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 is the standard grindability of coal?
The standard method of coal grindability is called
Hardgrove (ASTM D409)
, though this method does not provide reproducible and repeatable results for hard coal.
What is swelling index and grind ability index of a coal?
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. Grindability is an important factor for the design a coal mill.
How is grindability calculated?
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 is HGI petcoke?
5.1 The HGI is
used to predict the ranking of raw petroleum cokes or calcined petroleum cokes
in industrial size mills used for crushing operations. The rankings are based on energy required and feed rate or both.
What is swelling index of 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 obtained by heating prepared samples of coal over a burner and comparing the resultant coke button to a series of standard profiles.
What is weathered coal?
The slow disintegration of coal into fires in surface stockpiles under the action of the weather
, particularly frost after a wet period. See Also: spontaneous combustion.
What is caking index of coal?
The Caking Index,
G
, has been widely popularized and applied in coal geological exploration, production and utilization departments in China. ... The value of G characterizes the content of active component of coal, and is considered as a measure of the degree of reduction of coal.
How coal is Analysed?
Proximate analysis: determines moisture, volatile matter, ash yield, and fixed carbon content in coal. ... Ultimate analysis: determines amounts of the major elements in coal: carbon, hydrogen, nitrogen, sulfur, oxygen. Vitrinite reflectance (Ro): determines the relative rank of coal.
How is the quality of coal determined?
The rank of a coal is determined primarily by
the depth of burial and temperature to which the coal was subjected over time
. With increasing temperature, peat is converted to lignite, a very soft, low-rank coal.
What is grindability test?
A grindability test is
a procedure that evaluates the resistance of a material to ball milling
. This test is an effective way to calculate and compare the Bond Work Index (BW¡) of different ores. The higher the Bond Work Index, the more difficult it is to grind the material.
What is HGI?
|
Acronym Definition
|
HGI Hartford Geriatrics Initiative
|
What is limestone Bond Index?
Abstract—The Bond work index is a research methodology, which is widely used for the estimation of power required to grind the materials. ... In this regard calculation of work index of limestone made by standard Bond grindability test. Ball mill was employed to conduct the grinding test of seven different samples.
What is volatile matter coal?
Volatile matter is defined as the
gases driven off when coal
is heated to 950°C (1742°F) in the absence of air under specified conditions and is consisted of short and long chain aliphatic carbon atoms (linked in open chains) or aromatic hydrocarbons (one or more six-carbon rings characteristic of benzene series) and ...
What is the difference between coking coal and non coking coal?
Noncoking coals have higher ash content and are typically used in thermal power plants as steam coals. Coking coal is the type of coal which on heating in the absence of air undergoes a transformation into a plastic state, swells, and then solidifies to
form coke
.
What is swelling index of soil?
The swell index which is
the slope of the rebound curve of void ratio versus the logarithm of the effective pressure curve
is used to estimate the consolidation settlement of over-consolidated fine grained soils.
