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. 2022 Jan 19;7(4):3348-3358.
doi: 10.1021/acsomega.1c05346. eCollection 2022 Feb 1.

Upgrading of Low-Grade Colombian Coals via Low-Cost and Sustainable Calcium Nitrate Dense Media Separation

Orla Sioned Aine Williams  1 , Patrick Daley  1 , Joseph Perkins  2 , Karen Lorena Martinez-Mendoza  3 , Juan Guerrero-Perrez  3 , Lyna Maria Sabogal Mazabuel  3 , Edward Andres Garcia Saavedra  3 , Maria Trujillo  3 , Juan Barraza-Burgos  3 , Maribel Barajas  4 , Manuel Hernando Romero  4 , Edward Henry Lester  1
Affiliations

Upgrading of Low-Grade Colombian Coals via Low-Cost and Sustainable Calcium Nitrate Dense Media Separation

Orla Sioned Aine Williams et al. ACS Omega. .

Abstract

Wet coal beneficiation in Colombia is prohibitive due to the high cost and scarcity of commonly used dense media. The practical value of this study is that it demonstrates for the first time that a common fertilizer, calcium nitrate, can be used in the beneficiation of low-grade Colombian coals. Three high-ash low-grade Colombian coals (Valle, Cundinamarca, and Antioquia) commonly used in Colombian sugar mill stoker furnaces were tested. Coal mineralogy and prevalence were analyzed before and after washing using mineral liberation analysis. The swelling potential of the coals was assessed using a novel application of thermal mechanical analysis (TMA) and an ash fusion oven (AFO). Calcium nitrate reduced ash levels across all size fractions, even for high-ash coals like Valle (29% to below 7%) to acceptable levels for coke manufacturing or pulverized fuel combustion. The novel use of TMA and AFO to analyze coal swelling demonstrated that swelling varies under constrained and unconstrained conditions and the small sample size allows for rapid testing of coal swelling. This study has demonstrated that the use of common fertilizers can allow beneficiation to become a processing option for low-grade coals in Official Development Assistance countries where conventional dense media is prohibitively expensive.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Particle size range vs cumulative passing for the coals used in the washing tests.
Figure 2
Figure 2
Ash content by particle size for Antioquia and Antioquia Beneficiated (A), Valle and Valle Beneficiated (B), and Mayagüez and Mayagüez Beneficiated (C). NB. AB = Antioquia, VB = Valle Beneficiated, AB = Antioquia Beneficiated, Myz = Mayagüez, and MB = Mayagüez Beneficiated.
Figure 3
Figure 3
Mineral liberation analysis (MLA) of as-received Valle <6 mm (A), removed residue (B), and remaining coal (C).
Figure 4
Figure 4
Mineral liberation analysis (MLA) of as-received Antioquia <6 mm (A), removed residue (B), and remaining coal (C).
Figure 5
Figure 5
Mineral liberation analysis (MLA) of Mayagüez remaining coal (A) and removed residue (B).
Figure 6
Figure 6
Proximate analysis of as-received Antioquia and Valle coal, and Antioquia, Mayagüez, and Valle washed residue and float section.
Figure 7
Figure 7
Swelling of Antioquia (A), Cundinamarca (B), and Valle (C) in an ash fusion oven (AFO) up to 1000 °C and via thermal mechanical analysis (TMA) in air up to 800 °C.
Figure 8
Figure 8
Swelling of Valle (A) and Antioquia (B) as-received, washed float, and washed residue coals, and Mayagüez washed float and residue coal (C) in a TMA.
See this image and copyright information in PMC

References

    1. Ministerio de minas y energia. Cadena Del Carbón; 2012.
    1. Oei P. Y.; Mendelevitch R. Prospects for Steam Coal Exporters in the Era of Climate Policies: A Case Study of Colombia. Clim. Policy 2019, 19, 73–91. 10.1080/14693062.2018.1449094. - DOI
    1. López I. C.; Ward C. R. Composition and Mode of Occurrence of Mineral Matter in Some Colombian Coals. Int. J. Coal Geol. 2008, 73, 3–18. 10.1016/j.coal.2007.03.005. - DOI
    1. Rivera-Cadavid L.; Manyoma-Velásquez P. C.; Manotas-Duque D. F. Supply Chain Optimization for Energy Cogeneration Using Sugarcane Crop Residues (SCR). Sustainability 2019, 11, 6565.10.3390/su11236565. - DOI
    1. Meshram P.; Purohit B. K.; Sinha M. K.; Sahu S. K.; Pandey B. D. Demineralization of Low Grade Coal - A Review. Renewable Sustainable Energy Rev. 2015, 41, 745–761. 10.1016/j.rser.2014.08.072. - DOI