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Determination of Volatile Matter Content of Coal
Coal is one of the most important sources of energy in many countries and its utilization has both environmental and health implications. The calorific values, composition, size and shape of coal particles, caking power and combustibility, as well as other performance characteristics of the coal that are used for commercial purposes, depend upon its Volatile Matter (VM) content. Determination of VM content is an important factor in evaluating the quality of coal particles for their commercial use.
Volatile matter (VM) is the portion of coal that is liberated as gaseous products (mainly carbon dioxide, carbon monoxide and hydrocarbon gases) when the coal is heated in an environment with limited oxygen supply.The volatile matter content, usually expressed in weight percent, is an important parameter in estimating the energy value of coal and also influences its physical and chemical properties. Therefore, accurate determination of Volatile Matter (VM) Content of coal is crucial to evaluating the quality of coal before it is used commercially.
The determination of the Volatile Matter (VM) content of coal is usually done by the method known as “Thermogravimetric (TG) Determinator Method”. In this method, an accurately weighed a sample of coal is heated in a thermogravimetric analyzer in a temperature range of up to 900°C and the weight loss is measured. The weight loss is generally divided into several distinct stages, including constant rate, decelerating rate and accelerating rate of weight loss. Each weight loss is recorded and the final weight loss is the volatile matter content of the coal sample.
The instrument required for determination of Volatile Matter (VM) content of coal is the Thermogravimetric (TG) Determinator. This device is a sensitive, digital balance with a high-precision integrated heating platform. The instrument uses a micro-processor-controlled weighing system and an accurate digital thermometer to perform accurate measurements. The instrument is equipped with a thermoelectric heater and a thermal tester which are used to control the heating of the sample.
The initial step for the determination of Volatile Matter (VM) Content of coal is to accurately weigh a sample of the coal. The weighed sample is then heated in the thermogravimetric analyzer at a specified temperature for a specified time period,depending on the sample size. The weight loss during the heating process is recorded in the thermogravimetric analyser and the volatile matter content is calculated by subtracting the initial weight of the sample from the final weight.
The determination of Volatile Matter (VM) Content of coal is an important analysis and can be used to evaluate the quality of coal particles before they are used commercially. The method of determination of Volatile Matter (VM) Content of coal described here is the Thermogravimetric (TG) Determinator Method which requires the use of a thermogravimetric analyzer. This method provides accurate analyses and is relatively easy to perform, but it is time consuming and expensive.
Other methods for determination of Volatile Matter (VM) Content of coal exist, such as Loss on Ignition (LOI), Proximate Analysis, and Ultimate Analysis. However, these methods do not provide the accurate results offered by the Thermogravimetric (TG) Determinator Method. In addition, these methods require the use of complex laboratory equipment and involve time consuming and expensive laboratory procedures.
In conclusion, the determination of Volatile Matter (VM) Content of coal is an important factor in evaluating the quality of coal before it is used commercially. The method of determination of Volatile Matter (VM) Content of coal usually employed in laboratories is the Thermogravimetric (TG) Determinator Method which requires the use of a thermogravimetric analyzer. This method provides highly accurate results and is relatively easy to perform but is time consuming and expensive. Other methods exist but they do not provide the high accuracy or convenience offered by the thermogravimetric method and require expensive laboratory equipment and time consuming procedures.
