Coal is a vital component in steel production as a source of carbon. The QDI
CoalPro™ Vitrinite Reflectance Measurement System, from CRAIC
Technologies, is designed to ensure that the coal blends used in steel production
are optimum and consistent from batch to batch.
CRAIC Technologies QDI CoalPro Designed to Ensure Coal Blends Used in Steel Production are optimum and consistent
Coke is used as a reducing agent when smelting iron ore in the first stage
of making steel. Coke is made by the pyrolysis of blends of low-sulfur and low-ash
coal. The process is called “coking” and it is done to drive off
the volatile components of coal leaving a gray, 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. Too much or too little results in poor quality
coke. Generally, levels of 26 to 29 percent of volatile materials are considered
optimum. Thus 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 that the coking process is
consistent and that the volatiles are maintained at an optimum level. This requires
testing of the coal so that it meets the specific criteria to make good quality
coke and to maintain a high level of coke production. One of the more 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 standardized 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 546 nm. The procedure is 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 done 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 therefore its value for coking. As
hundreds of measurements need to be done on each sample, this used to be a very
time consuming process. Today, instruments such as the QDI CoalPro™ can
automate this process and dramatically improve a laboratories throughput and
accuracy. The results is a histogram from which the thermal maturity of the
coal to be used in steel production can be determined.
For more information about the QDI CoalPro™ Vitrinite Reflectance Measurement
System and petroleum source rock analysis, please visit www.microspectra.com.