The influence of wet crushing conditions in mines on the wear mechanism of conical broken lining plates and analysis of suitable material selection

Under wet crushing conditions with high moisture content (usually referring to surface moisture>3-5%), there is a significant difference in the wear environment of the cone crusher liner compared to dry crushing. The intervention of moisture not only changes the physical properties of the material, but also introduces electrochemical corrosion, making the wear mechanism more complex. This puts forward unique comprehensive requirements for the performance of its wear-resistant materials.

1、 Composite wear mechanism under wet working conditions

In wet crushing, the lining plate is subjected to a composite damage caused by the synergistic effects of abrasive wear, corrosion, and high stress erosion, and its severity is often higher than that under simple dry conditions.

Aggravation of abrasive wear: failure of material cushion effect and lubrication erosion

Damage to the protective layer of the material cushion: In ideal dry crushing, fine particle materials can form a relatively stable "material cushion" on the surface of the lining plate, partially buffering the direct impact and cutting of large materials on the lining plate. Under wet conditions, water flow will wash away these fine particles, making it difficult to form or very unstable for the material pad, resulting in more exposure of the lining metal surface to direct impact and micro cutting of coarse particle materials.

Water wedge and lubrication effect: Water reduces the friction coefficient between materials and lining plates, as well as between material particles. This may cause some materials to slide inside the crushing chamber instead of being effectively crushed, and instead exacerbate the sliding friction and wear on the surface of the lining plate. At the same time, water infiltrates micro cracks under high pressure, creating a "water wedge effect" that may accelerate the propagation of fatigue cracks.

Introduction of Electrochemical Corrosion and Corrosion Wear Synergistic Effect

Formation of primary cells: Microscopic primary cells are formed in the electrolyte (water) due to potential differences between different phases of the lining material (such as austenite matrix and carbides) and between new and old surfaces, leading to electrochemical corrosion.

Synergistic effect: This is the most fundamental destructive mechanism in wet working conditions. Mechanical wear (abrasive cutting) continuously removes the passivation layer or corrosion products on the surface of the lining plate, exposing fresh and active metal substrates, thereby accelerating the corrosion process. On the contrary, corrosion weakens the grain boundaries on the metal surface, forms pits or loose layers, making the material easier to remove in subsequent mechanical wear. The synergistic effect of corrosion wear results in a much higher material loss rate than the simple combination of corrosion and wear alone.

High stress mud erosion and wear

When the mixture containing cement passes through the crushing chamber under high pressure, especially in the parallel zone, it will form high-speed mud erosion on the surface of the lining plate. Among them, hard abrasive particles are carried by water and continuously cut the metal surface.

2、 Special performance requirements for lining material

Based on the above mechanism, the lining material suitable for wet working conditions needs to enhance the following properties in addition to traditional wear resistance:

High corrosion resistance: This is the primary requirement that distinguishes it from dry process selection. The material must be able to effectively resist electrochemical corrosion to block the starting point of the "corrosion wear" synergistic effect chain.

The balance between high hardness and high toughness in corrosive environments: In corrosive environments, structures with high hardness but containing a large amount of continuous network carbides (such as primary carbides in some high chromium cast iron) are prone to corrosion, and the phase boundary between carbides and the matrix becomes a preferred channel for corrosion, leading to carbide detachment. Therefore, the material needs to have a uniform and dispersed hard phase distribution, and the substrate should have sufficient corrosion resistance.

Uniformity and density of organization: Loose, segregated, coarse-grained, or cast defective organization can form a "fast track" for corrosion and weak areas for wear. A dense and uniform organization can provide more consistent protection.

3、 Material selection suggestions and technical paths

1. Improvement of applicability of high chromium cast iron (Cr15-Cr26) materials

Analysis: High chromium cast iron (such as Cr20, Cr26) can form a dense Cr ₂ O Ⅲ passivation film on the surface due to its high chromium content, and its corrosion resistance is significantly better than high manganese steel and most medium low alloy steels. The high volume fraction (>20%) of (Cr, Fe) ₇ C3 carbides has high hardness and discontinuous distribution, providing good anti-wear ability.

Applicable components and considerations: Especially suitable for areas that are subjected to strong mud erosion and grinding, such as the lower part of the fixed cone rolling bowl wall and the parallel area of the dynamic cone crushing wall. It should be noted that its toughness is lower than that of high manganese steel. When the feeding is uneven or there is a risk of iron overload, its fracture safety should be evaluated, or a composite design with a ductile matrix should be considered.

2. Limitations and countermeasures of the application of high manganese steel (such as Mn18Cr2)

Analysis: The corrosion resistance of high manganese steel (austenitic structure) in static water is still acceptable, but under dynamic conditions of severe impact and continuous exposure of fresh surfaces due to wear, its passive film cannot form stably, and its corrosion resistance advantage is not obvious. And its dependence on impact hardening characteristics may not be fully stimulated when the wet material cushion effect weakens.

Application suggestion: If high manganese steel is selected, special attention should be paid to adding alloying elements that improve corrosion resistance, such as increasing the content of chromium (Cr) and molybdenum (Mo) appropriately, and ensuring standardized water toughening treatment to obtain a single austenite structure that is as uniform and dense as possible.

3. Intermediate route of multi-element alloy steel

Analysis: By reasonably adjusting alloy elements such as chromium (Cr), nickel (Ni), molybdenum (Mo), copper (Cu), etc., alloy steel with certain toughness, high hardness, and improved corrosion resistance can be obtained. Its performance is between high manganese steel and high chromium cast iron, suitable for wet crushing under conditions that are not extremely harsh.

Consideration: It is necessary to obtain a matrix structure with relatively good corrosion resistance such as tempered martensite or bainite through heat treatment, and control the morphology of carbides.

4. The application value of composite material technology

Analysis: The use of bimetallic composite casting (such as high toughness steel matrix+high chromium cast iron wear-resistant layer) or surface cladding technology can obtain a high hardness and high corrosion resistance wear-resistant layer on the working surface while ensuring the overall toughness and strength of the component. It is one of the effective technical paths to deal with complex wet working conditions.

4、 System process coordination beyond materials

Material selection must be combined with process adjustments to achieve optimal results

Optimize feeding and drainage: minimize the moisture content of the feed as much as possible; Ensure smooth discharge of material from the bottom of the crusher without any accumulated water.

Maintain continuous full chamber feeding: Even under wet conditions, efforts should be made to maintain a stable layer of material to utilize the material itself to slow down the water flow and directly flush the lining plate.

Targeted lubrication: Consider using lubricants with certain rust prevention functions and prevent water from entering the lubrication system.

Conclusion

The requirements of wet crushing conditions for conical broken lining plates have shifted from resisting mechanical wear to resisting "mechanical chemical" composite damage. Under these conditions, the synergistic performance of corrosion resistance and wear resistance of the material becomes the priority consideration indicator for selection.

High chromium cast iron materials have relatively outstanding applicability in such working conditions due to their inherent high chromium content, which enhances their corrosion resistance, especially in areas with strong erosion and grinding. Traditional high manganese steel needs to be improved through alloying to compensate for its lack of dynamic corrosion resistance. The final material decision should be based on a comprehensive evaluation of the corrosiveness (such as pH value), moisture content, and impact load size of the specific material, combined with analysis of equipment operating conditions. At the same time, it must be recognized that there is no single material solution applicable to all wet process conditions, and reasonable process operations are crucial for extending the life of any material lining.