| Lead complexes of benzohydroxamic acid（Pb–BHA）,as a metal-group collector with metal ions as functional groups,has a good selective advantage and has been applied in many large tungsten mines in China.However,Pb–BHA complex has some problems in practice,such as large dosage of reagents and unstable froth,so it is of great significance to optimize the structure of Pb–BHA complex to improve its collecting ability.In this paper,based on Pb–BHA complex,the effect of multi-ligand assembly on its properties was studied,and the multiple ligands metal-group collector with excellent performance was designed.In this paper,the design and application of multiple ligands metal-group collector are studied.Firstly,the single crystal structure,liquid phase structure and mineral surface adsorption structure of the Pb–BHA complex were analyzed comprehensively,and the corresponding relationship between the molecular structure of the complex and flotation performance was established.Then,the design principles and methods of multiple ligands metal-group collector were constructed,the collector molecular design and flotation performance prediction were carried out to develop new multiple ligands metal-group collectors,their flotation behavior and interaction mechanism were studied,and applied to production practice.The main conclusions of this paper are as follows:（1）The crystal-liquid phase-solid/liquid interface structure of Pb–BHA complex was precisely analyzed.The chemical formula of complex 1（Pb/BHA=1:1）is C56H47N12O28Pb6,and the molecular formula is Pb6L8（NO3）4（HL=BHA）.The adjacent molecules of the complex form a three-dimensional extended polymer with repeated structure through the connection of Pb—O bond with internal and intermolecular hydrogen bonds.The liquid phase structure of complex 1 and its adsorption structure on the mineral surface were Pb4L5（OH）3.The chemical formula of complex 2（Pb/BHA=2:1）is C56H48N12O28Pb6,and the molecular formula is[Pb6L8（NO3）3]NO3.The adjacent complex molecules form polymer structures through Pb—O bonds and intramolecular and intermolecular hydrogen bonds.The liquid phase structure of complex 2 is Pb4L5（OH）3,and its adsorption structure on the mineral surface is Pb4L5（OH）2.The structure-flotation performance analysis of Pb–BHA complex shows that the hydrophobic ability of non-polar group is poor,and the adsorption ability of polar group is insufficient,resulting in insufficient hydrophobicity of mineral surface and poor foaming ability.The introduction of new ligand to form a multiple ligands metal-group with optimized structure is an important way to improve the adsorption ability of polar group and the hydrophobic ability of non-polar group of Pb–BHA complex.（2）The design principles and methods of multiple ligands metal-group collector were constructed and new multiple ligands metal-group collectors were developed.The four new multiple ligands metal-group collectors with the structure of Pb4（L1）5（L2）（OH）2（HL1=BHA,HL2（or Na L2）=OHA、SDS、OL、SPA）were constructed with using octyl hydroxamic acid（OHA）,sodium dodecyl sulfate（SDS）,oleic acid（OL）and styrene phosphonic acid（SPA）as new ligands.The collecting ability and selectivity of four new collectors and Pb–BHA were predicted by calculating the|EHOMO（minerals）-ELUMO（reagents）|,molecular electronegativity xm and distribution coefficient log P.The order of their collecting ability was OL>SPA>SDS>OHA>OH,and the order of selectivity was OH>OHA>SDS>SPA>OL.It can be predicted that the Pb–BHA–SDS and Pb–BHA–OHA multiple ligands metal-group collectors formed by SDS and OHA have excellent collecting ability and selectivity in scheelite,wolframite and cassiterite flotation.（3）The flotation behavior and interaction mechanism of Pb–BHA–SDS and Pb–BHA–OHA multiple ligands collectors were revealed.SDS and OHA at the dosage of 1×10-5 mol/L can significantly improve the collecting ability of Pb–BHA for scheelite flotation,while maintaining good selectivity,indicating that Pb–BHA–SDS and Pb–BHA–OHA have strong selective collecting ability for scheelite flotation.Studies on the liquid phase structure and mineral surface adsorption structure show that the new ligand enters into the Pb–BHA structure through coordination with lead ions,and the liquid phase structure and mineral surface adsorption structure are Pb4（L1）5（L2）（OH）2.The mechanism of Pb–BHA–SDS and Pb–BHA–OHA in scheelite flotation is mainly reflected in three aspects:stronger adsorption strength on mineral surface,enhanced hydrophobicity on mineral surface,and significantly reduced solution surface tension at gas-liquid interface.Compared with Pb–BHA,the multiple ligands metal-group collector has larger colloid particle size,strong adsorption ability and good hydrophobicity.It has stronger adsorption strength at the solid/liquid interface and forms a more hydrophobic mineral surface.The surface tension can be significantly reduced at the gas/liquid interface,forming a more stable foam.Thus,significantly improving the flotation performance of the complex.（4）The application of multiple ligands metal-group collector flotation process at atmospheric temperature.The results of laboratory tests show that both Pb–BHA–SDS and Pb–BHA–OHA can obtain better flotation indexes than Pb–BHA complex,and the dosage of lead nitrate and BHA can be reduced from 800g/t to 500 g/t,and have better foam stability.A tungsten concentrate with WO3grade of 44.13%and recovery of 86.16%was obtained by Pb–BHA–OHA flotation closed-circuit test.The principle flow of"grinding-classification-magnetic separation-sulfide ore flotation-tungsten ore flotation"is adopted in the continuous flotation test.When the grade of raw ore is 0.216%,a tungsten concentrate with WO3 grade of 41.71%and recovery of 84.15%was obtained.151 Figures,56 Tables,186 References... |
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