Applicable conditions for the stage natural collapse mining method

(1) The ore body should have a certain scale and have sufficient horizontal dimensions to ensure the initial collapse and the required bottoming area to maintain normal collapse. The ore body should have a certain mining height, so the steeply inclined thick ore body is an ideal condition, and the extremely thick inclined ore body can also be used by means of arranging the lower plate funnel. The contour of the ore body should be regular.

(2) The collapsibility of ore is the key condition for the adoption of the stage natural collapse method. The ore is required to collapse easily, and most of it can be broken into small to medium blocks, and the cover rock can collapse into large pieces. It is generally required that the ore is jointed, cracked or moderately developed, and the strength of the ore is low. However, the ore is too soft and broken, and the ore roadway in the bottom column is often collapsed due to excessive ground pressure. The maintenance cost is too high. Whether the natural caving method in the selection stage is reasonable or not depends on its economic rationality.

(3) The ore is required to be homogeneous, which includes two aspects: First, the physical and mechanical properties of the ore are required to be relatively uniform. If the soft and hard layers of the ore body alternate, it is prone to incomplete collapse or high bulk yield; The first is that the grade distribution is relatively uniform, and there are fewer inclusions, because the use of this method can not be selected.

(4) Ore non-cohesive and self-igniting.

(5) The surface is allowed to collapse.