The following three processes can be used to separate KCl from NaCl:
- Hot dissolution process
- Electrostatic separation
- Flotation
In the hot dissolution process, the separation principle is based on the different solubility of KCl and NaCl. While NaCl dissolves well regardless of temperature, the solubility of KCl increases as temperature rises. Through the LiquiSonic® Measurement technology the hot dissolution process can be monitored inline at various points and the KCl concentration can be determined precisely.
Measurement of the sound velocity in a KCl suspension
Application
Due to the different dissolution properties, in the hot dissolution process a mother liquor saturated with NaCl and KCl is first produced. This is heated (dissolving liquor) and mixed with additional crude salt. In the process, most of the KCl dissolves, while the NaCl is removed in the clarifier as an undissolved residue. The dissolved KCl is separated in multi-stage cooling crystallizations. The subsequent thickening can achieve purities of up to 99%. The remaining mother liquor is fed back into the process as new dissolving liquor.
The goal of the LiquiSonic® measurement technologyis to ensure process stability in the hot dissolution process, for example when dissolving crude salt in the mother liquor or during crystallization. This enables optimum process yield with minimized energy consumption as well as improved quality through permanent data recording.
Installation
The LiquiSonic® Measurement technology is installed directly in the crystallizer or at the lower outlet in order to determine the suspension density [g/l] and the density of the mother liquor in the overflow.
Installation notes:
- in the crystallizer: sensor length 300 - 500 mm
- in pipelines (usually DN300 to DN800): sensor length 250 mm
- installation from below is advisable for measurement in partially filled pipelines
The LiquiSonic® Controller 30 can be connected to up to 4 sensors. This allows the hot dissolution process to be monitored at several measuring points:
- Dissolution of the crude salt (sylvinite)
- Clarification
- Crystallization
- KCl thickener
Typical measuring range:
Concentration range: 1100 - 1600 g/l
Temperature range: 70 - 110°C
Customer benefits
The inline measuring system LiquiSonic®enables precise analysis of process concentrations by means of sound velocity. Automatic, concentration-controlled process management prevents blockage of the plant (process running too slowly) and increases yield (process running too quickly). Without moving parts and through the use of special material (titanium), it guarantees reliable long-term process analysis and monitoring.
Additional benefits for the user are:
- Optimal plant control through real-time information about the process status
- Increase in the efficiency of clarifier and thickener
- Reduction of salt losses through wastewater
- Detection of process disturbances within seconds
- Cost savings, especially in energy and materials
The extraction of sylvinite (a mixture of potassium chloride KCl and sodium chloride NaCl) plays a crucial role in the production of mineral fertilizers as well as highly pure salts for the chemical and pharmaceutical industries.
