Application of laser particle size analyzer

In the propagation of light, the wavefront is limited by apertures or particles that are equivalent to the wavelength scale, and diffraction and scattering of the energy of diffraction and scattering occurs in the space by interference of the emission of the source wave at the confined wavefront as the source. The distribution is related to the wavelength of the light wave and the size of the pore or particle. With a laser as the light source, after the light has a monochromatic light with a certain wavelength, the spatial distribution of the diffracted and scattered light energy is only related to the particle diameter.

First, the principle of laser particle size analyzer The classic theory of diffraction and scattering [2][3] pointed out that in the propagation of light, the wavefront is limited by apertures or particles that are equivalent to the wavelength scale, and each wavelet at the confined wavefront is The emission of the source produces diffraction and scattering in spatial interference, and the spatial (angle) distribution of the diffracted and scattered light energy is related to the wavelength of the light wave and the size of the pore or particle. With a laser as the light source, the spatial (angle) distribution of the diffracted and scattered light energy is related only to the particle size after the light has a monochromatic light with a certain wavelength. The diffraction of the particle group determines how much each particle level corresponds to the light energy obtained at each particular angle. The proportion of each specific light energy in the total light energy should reflect the abundance of each particle level. According to this idea, a mathematics and physical model that characterizes the abundance of the particle size class and the light energy obtained at each specific angle can be established, and then the instrument can be developed to measure the light energy. The comparison of the light energy measured at a specific angle with the total light energy can be used to derive the particle group. The abundance ratio of the corresponding particle size class.

Second, characteristics The characteristics of this technology are:

Using the wet dispersion technology, the mechanical stirring makes the sample evenly dispersed, the ultrasonic high-frequency oscillation makes the agglomerated particles fully dispersed, and the electromagnetic circulating pump makes the size particles uniformly distributed in the entire circulation system, thereby fundamentally ensuring the wide distribution of the sample tested. Accurately repeat.

The test operation is simple and quick: put the dispersion medium and the sample to be tested, start the ultrasonic generator to fully disperse the sample, and then start the circulation pump. The actual test process is only a few seconds. The test results are displayed, printed and recorded in the form of particle size distribution data table, distribution curve, specific surface area, D10, D50, D90, etc.

The output data is rich and intuitive: The software of this instrument can run on various computer windows platforms and has the characteristics of simple and intuitive operation. It not only dynamically detects the samples, but also has powerful data processing and output functions. Users can choose and design the ideal The table and graphic output. III. Application of laser particle size analyzer in cement grouting engineering In the cement grouting project, due to the size of cement particles, it directly affects the grouting effect. Therefore, it is very important to test the particle size and distribution of cement particles. Necessary, we used laser particle size analyzer to carry out cement particle sizing for "Furongshan" ordinary portland cement and "Three Gorges" brand ultrafine cement in the consolidation grouting test for Class III2 rock mass of the dam foundation of Xiangjiaba Hydropower Station. Tests and tests have proved that the laser particle size analyzer has the characteristics of high detection speed, good data repeatability, data processing and output practicality, simplicity, and intuitiveness, and has achieved good results.

Wet-grinding cement particle size analysis and test test study: The use of "Three Gorges" brand ultrafine cement, preparation of cement slurry, particle size analysis of the cement slurry test, 20 minutes test once, before the test using a colloid mill for high-speed stirring, the test proved that After 4 hours, the D50 of cement particle size does not change much. That is, under high-speed stirring or wet grinding conditions, the effect of cement hydration reaction on the change of cement particle size is not significant, and the laser particle size analyzer has a small volume, high test speed, and results. Intuitive features, suitable for on-site wet grinding cement particle size testing.

Fourth, the laser particle size analyzer and centrifugal sedimentation particle distribution analyzer comparison Centrifugal sedimentation particle distribution analyzer is a non-contact particle size distribution measurement device using liquid phase sedimentation method. It is based on Stokes' law and Chamber-Beel's law. It uses gravitational settlement and centrifugal sedimentation as a means to control the entire test process with a computer. It has characteristics such as fast wide area, good repeatability, and easy operation. Compared with the laser particle size analyzer, the result is the weight percentage distribution, and the result measured by the laser particle size analyzer is the volume percentage distribution, but the biggest drawback of the settled particle distribution analyzer is that the measurement time is long and the measurement time is: 5-30 minutes, while the laser particle size analyzer measurement time is about 2-3 minutes, more rapid, and the error caused by the personnel operation is smaller, more suitable for cement particle size analysis and testing.