īeneficiation and whitening of clays-Removal of sulfide and oxide iron.īeneficiation of bauxite to remove silica, calcite, and iron oxides.īeneficiation of iron ores to remove alumina, silica, kaolinite, phosphorous, and calcite.
Such microbially induced beneficiation will find applications in a number of areas such as: Microbially induced mineral beneficiation involves three strategies, namely, selective bioleaching of the undesirable mineral from an ore or concentrate, selective flotation of the mineral, or selective dispersion/flocculation. A combination of acid attack and grinding to disintegrate the fibers has been shown to produce a pulp more amenable to flotation ( Uddin et al., 2011). Processing fibrous ultramafic ores requires low solids percent in grinding and flotation. Processing Ni ores hosted in ultramafic rock (i.e., high in fibrous Mg, Fe silicates) is challenged by rheology. Phyllosilicate group minerals pose particular problems ( Ndlovu et al., 2014), especially fibrous serpentines which can form tangled mats that entrap bubbles and are buoyed into the froth ( Bhambhani et al. The role of rheology (viscosity) in flotation is reviewed by Farrokhpay (2012), who notes effects in both the pulp and froth zones. Reducing the impact of slimes by controlled dispersion would be preferable.ĭispersants also lower pulp viscosity by reducing particle–particle interactions ( Jones and Horsley, 2000 Nagaraj and Ravishankar, 2007). To avoid slime-related problems, in some non-sulfide systems feeds are deslimed by classification (e.g., cycloning, see Chapter 9) with attendant loss of values. Coating of fine particles on larger particles (“slime coating”) is an example of aggregation. The action appears to be related to restoring high negative charge to generate electrostatic repulsion between particles, accomplished through a combination of adsorption of the silicate anion (SiO 3 2−) and removal of metal cations from the surface, sequestering them as insoluble metal silicates. A reagent used primarily as a dispersant is sodium silicate. Rendering the surface hydrophilic means water is held as a hydrated layer on the particle surface, which not only depresses the particle but also makes it less prone to aggregate (to aggregate the hydrated layer on the contacting particles has to be expelled).
Several of the depressants also function as dispersants ( Nagaraj and Ravishankar, 2007). Finch FRSC, FCIM, P.Eng., in Wills' Mineral Processing Technology (Eighth Edition), 2016 12.6.6 Dispersantsĭispersed particles represent a better condition for selective flotation than systems where the particles are aggregated.
0 kommentar(er)
