For the separation of KCl from NaCl, the following three methods can be used:
- 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 with increasing temperature. Through the LiquiSonic® Measurement technology the hot dissolution process can be monitored inline at various points and the KCl concentration can be precisely determined.
Measurement of sound velocity in a KCl suspension
Application
Due to the different solubility properties, a mother liquor is first produced in the hot dissolution process, which is saturated with NaCl and KCl. This is heated (solvent liquor) and mixed with additional raw salt. Most of the KCl dissolves, while the NaCl is removed as an undissolved residue in the clarifier. The dissolved KCl is separated in multi-stage cooling crystallizations. Purities of up to 99% can be achieved through subsequent thickening. The remaining mother liquor is fed as new solvent liquor intothe process.
Objective of Measurement technology LiquiSonic®is to ensure process stability during the hot dissolution process, for example when dissolving raw salt in the mother liquor or in crystallization. This enables optimal process yield with minimized energy use and quality improvement through continuous data recording.
Installation
The LiquiSonic® Measurement technology is installed directly in the crystallizer or at the lower outlet to determine the suspension density [g/l] and to determine 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
- it is advisable to install from below 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 multiple measurement points:
- Dissolution of raw salt (sylvinite)
- Clarification
- Crystallization
- KCl thickener
Typical measuring range:
Concentration range: 1100 - 1600 g/l
Temperature range: 70 - 110°C
Customer benefits
The inline measurement system LiquiSonic®enables precise analysis of process concentrations using sound velocity. An automatic, concentration-controlled process management prevents blockage of the system (too slow process management) and increases yield (too fast process management). Without moving parts and using special material (titanium), it guarantees long-term reliable process analysis and monitoring.
Further advantages for the user are:
- Optimal plant control through real-time information about the process state
- Increase in the efficiency of clarifiers and thickeners
- Reduction of salt losses through wastewater
- Detection of process disturbances in seconds
- Cost savings, particularly in energy and material
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 high-purity salts for the chemical and pharmaceutical industries.
