Preparation And Properties Of Starch Graft Copolymer Coal Water Slurry Dispersant

Coal water slurry is briefly introduced through the structure type of coal water slurry and coal water slurry performance requirements; the dispersing mechanism of coal water slurry is expounded; the research status of coal water slurry dispersant is described through the classification of coal water slurry dispersant. Currently, due to the increasing energy problem and environmental pollution problems, coal-water slurry as a kind of clean coal combustion technology are highly valued by insiders; Coal water slurry dispersant is one of the most important additive during the preparation of coal water slurry; it is also to the development direction of green environmental protection, biodegradable, nontoxic. Starch is a kind of natural high molecular compound, variety of sources, biodegradable, non-toxic characteristics make it become an important research direction in the field of coal water slurry dispersant.In this paper, OSSA coal-water slurry dispersant was prepared by the radical polymerization using styrene sulfonic acid sodium and acrylic acid as graft monomers, oxidized starch as main chain and(NH4)2S2O8 as initiator. OSMA coal-water slurry dispersant was prepared by the radical polymerization using Sodium methallyl sulfonate and acrylic acid as graft monomers, oxidized starch as main chain and(NH4)2S2O8 as initiator. CSSA coal-water slurry dispersant was prepared by the radical polymerization using styrene sulfonic acid sodium and acrylic acid as graft monomers, cationic starch as main chain and(NH4)2S2O8 as initiator. CSMA coal-water slurry dispersant was prepared by the radical polymerization using Sodium methallyl sulfonate and acrylic acid as graft monomers, cationic starch as main chain and(NH4)2S2O8 as initiator. Coal water slurry structure was characterized by grafting ratio, grafting efficiency, FT-IR spectrum, GPC, etc. The dispersant was applied in Binchang coal samples, the properties of coal water slurry were characterized and analyzed by CWS apparent viscosity, Zeta potential, rheological property and adsorption amount, stability. The mechanism of the graft copolymer and coal particle was discussed.The experiment demonstrates that coal water slurry showed the better behavior when the amount of coal water slurry was 65wt% and the dosage of OSSA dispersant was 0.3wt%. Then, using the optimal dispersant content and pulp concentration, the apparent viscosity is 568 m Pa·s, the Saturated adsorption amount is 3.42mg/g, bleeding ratio is 6.2% after seven days. Coal water slurry showed the better behavior when the amount of coal water slurry was 65wt% and the dosage of OSMA dispersant was 0.3wt%. Then, the apparent viscosity is 819 m Pa·s, the Saturated adsorption amount is 2.26mg/g, bleeding ratio is 7.2% after seven days. Coal water slurry showed the better behavior when the amount of coal water slurry was 65wt% and the dosage of CSSA dispersant was 0.4wt%. Then, the apparent viscosity is 599 m Pa·s, the Saturated adsorption amount is 3.76mg/g, bleeding ratio is 5.8% after seven days. Coal water slurry showed the better behavior when the amount of coal water slurry was 65wt% and the dosage of CSMA dispersant was 0.4wt%. Then, the apparent viscosity is 798 m Pa·s, the Saturated adsorption amount is 3.45mg/g, bleeding ratio is 6.5% after seven days.Finally, the performance of the CSSA and OSSA dispersants were compared, The results show that the OSSA dispersant’s dispersion performance is better than CSSA dispersant, and the stability of the CSSA dispersant is better than OSSA dispersant; the two kinds of dispersants adsorption mechanism were investigated and discussed; the dispersant adsorbs on coal particle surface through the aromatic ring and hydrocarbon chain, while the hydrophilic group(hydrophilic starch long chain, sulfonic group, carboxyl) into the aqueous solution, it formed a stable adsorption layer and improved the coal particle surface hydrophilicity. Positive charge in the CSSA dispersant molecules formed the electrostatic attraction on the coal particles surface and promoted the adsorption; it has the three-dimensional repulsion and electrostatic repulsion between composite coal particle with adsorption layer, also can produce space steric hindrance, viscosity decreased and stability increased.