Patent Publication Number: US-2021189876-A1

Title: Clean and efficient coal mining method

Description:
TECHNICAL FIELD 
     The present invention relates to a clean and efficient coal mining method, which is especially applicable to the field of solid waste treatment in mines. 
     BACKGROUND ART 
     As the national resources are consolidated continuously, more and more large-size mines with 10 million tons/year or higher annual yield emerge, and solid wastes generated in the mines increase explosively. The solid wastes in coal mines are mainly gangue, washing gangue, and coal ash. At present, the solid wastes are mainly disposed by centralized open dumping. Consequently, the solid wastes not only result in damages to the ecological environment in the mine field, but also bring severe threats to the living environment of people in the mine field. 
     According to the general planning and requirements of China, constructing new and modern coal mines is the direction of development of the coal industry in the future, and promoting safe and low-carbon operation and sustainable development of the coal mines is the general objective. Therefore, the approach of treatment of solid wastes in mines must be changed, and a new model of comprehensive utilization of solid wastes in mine fields as resources must be explored. In recent years, some approaches of comprehensive utilization of the solid wastes have been put forward by coal mine enterprises, such as power generation using solid wastes, production of building materials, recovery of valuable minerals, production of chemical materials, soil improvement, production of fertilizers, backfilling (including building backfilling, low-lying land and waste-land backfilling, mine gob filling, reclamation of subsidence area in coal mines), and road building, etc. However, those approaches can&#39;t solve the solid waste treatment problem thoroughly. At present, there is no coal mining method that can be used to treat surface solid wastes quickly while avoiding lifting up downhole solid wastes. 
     CONTENTS OF THE INVENTION 
     Technical problem: the object of the present invention is to overcome the drawbacks in the prior art, and provides a clean and efficient coal mining method that can be used to treat surface solid wastes quickly while avoiding lifting up downhole solid wastes. 
     Technical scheme: to attain the technical object described above, the clean and efficient coal mining method provided in the present invention comprises the following steps: 
     a. calculating the volume of existing solid wastes produced in a mine, and the solid wastes include downhole gangue, surface gangue, and coal ash; 
     b. arranging a long-segment working face for filling solid wastes in the mine in the coal seam in the mine field, arranging short-segment working faces I and II in width w at the two sides of the long-segment working face respectively, commissioning the equipment, including coal cutter, hydraulic support and belt conveyer, at the short-segment working faces I and II, mining at the short-segment working faces I and II simultaneously, backfilling with the existing solid wastes in the mine and the gangue produced in the mining, and supporting the edges of the filling face and the solid coal side with anchor rods while retaining roadways at the two sides of the filling face; 
     c. utilizing a heading machine to excavate open-off cuts between the short-segment working face I and the short-segment working face II after the mining at the short-segment working faces I and II is finished, so that the roadways retained at the short-segment working faces I and II and the open-off cuts constitute a long-segment working face mining system; 
     d. mining at the long-segment working face I, transporting the mining equipment at the short-segment working face I to a short-segment working face III at the left side to mine, and transporting the mining equipment at the short-segment working face II to a short-segment working face IV at the right side to mine, and transporting the gangue produced in the mining at the long-segment working face to the short-segment working faces III and IV to fill, letting a gob formed after the mining at the long-segment working face I is finished collapse directly; 
     e. excavating open-off cuts respectively after the mining at the short-segment working faces III and IV is finished, arranging long-segment working faces II and III respectively, and repeating the step d, so that continuous mining that consists of backfill mining at short-segment working faces, and efficient stopping at the long-segment working faces is realized, and the mining of the entire coal seam in the mine field is completed in that way. 
     All short-segment working faces have the same width, and the width can be determined with a formula w=Q/(2l*h), and w≤60 m, and the specific dimension depends on the quantity Q of the solid wastes, where, l is the length of the short-segment working face, and h is the mining height at the short-segment working face. 
     All long-segment working faces have a width of 150 m˜300 m. 
     The roadways retained after the filling of the short-segment working faces have a width of 4˜6 m. 
     Beneficial effects: with the above technical scheme, the present invention has the following advantages over the prior art: 
     (1) All solid wastes in the mine can be filled to the short-segment working faces, so that the problem of surface solid waste dumping is solved while the requirement of avoiding the lifting of downhole solid wastes is attained; thus, the cost of gangue treatment is reduced, the damages to the ecological environment are mitigated, and the sustainable development of the mine is improved. 
     (2) The short-segment working faces at the two sides are backfill-mined at the same time after the stopping at the long-segment working face is finished, and thereby a continuous mining system that consists of backfill mining at the short-segment working faces and efficient stopping at the long-segment working faces is realized. 
     (3) The solid wastes are utilized to fill the gobs at the short-segment working faces to form roadways; thus, coal pillars are eliminated and the resource recovery rate is improved. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of the clean and efficient coal mining method according to the present invention. 
     
    
    
     In the FIGURE:  11 —short-segment working face I;  12 —short-segment working face II;  13 —short-segment working face III;  14 —short-segment working face IV;  21 —long-segment working face I;  22 —long-segment working face II;  23 —long-segment working face III;  3 —retained roadway;  4 —open-off cut;  5 —gob. 
     EMBODIMENTS 
     Hereunder the present invention will be further detailed in an embodiment with reference to the accompanying drawings. 
     As shown in  FIGS. 1, 2 and 3 , the clean and efficient coal mining method provided in the present invention comprises the following steps: 
     a. calculating the volume of existing solid wastes produced in a mine, and the solid wastes include downhole gangue, surface gangue, and coal ash; 
     b. arranging a long-segment working face  21  in width of 150 m˜300 m for filling solid wastes in the mine in the coal seam in a mine field, arranging short-segment working faces I  11  and II  12  in width of w at the two sides of the long-segment working face  21  respectively, wherein, all short-segment working faces have the same width calculated with a formula w=Q/(2l*h), and w≤60 m, the specific dimension depends on the quantity Q of the solid wastes, wherein, l is the length of the short-segment working faces, and h is the mining height at the short-segment working faces; commissioning the equipment, including coal cutter, hydraulic support and belt conveyer, at the short-segment working faces I  11  and II  12 , mining at the short-segment working faces I and II simultaneously, filling with the existing solid wastes in the mine and the gangues produced in the mining, supporting the edges of the filling face and the solid coal side with anchor rods while retaining roadways  3  at the two sides of the filling face, wherein, the roadways  3  retained after the two short-segment working faces are filled has a width of 4˜6 m; 
     c. utilizing a heading machine to excavate open-off cuts  4  between the short-segment working face I  11  and the short-segment working face II  12  after the mining at the short-segment working faces I  11  and II  12  is finished, so that the roadways  31  retained at the short-segment working faces I  11  and II  12  and the open-off cuts  4  constitute a long-segment working face mining system; 
     d. mining at the long-segment working face I  21 , while transporting the mining equipment at the short-segment working face I  11  to a short-segment working face III  14  at the left side to mine, and transporting the mining equipment at the short-segment working face II  12  to a short-segment working face IV  13  at the right side to mine, and transporting the gangue produced in the mining at the long-segment working face  21  to the short-segment working faces III  14  and IV  13  to fill, letting a gob  5  formed after the mining at the long-segment working face I  21  is finished collapse directly; 
     e. excavating open-off cuts respectively after the mining at the short-segment working faces III  14  and IV  13  is finished, arranging long-segment working faces II  22  and III  23  respectively, and repeating the step d, so that continuous mining that consists of backfill mining at short-segment working faces, and efficient stopping at the long-segment working faces is realized, and the mining of the entire coal seam in the mine field is completed in that way.