Which coal has highest grindability index?
The Hardgrove grindability index (HGI) is the most expedient. There is a close relation between HGI and the coal quality, as well as the power consumed in grinding. Accordingly, the HGI values of coal samples may be used to optimize the crushing of coal as a preliminary to coke production.
What does a low Hardgrove grindability index indicate?
Hardgrove Grindability Index (short HGI) is a measure for the grindability of coal. Grindability is an index, therefore it has no unit. The smaller the HGI, the harder is coal texture and less grindable is the coal.
How do you calculate HGI of coal?
The HGI grindability value is calculated from the following formula: HGI = 13+6,93(50-m) The m value is the weight of oversize expressed in grams. The Hardgrove grindability index value is influenced by petrographic composition of coal.
What does grindability mean?
: capacity for or resistance to being ground prepared an index of the grindability of various southern coals.
What is swelling index and grind ability index of a coal?
The free swelling index (FSI) is used to measure a coal’s swelling properties when heated under prescribed conditions without physical restrictions. The FSI is useful in determining the plastic properties of coal, and as an indication of the coal’s suitability for use as a coking coal.
Which is the ideal swelling index for coke manufacturing?
Swelling index varying between 2. -5 ideal for coke manufacturing.
How is %of C and H determined in coal?
Ultimate analysis of a sample of coal was found to contain percentage by weight of following elements: C=86.80. H=4.25. Calculate the weight of theoretical air for complete combustion of 1 kg of fuel and the weight of products of combustion per kg of fuel burnt.
How C and H is Analysed in ultimate analysis?
Ultimate analysis provides a convenient method for reporting the major organic elemental composition of coal. For this analysis, a coal sample is combusted in an ultimate analyzer, which measures the weight percent of carbon, hydrogen, nitrogen, sulfur, and ash from a coal sample.
What is the difference between free ash and fixed ash?
Widely used to designate the part of the ash content of a coal that is structurally part of the coal itself and cannot be separated from it by any mechanical means, usually amounts to about 1%. Also called dirt; fixed ash; constitutional ash. Opposite of free ash.
What is the difference between ADB and ARB in coal?
ARB puts all variables into consideration and uses the total weight as the basis of measurement. ADB (air-dried) basis neglect the presence of moistures other than inherent moisture unlike ARB which uses total moisture.
What is TM in coal?
Two stage total moisture determination is used when the coal sample is too small mass or too wet to divide or crush without the potential of losing significant amounts of moisture. TMar, % = [Rm,ad, % x (100 – Fm,ad, %) / 100] + Fm,ad % TM = Total moisture; Fm = Free Moisture; Rm = Residual moisture.
What is GCV and NCV of coal?
Gross calorific value (GCV) assumes all vapour produced during the combustion process is fully condensed. Net calorific value (NCV) assumes the water leaves with the combustion products without fully being condensed. Fuels should be compared based on the net calorific value.
What is the ash content of coal?
The ash content of coal is the non-combustible residue left after carbon, oxygen, sulfur and water has been driven off during combustion. The remaining residue or ash is expressed as a percent of the original coal sample weight.