Application of Upward Horizontal Layered Cementation Filling Method in Duoda Lead-Zinc Mine

Duda lead zinc mine located in the southern Pakistani province of Las way to serve Beira region Kan Lajie valley, an altitude of about 550m, south gradually reduce connected to the Indus plains. In the mining area, the Clarion River flows from the north. The river is a perennial river and is not allowed to fall.
The structure of the mining area is relatively developed. Due to the east-west extrusion, the formation bends and deforms to form folds, and the near-south-north direction reverse fracture is more developed.

The mineralized zone is strictly controlled by structure. The ore body is located in the two-wing asymmetric syncline stratum near the north-south direction. The extension length of the mineralized body is 1100m in the north-south direction, 200-400m in the east-west direction, and 10~40m in thickness. The buried depth is 75 to 1000 m. It is spatially northward with a side angle of 30°. The occurrence relation, the ore is divided into three spatially layered mineralization, i.e. from the disc to the lower disc are mineralized breccia, yellow iron and zinc ore belt band. The mudstone and argillaceous limestone of the Plat3 formation are developed on the upper part of the ore body, and the lower part is a braided limestone and mudstone with rhythmic interlaced bedding.
The Duoda lead-zinc deposit has poor ore conditions, especially the No. 1 main ore body with higher grade, which occurs in the syncline structure, and some ore bodies are present in the syncline core, and the ore body is mudstone. And argillaceous limestone, thickness 1 ~ 3m, the lower plate is carbonate and decalcified shale , the joints of mineral rock development, f = 4 ~ 8, poor stability, the surrounding rock is more likely to collapse with the ore body phenomenon.
1 Mining method Duda lead-zinc ore body belongs to ore body with complex thickness and grade change. The shape of ore body is complex, and the boundaries between rich ore body and lean ore body are blurred, and the depletion and loss are difficult to control. The ore is a high-sulfur ore. Easy to oxidize, high temperature and high sulfur in the stope, good ventilation is required to ensure safety and suitable working environment; the surrounding rock is interbedded with limestone and mudstone, the surrounding rock and ore are not stable, and are subject to east-west direction. The influence of horizontal principal stress, the stope collapse is serious; the east wing ore body is scattered, and the occurrence is slow, and the recovery is difficult. Considering the above characteristics of ore body, rock stability, ground stress control, loss and depletion control, flexibility of mining production arrangement and safety production, it is necessary to solve the problem of stope ventilation, strong mining and strong charging, and reduce the exposure time of the stope. To minimize the loss of losses and ensure economic benefits, it is advisable to use the upward horizontal layered cement filling mining method for recovery (see Figure 1).

The mining body of the mining area adopts the upward horizontal layered cementing filling mining method to not only meet the safety production requirements, but also effectively prevent the surface collapse, and at the same time, the tailings can be filled into the ground to reduce environmental pollution.
1.1 The structure parameters of the stope are based on the characteristics of the occurrence and change of the ore body in the mining area. The mining method is adopted by the upward horizontal layered cementation filling mining method. The stope is arranged along the ore body, with a length of 50m and a reserve of 6m. Permanent pillar, the width of which is the thickness of the ore body, the height of the stope is 60m (or the height of the ore body), and the height of the section is 20m. The specific parameters are as follows:
(1) Top column: reserved 3m thick top column;
(2) Bottom column: 7m thick bottom column is reserved, 0.5m thick reinforced concrete floor is constructed on the bottom column, so that the bottom column can be safely recovered in the future;
(3) Stratified height: 2.5m, the height of the first layer is 3.5m, and the height of each layer after filling is 2.5m;
(4) Maximum empty roof height: 4m, each filling height is 2.5m, and the height of the next layer mining working space is reserved for 1.5m.
1.2 Alignment cutting The mining standard is to dig the section roadway by the slope road, and the section roadway is arranged along the ore body direction in the lower part of the ore body. From the sectioned roadway to the stope with a slope of 15% to 20%, one excavation approach is made, and the approach is arranged in the middle of the stope; the bottom section is located in the lower part of the ore body. The lower part of the ore body at the two ends of the roadway is filled with filling, pedestrian and ventilation shafts. The well is connected with the main return airway, returning to the main return air well, and serving as a personnel emergency and filling pipeline installation passage. The mining and mining approach will be layer-by-layer mining with layer-by-layer mining to form a layer-by-layer stopway approach to meet the requirements of each layer of mining access roads. After each section is completed, the self-segmented roadway will be re-excavated. Mine approach.
1.3 Mining Technology Upward horizontal layered cementing filling mining method The main mining process is: mining, mining, support, filling, ventilation.
(1) Falling mine. Rock drilling with the YT28 rock drill. In the stope, the upper cutting groove is firstly drilled, and then the shallow hole horizontal blast hole is used for ore mining. The hole depth is 3.5m, the hole diameter is 43mm, and the minimum resistance line is 0.9-1.2m. It is necessary to strictly control the stratification height and the mining boundary of the mining body. Because the heap (or filling body) is close to the top plate, the ore roof is easy to control and can effectively reduce losses and depletion. The detonation method uses non-conducting detonator to control blasting to reduce the surrounding rock loose circle and prevent damage to the stability of the ore body surrounding rock.
(2) mining. The mining uses 3m3 diesel scraper to enter the stope loading and unloading from the stope of the stope, and transport it to the stophole of the stope or the chute of the mining area. The vibrating and concentrating machine is installed at the lower part of the chute to load the mine.
(3) Support. Personnel and equipment work under the roof, with the exposed area of ​​the stope increasing, the stratification height is increased, and if necessary, the roof and the surrounding rock of the upper and lower plates are reinforced or supported to ensure the safety of personnel and equipment and continuous normal production. Bolt support or shotcrete support can be used. The anchor rod is made of 18mm diameter rebar and has a length of 2.0m. It is anchored by concrete anchoring. The shotcrete has a thickness of 100 mm and the concrete is numbered C25.
(4) Filling. The filling of the stope includes the masonry retaining wall and the erection of the filling pipe. The filling pipe is laid from the filling well to the stope. After the preparation is completed, the filling slurry concentration and the material ratio are determined according to the actual measurement of the goaf and the Duda filling process. The volume of the filling body is calculated to provide a filling slurry.
The upper horizontal stratified cement filling mining method is adopted, and the ore body is mined according to the above process parameters. The average mining volume of each mining site is 45579.17t, and the mining cutting engineering quantity is 3552.25m3, and the cutting ratio is 62.46m3/kt.
1.4 The fresh air flow in the stopway of the stope enters the section roadway from the ramp, and then enters the stope along the exit of the stope. After flushing the working face, the manholes at both ends of the stope are filled into the ventilation well to the return airway. After entering the total return airway, enter the main return air well. The main return air well discharges the dirty wind directly to the surface.
2 Filling process The mine adopts Gobi aggregate + tailings structure flow cementing filling process. The Gobi material is crushed into a Gobi aggregate with a maximum size of ≤20mm and transported to the filling station as a filling aggregate. The tailings of the selected plant have a large amount of mud, and after classification, the coarse-grained tailings are naturally settled and dehydrated as a filling set. material. When filling, the Gobi aggregate and tailings are added to the hopper of the filling preparation system by the forklift. After the metering, the filling aggregate is conveyed to the mixer through the conveying belt, and the cement is conveyed to the mixer through the screw feeder. Stirring is prepared into a filling material that meets the requirements, and is self-flowed to the well through the filling hole, and then flows into the to-be-charged field through the underground filling pipe network for filling.
The filling preparation station is located in front of the mining and selecting office building, and is responsible for preparing the filling slurry; the filling slurry passes through the surface to +300m to fill the underground filling pipeline system. Filled borehole has two, one with a preparation, which is made of bi-metal composite pipe wear, Φ194 × 25mm, an inner diameter of 144mm, a working pressure of 8MPa, to cement slurry; filling the bore with the opening through elbow +300m middle section horizontal filling main line connection.

The horizontal filling main road passes through a section of the roadway and enters the middle section of the +300m vein along the vein transportation lane. It is connected with the +300~+260m filling hole through the elbow. The horizontal filling main pipe is 16Mn steel pipe, Φ160mm×10mm, working pressure is 8MPa, and it is connected by quick joint; the number of filling holes, material, pipe diameter and cementing method of +300～+260m are consistent with the surface-+300m filling drilling. The +300～+260m filling hole is located in the +260m total return airway, and is connected with the +260m horizontal filling main pipe through the elbow. The +260m horizontal filling main road is laid along the total return airway. The material, pipe diameter and connection mode are consistent with the horizontal filling main road of +300m.
When short-circuiting is reserved at the opening of the return airway, when the stope needs to be filled, the 16Mn steel elbow and straight pipe are used in the total return airway to enter the wind well connecting lane for 3~5m, and then the steel short-circuiting method is adopted. The blue is connected to the horizontal filling branch pipe. The horizontal filling branch pipe is made of steel braided composite pipe, DN150, inner diameter 140mm, working pressure 2MPa, flanged connection. The horizontal filling branch pipe is filled into the stope by the pedestrian filling the ventilation shaft through the curved pipe, and the lower mouth is arranged in the middle of the stope, and the hanging height should be higher than the filling height.
Filling sequence of the stope: Filling in the order of mining and mining, the filling of each layer of the mine can be completed after completion of mining. Before filling, do a good job of sealing the goaf, and set up a closed wall at each exit of the stratified horizontal stop. The closed wall is made of woven bagged slag and built in two or three layers. After filling, it needs to be cured for 3-7 days, etc. After the platform solidifies, it can continue to pick up.

Calculation of the ratio and demand of cemented filler: According to the experimental research of filling materials and the actual conditions of filling materials, the designed filling mortar concentration is 0.78, the bulk density of the filling body is 2.10t/m3, and the filling body moisture content is 18%. The amount of each material per cubic meter of filling material is shown in Table 1. The cement strength of 7d can be close to the expected strength.

3 application evaluation
(1) The Duoda lead-zinc mine adopts the upward horizontal layered cementation filling mining method, which effectively controls the surrounding rock pressure problem of unstable rock, easy to collapse and large empty roof height; solves the problem of surface subsidence, which makes The main body opening and closing engineering, the tailings pond and the nearby rivers, which are close to the ore body, are not destroyed, ensuring the safe production of the mine.
(2) Duda lead-zinc mine used to be dry-filled mining. The surrounding rock is difficult to control, resulting in poor mining and high loss rate. The average depletion rate is as high as 30% and the loss rate is 28.5%. After adopting the upward horizontal layered cement filling mining method, the labor efficiency is improved, the loss of ore is reduced, the mining recovery rate is 95%, and the depletion rate is controlled within 10%.
(3) After the Duda lead-zinc mine adopts the upward horizontal layered cementation filling mining method, it can recover the previously retained middle section bottom column and the unrecovered residual ore. This can directly recover 455,000 tons of ore directly. Improve the economic benefits of the mine.
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Article source: Mining Technology; 2017.17(2)

Author: Xu rain; China, China Metallurgical Group Corporation, Beijing 100176

Zhang Dong river; Jiaozuo Coal Industry (Group) Co., Ltd. Xinxiang City of Henan Xinxiang Energy 453 633

Jiao Huajun;School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454000, China
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