It is difficult to take coal samples from coal piles. Due to the oxidation and weathering of coal in the surface layer of coal pile and the influence of humidity in the air, the moisture and oxidation degree of coal in the inner layer of coal pile are different from those in the surface layer. Long-term storage of coal piles may also increase foreign minerals in surface coal, thus increasing ash content. Then, due to the effect of segregation, the large coal gangue gathers on the surface and bottom of the pile when it returns to the pile, and gathers finely in the upper layer and center of the pile, which further increases the heterogeneity of coal quality in the pile. In addition, because the coal in the coal yard is always put into storage at the same time, the ash content of the coal put into storage every time is not consistent. This will lead to inconsistent ash content in the coal in the chimney. So how to ensure that the coal samples taken are representative enough? The top coal at the sampling point of 0. 1M should be removed first, and then mined while digging. Generally, the storage site of coal yard is not plentiful, so it is impossible to separate the mines and pile them up in layers during loading and unloading. With the passage of time, the coal quality in the coal pile becomes more and more complicated. In order to make the coal sample represent the overall appearance of the whole coal pile as much as possible, it is necessary to determine the hard sub-sample position in a large area and evenly. The method of determining the position of sub-samples is the method of taking coal samples from coal piles to be introduced below. (1) method: No matter whether the shape is regular or irregular, when taking coal samples, one surface should be selected as the surface. Draw a line 0.5M from the bottom of the reactor. Draw a horizontal line every 1M upward, and draw a vertical line every 1M from one side of the face to the other, so that the intersection of several horizontal lines and vertical lines will be formed on the whole face. Select sampling points from these intersections. The selection method is that the intersections of odd horizontal lines and odd vertical lines and even horizontal lines and even vertical lines are sampling points. The selected sub-samples are connected by points, as if multiple plum petals are nested together. Therefore, this sampling method is called plum blossom sampling method. (2) The excavation depth is 0.4M, and the coal on the surface of the coal pile is not suitable for sampling. Because the coal on the surface of the pile has been oxidized to varying degrees in the air, its properties have gradually changed. The mass of each sub-sample is not less than 2KG. The use angle of the sampling shovel is perpendicular to the surface of the coal pile. When you meet gangue, lump and pyrite, you should not abandon them at will.