| Molybdenum is a very important rare mineral resources,which exists largely in oxidized ores and sulphide ores in nature.About 99%of metallic molybdenum comes from molybdenite.The talcose molybdenum resources are abundant but the resources utilization is low,because the talc is naturally hydrophobic and the floatability of talc is similar with molybdenite,which lead to difficult separation by flotation.Talc is easy entry into concentrate in flotation which can cause the content of MgO overhigh,therefore the molybdenum concentrate grade can not meet the industrial requirements.Thus the utilization level of talcose molybdenum resources has been restricted greatly.Surface properties and flotation performance of molybdenite and talc were done in paper firstly,flotation method and technolgy were presented based on control floatability difference.The effect mechanism of talc floatability on molybdenite flotation behavior,the methods and technolgies of adjusting and control floatability difference,the selectivity depression mechanism of agents on minerals in flotation have been systematically studied in this thesis.Based on above research results,the theoretical model and control technolgy of flotation on talcose molybdenite have been established.At last,flotation technolgy to process practical ore was investigated.1.Minerals surface properties and interaction effect mechanism of flotation behaviorCrystal structure,zeta potential of molybdenite and talc,surface wettability,and interaction between H2O molecule and minerals surfaces were studied.The results showed that molybdenite and talc were layered minerals which exhibited similar surface wettability and H2O molecule had hardly effect with molybdenite or talc.The interaction and flotation behavior were studied by AFM,DLVO theoretical calculation and flotation experiments.The reason why talc interferes with the flotation molybdenite has been revealed.The agglomeration between molybenite and talc was caused easily in neutral or acidity solution,and it was dispersing between molybenite and talc particles in alkaline solution.The flotation results showed that good floatability of talc was the key factor causing a low grade of concentrate in alkaline solution.Thus,it is the key factor to enlarge floatability difference between molybdenite and talc.2.The effects of metal ions on flotation behavior of molybdenite and talcMetal ions Ca2+,Mg2+,Cu2+,Fe2+,Ni2+,Pb2+,Fe3+,Al3+ effects on flotation behavior,the function form of meal ions on mineral surface and interaction mechanism between them were investigated by solution chemistry calculation,zeta potential test,real-time detection of particle size distribution and calculation of electrostatic interaction energy.The presence of metal ions has significant effects on flotation behaviors of molybdenite and talc.Solution chemistry calculation verified that the existing forms of metal ions varied in different pH values.The zeta potential of mineral surface decreased by the adsorption of metal hydroxyl complex,leading to the decrease of electrostatic repulsion force between particles.Therefore,the agglomeration of mineral particles increased,giving a higher mineral recovery.The metal hydroxide precipitation was generated on mineral surfaces by increasing the pH of solution.The metal hydroxide precipitation having a high polarity was easy to interact with moisture molecule,decreasing the floatability of minerals.When the pH value above the PZC of hydroxide precipitation,the zeta potential of hydroxide precipitation transferred from positive to negative.Meanwhile,electrostatic repulsion forces between hydroxide precipitation and mineral particles increased,leading to desorption of hydroxide precipitation and increasing of flotation recovery.The agglomeration of mineral particles and non-selective inhibition caused by metal ions did harms to separation of molybdenite and talc.Sodium hexametaphosphate can chelate with multivalent metal ions,decreasing or eliminating bad effects of metal ions on flotation.3.The effects of depressants and sequence of adding agents on flotation behavior of molybdenite or talcInteraction mechanisms between mineral surfaces and depressant and collector were investigated by FT-IR,adsorption test and zeta potential measurement.The interaction order of flotation reagent on effects of flotation differences of molybdenite and talc was studied,providing the basis for the establishment of flotation separation process.The organic high-molecular polymers,glucan and yeast starch are effective inhibitor of molybdenite,which have little depression effects on talc.Thus,talc is firstly removed by flotation.Xanthate is effective collector of molybdenite,which can float the depressed molybdenite.Guar gum are effective inhibitor of talc.However,molybdenite are also suppressed by guar gum.The flotation differences of molybdenite and talc can be increased by regulating and controlling the adding sequence.Xanthate had a selective collecting effect on molybdenite,meanwhile,did not impact with talc.Therefore,in direct flotation,xanthate was added preferentially,depressing and decreasing inhibition of guar gum on molybdenite surface,increasing selective depression of reagents on molybdenite and talc.4.Flotation technolgy of talcose molybdenite oreA novel flotation technolgy which was removal talc and depressing molybdenite by reverse flotation then gathering molybdenite and depressing talc by direct flotation was developed for talcose molybdenite ore based on the theory research.Flotation separation experiments of talcose molybdenite raw ore with 0.14%molybdenum grade were carried out by flotation column.The flotation process was first reverse flotation and second direct flotation.The talc was removed by roughing and cleaning.Then molybdenite ore was recovered by one rougher,twice scavengings and four cleanings.Finally,the qualified molybdenite concentrate with the grade of 46.82%and recovery of 83.28%was obtained,which provide technical supports for processing talcose molybdenite ore in our country. |
PDF Full Text Request