Improving the Performance of a Salt Production Plant by Using Nanofiltration as a Pretreatment

Area of Science:

• Industrial Chemistry
• Water Treatment Technologies
• Materials Science

Background:

• The Dębieńsko evaporated salt plant faces high operating costs due to energy-intensive processes.
• Saline mine water treatment for sodium chloride production presents challenges in efficiency and waste management.

Purpose of the Study:

• To enhance the performance and reduce the operating costs of an evaporated salt plant.
• To investigate the efficacy of a two-pass nanofiltration pretreatment with intermediate gypsum crystallization.

Main Methods:

• Pilot-scale research was conducted on a two-pass nanofiltration system.
• Gypsum crystallization was implemented as an intermediate step in the pretreatment process.
• Analysis of brine composition and salt yield before and after the proposed treatment.

Main Results:

• The pretreatment effectively removed calcium, magnesium, and sulfate ions from saline mine water.
• Sodium chloride yield increased from 58.8% to 76.1%.
• Energy consumption decreased from 1350 kWh/t to 1068 kWh/t, and post-crystallization lye volume reduced by 66%.

Conclusions:

• The proposed two-pass nanofiltration with intermediate gypsum crystallization is a viable method for improving salt production efficiency.
• The process offers significant reductions in energy consumption and waste volume.
• A valuable magnesium-rich stream is generated, opening possibilities for magnesium hydroxide recovery.