The SPECTester has been developed to enable the easy and rapid assessment and the quantification of the segregation taking place in a product mixture containing around six distinctive components.
However, by employing some simple extra steps, the tester can analyze a product composed of differently-sized particles of the same material. Simply put, they can observe segregation due to particle size. The extra steps are as follows:
- Firstly, the material is riffled to acquire a representative sample. About 2.5 liters of material is required to make sure that an adequate amount of sample is left for the SPECTester analysis.
- A portion of this sample is then taken and sieved to produce two components (both fine and coarse).
- The PSD of the fine and coarse particles is quantified and the minimum particle size (D10, D50, and D90) and the maximum particle size are determined.
- The percentage concentration by mass of the fine and coarse particles is determined using the final sieved sample.
The fine and coarse particles acquired during this sieving process will be the pure components used in the component trays at the time of the SPECTester’s analysis. The material obtained from the riffling step is re-combined and mixed well to fill the feeder hopper.
Some additional information on the industry-standard will be required, such as:
- The cumulative PSD values (minimum: D10, D50, and D90, and maximum values)
- The profile bin values
The bottom part of the SetUp2 screen is inactive in the ‘Component Mode’ operation. The ‘Particle Size Mode’ requires the inclusion of the profile bin values, and also the cumulative PSD values (minimum: D10, D50, and D90, and the maximum values).
Either differential view spectra or component spectra are used to measure the concentration of fine and coarse particles just like any other pure components in a mixture. The SPECTester uses the concentrations of these fine and coarse particles together with the particle size data to calculate the particle size of any particle size bin specified in the profile bin values entered in SetUp2 screen.
As an example, let us say that four particle size bins are being used. These are the PS Bin One (1-650), PS Bin Two (651-1000), PS Bin Three (1001-1500), and the PS Bin Four (1501-2700). The concentration of each of these sized bins can be mapped as a function of the dimensionless radius. It is not necessary to cover the whole PS range with the bin sizes entered in the SetUp2 screen.
Component Spectra Preview
In the ‘Component Spectra’ mode, the spectral signatures of the fine and coarse particles are comparable. The variation in the spectral signature (as observed by the SPECTester) is because of the difference in intensity of hue produced as a result of the difference in particle size. The finer material disperses more light, and will therefore have the more intense spectral signature. It is to be noted that the peaks and valleys of the two spectral signatures remain the same.
Differential View Preview
In ‘Differential View’ mode, the spectral signatures of fine and coarse particles are different since the spectral intensity curves are subtracted from one another. The main component spectral intensity curve will be configured to zero and the other component will be deducted from that value to provide the differential view spectra.
In this instance, the coarse particles (major component shown as a white line) demonstrate zero intensity and the fine particles (the blue line) are deducted to provide the differential spectra as shown below.
The preview mode is chosen for the convenience of the user. The resulting segregation profile is basically the same for both preview modes.
This information has been sourced, reviewed and adapted from materials provided by Particulate Systems.
For more information on this source, please visit Particulate Systems.