An article detailing the results has been published in the journal "Southern Siberian Scientific Bulletin." The study was conducted as part of the strategic academic leadership program "Priority 2030."
In the production of chemical substances where potassium chloride is dissolved, a fine crystalline composition is utilized because it has a higher dissolution rate than coarse-crystalline forms. The use of "fine" potassium chloride is relevant for the manufacture of artificial leather, synthetic rubbers, complex mineral fertilizers, as well as feed and baking yeast.
The particle sizes of potassium chloride depend on the conditions of its crystallization – the stage during which the crystalline nuclei of the substance form and grow. The scientific community has already discovered that applying ultrasound during this process can yield smaller-sized particles. However, this factor has not yet been studied in detail.
Scientists from Perm Polytechnic University investigated how specific parameters of ultrasonic treatment affect the size of the resulting potassium chloride and established the possibility of regulating the particle size distribution of the product.
The polytechnic researchers conducted laboratory experiments using a special reactor. Distilled water and chemically pure potassium chloride were introduced into it. The suspension was heated to 90°C and then cooled to 30°C. Throughout the experiment, the mixture was stirred and treated with ultrasound at a frequency of 22 kHz of varying intensity during cooling. Subsequently, the mixture was filtered, dried, and the particle size distribution of the resulting precipitate was determined.
"During crystallization with continuous ultrasonic exposure at increased intensity, smaller particles are obtained, primarily ranging from 0.071 to 0.14 millimeters. However, a large portion of such powdery fractions in the product is undesirable, and to reduce their content, it is better to perform ultrasonic treatment in pulses. This way, potassium chloride particles with sizes from 0.14 to 0.35 millimeters prevail," explains Konstantin Kuzminkh, a senior lecturer at the Department of Chemical Technologies at PNIPU.
The polytechnic researchers note that already formed large crystals of potassium chloride can also be ground. For this purpose, it is more effective to lower the frequency of ultrasound waves from 44 to 22 kHz, while increasing the duration and intensity of the treatment. In a denser liquid medium (in a saturated aqueous solution of potassium chloride), this process occurs at lower power values and with a higher grinding coefficient.
Scientists from Perm Polytechnic University have demonstrated that it is possible to regulate the particle size distribution of industrial potassium chloride using ultrasonic treatment. Its effectiveness during the crystal growth stage is significantly higher than when grinding already formed particles. The practical application of the results obtained will expand the range of applications for the product in domestic industry.