One of the important directions of the research on coal washing is developing the non-toxic reagents with strong force and high selectivity. Compared with model strains, yeast designated Y21 as surface modifier for fine coal was isolated from lignite by traditional microorganism separation. Colony morphology, physiological and biochemical characteristics and some molecular sequence fragments show that the strain Y21 was Rhodotorula mucilaginosa. Through zeta-potential measurements and contact angle changes of coal samples caused by strain Y21, it was shown that strain Y21 can be selectively adhered onto the fine coal surface through the electrostatic interactions and the hydrophobic interactions. These observations lead to the conclusion that the adhesion of the yeast onto the coal surface could change zeta potential and the contact angle of coal particles. For both coal samples, the contact angle was sharply increased respectively in the pH range 3-4 and 2-4 as a result of Y21 strain adsorption. This indicates that as a result Y21 strain adsorption the coal surfaces have become more hydrophobic. These results indicated that the modified flotation and flocculation rate of fine coal particles were improved using the strain Y21 through changing the surface characteristics of coal.

The lignin condensated sulfonated naphthalene (abbreviated as LCSN) was prepared by condensation reaction. The electrical conductivity and the weight molecular of LCSN were determined by electrical conductivity meter, and Ubbelohde viscosimeter, and Critical Micelle Concentration (abbreviated as CMC) and HLB of the modified lignin were calculated. LCSN was characterized and verified by Fourier and scanning electron microscope, transform infrared spectroscopy (abbreviated as FTIR). SEM images revealed morphology of modified lignin. Under the same dosage, compared with raw material, concentration of lignite CWS used LCSN as an additive increased by 4.1%, which reached the same concentration of CWS as Naphthalene dispersants.

The utilization of high moisture, high volatile low rank coals such as lignite is gaining importance day by day to meet the growing demands of coal for the energy sectors. For the combustion of pulverized material it appears essential to dry lignite. Further, lowest possible ash and moisture as well as high heat content are desired for combustion. The present work gives the details of the preparation of a product of higher calorific value by thermal treatment of Inner Mongolia lignite. The low-temperature pyrolysis characteristics were carried out on the regularities of pyrolysis temperature and holding time on the product yield of dry distillation of lignite by using aluminium retort method. The result shows that the suitable pyrolysis condition of lignite is 450 ~ 510 °C, holding time for 30 min. The ratio of aliphatic and aromatic groups of 400°C semi-coke obviously decrease 53.1% and 11.8% compared with raw coal. The degree of aromatization of semi-coke is gradually increased and aromatic nucleus condensation degree increases. The retort process of lignite is a dehydrogenation, deoxidization and carbon-rich process.