15. Proximate analysis of coal

15. PROXIMATE ANALYSIS OF COAL

Expt. No.

Date:

AIM

To determine moisture, volatile and ash contents in a given coal sample by proximate analysis.

PRINCIPLE

Proximate analysis is a type of analysis of coal. It informs about the practical utilization of coal. It is the determination of moisture, volatile matter, ash and fixed carbon. Calorific values mainly depends on the presence of moisture, volatile matter and ash contents. So it is essential to measure these items.

PROCEDURE

1. Moisture content

The given coal sample is air dired. First empty silica crucible is exactly weighed in an analytical balance, let its weight be X₁ gms.

Now 1 gm of air dried coal sample is taken in the silica crucible and let its weight be X₂ gms. The crucible is kept inside the electric oven, maintained at 110°C, for one hour. After heating, the crucible is removed and kept in a desiccator for cooling and weighed. Let the weight of the crucible after cooling be X₃ gms.

The difference in weight is reported in percentage as the amount of moisture in coal.

2. Volatile content

The coal sample, after the determination of moisture content, is heated in a furnace at 925°C for 7 minutes. After heating, the crucible is removed from the furnace and cooled in a desiccator. After cooling, it is weighed. Let the weight of crucible be X₄ gms.

Loss in weight is reported as volatile matter on percentage basis.

3. % Ash content

Weight of empty crucible = X₁ = ….. gms

Weight of crucible + sample = X₂ = ………. gms

4. Fixed carbon

% F.C = 100 – (% moisture + % volatile matter + % Ash)

= 100 – (......... + ......... + .........)

= ............... %

3. Ash content

The residual coal, after the analysis of moisture and volatile contents, is heated in a muffle furnace maintained of 725 – 750°C for 1/2 hour. Heating is done without crucible lid. The crucible is cooled first in air and then in desiccator. The crucible is then weighed, let the weight of the crucible be X₅ gms.

4. Fixed carbon content

The sum total of percentages of moisture, volatile matter and ash, subtracted from 100, gives the percentage of fixed carbon.

RESULT

The coal sample contains

1. Moisture = …….. %

2. Volatile content = ………. %

3. Ash content = ………. %

4. Fixed carbon content = ………. %

WEIGHING AND PREPARATION OF SOME IMPORTANT REAGENTS

TABLE OF EQUIVALENT WEIGHTS