Qian than the annual output of copper ore mine two million Greek t, the amount of metal 30000 t. The ore body is located in the Zambia-Congo copper belt [1], one of the three major international copper belts in the world. The mineralization is sedimentary metamorphism, the ore body is argillaceous rock [2], and the geological conditions are poor [3] ]. Affected by geological effects, the ore body and surrounding rock mass are broken, the RQD value is extremely low (10% to 20%), and it is easy to encounter cementation and disintegration. The ore body is moving closer to the east and west, with a length of 1400-2100m, a tendency of south, a dip angle of about 30°, an average true thickness of 7.36m, a thicker thickness in the eastern and central parts of the ore body, and a relatively small thickness in the west, only 3 to 4m. The original method of stratified tailings stratified filling mining method was adopted, and the recovery rate was only about 55%, which not only caused the waste of ore resources, but also the large amount of mining and cutting, which brought huge production and operation pressure to the mine. In order to obtain higher technical and economic indicators of mines and ensure maximum economic benefits on the basis of safety and efficiency, through the field investigation and feasibility study, the paste filling technology was successfully introduced [4].
The paste filling technology is to prepare surface solid waste (tail sand, waste rock, slag, etc.) into a slurry which is not isolated, dehydrated or precipitated, and is pumped to the underground to fill the stope, and the filling concentration is high, and the filling body is filled. The strength increases rapidly [5], which solves the problems of large amount of bleeding under the well, environmental pollution, low filling body strength, low recovery rate, low filling and topping rate, and poor working environment, which represents the development direction of green mining technology [6]. Because of its good economic, environmental and social benefits, rapid development, currently colored, black, charcoal coal fields are widely used [7].
1Upward horizontal approach layered paste filling mining process
1.1 mining process
The roadway is stratified for recovery. After the road is recovered, the direct roof is the broken ore body, and the two gangs are the filling body or the ore body. Under the joint action of horizontal stress and vertical stress, the fractured ore body with a certain span will produce bending deformation. When the stress reaches the critical strength value, the roof ore body buckling will be destroyed.
According to the characteristics of the roadway mining, the beam structure limit stability theory is applied to analyze the width of the ore body (Fig. 1), and the horizontal and vertical stresses are respectively p and q, according to the formula.
Where Ls is the allowable safe width of the ore body, m; h is the height of the section, ie the height of the mining approach, 4m; [σT] is the allowable stress of the rock, MPa; σT is the ultimate tensile strength of the rock, MPa; q is the uniform load of the top plate of the road, MPa; n is the safety factor, take 6. Through calculation, it is recommended that the width of the west ore body approach is controlled at 4 to 6 m.
The thick ore body of the west ore body of the Chambishi copper mine is mainly concentrated in the central and eastern part, with a thickness of 14-30 m. The average grade of the ore is 2.05%, accounting for about 25% of the total resources of the western ore body. In order to effectively recover the ore resources, a two-step recovery scheme is adopted according to the conditions of the ore bodies (Fig. 2).
The middle section of the ore block is 64m high, the section height is 16m, the stope length is 66m, the column width is 3m, and the mining layer is 4m high. According to the thickness of the ore body, the width of the control road is 4~6m, and it is taken back from the upper plate to the lower plate. The approach uses a Boomer281 drilling rig to drill a parallel horizontal hole of 3.4 m in length and 42 mm in diameter, and is loaded with 38 mm emulsion explosive. The blasting ore is poured into the chute through the LH307 type scraper. The mining approach should be strengthened. The joint anchor bolt and the 4.5m long anchor cable are used for joint support. The bolt support specification is 1.2m×1m, and the long anchor cable support specification is 3m×2m. After the upper plate is taken back, the foot is brushed and the paste is filled. After the flexible retaining wall is made, the paste can be filled. After the lower plate is taken back to the position, the top corner is carried out. After the completion, the joint pressure top can be arranged to fill the paste. The approach road adopts a 1:12 lime sand paste paste, and after the filling is completed, it enters the next layer of recovery.
1.2 Paste filling system process
The full tailings paste is filled with three technical aspects, namely tailings thickening, paste preparation and paste delivery. Adding a single consumption of 20 ~ 30g / t flocculant in 25% ~ 40% of the tailings slurry, using a deep cone thickener to settle and concentrate to 66% ~ 68%, pumped through a deep cone bottom pump to the first agitation tank , preliminary mixing with cement, mixing the filling slurry into the secondary stirred tank and then activating and stirring, then preparing a qualified paste with a concentration of 67% to 70%, and filling the hole and underground through the surface of the KOS2180HP plunger pump The inner diameter of 124mm rubber-lined steel pipe is transported to the filling work surface, and the average filling capacity is 65m3/h. The paste filling system flow is shown in Figure 3.
2 Filling body strength accounting and blasting control
According to the "Technical Regulations for the Production of Non-Ferrous Metal Mines", the strength of the cemented backfill of the upward stratified filling mining method shall meet the requirements that the filling body shall be self-supporting and shall not collapse when subjected to blasting vibration, and shall generally not be less than 1 MPa, and at the same time, satisfy The runner's running surface strength is usually 4 to 5 MPa.
In Zambia, cement is not only expensive but also insufficiently supplied, which limits the increase in the amount of paste filling cement to a certain extent. At the same time, the Chambishixi ore body has a tailings of -200 mesh (-74μm) of 70.85% and -400 mesh (-37μm) of 46.98%. The particle size is extremely fine, resulting in a certain ratio of sand to sand. Adjustments to its paste strength growth rate is not large (Table 1). By placing the ore on the surface of the filling body, the scraper can be operated on the pouring surface. The filling body is now verified and checked in the lateral exposure of the self-standing strength, and the blasting disturbance in the adjacent stope production is reduced.
2.1 Filling body self-supporting strength
The filling body self-supporting model is shown in Figure 4. The condition of self-standing is maintained: on the potentially damaging slip surface, the sum of the damage resistance is greater than the power that causes the filling body to destabilize. The instability dynamics generally refer to the gravity of the upper backfill (G1); the failure resistance includes the sliding surface stress (T) on the potential slip surface and the shear slip resistance between the sidewalls of the sliding filler and the surrounding rock (T1). ). which is
Perform mechanical analysis on Figure 4, then
Where L is the length of the filling body, taking 60m; H is the height of the filling body, m; C is the bonding strength of the filling body, taking 0.15MPa; RV is the self-standing strength of the filling body; U is the friction angle of the filling body, taking 30°; k is the lateral pressure coefficient, taking 0.5; U1 is the friction angle of the ore body, taking 26°; C1 is the bonding strength of the ore body, taking 3MPa; α is the collapse angle, α=45°+U/2. Substituting equations (4) to (6) into equation (3),
Calculated RV = 0.36 MPa.
In summary, the ratio of lime sand to 1:12 and the concentration of 67% to 70% can meet the requirements of the self-supporting strength of the filling body.
2.2 Controlled blasting technology
In the two-step approach, the adjacent low-intensity filling body should be adopted, and the segmented differential control blasting technology must be adopted to reduce the damage of the filling body by blasting as much as possible, and to control and reduce the depletion of ore caused by the collapse of the filling body.
The section is formed in two times. The first time, the rock is drilled and blasted according to the small section (shaded part in Fig. 5); the second time is arranged according to the section of the roadway, and the surrounding hole is used to detonate the light burst or the non-blasting method is used to excavate the roadway. boundary.
The depth of the pupil is 3.7m, the auxiliary eye, the second eye, and the bottom of the eye are 3.5m deep. The 38mm emulsified drug roll is used; the molding eye depth is 3.5m, and the 25mm medicine roll is used. When the blasting of the mine pillar is reserved, the method of “multiple eyes and less charge†is adopted. The distance between the blastholes is 550mm, the blasthole is 300mm away from the filling body, and the 25mm medicine roll is used. The discontinuous charge structure is adopted in the hole to minimize the blasting pair. Destruction of the filling body. The Boomer 281 rock drilling rig is designed for rock drilling. The designed blasting capacity is 185.249kg, which is detonated in 6 stages. The blasthole utilization rate is 84%, and the blasting footage is 2.94m. The design of the blasting control of the filling body interface is shown in Figure 6.
By using the filling body interface to control the blasting technology, the damage of the blasting to the filling body is effectively reduced, the integrity of the filling body is improved, and the depletion rate of the mining site is reduced. At the same time, it also plays a positive role in the stability of the stope (Figure 7).
3 implementation effect
From the end of December 2013 to the end of December 2014, the upward-level horizontal stratified paste filling mining method was successfully applied in the western ore body of the Chambishi Copper Mine. The accumulated filling volume was 104,000 m3 and the cement consumption was 3527t. Filling the pavilion up to 60 or so. In 2014, the recovery rate of western ore body was 67.2%, the depletion rate was 8.9%, and the cutting ratio decreased from 180m3/kt to 120m3/kt. Especially for the middle thick body, after adopting the two-step recovery paste filling technology, the recovery rate is 75%-80%, the depletion rate is about 6%, and the cutting ratio is reduced to 90-100m3/kt, which improves the production technology. Operating indicators, extending the service life of mines, and reducing the overall operating costs of mines.
4 Conclusion
Aiming at the thick ore body in the middle part of the west ore body of the Chambishi copper mine, the upper layered approach layered paste filling mining method is applied, and the beam structure limit stability theory is applied to calculate the inlet width of 4~6m; Theoretical calculation of body self-supporting strength, using lime sand ratio 1:12, concentration 67%~70% paste to fill the stope, its strength meets the mining requirements; low-intensity filling body interface control blasting technology, effectively reduce and prevent blasting vibration to fill Body damage plays a positive role in improving the stability of the stope and ensuring the grade of the mine. After the successful application of this method, the technical and economic indicators are greatly improved, and it is safe and reliable, ensuring efficient and continuous production of the mine.
references
[1] Zhang Jinjun, Shi Fawu, Chen Zhimin, et al. Classification and classification support technology for broken ore rock roadway in Chambishi Copper Mine [J]. Modern Mining, 2013 (7): 74-76.
[2] Zhang Donghong, Xiao Bo, Zhang Wei. Zambia sedimentary copper ( -cobalt ) ore and future mining prospects [J]. Geology and Exploration, 2013, 49(3): 577-588.
[3] Zhao Xingguo. Geological characteristics of the Chambishi copper deposit in Zambia [J]. Geology and Exploration, 2010, 46(1): 183-190.
[4] Hu Wenda, Jiao Huazhen, Wang Yuming, et al. Determination of critical concentration of full tail mortar in Chambishi copper mine based on H-B index [J]. Modern Mining, 2013 (5): 17-19.
[5] Wang Hongjiang, Chen Qinrui, Wu Aixiang, et al. Study on the dense characteristics of full tailings and its application in thickener design [J]. Journal of University of Science and Technology Beijing, 2011, 33(6): 676-680.
[6] Ma Danjiang, Wang Yuming, Wu Aixiang, et al. Downward paste filling method for broken hard-to-mine bodies [J]. Metal Mine, 2014 (3): 4-8.
[7] Yang Yaoliang, Deng Daiqiang, Hui Lin, et al. Theoretical analysis of cementing filling of deep tailings in deep and large stope [J]. Mining Research and Development, 2007 (4): 3-4, 20.
Article source: "Modern Mining"; 2016.10;
Author: Li Hui, Zhang Jinjun, hair Shi Wu, Yang Qingping; the color African Minerals Limited;
Wang Yuming ; School of Civil and Environmental Engineering, University of Science and Technology Beijing;
Jiao Huajun ; School of Civil Engineering , Henan Polytechnic University;
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