1.0 Introduction
Coal is an amorphous substance derived by the carbonization of vegetation of prehistoric ages, containing free carbon and different hydrocarbons and also complex substance carrying oxygen’s, sulphur and nitrogen, contaminated with various amounts of mineral matter, such as pyrites, gypsum, lime, magnesia, silica, soda and potash found in beds or viens in the earth and used as fuel. It is brittle, compact, massive and sometimes laminated, and varies in colour from black to brown.
Coal has also been defined in many ways but perhaps the most explicit definition is that “coal is a combustible organic rock having its origins in the accumulation and partial decomposition of vegetation.
Coal is widely distributed, and reserves of it are sufficient to last hundreds or thousands of years. It has long been the backbone of industrial life.
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitation of the study and Definition of technical terms.
1.1 Background of Study
Countries that have embraced it have prospered politically and commercially, while those that have not have embraced it have retreated into handicraft or agricultural nationalism. In England, coal became widely used in households during the 19th century, after it was first discovered in antiquity.
By the thirteenth century trade in it was active. The invention of the stream engine stimulated active coal mining, and then the industrial age commenced in England, when coal replaced manpower, and eventually mechanical power held away. When iron are was smelted by charcoal and the forests of England were ranishing, it was discovered that anthracite was a smelting fuel. This was another stimulus to coal mining. Later, when coke was made from bituminous coal, it was found to be a still superior fuel, the coal industry receive a great impetus, and huge industrial expansion ensured.
A further stimulus to the coal industry occurred when cities began to produce artificial was from coal for domestic and industrial use. It’s high position, which receded under the competition of oil and gas, is again coal which is of plant origin, composed highly of carbon with carbonaceous fuels that differ in the relative amounts of moisture, volatile matter and fixed carbon deposits were formed from the remains of vast forest of trees, shrubs and plant which flourished in the hot and humid climate of 250 to 400 million years ago. These flora died and rotted and were buried and consolidated under sediments deposited by encroaching seas. The coal seams so formed lay undisturbed until the coming of man.
The Chinese are said to have used coal three thousand years ago, but there is no evidence that other ancient civilization used it. The Venetian explorer, Marcopolo, records in the account of his thirteenth century travels through cathana that the natives burned a black stone dugout of the mountains.
Furthermore, coal is a combustible organic rock composed principally of consolidated and chemically altered vegetal remains which undergo geologic process, working over vast spains of time, compressed and altered decaying plant material that resulted in an increase of the percentage of carbon with increasing heat and pressure, different ranks of coal can occurs lignite (the softest), sub bituminous, bituminous, and anthracite (the hardest). Upon close examination some coals having bright, shiny bands of varying thickness which alternate with duller bands, where as other coals show no banding. The horizontal layering is characteristic of all sedimentary rocks and reflects the initial accumulation of the organic rich materials. Bright layers (vitrinite) consist primarily of woody cell wall materials, while the dull layers (exinite) consist primarily of the most resistant plant remains, such as spores and cuticles of leaves and rootlets these organic portions of coal are as the various types of coalfields plant material. Banded coal are referred to as attrite or splint coal types, where as the non-banded are cannel and or boghead coal types. Each has its own characteristics and appearance that reflect the environment conditions responsible for its formation.
Enugu coal is sub bituminous type of coal according to the classification of the American Society of Testing Material (ASTM) this was formed during the cretaceous period, about 120 million years ago. It is characterized by high moisture and volatile matter contents, nitrogen and hydrogen, but low in sulphur content. It has a poor coking property and a fairly high ash content, but with a fairly high fussion temperature that prevents clinkering.
The coal has fairly high calorific value and is good for steam raising as fuel in solid or pulverized form. However, this does not stand up well on exposure to the atmosphere as it dulls in appearance and develops some fine cracks after some months, but it does not decrepitated badly.
The calorific value of the coal (the most important property of the fuel) can drop by 15% of the original value under four months in storage, depending on particle size; lower if in layer lump and considerably higher if in smaller particles. A number of experiments has been carried out to determine these changes in Enugu coal.
