Convention teaches that ZLD requires energy-intensive boiling to produce solids. Our engineers recently broke that convention and helped a mining client achieve solid salt production in a novel membrane-chiller hybrid plant using UHP-RO.
Eutectic chilled crystallization
To produce solids, chilled crystallizers need to overcome a much lower thermodynamic barrier than evaporators. For very specific solution chemistries, chilled crystallization is a highly competitive option for zero liquid discharge.
ZERO OR MINIMAL
EVAPORATORS & CRYSTALLIZERS
Eutectic Chilled Crystallization
Eutectic Chilled Crystallization (ECC) cools a fluid, forcing salts to precipitate. Although it works only for specific salt-ion pairs (e.g. Na2SO4), it leverages the efficiency of Carnot cycles (1 unit of power equates to 3 units of heat), making it a great fit for some projects.
If a salt-ion pair in a concentrated brine has a steep temperature-solubility relationship (e.g. Na2SO4), then cooling will form salt precipitants. The salt can be separated out while the brine is recycled for further processing. Some salts produce hydrated crystals (e.g. Na2SO4⋅10H2O) which remove water during the crystallization process.
Saltworks holds proprietary technology to complete the chilled crystallization process in a closed loop. We package this with intelligent controls in our SaltMaker ChilledCrys system, which continually removes water and salt, enabling cost and energy efficient ZLD.
When to Use SaltMaker ChilledCrys?
Chilled crystallization may be a viable option for zero liquid discharge (ZLD) or minimal liquid discharge (MLD)—if your solution consists predominantly (>90%) of the following ion pairs:
- Sodium or potassium sulfate
- Sodium or ammonium carbonate/bicarbonate
For example, cooling a solution of 200,000 mg/L sodium sulfate from 20°C to 10°C will precipitate over half of the sodium sulfate as a solid, which is then easy to separate. The result is a solution with a final concentration of 100,000 mg/L sodium sulfate and the emergence of ~50% of the salt as a solid. Every solution is different, our engineers can complete an assessment for yours.
ECC ≠ Freeze Crystallization
SaltMaker ChilledCrys uses chilled crystallization, which should not be confused with its cousin: freeze crystallization (FC). FC was worked on extensively in the 1950s and 60s.
- In FC, small ice particles (known as frazil) are formed. Salt is rejected from the ice during freezing. The ice is then separated, washed, and thawed leaving pure water behind.
- In ECC, rather than forming ice to remove water from the system, we use industrialized desalination technology, and then form specific salt-ion pairs when chilling, which are separated from the solution.
Contact us today with your water chemistry and treatment goals. Our experts can help you determine if SaltMaker ChilledCrys is the right fit for your MLD or ZLD project.
SaltMaker ChilledCrys Applications
SaltMaker ChilledCrys Related Resources
Today, Saltworks officially launched a new product for shale operators: the SaltMaker AirBreather. Building on the success of the SaltMaker MultiEffect – Saltworks’ hallmark evaporator crystallizer – the SaltMaker AirBreather was designed with the shale end use in mind: high capacity, low cost, employ low grade heat, and robust modular operations.
The SaltMaker MultiEffect evaporator crystallizer is a one-step brine treatment plant for volume minimization and zero liquid discharge (ZLD) applications. Its unique evaporative crystallizer design is built to treat the toughest waters and to simplify your brine treatment project.