螯合抑制剂BAPTA在菱镁矿与方解石浮选分离中的作用机理

由于菱镁矿和方解石具有相似的晶体结构和化学性质，故通过浮选较难实现二者的有效分离。BAPTA作为一种Ca-选择性螯合剂，被用以改善菱镁矿与方解石的浮选分离。浮选试验结果表明，在油酸钠体系下，BAPTA能选择性地抑制方解石上浮，且在矿浆pH值11.0、BAPTA用量30 mg/L和油酸钠用量100 mg/L的条件下，可较好实现菱镁矿(回收率91.06%)与方解石(回收率7.37%)的浮选分离。利用Zeta电位、FTIR和XPS等检测方法研究了BAPTA的选择抑制机理，结果表明，BAPTA能选择性地与方解石表面的Ca发生反应，吸附并罩盖在方解石表面，阻止油酸钠在方解石表面吸附，消除油酸钠给方解石带来的零电点负移的影响，但BAPTA对菱镁矿表面的Mg作用较小，故对菱镁矿吸附油酸钠的影响较小。 

Mechanism of Chelating Depressant BAPTA in Flotation Separation of Magnesite and Calcite

It is difficult to achieve the effective separation of magnesite from calcite because of their similar chemical and crystal properties. As a Ca selective chelator, BAPTA was used to improve the flotation separation of magnesite and calcite. The flotation test results showed that BAPTA could selectively inhibit the upward flotation of calcite in the sodium oleate system, and the flotation recovery difference between magnesite (recovery: 91.06%) and calcite (recovery: 7.37%) was large at pH 11.0, BAPTA dosage of 30 mg/L and sodium oleate dosage of 100 mg/L, which revealed that the flotation separation of magnesite and calcite could be realized. The selective depression mechanism of BAPTA was studied by Zeta potential, FTIR and XPS. The results indicated that BAPTA could selectively react with Ca on the surface of calcite, adsorb and cover the surface of calcite, prevent the adsorption of sodium oleate onto calcite surface, and eliminate the negative shift of zero electric point caused by sodium oleate on calcite. However, BAPTA had a little influence on Mg on the surface of magnesite, so it has a little effect on the adsorption of sodium oleate on magnesite.