Research And Application Of Static Mixing Optimization Of Coal Slime Water Flocculant In Shangwan Coal Preparation Plant

Coal slime water treatment is an important link in the production process of coal preparation plants.With the strengthening of the country’s environmental protection efforts,coal slime water treatment has becom e the focus of coal preparation plants.Due to the large amount of high-ash fine mud in the slime water,the poor mixing effect of the agent and the slime water during the artificial dosing process,and the instability of the agent addition,which brings great trouble to the slime water treatment of the coal preparation plant.Taking the slime water treatment system of Shangwan Coal Preparation Plant as the research object,this paper analyzedthe properties of slime water,carried out the laboratory flocculation and sedimentation test,studied the flow field of reagent static mixer with different structures based on numerical simulation,designed the static mixer under laboratory conditions,explored the optimal mixing scheme of reagent and slime water,and transformed the slime water dosing system on the production site.The research results have practical guiding significance for the optimization of slime water treatment system in coal preparation plant.The main contents are as follows:(1)The property analysis and flocculation sedimentation test of coal slurry water in Shangwan Coal Preparation Plant were carried out.The results show that the fine particle content of coal slime is high,there are many oxygen-containing functional groups on the surface of coal slime,and the surface of coal slime is negatively charged.The inorganic flocculant polyaluminium chloride(PAC)has little effect on the sedimentation rate and has a great effect on the quality of clarified water.The organic flocculant polyacrylamide(PAM)has a great influence on the sedimentation rate and a small influence on the quality of clarified water.When the dosage of PAC agent is 0.52 Kg per ton of dry slime and the dosage of PAM agent is 0.21 Kg per ton of dry slime,the test slime water has a good sedimentation effect.(2)Numerical simulation of static mixers with three structures of full tube,half tube and shrink down,it is found that for the full tube structure type,because the fluid in the tube is not full,the structural properties of the helical blade tangent to the inner wall of the circular tube causes strong turbulence,and the gas-liquid two-phase coupling is serious.It has an adverse effect on the coal slime flocculation already formed in the slime water fluid,and the resistance along the process is relatively large,which is not conducive to the smooth flow of the slime water fluid into the thickener.For the two geometric models of shrink down and half tube,the gas-liquid two-phase coupling is less than the gas-liquid two-phase coupling of the full tube structure,and the velocity is more uniform,but the velocity nephogram of the half tube structure shows that the half-width spiral blade has the phenomenon of coal slurry water flow falling,it is easy to appear that the flocculation that has been flocculated is broken.Therefore,the shrink down structure with a gap between the spiral blade and the side wall is more suitable for the flocculation of slime water.The reasonable spiral blade shall be a reduced diameter structure with a pitch between 3200 mm and 4000 mm.(3)The chemical flocculation mixing effect of coal slurry water for test is verified by laboratory static mixer.According to the feed pipe parameters of thickener in Shangwan Coal Preparation Plant,it is calculated that the blade size of laboratory static mixer is 200*33.3 mm and the pipe is DN50.The test results show that compared with single point dosing,the flocculation and sedimentation speed of coal slime water by bridge porous dosing is fast.The long length of spiral blade leads to long mixing time,which will destroys flocs and affect the flocculation and sedimentation effect of slime water.The blade with appropriate size is not only simple to manufacture,but also has excellent working effect.It can produce a large velocity gradient in the process of reagent mixing,and the mixing effect is significantly improved.(4)Based on the above research results,the slime water treatment dosing system of the coal preparation plant is further optimized and transformed.After the transformation,the thickener is in good working condition and the reagent system is reasonable.The concentration of the underflow of the concentrator is increased by 65.6 g/L,and the discharge cycle of the pressure filter is shortened by an average of 48s.The consumption of cationic agents is reduced by 6.73%,and the consumption of anionic agents is reduced by 8.81%.After the optimization and transformation of the dosing system,not only the automation degree of the slime water system is improved,but also various technical indexes are significantly improved.