Study On The Effect Of Inhibiting Clay Mineral Dispersion On The Sedimentation Of Coal Slurry

Previous investigations showed that clay minerals are the major matter that affect the coal separation process.The amount of smectite in coal,although,is very little,its negative influence on the sedimentation and dewaterability of coal slurry is serious.Clay minerals in coal are easy to swell and disintegrate into individual silicate layers on emerged in water,thus deteriorating the sedimentation effect of coal slurry,among those Smectite is the clay that cause hardest sedimentation.Clay inhibition is aimed at improving the effect of sedimentation through inhibiting the dispersion of clay minerals once coal encounter with water.In this paper, smectite was first selected as the object for the study,Ca Cl2 and TMBAC were selected as inhibitors to compare the law of inhibiting and uninhibiting smectite dispersion on the sedimentation of coal slurry,and also analyze changing reasons through particle size,zeta potential and rheological characteristics of the solution,as well as the interaction modes of particles in the solution with the technology of Cryo-SEM.The results showed that compared with uncontrolled condition,Ca²⁺ inhibition could significantly improve the effect of sedimentation of smectite disperse system,that was crystal layer of particle always kept compact F-F structures,the particle kept bigger size under the controlled condition,and the particle zeta potential was lower than those under the uncontrolled condition,particle in water settled freely,solution behaved like a Newtonian fluid.As the concentration of Ca²⁺ getting higher,the effect of sedimentation was enhanced gradually.Under the uncontrolled condition,particle kept bigger size and zeta potential,the crystal layer of particle always kept F-E structures,with the increase of solid concentration,the solution behaved like a non-Newtonian fluid with high concentration of smectite,thus deteriorated the effect of sedimentation.Besides,the lower the concentration and p H of smectite suspension were,the more easily F-F structures particles kept,the better effect of sedimentation was.TMBAC could obviously cause the inhibition of dispersion,the particles always kept bigger size,the zeta potential kept higher,so particle aggregation were better than addition of Ca²⁺,that was the decrease of electric double layer repulsion,so the solution always behaved like a Newtonian fluid while under the uncontrolled condition the solution behaved like a non-Newtonian fluid.Experiments of coal slurry turned out that the addition of Ca²⁺and TMBAC could both improve the sedimentation effect of coal slurry,the particles kept bigger size,the absolute values of particle zeta potential got lower.Under the two dispersal condition,Ca²⁺ inhibition always kept solution behave like a Newtonian fluid.Under the TMBAC uncontrolled condition,the solution behaved like pseudoplastic fluid with yield value and had poor sedimentation performance.So,clay mineral inhibition is effective methods to improve the sedimentation effect of coal slurry,but under the organic controlled condition,dose of inhibitor is the key factor influencing the sedimentation performance.