Study On The Effect And Mechanism Of Middling Regrinding On The Flotation Of Chalcopyrite

The application of the middling regrinding process is widespread,which can effectively solve the problems of recovery and separation difficulties faced by middling flotation,and has a prominent effect on improving the comprehensive utilization rate of mineral resources.Although the research on the middling regrinding has been carried out for many years,due to the complex nature of the middling,the many factors affecting flotation,and the large number of physical and chemical changes involved in the regrinding process.The mechanism research has not been systematically deepened,and there are still many gaps and deficiencies,which seriously restrict the development of mineral processing technology.Therefore,it is of great theoretical and practical significance to carry out in-depth research on the mechanism of the influence of middling regrinding on the flotation properties of minerals.Chalcopyrite was used as the research object in this thesis.Scanning electron microscope energy dispersive spectrometer?SEM-EDS?,X-ray photoelectron spectroscopy?XPS?,gas/liquid chromatography mass spectrometry?GC/LC-MS?,other physical,chemical analysis and testing techniques were carried out to study the changes in physical morphology,flotation performance,surface and pulp properties of minerals before and after regrinding.The mechanism of the effect of middling regrinding on the flotation of chalcopyrite was revealed,and the relationship between the ore properties and the regrinding flotation performance was confirmed by artificial mixed ore and actual ore flotation.The main research contents and results are as follows:?1?Through the discussion of the grinding environment and stirring environment after regrinding,including the grinding media type,pH,grinding time,ion concentration,pulp potential,stirring time,collector dosage and other parameters,the general rule of the influence of middling regrinding on the flotation of chalcopyrite was discovered.Combined with the study of mineral surface properties,it reveals the mechanism of the depression of chalcopyrite caused by the low pulp potential and the high surface iron oxide/hydroxide content under mild steel grinding at pH 10.?2?Through the study of ion/reagent adsorption and surface properties,the mechanism of the effects of Cu²⁺,Fe³⁺and Ca²⁺participating in the regrinding on the flotations of chalcopyrite,pyrite and quartz was revealed,perfecting the theoretical study on the flotation effect of ions on middling regrinding.It is found that in alkaline environment,Cu²⁺participating in regrinding formed Cu?OH?₂ to cover chalcopyrite surface,inhibited its flotation,but showed exchanged adsorption and redox reaction on pyrite surface,promoting the conversion of Cu²⁺to Cu⁺.The surface of the pyrite was activated,which increased the difficulty of flotation separation between chalcopyrite and pyrite.Fe³⁺and Ca²⁺participating in regrinding formed hydrophilic Fe?OH?₃ and CaS_xO_y adsorbed on the surface of chalcopyrite and pyrite,inhibited their flotation.The adsorptions of Cu²⁺,Fe³⁺and Ca²⁺on the surface of quartz were relatively low,0.05%,0.02%and 0.15%,respectively,which had little effect on quartz flotation.?3?The mechanism of the effects of butyl xanthate and Z200 on the re-grinding of chalcopyrite in chalcopyrite was discussed.The point of“mechanical activation of collectors”was proposed to provide a theoretical support for the middling regrinding technologies.The study found that when the dosages of butyl xanthate and Z200 were300 g/t and 120 g/t,respectively,the flotation recoveries of the collectors involved in regrinding were 3.59%and 3.73%higher than that of direct stirring,respectively.LC-MS analysis showed that the chemisorption on the surface of chalcopyrite was stronger as butyl xanthate involved in regrinding,more C4H9OCSSCu,?C₄H₉OCSS?₂·H₂O,?C₄H₉OCSS?₂Fe,?C₄H₉OCSS?₂Cu?OH?and?C₄H₉OCSSCu?₂ and other substances were formed,which were beneficial to flotation.GC-MS analysis showed that the physical adsorption on the surface of chalcopyrite was stronger as Z200 involved in regrinding,and the mineral surface was pre-coated to prevent oxidation by forming SO₄^2-,which promoted the flotation of chalcopyrite.?4?The regrindings of excessive oxidation,reagent inhibition and muddy cover chalcopyrite were studied in depth,and the flotation theory of middling regrinding was further improved.It is found that under the optimal regrinding condition,after the over-oxidized chalcopyrite was reground,the surface O content decreased from54.32%to 37.77%,the SO₄^2-content in S decreased from 21.08%to 9.83%.The surface oxide layer was detached,which was beneficial to flotation.After the chalcopyrite inhibited by sodium thioglycolate was reground,the surface contamination C content decreased from 30.81%to 24.58%,and the adsorption capacity of sodium thioglycolate decreased from 0.915 mg/g to 0.335 mg/g.The surface inhibitor desorbed,which was beneficial to flotation.After the chalcopyrite of kaolinite muddy cover was reground,the degree of muddy cover was unchanged,but the surface Fe content was reduced from 27.38%to 25.87%.Some iron oxides/hydroxides were wiped off,which was beneficial to flotation.?5?The effects of regrinding of artificial mixed ore and actual ore on the flotation of chalcopyrite were studied,the intrinsic reasons for the differences between the two was analyzed.The copper recovery of the raw ore from the Wushan copper mine using middling regrinding was 4.04%higher than that of middling sequential return process,which was lower than the artificial mixed ore test index under the same conditions?the copper recovery was increased by 8.01%?.Due to the complex properties of the middling in the Wushan Copper Mine,including the favorable and unfavorable characteristics during regrinding,it was relative difficult to increase the flotation recovery.The copper recovery of the Jinduicheng molybdenum tailings using middling regrinding was 6.08%higher than that of middling sequential return process,which was higher than the artificial mixed ore test index under the same conditions?the copper recovery was increased by 1.18%?.Since the surface inhibited by the reagent was the main feature of the molybdenum tailings flotation middling,slight regrinding could significantly improve its floatability,the increase of the chalcopyrite recovery was more obvious.