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Yes, there is a relation between Hardgrove Grindability Index (HGI) and the grade of coal. Essentially, the HGI is a measure of the grindability of a coal, indicating how easily it can be pulverized. Lower-grade coals typically have lower HGIs, meaning they are harder to grind compared to higher-grade coals.
What is the HGI(Hard Grove Index)?from britannicameasurement of coal grindability...in a laboratory mill of standard design. The percent by weight of the coal that passes through a 200-mesh sieve (a screen with openings of 74 micrometres, or 0.003 inch) is used to calculate the Hardgrove grindability index (HGI). The index is used as a guideline for sizing the grinding equipment in a coal-preparation plant.Can you tell us the HGI for Indian coal?
Coal sample of specific size is put into griding vessel. HGI machine is rotated for 60 times (or so) and the coal is taken out. Agian, coal is checked for the sieve passing ratio and its HGI is calculated against standard curve.
The Hardgrove Grindability Index was developed in the 1930s from experimental work by R. Hardgrove to determine the relative difficulty of reducing various coals to a particle size required for efficient combustion in pulverized coal boiler furnaces. The HGI is now commonly applied to specifications for coal to be used in the iron making, cement and chemical processes. There are several different "standard" methods for the determination of HGI (e.g. - AS1038 Part 20:2002, and ASTM D409-2006), which can lead to significantly different results. Further, HGI is an empirical measure and not a physical proprty of coal; as such the results of any standard test have relatively low repeatability for a given coal sample. In general, the higher the HGI value, the more readily a coal can be reduced to smaller particle sizes.
hgi
hgi
HgI is the chemical formula for mercury iodide, a compound composed of mercury and iodine. It is a yellow solid that is used in various applications such as in the laboratory as a reagent and in the production of organic compounds.
Coal
Coal
HgI is not a chemical reaction, it is the empirical formula for the compound Mercury (I) iodide, Hg2I2
2KI + HgCl₂ -----> 2KCl + HgI₂
There are sustantial amounts of the following Natural Resources located in the Indian subcontinent iron Ore, coal, gem stones, and fertile soil.