Particle Technologies

Soldification
We can define solidification as a widely applied process that shapes a melt into a specific form. For instance, a fertilizer melt is prilled into spherical fertilizer particles to conveniently distribute over the land to grow crops. Another example is the casting of iron into plates or sheets, which are used in construction, automotive body panels, and industrial process equipment. Solidification also includes processes that lead to the formation of amorphous or highly viscous particles which have a non-crystalline structure. Polymer solidification, for instance, involves the cooling or curing of a polymer melt to decrease the viscosity and convert it into a particulate product or a specific shape that is (for a large part) non-crystalline. For solidification processes the emphasis is on the physical characteristics of the shaped product and less on the specific arrangement of atoms or molecules within the solid.

Crystallization
Crystallization is a particle technology that involves the formation of solid particles with a well-defined crystal structure from a solution or melt. It is a widely used technique in various industries, including pharmaceuticals, chemicals, and materials science for purification and separation. 

Crystallization selectively forms and grows crystalline particles. By carefully controlling the crystallization conditions, highly pure crystals with specific properties can be obtained from a single crystallization process step. Crystallization is specifically employed to separate or purify substances into a particulate product. The product from a chemical synthesis can for instance be purified by crystallization.

Particle Modification
Particle technologies can further be used to intentionally modify particles and their properties. During such a process, particles in the feed are transformed to particles with the desired particle properties or functionalities. For instance, milling and grinding processes are employed to reduce the particle size of particulate materials. These techniques involve mechanical forces that break down larger particles into smaller ones. Granulation refers to the process of agglomerating fine particles into larger granules. It is commonly used in chemical industry, where small particles are combined and bound together using binders or additives into larger particles to improve flowability or compressibility.

Another example of particle modification is encapsulation or coating. During the process a thin layer of material is applied onto the surface of particles. This can be done through methods like spray drying, fluidized bed coating, or chemical vapor deposition. Coatings can provide functionalities such as controlled release, improved stability, enhanced compatibility, or modified surface properties of the particles.

Particle Use
Particles can be used in processes to efficiently achieve purified and reaction products. For instance, adsorbent particles such as activated carbon, zeolites, and silica gel remove or recover specific substances from gases or liquids. The adsorbent particles possess a high surface area, allowing for increased adsorption capacity. Adsorbent particles can be used in a wide range of processes such as gas purification, water treatment, air pollution control, and adsorption chromatography.

Particles serve as catalysts to accelerate chemical reactions by providing an active surface which reagents quickly react to the preferred reaction product. Catalyst particles play a crucial role in numerous industrial processes, including petroleum refining, chemical synthesis, environmental remediation, and emission control. 

Particle Separation
Mechanical separations involve the use of physical mechanisms to separate particles based on their size, density, or other physical properties. 
For instance filtration is a process that separates solid particles from a fluid (liquid or gas) by passing the mixture through a porous medium, called a filter. The filter retains the solid particles while allowing the fluid to pass through. The choice of filter medium depends on the particle size, desired filtration efficiency, and compatibility with the fluid and particles involved.
Sieving involves the passing of a mixture of particles through a sieve or screen with specific openings or mesh sizes. The smaller particles pass through the sieve, while the larger particles are retained.
Centrifugal forces are used in cyclone separators to separate particles from a gas or liquid stream based on particle size and density. The mixture enters a cylindrical chamber tangentially, creating a swirling motion. Due to the centrifugal force, the heavier particles move toward the outer wall and are collected, while the lighter particles and the gas or liquid continue to the outlet.