Black Liquor Screen Basket Material Selection: 304/316L/Duplex Steel for Different Pulping Processes

Introduction
Selecting the right material for black liquor screen baskets is the cornerstone of ensuring long service life, low maintenance costs and high screening efficiency in pulp mill black liquor treatment. The wrong material choice will lead to rapid wear, corrosion or deformation of the screen basket-especially for EB Drilled Screen Baskets, whose high-precision electron beam drilling holes rely on the original performance of the base material to exert screening advantages.
Black liquor contains alkali, sulfide, chloride and other corrosive media, and the pulp friction during screening will also cause abrasive damage to the screen basket. Combined with different pulping processes (kraft, mechanical, recycled paper, etc.), the composition and corrosivity of black liquor vary greatly. This article will detail the performance of 304/316L stainless steel and duplex steel, and match the most suitable material solutions for different pulping processes, especially for the material selection of high-precision EB Drilled Screen Baskets.
Key Material Performance Comparison for Black Liquor Screen Baskets
The three mainstream materials for industrial black liquor screen baskets (including EB Drilled Screen Baskets) are 304 stainless steel, 316L stainless steel and duplex steel. Their corrosion resistance, wear resistance and cost performance are quite different, and the matching scenarios are clear:
304 Stainless Steel:Good mechanical strength, easy processing, stable performance Resists mild alkali corrosion; general wear resistance Low Low-corrosivity black liquor system.

316L Stainless Steel: Molybdenum added, excellent pitting corrosion resistance Resists medium-high alkali/sulfide corrosion; better wear resistance than 304 Medium Medium-corrosivity black liquor, low sulfur pulping.

Duplex Steel (2205/2507): Dual-phase structure, high strength + high corrosion resistance,Resists high alkali/sulfur/chloride corrosion; excellent wear resistance High,High-corrosivity black liquor, heavy-duty screening.

Important Note for EB Drilled Screen Baskets: Electron beam drilling is a cold working process that does not damage the original metallographic structure of the base material. Unlike laser drilling, it will not cause thermal deformation or material performance degradation of the screen basket-this makes the EB Drilled Screen Basket can fully exert the corrosion and wear resistance of the selected base material, and the service life is 30%-50% longer than the ordinary processed screen basket of the same material.
Material Selection for EB Drilled Screen Baskets Based on Different Pulping Processes
The composition of black liquor is determined by the pulping process, which is the core basis for selecting the material of EB Drilled Screen Baskets. The following is the targeted material matching plan for the four most common pulping processes in the industry:
1. Kraft Pulping (Sulfate Pulping)
Black Liquor Characteristic: High alkali content, high sulfide concentration, strong corrosivity; serious pulp friction during screening.
Recommended Material: Duplex Steel (2205/2507) → EB Drilled Screen Baskets made of duplex steel can resist the high corrosion of sulfur-containing black liquor and the heavy wear of kraft pulp, which is the best choice for large-scale kraft pulp mills.
Alternative: 316L stainless steel (for small and medium-sized mills with low sulfur pulping and reduced production load).
2. Mechanical Pulping (MP/TMP)
Black Liquor Characteristic: Low alkali content, mild corrosivity; high fiber content, strong abrasive wear on screen basket.
Recommended Material: 304 Stainless Steel → EB Drilled Screen Baskets of 304 stainless steel have high cost performance, and the cold working of EB drilling maintains the mechanical strength of 304, which can effectively resist the abrasive wear of mechanical pulp.
3. Recycled Paper Pulping
Black Liquor Characteristic: Complex composition, containing chloride, ink residue and other impurities; local pitting corrosion is easy to occur on the screen basket.
Recommended Material: 316L Stainless Steel → The molybdenum element in 316L can effectively resist pitting corrosion caused by chloride, and the high-precision holes of EB Drilled Screen Baskets can avoid impurity blockage while ensuring screening efficiency.
4. Semi-Chemical Pulping
Black Liquor Characteristic: Moderate alkali content, low sulfide; balanced corrosion and wear.
Recommended Material: 316L Stainless Steel → A perfect balance of cost and performance, the EB Drilled Screen Baskets of this material can adapt to the medium load screening of semi-chemical pulping, and the service life is significantly longer than ordinary screen baskets.
Practical Material Selection Tips for EB Drilled Screen Baskets
Prioritize the corrosive medium content (sulfur, chloride, alkali concentration) of black liquor, not just the pulping process-test the black liquor components regularly and adjust the screen basket material in time.
For custom EB Drilled Screen Baskets, inform the supplier of the production load (screening capacity per hour) while providing the pulping process, and the supplier can optimize the material thickness and hole distribution design.
For pulp mills with mixed pulping processes, choose 316L stainless steel or duplex steel for EB Drilled Screen Baskets to ensure adaptability to different black liquor characteristics.
The surface coating (e.g., ceramic coating) can be matched on the basis of the base material, which further improves the wear resistance of the EB Drilled Screen Basket (suitable for heavy-duty screening scenarios).
Conclusion
The material selection of black liquor screen baskets is not a one-size-fits-all solution, and the EB Drilled Screen Basket, as a high-precision screening component, has higher requirements for the base material-only by matching the material with the pulping process and black liquor characteristics can the advantages of EB drilling's high precision, high consistency and long life be fully exerted.
Whether it is the low-cost 304 stainless steel, the balanced 316L stainless steel or the high-performance duplex steel, the rational selection can effectively reduce the replacement frequency of the screen basket, lower the maintenance cost of the pulp mill, and improve the overall efficiency of the black liquor treatment system.

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Hebei Province,China

Hebei SLOT Filter Technology Co., Ltd.​ Global leader in industrial screening & separation solutions. With ISO 9001/SGS certifications and 15+ years of expertise, we engineer precision screening systems through proprietary ​​wedge wire forming​​ and ​​polyurethane casting technologies​​.
SLOT's technology has been successfully applied in over 30 countries around the world and is widely used in numerous fields such as papermaking, petrochemicals, fine paper chemicals, energy and power, water treatment, automotive manufacturing, mining, food and beverage, and metal processing.

This release was published on openPR.