Synergistic Mechanism And Flotation Application Of DDTC/3418A On The Jamesonite Surface

The enrichment of lead（Pb）and antimony（Sb）resources is mainly achieved by the flotation of sulfide minerals.However,this situation is facing increasingly serious challenges due to the depletion of easily separated minerals,stricter environmental protection policies and so on.Industrial practice shows that the combination of different collectors can effectively exert the advantages of various collectors to improve the flotation performance.Jamesonite is an important strategic lead-antimony sulfide mineral and has a rather complex crystal structure including three different metallic elements,i.e.,Pb,Sb and Fe.In this paper,the synergistic mechanism and flotation application of DDTC and 3418A on the jamesonite surface was studied with density functional theory（DFT）and coordination chemistry principle.The main results are as follows:1)Jamesonite was a typical semiconductor sulfide mineral with a narrow band gap,and its crystal structure conformed to the principle of high packing theory.Each Pb or Fe atom in the jamesonite bulk was bound to 6 S atoms to form octahedral coordination,which was like that of galena or pyrite but more distorted.There were three kinds of Sb atoms,including two types of three-coordinated Sb S₃ structures and a type of four-coordinated Sb S₄ structure.These Sb S₃ modes were more similar to those found in the stibnite crystal,while the four-coordination was unique to the jamesonite structure.The（001）surface of jamesonite contained two different subsurfaces,that was Pb-termination and Sb-termination.There were two types of Pb atoms and one type of Fe atoms in the Pb-termination,and the coordination number of these atoms was reduced from the 6-coordination of the bulk to the 4-coordination structure.These Pb atoms were sparsely distributed symmetrically around a central Fe atom;besides,these Fe atoms became quite stable due to the significantly enhanced covalent effect of Fe—S bonds,while the Pb atoms were rather active due to the weakened of Pb—S bonds.Sb atoms in the outer layer of the Sb-termination were distributed in a concentrated manner,and the distance between adjacent Sb was from0.35 nm to 0.42 nm.These Sb and S atoms of the surface have been reconstructed and their structures were similar to those of stibnite crystals.2)Single mineral flotation showed that mixed collectors had good selectivity of jamesonite,especially the combination of DDTC and 3418A.Further research showed that the best combination was DDTC and 3418A in a molar ratio of 2:1,and medium or weakly acidic environment was the ideal p H.In addition,the results also showed that the mixed collector of DDTC/3418A had a faster response time than that of the DDTC.Open-circuit test with real ore indicated that 3418/DDTC mixed collector could effectively improve the flotation performance of refractory Pb-Sb-Zb ore.3)At the p H range of 5～9,the adsorption of DDTC,3418A,and mixed collector（DDTC:3418A=2:1）on the jamesonite surface followed a pseudo-second-order kinetic model,and the order was:DDTC>mixed collector>3418A.FTIR and XPS analysis indicated that both DDTC and3418A had chemical adsorption on the surface of jamesonite,and these compositions could also be detected on the mixed collector treated jamesonite surface.SEM-EDS analysis confirmed that DDTC could be adsorbed on the surface of jamesonite in the form of chemical adsorption,however the interaction was far less than that of 3418A.In addition,significant synergetic mechanism was found in the adsorption of DDTC/3418A mixture on the jamesonite surface,in which the 3418A provided more chemical adsorption.4)Both DDTC and 3418A molecules were coordinated with jamesonite in the form of bidentate ligands.There were three similar adsorption forms of DDTC and 3418A molecule on the Pb-termination,that was Pb_Ⅰ-Pb_Ⅱhollow adsorption,Pb_Ⅰ-Fe bridge adsorption,and Pb_Ⅰ-Pb_Ⅱbridge adsorption,in which the Pb_Ⅰ-Pb_Ⅱbridge adsorption was the most stable model,followed by Pb_Ⅰ-Pb_Ⅱhollow adsorption.In addition,the adsorption of 3418A was stronger than that of DDTC.There were five bidentate adsorption modes on Sb-termination for DDTC or 3418A molecule,that was Sb_Ⅰ-Sb_Ⅱbridge adsorption,Sb_Ⅱ-Sb_Ⅲbridge adsorption,Sb_Ⅰ-Sb_Ⅲhollow adsorption,Sb_Ⅰ-Sb_Ⅱhollow adsorption,and Sb_Ⅱ-Sb_Ⅱhollow adsorption.However,the two bridge adsorptions were more stable than these of bridge adsorptions,which mainly attributed to the stepped distribution of atoms on the surface,meanwhile,the adsorption energy for the 3418A was stronger than that of DDTC.As a typical narrow band gap semiconductor mineral,the surface charge distribution of jamesonite is transferable.The pre-adsorbed collector would affect the charge distribution of the adjacent atoms and inhibit their interaction with subsequent collector molecules.Meanwhile,the subsequent adsorption would also weaken the binding effect of the previously adsorbed molecules,which was more obvious in the adsorption of 3418A.5)The intermolecular N...H hydrogen bonds in the DDTC system maked its micelle bigger and denser,however,the high cohesion also led to low diffusion efficiency and unstable adsorption on the jamesonite surface.Intermolecular hydrogen bonds could not be formed in the 3418A system.Therefore,micelles of the 3418A system were small and loose,which provided conditions for effective adsorption on the jamesonite surface,but poor foaming ability as well as unstable foam were also inevitable problems.Therefore,the combination of DDTC and 3418A could introduce a certain numbers of H...N hydrogen bonds,while keeping the micelles loose,which could achieve efficient adsorption and foam stability on the jamesonite surface.6)Batch,pilot,and industrial flotation tests with Dachang 105#refractory Pb-Sb-Zn polymetallic ore showed that the DDTC/3418A mixed collector could significantly improve the Pb-Sb flotation.Pilot tests showed that the Pb-Sb grade and Pb and Sb recoveries in the DDTC/3418A mixed collector flotation were 6.24%and 7.28%,6.04%higher than that of DDA flotation,and the Zn content was decreased by 4.42%.Industrial flotation showed that many problems existing in the old DDA flotation such as thick pulp and bad flotation of coarse Pb-Sb minerals have been greatly improved,and the content of impurity zinc in Pb-Sb concentrate was significantly reduced;statistics from July 2020 to June 2021 indicated that the cost of flotation reagents has been reduced by 15.05%,and the overall revenue was increased by 7.89 million yuan.