File Name: modern american coal mining methods and applications .zip
It's been 30 years since the classic Mining Technology: Theory and Practice was published, and much has changed in the coal mining industry during that time.
The various methods of mining a coal seam can be classified under two headings, surface mining and underground mining. Surface and underground coal mining are broad activities that incorporate numerous variations in equipment and methods, and the choice of which method to use in extracting a coal seam depends on many technological, economic, and social factors. The technological factors include, at a minimum, the number of seams, the thickness and steepness of each seam, the nature and thickness of the strata overlying the seams, the quality of the coal seams, the surface topography , the surface features, and the transportation networks available. Economic factors include energy demand and its growth, the supply and cost of alternative sources of energy, coal quality and the cost of coal preparation, the selling price of coal, advancements in technology that affect costs of production, and environmental legislation.
Coal mining is the process of extracting coal from the ground. Coal is valued for its energy content and since the s, has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United Kingdom and South Africa , a coal mine and its structures are a colliery , a coal mine is a 'pit', and the above-ground structures are a ' pit head '. In Australia , "colliery" generally refers to an underground coal mine.
Coal bursts involve the sudden, violent ejection of coal or rock into the mine workings. They are a particular hazard because they typically occur without warning. This paper puts the US experience in the context of worldwide research into coal bursts. It focuses on two major longwall mining coalfields which have struggled with bursts for decades. In Colorado, the longwalls of the North Fork Valley NFV also work at great depth, but their roof and floor strengths are moderate, and most bursts have occurred during entry development or in headgates, bleeders, or other outby locations. The NFV bursts also are more likely to be associated with geologic structures and large magnitude seismic events. The paper provides a detailed case history to illustrate the experience in each of these coalfields.
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. A lthough the United States has the vast coal resource described in the previous chapter, perhaps as much as 4 trillion tons, the key issue for policy makers is the amount of coal that is economically recoverable. This is not a fixed quantity, but depends on the geological resource, the market price, and the cost of mining. The particular characteristics of the coal mining industry create unique challenges as it endeavors to provide coal to the market at a competitive price, continually improve miner safety and health, and meet environmental and community requirements. This chapter provides a brief description of the characteristics of the coal industry in the United States, presents an overview of coal extraction and processing methods, and discusses the major issues associated with coal mining and processing. A summary of current research activities supported by state and federal agencies provides the context for recommendations for essential future research.
Mining explained. Open-pit, underwater, and underground mining. These are the three main methods of mining we use to extract our products from the ground. In this Digging Deeper article, we take a look at these different methods and provide a glimpse into what each involves. Mining is at the heart of our business at Anglo American. It is the foundation against which all of our activities rely and gravitate around.
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. An underground mine consists of the portals entrance and exits to the mines , mains, submains, panels, and working faces. The panels are the working sections of the production operation. Depending on the mining method, a working section can have one or more working faces. The mining activities that traditionally take place to advance a working face further into the coal seam, called unit operations, include cutting, drilling, blasting, loading, and hauling the coal from the current position of the face to the planned advance distance position of the face. Supporting the newly exposed roof and extending the ventilation arrangement and other utilities to the new working face are also considered unit operations.
Gold Mining Methods Some modern commercial placer operations are quite large and utilize heavy equipment and river diversions. Gold mining in Alaska. By , surface mining was conducted with steam shovels designed for coal mining. Methods of extraction The
Room and pillar variant of breast stoping , is a mining system in which the mined material is extracted across a horizontal plane, creating horizontal arrays of rooms and pillars. To do this, "rooms" of ore are dug out while "pillars" of untouched material are left to support the roof overburden. Calculating the size, shape, and position of pillars is a complicated procedure, and is an area of active research.
Он тихонько толкнул дверь, и та отворилась. Беккер с трудом сдержал крик ужаса. Меган сидела на унитазе с закатившимися вверх глазами. В центре лба зияло пулевое отверстие, из которого сочилась кровь, заливая лицо. - О Боже! - воскликнул он в ужасе. - Esta muerta, - прокаркал за его спиной голос, который трудно было назвать человеческим. - Она мертва.
Еще несколько секунд - и все решит один-единственный выстрел. Даже если Беккер успеет спуститься вниз, ему все равно некуда бежать: Халохот выстрелит ему в спину, когда он будет пересекать Апельсиновый сад. Халохот переместился ближе к центру, чтобы двигаться быстрее, чувствуя, что уже настигает жертву: всякий раз, пробегая мимо очередного проема, он видел ее тень. Вниз.
Это смертельная ловушка. Если даже он выберется на улицу, у него нет оружия. Как он заставит Сьюзан пройти вместе с ним к автомобильной стоянке. Как он поведет машину, если они все же доберутся до .
Мы говорим о математике, а не об истории. Соши замолчала. - Полезный груз? - предложил Бринкерхофф. - Количество жертв. Ущерб в долларах.
Ее основная работа в последние три года заключалась в тонкой настройке самого секретного компьютера в мире: большая часть программ, обеспечивавших феноменальное быстродействие ТРАНСТЕКСТА, была ее творением. Шифр в миллион бит едва ли можно было назвать реалистичным сценарием. - Ладно, - процедил Стратмор. - Итак, даже в самых экстремальных условиях самый длинный шифр продержался в ТРАНСТЕКСТЕ около трех часов. - Да.
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