Stoping method for remaining pillars in goaf of underground mine
Technical Field
The invention belongs to the technical field of underground mine exploitation, and particularly relates to a stoping method of a residual stud in a goaf of an underground mine.
Background
The mining technical conditions of the underground residual ore pillars are extremely complex, and the mining technical conditions are a great problem in the current mining technology. At present, when a plurality of mines recover residual ore resources, the expected effect is often not achieved due to the technical or economic difficulties.
At present, most underground mines at home and abroad develop mineral resources by using an open-stope subsequent filling mining method, and no matter a shallow hole shrinkage stope subsequent filling mining method or a sublevel open-stope subsequent filling mining method, ore blocks are divided into ore rooms and studs, and the ore rooms are firstly stoped and filled and then the studs are stoped. The mining method is mainly applicable to: firstly, the ore and the surrounding rock are stable and do not fall down naturally in the stoping process; the thickness of the ore body is preferably thin or medium thick; the dip angle of the ore body is over the steep dip; the ore has no caking and naturalness; the surface is not allowed to collapse. Since the advent, the mining method has been popularized and applied in many mines, and still many mines are using the mining method at the present stage, such as Huangshan lead-zinc-gold-silver ore of Shandong Jinxitai group, Fengyang Jinpeng mining industry of Anhui, lead-zinc-gold-silver ore of Jiangsu gold-flame Aijing mountain, strontium ore of Yunan copper factory, etc.
When a mine is divided into a room and a stud, a dividing method with a large room proportion and a small stud proportion is generally selected, so that the defects of low ore production efficiency, high ore dilution rate, poor operation safety and the like are inevitably caused when the stoping of the room is finished and the stud is stoped after filling, the safety and high-efficiency mining of the stud is difficult to realize, and particularly, the stud mining always troubles many mine enterprises when rare metals, precious metals and high-grade ore vein are mined. In view of the above difficulties, many mines are forced to abandon the recovery pillars, so that a large number of pillars are left after the stoping of the chamber is finished, and natural mineral resources are seriously wasted.
A finite element analysis program is adopted in a goaf ore pillar safety stoping technology and practice published in the No. 7 of metal mines 2008 to analyze stress of a goaf roof and surrounding rock masses in the stoping process, and a stoping scheme is demonstrated, and results show that (1) ore pillar stoping of 'mining one and one' is carried out, the maximum main stress is in the failure strength of rocks, the goaf is enlarged and influenced by weathering, surrounding rocks of the roof can generate local bulk caving, the bulk caving cannot be developed, and the influence on the ground pressure of the upper goaf is small. (2) And (3) carrying out total stoping of the ore pillars, wherein the maximum main stress exceeds the failure strength of rocks, the exposed area of a conjuncted dead zone formed after stoping reaches more than 3700m2, and roof surrounding rocks fall in a large range and even cause geological disasters. (3) After the dead zone is treated (waste rock filling and cemented filling conditions are not met), all ore pillars are stoped, and the influence of ground pressure is small. The ore adopts a scheme of completely stoping the ore pillars after dead zone treatment, the dead zone after stoping is also filled with waste rocks in time, but long pillars need to be reserved for ensuring safety, and the final ore stoping rate is less than 60%.
Chinese patent 201611105285.0 discloses a space pillar recovery method for reconstructing a covering layer by combining goaf waste rock filling and top surrounding rock caving, which has the technical scheme that: firstly, filling a goaf formed when a stoping chamber is filled with waste rocks, and reserving a certain space; secondly, dividing the stud into a plurality of layers in the vertical direction, tunneling a rock drilling roadway in the center of the bottom of each layer, and caving the surrounding rock at the top of the stud to form a covering layer; then, an upward fan-shaped medium-length hole blasting scraper is adopted to carry out ore removal, and the ore pillars are sequentially advanced and retreated in the layer from top to bottom. Although the method realizes ore drawing under overlying strata, reduces the exposed area of a goaf and recovers part of pillars, the method also has the following technical defects:
(1) according to the theory of ore drawing ellipsoid, when carrying out shoveling ore drawing, because the layering is high, when about 1/3-1/2 ore is discharged, the ore is mixed into the barren rocks until the discharged barren rocks are completely discharged, the ore drawing is forced to stop, and the permanent loss of the ore is caused.
(2) The two sides of the stud are filled waste rocks, and when the shoveling and ore removal are carried out, the ores at the upper part can not be discharged completely, the waste rocks at the two sides begin to flow to the ore removal roadway under the action of self weight, so that the ore dilution is serious;
(3) the shoveling and ore removal are carried out in a single-head roadway every time, so that a through air flow cannot be formed, the ventilation of a working surface is difficult, and the operation safety condition is poor;
(4) and fan-shaped medium-length hole ore falling and scraper ore removal are adopted in each layer, so that rock drilling and scraper equipment needs to be carried back and forth, a large number of equipment operation channels need to be tunneled, and the mining accurate cutting engineering quantity is greatly increased.
Disclosure of Invention
The invention aims to provide a stoping method of an underground mine goaf left stud, aiming at the defects in the prior art, and the method realizes the purposes of improving the ore recovery rate, reducing the ore dilution rate, reducing the mining process quantity, avoiding the large exposed area of the goaf and improving the working environment of a working face by arranging a bottom ore removal structure, reasonably arranging a cutting raise and a layering height and reserving ores in a stope.
In order to achieve the purpose, the stoping method of the underground mine goaf remaining stud adopts the following technical scheme:
the invention relates to a stoping method of a residual stud in a goaf of an underground mine, wherein a stud is arranged in an ore body, two sides of the stud are provided with ore rooms, a middle section haulage roadway is arranged on the footwall of the ore body, and the stoping method is implemented by adopting the following steps:
1) after stoping of the chamber is finished and a filling body formed by adopting tailing cemented filling reaches specified maintenance strength, tunneling an ore removal roadway into a stud at one side of a middle section haulage roadway along the direction vertical to the direction of the ore body to reach a hanging wall rock contact surface on the ore body; the curing strength is generally 1.5 MPa;
2) tunneling a cutting raise upwards along the hanging wall ore rock contact surface at the end part of the ore removal roadway, wherein the cutting raise penetrates through the upper middle section air return roadway and is used as an air return channel for the initial drilling and blasting free surface and the later layered stope operation;
3) drilling fan-shaped medium-length holes upwards along the top of a mine removal roadway in a stud, wherein the included angle alpha between the fan-shaped medium-length holes at two sides and the horizontal direction is more than 45 degrees and generally ranges from 45 degrees to 60 degrees, a cutting raise and the mine removal roadway are taken as free surfaces, a horn mouth-shaped bottom structure is formed after row-by-row blasting, a scraper is adopted to discharge part of ores, the rest of ores are temporarily reserved in the stud space to serve as a working platform for continuous upward mining, and the height of a rock drilling working space required by the working platform is 2-3 m;
4) excavating a pedestrian ventilation patio in the footwall surrounding rock on one side of the middle section transportation roadway which is directly opposite to the ore removal roadway to be communicated with the upper middle section air return roadway, excavating layered communication roads in the pedestrian ventilation patio every 3-8 meters in the direction vertical to the studs to reach the footwall ore rock contact surface, and dividing the studs into a plurality of layers in the vertical direction;
5) when layered stope operation is carried out each time, operating personnel enter the stope through the pedestrian ventilation patio and the layered communication channel, upward parallel blast holes are drilled, and the depth of the upward parallel blast holes required by rock drilling is appropriate to the layered height of the stud, namely 3-8 m; then, carrying out charging, line blasting and ventilation operation step by step, and then operating a scraper in a bottom ore removal roadway to carry out local ore removal operation, wherein the ore amount discharged each time accounts for 30-38% of the total amount of the caving ore; in order to facilitate the drilling and blasting operation of personnel on the shrinkage pile, the top prying and leveling operation should be carried out after the partial ore drawing;
6) adopting the mode from bottom to top to circulate the operations of drilling, blasting, ventilating, local ore drawing and prying the top and flat field in each layered stope in turn until the whole stud is completely mined, and then using a scraper to carry all the ores in the reserved stud to a chute arranged on one side of a ore body footwall middle section transportation roadway;
7) after ore removal is finished, the filling retaining wall is used for sealing the ore removal roadway and the lower inlet of the pedestrian ventilation raise, and then the filling operation link of the left space after the stud mining can be implemented.
Furthermore, in the pedestrian ventilation sky well, the layered communication channels are preferably tunneled every 3-6 meters in the direction perpendicular to the stud.
Furthermore, the section specification of the ore removal roadway is 3.5m multiplied by 3.5 m-4.5 m multiplied by 4.5 m; the specification of the cut patio is a rectangular section with the side length of 1.2-2 m, and the specification of the pedestrian ventilation patio is a rectangular section with the side length of 1.2-1.8 m; the side length of the layered connection channel is 1-1.5 m of a rectangular cross section.
Furthermore, the height of the horn-mouth-shaped bottom structure is 3-8 m.
By adopting the technical scheme, the stoping method of the underground mine goaf left stud achieves the purposes of realizing wind flow communication of a stope, improving the ore recovery rate, reducing the ore dilution rate, reducing the mining process quantity, avoiding overlarge exposed area of the goaf and improving the working environment. The concrete positive effects are as follows:
(1) only partial ore pillars are reserved above two sides of the ore removal roadway at the bottom of the stud for forming a bottom structure, so that the stud recovery rate is more than 95 percent, and stud mineral resources are greatly recovered.
(2) According to the stability of the ore rock and the filling body, the layered rock drilling height can be randomly changed, so that the mining blasting disturbance is reduced, the deformation of the surrounding rock is controlled, the mixing rate of waste rock and the dilution rate of ore are reduced, and the exposure scale of a stope is controlled.
(3) A cutting raise is arranged on the upper disc of the stud to penetrate through an upper middle section air return roadway, a pedestrian ventilation raise is arranged on the lower disc of the stud, fresh air flow enters a working face through the pedestrian ventilation raise and a layered connecting channel in each rock drilling and blasting operation link, and dirty air is discharged through the cutting raise after a stope is washed, so that circulating penetrating air flow is formed, the ventilation condition of the working face is improved, and a good operation environment is favorably built.
(4) The mining and cutting workload required by rock drilling tunnels and carrying rock drilling equipment is not required to be arranged in each layer, and a large amount of ore is uniformly drawn after all the layers are stoped, so that the mining and cutting workload can be obviously reduced and the production efficiency of a stope can be improved.
(5) When the filling is completed by the pillar mining, only the closed retaining wall needs to be built at the bottom of the ore removal roadway and the bottom entrance of the pedestrian ventilation patio, so that the consumption of materials for constructing and filling the retaining wall is reduced, the filling cost is reduced, and the filling efficiency is improved.
Drawings
FIG. 1 is a front view of a stoping method of a goaf left-over stud of an underground mine;
FIG. 2 is a view taken along line A-A of FIG. 1;
FIG. 3 is a view taken along line B-B of FIG. 1;
FIG. 4 is a view taken along line C-C of FIG. 3;
FIG. 5 is a front view of a stoping method of an underground mine goaf remaining stud in accordance with the present invention in the arrangement of a bottom structure;
FIG. 6 is a front view of a method of stoping a goaf remnant stud in an underground mine after the formation of a bottom structure.
The reference signs are: 1-middle section transportation roadway; 2-ore removal roadway; 3-pedestrian ventilation patio; 4-pass shaft; 5-a filling body; 6-pillar mining; 7-ore caving; 8-hanging the ore rock contact surface; 9-layered contact road; 10-a working platform; 11-upward parallel blast holes; 12-cutting the raise; 13-footwall surrounding rock; 14-a bottom structure; 15-rock drilling work space; 16-studs; 17-footwall rock contact surface; 18-fan-shaped medium-length hole.
Detailed Description
In order to better describe the invention, the stoping method of the underground mine goaf remaining stud of the invention is further described in detail with reference to the accompanying drawings.
As shown in fig. 1, the stoping method of the underground mine goaf left-over stud according to the present invention is shown in a front view and is combined with fig. 2, fig. 3, fig. 4, fig. 5 and fig. 6, the stoping method of the underground mine goaf left-over stud according to the present invention is implemented by the following steps, wherein a stud 16 is arranged in an ore body, ore rooms are arranged on two sides of the stud 16, and a middle transportation roadway 1 is arranged on a lower tray of the ore body:
1) when stoping of the chamber is finished and a filling body 5 formed by cementing and filling tailings reaches 1.5MPa, a three-core arch ore removal roadway 2 with the specification of 3.5m multiplied by 3.5m is tunneled into a stud 16 at one side of a middle section haulage roadway 1 along the direction vertical to the trend of the ore body to reach the hanging wall rock contact surface 8 of the ore body;
2) a cutting raise 12 with the specification of 1.5m multiplied by 1.5m is tunneled upwards along the hanging wall ore rock contact surface 8 at the end part of the ore removal roadway 2, and the cutting raise 12 penetrates through the upper middle section return air roadway and is used as a return air channel of an initial rock drilling blasting free surface and later layered stope operation;
3) in the stud 16, a fan-shaped medium-length hole 18 is drilled upwards along the top of the ore removal roadway 2, the included angle alpha between the fan-shaped medium-length holes 18 on the two sides and the horizontal direction is between 45 and 60 degrees, and the depth of the medium-length hole is preferably 2 to 5 m; taking the cutting raise 12 and the ore removal roadway 2 as free surfaces, forming a bell mouth-shaped bottom structure 14 after row-by-row blasting, discharging part of ores by adopting a scraper, temporarily reserving the rest ores in a space of a stud 16 as a working platform 10 for continuous upward mining, and keeping the height of a rock drilling working space required by the working platform 10 to be 2-3 m;
4) excavating a layered connecting channel 9 with the specification of 1.2m multiplied by 1.8m in the direction perpendicular to the stud 16 in the pedestrian ventilation patio 3 every 3-8 m to reach the contact surface 17 of the lower wall rock, and dividing the stud 16 into a plurality of layers in the vertical direction;
5) when the layered stope is operated at each time, an operator enters the stope through the pedestrian ventilation patio 3 and the layered communication channel 9, upward parallel blast holes 11 are drilled, and the depth of the upward parallel blast holes 11 required by rock drilling is appropriate to the layered height of the studs 16, and is about 3-8 m. Then, carrying out charging, connecting line blasting and ventilating operation links step by step, and then operating a scraper in the bottom ore removal roadway 2 to carry out local ore removal operation, wherein the ore amount discharged each time accounts for 30-38% of the total amount of the caving ore 7; carrying out prying and leveling operation after local ore drawing;
6) the method comprises the steps of circularly drilling, blasting, ventilating, partially drawing ore and prying a top flat field in each layered stope from bottom to top in sequence until all the studs 16 are completely mined, and shoveling and conveying all the remaining ores in the studs 16 to a chute 4 arranged on one side of a ore body footwall middle section transportation roadway 1 by using a scraper;
7) after ore removal is finished, the filling retaining wall is used for sealing the lower inlets of the ore removal roadway 2 and the pedestrian ventilation patio 3, and then the filling operation link of the left space after the extraction of the studs 16 can be implemented.
As shown in the figure 1 and combined with the figure 2, the stoping method for the underground mine goaf remaining studs only reserves partial ore pillars 6 above two sides of the ore removal roadway 2 at the bottom of the stud 16 to form a bottom structure 14, and the stoping rate of the stud 16 can be more than 95%.
The invention adopts a bottom-up layered stoping mode, only part of ore pillars 6 are reserved when the bottom structure 14 is arranged, and the ore stoping rate is greatly improved; the layering height can be seen, the stability of the ore rocks and the filling body 5 can be changed randomly, the damage to the surrounding rocks and the filling body 5 can be effectively slowed down, and the ore dilution rate is reduced; the upper plate cutting raise 12 is communicated with the upper middle section return air roadway, so that air flow circulation is realized, and the environment of a working face is improved.