Definition
Grinding and dispersing mixer is a kind of laboratory pretreatment equipment that integrates grinding, dispersing and mixing functions. It refines and homogenizes the solid particles through mechanical force and makes them stably suspended in liquid medium. This equipment is commonly used to process slurries, suspensions, emulsions, and other systems, especially for samples with high viscosity or hard particles. Its core goal is to achieve microscopic homogenization of materials and provide a reference sample with good reproducibility for subsequent analysis or production.
How it works:
The core working principle of the equipment is based on the synergy of three physical effects: shear, impact and friction. When the stirring paddle or grinding disc rotates at high speed, it exerts tangential force on the material, allowing the agglomerated particles to depolymerize. At the same time, the internal grinding media (such as glass beads and zirconia beads) impact and squeeze the particles during movement to reduce the particle size. The material is repeatedly circulated in the rotor and stator gap, subjected to strong laminar shear and turbulence, so as to complete the dispersion and grinding. At a specific speed, the centrifugal force generated by the equipment promotes the material to flow outward, creating a continuous internal circulation path that ensures uniformity of processing.
Measurement methods and key indicators
The performance evaluation of grinding and dispersing mixers is often quantified by the following methods.
Particle size distribution: The particle size change of materials before and after treatment is measured by laser diffraction or dynamic light scattering method, and common indicators include D10, D50 and D90.
Dispersion uniformity: Determined by measuring the viscosity change of the system or observing the degree of particle agglomeration under a microscope.
Energy Consumption and Efficiency: Record the energy consumption required to process a specific volume or weight of material and calculate the specific energy input in combination with time.
Handling temperature: Use built-in or external temperature sensors to monitor the temperature rise of the material during grinding to avoid denaturation of heat-sensitive samples.
Influencing factors
The actual effect of the equipment is constrained by a variety of factors. The first is the rotation speed and linear speed, although high speed can improve the shear strength, but it may also cause the material temperature rise too quickly or excessive crushing. The second is the material, diameter and filling rate of the grinding medium: zirconia beads have high hardness and strong wear resistance, which is suitable for hard samples; Glass beads are less expensive but easy to break; The filling rate is usually recommended between sixty and eighty percent. In addition, the initial particle size, viscosity and solids content of the material itself also significantly affect efficiency: high viscosity materials require more torque drives, while high solids content can exacerbate media wear. Finally, the processing time should be optimized through pre-experiments to avoid particle size rebound or equipment idling and air consumption caused by excessive grinding.
Applications:
Under the framework of this laboratory testing instrument, grinding dispersion mixers are widely used in non-medical fields. In materials science, it is used to prepare battery electrode pastes, ceramic coatings, magnetic material pastes, and nanoscale powders. In the chemical industry, it is used for the refinement and homogenization of paints, inks, pigments and dyes; In the field of food testing, it is used for particle grinding and emulsification of complex fluids such as chocolate, jam, and seasonings. In environmental testing, it is used for the pretreatment of soil samples or solid waste to achieve particle homogenization and improve extraction efficiency. Additionally, in the electronics industry, it is used in precision mixing processes for conductive adhesives and thermal pastes.
Selection guide
When selecting, the characteristics of the material should be confirmed first: including hardness, viscosity, corrosiveness and sensitivity to temperature changes. For inorganic powders with higher hardness, it is recommended to choose models with carbide or ceramic rotor stator assemblies and equipped with high-power motors. For pastes with viscosity exceeding a certain range, it is necessary to choose a paste with a larger blade diameter or stronger torque drive capability. Throughput is also an important consideration: lab-grade equipment is typically suitable for milliliters to liter volumes, and container types should be selected for easy cleaning and changing. In addition, devices with adjustable speed, timing function, and temperature monitoring interface can improve the flexibility and reproducibility of experiments. Finally, noise and sealing performance should not be ignored, especially when dealing with samples with large volatile solvents or dust, a fully sealed design should be prioritized.
Operation and maintenance points
Before each use, check whether the parts of the equipment are tight and whether the rotor and container are evenly cleared. Before starting, it is necessary to confirm whether the initial state of the material is suitable for direct grinding, and if necessary, pre-stirring can be carried out first. During operation, the rotation speed should be gradually increased to avoid instantaneous impact causing splashing or overloading of equipment. After processing, the power should be turned off before reducing the speed to prevent material settling or forming hard lumps. When cleaning, use solvents that are compatible with the material and pay attention to the protection of rotor bearings and seals. Regularly check the wear degree of the abrasive media and replace it as needed; If you stop using it for a long time, it should be thoroughly washed and kept dry for storage.
Frequently Asked Questions and Countermeasures
Material temperature is too high: the intermittent operation mode can be changed, or a cooling jacket can be added around the periphery of the container, or the processing speed can be reduced.
Particle agglomeration fails to effectively depolymerize: it may be due to insufficient rotation speed or excessive diameter of the grinding medium, so you can try to increase the speed or replace it with a smaller medium.
Abnormal vibration or noise of equipment: Check whether the rotor is dynamically balanced, whether the media is unevenly distributed, or whether the container is installed stably.
Abnormal viscosity of the sample after treatment: The specific surface area of the particles may increase due to excessive grinding, which can adsorb more dispersed media, and the processing time needs to be optimized.