Study On The Removal Of Dolomite From Apatite In Direct Flotation Based On Novel And Efficient Dolomite Depressant

China’s phosphorus resources are mainly low-grade phosphate ores,which usually contain various impurities.Generally,it needs to be concentrated by direct-reverse(reverse-direct)flotation process,which have complex flow and high cost.Dolomite is the main Mg O impurity in phosphate ores.Because of the similar surface property and poor selectivity of fatty acid collector,it is difficult to separate dolomite and apatite.Therefore,the development of novel dolomite depressants which can separate apatite and dolomite in direct floatation is of great significance to reduce the flotation process,cut down the cost and strengthen the utilization of low-grade phosphorus ore.In this paper,xanthan gum and iminodisuccinic acid(IDS)were developed as novel dolomite depressants in the direct flotation to separate apatite and dolomite,the effect of depressant on apatite and dolomite was explored and the mechanism was revealed.The main conclusions were as follows:(1)Xanthan gum and IDS exhibited selective depression effect on dolomite,which could efficiently remove dolomite from apatite via direct flotation.Xanthan gum expanded the recovery gap between apatite and dolomite to more than 70%;IDS enlarged the recovery gap between apatite and dolomite to more than 60%.(2)The xanthan gum adsorption capacity and heat of dolomite were much larger than apatite due to the higher density of Ca on dolomite.Xanthan gum was adsorbed on dolomite by means of chelation between-COOH or-OH groups within xanthan gum and Ca sites exposed on dolomite surface.The abundant adsorption of xanthan gum on dolomite impeded sodium oleate adsorption,which resulted in powerful depression effect on dolomite.However,the adsorption capacity of xanthan gum on apatite was much lower than that of dolomite,and it had slight effect on the adsorption of sodium oleate.The interaction between xanthan gum and apatite is weak,and xanthan gum was adsorbed on F sites by the physical adsorption of hydrogen bonding.(3)IDS was more inclined to adsorbed on dolomite surface due to its high affinity toward Mg atoms on dolomite surface.IDS dominantly chelated with Mg sites on dolomite surface though the coordination of COO-groups with Mg sites to form octahedral structure,while only a small portion of IDS was adsorbed on Ca sites.The pre-adsorption of IDS impeded sodium oleate adsorption on dolomite surface,which resulted in powerful depression effect on dolomite.In contrast,the interaction between IDS and apatite was weak and the adsorption capacity of IDS on apatite was much lower than that of dolomite.which has slight effect on the adsorption of sodium oleate.IDS was weakly adsorbed on apatite surface thought hydrogen bonding between F sites on apatite and carboxyl within IDS.