaching system can leach Al3+,Mg2+and Fe3+,while the NH4C1 system can only leach Al3+and Mg2+,and its concentration is much lower than the HC1 system.
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