Chloride-resistant (KIDD) Stainless Steel Cathode Plate

Chloride-resistant (KIDD) stainless steel cathode plates represent a key technological advancement in hydrometallurgical electrolysis, particularly copper electrolysis. The core of this advancement lies in the use of high-performance duplex stainless steel materials to address the industry pain point of accelerated corrosion in traditional cathode plates under high-chloride-ion electrolysis environments.

1. Technical Background and Industry Needs

During electrolysis, the unavoidable presence of chloride ions (Cl⁻) in the electrolyte is a primary cause of pitting corrosion, crevice corrosion, and stress corrosion cracking in stainless steel cathode plates. Chloride ions damage the passivation film on the stainless steel surface and form localized corrosion pits, severely impacting the flatness, service life, and quality of precipitated metals (such as cathode copper).

2. Material Upgrade Path: From 316L to Duplex Stainless Steel S32205 (2205)

Traditional Solution (316L austenitic stainless steel):

Suitable for mild environments with low chloride ion content (typically < 35 ppm).

Limitations: Once the chloride ion concentration exceeds 35 ppm, the pitting resistance of 316L decreases significantly, the corrosion rate accelerates, leading to pitting and cratering on the plate surface, shortening its service life and increasing maintenance costs.

Technical Alliance: Jointly developed by AATI and TISCO (Taiyuan Iron & Steel Group Co., Ltd., a leading stainless steel manufacturer in China).

Material Properties: Grade S32205 (UNS S32205, corresponding to the Chinese grade 022Cr22Ni5Mo3N, commonly referred to as 2205 duplex steel).

 

 

 

 

Duplex Structure: The microstructure consists of approximately 50% austenite and 50% ferrite phases. The two phases complement each other, combining the toughness of austenitic steel with the strength of ferritic steel.

High Strength: The yield strength is nearly twice that of 316L, making the cathode plate more robust and less prone to deformation, which is beneficial for achieving larger sizes and longer service life designs.

Superior Chloride Ion Corrosion Resistance: Thanks to its high chromium (Cr), molybdenum (Mo), and nitrogen (N) content, its Precious Metallization Equivalent (PREN) value is significantly higher than that of 316L, allowing it to withstand harsh environments with chloride ion concentrations reaching hundreds or even thousands of ppm, effectively inhibiting pitting and stress corrosion.

Rigorous Testing: This chloride ion-resistant KIDD cathode plate, made of S32205 duplex stainless steel, has passed rigorous industrial testing experiments in large-scale electrolysis plants.

Performance Verification: Test results confirm its excellent corrosion resistance and structural stability in high-chloride ion electrolytes, maintaining the integrity of the plate surface and significantly extending its service life.

Wide Application: Given its superior performance, this product has moved from the testing phase to mass application and promotion, and is gradually replacing traditional 316L cathode plates in high-requirement electrolysis projects worldwide, becoming the new standard solution for electrolysis operations in high-chloride ion environments.