有机抑制剂SDD与BX在铜活化闪锌矿表面的竞争吸附机制

Competitive adsorption mechanism of organic depressant SDD with BX on copper-activated sphalerite

通过单矿物浮选试验揭示了有机抑制剂SDD对铜活化闪锌矿的抑制情况.在此基础上,采用Zeta电位测试、Versa STAT电化学工作站的局部交流阻抗（LEIS）测试、前线轨道理论计算对SDD和BX（丁基黄药）在铜活化闪锌矿表面的竞争吸附机理进行了研究.浮选试验结果表明：SDD是一种铜锌分离的高效抑制剂,能够有效的抑制闪锌矿,而黄铜矿几乎不受影响;此外,还发现SDD具有用量少且十分敏感的特性,在pH为10,SDD为4.0×10-5mol·L-1的最佳条件下,能够将铜活化闪锌矿的回收率降低至16.59%,而黄铜矿的回收率为81.64%.Zeta电位和局部交流阻抗（LEIS）分析表明：SDD不但能够占据铜活化闪锌矿表面的活化位点,而且其吸附能力强于BX,这极大的降低了BX在铜活化闪锌矿表面的吸附量,从而对铜活化闪锌矿表现出良好的抑制作用.前线轨道理论计算进一步证实SDD与铜活化闪锌矿作用能力强于BX.

The separation of Cu-Zn polymetallic sulfide by flotation has been a difficult and well-researched topic in the field of mineral processing. One of the important reasons why it is difficult to separate Cu and Zn is the presence of a large amount of copper ions in the pulp,which results in the unavoidable activation of sphalerite. The key to solving this difficulty is the development of a high-selectivity depressor for sphalerite. Sodium dimethyl dithiocarbamate（ SDD,C3H6NS2Na） is the lowest homologue of dialkyldithiocarbamate salts,and it has the shortest hydrophobic group（-CH3） in its molecular structure with weak hydrophobicity. In preliminary exploration experiments,it was found that SDD has good selectivity for Cu-Zn sulfide flotation and can achieve better separation performance than conventional depressors. However,the depression mechanism is not very clear. In this work,the depression effect of SDD on copper-activated sphalerite was revealed by conducting a monomineral flotation test. Based on the results of this test,the competitive adsorption mechanism of SDD and BX on the surface of copper-activated sphalerite was further studied by conducting the Zeta potential test,LEIS（ local AC impedance） test of Versa STAT electrochemical workstation,and frontal orbital theory calculation. Theflotation results show that the SDD can effectively act as a depressant in copper-zinc separation. Sphalerite is depressed effectively in the presence of SDD,while chalcopyrite is not depressed. In addition,SDD has the characteristics of small dosage and high sensitivity.Under the optimum conditions with p H of 10 and SDD dosage of 4. 0 × 10-5 mol·L-1,the recovery of copper-activated sphalerite can be reduced to 16. 59%,while the recovery of chalcopyrite is 81. 64%. Analysis of the results of the Zeta potential test and LEIS show that SDD can not only occupy the activation site of copper-activated sphalerite surface but also afford better adsorption capacity than BX,which greatly reduces the adsorption of BX on the surface of sphalerite. As a result,SDD shows a good depression effect for copper-activated sphalerite. The frontier orbital calculations further confirm that SDD is superior to BX in its ability to interact with minerals.