1, the moisture content of particles is too low. When the particles are dried, if the moisture content is too low, the surface of the particles will become hard, and there will still be some moisture inside, which will lead to drying shrinkage, shrinkage and even cracking and crushing of the particle surface.
2. The drying temperature is too high. Too high drying temperature will make the particle surface dry quickly, and the internal moisture can not escape from the particle surface in time, forming particle surface hardening, generating internal stress and leading to particle breakage.