Research On The Grinding Properties Of Bauxite With Composite Grinding Aids

The paper takes domestic low and medium grade bauxite as the research object,according to the technical requirements of Bayer process alumina production,aiming at the problems of large energy consumption and steel consumption in grinding production,a series of ball mill experiments were designed,and the cost calculation of the added grinding aids was carried out to develop high-quality and cheap alumina grinding aids.With reference to the process technical parameters of a large-scale Bayer alumina company,a series of grinding experiments were designed with Henan low-grade alumina ore as the raw material to study the effects of mill speed,grinding time,lime-to-ore ratio,and initial grinding concentration on the particle size distribution of the pulp.The optimized experimental parameters of the ball mill experiment are that when the initial concentration of and the mill speed is 100 r / min,the grinding time is 20 min,the lime to ore ratio is 10%,the grinding is 60%.On this basis,five grinding aids AS,SDP,ST,nano anion powder(ANIP)and alkyl glycoside(APG)were screened,and the effects of them and their compound preparations on the particle size distribution,surface tension,viscosity and solid-liquid separation performance of the grinding pulp were investigated separately.1 L ball mill experiment shows that the composite grinding aid ASS compounded by inorganic water-soluble grinding aids AS,SDP,and ST has the best grinding aid effect on bauxite,the qualification rate of grinding is increased by 9.33% compare with the blank group.In the 3L ball milling experiment enlarge on a year-on-year basis,when the feeding ratio of ASS and ANIP is 1%,the grinding pass rate is increased by 3.3% and 3.56% respectively compare with the blank group;the ASS aqueous solution is processed by a self-made magnetizing device for 60 min,and the qualified rate of magnetized ASS(MASS)grinding is increased by 4.95% compare with the blank group,and the slurry solid-liquid separation performance is significantly improved.On the basis of the magnetization grinding experiment,the technological parameters of the 3L ball mill experiment remain unchanged,and the grinding performance of MASS,ANIP,APG and their compound additives on bauxite were investigated respectively.The result shows that the magnetized nano composite grinding aid with the composition of MASS: ANIP: APG = 5: 5: 1,when the dosage ratio is 0.055%,the grinding performance is the best,and the qualification rate of the slurry is 11.05% higher than that of the blank group.The surface tension and viscosity are significantly reduced,and reduce by 17.34% and 81.34%,respectively,and the solid-liquid separation performance was significantly improved over the blank.X-ray diffraction analysis,thermogravimetric analysis,infrared spectroscopy and scanning electron microscopy analysis,extended DLVO theory and sedimentation kinetics are used to discuss the grinding mechanism of grinding aids.The results show that the magnetized nano-composite grinding aid MASS / ANIP / APG has hydrogen and chemical bonds formed on the surface of the bauxite.,and the two interact with each other through chemical adsorption;by extending the DLVO theoretical analysis,it can be seen that the reduction of the surface tension of the slurry can enhance the dispersion of particles and hinder the agglomeration between particles;according to the slurry rheological properties and infrared spectroscopy analysis,it can be seen that the magnetized nano-composite grinding aid can change the morphology of the bauxite,passivate the particles,reduce the frictional resistance,reduce the slurry viscosity and increase the fluidity.It can be seen from the thermogravimetric analysis that the magnetized nano-composite grinding aid has good thermal stability and will not thermally decompose in the alumina grinding system,producing non-condensable gas and affecting normal production.In summary,the addition of magnetized nano-composite grinding aids MASS/ANIP/APG can improve the grinding performance of bauxite,reduce the viscosity and surface tension of the slurry,improve the fluidity and dispersion of the slurry,and significantly improve the solid-liquid separation performance.According to the best investment ratio of 0.055%,the accounting cost is 2.2 yuan/ton,which basically meet the requirements of enterprises on the cost of raw materials.Therefore,the magnetized nano-composite grinding aid MASS/ANIP/APG can be used as a preferred grinding aid for low and medium grade bauxite,providing an effective way for energy saving and consumption reduction in domestic alumina industrial production.