Abstract:

The maximum filling geometrical line of the system above +0 m middle section in a gold mine in Jiangxi was close to 40, and it was difficult to realize the self-flowing of the filling slurry, and there were a large number of recoverable resources in this area.In view of the above problem it was proposed to use the large line pressure filling technology to achieve filling of +0 m middle section of the mine, so that the above resources could be recovered.In order to determine the optimal process parameters of the filling slurry pipeline, this paper firstly analyzed the basic properties of the tailings, the main chemical composition of the graded tailings was SiO₂ and Al₂O₃.This component was beneficial to increase the strength of filling body.The physical properties of the graded tailings was 2.74, the bulk density was 1.45 t/m³, and the porosity of the loose tailings was 47.1 \mathrm{\%} .The particle size composition test results show that -37 μm only accounts for 5.62 \mathrm{\%} , and -74 μm accounts for 14.36 \mathrm{\%} , indicating that the fractionated tailings has less fine particles, the whole grain large diameter is an ideal filling aggregate, and selected the corresponding hydraulic model for pipeline transportation.Through the hydraulic calculation of the filling slurry pipeline, the critical flow velocity under different conveying conditions was determined.Combined with the mining filling process parameters, the resistance loss along the pipeline under different filling conditions was calculated.According to the existing engineering conditions of the mine and the scope of filling services, two sets of pipeline transportation system layout schemes were designed.Scheme 1: The longest filling pipeline in the middle section of 100 m was 1 728 m, the geometric filling line was 42.1, the conveying resistance was 2.84 MPa (concentration was 68 \mathrm{\%} , the diameter was 100 mm).The longest filling pipeline in the middle section of 75 m was 1 956 m, the geometric filling line was 29.6, the conveying resistance was 2.88 MPa.The longest filling line in the middle section of 50 m was 1 668 m, the geometric filling line was 18.3, and the total head loss was 1.86 MPa. Scheme 2: The longest filling pipeline in the middle section of 100 m was 1 551 m, the geometric filling line was 37.8, the conveying resistance was 2.48 MPa (concentration was 68 \mathrm{\%} , the diameter was 100 mm).The longest filling pipeline in the middle section of 75 m was 1 852 m, the geometric filling line was 28.1, the conveying resistance was 2.67 MPa.The longest filling line in the middle section of 50 m was 1 731 m, the geometric filling line was 19, and the conveying resistance was 1.99 MPa.Compared the two pipeline transportation system layout schemes and pipeline transportation resistance loss, filling geometric line was calculated.The scheme 2 was determined,and the 120 m adit filling slurry pipeline transportation scheme was the best pipeline transportation system layout scheme for the project.At the same time, combined with the filling slurry hydraulics calculation results and the filling slurry pipeline layout scheme, the optimal working speed of filling slurry pipeline transportation, parameters of filling slurry and pipeline parameters were determined.Finally, combined with the resistance loss along the pipeline, the layout scheme of the pipeline transportation system and the transportation parameters of the filling slurry pipeline, the type of filling pump and related technical parameters were selected, which the pump outlet pressure was 5 MPa.The pump flow rate was 60 m³/h.After the on-site industrial application, all the operation indexes met the design requirements, and the operation condition was good, and the volume of filling goaf was 1.396 m³(cement filling accounted for 20 \mathrm{\%} and water sand filling accounted for 80 \mathrm{\%} ), which could increase the economic benefit of the mine by 10.12409 million yuan.

Key words: large fill-times-line, pressure filling, minefill, pipeline transportation, transport resistance, critical velocity