Prospecting and exploration of coal
Производство и промышленные технологии
The search for economically useful mineral deposits is called prospecting. Mining activities include prospecting and exploration for a mineral deposit through finding - proving - developing - extracting - and processing the ore. Before mining - prospecting and exploration required to locate characterize and prove a potential...
prospecting and exploration.
Before coal can be extracted from the Earth, it must first be found. The search for economically useful mineral deposits is called prospecting. Mining activities include prospecting and exploration for a mineral deposit through finding - proving - developing - extracting - and processing the ore.
The mining activities can be divided into three major phases:
1. Before mining - prospecting and exploration required to locate, characterize and prove a potential ore body
2. Mining - coal or ore extraction: underground or surface mining
3. After mining - processing and preparing the raw ore for the end product.
The aim of geological prospecting is to provide information on a preliminary estimation of the deposit and the costs of the geological investigations to be made. It also indicates whether it is available to continue the exploration or not.
Prospecting work includes three stages:
finding signs of the mineral - finding the deposit - exploring the deposit.
Last century prospectors looked for visible evidence of mineralization on the surface of the Earth. To recognize valuable minerals it was necessary to know their various distinctive physical properties. For example, gold occurs in nature as a heavy yellow metal. Galena, the most important mineral containing lead, is dark grey, heavy and lustrous. Certain deposits are found only in a particular type of ground. Coal seams are found in sedimentary formations mainly consisting of sandstones and shales.
Studying and exploring deep deposits, it is of great importance to establish sequences controlling their localization. Geophysical methods make it possible to determine the thickness of deposits, and under favourable conditions to establish the composition of the ore as well, thereby decreasing the number of exploratory openings to a minimum.
Once a discovery is made, the property is explored to determine the most important characteristics of the deposit: its size, shape, orientation in space, and location with respect to the surface, as well as mineral quality and quantity distribution, and the quantities of these different qualities.
Although in searching for valuable minerals direct observation is still widely practiced, the modern prospector employs a combination of geologic, geophysical, and geometrical tools to provide indirect indications for reducing the search radius. When making the geological maps, the geologists study all the data of ground aerial geological surveys.
The object of modern techniques is anomalies - differences between what is observed and what would normally be expected. Aerial and satellite images help to identify mineralizations that may be indicated by differences in geologic structure or in rock, soil, and vegetation type.
In geophysical prospecting, gravity, magnetic, electrical, radio-metric methods will distinguish such rock properties as density, electrical conductivity, radioactive decay, etc.
In geochemical prospecting the search for anomalies is based on the measurement of trace elements or chemically influenced properties. Samples of soil, sediments, water, rocks, vegetation and humus, animal tissues, gases and air are collected and tested so that unusual concentrations can be identified. Based on these studies a number of prospects are identified. The most promising of these becomes the focus of a field exploration programme.
Several exploration techniques are used, depending on the type of deposit and its proximity to the surface. Trenching, for example, provides, accurate near-surface data. Sometimes special drifts are driven in order to explore a deposit. The most widely used exploration technique is the drilling of probe holes. In this practice, a drill with a diamond-tipped bit cuts a narrow kerf of rock, extracting a cylindrical core of rock in the Centre.
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