Crushing plants must be designed for ease of access and maintainability if they are to meet their production goals. Keeping maintenance requirements to a minimum helps achieve higher overall operating availability. Scheduled preventive maintenance at crushing plants involves a number of elements, including:
• Crusher wear parts • screen decks • feeder wear parts • conveyor skirting and adjustment • Oil and lubrication • Conveyor belt repair • Visual inspections • Electrical and instrumentation adjustments.
Provisions must be made for overhead cranes to remove and replace crusher wear parts. Supports must be provided for gyratory and conveyor main shafts and laydown space for the cone crusher bowls is essential. Some operators carry a complete spare screen and change out for major screen maintenance. Trolleys, jib cranes and pull points should be designed to facilitate equipment maintenance. Oil and lubrication systems should be centralized and designed for easy automatic changes, with provisions for well-ventilated centralized lubrication rooms where possible. (e.g., a line of fine cone crushers should have a central oil receiving area, with piping to and from each crusher lube package for quick and easy oil changes.)
Conveyor head chutes should be designed for easy access (not just through an inspection door, but through a man door in the chute). Conveyor belt change areas should be provided. Maintenance personnel should have easy visual and rapid access to screen decks for panel replacement. Designers should work with the screen manufacturers to ensure that covers provide good access for working on screens. Screening facilities must meet rigid dust emission requirements, but many off-the-shelf screen dust covers have not kept pace with these requirements. It may be necessary to custom-design covers that minimize emissions and provide easy access to the screen.
Building for cold-weather operations is very challenging, as is designing a plant in a desert environment. This is particularly true when year-round operation is required. Seasonal variations can change ore moisture content, so the crushing plant must be adaptable to changes in the material flow characteristics. Higher moisture requires greater angles of withdrawal, and stoneboxes must be designed to avoid plugging. The crushing plant equipment itself must be adjustable to climatic changes; for example, screen decks must be designed to maintain production, possibly by using wire mesh during the wet season and plastic during the dry. (Vary screen deck types dependent on seasons and material characteristics to achieve maximum passing through deck openings.
Climate also dictates the type of plant enclosures required as shown in Figures 1 and 2. Many crushers in milder weather climates or desert areas are installed with an open face and have no enclosures at all.