Against the backdrop of the ongoing transformation and upgrading of the phosphate chemical industry, the semi-hydrated wet-process phosphoric acid technology—thanks to its compact process flow, relatively low energy consumption, and higher phosphorus recovery rate—is gradually becoming a key focus for technological upgrades in the industry. Compared with the traditional dihydrate process, the semi-hydrated process exhibits distinct differences in crystal morphology, solid-liquid separation efficiency, and byproduct control. Among these factors, the filtration system is the critical component that determines the stability and economic viability of the entire production line.

In this system, the filter cloth is not merely... “ Consumables ” It is also a core material that directly affects the quality of phosphoric acid, the moisture content of phosphogypsum, equipment operating load, and production continuity. As a leading enterprise in China’s industrial filtration materials sector, Xiamen Xiadis Filter Materials Technology Co., Ltd. We have accumulated extensive practical experience in the R&D and engineering application of filter cloths specifically designed for semi-water phosphoric acid filtration, and we continue to provide phosphochemical enterprises with high-strength, wear-resistant, and customized system solutions.

I. Special Challenges Posed by the Semi-Water Wet-Process Phosphoric Acid Process to Filtration Systems

Half-water wet-process phosphoric acid HH In the reaction stage, hemihydrate calcium sulfate crystals are formed. These crystals typically exhibit a needle-like or columnar crystal structure, with a fine-grained morphology and relatively high hardness. Compared to the dihydrate process, the filtration stage faces the following challenges:

1.  Crystalline morphology causes greater wear on filter cloths.

The semi-crystalline structure has distinct edges and corners, which, when circulating at high speed in horizontal belt vacuum filters, rotary drum vacuum filters, or disc filtration equipment, continuously rub against and scour the surface of the filter cloth. If the filter cloth lacks sufficient strength, it is highly prone to wear, fuzzing, and even breakage.

2.  High-solid-content slurries have high requirements for permeability.

In the semi-water process, the slurry concentration is relatively high, and the particle size distribution of solid particles is broad. The filter cloth must not only ensure sufficient throughput but also effectively retain fine particles; otherwise, problems such as material leakage and turbid filtrate may occur.

3.  Long-term stability under strong acidic conditions

The wet-process phosphoric acid system contains high concentrations of free acids and impurity ions, requiring filter cloths to operate for extended periods in a highly corrosive environment. Therefore, dimensional stability and chemical resistance are critical.

4.  The difficulty of cake detachment increases.

Under certain conditions, the semi-crystalline material tends to form a dense filter cake layer. If the surface structure of the filter cloth is not designed appropriately, it can easily become clogged, thereby affecting the discharge process and the continuity of the production cycle.

For this very reason, polyester monofilament filter cloth specifically designed for phosphogypsum has become an important choice for the semi-hydrous process.

II. Structural Advantages and Performance Characteristics of Phosphogypsum Polyester Monofilament Filter Cloth

1.  Monofilament weaving structure —— Aperture stability and high wear resistance

The monofilament filter cloth features a regular warp-and-weft weaving structure with uniformly distributed pore sizes and a smooth, even fabric surface. Compared to multifilament structures, it exhibits superior resistance to fuzzing and maintains stable performance even under high-friction operating conditions.

In a semi-water-based continuous production environment, the monofilament structure can significantly reduce fiber breakage and pore blockage, thereby extending the overall service life.

2.  High-strength design —— Compatible with large-scale continuous equipment

Modern phosphate chemical production lines are typically equipped with large-scale horizontal vacuum belt filters, and the filter cloths must withstand prolonged tension and cyclic operation. The high-strength weaving structure endows these filter cloths with excellent tensile strength and dimensional stability, making them resistant to deformation even under heavy loads.

3.  Balancing Flux and Accuracy Control

Selecting filter cloth is not simply a matter of pursuing a specific pore size; rather, it requires a comprehensive match that takes into account factors such as crystal particle size distribution, slurry concentration, and vacuum negative pressure. Through precise weaving control, it’s possible to maintain high retention efficiency while simultaneously increasing the filtration flux per unit area and shortening the filtration cycle.

4.  Excellent filter cake release performance

The smooth surface structure of the monofilament reduces particle embedding, making the filter cake easier to detach, lowering the frequency of manual intervention, and enhancing the continuous operational efficiency of the equipment.

Three, from “ Standard product ” To “ Customized operating conditions ” The upgrade approach

The phosphate chemical industry exhibits significant operational variability: differences in ore sources, reaction temperatures, acid concentrations, and equipment designs all affect filtration performance. Consequently, a single standard filter cloth often falls short of meeting the requirements for long-term stable operation.

Xiamen Xiadis Filtration Materials Technology Co., Ltd. adheres to a customized approach centered on operating conditions:

• Analyze the solid content of the slurry and particle size distribution.
• Test requirements for the clarity of the filtrate
• Assess the operating tension and cycle frequency of the equipment.
• Match vacuum degree with washing intensity
• Optimize the filter cloth interface structure and installation method.

We also offer advanced processing services tailored to customer needs, including glue application for reinforcement, edge wrapping, heat-sealed edge finishing, and the installation of guide strips, ensuring that the filter cloth is highly compatible with your equipment.

4. Reduce the moisture content and enhance the comprehensive utilization value of phosphogypsum.

The current industry has shifted from “ Emission-oriented ” Gradual transition “ Resource-oriented utilization ” As a byproduct, the moisture content of phosphogypsum directly affects transportation costs and the efficiency of its subsequent utilization.

High-performance filter cloth plays a crucial role in this process:

• Improve primary dehydration efficiency
• Reduce the residual liquid content in the filter cake.
• Reduce subsequent drying energy consumption
• Improve the physical structural stability of gypsum

When the moisture content of the filter cake decreases, 1% At the same time, for large-scale manufacturing enterprises, this means significant savings in energy costs. Optimizing filter materials often leads to long-term improvements in overall efficiency.

V. Wear Resistance and Service Life: The True Core of Cost Control

In the semi-water process, frequent replacement of filter cloths not only increases material costs but also disrupts the production rhythm. Downtime for filter cloth replacement and subsequent re-tensioning and adjustment all lead to hidden losses.

In actual operation, the high-strength, wear-resistant polyester monofilament filter cloth exhibits:

• Tensile strength is stable.
• Even surface wear
• Slow degradation of filtration performance
• Extended usage cycle

Long-term operational data show that high-quality filter cloths can significantly reduce the consumables cost per unit of output and improve equipment utilization.

6. Domestic leading manufacturers continue to iterate their technologies.

As a leading enterprise in the research and manufacturing of technical fabrics for filtration materials (mesh belts), Xiamen Xiadis Filtration Materials Technology Co., Ltd. has long been dedicated to the R&D of industrial filtration systems, having developed a mature technological system in fields such as phosphate chemical industry, mining, metallurgy, and new energy.

In the application of semi-water wet-process phosphoric acid, the company continues to carry out:

• High-Performance Fabric Structure Optimization Experiment
• Upgraded Technology for Fine Control of Pore Size Distribution
• Research on Surface Anti-Aggregation Structures
• Long-term operational durability testing

Through continuous technological iteration, the filter cloth achieves more stable performance in terms of high strength, wear resistance, and corrosion resistance.

7. Future Trends: Green Manufacturing and Efficient Separation Going Hand in Hand

As environmental protection policies and energy-saving requirements continue to tighten, phosphate chemical enterprises are placing greater emphasis on the overall efficiency of their filtration systems. The future development trends of filter cloths will revolve around:

• Higher filtration throughput
• Lower filter cake moisture content
• Longer service life
• Enhanced corrosion resistance
• Higher compatibility with intelligent control systems

Material upgrades and equipment upgrades will create synergies, driving the semi-wet phosphoric acid process toward a higher-quality stage.

Conclusion

The stable operation of the semi-wet process for wet-process phosphoric acid production relies heavily on reliable filtration materials. Polyester monofilament filter cloth for phosphogypsum, with its advantages of high strength, excellent abrasion resistance, stable pore size, and smooth detachment, has become an essential tool for phosphate chemical enterprises to enhance efficiency and reduce costs.

Leveraging years of experience in industrial filtration and its customization capabilities, Xiamen Xiadis Filtration Materials Technology Co., Ltd. will continue to focus on optimizing operating conditions and upgrading technologies, providing the phosphate chemical industry with more professional, reliable, and stable filtration solutions, and helping enterprises steadily advance on the path toward green manufacturing and high-quality development.