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Particle size characterization of suspensions using ultrasonic method

Özçelik , Esma
Particle size is very important in many areas of industry and production processes in industries. For example, medicine, paint, etc. Therefore, it is important to obtain the particle size in a suspension. Particle size analysis can be performed by different methods. The aim of this study is to determine particle size by combining data from ultrasonic method and settling information. The fact that the ultrasonic method is cheap, non-destructive and non-invasive makes ultrasonic method very advantageous. In this study, sand was chosen for particle size analysis. Firstly, density was calculated from the void ratio of sand. Sieve analysis was performed for sand particles and a mixture of sand with different particle size range of 38 μm to 150 μm and 38 μm to 90 μm were prepared. The attenuation of the sound waves when the ultrasonic method enters an environment is based on the loss of energy. This method is used by taking measurements using Ultrasonic Instrument (UDV), DOP 2000 device. These measurements were performed by recording the intensity of ultrasound waves at 1 MHz at constant frequency. As the concentration increases, the attenuation rate of the sound wave increases. In order to use these measurements in sand suspension, 1%, 0.75%, 0.5% 0.25% 0.125% and 0.0625% weight percent suspensions were prepared and calibrated. After the calibration was completed, %1 weight percent sand suspension was prepared. This suspension was placed in the test apparatus and fixed to this apparatus in the ultrasonic probe and measurements were taken from the first to the thirtieth minute. Inspired by the Andreasen pipette method, continuous ultrasonic measurements were carried out instead of taking samples continuously from the suspension. Particle size analysis was performed by combining Andreasen pipette method, settling data and ultrasonic method. The experiment was performed three times for repeatability. According to sieve analysis, particle mixture contains 4.61% particle size between 38 μm to 63 μm, 27.56% particle size between 63 μm to 90 μm and 67.83% particle size between 90 μm to 150 μm The first settling experiment with 1% sand suspension, results reveal that, the 66% of the suspension contains particle sizes between 24.3 μm to 42 μm, 16.6% of the suspension contains the particles in the size of 42 μm to 59.5 μm and 8.8% of particles in the range of 59.5 μm to 150 μm. For the second sieve analysis, that is in the range of 38 μm to 90 μm, mixture of sand particles was prepared. Majority of the mixture contains particle size between 90 μm and 75 μm. Another set of experiments with 2% sand suspension of the particle mixture in the range of 38 μm to 90 μm are performed and the results indicate that, the suspension contains 46.2% of particles in the range of 90 μm to 59.5 μm. 24.2% of the suspension contains the particles in the size of 59.5 μm to 42 μm. 16.6% of the suspension contains particle sizes between 42 μm to 37.6 μm. 12.9% of the suspension represents the particles smaller than the 37.6 μm. Settling experiments shows that generality of the suspension contains particle size between 90 μm to 59.5 μm that is 46.2% percent. On the other hand, according to sieve analysis there should be no particles smaller than the 38 μm however, from settling experiments 12.9% of particle mixture has a particle size smaller than 37.6 μm.