Study On Bauxite Flotation Desulfurization Behavior Using Modified Imidazole As Collector

With the rapid development of economy,bauxite resources are becoming increasingly scarce in China,which no longer meet the demand for the alumina production.As a result,China has to rely heavily on the imports of bauxite abroad.In China,it has been proved that nearly 560 million tons of high-sulfur bauxite cannot be directly applied in the alumina production due to its high sulfur content.Supposing that the desulfurization problem is solved,it will improve the supply situation of bauxite in our country.Compared with other desulfurization methods,flotation can not only save costs,but also obtain the tailings with higher sulfur content,which is of great value to the comprehensive utilization of the minerals.Therefore,flotation is more suitable for the desulfurization of high-sulfur bauxite.Collector is one of the most important agents in mineral flotation process.However,xanthates with the characteristics of easy deliquescence and unpleasant smell are the main flotation collectors used in high sulfur bauxite flotation desulfurization at present.Therefore,the modified imidazole(DMBI)with stable performance synthesized in the laboratory was used as the collector of flotation desulfurization of high sulfur bauxite in this paper.Moreover,the adsorption mechanism of the agent and mineral was studied.High sulfur bauxite used in this work was from Henan province.The effects of collector dosage,slurry pH,activator dosage,and frother dosage on the flotation desulfurization were investigated.The results showed that the collector dosage of 60 g/t,pulp pH=5 and frother dosage of 240 g/t were the optimal flotation conditions.The bauxite concentrate with sulfur content of 0.58% and alumina recovery of 87.92% was obtained under the optimal conditions.After one roughing and one cleaning flotation process,the bauxite concentrate with sulfur content of 0.27% and alumina recovery of 82.59% was obtained.The sulfur content meets the requirement for the alumina production in the Bayer process(<0.3%).A better desulfurization was obtained using DMBI as collector than that of butyl xanthate reported in the literature.Adsorption test results show that the adsorption capacity decreases with increasing pH as well as temperature.With the increasing DMBI concentration,adsorption capacity increases and reaches the saturated adsorption.The persuo-second-order kinetics equation can well describe the adsorption process.The adsorption of DMBI on pyrite is more consistent with the Freundlich isothermequation at 288.15 K,while the adsorption is more fitted by Langmuir isotherm equation at 298.15 K-318.15 K.Thermodynamic studies display that the adsorption of DMBI on pyrite is nonspontaneous and exothermic.Infrared spectrum,zeta potential and particle size analysis show that DMBI absorbed on the pyrite surface through-SH and –NH groups.The positive charge of pyrite surface increased after the interaction with DMBI.The particle size of pyrite after adsorbing DMBI increased with the increasing solution pH.The XPS analysis indicates that the content of C and N on the pyrite surface changed after intercating with DMBI,which demonstrates that the adsorption of DMBI on pyrite surface belongs to chemical adsorption.