Desliming is a mineral processing operation that removes fine-grained particles — commonly referred to as slimes — from an ore slurry prior to downstream processing stages such as gravity separation, flotation, or leaching. Slimes are typically defined as particles finer than 38 microns (micrometers) or, in some cases, finer than 75 microns, depending on the specific processing circuit and ore type. Effective desliming is a critical step in the beneficiation of bauxite, gold, iron ore, and diamond ores, where the presence of excessive fines can significantly impair the efficiency and selectivity of downstream separation processes. Desliming is accomplished using hydrocyclones, spiral classifiers, thickeners, or combinations thereof. Hydrocyclones are the most widely used desliming devices in modern mineral processing plants because they offer high throughput capacity, low capital cost, and the ability to make sharp size separations at relatively fine cut points. By directing the ore slurry through a cyclone body under pressure, centrifugal forces separate fine slime particles (which report to the overflow) from coarser particles (which report to the underflow and proceed to further processing). In iron ore processing, desliming removes fine clay minerals that would otherwise reduce the efficiency of magnetic separation or flotation circuits, impair pellet quality, or increase reagent consumption. In gold ore processing, desliming ahead of gravity circuits reduces the loss of fine gold particles trapped in slime fractions, improving gravity recovery. In diamond processing, desliming removes fine clay-rich material that can blind screens, reduce separation efficiency in dense medium circuits, and reduce X-ray transmission recoveries. In bauxite processing, desliming removes fine gibbsite and clay-mineral particles that complicate downstream hydrocyclone classification and Bayer Process digestion.
