Ceramic Valve Solutions for Salt Chemical Thickeners

Chemical Corrosion

The medium contains relatively high concentrations of chloride ions (Cl⁻), organic acids, heavy metals, and other corrosive substances. Under high-salinity conditions, typically 3%-8% or even higher, conventional carbon steel and standard stainless-steel equipment are highly susceptible to severe chloride-induced pitting and stress-corrosion cracking

Physical Abrasion

The medium contains large quantities of hard solid particles, such as silica and carbonates. During high-velocity flow and pumping, these particles continuously erode pipelines, valves, pump bodies, and other flow-path components. Materials with high hardness and excellent wear resistance are normally required

High Viscosity with a Strong Tendency to Crystallize and Block

The medium is a high-viscosity paste. During dehydration or drying, evaporation of water causes the material to enter a plastic state, sharply increasing surface adhesion and allowing the material to accumulate on production equipment

Crystallization and Scaling

Scaling is not caused merely by physical adhesion. It results from the combined effects of chemical conversion through carbonation, physical expansion caused by supersaturation and precipitation, and composite fouling. This mechanism develops rapidly and generates intense expansive stress, making it a major cause of frequent unplanned shutdowns, equipment wear, and failure of protective coatings in the chlor-alkali and environmental-treatment sectors

Equipment Hazards

The medium is mildly alkaline and readily absorbs carbon dioxide (CO₂) from the air or process gas, triggering carbonation and producing calcium carbonate precipitates. These deposits have relatively high mechanical strength, approximately Mohs 3, and strong adhesion

Engineering Hazards: During shutdowns, calcium carbonate can crystallize within pipelines, valve clearances, and micropores in protective coatings, forming dense, hard scale. This progressively reduces the internal flow diameter or can completely seize the equipment. Volumetric expansion during crystallization may also crack and detach protective coatings, compromising equipment sealing integrity

Existing Valve Materials and Types

Commonly used valves include butterfly valves made of cast iron, HT200 gray cast iron, or WCB cast steel; metal hard-seated ball and globe valves with WCB bodies; and conventional rubber-lined butterfly valves using natural or hard-rubber linings

Problems with Existing Valves

• External leakage: Corrosion may perforate the valve body, while packing failure allows brine or lime slurry to escape
• Internal leakage: Incomplete valve shutoff allows thickener underflow slurry to enter the clarified-overflow line, increasing downstream brine turbidity
• Operating failure: Crystallized scale causes the valve to stick and prevents opening or closing, often requiring manual hammering on site
• Frequent blockage: Drain valves become obstructed, preventing proper discharge and causing excessive sludge loading at the thickener cone bottom and overloading the rake mechanism

Replacement Cycle and Service Life of Existing Valves

Valves handling thickener underflow slurry typically last only 3-6 months, while valves in clarified-overflow pipelines generally last 8-12 months. Frequent maintenance and replacement result in high operating costs. Valve failure may cause turbid overflow from the thickener and allow salt sludge to enter the purified-brine system, directly affecting the stability of brine purification, the critical front-end process

Losses Caused by Unplanned Shutdown Maintenance

• Direct maintenance costs: Emergency spare-parts procurement, urgent labor, system cleaning, and disposal of hardened deposits
• Production-capacity losses: As brine purification is the upstream process, valve failure may force load reduction or shutdown. Additional time is required after maintenance to restore brine-feed capacity, directly reducing soda ash output
• Material and energy losses: Crystallized salt and ammonia-containing materials may be scrapped, while steam and electricity continue to be consumed ineffectively during shutdowns
• Downstream process losses: Turbid thickener overflow allows calcium and magnesium impurities to pass downstream, causing scaling in distillation columns and pipelines, accelerating corrosion and abrasion, and increasing ammonia and steam consumption
• Safety and environmental losses: Media leakage creates safety hazards, increases solid-waste and wastewater-treatment volumes, and disrupts production schedules

Superior Wear Resistance

Structural ceramics achieve a hardness above HRA 87, providing approximately 266 times the wear resistance of manganese steel and 172 times that of high-chromium cast iron. Their exceptional hardness withstands the continuous erosion and abrasion of solid particles, prevents media leakage, and substantially reduces valve replacement frequency

Excellent Corrosion Resistance

Structural ceramics are inorganic, non-metallic materials with exceptional chemical inertness. They resist corrosion from acids, alkalis, chlorides, and other salts, making them suitable for most corrosive media encountered in chlor-alkali and soda ash plants

Smooth Surface and Low Adhesion

Structural ceramics possess inherent lubricity and self-cleaning surface properties, effectively reducing material adhesion and accumulation. Their hardness of up to HRA 90 withstands continuous particle erosion and helps maintain precise feed-flow control

Improved Process Quality

The high mechanical strength and smooth surface of structural ceramics reduce the adhesion, abrasion, crystallization, and scaling of calcium and magnesium salts. Highly precise sealing surfaces provide close contact between the valve ball and seats, preventing media leakage. Even after prolonged operation, the valve can maintain reliable sealing and improve product quality consistency between production batches