If the cohesive forces (particulate cohesion, valence forces, recrystallization, van Der Waals forces…) between the particles are low, a binder has to be used before agglomeration. The physical properties of the feed material, the end use of the briquettes and the cost of binder addition have to be taken into account before a selection is made. A large variety of (liquid or solid) binders is offered: starch, bentonite, bitumen, lime, cement, water, flour, lignosulphonates, molasses, polymer, resin, sodium silicate, etc…
The briquettes are obtained at a low or high pressure and can undergo mechanical or thermal treatment according to the characteristics of the processed material, the binder used and the desired end product. Considering the large variety of products to be processed and the binders used, the range of mixers designed and proposed by SAHUT-CONREUR is specifically adapted to each type of briquetting:
- Vertical mixers or pug mills, for instance for briquetting of coal with bitumen.
- Twin screw mixers, for instance for briquetting of some chemicals with water ; these mixers can be equipped with heating or cooling jacket, as the case may be.
- Horizontal or ploughshare mixers, for instance for briquetting of some minerals with molasses ; these mixers can also be equipped with heating or cooling jacket, as the case may be.
According to the material, the main stages of the process can be as follows:
- Product preparation unit (screening-crushing, drying, sieving)
- Dosing and mixing of product with binder
- Briquetting unit
- Post treatment of the briquettes (air or oven drying, curing, polymerization, aging)