Effect Of Calcium Ion On The Flotation Of Molybdenite And Its Improvement Measures

With the increase of“poor,fine and miscellaneous”molybdenite ore,the grinding fineness increases continuously.In addition,the tailings wastewater is recycled,which causes to increase the number of unavoidable ions in flotation pulp,especially the concentration of Ca²⁺.Besides,the low temperature in the north leads to the decrease of the dispersion of hydrocarbon oil collectors in the winter.Consequently,it is more and more difficult to make full use of molybdenum ore flotation under the conditions of tailings wastewater.Although the effects of ambient temperature,grinding fineness,Ca²⁺in pulp and collector modification on molybdenum separation efficiency have been studied,few people take these factors into account and systematically study their effects on molybdenite flotation.In view of this,the molybdenite pure mineral and the actual ore were used to study the effects of Ca²⁺concentration on the flotation,especially on the flotation of fine molybdenite in low temperature environment.At the same time,a kind of composite hydrocarbon oil collector was prepared by the kerosene and appropriate amount of polycyclic aromatic hydrocarbons,and magnetized modification.The composite hydrocarbon oil collector and magnetized collector were used to improve the molybdenum effect of high calcium water,especially the effect of high calcium water flotation fine molybdenite in low temperature environment.In this paper,the main results of the research work were as follows:The pure mineral flotation test showed that the ambient temperature significantly affected the flotation of molybdenite.The Mo recovery in the environment of 5°C was about 11%lower than that in the 20°C environment.With the increase of Ca²⁺concentration in pulp,the Mo recovery was gradually reduced.When the concentration of Ca²⁺was 800mg/L,the Mo recovery tended to be stable.The negative effect of Ca²⁺on the flotation of fine molybdenite was greater than that of coarse particles.With the increase of p H value,the Mo recovery did not change much in distilled water but was significantly reduced in the high calcium water(contain 800 mg/L Ca²⁺),which indicate that higher alkalinity exist greater negative effect of Ca²⁺on the flotation of molybdenite.The effect of Ca²⁺on the flotation effect of the actual molybdenum ore was similar to that of the pure mineral test.When the concentration of Ca²⁺was800mg/L,the flotation recovery of Mo droped by 3 percentage compared with the tap water.Future increase of Ca²⁺concentration didn't influence the recovery of Mo.The adsorption amount test results showed that the adsorption amount of Ca²⁺on the surface of the fine molybdenite was larger than that of the coarse particles.The chemical analysis of the solution showed that when the p H was less than 12.24,Ca²⁺was not deposit on the surface of the molybdenite in the form of Ca(OH)₂.The XPS test also confirmed that Ca²⁺was present on the edge of the molybdenite particles by Ca Mo O₄,and the relative content of Ca Mo O₄on the surface of the fine molybdenite was 2.15 times that of the coarse particles.These test results indicated that the more adsorption of calcium ions on the molybdenite surface,the greater negative effect on molybdenum flotation,which consistent with the flotation test results.The results of the composite hydrocarbon oil in molybdenum flotation is better than that of kerosene under the condition of both ordinary and high calcium water especially in low temperature environment.The actual ore flotation experiments showed that the Mo recovery was 2.66%higher when composite hydrocarbon oil was magnetized at 20°C and was 1.24%higher when composite hydrocarbon oil was magnetized at 5°C.The result of surface tension,zeta potential,contact angle tests show as below:the surface tension of the composite hydrocarbon oil decreased after magnetization,the absolute value of the zeta potential after adsorption of the magnetized composite hydrocarbon oil on the mineral surface was smaller than that of the adsorbed unmagnetized composite hydrocarbon oil,however,the contact angle of the former was significantly increased.This also confirmed that the magnetized modified composite hydrocarbon oil could effectively improve the flotation of molybdenum.