Mindanao State University – Iligan Institute of Technology Department of Metallurgical Engineering
____________________________________________________________________________
ACTIVITY 2: Proximate Analysis of Coal
By
Nikie B. Alquizar Angelica B. Alvizo Christine Joy R. Baguio
A laboratory report submitted in partial fulfillment of the requirements for the Metallurgical Analysis Course (MET E 112) Section A56 (MTh 1:30-4:30PM)
Prof. Mercurio I. Espinido, Ph. D. Adviser
March 31, 2016
I. Abstract Proximate analysis helps in determining the valuable qualities of coal used in different industries. It is formally defined by a group of ASTM (American Society for Testing and Materials) methods and is an assay of the moisture, volatile matter, fixed carbon, and ash content of a coal sample. Moisture is determined by establishing the loss in weight of the sample when heated under rigidly controlled conditions of temperature, time and atmosphere, sample weight, and equipment specifications. Moreover, ash is determined by weighing the residue remaining after burning the coal under the same controlled conditions. Referring to the analysis of results, the coal sample used in the experiment passes the ASTM standards for moisture and ash determination having 14% and 12% respectively. For ASTM D3173-73, moisture ranges from 1.0 – 21.9% and for 250- μ m
(No. 60) samples in ASTM D3174-73/79 ash ranges from 2.68-17.86%.
Thus, it is concluded that the coal sample analyzed is feasible and efficient in terms of moisture and ash content.
II. Introduction Coal is classified into three major types namely anthracite, bituminous, and lignite. However there is no clear demarcation between them and coal is also further classified as semi- anthracite, semi-bituminous, and sub-bituminous. Anthracite is the oldest coal from geological perspective. It is a hard coal composed mainly of carbon with little volatile content and practically no moisture. Lignite is the youngest coal from geological perspective. It is a soft coal composed mainly of volatile matter and moisture content with low fixed carbon. Fixed carbon refers to carbon in its free state, not combined with other elements. Volatile matter refers to those combustible constituents of coal that vaporize when coal is heated. To be able to define the properties of coal, proximate analysis can be performed which is set of parameters that determine the fixed carbon, volatile
matter, moisture, and ash percentages of coal. In this activity, moisture and ash determination are performed.
III. Experimental Method Moisture Determination (ASTM D3173-73) For determining the moisture of coal, the oven shall be so constructed as to have a uniform temperature in all parts, have a minimum of air space, and capable of temperature regulation between the limits of 104 and 110°C. Preparation of the sample included constant weighing of the capsule (with cover) in the drying oven and cooled over the desiccant. Approximately 1 gram of coal sample (passing 250
μm
or No. 60 sieve) was placed in the capsule and weighed. By removing the cover, the capsule was quickly placed in the preheated oven
(at 104-110°C) through which passes a current of dry air. After an hour, the capsule was quickly covered and cooled in a desiccator over desiccant and weighed as soon as the capsule reached room temperature.
Ash Determination (ASTM D3174-73/79) The capsule containing the sample in moisture determination was used in in ash determination. After removing the covers, the capsule was placed in a cold muffle furnace and was heated gradually at such a rate that the temperature reaches 450-500°C in 1 hour. Heating was continued until a final temperature of 700-750°C was reached. The capsule was then cooled in a desiccator and weighed as soon as possible.
IV. Results and Discussions
Table 4.1 Tabular Data for Moisture Determination Initial Weight of
Weight of capsule
Remaining
Moisture
capsule
after heating, W2
coal sample,
content, %
(w/o cover) + 1 g of
(g)
(g)
coal, W1 (g) 34.50
34.36
0.14
Moisture content , =
14
W 1−W 2 34.50−34.36 ×100 = ×100 =14 initial g of coal 1
Fig. 4.1 ASTM D3173-11 Precision Table
As shown in Table 4.1, the remaining coal sample after heating is 0.14 g from 1 g. These data corresponds to a total of 14% moisture present in the sample lost during the process.
From the ASTM D3173-11 Precision Table, the standard coal
sample has a moisture content ranging from 1.0 – 21.9%. Thus, the coal sample used for moisture analysis in the set up passes the ASTM standards.
Table 4.2 Tabular Data for Ash Determination Weight of empty
Weight of capsule,
Initial weight
capsule and cover,
cover, and ash
of coal
Wa, (g) 33.50
residue, Wb, (g) 33.62
sample, (g) 1
Ash content, %
12
Ash content , =
W b −W a 33.62−33.50 ×100 = ×100 =12 initial g of coal 1
After heating the capsule in the furnace of 700-750°C, it weighed 33.62 g from 34.36 g heated from the oven. Ash content is determined by subtracting the weight of capsule and cover together with the ash residue after it was subjected to a higher temperature and the constant weight of the empty capsule and cover. The ash residue recovered in the process was about 12%
IV. Conclusions As stated in the discussion of moisture determination (ASTM D3173-73), the coal sample of 14% moisture passes the ASTM standards ranging from 1.0 – 21.9%. The ash content determined in the latter process is equivalent to 12%. According to ASTM D3174-73/79, the relative precision of 250- μ m
(No. 60) samples for ash
determination test method covers the range from 2.68-17.86%. Hence, the coal analyzed also passes the ASTM standards for ash content. Therefore, the coal sample used in the experiment is considered to be feasible in terms of its moisture and ash content.
V. References American Society for Testing and Materials (ASTM). Standard Test Method for Moisture in the Analysis Sample of Coal and Coke. 100 Barr Harbor Drive,
West
Conshohocken,
United
States.
https://www.scribd.com/doc/166533042/D3173-11-pdf#scribd (Accessed 2016-0325). American Society for Testing and Materials (ASTM). Standard Test Method for Ash in the Analysis Sample of Coal and Coke from Coal. 100 Barr
Harbor
Drive,
West
Conshohocken,
United
https://www.scribd.com/doc/170246036/D3174 (Accessed 2016-03-25).
States.
