Ceramic Valve Solutions for Sodium Bicarbonate Slurry

Alkaline Corrosion

Chemical corrosion: The heavy soda ash suspension contains not only NaHCO₃, but also unreacted NaCl, NH₄Cl, (NH₄)₂CO₃, NH₄HCO₃, and other salts. This complex salt solution creates a continuously corrosive chemical environment for metallic equipment

Mechanical Abrasion

Heavy soda ash suspension is a liquid-solid two-phase flow. As it passes through pipes and valves, continuously precipitated solid particles strongly erode metal surfaces. This mechanical abrasion removes protective films, exposing fresh metal to the corrosive medium and creating a vicious cycle of corrosion and wear that accelerates equipment damage

Acid Corrosion

Ammoniated brine contains a high concentration of chloride ions. Their strong penetration destroys passive films on metal surfaces, causing severe localized corrosion such as pitting and crevice corrosion

Lime-Milk Crystallization and Scaling

Lime-milk scaling is not simple physical adhesion, but a combined process of chemical conversion (carbonation), physical expansion (precipitation from supersaturation), and composite deposition. These deposits have high hardness, strong adhesion, and significant damage potential to protective linings, making them a major cause of unplanned shutdowns, equipment wear, and coating failure in chemical and environmental-protection systems

Equipment Hazards

Crystallization, sticking, and blockage: Crystals readily precipitate inside valves. Improper valve selection, especially flow passages with dead zones, allows rapid buildup, causing valve seizure, carbonation-tower level or pressure imbalance, and emergency shutdown of the entire production line

Erosive wear and internal leakage: Solid particles in the medium cause severe cutting wear on valve sealing surfaces. Once sealing fails, internal leakage can reduce system pressure, lower heavy soda ash conversion, disrupt process parameters, and trigger safety interlock shutdowns

Existing Valve Materials and Designs

Common onsite valves include PTFE-lined butterfly valves, metal hard-seated valves, and ceramic hemispherical valves

Problems with Existing Valves

The medium is highly corrosive and abrasive, with an operating temperature range of −19°C to 180°C. Certain locations require Leakage Class VI shutoff

Fluoropolymer-lined valves are traditionally used to address corrosion, but they have poor erosion resistance. When lime milk reacts with carbon dioxide in the air, calcium carbonate deposits are formed. These crystals, primarily calcite, have considerable mechanical strength (Mohs hardness approximately 3) and very strong adhesion, which can quickly seize valves and cause seal failure

Replacement Interval and Service Life

The typical replacement interval is only 2-3 months; under severe operating conditions, the usable life may be reduced to approximately 3-4 months

Losses Caused by Unplanned Shutdowns for Maintenance

In heavy soda ash (sodium bicarbonate) production, heavy soda ash suspension and ammoniated brine are two core process media. Their chemical corrosivity is not caused by a single strong acid or alkali, but results from the combined effects of complex chemical composition, physical state, and operating conditions

Soda ash production is a capital-intensive continuous-process industry. An unplanned shutdown can cause a sharp decline in current-period output and consume large amounts of steam and electricity during system reheating, repressurization, and commissioning, resulting in substantial economic losses

Superior Wear Resistance

Structural ceramics achieve a Rockwell hardness of over 87. Their wear resistance is approximately 266 times that of manganese steel and 172 times that of high-chromium cast iron, far exceeding that of conventional metals and PTFE-lined valves. They withstand long-term erosion and abrasion, preventing internal leakage and reducing replacement frequency

Excellent Corrosion Resistance

Structural ceramics are inorganic, non-metallic materials with extremely high chemical inertness. They resist corrosion from a wide range of acids, alkalis, and salts, including most acidic and alkaline media found in the salt-chemical industry

Smooth Surface & Low Adhesion

Structural ceramics provide self-lubricating and self-cleaning surface properties, effectively preventing material adhesion and buildup. With hardness of up to HRA 90, they withstand continuous erosion from powder media and ensure precise control of feed flow

Superior Process Quality

The high mechanical strength and smooth ceramic surface reduce crystal adhesion, blockage, and wear caused by ammonium and sodium salts, while making flushing more effective. Highly flat sealing surfaces allow the valve plug and seat to maintain uniform contact, preventing internal leakage and cross-contamination. Reliable sealing is maintained even after multiple production batches, improving the quality consistency of intermediate products