Mining method of super-poor magnetite in the mining range of the Laoshan Phosphate Mine

0 Preface

With the improvement of the national economy level, the expansion of the utilization of mineral resources and the advancement of mining technology, it has been considered as a low-grade ore and even surrounding rock in the past mining technical and economic conditions. Generally speaking, most of these potential resources are located in the mining range of the original industrial ore body. Under the current mining technology conditions, after the mining of the lower-side ore body is completed, it is affected by the mining and rock moving belts. The occurrence of caving, fissures and deformation in the range makes it difficult to mine the ore body within the mining range. It is one of the frontier research topics of mining technology to safely and efficiently recover the mineral resources within the mining range.
Fanshan phosphorus ore mine CTâ…  is the typical case of the above situation.

The ore body is Fanshan phosphate exploration in the region by one of the producers discovered three layered over lean magnetic iron ore, better exploitation. However, it occurs in the upper plate of the main ore body of No. II, and it is difficult to recover it later by the mining of the main ore body. The mine successfully recycled this type of ore body by strip-type up-level horizontal layer filling and filling method. This paper describes in detail the application of the above mining method in Lushan Phosphate Mine.
1CTI ore body occurrence conditions
        Through the comprehensive exploration and analysis of the original geological data, the Laoshan Phosphate Mine in Hebei Province discovered three layered super-poor magnetite bodies in the area, all of which existed in the layered ultrabasic pyroxenite belt. The top and bottom plates are all black mica pyroxene or magnetite pyroxenite. The thickness of the ore body does not change much, and the inclination angle is generally ±30°. The mineralization characteristics of ore magmatism are obvious, and mineralization is directly related to lithology. Among them, the CTI ore body is extended by 1800m, the true thickness is 30~50m, with an average of 40.93m; the controlled intrinsic economic resources (332) is 12,241,100 tons, the average grade is P2O53.34%, TFe15.02%, mFe7. 49%, TiO22.36%. The bedding, joints and fissures in the ore and surrounding rock are developed with poor stability.
        2 mining methods
        2.1 Mining method selection
        Principles for the selection of mining methods:
        (1) Personnel equipment is safe for mining operations.
        (2) The ground is not allowed to fall, and the surface must be strictly protected.
        (3) The mining method is required to have a large production capacity and can meet the requirements of mine production capacity.
        (4) The ore grade is relatively low, and the selected mining method should have lower mining and filling costs.
        (5) It can make full use of the development and mining project when mining the lower column and ore body. After the mining of the main ore body on the lower plate side, the selected mining method should be able to make full use of the existing development transportation system, and with the support of the post-harvest filling body of the lower plate, arrange the appropriate mining and cutting project to realize the upper mining body. Recycling.
        Considering the occurrence of CTI ore body and the technical and economic conditions of mining, it is recommended to use the column-type horizontal horizontal stratified filling mining method to recover CTI ore bodies. The mining method divides the ore body into a layered mining from bottom to top, with a layering height of 3 m, and the inter-layer ore body is divided into a 5 m wide mining room and a 2 m wide column. At the time of mining, only the mining room is returned. The goaf is filled with low-ash sand than the tailings. The permanent bar and the filling body are used for geostress management. In actual production, the strip width and the access section can be adjusted according to the stability of the roof. The typical scheme is shown in Figure 1.

        2.2 Mining site division and cutting engineering layout
        The height of the middle section is 45m, the length of the ore block is 60m, and the width is the horizontal thickness of the ore body. Each mine block is equipped with 8 mine houses with a width of 5m and a column width of 2m. A 6m high-bottom column is left between the middle sections, leaving no top pillars. The bottom column of the stope can be used for two layers in the normal mining sequence of the lower middle section, and the remaining 2m is no longer recovered as a permanent loss.
        The main mining and cutting projects include the middle section along the vein transport lane, the section along the vein contact lane, the slip mine, the sectional stopway, the ventilation and drainage patio, and the upper body side mining body recovery passage. Utilize the existing middle section of the upper plate to transport the roadway, and arrange a slippery well and a pedestrian ventilation and drainage patio along the strike every 60m to meet the needs of mining and pedestrians and ventilation, and to segment the main roadway along the vein and the main ore body of the mining industry. The segmentation is shared along the pulse communication lane; the segmentation along the vein communication channel is arranged outside the lower disk of the industrial main ore body, and is connected to the upper and lower middle sections through the slope of the mining area, and is reserved in the inter-column reserved after the industrial main ore body is recovered. Segmented along the vein contact road to the ore body to mine the mining channel on the upper side of the ore body; in the mine room, the ore rock on the upper part of the ore body is constructed with a return air filling platform at a stable position, and the lower part is used as a drainage well, and the upper part is used as a drainage well. Return to the wind, fill the patio, and serve as a safe exit for the stop.
        2.3 mining process
        After the completion of the mining and cutting project, the ore block mining is carried out. The horizontal drilling hole is drilled by drilling the rock drill. The hole depth is 3.8-4.0m, the hole diameter is 45mm, and the blasting adopts the ammonium nitrate granular explosive, the charge of the charge, and the non-electrical detonation. The tube is slightly detonated. Each mine in the first layer of ore blocks is vertically moved from the section of the stopway to the boundary of the stope; in the stope, multiple ore blocks can be recovered at the same time, and several sections in one block can also be used. (mineral house) at the same time mining; the first mining stratification height is 3m, starting from the second layer, the stratification and mining height is 2m; each segment is divided into 6 layers for recovery; after all the inlets or partial approaches in one mining room are finished , you can fill the job.
        The approach is ventilated after the blast is over. The fresh air flow enters the segmented roadway from the slope of the mining area or the wind inlet patio, and then enters the stopway through the segmented roadway through the segmented roadway. The sewage wind fills the patio through the return air, the return airway in the upper middle section, and the return airway in the upper middle section. Finally, the wind tunnel is discharged from the surface, and the ventilation of the working face is mainly through diffusion.
After the end of the ventilation, the mane is discharged and the top pumice is removed. Use anchors for reinforcement when encountering unstable locations. At the same time of support, sprinkle and dust the explosive pile. After ensuring the safety of the operation, the mining operation can be carried out. The 1.5m3 electric scraper is used for the mining, and the blasting ore is loaded into the shovel, and then loaded into the mine by the loading hopper at the bottom of the shovel and transported to the middle section.
        2.4 stope filling
        After the end of the approach, the filling preparation can be completed. First, the outlet of the mine and the communication channel is closed. The filling pipe is placed in the mine room by filling the return air patio, and the plastic filling pipe is placed in the middle of the road. Continuous filling. The height of the mine roof is 3m, and it is filled 2m after the end of the mining work. Filling material beneficiation plant tailing, using 1:12 stope bottom ash sand filling than 1.5m, the top surface layer for an cemented filling 0.5m, the strength of greater than 2MPa, lime sand ratio 1:8 tailings The concentration is 70% to 72%.
        After the last approach in a stratification is completed, the high-level draining well can be closed, the outer exit of the stopway can be closed, and the approach will be filled with the central stopway. After the stratified filling is completed, the stratified charging operation ends, and the entire mining site enters the next stratified charging cycle.
        2.5 Main technical and economic indicators
        The main technical and economic indicators of the upward horizontal stratified column filling mining method are shown in Table 1.

        3 conclusions

(1) According to the mining technical conditions of the CTI ore body of the Lushan Phosphate Mine, the design proposed to adopt the strip-type upward horizontal layered filling mining method for recovery. The mining method divides the ore body into a layered mining from bottom to top, with a layering height of 3 m, and the inter-layer ore body is divided into a 5 m wide mining room and a 2 m wide column. At the time of mining, only the mining room is used and the ground pressure is managed by the column and the filling body.
        (2) Production practice shows that the mining method effectively solves the mining problem of super-poor magnetite in the mining range of the main ore body of the Laoshan Phosphate Mine, with good technical and economic indicators, comprehensive block production capacity of 450t/d, ore loss rate. 23.33%, the depletion rate is 5%, and the ore cost is 54.36 yuan/t.
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