Material quality is one of the reasons that affect the life of mineral processing equipment
Material quality and heat treatment methods affect the service life of parts. The selection of parts materials should be based on the load nature and value of the parts, the speed of movement, the temperature, the lubrication conditions, the corrosion and the manufacturing process. It can be seen from experience that all wear and tear of mineral processing equipment begins with plastic deformation of the material. The wear resistance of the material is related to the material’s resistance to plastic deformation and the hardness of the material. For example, the wear resistance of carbon steels increases as the hardness and carbon content increase.
The high-hardness parts of the mineral processing equipment must have a high wear resistance under the required surface finish. When the surface finish is low, the protrusions are first rubbed off during the friction process to form hard abrasives to increase wear.
In addition to the high hardness, the parts of the mineral processing equipment that bear the impact load must also have good toughness. Due to the high brittleness of materials with high hardness, parts that are subjected to impact loads should not be selected from high-carbon steel, but should be low-carbon steel or alloy steel, and surface treatment.
The graphite in the cast iron has a lubricating effect. The wear resistance of the cast iron is high, and the voids of the graphite itself are also easy to penetrate the lubricant. Adding nickel, chromium, manganese, molybdenum and other alloying elements to cast iron and performing corresponding heat treatment can improve its strength and wear resistance. Chromium can increase the hardness, nickel can increase the hardness and promote graphitization, boron can produce a high hardness carbide in the cast iron structure, and the hardness increases with the increase of the boron content.
During the operation of the beneficiation equipment, the damage to the parts subjected to motion load is wear and fatigue. Many parts on the beneficiation equipment are subjected to bending alternating stress and other complex multi-directional stresses, and often produce cracks or even break due to fatigue. The occurrence of the initial crack of the part is related to the crystal structure, crystallization conditions and processing conditions of the metal itself. Different processing conditions make the metal crystals non-uniform, and the materials have different ability to withstand external forces; crystals under unfavorable conditions produce extreme stress and plastic deformation under the action of external forces, and micro cracks first appear in weak links.
In the actual assembly and maintenance process, in order to improve the fatigue resistance of parts, surface hardening treatments such as rolling strengthening and carburization are often used. For example, using the rolling method to strengthen the crankshaft journal fillet can improve the surface finish, cause preload, greatly reduce some of the peak tensile stress generated during use, and improve the fatigue resistance of the crankshaft. The fatigue strength can be effectively improved by strengthening the surface metal structure, such as surface high frequency quenching, quenching the crankshaft fillet, to improve the ability of mineral processing equipment parts to resist plastic deformation, and fundamentally improve the fatigue strength of mineral processing equipment parts.