Carbones

UPCOMING SHOWS AN ANALYSIS OF COAL ORE

1 Magda Agudelo, Jonnathan Rincón

2 Alvaro Jimenez

1.2 District University of Bogotá

1Students, 2Faculty of Carbones

RESUMEN El presente trabajo se basa en la caracterización de una muestra de carbón de origen mineral. Mediante un análisis próximo se determinó los contenidos de humedad (h), materias volátiles (mv), cenizas (cz) y la respectiva densidad aparente de éste material, según las normas ASTM D3173 para la determinación de la humedad, norma ASTM D3302 para la humedad, la norma ASTM D271 para materias volátiles y la norma ASTM D3174 para la determinación de cenizas. La respectiva caracterización del carbón se realizó con una muestra de carbón en polvo con un tamaño de partícula menos a 0.2mm respectivamente. A partir de este análisis próximo se postula que la muestra de carbón se identifica como lignito, carbón de baja calidad.

ABSTRACT. This work is based on the characterization of a sample of coal mineral origin. By the near analysis moisture content (h) volatiles (mv), ash (cz) and the respective bulk density of this material it was determined according to ASTM D3173 standards for moisture determination, ASTM D3302 for moisture, ASTM D271 standard for the volatiles ASTM D3174 standard and to determine ash. The respective coal characterization was performed with a sample of coal dust with a particle size less than 0.2mm respectively. From this next analysis it is postulated that the coal sample is identified as lignite, low rank coal.

PALABRAS CLAVE: Humedad, cenizas, densidad, análisis próximo, normas ASTM,  tamaño de partícula, carbono fijo y carbón vegetal (madera).

KEYWORDS: Moisture, ash, density, proximate analysis, ASTM, particle size, fixed carbon and charcoal (wood).

INTRODUCTION

Coal is considered a solid fuel with more than 50% by weight carbon (70% by volume) resulting from the slow decomposition of large amounts of plant matter during geological times. Its main use is in the steel industry and power generation in thermal power plants.

Coal is constituted of carbon, hydrogen, oxygen, nitrogen and sulfur. The respective carbon, hydrogen, nitrogen and oxygen derived from the original plant; sulfur has an organic or inorganic origin from minerals that have doped carbon bed during their respective formation.

Theories about the formation of coal

Hickling. There is a continuity in training and the differences are based while lasted the carbonization process: Wood → peat → lignite → coal → anthracite.

Hilt. Carbonization is accentuated with depth due to the effects of pressure and temperature

Mackenzie-Taylor. Each type of coal is the end of a different process according to carbonization conditions.

[pic 1]

Figure 1. Scheme coal formation.

The next analysis according to ASTM D3172 coal is defined as the determination of moisture, ash, volatile matter, fixed carbon.

Residual moisture (ASTM D3173): It loses moisture to air dry coal when it is subjected to a temperature of 106 °C. The presence of a very high humidity retards the ignition of coal resulting in that there is not enough time for total consumption being evacuated part of it in the ashes.

Surface moisture: moisture is lost coal when it is air dried laboratory environment.

Total moisture (ASTM D3302M ISO 589): It is the sum of the surface moisture and residual moisture. It is necessary to know in buying and selling contracts, the evaluation and construction of industrial processes, coal handling and spraying.

Volatile materials (ASTM 3175, ISO 562): The volatiles are gaseous detachments of organic matter during heating required by the standard. As the coal is heated, gaseous and liquid products are released. The constituents are primarily water, hydrogen, carbon dioxide, carbon monoxide, hydrogen sulfide, methane, ammonia, benzene, toluene, naphthalene and tar vapor. As a general rule we can say that coals with high content of volatile combusted more easily and with long flame (there are some exceptions) and the percentage of volatile matter is low, generally higher preheating of coal is needed which is equivalent to a particular design boiler and also requires smaller pulverize coal.

Ash (ASTM D3174, ISO 1171): The ash from a coal is a product of combustion, ie a residue calcination at 750 °C (ASTM) or 815 °C (ISO) and mineral salts in existing coal. [2].

Dilute the fuel ash coal fraction; form deposits on the walls of the furnace and usually when they are in large quantities coal must be removed for these reasons should be known for: selecting equipment crushing, grinding, combustion and determine the washing and cleaning processes. Low ash content favor operating costs and the highest availability of equipment.

The behavior of the ashes depends on the composition. When are high in sodium (Na2O>2) promotes crusting and high in iron (Fe2O3) promotes the formation of slag.

Figure 2. General scheme next analysis of a sample of coal.

[pic 2]

MATERIALS

-        Coal sample

-        Porcelain crucible

-        Oven Lindberg

-        Analytical balance

-        Desiccator

-        Pycnometer

-        Watchglass

-        Spatula

-        Agitator

-        Water

METHODOLOGY

Initially a sample equivalent to 1,016 grams for examination moisture coal was taken, this was placed in a porcelain dish with lid and took the oven at 110 °C for one hour, to withdraw moisture have; after heating took a desiccator containing silica and that finally weighed with an analytical balance. Later the ash percentage of a sample of coal equivalent to 1,002 grams was determined, graduating muffle initially at 750 °C for 1 hour, at the end of the time weighed and the ash content is determined. For a sample of volatiles equivalent to 1,015 grams carbon for 7 minutes at a temperature of 950 °C, which was allowed to cool to room temperature and subsequently weighed was taken. The bulk density was determined with a pycnometer which previously weighed and thereto is added after the coal sample (1,035 grams) diluted in ethanol, the pycnometer was weighed and its respective density was determined. It denote that each of the processes developed with the respective ASTM standards to ensure better results.

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