Research On Proportion Optimization And Flow Characteristic Of Backfill Paste In Mine Sites

Abstract:Development and utilization mode of traditional metal mineral resources triggered geological disasters, environmental destruction and waste emissions, had become an important factor restricting sustainable development and utilization of China's mineral resources and the healthy development of the mining industry. To completely relieve the bottleneck restriction of resources, energy, environment, realising the transformation of resources, energy consuming model to saving model, and change of the treatment after pollution pattern, it needs to develop the green, sustainable resource development mode which has the characteristics of vigorously developing clean production, resource efficient mining and waste recycling. Paste backfill breaks through the barrier of traditional backfill technology, and will be the important technology carrier which can realize safe, clean and efficient mining. The main characteristics of the paste backfill:filling slurry not segregation, not precipitation, and stope dehydration less, or even no dehydration, filling body strength is growing rapidly, high quality fillbody, high efficiency, low cost, and improve underground working environment. Paste backfill will be the inevitable future development of clean mining. The main research results were as follows:(1) Combining with the design and application status of paste backfill in underground mines, the backfill materials, processes and technology and other aspects were analyzed. According to the paste backfill characteristics, the following points of high concentration full tailing paste had been systematic expounded:slurry filling mechanism and material mix design principles, filling paste flow characteristics and rheological parameters determination methods, filling paste preparation technology and equipment, transportation technology and equipment.The paste backfill is widely used for its advantage compare to other backfill methods.(2) From the theoretical point of view, the rheology models of backfill paste based on the cylindrical and cone slump and the relationship of the rheological parameters and slump was inspected by slump tests. The results showed that:cylindrical slump test and the model are more accurate for describing the rheological parameters of the high concentrations backfill paste; compare to the form of the mathematical formulas, cylindrical slump model is simpler than cone slump model; because the geometry of the cone container is more complex than cylindrical container, it is more difficult to fill the paste, and during the cone slump test, a lot of bubbles formed during the filling, it will definitely affect experimental results; during the cone slump test, the shape of the paste is not continuous, it is more obvious for the high yield stress paste; the design and preparation of the cylindrical container is easier than the cone container.(3) Forecasting model is established based on the principal component analysis and BP neural network. Firstly, the input data was preprocessed and number of network input factors was reduced, the input factors were unrelated to each other, but the main message remains in the main components. The network structure was simplified, and network learning speed was improved; the accuracy and the quality modeling were improved. SPSS software is introduced into backfill design and statistics, and its statistics theory and methods of analysis can enhance the mine management and research. The results showed that:the error between desired output and PCA-BP based predicted value is controlled at less than5%; and compare to the BP based predicted value error, the PCA-BP model is more accurate.(4) The principle of the backfill paste mix proportion is established, and setting the paste mass concentration, sand-cement ratio, cement consumption and stick frosted/tailings ratio as main parameters of the backfill paste, setting the backfill paste fluidity, filling body strength and the cost as the optimization target. Optimization model of the mix proportion based on orthogonal design, uniform design and formula experiment design were established, comparing the experiments and site testing, the outcome and backfill practice nearly same. The results showed that:with paste concentration, cement consumption and stick frosted/tailings ratio increases, the slump is about250mm-300mm, and it's within the backfill requirements; increasing the stick frosted is useful to the paste fruity, when the frosted/tailings ratio is0.75, the paste has a good fluidity; with f consumption of cement, it can help reduce the hydraulic gradient, thereby reducing the transportation resistance loss; in the backfill paste, cement play a role as combining agent and lubricating agent, it is useful to the paste consolidation and it can increase the strength of the paste, as well as improve the paste transportation, et al.(5)According to lubrication theory and deposition theory, the geometry prediction model of backfill paste flow deposition was established, after the experiment checking, the predicted and measured results were nearly same. The results showed that the model can be used to predict geometry shape of backfill paste deposition in the goaf, and then guide the paste backfill practice; the physics experiment platform of backfill paste flow and deposition based on similarity theory is established, and the inhomogeneity of the paste filled-body after deposition is studied, and it can provide some theoretical guidance to the paste backfill practice.