Study On The Effect Of Combined Fatty Acids On Separation Of Scheelite From Fluorite And Calcite

Separation of scheelite from calcic gangue minerals is the key problem of scheelite flotation.This thesis reports the role of the combined fatty acids in the separation of scheelite from calcic gangue minerals by flotation experiments of actual ore and single minerals,calculation of solution chemistry and thermodynamics,measurements of contact angle,zeta potential as well as surface tension.The main points of the thesis are indicated as following:Combined fatty acid-based collector shows good effect on the separation of scheelite from calcic gangue minerals.Using combined fatty acid-based collector as flotation collector,water glass as inhibitor to recover scheelite from three kinds of ore,in which the contents of WO₃ are all lower than 0.42%and contents of calcic gangue minerals are various,excellent results with good recovery and grade of WO₃＞65% are obtained.The results of single minerals experiments show that sodium oleate has excellent collecting capability but poor selectivity to scheelite, fluorite and calcite.There is different in collecting capability among fatty acid sodium with various hydrocarbons.Sodium oleate combined with sodium caprylate,or laurate or stearate respectively can enhance the collecting capability to scheelite and fluorite,and sodium oleate combined with either laurate or stearate decrease the collecting ability of reagents to calcite in alkaline condition.Using combined reagent as collector and water glass as inhibitor,the difference of flotability between scheelite and calcic gangue minerals obviously increase,realizing the separation of artificial mixed minerals.Results of orthogonal tests of artificial mixed minerals show interaction effect exists among fatty acid sodium salts;Results of surface contact angle of minerals show that sodium oleate combined with fatty acid sodiums with various hydrocarbons have selectivity in changing the wettability of minerals,and water glass enhances the selectivity:when the dosage of combined reagents reach to 2.47×10^-4mol/L,adding in water glass hydrophobicity of scheelite changes little but hydrophobicity of fluorite and calcite decreases significantly.Results of surface potential tests also show that the selectivity of combined reagents adsorbing on the surface of minerals greatly enhanced after minerals interacting with waterglass.When sodium oleate is used with fatty acid sodiums which have different hydrocarbon,collecting capability of sodium oleate is improved obviously.Results of surface tension tests indicated that the reason may be semi-micelle concentration of the combined reagents being lower than sodium oleate.Results of calculation of solution chemistry and thermodynamics shows the mechanism of sodium oleate reacting with scheelite,fluorite and calcite in neutral and weak alkaline condition is same,which may be the cause that scheelite can not separated from calcic gangue minerals.â–³G⁰ of the reactions of fatty acid sodium which having various hydrocarbon with Ca²⁺ are distinct,which may be the cause that different fatty acid sodium has different collecting capability to minerals.