Coal sample blending usually uses the heap cone method. The cracked and sieved coal is scooped up one by one and piled on the steel plate into a cone. Due to the segregation of particles of large and small particles in the coal sample, the coal with a larger particle size is always scattered around the bottom of the cone.

Fine-grained coal and coal powder are gathered at the middle and top of the cone. In order to evenly disperse the large and small particles along the circumference, the coal around the cone must be carefully scooped up around the cone when the cone is piled, and the coal around the cone bottom must be scooped down two or three times from the top of the cone to make It can slide down evenly along the top to the four sides, and the blending work is repeated three times, thinking that the particle size is evenly dispersed, can be reduced.