Study On Surface Adsorption Behavior Of Coal Water Slurry Of Bituminous Coal

In this paper, additive evaluation scheme for Ningxia low rank coal was formulated by studying matching principle on surface tension, pH, critical micelle concentration, intrinsic viscosity, adsorption of the additive solution and coal water slurry (CWS) property. The study has an important significance for additive evaluation and the ratio of additives has been defined. The conclusions are as follows:(1) Naphthalene sulfonate-formaldehyde additive has better adsorption in 10 coals with good adaptability. By mixing naphthalene sulfonate-formaldehyde with other additives could improve the performance of additives. Because ignin sulfonate additive has large limit adsorption differential in coal surface so that this additive has poor adaptability. Because of the low price, mixed additives of ignin sulfonate can reduce pulp costs. When the mass ratio of naphthalene sulfonate-formaldehyde and ignin sulfonate additive is 2:1, the slurryability be significantly improved. By comparing the limit adsorption amount of three, NDF showed poor adaptability for low rank coal in Ningxia.(2) Surface tension is an important physical parameters of surfactant, and the surfactant of additive was affected by that. So experiment can use surface tension to evaluate the additive. The additive has high matching with low rank coal if the concentration of additive solution is 0.1 g-mL-1, and the surface tension of additive solution is in 55 mN·m-1～65 mN·m-1. Slurry experiments show that if the measured pH value in the range of 7.65～8.7, the additive could significantly improve the slurry properties.(3) Slurry experiments indicate that coal water slurry additive affects coal rod milling. Coal particle sieved ratio show that, the ratio of particle size less than 200 mesh could be improve 9% when adding naphthalene sulfonate-formaldehyde. But the ratio will be reduced 5% when adding ignin sulfonate additive. The problem of slurry grouting due to coarse particles in actual production could be resolved by changing adding ratio of these two types of additives.