Introduction to Mercury Cells

Mercury Cells are one of the oldest and most reliable technologies in chlor-alkali plants, designed for the simultaneous production of high-purity chlorine gas and caustic soda (NaOH). These cells have been used for decades in the chemical and petrochemical industries, and, due to their ability to consistently produce high-quality products, long service life, and precise process control, they still find applications in certain industries.

In mercury cells, mercury acts as a liquid cathode, guiding sodium ions to the mercury surface where they combine with hydroxide ions to produce caustic soda. This technology allows for the production of NaOH with high purity and precise concentration control, enhancing product value and improving plant efficiency.

Operation of Mercury Cells

The operation of a mercury cell is based on the electrolysis of a concentrated brine solution. The pretreated brine is fed into the cell, and a DC passes from the anode to the liquid mercury cathode. Chloride ions migrate toward the anode to produce chlorine gas, while sodium ions react with mercury to form a sodium-mercury amalgam. The amalgam is then transferred to the hydrolysis unit, where it reacts with water to produce NaOH and hydrogen. This process enables precise control over NaOH concentration and purity, while delivering high-quality chlorine output.

Design and Implementation of Mercury Cells

The design of mercury cells is based on production capacity, brine quality, safety standards, and environmental regulations. Selection of corrosion-resistant materials, the design of the anode and mercury cathode, and the hydrolysis unit ensure stable operation and optimized energy efficiency. These cells are modular and scalable, allowing capacity expansion or partial cell maintenance without shutting down the entire unit. Instrumentation and monitoring systems guarantee uniform performance and product quality, ensuring that chlor-alkali units operate under optimal conditions.

Conclusion

Mercury Cells are a traditional, reliable, and high-quality solution for chlorine and caustic soda production. Despite the emergence of modern technologies, they remain applicable in specific industries. With engineered design, precise process control, and proper maintenance services, mercury cells provide stable, safe, and economical production of basic chemical products. Their use enhances production efficiency, ensures product quality, and reduces operational risks, making them a suitable choice for industrial units requiring consistent output and high-purity NaOH.