1601 Size (mm) 6-3 3-0.5 - 0.5 Mass % 7.3 6.9 8.5 Sp. Gr. Float Float Float Wt% Ash% Wt% Ash% Wt% Ash% < 1.40 7.3 8.1 19.1 7.9 19.7 6.1 1.40 – 1.50 18.3 18.6 18.1 17.8 13.6 13.9 1.50 – 1.60 19.9 26.4 12.6 26.2 12.6 19.8 1.60 – 1.70 16.9 34.5 13.4 34.1 12.7 28.8 1.70 – 1.80 10.8 43.0 9.9 41.2 10.2 46.8 1.80 – 1.90 7.4 48.9 6.4 49.2 6.7 53.9 > 1.90 19.4 68.9 20.5 73.7 24.5 68.8 Total 100.0 36.7 100.0 34.9 100.0 34.4 The washery is being set up under Build-Operate-Maintain (BOM) basis under which BCCL is the Owner of washery; finance the complete set up cost and provide land for washery. The BOM Operator shall be responsible for selection of the state of the art technology, designing, construction, successful commissioning of the project and subsequent operation and maintenance of the washery for 10 years. M/s Aryan Coal Beneficiation is the BOM Operator for this washery. The washery is under construction and brief description of process provided by M/s ACB is mentioned below & is also presented in Figure 3 : 1. Crushing of as received raw coal to pass 20 mm & desliming of 20 coal at 2 mm 2. Washing of 20-2 mm fraction in Primary HM Cyclone for generation of clean coal (i.e. HM cyclone, o/f) & sink (i.e. HM Cyclone, u/f) 3. Rewashing of u/f of Primary HM Cyclone in Secondary HM Cyclone to produce middlings (i.e., o/f of Secondary HM cyclone) & rejects (i.e. u/f of Secondary HM Cyclone) 4. Classifying of (-) 2 mm fraction through Classifying Cyclones at (-) 0.5 mm to produce two size fractions i.e. 2-0.5 mm and (-) 0.5mm 5. Beneficiation of 2-0.5 mm size fraction in Spirals to produce fine clean coal as overflow and middlings as underflow 6. Beneficiation of (-) 0.5 mm size fraction in Mechanical froth flotation cell to generate concentrates (i.e. clean coal) and tailings (i.e. rejects). An attempt has been made to design a process flowsheet for washery grade, W-V (ash-38%) coal through washability data of North-South Tisra mine (50 – 0 mm) by using LIMN: Flowsheet processor for optimum recovery of clean coal. LIMN is a spreadsheet add-on that contains information on each component of a coal preparation plant (CPP). LIMN model can easily be customised to match the configuration of an active or simulation of CPP. By creating a simple flowsheet within the LIMN model, the progress of a coal feed through different circuits can be visually shown. Once the flowsheet is set-up, the efficiencies of each component can be adjusted to reflect actual performance under plant conditions. After establishing the efficiencies for each component of CPP, the LIMN model can simulate beneficiated products. Once each CPP component is added in sequential order, the LIMN model simulates how a coal feed will beneficiate through the set design. LIMN model uses the principal of incremental quality, which is defined as - clean coal yield for parallel operations is highest when all circuits are operated at the same incremental ash. This concept, which has been long recognised in coal preparation. There is ash controllers in the LIMN model to control the RD within design ranges to achieve a specified ash percentage per product stream. LIMN model uses process design criteria (PDC) assumptions as input parameters. LIMN models are robust as component(s) can be added or removed from the flowsheet to test design configurations or possible modifications [8]. The data that feeds into a LIMN model is the washability data (i.e. float & sink data) of raw coal for different size range to be fed to the CPP. The LIMN model can generate the washability data of the size fractions as per the flowsheet, even if the actual washability available is for different size fractions [8].
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