Abstract: Long-term experience of practical applications and lab tests implies that the engineering characteristics of tailings is related to some factors such as mineral composition, damming layout, sedimentary characteristics of the ore pulp, and more closely to the particle size distribution of tailings. In order to analyze the upriver-type tailings variations of the particle composition and its influence on the tailings engineering properties after discharging, depositing, sorting, a series of tests is performed to determine the particle-size distribution, mechanical properties and permeability of tailings at different positions on depositional beach face, and the influence of the fine particles (particle diameter less than 0.075 mm) content on the engineering properties of tailing is analyzed. It is found that as the distance from the tailings beach crest increases, the composition of fine particle gradually increases, grain size distribution situation changes from normally to well-graded, then again normally-graded; void ratio initially decreases and then increases; the tailings cohesion grows gradually as the content of fine particles increases, whereas internal friction angle changes within a relatively small range; the permeability coefficient is significantly influenced by the fine particle content, and decreases rapidly with the increase of the content.

Key words: tailings, fine particle content, grain size gradation, mechanical properties, permeability coefficient