Synthesis And Application Of Modified Lignosulfonate As Coal Water Slurry Dispersants

Coal water slurry was a kind of new and clean coal fuel technology developed in the 70s of the 20's century. In Chinese energy developing plan, coal water slurry has very important strategic meaning. Dispersant is the key factor of high concentration and high stability coal water slurry. Naphthalenesulfonate-formaldehyde condensate, polyolefine sulfonate, polycarboxylate, lignosulfonate and other anion dispersants are the common industry coal water slurry dispersants. The lignins dispersants for coal water slurry are mostly the byproducts from paper industry. Lignin has the advantages of abundant of raw material, well coal water slurry stability and less separating water. However, lignin dispersant also has the disadvantages of high viscidity and low fluidity. So modifying the lignin, enhancing the ability of seperating and dropping the slurry's viscidity had become the important point of the research.Firstly, the industry analysis and element analysis of ten kinds of coal from Neimenggu were carried out. Effect of the grain size distribution on the slurry properties was studied, and the best grain size distribution to the selected coals was received.Secondly, sulfonation, sulfornation and condensation, sulfomethylation and condensation, graft copolycondensation and multi-dispersant modifications were studied. The copolycondensation of the lignosulfonate and naphthalenesulfonate was studied preliminarily.Through introducing more sulfonic group into the lignosulfonate molecule, the property of the products was enhanced. Dispersant with good dispersing ability and stability was achieved. The effects of sulfonating time, sulfonating agent and its concentration on the propertied of modified lignosulfonate dispersants were studied.The reaction conditions of sulfornation and condensation were optimized by orthogonal experiment. IR spectra was employed for characterizing the structure of the products. The results showed that the amounts of the sulfonating agent and condesating agent, the value of pH in the system were important. Optimized reaction conditions were that the weight of the sodium sulfite and the formaldehyde in the reaction all accounting 50% of the weight of the lifnosulfonte, the pH of the sulfonating reaction was 11.5 and the pH of the condensating reaction was 10. The proper weight of the catalyst accounted 3% of the weight of the lignosulfonate.Sulfomethylation and condensation could enhance the dispersing ability and stability of the products. The suitable reaction conditions were that the pH of the sulfomethylation reaction was around10.5, the best pH of the condensate reacting was around 10.5, the temperature of the condensate reacting was 70℃, and the adding of the catalyst could make the dispersing property and stability property of coal water slurry better.Lignosulfonte was oxidated and then grafted with crylic acid and at last condesated with formaldehyde, the reaction conditions was optimized. IR spectra was employed for the structure of the products. The appropriate factors were received. The proper amounts of peroxide hydrogen, crylic acid and formaldehyde were 10%, 50% and 40%. The better oxidation time was 1 hour, and the better graft copolymerization time was 2 hours.Lignosulfonate and naphthalenesulfonate-formaldehyde condensate were used together as the coal water slurry dispersant. Different dispersants could make up another dispersant's disadvantages and product coal water slurry with high performace.The col-condensation of the lignosulfonate and naphthalenesulfonate was studied preliminarily. The reacting conditions selected were not suit to the modified reaction. At last, the modified lignosulfonate dispersants were applied in several kinds of coals'slurry. The better amount and adaptability of the dispersants were tested.