Coal reserves calculation method
Second, the basic parameters of reserves calculation
(1) Determination of calculated area
According to the general requirements of the reserves calculation and the general formula, the area used to calculate the reserves is as follows:
(1) When the coal seam inclination angle is less than 15. At the time, the horizontal area measured on the contour map of the coal seam floor can be directly used;
(2) When the coal seam inclination is at 15. ~60. At that time, it is necessary to convert the horizontal area measured on the contour map of the coal seam floor into a true area, and the conversion formula is
S = S'/cosa
Where S is the true area; S' is the horizontal area measured on the contour map of the coal floor; a is the coal seam inclination.
(3) When the coal seam inclination angle is greater than 60. It is necessary to convert the area of ​​the façade measured on the coal seam elevation map (ie, the elevation projection map) into the true area. The conversion formula is:
S = S" / sina
Where S is the true area; S" is the area of ​​the facade measured on the projected view of the coal seam elevation; a is the dip angle of the coal seam.
(4) The steeply inclined coal seam has a great change along the strike and tendency, and the upright reverse is frequent. This requires the preparation of the coal seam elevation map, and the area measured on it can be directly used for reserve calculation.
All of the above methods need to measure the area from the drawing, how to determine, the following describes several commonly used methods.
(1) The method of quadrature.
Measuring the area with an accumulator is the most common method used in the calculation of coal reserves. One type of accumulator that has been used in the past is a fixed-pole accumulator with a variable arm, and a fixed-pole accumulator with a fixed arm. Now, there is an accumulator with higher precision and more convenient use. Each type of accumulator has a detailed description, and its principle and instructions for use are not repeated here.
(2) Transparent paper grid method.
First, the transparent paper with the parallel lines of 1cm is placed on the plane pattern to be tested, as shown in Figure 2-8-5. The area of ​​the entire pattern to be measured is equal to the sum of several small trapezoidal areas, each of which is determined by the pattern to be tested. The length of the cross-hatched line is the horizontal line of the trapezoid, and its height is 1. The entire area of ​​the graphic to be measured is actually equal to the sum of the lengths of each horizontal line being intercepted. The length of each horizontal line that is cut can be directly measured by a ruler or measured by a curve meter. The area thus obtained is converted into the actual area according to the scale of the plan.
Figure 2-8-5 Measuring area with curve meter and transparent graph paper
There are two issues to be aware of when using this method:
First, when using a transparent paper to measure the pattern, care must be taken to make the strip width at both ends of the pattern close to or equal to 0.5 cm;
Secondly, in order to check the measurement result, the position of the transparent paper can be changed and measured once, and when the error of the two measured values ​​does not exceed 2%, the average value of the two measurement results is taken.
Figure 2-8-6 Measuring area with transparent grid
(3) Transparent grid method.
A square grid is made of transparent paper or polyester film, and the sides of the square grid are 1 cm long. During the measurement, the grid is hidden on the graph to be measured, and then the number of points in the graph is to be measured. The number of points is multiplied by the area of ​​the grid, and then converted into the actual area according to the scale of the drawing, as shown in Figure 2-8-6. .
In order to be accurate, the two measurements should also be added together and averaged. Pay attention when counting the number of points: where there are not many points outside the line; all the points in the line are counted; only half of the points on the line are counted.
When calculating reserves, the most common method is to use the product to find the area, which is accurate, convenient and fast. If there is no quadrature, you can use the second or third method, which is a relatively simple method, but the speed is slow and the accuracy is not too high.
In the latter two methods, attention should also be paid to checking the expansion and contraction error of the transparent paper or the polyester film.
There are still many calculation methods, each with advantages and disadvantages. The three methods described above can meet the requirements for area.
(2) Thickness of coal seam and its calculation method
1. Calculate the coal seam thickness of coal reserves
The thickness of the coal seam used to calculate the coal reserves is called “the thickness of the coal seam†or “the calculated thickness of the coal seamâ€.
The meaning of coal seams is wide. Not all coal seams can be used for reserve calculation. According to the current specifications, the reserves can be calculated according to the criteria of Table 2-8-19 and Table 2-8-20.
Table 2-8-19 General Area Reserve Calculation Standards
Regardless of the thickness of the coal seam, generally there are stones with different thicknesses and layers. The thickness of the coal seam with the clamp is calculated. The specifications are strictly regulated. The main contents are as follows:
(1) When calculating the thickness of the coal seam, the thickness of the single layer in the coal seam is not more than 0.05m, and the thickness can be calculated by stratification with coal, but the ash and calorific value of the whole layer after the combination should meet the requirements.
(2) When the thickness of the single layer in the coal seam is equal to or greater than the lowest recoverable thickness of the coal seam, the coal stratification separated by the clamp shall be regarded as an independent coal seam, and the reserves shall generally be calculated separately. However, when the clip is only found in individual coal seams, it is not necessary to calculate the layer.
(3) When the thickness of the single layer in the coal seam is less than the lowest recoverable thickness of the coal seam, the coal stratification does not act as an independent coal seam. When the coal stratification thickness is equal to or greater than the thickness of the crucible, the upper and lower coal layers are added together as the thickness.
(4) For complex structural coal seams, if the clamping is relatively stable and the coal stratification can be compared, the thickness of each coal stratification should be calculated according to the above provisions. Otherwise, although the thickness of the single layer of the clamp is sometimes equal to or greater than the lowest recoverable thickness of the coal seam, when the total thickness of the clamp does not exceed 1/2 of the total thickness of the coal seam, the total thickness of each coal layer can be used as the coal seam. The thickness of the use! .
The above is a normative requirement, and it can also be a product of a planned economy, but it is not necessarily the case under market economy conditions. The market economy is the leading role of efficiency. Similarly, the calculation standard of coal also fluctuates with the benefit. Therefore, the standard of the norm can not be regarded as fixed.
2. Determination of coal seam thickness and conversion of true thickness
(1) Method for determining the thickness of coal seams.
The determination of the thickness of the coal seam is divided into two methods: direct measurement and indirect measurement.
O complex structural coal seam refers to a large number of interlayers, but the thickness of the single layer is small, generally less than the lowest recoverable thickness of the coal seam. It is not required to be layered and contrasted in exploration and mining, and can be evaluated according to the variation of the thickness of the whole layer. Coal seam stability of the coal seam.
The direct measurement is to directly measure the thickness of the coal seam from the coal seam exposed by the trench, the tunnel and the rock core of the borehole. The indirect measurement is to determine the thickness of the coal seam from the physical logging data.
Coal seam thickness measurement requirements:
First, the top and bottom of the coal seam must be very clear when directly measured, and the top and bottom must maintain the original characteristics of the bedrock, rather than being artificially loosened or collapsed; it must be measured perpendicular to the top and bottom.
Secondly, using the drilled coal core to determine the coal thickness is divided into two cases. First, the core rate is 100%. At this time, the coal thickness can be directly measured in the core tube. Second, the heart rate is less than 100%, but equal to or greater than According to the regulations, the thickness of the coal seam should be judged according to the lithology, the coal and the depth of the coal and the wear of the coal core, the surrounding coal thickness, and the coal notice.
Third, the use of logging data to determine the thickness of the coal seam must be carried out in accordance with the requirements of the logging procedures officially promulgated by the relevant departments.
(2) Conversion of the true thickness of the coal seam.
Exploration specifications stipulate that when the coal seam inclination is greater than 15. When necessary, the reserves must be calculated using the true thickness of the coal seam. In the calculation of the true thickness of the coal seam, the following simplified calculation formula can be used:
M = M'/cosa
Where M is the true thickness of the coal seam; M' is the pseudo-thickness of the coal seam (drilling thickness); a is the dip angle of the coal seam.
This is an approximation, but the error is within the allowable range and applies to any oblique hole.
3. Determination of average thickness
One of the parameters in the general formula for calculating coal reserves is M (coal thickness), which is generally not determined by a coal spot, but is often determined by several or even more common coal points. The average thickness of the coal seam used for reserves is generally divided into two steps:
(1) Determine which coal points participate in the calculation of the average thickness of the coal seam.
Participation in the calculation of the average thickness of the coal seam is generally a qualified coal spot within the predetermined block range, but sometimes there are special circumstances.
1 Sometimes you can borrow qualified coal points outside the block range
In this case, it is generally seen that there are relatively few coal points in the block section, or the distribution is very uneven, and there is a close coal point outside the block section.
2 The coal seam thickness point can be artificially increased or decreased within the block range.
A. Increase the thickness of the coal seam.
Generally, when there are not too many coal points and uneven distribution, several coal seam thickness points can be added in the part where the coal spots are relatively small. The method is to use the interpolation method or the lowest recoverable boundary line of the coal seam. Take a few points as appropriate.
B. Reduce the coal seam thickness point.
Generally, it is seen that there are many coal spots and the distribution is uneven. When the thickness of the coal seam changes greatly, this method is adopted, that is, the coal spots are appropriately reduced in a dense place.
Whether it is borrowing outside the block, or artificially increasing or decreasing the coal spot, the purpose is to make the calculated average thickness of the coal layer representative in this block, enough to use, and should not be used.
The average thickness of the coal seams of each reserve block is calculated by the method used by those coal seams and must be listed in the attached table for future reference.
(2) Calculation method of average thickness of coal seam.
After determining which coal seam points are involved in the average thickness calculation, the average thickness of the coal seam of the block may be determined by an arithmetic average method or a weighted average method. However, in practice, most of them use the arithmetic averaging method, and the weighted averaging method is rarely used.
The arithmetic mean method is calculated as:
Where M is the arithmetic mean thickness of the block segments; Mp M2,..., M& is the thickness of each coal seam point; n is the number of exploration projects participating in the thickness average.
For extra-thick coal seams, according to the requirements of the specification, the cause should be identified and properly treated. What is a special thick coal seam point is generally understood to be more than three times the thickness of the surrounding coal spot. If there is no doubt about the thickness, if there is no more suitable treatment method, the following method can be used: firstly, the average thickness is calculated by the arithmetic average method, and the average thickness is regarded as the thick thickness of the coal point, and then the block segment is involved. The calculation of the average coal thickness.
(3) Determination of bulk density
The so-called bulk density, that is, the weight of coal in a unit volume. By its intent, it is the weight of a unit volume of coal in its original void fraction, fissure and moisture content.
As can be seen from the general formula for calculating reserves, a small change in the bulk density causes a large change in the reserve data because it is multiplied by a large volume number. This is not to say that the other is not important, but that the weight of coal is more important, and the actual situation is often less important.
The bulk density of coal is mainly determined by the composition and content of ash, the degree of metamorphism of coal, and secondly determined by the structure, structure, coal composition and moisture of coal.
The bulk density of coal should be strictly in accordance with the relevant regulations from the sampling, sample preparation, sampling density to the completion of the entire test work to ensure the accuracy of the bulk weight quality.
In the reserve calculation, the coal capacity is generally calculated to two decimal places.
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