| High turbidity mineral wastewater mainly refers to mining and washing wastewater containing a large number of fine-grained,easily muddy,difficult-to-sediment mineral particles,of which coal slurry water is a comnon high-turbidity mineral wastewater.Coal slurry water is the industrial wastewater generated by wet coal washing in coal preparation plant.Its settlement and clarification is the key link in the coal preparation process.In-depth study of clay mineral wastewater such as slime water,exploring new processes for clarification and treatment,is of great significance for the green and efficient treatment of high turbidity mineral wastewater.The fundamental reason for the difficulty in sedimentation of high turbidity coal slurry water is that the slime particles in the slime water are fine and the sedimentation power is insufficient.On the one hand,the negatively charged colloidal particles on the surface of the clay mineral particles increase the dispersibility and stability of the particles,which makes it difficult for the slime particles to aggregate and grow.Moreover,the higher the absolute value of the zeta potential on the surface of the ore particles,the greater the electrostatic repulsion between the colloidal particles and the better the stability between the colloidal particles.On the other hand,the hydration film on the surface of the ore particles increases the hydration repulsion between the particles,prevents the agglomeration between the particles,and reduces the sedimentation velocity of the particles and agglomerates.In view of the above problems,this paper introduces the magnetic treatment method into the sedimentation process of coal slurry water to improve the surface properties and sedimentation dynamics of the ore particles.Clay is the main impurity component in coal slurry water.It is a solution characteristic of simulated slime water.Kaolin and bentonite are used as raw materials to prepare high turbidity clay sewage.The pretreatment experiments of water(solution)and clay sewage were carried out by using strong magnetic field,and the magnetic flocculation experiment of clay soil was carried out by using magnetic particles of fly ash as magnetic species.The magnetization pair was revealed by studying the influence of premagnetization on the sediment tailing mud height and supernatant transmittance,the process parameters of magnetic flocculation,and the influence of strong magnetic field on the crystal-like structure of water and the surface characteristics of clay ore.The influence law of physical and chemical properties of mineral wastewater and the mechanism of magnetic field assisted sedimentation of high turbidity mineral wastewater are discussed.The principle of magnetic flocculation sedimentation is discussed,which provides theoretical support for green high-efficiency clarification of high muddy sewage.The research shows that:1.For the 250 ml mass fraction of kaolin solution used in the experiment,the optimum amount of coagulant is 6ml5 and the best flocculant is 4 mL.The effect of coagulation and sedimentation of clay sewage after pre-magnetization is obviously better than that of ordinary coagulation sedimentation.Under the same dosage of the same agent,the height of the tailings after co-coagulation and coagulation was reduced by 7%,which reduced the cost of the tailings,and the light transmittance increased by 11.7%.2.The water,salt solution and clay solution were taken as the research object.The mechanism of the magnetic field on the clay wastewater was studied by taking the conductivity,pH value,light transmittance,zeta potential and crystallization of the compound as the control indexes.Studies have shown that the effect of magnetic fields on aqueous solutions is divided into two mechanisms of action.The first is the "ion mechanism".The magnetic field works on water molecules and ions dissolved in the solution,which affects the changes in the physicochemical properties of the aqueous solution.Through the magnetization of the magnetic field,the pH and conductivity of tap water and deionized water tend to increase,and the change of tap water is greater than that of deionized water;the pH and conductivity of the salt solution also increase,and the change of salt solution More than the change of the aqueous solution,the light transmittance of the salt solution also has a significant change.The magnetic action also affects the nucleation process of CaCO3 precipitation.Under the action of magnetic field,CaCO3 precipitates to form aragonite precipitate.The second is the"surface mechanism" of the magnetic field.The magnetic field can affect the surface charge of the particles.The magnetic field acts to reduce the zeta potential of the surface of the granular minerals in the clay sewage,and reduce the electrostatic repulsion between the clay particles,thereby reducing the hydration film on the surface of the particles.These two mechanisms act at the same time,so the sedimentation effect of the high turbidity sewage under the action of the magnetic field is obviously improved.3.Through the magnetic flocculation,the sedimentation power of the clay floe is greatly improved,and the sedimentation speed and clarification effect of the clay sewage are significantly improved.The proportion of particle size<2.30 ?m in kaolin particles is 50%,and the proportion of particle size<4 ?m is 75%.Due to the high content of fine particles,the degree of muddyness after dissolving in water is high,and kaolin sewage is difficult.Quickly and naturally settle by gravity.The dosage of PAM solution with a mass fraction of 0.1%is 0.035 g/L,the amount of CaCl2 solution of lmol/L is 0.003 mol/L,the magnetic field strength is 196 mT,the diameter of magnetic species is 10.66 urn,and the amount of magnetic species is 2 g.Under the condition,the magnetic flocculation sedimentation effect of kaolin sewage is the best,the magnetic flocculation sedimentation rate is 2.675 cm/g,the tail mud height is stable at about 3 cm,and the supernatant liquid transmittance can reach 93%. |
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