关键词: 金尾矿砂, 物化性质, 表面改性, 黏聚力和内摩擦角, 混凝土集料

Abstract: Gold tailing sand is a solid waste discharged from gold ore dressing operation. Its open storage not only occupies land， pollutes the environment， but also causes great safety hidden danger. Using gold tailing sand instead of natural sand as aggregate for concrete can not only reduce the exploitation of natural sand， but also realize the utilization of solid waste resources. The basic physicochemical properties of tailing sand and its physicochemical properties as concrete aggregate are analyzed regarding the tailing sand of a gold mine in Shaanxi Province as the research object. On the basis of this research， the surface of gold tailing sand was modified by modifier， and the modified gold tailing sand replaced part of river sand as the total aggregate to carry out the test of concrete mix. The results showed that the gold tailings sand is of fine particle size with excessive content of clay， sharp edges and corners， which is harmful for the the performance of concrete. Coating with modifier can effectively reduce the cohesion and internal friction angle between gold tailing sand particles. When the coating amount of SA is 0.015 times of sand dosage， the cohesion between gold tailings particles decreases by about 56%， and the internal friction angle decreases by about 13%. Under the condition of replacing 30% river sand， the water consumption of the concrete sample without coarse aggregate prepared by the surface modified gold tailing sand is lower， but the expansion and strength are obviously higher. When the sand-cement ratio is 1.5， the strength of concrete mixed with modified gold tailing sand is more than 20% higher than that without modification. By adjusting the ratio of sand to cement， water consumption and dosage of water reduction， the concrete materials without coarse aggregate with different strength grades and fluidity can be prepared by replacing some fine aggregates with modified gold tailing sand， so as to meet the requirements of different construction projects.

Key words: gold tailings sand, physical and chemical properties, surface modification, cohesion and internal friction angle, concrete aggregate