In the sintering process for the production of alumina technology, the separation of the clinker-dissolving slurry mainly uses natural sedimentation separation technology. However, the separation technology has great limitations. First, the separation time is longer. The second reaction occurs in the red mud and sodium aluminate solution, resulting in the loss of alumina and sodium oxide; and the second is the use of the separation process. The material quality, slurry temperature, and solution concentration are demanding. Once the above process conditions fluctuate, the crude liquid solid content will increase and the separation index will be unstable. Third, the high-concentration, high-solids dissolution slurry will have an increase in solution viscosity. It is difficult to perform liquid-solid separation by natural sedimentation. Therefore, through research and exploration, the search for a rapid separation technology for the clinker-dissolving pulp is an optimization process index, an urgent need to improve the alumina production technology, and has great significance for the development of the aluminum industry. This article discusses the application of centrifugal separation technology in clinker dissolution slurry. 1 Theoretical analysis Centrifugal separation equipment mainly includes cyclones, centrifuges, etc. Now we analyze the separation performance of clinker-dissolving pulp from cyclones, centrifuges and sedimentation tanks: Calculation conditions: Physical parameters of clinker dissolution slurry Particle density : 2890 kg/m3; Medium density: 1235 kg/m3; Solution viscosity; 1.116 x 10-3/m.s. Particle size distribution: See Table 1. The size of the equipment in the calculation is based on the actual equipment size in production. 1.1 In the sedimentation process, the media in the sedimentation tank is not only affected by buoyancy, but also by resistance. Reasons for the resistance are as follows: friction force (viscous resistance) caused by shear stress, and pressure caused by particle shape. Differential resistance (shape resistance), in general, resistance is a function of the Reynolds number and shape. When the Reynolds coefficient Re ≤ 25, the viscosity of the medium plays a major role; when the Reynolds coefficient is 25 Re ≤ 500, both work; when the Reynolds coefficient Re 500, the pressure difference resistance plays a major role. After calculating the particle movement in the sedimentation tank, the Reynolds number is less than 25, it can be seen that the viscous resistance has a greater influence on the sedimentation velocity of the particles than the shape resistance. According to Stokes law, when the Reynolds number of the suspension is less than or equal to 25, that is, when the particles are in the state of laminar flow settlement, the free sedimentation velocity is calculated as follows: For a continuously operating settling tank, the actual settlement velocity is calculated as : v=1.33qm(1-c0/c1)/Ï pulp A(3) Where: A—the settlement area of ​​the settlement tank, m2; qm—the mass flow of the original pulp, kg/s; c0, c1— - The solid concentration of the original slurry and the solid concentration in the sludge (calculated by weight); P-slurry - the original pulp density, kg/m3; 1.33 - - empirical correction factor. Known: Settling tank size Φ10.5 x 4m, Ï pulp = 1310kg/m3 Volume flow rate Q = 200m3/h Settling tank feed solids = 100g/l; Underflow slag L/S = 4.5. It is calculated that: dk=4.5×10-5(m)=45(μm). Regardless of the influence of feeding and discharging on the red mud settlement, when no flocculant is added, a Φ10.5×4m settlement tank can be used. The critical diameter of the separated particles was 45 μm. 1.2 cyclone cyclone is a centrifugal separation device, the particles in the cyclone not only by the influence of gravity, but also by the centrifugal force, the settlement speed faster than the sedimentation tank. According to the formula, the critical particle size of the red mud separated by the cyclone can be calculated: dk=0.701×[μ×g/(Ïs−Ï)×vi]0.5× Do1.5/(Di×He) 0.5 where: μ———viscosity of solution, kg/m·s; Ïs, Ï———density of particles and medium, kg/m3; He———effective height of cyclone, m; vi—feed The average flow rate at the mouth, m/s; Do—the diameter of the overflow port, m; Di—the equivalent diameter of the feed port, m. He=0.74m Do=0.03m Di=0.023m Cyclone treatment amount Q=8.5m3/h After calculation: dk=3.01×10-5(m)=30.1(μm) When the particle size is larger than the critical particle size At the time, it can be completely recovered. When the particle size is smaller than the critical particle size in the turbulent diffusion, theoretical and practical differences will be caused. Usually, the critical particle size is represented by the particle size with a recovery rate of 50%. 1.3 Centrifuge material in the centrifuge by the centrifugal force F = ma = mω2r role, so that the solid particles in the liquid layer to the drum inside displacement, the accumulation of solid particles by the spiral out of the centrifuge, to complete the liquid-solid separation. At the same time, under the action of centrifugal force, the solid particles of the suspension are more likely to agglomerate, so that particles smaller than the critical particle diameter are condensed into large particles. This effect is also called centrifugal condensation effect. Due to the cohesion effect, it promotes the rapid separation of solid and liquid. Centrifugal critical particle size calculation formula: 1.4 Theoretical Analysis of Sedimentation of Red Mud by Sedimentation Tanks, Cyclones, and Centrifuges From the formula for calculating the critical particle size of the red mud separated by the above separation equipment, it can be seen that the greater the amount of feed in the sedimentation tank, the greater the viscosity of the solution. The smaller the liquid density difference, the worse the sedimentation performance and the larger the critical particle size at the time of separation. In a cyclone, the smaller the feed pressure, that is, the smaller the feed rate, the higher the viscosity of the solution and the smaller the liquid-solid density difference, the larger the critical particle size to be separated and the worse the separation effect. In a centrifuge, the smaller the liquid-solid density difference, the higher the slurry temperature (ie, the lower the solution viscosity), the worse the separation effect, and the larger the critical particle size for separation. This is mainly because the critical particle size is determined by the law of Brownian motion and diffusion phenomena in the centrifuge. The diffusion coefficient Dâˆtemperature T, ie, D=KT/3πμd, the average displacement h and diffusion coefficient of particles during time t. The relationship between h2 = Dt, set in time t, when the particles in the sedimentation velocity v, the settlement distance is h = vt, because the particle size is small, the settlement is in the laminar flow region, so: v = d2 · Î”Ï Because ω2·r/18μ (spherical particles), it can be deduced that h=6·K·T/(π·d3·ΔÏ·ω2·r) where: K——— Boltzmann constant, K=1.3805 ×10-6 dyne·cm/K; T———temperature, K; D—particle diameter, cm; ΔÏ—solid-liquid density difference, g/cm3; ω———rotary drum rotation angular velocity, Radian/sec; r———Drum radius, cm. According to the related literature, h=0.293d, it can be deduced that dk=1.734·[T/(ΔÏ·ω2·r)]1/4. From the above formula, it can be seen that when the centrifuge is performing liquid-solid separation, the amount of feed is critical The effect of particle size is not great. 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