Gravity Flotation

In general, conventional oil water separator in which gravity is the major reason for this separation method, can he basically designed using Stokes Law. 

The negative velocity is referred to as the oil droplet rise velocity. The water density and viscosity are shown in Table 6. As those values mainly depend on temperature, the appropriate temperature should be applied to obtain the suitable water density and viscosity for gravity flotation design. 

The droplet size of the oil particle should be determined experimentally to apply in Eq. (1). For example, a diameter of petroleum oil globule is typically 0.015 cm (21). The equation reduces to 

To obtain the horizontal flow velocity, the rate of flotation is applied as follows  

However, the horizontal flow velocity should not be exceeded 0.0152 m/s. Thus, if the calculated number is larger than this value, the 0.0152 m/s should be apphed. 

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Combination of gravity-flotation tin beneficiation method (lodge deposits)... 

Figure 21.2 Combination of gravity-flotation beneficiation flowsheet (simplified), Wheal Jane...

Plain gravity flotation Example API Oil-water separator... 

FIGURE S.3. Simplified flow sheet of a combined gravity-flotation procedure as applied at Canada Tungsten Mining Corporation (before closing down) [S.l]. 

Flotation. Flotation is a gravity separation process which exploits differences in the surface properties of particles. Gas bubbles are generated in a liquid and become attached to solid particles or immiscible liquid droplets, causing the particles or droplets to rise to the surface. This is used to separate mixtures of solid-solid particles and liquid-liquid mixtures of finely divided immiscible droplets. It is an important technique in mineral processing, where it is used to separate different types of ore. 

Gravity concentration, ie, the separation of ore from gangue based on the differences in specific gravities, using jigs, heavy—medium separators, or spiral concentrators for example, is appHcable for lead ores. However, the predominant beneficiation technique used in modem plants is the bubble or froth flotation (qv) process (4,5). 

Although the size separation/classification methods are adequate in some cases to produce a final saleable mineral product, in a vast majority of cases these produce Httle separation of valuable minerals from gangue. Minerals can be separated from one another based on both physical and chemical properties (Fig. 8). Physical properties utilized in concentration include specific gravity, magnetic susceptibility, electrical conductivity, color, surface reflectance, and radioactivity level. Among the chemical properties, those of particle surfaces have been exploited in physico-chemical concentration methods such as flotation and flocculation. The main objective of concentration is to separate the valuable minerals into a small, concentrated mass which can be treated further to produce final mineral products. In some cases, these methods also produce a saleable product, especially in the case of industrial minerals. 

Further upgrading of the potassium chloride content of the chloride salts recovered from the initial heavy-medium separation takes place in a second heavy-medium separation at a somewhat lower specific gravity than the first separation. Sodium chloride is discarded as a waste the enriched KCl fraction is sent to a flotation process where a final separation of KCl from NaCl is made. Mine-mn ore less than 1 mm that is not amenable to... 

Costs Because sink-float processing is applied to relatively coarse particles and is a single-pass operation, capital and operating costs are usually considerably lower than would be required for a flotation or a gravity mill of the same capacity. A large flow of water is required for feed preparation and for media recovery, but almost total recoveiy for recirculation is possible. A minimum of two job-trained operators per shift is generally required by law, but these would be able to attend several separators at almost any feed rate. 

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