Discussion on technical transformation of copper mining technology

I. Introduction

The copper mine was built in 1959 and put into production, designed annual ore 300,000 t. Due to the complex geological conditions of the mine, the high ore content of the ore and the complicated mining conditions of the ore body, it has experienced the difficult process of pit mining, open mining and pit mining; the pit mining technology has also used the caving method and filling method. As the mine ages, the mineral resources decrease, the middle section of the mining declines year by year, the deep ore body becomes slower and thinner, and the original mining process is no longer suitable for the mining of this part of the ore body. Therefore, new mining methods must be sought.

Second, the mining area geological and mining technical conditions

The ore body in the mining area is northeast-trending and tends to the southeast. Due to the structural control of ore-forming and igneous rocks, the ore deposit in the whole mining area is divided into three ore sections, namely the main ore section, the Qianshan ore section and the Qianshannan section. The shape of the ore body in the entire mining area is complex, with as many as 117 ore bodies. The main ore bodies are 4 ^# , 5 ^# , 15 ^# , 30 ^# , 29 ^# , 79 ^# , 84 ^#, etc. The length of the ore body along the strike is 50-200 m, the horizontal thickness is 2-80 m, and the inclination angle is 30-60. Ore than small portion of the top plate surrounding rock stability is poor flint, other than pyrite ore zones are other ore roof marble, good stability, f = 8; Surrounding chassis are diorite, f = 3 ~ 5, due to the development of joint fissures, weathering and dehydration in water, poor stability. The ore body can be divided into three types according to the ore composition: copper sulfur type, copper iron type and monosulfur type. Copper-sulfur ore accounts for 66.94% of copper ore reserves, with an average sulfur content of 24.5% and a maximum of 38% to 44%. From the ore structure, it is divided into copper-bearing skarn and copper-bearing magnetite. The crystal fine particles are densely packed, while the pyrite is mostly dense and blocky. Most of them are crystalline particles loose. Output, the ore is easily broken into powder and easily oxidized. The copper content of the ore is 1.62% on average and the ore weight is 3.75t/m ³ . At present, the middle section of the mine production is mainly the middle section of -257m. The middle section is distributed with 4 ^# , 15 ^# , 29 ^# , 30 ^# ore bodies, of which 15 ^# and 29 ^#矿body are extinct in the middle section; 4 ^# and 30 ^# ore body orientation Nearly east and west, the trend is south, the inclination angle is 20°~55°, and the thickness of the ore body is 10~25m, with an average of 15m. In the oblique direction of the ore body, its thickness, inclination and shape are unstable, and it tends to become slower and thinner. According to geological data, the C+D level reserves in the middle of -257m total 1.6 million tons, and the gently inclined and inclined ore reserves are 64 million tons, accounting for 40%. Among the reserves of about 4.122 million tons below the middle of -257m, the proportion of gently inclined and inclined ore reserves will increase significantly.

Third, the mining situation and existing problems

Mine initial production, the former Hill ^# 4, ^# 5 no-ore mining pillar sublevel caving, due to the high sulfur-containing ores, face temperature is generally 35 ℃, up to 50 ~ 60 ℃, blasthole temperature is usually 40 ~50 ° C, up to 120 ° C. Due to the spontaneous combustion of the ore and the self-explosion of the drug pack, it was forced to stop production twice by +21.5m and +15.5m. In order to reduce the loss of depletion and improve the working environment, it was later converted to a small mid-section caving method with a bottom column. However, the sublevel caving method of the bottom column still does not solve the problems of ore spontaneous combustion, self-explosion of the drug pack, SO ₂ gas hazard, and the inability to recover the residual ore during the mining process. In 1965, the mine had to switch to open pit mining.

With the final formation of the open-pit mining realm, the copper mine was transferred to underground mining in 1981. The mining process was changed to a small mid-span empty field and then filled by a filling method. The mining column is first filled with concrete after mining; the rear mining room is filled with tailings after mining. Practice has proved that the mining method uses the filling method to reduce the lean depletion rate by 50%, and the working environment is obviously improved. The working surface temperature is reduced from 35 °C to 20-26 °C, and the medium-depth hole temperature is 40-50. When °C drops to 30 to 40 °C, the SO2 concentration also decreases accordingly. Therefore, the copper mine has been using the law since 1981. However, as the middle section of mining decreases from -40m to -257m, the proportion of gently inclined and inclined ore bodies gradually increases. The single-stage filling method has the following problems:

As the inclination of the ore body becomes slower, the thickness becomes thinner, and the amount of cutting and cutting works increases, and the cutting ratio of thousands tons is as high as 25 m/kt;

The amount of support works has increased. Since the bottom of the ore body is a granitic diorite porphyry, it is easily weathered after exposure and expands into mud when it is exposed to water. In order to ensure the stability of the mining and cutting project, the supporting workload has to be increased, resulting in a driving cost of up to 650.3 yuan/m.

The loss depletion increases. Statistics show that the ore depletion rate is 18.5% and the ore loss rate is 17.04%.

Fourth, the choice and implementation of mining methods

Looking at the history of mining, the mining of inclined and gently inclined medium-thick ore bodies mainly adopts the segmentation empty field method and the room-column method, followed by the filling method and the caving method, and usually adopts the trackless mining to achieve high mechanization. In combination with the actual situation of copper mines, in the current economic benefit landslide and resource reduction, the choice of mining methods for such ore bodies must meet the requirements of “three highs, three lows, two easy ones and one unchanged”. “Three highs” means high production capacity, high mining efficiency and high safety; “three lows” means low mining ratio, low loss and low mining cost; “two easy” means that the mining process is easy to master and construction is simple; “One unchanged” means making full use of the existing medium and deep hole rock drilling equipment in the mine and the mining equipment such as electric shovel and vibrating miner. Through the on-the-spot investigation of the domestic inclined and gently inclined medium-thick ore mines, the mining of inclined and gently inclined medium-thick ore bodies is proposed. It is advisable to use the explosive filling method to segment the empty field and the subsequent filling method. 150 ~ 200t / d, thousand tons of cutting ratio of 5 ~ 10m / kt, ore loss rate of 5% ~ 8%, ore depletion rate of 5% ~ 10%. The method is intended to be carried out in an industrial test in the 30# ore body.

(1) Nugget arrangement and components

In the course of the test, the ore pillars are divided along the ore body, and the pillars on both sides of the mining room and the rear mining room are first. It adopts medium-deep hole rock drilling, section blasting, explosive force mining, and electric field shovel (vibration concentrator) for mining. After the pillars are recovered, they are filled with tailings cement. After mining, the mines are filled with tailings.

The height of the stage is 43m, the height of the middle section is 18m and 25m respectively; the length of the ore block is 28m and 38m, and the width of the nugget is 18~36m, of which the mine is 12~24m and the pillar is 6~12m. The top and bottom columns are not left in the stage, and the artificial or ore columns are left in the sections.

(2) Cutting and cutting engineering arrangement

The bottom structure of the electric raft or the bottom structure of the vibrating ore is used. The former constitutes the ore channel and the electric raft, and the ore is transported by electricity. The latter constitutes the sump and the vibrating ore concentrating chamber, and the vibration concentrating machine mine. The cutting trough is formed by first digging the cutting patio in the direction of the vertical ore body in the central part of the gutterway mine (column), and then cutting the patio as a free surface, using medium-deep hole rock drilling, playing parallel or fan-shaped deep holes, The mining room (column) pulls the cutting groove on both sides, and the pulling groove is completed together with the leakage (ditch).

(3) Recovery

The YGZ-90 drilling rig is equipped with the FJY27B rock drilling rig. The deep hole is drilled in the rock drilling mountain. All the blastholes are finished once and the blasting is carried out in batches. The amount of ore in each blasting can be accommodated in the trench. Prevail. After the explosion, the ore is discharged by electric shovel (vibration concentrator). When the ore block is harvested, the pillars on both sides of the mining room are first filled, and the tail rubber is filled after mining, and then the mining room is filled with tailings after mining.

V. Conclusion

Tilting and gently sloping medium-thick ore bodies are difficult to transport and control the roof due to their ore mining. It is usually regarded as difficult to mine. Finding a safe, reliable and economical mining method is a subject to be further studied. The mining method of sulphur ore bodies is worthy of further study. The adaptation of the one-time filling method of the explosive force transport section in this paper is still to be proved in the industrial test of mining.

references

[1]Zhang Qiang. The current situation and improvement direction of mining methods used in explosive force mining. Proceedings of the 2nd National Youth Mining Conference, 1996.

[2] Mining Mining Editorial Board Manual Manual Volume 4 Beijing: Metallurgy Industry Press, 1991.

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