Stage mining method, mining method mining column mining

First, the actual and program

When using the stage mining method and the mining method, the ratio of the reserves of the ore column varies greatly with the thickness of the ore body. The reserves of thin and extremely thin and steeply inclined veins are generally not more than 5.10%, and can reach 30% to 60% in thick and extremely thick ore bodies. In the latter case, pillar recovery should be the focus of research.

Shrinkage Method by mining the thin and steeply inclined thin veins, mostly the mining of precious metals, mostly without leaving studs, leaving only some roof pillar or column; some shallow, ore and rock is solid, small press No pillars are left in the mine or section. If there is a pillar, except for the need to control the ground pressure and the treatment of the empty area, some low-grade pillars are not taken, and the rest should pay attention to the recovery. The pillars and organics do not need to dig the quasi-roadway, and directly drill the rock from the stage and the column. After the mine is vented, the top and bottom columns should be harvested at the same time. The column is generally detonated before the top and bottom columns. Because the ore is stable, the top and bottom will not fall off due to the column blasting, or there will be overburden in the upper stage. This is especially true (Figure 1). Because it is necessary to drill the top hole of the tunnel in the upper stage of the transportation lane, it is better to drill the hole in the mine before the mine is released.

Figure 1 Back to the mining column when the mine stays in the mine

A-recovering the top bottom column; b-recovering the column

The ore-preserving method and the stage mining method are used to recover the ore pillars of the ore body which is steeply inclined above the medium thickness or the gently inclined and extremely thick ore. Under the condition of the open mine, the main blasting is used for large-scale blasting, that is, the deep hole (very little drug room) is used for blasting. , the pillars are collapsed to the open-pit mine, and the mines are discharged from the mine roadway at the bottom of the ore block under the open field or the overburden rock. According to the need, one blast can collapse the pillars of one or several ore blocks, and sometimes the pillars corresponding to the ore blocks in multiple stages collapse once. After the blasting of the pillar, the ore can be discharged under the overburden or the open field.

When the ore is discharged under the overburden, the overburden rock is formed by natural or forced collapse of the surrounding rock, and its thickness is generally not less than 20m. When the upper empty area is high, the height of the inter-column should be appropriately thickened. Compared with the open field under the open field, it can better eliminate hidden dangers in the empty area, ease the stress concentration, and facilitate the management of ground pressure. These advantages are more obvious when the caving reaches the surface, but the loss of the ore loss is large, sometimes up to 40~60. %, the topping fee is also required when forcing the top (Figure 2).

Figure 2: Falling overburden and back to the mining column

1—horizontal deep hole; 2—vertical fan-shaped medium-deep hole; 3—beam-shaped medium-deep hole; 4—agglomerate overburden

When the ore, especially the surrounding rock, is very stable, and the pillar collapses to maintain a large and stable area, the mine can be discharged in the open field. This is often the case with the first stage of a mine with a small-scale blind ore body or a large blind ore body (Figure 3). When recovering other stages of thick ore bodies, the following measures can be taken to ensure safety: a certain thickness of ore bedding is reserved according to the height and range of the empty area; a supporting column is left at a certain distance and is not recovered (preferably left in poverty) Mine section), closed through the empty passage. The main advantage of the mine under the open field is that the ore loss is low and can be close to the mine. In some cases, it may be necessary to fill the empty space to maintain the surface as needed.

Figure 3 Empty field back to the mining column

1—top column; 2—bottom column; 3—inter-column; 4—upper mining roadway;

5—Patio; 6—Contact Road; 7, 8—Electric Ramp;

9—windward patio; 10—sliding well; 11—personal well

Whether or not to release ore under the overburden rock depends mainly on the stability of the ore and surrounding rock and the treatment method of the empty area. In actual production, the two can be combined. For example, under the conditions of the stability of the ore, the first interval mining will not contact the caving and overburden in those inter-columns or the top and bottom columns, and the ore will be discharged in the empty field; when the empty ore houses merge to reach the limit exposed area, the remaining ore will be collapsed. Columns, ore deposits under the collapse of overburden, so that mining, domestic and foreign mines are no shortage of successful examples.

Second, picking

The mining lanes required for mining should be shared with the mine as much as possible to reduce the workload and avoid excessively cutting the pillars. The location of the rock tunnel should consider the safety of the operation and the need to arrange the blastholes. When designing and developing a system, it is necessary to create conditions for timely return to the mining column. SHOUWANGFEN copper mining and 500m above the horizontal registration with the pulse, and to protect the transport of Ventilation stage, about 30 to 40% of the amount can not be timely pillar mining; 400m below the level of the use of the veins of Preparatory solution this problem. In 1983, the mine's ore content accounted for only 6.2% of the mine's mining volume, and the pillar recovery conditions were improved.

Third, falling mine

The large blasting method can be divided into deep hole (including medium and deep hole) blasting and chamber blasting. The blasting of the chamber is rarely used, because it is used for pillar mining, and its shortcomings are more prominent: the safety of the chamber is particularly poor in the pillars, especially in the top and bottom columns, and it is difficult to control the boundary of the collapse. The ore block is large, which leads to difficulties in mining and loss of depletion. In a special case, it can only be used as an emergency measure and an auxiliary method. For example, because the ground pressure is large, it is necessary to recover the pillar in advance but not only to drill the blasthole; some parts cannot arrange the blasthole; the rock drilling roadway and the blasthole are Destruction can not be blasted, etc. The deep holes below the level of the top and bottom columns of the mining top are mostly horizontal fan-shaped or bundle-shaped arrangements. The number of rock-dwelling chambers depends on the thickness of the ore body, but generally one is placed between the column and the lower plate. The contact line is not only safe, but also facilitates drilling the blasthole parallel to the lower wire contact line to reduce the loss of the lower plate. When the ore is very stable, the horizontal fan-shaped hole collapsed top column can also be drilled in the rock chamber at the contact line between the middle and lower plates of the top column. The above part of the secondary crushing level of the bottom column is generally recovered from the electric tunnel drilling to the fan-shaped or beam-shaped blasthole; if there is difficulty in the construction of the ramp, the rock chamber can be arranged at the end of the ramp to the peach-shaped pillar. Parallel blastholes are drilled with a triangular pillar between the ramps. The column is extracted by the upward (or downward) fan-shaped (or bundle) blasthole. The arrangement of the blasthole and the rock-filled roadway depends on the thickness of the ore body, the height of the stage, and the location of the original roadway.

A large number of caving methods return a large amount of blasting explosives to the mining column, and attention should be paid to the impact of small earthquakes on underground and surface buildings.

The high output rate of large blocks is a major problem for a large number of caving methods to return to the mining column, which not only reduces the strength of the ore, but also increases the loss and depletion of the ore. The reason for the high block rate is that the pillars are not flat, the outline is unclear, and it is difficult to arrange the blastholes as required; in the mine blasting dynamics or mine pressure, the pillars are deformed and destroyed, and some parts of the pillars cannot be arranged with blastholes. Or the blasthole is scrapped; the construction quality of the blasthole is low, the depth and direction are not satisfactory, and so on. To this end, we should return to the mining column in time to maintain the integrity of the pillars and blastholes; carefully arrange the rock tunnels in the pillars to facilitate the uniform arrangement of the blastholes; carefully drill the rocks, strictly check the quality of the blastholes; And the construction quality, to ensure the design specifications of the pillar, not super-explosive, not subject to blasting damage. When the Rio Tinto copper mine in Spain uses the large hole empty field method mining room, in order not to damage the pillar, the blast hole of the mine boundary is not coupled with the charge, and the explosive is placed in a 102mm corrugated thin-walled plastic pipe. The sand is filled between the pipe wall and the wall of the hole. For the same purpose, a mine in Canada used measures to encrypt adjacent blastholes and uncoupled charges.

Fourth, the mining order

To determine the order and blasting scale of the large blasting method back to the mining column, generally consider the following factors:

(1) The stability of the ore. The stability of the ore is poor, the weak surface of the geological structure is developed, and the mining is not timely, so that the surrounding rock of the upper and lower plates will fall a lot. The serious deformation and destruction of the pillar is difficult to carry out rock blasting according to the requirements, which is the main reason for the extremely low recovery rate of some mines. A mine of No. 5 ore body of 195m has been put on the 195m three-level pillar for a long time to recover. The top pillars mostly fall, the pillars are severely patched, the outline is unclear, and some sections cannot be arranged with blastholes. The recovery rate is only up to 19%. In the Tongmin copper mine, the pillars of several mining sites were previously collected once, because the roof was severely degraded, the blasthole was deformed, and the recovery rate dropped to 26.2%. Experience has shown that the mining sequence and blasting scale of the pillar should be compatible with the stability of the rock; the pillars should be recovered in time, and the pillars will be harvested without damage to the pillars and the surrounding rock of the upper and lower plates will not produce large-scale fragments. The key to greatly reducing depletion and loss. Due to this measure, the Huitongshan Copper Mine has a mine failure rate and a depletion rate of only 9.1% and 5.6% for the seven ore pillars (254,000 tons).

(2) Minimize the contact surface of the collapsed ore and reduce the mixing opportunities of the ore. When the ore body is not long, there are few ore blocks arranged in the stage, and the quasi-external mining time can be used to return to the mining column immediately after the mining house is finished. This is especially true when the rock is stable. In the opposite case, the pillars of several ore blocks can be recovered at the same time, so that the total contact surface of the ore is reduced. A number of pillars have been formed. Due to the deformation and rupture of the large pillars due to the ground pressure, the secondary mining will further sub-synchronize the pillars of the delayed mining, and should also be harvested at the same time.

In the same stage, the column and the top and bottom columns are harvested at the same time, and the column should be detonated in advance. When multiple ore blocks are harvested at the same time, all the intermediate columns in the middle shall be collapsed first, and the sub-column shall be adjacent to the inter-column and the top-bottom column of the collapsed area, and finally the sequence of surrounding rock shall be collapsed.

Try to make the ore mine in the empty field. Under the condition that the ore rock is sufficiently stable, some of the columns may be extracted according to the specific conditions, or the top column (or even the lower part of the bottom column) may be firstly extracted, or the top and bottom columns may be extracted to connect the upper and lower empty mines in the uncapped mine. The ore is released under the cover of the column, and then the remaining pillars and surrounding rocks are collapsed.

In general, several stages should be avoided for the coexistence of the pillars corresponding to the ore blocks. If it has been formed for historical reasons, it should be handled separately. When the surrounding rock collapses and the surrounding rock is easy to collapse, and the inclination of the ore body is slower, the corresponding stages of the same recovery will inevitably cause a lot of loss and depletion. Unless the ground pressure is large, these columns must be collapsed at the same time. Generally, the swindlers should be picked up in stages. In return, when the surrounding rock is very stable and the inclination angle is very steep, the mining is combined once, and the blasting sequence is used first and then the upper part, and the last stage of the pillar is temporarily formed to form an empty field.

(3) Other factors. Such as: the maximum amount of blasting explosives allowed to protect the surface, the wells and related facilities; the annual output of the mine; the length of the stage; the mode of sampling in the stage; the proportion of mining and mining of the mine.

Five, mining

Improving the bottom structure and mining work is an important part of reducing losses and depleting. A discharge funnel should be placed under the column. The ore-mining structure of the mine should meet the requirements of mining pillars. When using the caving method to return to the mining column, the mining structure and parameters of the mine should also be selected according to the caving method; the lowering funnel should be arranged when the inclination of the ore body is less than 70°; the spacing of the small funnel should be appropriately adjusted under the condition of ensuring the strength of the bottom column; The support of the mine roadway should be properly strengthened in consideration of the large number of large pillars during the recovery of the pillars; the ore at the inter-column site is relatively concentrated, and the ore should be preferentially released to reduce the side depletion; the ore discharge should be delayed immediately after the caving zone When using self-equipment to mine, the “dead belt” on the opposite side of the ore discharge port is very large, and the mine room is released to reduce the side depletion; the ore discharge should be delayed immediately after the caving area; when the mine is used for mining, the ore discharge port is used. The contralateral "dead belt" is very large. The mine ore is released to make the ore eyebrow line wear and move outward. When the mining column is returned to the mining column, the release angle of the ore is increased under the overburden rock, and the "dead belt" mineral quantity is greatly increased. Column recovery is too low. Figure 4 is two solutions. Among them, a is to dig the roadway on the opposite side of the ore discharge. After the blasting of the pillar, the “dead belt” ore is recovered by the end of the roadway. This measure can increase the recovery rate by 15.9%. b indicates the use of the swimming type ore discharge. When returning to the mining room, the ore discharge port is located in the mine house. After the mine column collapses, the ore discharge port gradually retreats beyond the boundary of the mine with the ore discharge. In comparison, the latter approach is simpler.

Figure 4 Measures to reduce the loss of “dead band” ore during the discharge of the scraper

A-open special roadway recycling; b-recovery with swimming mine

1—excavation roadway; 2—extraction and veining; 3—ore;

4—rock; 5—dedicated recovery roadway; 6—blast hole

Sixth, evaluation

The large blasting method back to the mining column has a series of advantages such as high mining strength, simple process, high efficiency and low cost. Depletion and loss indicators vary widely in different situations. The ore body is steep and steep, the ore is stable, and the mining is timely, basically releasing the ore under the empty field. The various technical measures are appropriate, and the loss and depletion are not large. On the contrary, the dip angle is slow, the stability of the ore is poor, and the mining is not long-term. When the pressure is large, the mining sequence is disordered under the caving and overburden. If the techniques such as collapse and ore are improperly applied, the loss and depletion are high, and the loss rate can reach 50% to 60% or higher. To analyze the actual situation, take corresponding measures to reduce the loss and depletion of ore.Control Valve, Flow Control Valve, Hydraulic Control Valve, Proportional Directional Control Valve

Some mines use the large blasting method to return to the mining column as shown in Table 1.

Table 1 Some mines use large blasting method to recover the pillars of open-pit mines

Mine, mine section	Mining geological conditions					Mining method
	inclination (°)	thickness (m)	Surrounding rock	Lower wall rock	ore
Tongguanshan Copper Mine, Old Temple Base, a Taihou Body-55~-135 Pillar	60～72	13~15	Marble, stable	Skarn, stable	Magnetic iron ore containing copper quartzite, stable	Retaining method, stage mining method
35m positive and negative 22nd pillar of Xiaotongguanshan Copper Mine	60	twenty three	Flash feldspar , stable	Shale shale , stable	Copper-bearing skarn, stable	Filling method
Shouwangfen Copper Mine 011,0101 pillar	70	15	stable	stable	Iron ore, stable	Stage mining method
1618 ore body of Beishankeng, Huatong Copper Mine	65~75	12	Dolomitic marble , solid	Granite , stable	Copper-bearing skarn, copper-bearing magnetite, stable	Retaining method
Huatong Copper Mine 1673 ore body	Sharp tilt	18	Ibid.	Ibid.	Copper-bearing skarn	Retaining method
Jinling Iron Mine	50	6 to 8 to 15~30	Limestone, f=8	Diorite , stable	Magnetite, medium stability	Sectional rock drilling stage mining method
The pillar of the No. 10 and No. 11 ore blocks of the 4th stage of the Tongmin Copper Mine	55-65	15~17	Falling snow dolomite , stable	Due to the purple layer of the people, the stability is poor	Copper mine, stable	Ibid.
Inuit copper mine monkey jumping rock 2-5 pillar	60～75	4~27	Ibid.	Ibid.	Ibid.	Ibid.
Dongchuan Copper Mine	80～85	8~12	Conglomerate, stable	Incumbent purple sandstone , stable	Incumbent purple sandstone, stable	Ibid.
The Dongchuan Copper Mine falls into the snow-scarred southern section of the 3rd and 4th stages of 9 ore pillars	85～88	17	Sandy slate	Iron slate	Iron slate	Ibid.
Yangjiazhangzi Copper Mine No. 5 ore body - 230 stage 3~6 ore pillar	50~60	6-8	Limestone, medium stability	Limestone, medium stability	Angular rock, skarn-type molybdenite	Empty field method
No. 3 and No. 4 ore body of Fenghuangshan Copper Mine	Sharp tilt	8.9, 10.2	Medium stability	Medium stability	Medium stability	Retaining method
Tianbaoshan lead zinc ore	50～85	4~23	Marble is stable	Stable skarn, diorite	Stable copper-lead-zinc skarn	Retaining method