Contour method for calculating coal reserves

Reserve calculation method

(2) Contour method

This method is the area A between the adjacent two contour lines on the base layer of coal contour map, reserves recalculation method, according to different methods seeking area, was divided into two cases:

1. Direct calculation method (Figure 2-8-13)

Figure 2-8-13 Contour map calculation of reserves

That is, according to the known data, the reserves are directly calculated, and the formula is as follows:

Where, Q is the coal reserve between the two contour lines, I is the midline length between the two contour lines, and can be measured by a curve meter or a curved ruler; b is the horizontal projection length (flat distance) between the two contour lines; h is Contour height; m is the average thickness of the coal seam; d is the average bulk density of the coal seam.

This method can meet the needs of the mine design and production department to the maximum extent because of its horizontal calculation and statistical reserves according to the contour line. The calculation method is also simple and the precision is high. Suitable for areas with stable or relatively stable coal seams and with significant structural changes.

2. Average dip angle method

This method is mainly intended to make up for the cumbersome defects in the determination and calculation of coal seam area in the direct calculation method. The true area of ​​the coal seam between two adjacent contour lines is equal to the product of the horizontal projection of the area and the secant of the average dip angle of the coal seam between the two contour lines. The calculated formula after derivation is:

Q = B x secα x M xd

Where, Q is the coal reserve between the two contour lines; B is the horizontal projection area of ​​the coal seam between the two contour lines; α is the average dip angle of the coal seam in the calculation block; M is the average thickness of the coal seam in the calculation block; d To calculate the average bulk density of the coal in the block.

For angles greater than 60. The steeply inclined coal seam, the reserve calculation must be carried out on the coal seam elevation map, and its calculation formula is:

S = B' x cscα,

Then Q = B' x cscα x M xd

B' is the calculated projected area of ​​the coal seam elevation of the block.

An important task of this method is to verify the average inclination of the coal seam between the two contour lines. There are two ways:

(1) The pay-off scale curve method.

According to the scale and contour height of the contour map of the coal seam floor, the horizontal distance between the contour lines is made at a certain angle (generally 1 or 5.), and the curve of the scale is made, as shown in Fig. 2 8-14. Using this map, the corresponding coal seam dip angle can be obtained from the horizontal projection distance between two adjacent contour lines on the coal seam floor contour map.

(2) The residual cut rule method.

Each coal seam floor contour map has a defined scale and contour. The smaller the dip angle of the coal seam, the larger the horizontal projection distance between the contour lines, and there is a trigonometric function relationship between the three (see Figure 2-8-15):

艮P b = hx ctgα

Where h is fixed on the floor contour map of a coal seam, which is equivalent to the constant of a certain function, and b varies with the change of α, which is a change of cotangent relationship, using this relationship α starts to decrease from the largest (90.), and b gradually grows from small to large, thus obtaining a series of data, and marking it on a ruler becomes the cotangent ruler as shown in Fig. 2-8-16. Using this ruler to directly measure the distance between two adjacent contour lines on the contour map of the coal seam floor, the inclination of the coal seam can be directly read from the ruler. Not only can the true dip (maximum) be read, but the apparent dip in all directions can be read.

Figure 2-8-15 Schematic diagram of the method of drawing the residual cut ruler

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