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The general practice in coal preparation plants (CPP) for metallurgical coal in India has been desliming the plant feed at 0.5 mm and processing 13 x 0.5 mm in heavy media (HM) cyclones (HMC) and 0.5 mm x 0 in froth flotation. Coal preparation plants for thermal coal have mostly been partial-wash plants, bypassing 10 mm x 0 or 13 mm x 0 to the prod...
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Full-wash thermal coal preparation plant (CPP) circuits in which typical +1 mm raw coal is processed in heavy media vessel (HMV) and/or cyclone (HMC), and 1 mm × 0.15 mm raw coal is processed in an intermediate water-only gravity separation circuit, such as spirals, water-only-cyclone/spirals combination, teeter-bed separators, or Reflux® classifie...
Citations
... ash (as received basis) with >6100 kcal/kg (as received basis) gross calorific value and with a maximum total moisture of 11.0%-12.0% (Saurabh et al., 2017). Therefore, mined coal is processed in single or multiple stages in the CPP to achieve the desired quality before its supply to the end-user industries. ...
Noise as an environmental hazard remains a perennial issue in mineral industry which increases with mechanization. It is estimated that 12.4% –25.7% mining and processing workforce are suffering from noise-induced hearing loss in India. Both area noise survey and personal noise dosimetry conducted to assess magnitude of problem in coal and mineral processing plants. Area noise levels in more than 50% of the samples exceeded 90 dB(A). The noise levels within control cabins (70.2–81.5 dB) fell below stipulated warning limit of 85 dB(A). Out of 27, 19 personal noise samples exceeded the stipulated 8 h exposure limit while they crossed danger limit value of 90 dB in six samples. Noise levels reported in the present study are not much different from those in the studies of the 1970s and 1980s. Overall severity of exposure might have decreased over the years but still rendering the plants unhealthy.
Vide Notification G.S.R. 02(E), dated January 02, 2014, Ministry of Environment & Forests has amended Rules in respect of use of washed/ blended or beneficiated coal with ash content not exceeding 34 percent on quarterly average basis in Thermal Power Plants. Such notification brings demand for more and more coal preparation plants to meet the requirement. Most of the coal washeries will now be the pit head. Some need to be built on brown field mining and rest from green field mining blocks. Before commencing design of a coal preparation plant or washery, it is essential to have detailed information of the raw coal to be treated together with a clear understanding of the products required. Prediction of raw coal size distribution, particularly the amount of fine material (below 0.5 mm), is difficult and the methods employed should be large scale pilot plant studies or techniques to simulate coal degradation and shale breakdown in water.
Generating the detailed information of raw coal for a brown field mining is comparatively easy as most of the faces are exposed and easy to extract samples from there. However, the same is very difficult for a Green field mining block. In Green field mining block, sampling can be either through the prediction method from slim core or through Large Diameter cores.
In this paper, an attempt has been made to understand the impact of improper or incomplete coal testing on the plant economics, product quality and yield. Further, the effect and need of proper sampling strategy and the efficient sampling approach at different phases of the project is covered. Also, the details about tests that need to be conducted before designing or setting up a Coal Preparation Plant is explained in this paper.
