Study On Calcium Carbide Slag Used As Raw Material For Preparing Calcium Oxide

Carbide slag is a solid waste with Ca?OH?₂ as the main component produced by calcium carbide?CaC₂?.At present,calcium carbide slag is mainly used in construction raw materials,chemical raw materials,environmental protection materials,etc.It's just simple processing or direct use.Consumption is limited and emissions are increasing year by year,and resource utilization of calcium carbide slag is imminent.The use of calcium carbide slag instead of limestone to produce lime can achieve a virtuous cycle of“calcium carbide slag?lime?calcium carbide?calcium carbide slag”,but the biggest problem is that its impurity components cause low purity of lime products and do not meet the quality requirements of lime industrial products,so calcium carbide slag The key to realizing the high value-added resource utilization is to separate and remove the impurity components in the calcium carbide slag at low cost and efficiency.The mineral phase composition and micro-morphology embedding characteristics of calcium carbide slag were studied.The main minerals of calcium carbide slag were Ca?OH?₂ and CaCO₃;Ca?OH?₂ minerals were clustered and stacked in layers,with an average size of 42×217 nm.CaCO₃ has both circular and square shapes,with an average size of 658.7×513 nm,and the main mineral phase grains are all nanoscale.The secondary minerals are quartz,silicon carbide,feldspar,ferrosilicon;a small amount of mineral components are mullite,calcium aluminosilicate,etc.and secondary mineral grains are all micron-sized.The dry-mechanical sieving was used to analyze the particle size distribution characteristics of the chemical composition of calcium carbide slag and the effect of mechanical pulverization on the morphology of Ca?OH?₂ and CaCO₃.The impurity components in the calcium carbide slag raw material are mainly concentrated in the particle size range of-38?m and+315?m,and the CaO content in the particle size range is less than 81%.The CaO content of the remaining particle size is above 85%.After wet mechanical grinding,the coarse-grained calcium aggregates are effectively depolymerized and enriched to the fine fraction.Stabilized calcium carbide slag suspension was prepared by wet ball milling and adding different kinds of surfactants and different dosages.The coagulation of calcium carbide slag after wet grinding is obviously improved.0.2 wt.%Suc+0.5 wt.%HPMC_{100 k}+0.1 wt.%Suc and 0.4 wt.%HPMC_{200 k} wet ball milling time can be prepared for 120 s.Stable calcium carbide slag suspension.The calcium carbide slag suspension is sorted and purified by using a hydrocyclone and adjusting different feed flow rates.The 18²00?m calcium carbide slag suspension is sorted by a cyclone.The CaO content in the overflow calcium material can reach 91%,and the calcium material yield is about 90%.The technical parameters of the cyclone separation are preferred:the inlet flow rate is 4.0 m/s,the viscosity is 2×10⁵ mPa·s hydroxypropyl methylcellulose?HPMC?,and the dispersant content is 0.1 wt.%sucrose and 0.4 wt.%HPMC_{200 k}.Exploring the chemical method to purify the fine-grained carbide particle slag experimental parameters to obtain high-purity calcium material.When the calcium carbide slag is leached,the pH of the solution is suitably in the range of 3 to 4.The leaching solution pH=4,the water bath temperature was 10?,and the CaO content of the calcium product obtained at the stirring rate of 800 r/min was 98.1%.