Crushing machinery includes jaw crushers, impact crushers, vertical impact crushers, hydraulic cone crushers, ring hammer crushers, hammer crushers, roller crushers, compound crushers, cone crushers, double-stage crushers, gyratory crushers, and mobile crushers, among others. Crushers typically handle larger pieces of material with coarser product particle sizes, usually greater than 8 millimeters. Their structural characteristic is that the crushing parts have a certain gap between them, not contacting each other. Crushers can also be divided into coarse crushers, medium crushers, and fine crushers. Generally, ball mills process finer materials with finer product particle sizes, reaching down to 0.074 millimeters, or even finer. Their structural characteristic is that the crushing components (or medium) come into contact with each other, using media such as steel balls, steel bars, gravel, or ore pieces. However, some machines are designed to perform both crushing and grinding functions, such as self-grinding mills. A ∮5.5×1.8-meter self-grinding mill can process ore particles up to 350-400 millimeters.