Craic Technologies has introduced a vitrinite reflectance measurement system that is designed to ensure that coal blends used in steel production are consistent from batch to batch.
The 308 Coal system automates the time-consuming measurement process to improve laboratory throughput and accuracy.
Coke is used as a reducing agent when smelting iron ore in the first stage of making steel.
It is made by the pyrolysis of blends of low-sulphur and low-ash coal.
The coking process is carried out to drive off the volatile components of coal, leaving a grey, porous solid.
Blends of bituminous coals are commonly used as the coal must have a certain amount of volatile matter in order to make good-quality coke.
Generally, 26-29 per cent of volatile materials are considered optimum.
Therefore, the coals and coal blends must be tested prior to being used to make coke and steel.
Different grades of coals are mixed together so the coking process is consistent and so the volatiles are maintained at an optimum level.
This requires the coal to be tested to ensure that it meets the specific criteria to make good-quality coke and to maintain a high level of coke production.
One of the most important tests is vitrinite reflectance.
Vitrinite is a maceral and is comprised of various polymers, cellulose and lignin.
Measuring the amount of light reflected by vitrinite macerals is a key test to determine the thermal maturity of the coal blend and its suitability for steel production.
The procedure has been standardised by a number of international bodies including both ISO and ASTM.
All of the standards require the use of a microphotometer - a device designed to measure the intensity of light reflected from a microscopic sampling area at 546nm.
The procedure is said to be simple; the microphotometer measures the amount of light reflected from samples from the coal blend at hundreds of points, after which a statistical analysis is carried out by the computer.
The results of the statistical analysis are used to determine the amount of vitrinite in the coal blend, its thermal maturity and its value for coking.
As hundreds of measurements need to be done on each sample, this can be a very time-consuming process.
Now, thanks to the 308 Coal and a programmable microscope, this process can be automated.
The results can be presented in all of the standard forms, ranging from tables to histograms, from which the thermal maturity of the coal can be determined.
