Abstract: In order to overcome the difficulty in separation of clay minerals such as montmorillonite in fine coal flottation process, test on flotation of the primary slime of Dongpang Mine Coal Preparation Plant is conducted using sodium silicate as depressant and Kerosene as collector and by means of intensified pulp dispersion through strong mechanical agitation in combination with selective control of flotation reagent. Meanwhile, the principle of se3lective control is characterized quantitatively by measuring adsorptive capacity of reagent and contact angle. Test result shows that: the selectivity of sodium silicate adsorbing onto coal and montmorillonite surface can be enhancedby adding first collector and then depressant; a wide difference between coal and montmorillonite particle surfae in wettability can help promote the separation of coal and montmorillonite; when the enhanced pulp dispersion and selective control method is used in slime flotation, the concentrate yield and ash are respectively 47.03% and 14.21% with a perfect index reaching 30.83%; and even with a yield of concentrate equal to that before renovation is made, the concentrate ash can be noticeably reduced.