Pneumatic cells

Ekato Intermig agitator, 1 739, 740 Ekoflot pneumatic cell, 16 653 Elaidic acid, physical properties,... 

Goitorgens Goitnn [500-12-9] Golay pneumatic cell Gold... 

Fig. 6.19. Differential pressure cells (transmitters) (a) pneumatic cell (b) capacitive...

Froth flotation is an application of foams that is used to separate mineral components from each other based on their having different surface properties, typically their wettability and surface electrical charge. For example, froth flotation is the classic process used to separate copper from lead ore. The process involves having hydrophobic particles attach to gas bubbles which rise through a turbulent suspension to create a surface foam called a froth. Figure 10.2 shows an illustration of a mechanical flotation cell. This is the classic flotation device [53,91,625], First, the flotation feed particles are well dispersed into a particle suspension. Together with chemical flotation aids, such as collectors and frothers, this constitutes what is called the flotation pulp. In a mechanical flotation cell, air is fed in the form of fine bubbles and introduced near the impeller (see Figure 10.2). In addition to mechanical flotation cells, there are also pneumatic cells and cyclone flotation cells. Pneumatic... 

Condition the solids to alter the wettability of the mineral and the gangue. The fundamental surface wettability for sulfide ores is different from oxides, silicates, and salt-type minerals. pH is a critical variable. Typical conditioning chemical additions include collector about 0.01 to 0.1 kg/Mg solids frother about 0.01 to 0.5 kg/Mg solids activator about 1 to 4 kg/Mg solids depressant about 0.02 to 2 kg/Mg solids. Allow 6-min contact for conditioning. Bubble size about 1000 pm. Flotation rate constant is 0.2 to 1 min sink rate constant is 0.005 min-. Flotation cells mechanical cell for fast float, sequential separation, and relatively coarse particle diameter 1.6 to 2.4 kW/m cell volnme. Pneumatic cell for relatively dilute feed concentrations and smaller particle diameters. Air blower 0.5 kW/m cell volume. Typical solids throughput 0.4 to 0.8 kg/s m feed concentration 10 to 40% w/w. Air escape velocity 0.02 m/s. Float times 6 to 20 min. Feed concentration to rongher or scavenger 30% w/w to cleaner 10% w/w. 

There are two basic designs of floatation cells mechanical and pneumatic. Mechanical cells are the most common design and generally use a stator with an overhead-driven rotor to circulate the slurry medium (pulp) and also to provide air dispersion and bubble shear see Figure 4.11. Aeration may be self-induced or introduced from an external air source, and the froth is removed using peripheral launders. Pneumatic cells make use of aeration and hydrodynamics to circulate and suspend the pulp as well as achieving froth separation. 

Thermocouple (voltage) or bolometer (resistance) Ciolay pneumatic cell Pyroelectric cell icapacitance)... 

Pneumatic cells are very sensitive devices, useful from the near-infrared region to the 300-150 GHz microwave range (1 GHz = 1 Gigahertz = 10 Hertz). In a pneumatic cell, incident radiation heats a confined gas, which expands, moving a curved diaphragm with a mirror surface. A light beam reflected from this surface to a photocell varies in intensity with the movement of the diaphragm. 

Pneumatic cell for relatively dilute feed concentrations and smaller particle diameters. Air blower 0.5 kW/m cell volume. Typical solids throughput 0.4-0.8 kg/s m feed concentration 10-40% w/w air escape velocity 0.02 m/s. Float times 6-20 min. 

Pneumatic cell, less than mechanical cell. 

Detection of infra-red radiation is by means of its heating effect, and the thermo-couple, the bolometer and the Golay pneumatic cell are each used by different manufacturers. Photoconductive cells of the lead sulphide type, although having a speed of response superior to the heat-sensitive detectors, are not as yet sufficiently sensitive beyond about 7//. 

SPECIFIC THERMAL DETECTORS 3.3.1 Golay Cell (Pneumatic Cell)... 

Kenny et al. (1991) Novel infrared detector based on a tunneling displacement transducer by T. W. Kenny, W. J. Kaiser, S. B. Waltman, and J. K. Reynolds. Appl. Phys Lett. 59,1820-1822. Describes micromachined silicon pneumatic cell with an electronic displacement transducer. Performance of prototypes is competitive with the best mcooled infrared detectors. 

Hermes website. Accessed 9 May 2013 at http //hermes.material.uu.se/ klas/Thermal%20 microsensors%20and%20thermovision.pdf. This 24-page pdf does not include the name of the author or institution - It begins with 2. Thermal Radiation microsensors and thermovision. This is a clear overview of IR and detectors, and includes a quite detailed discussion ofGolay (pneumatic) cells, thermopiles, and microbolometers. The Golay Cell discussion includes formulas for membrane deflection. 

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