乙氧羰基硫代氨基甲酸酯弱碱性条件下优先选铜

Separation of chalcopyrite from pyrite at slightly alkaline conditions using ethoxylcarbonyl thionocarbamate as collector

丁黄药、Z-200和乙氧羰基硫代氨基甲酸酯(ECTC)浮选永平铜矿小型实验和工业实验结果表明,为有效实现铜硫浮选分离,丁黄药要求矿浆pH值不低于12.5,Z-200要求矿浆pH值不低于10.5,而ECTC只要求矿浆pH值为8.5。采用普遍化微扰理论和密度泛函B3PW91/6-31G(D)计算从捕收剂结构与性能的关系对上述实验结果进行了分析。ECTC最高占据分子轨道(HOMO)主要由硫代羰基中硫原子的px和py轨道组成,其能量为-0.217 29(a.u.),给电子能力较弱;最低未占据分子轨道(LUMO)由官能团—O—C(O)—N—C(S)—O—中各原子的pz轨道组成,为共轭π键,接受电子的能力强。ECTC易与表面电子组态为(t2g)6(eg)3Cu(Ⅱ)或t6e4Cu(Ⅰ)的硫化铜矿物形成正配键和反馈键,而难与表面电子组态为(ta2g)3(eag)2Fe(Ⅲ)或(t2g)6Fe(Ⅱ)(碱性条件或弱碱性条件下以Fe(Ⅲ)为主要成分)的硫化铁矿物作用,能在pH 8.5的弱碱性介质中实现优先选铜。UV和FTIR光谱结果进一步证实ECTC捕收剂对铜矿物具有优异的捕收能力,对硫矿物具有好的选择性。

The bench-scale and industrial flotation test results of Jiangxi Copper Corporation Yongping Copper Mine show that the flotation separation of chalcopyrite from pyrite is only achieved above pH 12.5 for butyl xanthate, above pH 10.5 for Z-200 and around pH 8.5 for ethoxylcarbonyl thionocarbamate （ECTC） respectively. The flotation results were analyzed from the structure-activity relationship of collectors by generalized perturbation theory and density functional calculation at B3PW91/6-31G（D） level. ECTC＇s highest occupied molecular orbit （HOMO） is composed of px and py orbits of thiocarbonyl sulfur atom and its orbital eigenvalue is - 0. 217 29 a. u.. ECTC can slightly donate its HOMO electrons. And the lowest unoccupied molecular orbit （LUMO） of ECTC, which is constituted by px orbits of every atoms in the conjugate -O-C（= O）-N-C（=S）-O- group, can easily accept electrons. ECTC collector can be strongly bonded with （t2g）^6 （eg）^3Cu（ Ⅱ ） or t^6e^4 Cu（Ⅰ） on the surface of chalcopyrite through normal covalent bond and back donation covalent bond, but the interaction between ECTC and （t2g）^6Fe（Ⅱ） or（t2g^a）^3（eg^a）^2 Fe（Ⅲ） which is the predominant composition at alkaline conditions in the surface of pyrite is very weak. In the presence of ECTC, the selective flotation of copper sulfide minerals from iron sulfide minerals in Yongping Copper Mine was carried out at slightly alkaline conditions. ECTC is a powerful collector for chalcopyrite and very selective against pyrite, which is further confirmed by the results of UV and FTIR spectra.