Study On The Dissolution Characteristic And Microcalorimetry Kinetics Of Scheelite,Fluorite And Calcite

Scheelite and calcium gangue has similar dissolution and surface structure,which makes flotation separation difficult.It is of great significance to find out the dissolution behavior and mineral interaction characteristics of calcium minerals in adjustment agents,which is of great guiding significance to the selection of flotation reagents and the development of new technologies.In this paper,the chemical precipitation method was used to synthesize scheelite,Pb²⁺coated scheelite,fluorite and Pb²⁺coated fluorite,calcite and Pb²⁺coated calcite,the effect of Pb²⁺amplifyied.The dissolution characteristics of minerals in NaOH,Na₂CO₃,Na₂SiO₃ and Na₂CO₃+Na₂SiO₃ regulator solutions and the structure of mineral dissolving in the ultrasonic physical field were studied.The micro thermokinetics of dissolution of minerals in different regulators was explored.The micro thermokinetics of the sodium oleate and salicylic acid on the surface of minerals was found out.The effect of Pb²⁺on the dissolution behavior of minerals and the mechanism of activation were investigated.The results show that:（1）The Ca²⁺dissolved by scheelite,fluorite and calcite decreases with the increase of pH.The WO₄^2-and F^-dissolved by scheelite and fluorite increase with the increase of pH.In Na₂SiO₃ solution,Pb²⁺can promote the dissociation of more Ca²⁺from scheelite and calcite to the solution.The Ca²⁺dissociation effect of Pb²⁺on Scheelite surface is much larger than that of Ca²⁺on the surface of calcite.Pb²⁺promotes the dissolution of F^-of fluorite,but inhibits Ca²⁺dissociation.Under alkaline conditions,the concentration of localized ion F^-on the fluorite surface increases,which is not conducive to the effect of anionic collectors on the mineral surface.The addition of Pb²⁺can enhance the selectivity of the agents and achieve the efficient separation of scheelite,fluorite and calcite.The cavitation effect of ultrasonic can promote the dissolution of minerals.When the ultrasonic power is greater than 600W,the ionic concentration of scheelite,calcite and fluorite can reach the maximum.The cavitation effect of ultrasonic can promote the dissolution of Ca²⁺on the surface of the Pb²⁺coated scheelite,has little influence on the solution of the calcite,and has no obvious effect on the dissolution of Ca²⁺on the surface of the fluorite in Na₂SiO₃ solution.（2）The dissolution of scheelite and calcite in NaOH,Na₂CO₃,Na₂SiO₃ regulator solution is endothermic reaction.The dissolution of fluorite in NaOH and Na₂CO₃ regulator solution is endothermic reaction,while in Na₂SiO₃ solution it is exothermic reaction,indicating that Na₂SiO₃has a strong affinity with fluorite,and the inhibition effect has been achieved.The Pb²⁺will react with the anions in the regulator to release the heat,the heat release increases with the increase of the pH,thus increasing the maximum reaction rate of the mineral dissolution reaction and promoting the dissolution of the minerals.（3）The effects of sodium oleate and salicylic hydroxamic acid on scheelite and Pb²⁺coated scheelite,calcite and Pb²⁺coated calcite are exothermic reactions,while the adsorption of collectors on the fluorite surface becomes endothermic reactions after Na₂SiO₃ inhibition,and the reaction rate is small.Sodium oleate is more easily adsorbed on the surface of fluorite and calcite than salicylic acid,salicylic hydroxamic acid is more easily adsorbed on the surface of scheelite than sodium oleate.After the fluorite is coated by Pb²⁺,the heat effect of the collectors on the fluorite surface transform from the endothermic reaction to the exothermic reaction,and the adsorption rate is increased.The coated Pb²⁺also promoted the adsorption of salicylhydroxamic acid on Scheelite surface.