The role of binder in the process of ball pressing

The binder is generally a liquid substance such as pulp waste liquid, syrup waste liquid, and water glass. There are two aspects to the ball:

1. The binder is adsorbed on the surface of the material in a highly dispersed manner, and penetrates into the crack of the particles under the action of pressure, thereby increasing the contact area inside and outside the particle and improving the deformation ability of the material;

2. Reduce the friction between the material particles and between the particles and the forming mold. Evenly wrapping a layer of binder on the surface of the material particles greatly reduces the roughness of the surface of the particles, which is beneficial to the sliding between the materials; when the particles of the material move relative to the mold, the adhesive lubricates the mold to make the material and the mold Reduced friction is beneficial for ball formation and increased mold life.

The molding pressure and the amount of the binder are two closely related factors, which are mutually influential factors, and a certain amount of binder is required under a certain pressure. During the ball pressing process, the material particles are closely arranged. At this time, a capillary is formed between the particles. Under the action of pressure, the internal binder is pressed against the surface of the pellet along the capillary tube, so that the particles are more tight under a certain pressure. If the amount of binder is small or the molding pressure is insufficient, the friction between the particles cannot be effectively reduced or the force required for the tight alignment of the particles cannot be obtained, and the strength of the pellets is affected; if the amount of the binder is excessive or the molding pressure is too large, the viscosity is too high. The film on the surface of the material particles is too thick and cannot be discharged in time under a certain pressure, which hinders the bonding between the particles of the material or the excessive discharge of the binder to the surface of the sphere under excessive pressure, which will affect the strength of the pellet.