Industrial manufacture of asphalt emulsion uses custom made equipment to provide thorough mixing capability to provide the fineness and stability of dispersion required to meet the desired asphalt emulsion properties. While high-pressure static mixers and high shear mechanical mixer may be used, colloid mills are more common in the manufacture of asphalt emulsion.
While there are various types of colloid mills, the most common characteristics are an adjustable or fixed air gap between the rotor and stator and fixed or variable rotor rotation speed. The air gap spacing has a direct effect on emulsion fineness, while rotor speed affects the size and distribution of the asphalt particles. At certain critical speeds, a decantation phenomena may occur causing a reduction in emulsion quality.
The emulsion manufacturing process is a continuous process whereby the dispersing medium is continuously fed with the dispersing and dispersed phases by adjustable flow rate pumps. Mass flow meters may be incorporated to regulate material feed. As stated previously, certain emulsions have special characteristics and must be manufactured under pressure in specially designed colloid mills with necessary cooling provide to prevent boiling of the finished emulsion.