The corrosion resistance design of wear plates for mining equipment in humid mine environments requires comprehensive considerations, including material selection, surface treatment, structural optimization, and process control, to address the combined effects of high humidity, acidic or alkaline water, mechanical wear, and electrochemical corrosion.
Material selection is the foundation of corrosion resistance design. While traditional high-manganese steel offers excellent toughness, insufficient impact in humid mines can lead to insufficient work hardening, resulting in an imbalance between wear resistance and corrosion resistance. Medium- and high-carbon low-alloy steels also suffer from insufficient toughness and limited corrosion resistance. The current mainstream approach favors low-carbon high-alloy steel or high-chromium cast iron. Chromium significantly improves the steel's hardenability and corrosion resistance by forming a dense oxide film that blocks the penetration of corrosive media. For example, steel grades with a chromium content exceeding 12% exhibit significantly improved corrosion resistance in acidic mine water. Furthermore, the addition of elements such as molybdenum and nickel further enhances pitting resistance. Furthermore, non-metallic materials such as polyurethane and ultra-high molecular weight polyethylene, due to their acid and alkali resistance and aging resistance, are becoming alternatives in humid environments, particularly for low-load scenarios.
Surface treatment technology is a key barrier against corrosive media. Thermally sprayed aluminum- or zinc-based alloy coatings form a sacrificial anodic protective layer on the surface of wear plates. When the coating is locally damaged, the aluminum or zinc corrodes preferentially, delaying the failure of the substrate. Surface hardening processes such as carburizing and nitriding increase the carbon and nitrogen content on the surface, improving hardness and corrosion resistance and making them suitable for high-load conditions. Electroplated or electroless nickel-phosphorus alloy coatings, with their non-porous and acid- and alkali-resistant properties, effectively isolate chloride and sulfur ions from mine water. For non-metallic wear plates, coatings with polyurethane elastomers or epoxy resins enhance wear and tear resistance while preventing water penetration.
Structural design requires a balance between corrosion resistance and mechanical strength. Wear plates in mines are often subjected to ore impact and equipment vibration, so structural design must avoid stress concentration that causes crack propagation. For example, using rounded corners instead of right-angle joints can reduce the corrosion tendency of the weld heat-affected zone. Optimizing plate thickness and rib layout can enhance overall rigidity while reducing the risk of corrosive media retention. For composite wear plates, such as those bonded to a metal substrate and rubber layer, the adhesive's water resistance and aging resistance must be ensured to prevent localized corrosion caused by interfacial delamination.
Sealing and drainage design are key to preventing water accumulation corrosion. Water accumulation often causes localized immersion of wear plates in mine equipment, accelerating the corrosion process. During design, drainage grooves or diversion holes should be provided around the wear plates to guide water out quickly. Sealant or rubber gaskets should be used to seal gaps between the plates to block water penetration. For example, by optimizing the trough angle and drainage structure, wear plates in the middle trough of a scraper conveyor can minimize water accumulation and significantly reduce corrosion rates.
Electrochemical protection technology can specifically inhibit corrosion reactions. For metal wear plates, the sacrificial anode method involves connecting a more active metal (such as magnesium or zinc) to preferentially dissolve the anode, protecting the cathode (wear plates) from corrosion. Impressed current cathodic protection uses a DC power supply to apply a negative potential to the wear plates, forcing electrochemical corrosion suppression. These technologies require adjusting the protection current density based on mine environmental parameters (such as resistivity and oxygen content) to avoid the risk of hydrogen embrittlement caused by overprotection. Regular maintenance and monitoring are crucial to ensuring design implementation. Mine wear plates require a regular inspection system, monitoring corrosion levels through techniques like ultrasonic thickness measurement and electrochemical impedance spectroscopy, and promptly replacing or repairing severely corroded areas. Mine water quality parameters (such as pH and chloride ion content) and equipment operating data should be recorded to inform wear plate selection and design optimization.
The corrosion-resistant design of wear plates for mining machinery accessories must be grounded in materials science, integrating surface engineering, structural mechanics, and electrochemistry to create a comprehensive solution from material selection to maintenance. This multi-technology collaboration can significantly extend the service life of wear plates in humid mine environments, reduce the risk of equipment downtime and maintenance costs, and provide reliable assurance for safe mine production.
