Effect Of Pulp Rheology On Desulfurization Of Bauxite Flotation

In recent years,with the increase of aluminum demand and the decrease of high-quality bauxite resources,the development and utilization of high-sulfur bauxite resources have been paid more attention.In order to improve the utilization of high-sulfur bauxite resources and ensure the sustainable development of bauxite industry in China,the research on desulfurization methods of high-sulfur bauxite should be strengthened continuously.Flotation is an effective method for processing high-sulfur bauxite,High quality bauxite can be obtained by flotation treatment,which improves the comprehensive utilization rate of high sulfur bauxite ore.At present,the research on bauxite in China is mainly focused on the removal of silicon impurities in bauxite,so as to improve the alumina silica ratio of bauxite.The efficient and environmentally friendly removal of sulfur impurities in high sulfur bauxite is an important and difficult point in bauxite research.At present,there are many researches on process mineralogy,agent and flotation process of high sulfur bauxite,but less research on pulp hydrodynamics in flotation machinery.Slurry rheology is a subject to study the flow and deformation properties of pulp under the action of external shear stress.Due to the relatively high content of various solid phase,the slurry has a relatively small change in the rheological characteristics of the slurry.In the actual flotation process.The properties of ore,pulp stirring,concentration,particle size,reagent,pH value,pulp concentration and other factors in the flotation process directly affect the flotation effect.By studying the relationship between pulp rheology and flotation effect,the method to improve pulp rheology and then improve flotation effect is found,which provides guidance for flotation desulfurization of high sulfur bauxite and realizes the optimization of process indexes.The effects of four fine minerals,which were fine diaspore?FDIA?,kaolinite,illite,and pyrophyllite(D₅₀ is about 4.55?m,D₈₀ is about 10.78?m),on the pulp rheology of the diaspore and pyrite mixed ores(D₅₀ is about 120.53?m,D₈₀ is about 187.36?m)and the recovery of pyrite were investigated through flotation tests,pulp rheology measurements,and sedimentation tests.It was found that fine minerals could change the pulp rheology and affect the pyrite recovery.The apparent viscosity of the mixed ores slurry increased with the addition of FDIA,kaolinite,and illite and the pyrite recovery decreased in varying degrees.When the addition was 15 wt.%,the recovery of pyrite decreased from 92.3%to 60.8%,81.4%,and 84.7%,respectively.The addition of pyrophyllite had a significant deteriorating effect on flotation.When the addition of pyrophyllite was 5 wt.%,the pyrite recovery was reduced to 49.2%,and when the addition was further increased to 15 wt.%,the pyrite recovery reduced to 28.5%.However,the effect of pyrophyllite addition on the pulp rheology of the mixed ore was not remarkable.Pyrophyllite affected pyrite recovery not only by affecting the rheological behavior of the pulp,but also because pyrophyllite was adsorbed on the surface of pyrite and diaspore,producing hetero-aggregation,which made it difficult for the pyrite particles to collide with the bubbles effectively.This was the main reason for the reduction of pyrite recovery.the order in which the reduction of pyrite recovery was affected by the dosage of fine minerals was pyrophyllite>FDIA>kaolinite>illite.The effects of sodium hexametaphosphate on flotation kinetics and slurry rheology of pyrite and diaspore with different particle sizes were studied by flotation kinetics test and slurry rheology test.It is found that sodium hexametaphosphate can effectively reduce the apparent viscosity of diaspore and pyrite pulp in the whole particle size range,and can effectively improve the flotation speed of the two minerals.The pulp viscosity has a good correlation with the flotation speed.The recovery rate of pyrite in all particle sizes is about 95%.However,diaspore can only float up with the size of-0.045+0.013mm and-0.013mm.The results show that the surface property is the decisive factor of flotation speed,while the rheological property of pulp is the secondary factor.At the same particle size,the apparent viscosity of diaspore slurry is much higher than that of pyrite.The sphericity of diaspore is higher than that of pyrite by SEM,Generally,mineral particles with high sphericity have lower apparent viscosity in pulp.But in this study,on the contrary,diaspore particles with higher sphericity have higher apparent viscosity.It shows that the particle morphology is not the main reason for the difference of rheological properties between diaspore and pyrite slurry.Consequently,In the flotation desulfurization of bauxite which disseminated grain size is coarse,adding appropriate amount of sodium hexametaphosphate can effectively improve the pulp rheology,then increase the flotation speed and reduce the production cost.In the flotation desulfurization of bauxite which disseminated grain size is relatively fine,when sodium hexametaphosphate is used,appropriate diaspore inhibitor should be added to reduce the adverse effect of diaspore flotation.Through the actual ore flotation test and slurry rheology analysis,the effects of grinding fineness,reagent system and slurry concentration on the actual ore slurry rheology and flotation effect were studied.It is found that the grinding fineness and slurry concentration will change the slurry rheological properties.When the grinding time is longer,the viscosity of the slurry increases and the recovery rate of sulfur in the sulfur concentrate has been increasing,but when the proportion of-0.075mm reaches 98.1%,although the viscosity of the slurry continues to increase However,the sulfur recovery rate has decreased,which shows that the sulfur recovery rate is not absolutely affected by the slurry viscosity.It may be that grinding time has a significant effect on the dissociation of minerals,thus affecting the recovery of sulfur.When the pulp concentration increases,the pulp viscosity increases gradually,but the flotation effect will become worse.It shows that when the pulp concentration increases,there is a correlation between pulp rheology and flotation effect.In addition,it is found that in a certain range of dosage,the dosage of flotation agent will have an impact on the flotation effect,but will not have a significant impact on the rheology of pulp.in this time,there is no inevitable relationship between pulp rheology and flotation effect.The test results of the whole process of high-sulfur bauxite show that the flotation process of one rough selection,one selection and one sweep can obtain aluminum concentrate with a recovery of 89.23%and a grade of 67.13%.At this time,the sulfur content in the aluminum concentrate was reduced to 0.26%,which met the sulfur content requirement of alumina produced by the Bayer process.