General process information
Detergents are manufactured using a synthetic surfactant in place of the metal fatty acid salts that are used in soaps. Most of the powder detergents have soap in their mixture of ingredients, however it generally functions more as a foam depressant than as a surfactant.
Powder detergents are manufactured using various processes, such as spray drying, agglomeration, dry mixing or a combination of these.
Spray Drying Process
The different stages / operations performed in a spray drying process, are:
Dry (Sodium sulphate, Sodium tripolyphsophate(STP), Zeolite and others) and liquid ingredients are first combined into a slurry, or thick suspension, in a tank known as crutcher.
The slurry is heated and then pumped to the top of a tower where it is sprayed through nozzles (under high pressure) to create small droplets. The droplets fall through a current of hot air, thereby forming hollow granules as they dry.
Collected from the bottom of the spray tower, the dried granules are screened to obtain a relatively standard size.
After the granules have been cooled, heat sensitive ingredients, which are not compatible with the spray drying temperatures (like bleach, enzymes and fragrance) are added.
Traditional spray drying process produces relatively low-density detergent powders. Advancements in technology have enabled the soap and detergent manufacturers to reduce the air inside the granules during spray drying to obtain higher densities. The high-density detergent powders can be packed in much smaller packages than those needed previously.
Made in powder detergents, these detergents are sold as laundry powders, hard surface cleansers, dishwashing detergents, fabric conditioners etc.
Additional techniques include:
Agglomeration is detergent powder manufacturing chemical technique that results in high-density powders. The process involves blending of dry raw materials with liquid ingredients. The technique involves machines, such as a liquid binder, rolling or shear mixing that causes the ingredients to collide and adhere to each other, producing larger particles.
Dry mixing is a detergent powder manufacturing technique, which is used to blend dry raw materials. The technique may also involve the addition of small quantities of a liquid.