(1) The mined mine has been filled

When the mining house is filled, it is widely used by the sublevel caving method or the filling method. (In short, the method used is rather complicated.)

Which method is chosen depends on the mining method used in the mine, as well as the quality of the filling material and filling.

When returning to the mining column by filling method, the mining of the pillar and the mining of the mine can be carried out in the same stage; when using the caving method to return to the mining column, the different effects of the surrounding rock fall should be considered, and the same stage or backward stage of the mining back room Back to the mining column.

However, no matter which mining method is used to go back and forth to the mining column, the top and bottom columns are generally taken first, and the columns are taken later. (refers to the bottom column left in the previous stage and the top column of this stage.)

(2) The mines that have been mined are not filled (opening mines):

Under the condition that the empty area is not filled after the mining house is finished, the large-blasting method is generally used to return to the mining column.

(1) Why do you want to use the big blast method to go back and forth to the mining column?

When the mine is a goaf, the upper and lower rocks of the mine are mainly supported by the pillars. The longer this state persists, the more the surrounding rock of the upper and lower plates is deformed, and the more likely it is to fall. At the same time, the pillar will also be deformed or destroyed.

(2) Mining method

The large blasting method can be used to return to the mining column, which can be divided into three types: shallow blasting, large-hole blasting, deep blasting, and blasting.

1) The shallow hole blasting method is returned to the mining column.

When the upper stage bottom column and the top stage column are recovered, the upper and lower radial or fan-shaped blastholes can be placed in the upper stage transportation lane. The column section can be superficially placed on the patio and in the corridor. After all the blastholes are finished, they are simultaneously blasted, and the ore that has collapsed is borrowed by its own weight and released through the leakage half of this stage.

At the same time as the pillar collapses, the upper part covers the rock and the surrounding rock, which may collapse with it, so it is necessary to do the ore management work.

The shallow hole large blasting method is suitable for ore bodies with relatively thin thickness (thickness not more than 4-6 meters). For example: My Wulong gold mine used this method.

2) Deep hole blasting method is returned to the mining column.

The deep hole blasting method is applied back to the mining column for steeply thick and extremely thick ore bodies. At this time, it has the advantages of large recovery strength, high labor productivity, simple construction process and safe work. Therefore, this method is widely used in China.

According to the drilling equipment capacity, some rock drilling roadways and rock drilling chambers are added to the appropriate places in the pillars, and deep holes are drilled in them. After all the deep holes are finished, the segments are simultaneously blasted. Generally, the bottom column is a fan-shaped deep hole in the upper stage, and the upper column is a fan-shaped deep hole or a medium-deep hole.

In order to reduce the loss and depletion of ore, some mines will pick up the pillars of several ore blocks at the same time. (Including the bottom column of the upper stage, the top column and the inter-column of this stage), another method is to blast in a certain order, that is, the number of different stages of the detonator to control the blasting.

Under normal circumstances, it is the first collapse column, and then the collapse bottom column. In the figure, I - the column: II - top column; III - bottom column. When blasting, I and II can be first blasted and II under the protection of III. Because of the blocking of the upper overburden with III, it cannot be mixed with the falling I and II ore. Only when blasting III, the overburden will fall. It is also possible to ring I first and then II and III. In short, I, II, and III are the first to rang, but they all belong to the blasting range of this big blast. If properly arranged, it can reduce some ore loss depletion.

3) Using the large blasting method to return to the mining column, there are generally two things: one is the high block rate, and the other is the large loss of ore.

i) The reason for the high block rate is:

1 It is difficult to dig the system roadway in the pillar, so the number of rock tunnels is generally insufficient, resulting in insufficient depth of the blasthole and uneven distribution.

2 The actual existence status of the pillar is unclear, and the design does not match the actual situation.

3 The retention time of the pillar is too long, local damage occurs, and the charge is not complete.

Reasons for the depletion of ore losses:

The main reason is that when the pillar collapses, the upper part of the rock collapses directly. During the collapse process, the upper overburden is mixed with the caving ore, which inevitably increases the loss and depletion of the ore.

In addition, there is a loss of the lower plate during the mining process. From the experimental research, it can be known that if the large blasting method is used to return to the mining column, it is only applicable to the ore body inclination angle less than 70°. The application of this method to the mining column should take necessary measures. Used to reduce the loss of ore in the lower plate, such as digging the lower funnel.

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