The characteristics of dry roller press granulation
Powder granulation technology as powder body the one of the most important branches of the process, with the improvement of environmental protection demand and production process automation degree, its importance is increasingly obvious."A granular powder products" has become the inevitable trend of world powder processing technology.Dry roller press granulation with low energy consumption, without adding other adhesives, low investment, technology features such as wide range of ability.
The strength of the particles of powder product processing, its significance is mainly reflected in three aspects:
Reduce dust pollution, improve labor operation conditions.
Meet the requirements of production process, such as increasing porosity and specific surface area, improving the heat transfer, etc.
Pieces to improve product physical properties (such as liquidity, air permeability, bulk density) avoid subsequent operation process, drying, screening, measuring) (measuring, ingredients, etc.) and use process segregation, pulsating, agglomerate, Bridges and other adverse effects.In order to improve the production and use of process automation, closed operation.
Powder granulation technology generally has two kinds: wet and dry granulation.Dry process is under the condition of not adding binder, by squeezing clumps or slices, and then the crushing, screening granular products.Wet method is mainly roller, disc, melting, spray and spray granulation.In agricultural production, for example: until the 1920 s, are powder applied fertilizers.Although convenient powder mixed fertilizer, but there are many drawbacks: such as segregation, agglomerate, liquidity is poor, dust formed in the process of application of vulnerability and erosion.But with the continuous development of granulation technology, these unfavorable factors are gradually resolved.
In wet granulation, the liquid binder capillary effect produced by the wet strength plays a vital role, in the subsequent stage of drying, the chemical reaction between components and solute the crystallization of the solid, crystal bridge made by particle shape.The technical representative with circular grinding equipment, roller, fluidization device, etc.No binder extrusion granulation technology is a very competitive.Under normal circumstances, the particles are not formed by a solid bridge between particles, but by molecular force between the formation of granular strength.Due to the force, shorter distance, requirements of particle size close to the external pressure, pressurized way can be a way out (with a diameter of the pore pressure of the material) or squeeze the way (in both sides of the material pressure), if the squeeze in between the two rollers rotating in the opposite direction of roll gap, the granulation process is dry roller pressure.