Synthesis And Characterization Of Modified Lignosulfonate Sulfuric Acid For Coal Water Slurry

Dispersant is an important component in the preparation process of the CWS,and whether the dispersant has good slurry performance directly affects the advantages and disadvantages of the obtained slurry performance of the CWS.When lignosulfonate is used as a dispersant,it has low matching degree with low rank coal molecules,large apparent viscosity and low pulping concentration.In this paper,acetone and formaldehyde are used as modifiers,through sulfonation reaction and condensation reaction.Synthetic molecular structure contains new high-performance additives such as sulfonic acid groups,carbonyl groups,hydroxyl groups,ether groups,and other hydrophilic groups,and its low-rank coal pulping performance under the conditions of a CWS dispersant was investigated.Pulp mechanism.Research is specifically conducted from the following three aspects.Synthesis and characterization of modified lignin dispersants.Lignosulphonate was used as the reaction raw material in the experiment,anhydrous sodium sulfite was used as the sulphonating agent,acetone and formaldehyde as modifiers,and the molar ratio,sulphonation time,condensation temperature and condensation time including raw materials were explored by orthogonal test.The influence of different factors on the number of functional groups in the sodium lignosulfonate molecule during the sulfonation and condensation reactions,and the low-rank coal slurry viscosity characteristics of Shendong,to determine the optimum process for synthesizing the modified dispersant condition.The results showed that the performance of the modified dispersant was best when the raw material sodium sulfite:n acetone was 0.6:1,the sulfonation time was 80 min,the condensation time was 5 h,and the condensation temperature was 90 °C.Preparation and performance evaluation of CWS.The particle size was analyzed,and the CWS was prepared by selecting the ratio of the thickness of coal particles that meet the requirements for the particle size distribution.The dispersant dosage was optimized when the performance of the CWS was optimal.Under the same addition amount,the performances of the naphthalene dispersant and the aliphatic dispersant slurry were compared.The results show that when the ratio of coarse to fine particles of the coal sample is 7:3,it is in accordance with the “double peak” particle size gradation;when the additive amount of the modified sodium lignosulfonate is 0.5%,the slurry performance is the best.When the addition amount was 0.5%,the properties of the slurry prepared from the three types of dispersants were compared,in which the modified lignosulfonate dispersant had the highest sticking concentration of 65.36% and the fluidity showed continuous flow.System Zeta potential measurement and adsorption mechanism study.The Zeta potential of the system before and after the mixing of the coal sample and the dispersant was measured by a microelectrophoresis meter,and the isoelectric point of the solution was calculated to investigate the stability mechanism of the slurry.The UV-Vis spectrophotometer was used to determine the absorbance change of Shendong Coal before and after adsorbing the three types of dispersants.The adsorption amount of different kinds of dispersants on the surface of coal particles was calculated by the formula and the adsorption model was judged.The results showed that the system had the strongest electronegativity and was more easily adsorbed on the surface of coal particles after the addition of modified lignosulfonate.When the amount of dispersant was 0.5%,the modified lignin dispersant and naphthalene dispersant were used as coal samples.Adsorption of aliphatic dispersants has basically saturated adsorption amounts of 4.52 mg/g,4.13 mg/g,and 3.61 mg/g,respectively.Coal samples have the largest adsorption amount of modified lignin sulfonates and the fastest adsorption rate.The coal particles are more easily adsorbed and modified by the lignin sulfonate dispersant;and compared with the three types of dispersants,the modified lignin sulfonate adsorbed on the surface of the coal particles more conforms to the Langmuir adsorption model,and the adsorption rate constant is the largest,indicating that the coal sample is correct.Its adsorption capacity is stronger.