Synthesis,Flotation Characteristics And Mechanism Of Novel Copper-Lead Sulfide Mineral Collectors

Copper-lead-zinc metal sulphide ores are important non-ferrous metal mineral resources in China.Flotation is the most common enrichment method for the recovery of sulphide ores,while collectors play a crucial role in the mineral flotation separation.In this paper,the collectors of novel alkyl ether dithiophosphate and morpholine dithiocarbamate were designed and synthesized,and their flotation collecting ability and separation selectivity for different sulphide minerals were investigated.The interaction mechanism between collectors and minerals was explored by various surface analysis and testing methods.Finally,the novel collectors were applied to the flotation recovery of copper-lead minerals from actual copper-lead-zinc ores.Three alkyl ether ammonium dithiophosphates,including di（2-propoxyethyl）ammoniumdithiophosphate（PREAT）,di（2-butoxyethyl）ammonium dithiophosphate（BUEAT）and di（2-phenoxyethyl）ammonium dithiophosphate（PHEAT）,were prepared by direct reaction of ether alcohol,phosphorus pentasulfide and ammonia.Three morpholine dithiocarbamates,including morpholine dithiocarbamate propylene ester（MDPE）,morpholine dithiocarbamate hydroxyethyl ester（MDHE）and morpholine dithiocarbamate benzyl ester（MDBE）,were synthesized by the reaction of morpholine,carbon disulfide,sodium hydroxide and halogenated compounds in water.The target products were confirmed by UV spectroscopy,FTIR,MS and NMR spectroscopy after purification.The flotation separation behaviors of alkyl ether dithiophosphates for galena and sphalerite,chalcopyrite and pyrite were systematically investigated.The flotation results showed that in the appropriate concentration and p H range,compared with the traditional ammonium dibutyl dithiophosphate（ADD）,the flotation separation of galena and sphalerite by BUEAT was more efficient,and the collecting ability of chalcopyrite and the selectivity for pyrite by BUEAT were better than ADD.UV spectra analysis showed that BUEAT could selectively interact with Pb²⁺,but not with Zn²⁺.Zeta potential results indicated that the adsorption of BUEAT onto the surface of galena made the potentials significantly negative shift,but had no obvious effect on sphalerite.Wettability results revealed that BUEAT could significantly enhance the hydrophobicity of chalcopyrite and galena surfaces,but had little effect on the hydrophobicity of pyrite and sphalerite surfaces.FTIR and XPS results confirmed that BUEAT chemically bonded to metal（Cu or Pb）sites on the surface of chalcopyrite or galena through P=S and P-S groups.The results of surface tension pointed out that the introduction of C-O-C groups in the molecule was beneficial to reduce the surface tension of dithiophosphates in aqueous solutions,exhibiting higher surface activity and stronger hydrophobicity than traditional ADD,which was in agreement with quantum chemical calculations of BUEAT and ADD collectors.The flotation separation behaviors of morpholine dithiocarbamates toward sulphide minerals（chalcopyrite,galena,sphalerite and pyrite）were systematically investigated and compared with traditional Z-200 and Ester-105.The results of single mineral flotation showed that MDPE,Z-200 and Ester-105 exhibited comparable collecting ability for chalcopyrite,while the flotation selectivity of MDPE for galena was significantly better than that of Z-200,slightly worse than that of Ester-105,and the flotation selectivity for sphalerite and pyrite was significantly better than that of Z-200 and Ester-105,indicating that the introduction of morpholine group could significantly improve the flotation selectivity of MDPE for galena,sphalerite and pyrite without affecting the collecting ability for chalcopyrite.UV spectra suggested that MDPE could selectively react with Cu⁺or Cu²⁺,rather than with Fe²⁺,Fe³⁺or Zn²⁺.The results of wettability and adsorption amounts indicated that MDPE could significantly enhance the hydrophobicity of chalcopyrite surface and had obvious adsorption behaviors on the chalcopyrite surface.The changes of adsorption capacity on chalcopyrite surface with p H and dosage were basically consistent with the changes of single mineral flotation performance.The results of FTIR and XPS demonstrated that MDPE formed Cu-S bonds on the surface of chalcopyrite through the S atoms of C=S group in the molecules,and chemically adsorbed on the surface of chalcopyrite.The results of surface tension showed that MDPE was more efficient in reducing the surface tensions in aqueous solutions than traditional Z-200 and Ester-105,displaying higher surface activity,which was in accordance with the quantum chemical calculations of collectors.Based on the flotation characteristics of novel MDPE and BUEAT collectors on copper-lead-zinc-iron sulphide minerals,they were applied to the recovery of copper-lead minerals from actual copper-lead-zinc sulphide ores in China.For a high-grade copper-lead-zinc sulphide ore in Inner Mongolia,the process of“preferential flotation of copper,copper-lead mixed flotation,zinc separation from copper-lead tailings”was adopted.In the closed-circuit experiment,copper concentrates with copper grade of 18.21%and copper recovery of 70.04%,copper-lead mixed concentrates with copper grade of 5.42%,copper recovery of23.20%and lead grade of 42.18%,lead recovery of 82.71%could be obtained.The total recovery of copper in the copper concentrates and the copper-lead mixed concentrates could reach 93.24%under the new reagent system.For a low-grade copper-lead-zinc sulphide ore in Hunan,the copper-lead-zinc preferential flotation process was adopted,combined with the novel collectors MDPE and BUEAT,the copper concentrates with copper grade of 1.45%and copper recovery of 22.79%,the copper-bearing lead concentrates with copper grade of 2.74%,copper recovery of 49.50%,and lead grade of 53.86%,lead recovery of 83.85%were finally obtained by the closed-circuit test of the on-site process samples.The valuable metals such as copper,lead and zinc in the ores were comprehensively recovered to the maximum extent.