Hardmetals. Determination of insoluble (free) carbon content. Gravimetric method

Abstract A simple, accurate method for the determination of free carbon in either raw or vulcanized rubber is presented. It has replaced the nitric acid method entirely in the laboratory of the United States Rubber Company, Detroit, Michigan. A study of the effects of interfering substances, and numerous comparisons of results by the cresol and the nitric acid methods, are given. Results by the cresol method, in the absence of interfering substances, are within 1 per cent of the calculated free carbon content. The method requires only simple apparatus readily available.

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Gravimetric and instrumental methods comparison for experimental determination of carbonate carbon content in solid mineral fuels

Thermal Science ◽

10.2298/tsci210522237m ◽

2021 ◽

pp. 237-237

Author(s):

Marija Mirkovic-Gorgievski ◽

Ana Marinkovic ◽

Nikola Zivkovic ◽

Emila Zivkovic

Keyword(s):

Carbon Content ◽

Gravimetric Method ◽

Total Carbon ◽

Thermal Engineering ◽

Instrumental Method ◽

Total Carbon Content ◽

Thermogravimetric Analyzer ◽

Carbonate Carbon ◽

Heat Value

The content of combustible elements in solid mineral fuels (carbon, hydrogen, etc.) are very important, since they most directly affect the heat value. It should be noted that the fuel heat value depends on many other constituents, such as ash and moisture. In this paper, special attention has been paid to carbon content. In solid mineral fuels, carbon is found alone or bound in the form of various compounds. One of them is mineral carbonate compounds bound as carbonate carbon, which originates from absorbed carbon dioxide from atmosphere. Determination of carbonate carbon content of solid mineral fuels was performed by standard gravimetric method (according to ISO 925: 2019), and newly developed instrumental method, using thermogravimetric analyzer LECO TGA 701. Comparison of obtained experimental results was done. Four types of coal, Kolubara lignite, Kostolac lignite, brown coal and control coal sample were included in experimental analysis. In addition, moisture in the samples was also determined using analytical method and inspected using LECO TGA 701 thermogravimetric analyzer, as well as total carbon content using the LECO CHN 628 elemental analyzer. An analysis and comparison of the obtained results was performed, and comments and conclusions are presented. The experiments were done in the department for fuel characterization, Laboratory for Thermal Engineering and Energy, Institute of Nuclear Sciences Vinca.

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