Among the numerous inorganic salt products in the chemical industry, Sodium sulfate Na ₂ SO ₄ ) is a widely used basic chemical raw material. Whether in detergents, glass production, papermaking, textile printing and dyeing, pharmaceuticals, or the manufacturing of electronic-grade materials, sodium sulfate plays a crucial role.
However, in the industrial production process, efficiently purifying sodium sulfate crystals from solutions or reaction slurries is essential. , it has always been a craft task that combines both challenge and criticality. During the filtration process, “ Separation efficiency ““ Filter cake purity ““ Equipment Stability ” With “ Washing and Regeneration ” , jointly determining the operational costs and product quality of the entire production line.

In this process, the horizontal vacuum belt filter ( Horizontal Vacuum Belt Filter, HVBF ）With its features of continuity, controllability, and high automation, it has become a crucial solid-liquid separation device in the sodium sulfate purification process. Meanwhile, among the core components of this equipment, the performance and structural design of the filter belt (filter cloth) directly determine the efficiency of the purification process. “ Balancing Precision and Efficiency ”。

I. Process Challenges in Filtering Chemical Sodium Sulfate

The complexity of purifying and filtering sodium sulfate stems from both the material properties of the substance and the stringent requirements of the production environment.

1. Particles are fine and unevenly distributed.
   The particle size of sodium sulfate crystals typically ranges from 20 to 200 Between micrometers, some areas have a higher content of fine grains, making it extremely easy for them to form on the surface of the filter cloth. “ Secondary filtration layer ” , leading to a decline in flux.
   
2. The mother liquor has high viscosity and contains many impurities.
   The production process often generates by-products or impurity ions, such as magnesium sulfate and sodium chloride, resulting in a liquid with relatively high viscosity, which places greater demands on the hydrophilic/hydrophobic properties of the filter cloth.
   
3. The process features strong continuity and a long operational cycle.
   Horizontal vacuum belt filters typically operate continuously, working every day. 10~20 More than an hour. The filter cloth needs to be maintained over the long term. Dimensional stability, wrinkle resistance, and excellent liquid drainage performance To avoid unstable operation or downtime for replacement.
   
4. Regeneration cleaning demands high standards.
   When filtering sodium sulfate solution, crystals tend to deposit and form scale within the fabric pores. If cleaning is incomplete, this can lead to flux decline, reduced vacuum efficiency, and increased energy consumption.
   

Therefore, the filter cloth suitable for sodium sulfate purification must combine high retention accuracy, stable liquid drainage channels, an easily detachable surface, and excellent regenerative properties.

II. The Working Principle of Horizontal Vacuum Belt Filter

A horizontal vacuum belt filter is a type of Continuous Vacuum Filtration System , widely used in the separation and dewatering sections for materials such as inorganic salts, fertilizers, mineral slurries, and chemical intermediates.
Its core process includes:

• Material fabric : The slurry containing sodium sulfate crystals is evenly distributed across the running filter cloth;
• Vacuum Filtration :The lower vacuum system creates negative pressure, drawing out the liquid phase (mother liquor) while leaving the solid phase (crystals) behind on the filter cloth;
• Filter cake washing : A multi-stage spray system cleans the filter cake, removing impurity ions;
• Filter cake drying and discharging : Unloading is completed by air blowing, scraper, or belt stripping;
• Filter Cloth Cleaning and Regeneration : High-pressure water jets perform online cleaning of the filter cloth, ensuring long-term permeability.

In this continuous process, The filter cloth is a multifunctional media layer used for carrying, filtering, washing, and discharging materials. Not only does it affect filtration efficiency, but it also determines the washing and regeneration performance.

III. Optimization of the Mesh Belt Design for Sodium Sulfate Filtration

Drawing on years of practical experience in the chemical industry, Xiamen Citius has developed a high-performance filter belt specifically designed for horizontal vacuum belt filters, tailored to the crystal structure and liquid characteristics of sodium sulfate solutions. This innovative filter belt features the following remarkable structural attributes:

1.  The surface is smooth and flat, making the filter cake easy to peel off.

Mesh Belt Fabric The front features a longer warp node design. , forming a smooth, continuous surface; after the crystals form the filter cake, their contact area with the fabric decreases significantly, greatly reducing adhesion and enabling Cake filtration becomes smoother. This not only enhances unloading efficiency but also reduces scraper wear, thereby extending the equipment's lifespan.

2.  Reverse open pores to enhance drainage and cleaning.

The back of the fabric is designed as Open-type rectangular hole structure , the liquid flow channel is unobstructed, effectively accelerating the discharge rate of the mother liquor.
This dual-layer heterogeneous design enables the mesh belt to maintain sufficient retention accuracy while still delivering a high flux; meanwhile, the open structure allows cleaning water to penetrate deep into the fabric, ensuring thorough in-line regeneration.

3. “ Person ” Character shape organization ensures greater stability against creasing.

Traditional filter cloths tend to develop issues after prolonged operation. “ On sale ” Or “ Straying off course ” Phenomenon. Citiuss CITIUS Adopt Herringbone weaving structure , enabling the mesh belt to achieve greater stiffness and structural stability in the lateral direction.
This organizational structure can evenly distribute stress during both tensioning and operation. Avoid edge curling and localized fatigue. Thus maintaining excellent geometric stability and extending service life.

4.  High interception accuracy and excellent dimensional stability

The warp and weft densities, combined with the precisely engineered monofilament diameter, ensure a uniform filter cloth pore size distribution and stable filtration retention.
Even under repeated exposure to tension, temperature fluctuations, and vacuum negative pressure during long-term operation, dimensional changes can still be kept within an extremely narrow range, ensuring consistent filtration performance.

5.  Excellent hydrophobic and regenerative properties

Regarding the sodium sulfate crystallization process “ Solvent extraction - Crystallization - Extraction ” The characteristic is that the surface of the Citiuss mesh belt features Better hydrophobicity and anti-crystallization adhesion capability 。
The filter cloth can be easily cleaned after use with high-pressure water or steam, restoring its permeability and ensuring stable operation over extended periods, thereby significantly reducing maintenance and operational costs.

IV. Performance and Usage Results

In the continuous crystallization and purification unit for sodium sulfate, Citiuss is selected. CITIUS After using the dedicated horizontal vacuum belt filter cloth, user feedback indicates:

• Increased filtration rate 15~30% : Drainage is smooth, and vacuum utilization is improved;
• The moisture content of the filter cake decreases. 2~5% : Helps conserve energy consumption during subsequent drying processes;
• Filter cloth usage cycle extended 30% The above :The herringbone structure significantly enhances fatigue resistance;
• Regenerative cleaning delivers excellent results. : Flux can be restored to its original state after cleaning 90% The above;
• The filter cake is peeled off more cleanly. : Minimal surface crystal residue ensures a more stable discharge process.

These performance advantages directly enhance the economic benefits and operational reliability of the sodium sulfate production line.

V. Systematic Matching from Materials to Processes

In industrial applications, filter cloths are not standalone components—they are system elements deeply integrated with process conditions.
Citiusas CITIUS In the implementation of the sodium sulfate project, not only standard-model filter cloths will be provided, but also customized solutions tailored to the customer's needs. Crystal grain size distribution, mother liquor composition, vacuum level, and operating speed And other parameters for customized optimization.

Includes:

• Aperture and weave density adjustment;
• Seam design and edge encapsulation treatment;
• Surface coating, edge-trimming method, and antistatic treatment;
• Tension and misalignment tests for filter cloth lifespan.

This kind of Craft-level matching , ensuring that each filter cloth can deliver maximum performance in the on-site equipment.

Conclusion

The purification and filtration of sodium sulfate is not only a physical separation process but also a demonstration of “ Precision, Stability, and Durability ” The ultimate pursuit.
From every warp and weft thread in the fabric structure to each process curve governing the operation of the entire machine, Citiuss CITIUS Always leveraging rigorous engineering thinking and a spirit of innovation to deliver more reliable filtration solutions for the chemical industry.

On the production line where vacuum and crystallization intertwine, the presence of a high-performance filter cloth is quietly determining both the purity of the product and the efficiency of manufacturing. —— That's about filtration technology. “ Silent Power ” , also Citiuss CITIUS Three decades of dedication and perseverance in the field of industrial separation.