Definition
Powder liquid solid disperser is a laboratory or industrial equipment used to evenly disperse powder or solid particles in a liquid medium to form a stable suspension system. This equipment realizes the deagglomeration and uniform distribution of solid phases in the liquid phase through mechanical action, and is a key instrument for sample preparation in many fields such as materials science, chemical industry, food, and coatings.
Principle
The working principle of powder liquid solid disperser is based on the theory of fluid mechanics and mechanical shear. The equipment typically generates strong mechanical shear, impact, and turbulence within the stator or vessel through a rotor or dispersion disc that rotates at high speeds. The solid particles are broken and dispersed under the action of shear, and the liquid medium forms a circular flow, which promotes the full contact and wetting of the particles with the liquid. The dispersion process can be described as the aggregate overcoming cohesion under shear stress and breaking up, and then being encased by a liquid medium and stably dispersed. The dispersion effect is closely related to the energy density of the input, and the energy input E can be expressed as the function relationship between the power P of the device and the effective action time t: E ∝ P·t.
Measurement and evaluation methods
The evaluation of dispersion effect is usually judged by a multi-index synthesis. Particle size distribution is the core parameter, which can be measured by laser particle size analyzer to characterize the degree of dispersion with characteristic particle sizes such as D50 and D90. The stability of the suspension system can be analyzed by standing and observing the stratification time, or by using centrifugal sedimentation method and zeta potentiometer. Visual observation and microscopy can visually judge the aggregation. In addition, viscometers can be used to measure changes in the rheological properties of dispersed systems, indirectly reflecting the uniformity of dispersion.
Influencing factors
The dispersion effect is affected by multiple factors. Equipment parameters include rotor line speed, dispersion disc shape and diameter, power input and action time. The process conditions involve dispersion temperature, feeding sequence and speed. In terms of material characteristics, the particle size, density, surface energy, and wettability of the powder itself, as well as the viscosity, polarity and surface tension of the liquid medium all have significant effects on the dispersion process. Environmental conditions such as ambient humidity can also affect powder flowability. Optimizing the dispersion process requires systematic adjustment of these parameters.
Applications
Powder liquid solid dispersing machines have a wide range of uses in several industries. In the coatings and inks industry, it is used for the dispersion of pigments in substrates. The field of nanomaterials is used for the deagglomeration of nanomaterials such as carbon nanotubes and graphene in solvents. The battery industry is used in the preparation of electrode slurries. The food industry is used for the uniform mixing of powder ingredients in liquids. The cosmetics industry is used for the emulsification and dispersion of powder texture components. In addition, it also plays an important role in the research and development and quality inspection of ceramic pastes, dyes, adhesives and other products.
Selection considerations
Choosing a suitable powder liquid solid disperser requires comprehensive consideration of application needs. First, it is necessary to clarify the properties of the material being treated, such as solid hardness, expected final particle size, processing volume, and liquid viscosity. Choose the type of equipment based on the sample characteristics, such as a high-shear disperser, stir disperser, or grinding disperser. Pay attention to the technical parameters of the equipment, including power range, speed control accuracy, corrosion resistance and wear resistance of the material. In terms of safety, the design of equipment protection needs to be considered. In addition, the cleanability, noise level and compatibility of the equipment with existing processes should also be included in the assessment. It is recommended to verify the suitability of the equipment for a specific material through sample testing.