Experimental Study On Rheological Properties Of Tailings And Its Effect Factors

Rheology was first introduced to the world in 1920 s. When studying the industrial materials of rubber, plastic, paint, glass, concrete and metal, geological materials of rock, dirt, oil, minerals and biological material of blood, muscles, bones etc., scholars found that classical elasticity theory, plastic theory and Newtonian fluid theory have been unable to explain the complex characteristics of these materials, and thus the idea of rheology was born. With the development of economy and industrialization, rheology research also continues to expand, and has gradually infiltrated into many other disciplines, such as: rheology of polymer material, rheological fracture mechanics, rheology of soil, rock rheology, application of rheology and so on. Rheology has now developed into a new branch of mechanics, which mainly studies the deformation and flow patterns of materials under stress, strain, temperature, humidity, radiation and other conditions. In the theoretical research, it goes beyond the concept of uniform continuous medium, and begins to explore the rheological properties of discrete media, heterogeneous media and non-compatible elastic media. The continuous innovation of testing technology and the application of electronic computer play an important role in the development of rheology.The rheology of soil is an important branch of Engineering rheology and it involves the long-term safety of geological disaster prevention and control(such as landslides, etc.) and various types of large-scale projects(such as earth rock dam, underground engineering, foundation, slope, etc.). With the development of rheology, more and more attention is paid to the rheological properties of the soil. Domestic and foreign scholars have made a systematic study on the rheological properties of the soil, and have achieved gratifying results. However, few researches have been conducted on the rheological properties of tailings. The research objects in the present study are gold tailings in Yunnan Gold Mining Group, Heqing Beiya Mining Co., Ltd, copper tailings in Sichuan Liangshan Mining Industry Co., Ltd. and iron tailings in Yunnan Lincang mining company. The equipment used in this study are large coaxial cylinder rheometer etc. developed by Chongqing University, Chongqing coal mine disaster dynamics and control of the State Key Laboratory. A systematic study is carried out on rheological characteristics and influential factors of the above three kinds of tailings, a tailings slurry rheological model is established, and the influence factors of ore types, tailings particle size, slurry concentration and shear rate of tailings slurry rheological characteri stics are analyzed. The results obtained are as follows:(1)The rheological property testing instrument and working principle of debris flow are summarized. Based on the prototype of Brookfield rotating disc type flow meter and the working principle of the large coaxial cylindrical rotary rheometer, thia paper specifically developed tailings rheological property testing device, which provides a powerful technology for the rheological properties of tailings research.(2)Rheological properties of tailings and its influencing factors were obtained by rheological test of indoor tailings. Results show that:(1)The viscosity of tailings decreased first and then tended to be stable with time. The yield stress increases first and then tends to be stable with time. There are some differences in the viscosity and yield stress of different tailings. It is due to the difference of the rheological properties of slurry in different mineral components and content of different ore types.(2)The viscosity and yield stress grew with increasing slurry concentration. As the shear rate increased, The viscosity decreases but the yield stress increases. Especially when the slurry concentration is higher, the slope curve is steeper and when the tailings particle size, viscosity and yield stress increases, they decline with increasing slurry concentration and the slurry concentration curve becomes steeper.(3)In the rheological model of analysis of debris flow and its various influencing factors, according to the tailings rheological test results, comparative analysis of various kinds of rheological models, Bingham model is selected as the fluid properties of tailings flow model due to its simple undetermined parameters and clear physical meaning of rheological parameters.(4)According to the experimental results, the quantitative expression of the rheological model of tailings based on Bingham model is established, and the variation law of each coefficient in the rheological model of tailings is analyzed. Results show that with the concentration steadily increases, the viscosity and yield stress increased substantially and the relationship between the two shows a positive correlation of exponential growth. By the function fitting, the mathematical expression is:Coefficients B1 and B2 values vary within a stable range with B1 as 0.0425 and B2 as 0.035, which indicates that values of B1, B2 and other factors have little relationship. This is mainly decided by the pulp concentration, whose growth trend is relatively stable. The value of A1 is 55.5 to 176.21; the value of A2 is from 2023 to 3549.1 and their specific values cannot be defined. This shows that A1 and A2 can be easily affected by other factors besides the slurry concentration and particle size distribution.