副产硫酸钙室温固相球磨制备氧化钙

Preparation of calcium oxide from by-product calcium sulfate by solid-state ball milling reaction at ambient temperature

以锰尾矿制备硫酸锰过程中副产硫酸钙为原料在室温下与碳酸氢铵进行固相球磨反应,制备出氧化钙的前驱体碳酸钙,然后将其煅烧得到氧化钙.分别考察了物料配比、球磨时间、球料质量比等因素对硫酸钙转化率的影响,采用X射线衍射和化学分析方法对产物进行了分析,并对室温固相球磨反应的机理进行了探讨.在物料配比(摩尔比)为3.5:1、球磨时间为40 min以及球料质量比为5:1时,硫酸钙的转化率可达到99.8%,将固相产物在1000℃热解1 h后所制备的氧化钙纯度为99.2%.室温球磨过程细化了反应物的颗粒尺寸,增加了反应物的接触面积,为引发反应提供了必要的能量,因此提高了化学反应的有效性.

Calcium oxide（CaO） was prepared by directly pyrolyzing the precursor called calcium carbonate （CaCO3）,which was synthesized by solid-state ball milling reaction between NH4HCO3 and CaSO4·2H2O,the byproduct generated during the preparation of MnSO4.The effects of NH4HCO3-to-CaSO4·2H2O molar ratio,milling time,and ball-to-feed mass ratio on the conversion of CaSO4·2H2O were investigated respectively.The product was analyzed by X-ray diffraction and chemical analytical method.The reaction mechanism was also discussed.When the NH4HCO3-to-CaSO4·2H2O molar ratio is 3.5：1,the milling time is 40 min,and the ball-to-feed mass ratio is 5：1,the conversion rate of CaSO4·2H2O reaches 99.8%.Calcium oxide,whose purity is 99.2%,can be prepared by pyrolyzing the precursor at 1000℃for 1 h.The effectiveness of the solid-state reaction is improved by refining the reactant size, increasing the contact area,and providing necessary energy during the ball-milling process at ambient temperature.