Paste Proportion Test And Pipeline Transportation Simulation In Coal Mining

In this paper,by optimizing the ratio test,chemical analysis,pipeline modeling and numerical simulation analysis,we obtained the ratio of the composite cementitious material and the paste filling material.In consideration with the filling condition of Dai-zhuang coal mine,we studied the basic properties and rheological properties of the paste.Through a numerical simulation of the pipeline process by FLOW-3D,the pipe pressure of each location was calculated,so does the safety thickness of tube wall,for the safety of packing operation.The main conclusions are as follows:(1)Based on single factor method,we designed the experimental scheme of composite Cemented materials,which are silicate cement,sulphoaluminate cement and gypsum.Through compressive strength test,we found that the composite cementitious materials of portland cement,sulfate aluminate cement and plaster,for the control of setting time,early and later strength of cementitious materials.According to the analysis of XRD and SEM,the hydration products of composite Cemented materials are mainly calcium alum in the beginning,and C-S-H and CH gels are main ones in the middle and later stage.(2)The mixture of coal gangue,fly ash and optimized mix is designed by using single factor method.The experiment shows that the increase of fly ash will lead to a increase in slump,coagulation time and the later strength of paste,and a reduce in its delamination and the early strength.The corresponding scheme is Z3 with a ratio of composite Cemented material,fly ash and coal gangue is 1:4:7,and the concentration is 81%.The slump is 18.9cm,the layered degree is 1.7cm,the initial setting time is 4h 16min,the final set time is 5h 12min,the early strength is 0.22MPa,the late strength is 1.81 MPa,the density is 1725kg·m-3,the yield stress is 57.70Pa,the viscosity is 4.875Pa s.(3)The paste filling material was applied to carry out the pipeline transportation test.By monitoring the density,flow rate and differential pressure of the paste filling material in the conveying process,the basic properties and rheological properties of paste filling materials are obtained.The FLOW-3D was used to simulate the conveying process in combination with the situation of Daizhuang coal mine,and by which a plunger pump model suitable for the paste filling was designed.According to the simulation results,the pipeline pressure distribution is obtained and maximum pressure,the safety thickness of the pipe wall is calculated as 12.6mm,hence.(4)Z3 paste filling material was used to carry out the conveying operation in Daizhaung,and by monitoring the pressure condition of the pipe,the performance of the paste filling material was measured.The pressure at the bottom of the borehole is 9MPa when the working face is 2000m from the fill hole.The lateral pressure of the bottom of the hole was 0.12MPa.After 4h transmission,the material collapse degree is 18.4cm,and the stratification degree is 1.2cm,which can meet the filling requirements.According to the results of pressure monitoring,a more secure monitoring method is put forward to ensure the safe filling operation.