1603 medium density, pressure stability, efficient magnetite recovery circuit, etc it is not widely used unless very low ash product is required and NGM is very high. Due to more auxiliary equipment required for its operation, its capex & opex is generally high. A very high quality and super fine grind magnetite power is required and loss of magnetite is also more during its operation. Due to this challenges, Fine DMC is not commercially installed anywhere in India. Recently, Tata Steel in its Jharia CPP, Jamadoba Plant has successfully done a trail run of Fine DMC (0.5 – 0.25 mm) to recover clean coal ash of 14% @ 69% yield from 26% feed ash. Globally, it was used upto 1980’s, with the development of Spirals, use of fine DMC is becoming restricted. But again after 2005, reconsideration of fine DMC has started to produce fine coal at a higher product quality with maximum recovery, which no other equipment can deliver. As there is need of hour to obtain maximum recovery of the available resources, so fine DMC is gaining popularity. A lot of research work is going on to optimise its performance and reduce the operating cost. Another advanced beneficiation technology for intermediate size is Teeter Bed Separator (TBS). It is a gravity separator developed from the conventional Hydrosizer technology and operates based on principles of hindered settling and fluidization to accomplish separation of particles. An upward water supply flow fluidizes a top-fed bed of fine particles that is forming an autogenous medium that is suitable for separation of the particles according to their size and densities. This process takes advantage of the inherent settling velocity differences between various sizes and densities of particles exhibited. Heavy particles settle more quickly in a multi-particle system formed as a result of the suspension of water and middle-mass particles in the separator. As a result, heavy particles are separated from light particles by settling rapidly through suspension. Lighter particles, on the other hand, float through suspension due to their lower settling rates. However, some small size, high density particles and larger size, low density particles report to overflow and underflow. Thus, there is misplacement of particles and separation efficiency (Ep: 0.12-0.18) is reduced due to his effect, especially when NGM is high, particle size range is broad. Thus, a low ash coal with good yield cannot be obtained in this FBS. They can handle limited feed size and typically 4:1 is used as the largest ratio of coarsest to smallest particles. These challenges in this FBS is overcome with the development of Reflux Classifier. Figure 5- Teetered Bed Separator Schematic
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