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Business and Services

Product development by powder mixing: A process with different mixing mechanisms

Developing products through powder mixing is a challenging process. Powders behave differently from liquids and can vary in properties such as flow, cohesion, particle size, density and shape. This makes powder mixing complex and requires a deep understanding of the materials and operation of mixing equipment. There are three mechanisms used in mixing of solids: convection, diffusion and shear. Convection mixing occurs when masses or groups of particles move from one location to another. In diffusion mixing, individual particles are evenly distributed throughout the mixture, while in shear mixing, groups of particles are mixed by forming sliding surfaces within the mixture.

Mixing powders is usually done by shaking, twisting, vibrating or other mechanical methods. However, the mixing process can also lead to segregation of powder mixtures, where particles with different densities separate from each other. It is therefore important to carefully control and evaluate the mixing process to prevent unwanted segregation. At Delft Solids Solutions, we have different types of mixing equipment available, such as diffusion mixers, convection mixers and high-speed mixers, which are suitable for mixing different types of powders. We also offer product characterisation, such as particle size analysis and segregation analysis, to assess the quality of the mixing process. Contact us for more information on our powder mixing product development capabilities.

What are the two main categories of size enhancement in powder processing? 

The two main categories of size augmentation in powder processing are processes aimed at controlling functional properties, such as powder granulation, and processes aimed at producing specific shapes, such as tablets and pellets. Powder granulation is also referred to as tumbling agglomeration. Powder granulation is a size enhancement process in which a powder material is converted into larger entities, resulting in a significantly larger aggregate with a porous structure. Powder granulation can be carried out by various methods, such as tumble/growth size enlargement, in which agglomerates of approximately spherical shape are produced by accumulation of fine particles during tumbling. These resulting granules are often weak and require binder to facilitate their formation and achieve good final strength. Powder granulation allows the granules to flow better and produce less dust compared to the original powder material. Powder granulation also prevents segregation of powder mixtures, as the individual particles of different composition can no longer move freely. In powder granulation/agglomeration, the amount of binding liquid and the rotation speed of the granulation unit are important factors.