0 Preface

Dadiangou gold ore bodies are generally produced in ductile shear alteration zone central, green clay lithology sericite quartz schist, rock ore boundaries is unclear, as the gradient relationship. Developed by the joint method of Pingyi+blind inclined well. The middle section above 1804m is developed by Pingyi, and the middle section below 1804m is developed by Pingyi+blind inclined well.
The 1# and 3# ore bodies between the 8th and 10.5th lines of the 1885m middle exploration line are produced in the fading ductile shear zone, and the surrounding rock and ore are highly oxidized.
There is a north-south main tectonic belt on line 10.5, which has a shape of 259°∠40°, which has a great influence on the ore body, and there are several secondary structures nearby, which have little impact on the ore body, but The rock is damaged to a large extent, and the rock is severely divided and very broken.
The ore body trend is east-west, tending to the north, and the ore body inclination is generally between 70° and 82°. The height of the ore body is west high and low east, the highest elevation is 1935m, and the lowest elevation is 1885m. At the altitude of 1893m, the ore body develops in a band shape, and at 1900m, the ore body is combined into a plate-like development. The formation of the block is 317°∠76°, and the ore type is mainly altered rock type and quartz vein type gold ore. The production exploration has obtained 57,722t of 122b grade, the metal content is 176.52kg, and the grade is 3.17g/ t, the ore grade is rich and poor. The ore body and the surrounding rock of the upper and lower plates are developed and are relatively broken. The rock hardness is f=10~12, the weight is 2.81t/m3, and the looseness coefficient is 1.52. The hydrogeological conditions of the block are simple and the surface is allowed to fall.
Study on the joint mining plan of 1 broken ore vein group
1.1 The problem of mining broken veins
At present, the Dadiangou gold mine is mined by the shallow hole retention method, and there is no filling system. The mining method is used to mine the 1# and 3# ore bodies between the 8 and 10.5 lines of the 1885m mid-section exploration line, which faces more serious problems, mainly including the following points.
(1) The 1# and 3# ore bodies of the mine section are close to the near surface, from the 1885m level to the surface, and the nearest place is only 45m. From the perspective of the pedestrian ventilation patio, the loess has appeared at the elevation of 1907m. The rock is weathered, oxidized severely and broken, and the patio cannot continue to be excavated.
(2) There is a fault fracture zone attached to the upper part of the ore body. When the prospecting is applied to the fault location, the collapse occurs and the width reaches 8m. In addition, the development of small faults in the mine section seriously affects the construction of the roadway and the safe recovery of the stope.
(3) Since the middle section is developed by Pingyi, only one simple road (about 2.2m wide) can transport materials and equipment from the mountain, and large-scale trackless mining equipment cannot reach the middle of the production. Currently, only a small diesel scraper of 0.75m3 can be used for mining.
(4) The 1# and 3# ore bodies are approximately parallel, with low-grade stone in the middle, and the thickness is about 1~3m. Among them, 1# ore body thickness is 3~4m, and 3# ore body is 4~6m, which belongs to steeply inclined medium thick ore body.
(5) According to the results of the engineering geological survey, the rock mass quality of the mine section is poor to very poor. Most roadways require support.
(6) From the mining situation near the stope, the exposed area of ​​the stope should be within 200m2. When one of the veins is mined by shallow hole retention method, the other one will not be able to be safely exploited; if two veins are recovered at the same time, the exposed area of ​​the stope is too large, and large areas will fall and fall, giving life and property to the workers in the stope. Bring threats.

(7) The production in the underground is tight, and the grade of the ore is difficult to increase, which directly affects the economic and financial status of the enterprise. The selection of the plant requires gold ore with high grade ore to increase the overall ore grade of the underground. The high grade ore vein group is in urgent need of mining.
1.2 Comparative analysis of combined mining schemes for broken veins
According to some problems in the mining of broken ore veins in this section, the current status of mining technology of such broken ore deposits at home and abroad shows that, except for the upward horizontal layered filling method, the sublevel caving method is mainly used, and some mines adopt static retention method. And low-segment rock drilling stage empty field method mining.
Based on the current status of production organization management in the middle of 1885m, seven feasible mining schemes are proposed for the high-grade steeply inclined medium-thick deposits, and the seven schemes are compared and analyzed. Among them, schemes 1 and 2 belong to the empty field. Law, Scheme 3 to Scheme 7 belong to the caving method.
(1) Option 1: Low-segment rock drilling empty field method. The method can effectively utilize the existing mining equipment, and the production organization management is relatively convenient; the loss is low; the operator is not working in the goaf, which is safer. The shortcoming is that the production capacity of the stope is small; the amount of mining work is large, and the maintenance cost is high; there is a risk of falling from the roof of the goaf, and it is easy to form an air shock wave, which is harmful to the safety of the workers.
(2) Option 2: Static retention method. The method reduces the falling of the upper and lower plates when the ore is discharged, and the loss is low; the mining process is not changed much, and the production organization and management are simple. The shortcoming is that the production capacity is small at the initial stage; the mining quantity is large, the maintenance cost of the roadway is high; the operation of the operator in the empty field environment is low, and the safety is low; the electric shovel mining requires high continuity of the ore body.
(3) Option 3: Low-level subdivision method. The method of drilling and oreing in the roadway is safe and reliable. Under the cover rock, it can effectively prevent the air shock wave caused by the roof falling in the goaf; it can effectively utilize the existing micro-scraping equipment to mine. The shortcoming is that the amount of mining and cutting engineering is large; the mining area is large, and the loss of two sets of ore in the low-segment mining is large; the production capacity of the stope is low.
(4) Option 4: Sublevel caving without bottom column (along the strike). The method of drilling and oreing in the roadway is safe and reliable; multi-section mining, low quality requirements for medium and deep hole blasting; lower mining requirements, convenient production and organization management, safe and reliable. The shortcoming is that the production capacity of the stope is large; the amount of mining work is large; the losses of the two gangs are large.
(5) Option 5: Sublevel caving without bottom column (vertical direction). The method has multiple ways of mining, and the mining intensity is large; the stone can be partially removed, the ore loss rate is low; the diamond-shaped arrangement of the ore lane is high, the recovery rate is high, and the influence of the structural parameters of the stope on the ore-mining index is reduced. The shortcoming is that the amount of mining and cutting engineering is large; the maintenance cost of the mining engineering is large; and the mining time is long.
(6) Option 6: High-end wall sill-free sublevel caving method. The method has high mining intensity and large production capacity; the amount of mining and cutting engineering is small, the maintenance cost of the roadway is low; the explosion of the explosion pile is good, and the upper sectional working environment is improved; the timing is short. The shortcomings are that the blasting quality is very high, the blasting accident is difficult to handle; the production flexibility is poor, the end wall collapses the ore layer, but the shovel depth is not correspondingly increased; the mining requirements are strict, the gangs and the end loss are Very large; the ore layer is highly lit, and the requirements for mine management are strict.
(7) Scheme 7: Sectional retention ore collapse method. The method has good adaptability to the ore body; the loss is low; when the mine is concentrated, it can be operated by multiple ore-out points, and the production capacity is large; the mine management and production organization requirements are relatively low, safe and reliable. The shortcoming is that the amount of mining and cutting engineering is large; the maintenance cost of the mining engineering is large; the timing of the mining is longer.
The above seven methods of hollow field method (Scheme 1 and Scheme 2) have poor safety due to the need for personnel to carry out mining operations in the open field; the caving method is safe and secure because the mining and mining personnel are all in the roadway. The main technical and economic indicators of the seven methods are shown in Table 1.

It can be seen from Table 1 that in the key indicators such as production capacity, loss depletion, and thousand tons of cutting ratio, the scheme VII----------------------------- Therefore, it is recommended that this scheme be a joint mining scheme for broken veins.
Application of 2-section ore-remaining caving method
2.1 Sectional retention ore caving method
2.1.1 Stope structure and mining cutting

The stope is arranged along the ore body. The length of the stope is 60m, the height of the middle section is 45m, and the section height is 15m. There are 3 sections of mining, which are 1869m section, 1885m section and 1900m section (see Figure 1).

The rock drilling roadway is drilled along the 1# ore body at the 1869m section level, and then the mining road is constructed in the main section of the section below the section, and is connected with the rock drilling road. At the 1885m segment level, the existing rock vein roadway is used as the rock drilling roadway of the segment, and then the mining road is constructed in the main tunnel of the segment and the roadway along the vein. At the 1900m segment level, the sub-pulse is taken through the sub-pulse, and then the rock-drilling lane is constructed in the sub-section. Each segment cutting work starts from the end, and the 1900m segment cutting groove is arranged in 8 lines, and the 1885m segment and the 1900m segment cutting groove are arranged in 10 lines, depending on the prospecting situation.
2.1.2 Mining field recovery technology
The mining process includes rock drilling and blasting of medium and deep hole drilling rigs and mining of small scrapers. The medium-deep hole rock drilling is carried out with the YGZ-90 rock drill for medium-deep hole construction. The hole diameter is generally 60mm. In the rock drilling tunnel, the fan-shaped medium-deep hole is drilled, and the medium-deep hole row spacing is generally 1.4-1.6m. The bottom distance of the hole is about 2.4 to 2.6 m. The explosive is a bulk ammonium nitrate explosive, which is charged with a BQF100 charger. The differential interval is detonated, the interval is 25 to 38 ms, and the detonation uses a non-conducting squib.
Stope cutting: parallel deep holes are arranged in the cutting cross-section, and the end of the trough is cut by the cutting patio; in the middle of the deep hole, it is difficult to realize the groove, and the trough is used to ensure the two safety. Export.
Rock drilling and blasting: drilling the fan-shaped medium-deep hole in the rock drilling roadway, using the cutting groove as the free surface for blasting, the first blasting can blast 5~6 rows, and then the blasting is the free surface for the blasting, each time 2 to 3 rows of blasting, the direct roof of the ore body collapses freely as the exposed area of ​​the stope increases.
Mining in the stope: The level of mining is 1885, 1900, 1869m, of which 1885m is the main concentration of ore. In principle, only 1 part of the ore (30% to 50%) is released from the 1885, 1900, and 1869m rock-drilling roads, and the loose ore is removed. Most of the ore remains in the stope, and all chisels are to be removed in 1885 and 1900m. After the blasting of the rock road is completed, the ore above 1885m level is released from the 1885m section of the ore approach; the 1869m section ore is released from the 1869m section of the ore out route.
The mining equipment uses the 1.0m3 scraper currently used underground.
The 1900m horizontal ore is discharged to the 10-line slide through the 1900m horizontal chute contact road (the original 10-line prospecting patio, the bottom is connected with the middle section of 1869m); the 1885m horizontal ore is lowered to the 1869m level through the 8-line slip mine. 1869m 1869m into the segment and a lower level of mineral ore from the mine will be discharged through the slip level 1804m, 1650m and transported to the middle of the tricycle using # 2 mine concentration slip, ultimately pulled from the motor vehicle to the surface beneficiation plant.
2.1.3 Stope ventilation
The pillarless section of the pillarless ore-retaining method is the outflow of the single-headway, which is difficult to ventilate. It uses mechanical forced ventilation. In the rock-drilling lane, the local fan and the air duct are installed, and the press-in ventilation is adopted to dilute the single-headway. Dust and harmful gases, press the wind into the adjacent return airway or return air patio.
2.2 Field application of sectioned ore-remaining caving method
The index of the mining section of the 1885m middle section 8～10.5 line retaining ore caving mining method is: production capacity: 175t/d (one unit); loss rate: 28.5%; depletion rate: 13.0%; Direct cost of mining: 29.1 yuan / t.
Judging from the above indicators, the production capacity of the stope has been greatly improved, which has met the needs of the ore dressing and the selection of the selected products. The loss of depletion is not as prominent as the retention method. However, due to the use of medium-deep hole caving ore, the direct cost of mining has been greatly reduced, by about 37%.
This program has greatly improved safety operations because the workers are not exposed to the empty space environment. From the construction process of the 1900m section cutting patio and the degree of differentiation and fragmentation of the 1900m sublevel caving ore, the closer the surface differentiation is, the more serious the construction is.
According to this, it can be judged that the maximum exposed area of ​​the broken vein group is about 100 m2. Therefore, it is safe and reliable to use the sectioned ore-remaining caving method to mine the broken ore veins.
3 conclusions

Aiming at the technical problems encountered in the mining of the 8～10.5 line broken ore veins in the middle section of the 1885m section of the Dadiangou Gold Mine, the mining technical conditions were analyzed in detail. Considering the existing shortcomings of the shallow hole retention method, this paper Seven sets of mining method schemes were designed. Starting from the advantages and disadvantages of each mining scheme and key technical and economic indicators, the comparative analysis showed that the scheme 7—the sectioned ore-remaining caving method is the best solution for the combined mining of the broken ore vein group. According to the field test situation, the main technical and economic indicators are superior, the production capacity of the stope has been greatly improved, and it meets the needs of the ore-concentrating of the plant; due to the use of medium-deep hole caving ore, the direct cost of mining is greatly reduced, which is reduced by about 37%; Since the workers are not exposed to the empty space environment, the safety work has been greatly improved. In addition, from the construction process of 1900m segmented cutting patio and the degree of differentiation and fragmentation of 1900m sublevel caving ore, the maximum exposed area of ​​the broken ore vein group is about 100m2. It is safe and reliable to use the segmental ore-remaining caving method to exploit the broken vein group. of.
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