Impact Of Coal Quality On The Water Quality Characteristics And The Treatment Technology Research Of Coal Slurry

The test analyzed the suspended solid concentration, COD_Cr, zeta potential and pH value of long flame coal and anthracite slurry, the particle size distribution of coal mud particle and the mineral composition of dry slime,calculated the viscosity of coal slurry, and analyzed the reason why coal slurry is difficult to treat; the comparative experiment research on coagulation and sedimentation treatment process was used to treat the coal slurry; finally, the optimum coagulant, flocculant and experimental conditions were determined. At the same time, the effective mechanism which is the foundation to extend the achievement was deeply studied.The research shows that:(1) There exists great differences between suspended solid concentration and COD_Cr because of different coalification degrees and ash content,but the coal slurries present a slight alkalinity and higher zeta potential, and contain a large number of fine slime particles. The coal slurry was thought as a colloid disperse system with negative charges.(2) The main components of coal mud particle is SiO₂ and Al_O3, the structure of coal slime is {(SiO₂)_m·nSiO₃^2-,2(n-x)H⁺}^2x-and{(Al(OH)₃)_m·nAlO₂^-,(n-x)H⁺}^x-.(3) When addition dosage is less, the removal effect of long flame coal and anthracite slurry by Fe³⁺ and Al³⁺ is better than Ca²⁺ and Mg²⁺. The removal efficiency of anionic PAM with molecular weight of 8000 000 and the cationic PAM with 35-45 ion exponent are better than others.(4) This research adopted combined treatment of CaCl₂ and nonionic PAM to treate the long flame slurry.The optimum experimental condition were that: firstly,added 3mL CaCl₂ with concertration of 2%,then stirred for 1min at the speed of 120rpm; Secondly, added 2mL nonionic PAM with concertration of 0.1%, then stirred for 30s at the speed of 120 rpm.(5) This research adopted AlCl₃ and anionic PAM with molecular weight of 8000 000 to treate the anthracite slurry. The optimum experimental condition were that: firstly, added 1mL AlCl₃ with concertration of 2%, then stirred for 30s at the speed of 120 rpm; Secondly,added 1mL anionic PAM with molecular weight of 8000 000 and concertration of 0.1%,then stirred for 30s at the speed of 120 rpm.(6) The analysis of mechanism indicated that Ca²⁺, Al³⁺ and its hydroxyl complex were the most important factors in destroying the stability of colloids. The adsorption bridging action of PAM strengthened coagulation and played an important role in boosting the sediment speed.(7) Finally, the addition dosage of CaCl₂ and PAM were 240g and 8g per cubic metre coal slurry respectively.The reagent treatment cost of long flame coal slurry wasï¿¥0.384 per cubic metre coal slurry. The addition dosage of AlCl₃ and anionic PAM with molecular weight of 8000 000 were 80g and 4g per cubic metre coal slurry.The reagent treatment cost of anthracite slurry wasï¿¥0.248 per cubic metre coal slurry.