Successful blending occurs with respect to non-additive properties (likes combustion reactivity of coal, ash characteristics, grindability index
, and swelling characteristics) of two coals.
Grindability of coal is generally estimated by two indices: (a) work index in which energy consumption for obtaining product of constant fineness is measured; and (b) grindability index in which fineness of final product is measured for same grinding work of the standard samples.
ASTM, 2004 (D409-02) was followed for determining hardgrove grindability index of coal samples.
The aim of the present work was to investigate the microwave drying characteristics of oil shale and its influence on the physicochemical properties, including proximate composition, grindability index, pore structure and chemical change.
The grindability index of oil shale was determined using Hardgrove method.
The maximum possible grinding capacity depends on the coal character (grain composition, grindability index
, rock concentration, moisture content etc.), on the dust system characteristics (drying, ventilation and grindability) and on the amount of coal fed into the mill, on the coal feeding system and its regime (Formusatin, 2008).
To determine the rank of coal, laboratory tests such as proximate analysis (moisture, volatile matter, fixed carbon and ash), ultimate analysis (elemental composition of organic fraction on weight percent basis; carbon, hydrogen, oxygen, nitrogen and sulfur), heating value, hard groove grindability index
(HGI) and petrographic analysis were carried out.
The lab is now proceeding with a range of further tests including Ultimate Analysis, Trace Elements, Ash Analysis, Ash Fusibility, Hardgrove Grindability Index
and Petrographic analysis.