Full definition
A Jaw Crusher is the primary size reduction machine used in mining and quarrying operations, effectively breaking down run-of-mine rock into smaller sizes. This process is achieved through compression between two heavy steel jaw plates: one fixed and the other oscillating on an eccentric shaft. The toggle mechanism is critical as it converts rotary motion from the electric motor into a reciprocating crushing stroke, allowing the material to be crushed between the moving and stationary jaws. The feed opening size ranges from 400×600 mm for smaller applications to 1,600×2,100 mm for large-scale mining operations, illustrating the versatility of jaw crushers for various material sizes and types.
The capacity of jaw crushers can vary significantly, ranging from 50 tons per hour (t/h) for smaller models to over 2,000 t/h for larger, industrial units. This capacity is influenced by several factors including the material type, size, and the machine's operational settings. The typical crushing ratio is between 4:1 to 8:1, meaning that for every 4 to 8 units of raw material, 1 unit of crushed material is produced. The adjustment of the closed-side setting (CSS), which can be done via shimming or hydraulic cylinders, allows for control over the size of the output material, providing flexibility in various operations.
Jaw plates in these crushers are commonly made of high-manganese austenitic steel, known for its durability and ability to work-harden under impact. The composition of these jaw plates typically contains 12-22% manganese, resulting in hardness levels that can exceed 500 HBN. There are two main types of jaw crushers: single-toggle and double-toggle. Single-toggle crushers are simpler and more common, providing higher throughput, while double-toggle crushers offer more compressive force and are suited for very hard rock applications. The power requirements for jaw crushers range from 30 kW to 400 kW, depending on the size and capacity of the machine. In addition to the crushing mechanism, rubber components such as feed hopper linings and discharge chute linings are also crucial for protecting against impact and wear, with typical materials including natural rubber (NR). Brands like Metso Outotec, Sandvik, and FLSmidth lead the market with their advanced jaw crusher designs.