Study On Magnetic Assisted Sedimentation Treatment Of High Turbidity Mineral Wastewater

Due to its special properties,the slime water of high turbidity mineral water is difficult to realize the rapid clarification of the muddy water with high turbidity.The existing clarification technology of slime water can not meet the requirements of coal washing water closed circulation,and it is especially important to solve the problem of high mud and hard settling coal slurry.In order to meet the requirements of clean production and utilization of coal in the new period,the clarification of coal slurry water needs new technical breakthrough.The main reason for the difficulty of flocculation and settlement of the high slime coal slurry is that the electrostatic repulsion between the clay mineral particles is too large,so it is difficult to agglomerate;coal slime flocculation mainly depends on gravity sedimentation,it is difficult to achieve a better settlement by natural settlement when the power of settlement is not insufficient.This paper aimed at the above two questions,first,the magnetic field was used to treat the wastewater with high turbidity,in order to reduce the Zeta potential of the clay particles,and promote its cohesion;simultaneous,In order to accelerate the sedimentation of high turbidity and high sludge sewage,this paper through the magnetic flocculation technology to improve the settling power,and,the magnetic seed material is derived from the magnetic microsphere which is separated from the fly ash.Besides,due to the Zeta potential of the magnetic beads of ash is positive when it under the condition of weak acid,in theory,the clay mineral particles can be directly adsorbed and condensed,so it is also one of the research contents of this thesis.The results show that:1.The pre magnetization can change the Zeta potential of clay mineral particles on the surface of sewage and improve the surface activity,thus increasing the collision probability between particles and increasing the settling effect.Taking into account the factors that influence the effect of pre-magnetization are magnetic field intensity and time of pre-magnetization,and the factors that influence the effect of flocculation and sedimentation are flocculant and coagulant dosage,therefore,select the four factor design and orthogonal test,in order to seek the best combination of factor levels.The orthogonal test results surface:the zeta potential of clay particles was reduced and the surface activity was activated by a 1min pre-magnetic treatment under 214mT magnetic field.Therefore,the coagulation of clay particles and the interaction between clay particles and flocculant were both improved.As a result,fast flocculation was achieved.Compared with traditional flocculation,to achieve the same settlement effect,the sedimentation time,flocculant dosage,and the use of CaCl2 are reduced by 56,25,and 33.3%,respectively.On the other hand,if the same reagent system is used in the pre-magnetization-coagulating method,the tailing slurry volume is reduced by 20.83%and the light transmission is higher than 90%.2?Magnetic flocculation sedimentation can greatly improve the settling velocity of flocs,reduce the hydraulic retention time and shorten the treatment cycle.Due to the factors that influencing the magnitude of magnetic force were the magnetic field intensity and the additive addition of magnetic bead,thus,in this paper,a single factor experiment was carried out to determine the influence law,so as to select the optimal factor level.The single factor test results showed that:Under the same settlement condition,the greater the magnetic field intensity,the faster the settling speed of sewage,however,when the magnetic field strength reached 214mT,if the magnetic field intensity was increased,the settlement effect was not obvious;The settling velocity of sewage is directly proportional to the amount of magnetic beads added,and the more the magnetic beads are added,the faster the deposition rate is,however,when the magnetic flux is more than 2.5G,the increase of sedimentation velocity can be ignored;The effect of particle size on the settling effect was very significant.with the decrease of particle size,the settling velocity was faster and faster,however,when the magnetic beads are crushed,the transmittance of the clarification layer will be reduced,the experimental results show that when the magnetic beads were used to mill 4h,the settling effect was the best.3?Without adding flocculant,under through adjusting the high turbidity mineral wastewater pH,only using fly ash magnetic beads can achieve good settlement effect.Research shows,the Zeta potential of fly ash beads was positive,while the Zeta potential on the surface of clay minerals was negative.When the fly ash is added into the wastewater,the fly ash will be combined with the clay minerals,which will condense into the structure of large particles,so as to increase the gravity and accelerate the sedimentation effect.When adjust wastewater pH by HCl,when the solution appears Isoelectric point,the hydration film between the particles in the solution is weaker it,so it is beneficial to the electrostatic adsorption sedimentation.The test results surface:When adding 3G fly ash to the solution,if the solution pH is adjusted by HCl to between pH=4 and pH=5,the settling velocity of sewage is the fastest.