why coal mine teperature is high than surface

Hot environment estimation of thermal comfort in deep

However, in Australian coal mines increasing strata temperatures at relatively shallow depths in combination with high surface ambient temperatures, eg, in Queensland, have led to uncomfortably high ventilation temperatures on longwall faces Wet bulb temperatures exceeding 30ºC and humidity of 95% to 100% on longwall faces were reached due to the added heat from broken coal and rock on

Why underground mines cost higher compared to surface

Why underground mines cost higher compared to surface coal mines Recall that it takes more time, pressure, and heat to form higherranked coal This means higherranked coal is largely buried

Coal | National Geographic Society

22122012· Surface Mining If coal is less than 61 meters (200 feet) underground, it can be extracted through surface mining In surface mining, workers simply remove any overlying sediment, vegetation, and rock, called overburden Economically, surface mining is a cheaper option for extracting coal than underground mining About two and a half times as much coal can be extracted per worker, per hour, than is possible with underground mining

The Temperature Of The Earth As Shown By Deep Mines

At the New Almaden quicksilver mine, in California, at a depth of about 600 feet the temperature was very high some 115 degrees; but in the deepest part of the same mine, 1,800 feet below the surface and 500 feet below sea level, the temperature is very pleasant, probably less than 80 degrees At the Eureka mines, in California, the air 1,200 feet below the surface appears nearly as cool as 100 feet below the surface The normal temperature

Generating clean energy from the coal mines | The Engineer

For mine water taken from close to the surface (typically 11 – 20˚C) heat pumps work at a coefficient of performance (COP) of 4 (ie for every 1kW of electricity you put in, you get 4kW equivalent back out in heat) And for higher temperature water taken from deeper mines, it becomes even more efficient “If you go to warmer temperatures of 30˚C plus then you get a coefficient of performance of 10,” he added

Surface mining Wikipedia

Overview

Why is the air temperature very hot in deep mines? | Yahoo

25082010· Near the surface, the average geothermal gradient is about 25 degrees centigrade (77 degrees Fahrenheit) for every kilometer of depth Some areas have much higher gradients because of deep fault zones, rifting, magmatic intrusions, or active tectonic forces The geothermal gradient can make conditions in the superdeep mines uncomfortable, dangerous and deadly Hot enough to spontaneously explode rocks or bend steel The TauTona Gold Mine in South Africa is the deepest mine

Why Surface Mine? | The Truth About Mountaintop Mining

Why do we surface mine a coal seam or group of seams instead of deep mining that reserve? The answer is generally determined by geology and topography However, in many cases the coal reserve has been previously deepmined and surface mining recovers what was left Surface mining through abandoned deep mines, recovering the blocks of coal that were left decades ago, is relatively

Pore characterization of different types of coal from coal

01032017· 1 Introduction Coal and gas outburst is one of the most serious disasters in underground coal mines , , , which can be attributed to several factors: high methane pressure, high methane content, high insitu stress, different coal properties, and complex geological conditions , , , Generally, the methane content in the coal seam mainly consists of the adsorbed gas and the free gas; the

Spoil tip Wikipedia

As some spoil tips resulting from industries such as coal or oil shale production, the waste can contain a relatively high proportion of hydrocarbons or even coal dust Spontaneous subterranean combustion may result, which can be followed by surface fires In some coal mining districts, such fires were considered normal and no attempt was made to extinguish them

Methane emissions from coal mines are higher than

The amount of methane released into the atmosphere as a result of coal mining is likely much higher than previously calculated, according to research presented at the annual meeting of the

Storage of Coal: Problems and Precautions

Oxidation of coal causes an increase in ignition temperature, If the coal is fragile, it will be fragmented so the percentage of small particle size material is increased, Oxidized coal decreases the performance of washing plants, As a result of storage of the coals containing high percentage of methane in

Coal World distribution of coal | Britannica

To be economically mineable, a coal bed must have a minimum thickness (about 06 metre; 2 feet) and be buried less than some maximum depth (roughly 2,000 metres; 6,600 feet) below Earth’s surface These values of thickness and depth are not fixed but change with coal quality, demand, the ease with which overlying rocks can be removed (in surface mining) or a shaft sunk to reach the coal seam (in underground mining), and so forth The development of new mining

Why is the air temperature very hot in deep mines? |

25082010· Near the surface, the average geothermal gradient is about 25 degrees centigrade (77 degrees Fahrenheit) for every kilometer of depth Some areas have much higher gradients because of

Coal mining Wikipedia

Coal mining is the process of extracting coal from the ground Coal is valued for its energy content and since the 1880s, 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 called a 'pit

COAL CHARACTERISTICS Purdue University

CARBON IN COAL Carbon forms more than 50% by weight & more than 70% by volume of coal (this includes inherent moisture) This is dependent on coal rank, with higher rank coals containing less hydrogen, oxygen & nitrogen, until 95% purity of carbon is achieved at Anthracite rank & above Graphite formed from coal is the endproduct of

The Actual Difference Between Surface and Underground

Surface mining is suitable for large, lowgrade ore deposits which occur below a thin layer of rock, or alluvial deposits found in sand and riverbeds Underground mining is used for small, highgrade deposits covered with a thick overburden (soil and rock above the ore), or for deep and sloping deposits General Process

Pore characterization of different types of coal from

01032017· The pore and surface features imply the sorption characteristics of coal; higher rank coal usually has higher adsorption capacity because of the larger number of micropores and greater surface area In micropores, the adsorption potential energy is enhanced because of the heterogeneous feature of the coal surface, interconnected pores and the pore geometry effect of the coal [35]

Why does petroleum burn faster than coal? Quora

For liquid fuels, they are generally atomized with steam or compressed air to small particles The smaller the particle, the higher is its ratio of surface area to mass These particles of fuel can only burn on the surface, where their molecules can react directly with oxygen So, the smaller the particles of atomization, the faster they

EGEE 101 exam 1 practice quizzes Flashcards | Quizlet

conductive There are a couple of "new" coalfired electricity electricity generation technologies that are much cleaner and more CO2 sequestration ready than current plants One is oxyfuel combustion, the other is [answer] gasification

Coal World distribution of coal | Britannica

To be economically mineable, a coal bed must have a minimum thickness (about 06 metre; 2 feet) and be buried less than some maximum depth (roughly 2,000 metres; 6,600 feet) below Earth’s surface These values of thickness and depth are not fixed but change with coal quality, demand, the ease with which overlying rocks can be removed (in surface mining) or a shaft sunk to reach the coal seam (in underground mining), and so forth The development of new mining

Storage of Coal: Problems and Precautions

Oxidation of coal causes an increase in ignition temperature, If the coal is fragile, it will be fragmented so the percentage of small particle size material is increased, Oxidized coal decreases the performance of washing plants, As a result of storage of the coals containing high percentage of methane in

Pressure and density of air in mines

the health and safety of the miners, as high temperatures are In the Western Deep mine, refrigerated air is pumped into the depths, where the miners work through an insulated shaft in order to bring the temperature 2 down to 28°C As a result, the pressure of air increases to twice 12 that at the surface

Mining Underground mining | Britannica

Counting against underground mining are the costs, which, for each ton of material mined, are much higher underground than on the surface There are a number of reasons for this, not the least of which is that the size of underground mining equipment—because of ground conditions, ore body geometry, and other factors—is much smaller than in the open pit Also, access is much more limited All of this

Spontaneous combustion of coal SlideShare

03112014· Air and water from the surface can gain access to the coal and increase the potential for sp combustion •Also at depths, the in situ coal temperature tends to be higher making deeper seams more vulnerable to sp combustion •At greater depth, the excessive rock pressure acting on coal pillars results in their crushing and thereby increases the surface area of coal exposed to oxidation, which

Moisture in Coal, Coal Analysis, Kentucky Geological

07102019· Moisture absorbs heat, so high moisture content in coal reduces the relative efficiency of heating when a coal is combusted This is why lowrank, highmoisture coals have lower calorific values (Btu/lb) than highrank, lowmoisture coals Moisture adds weight to coal, and also contributes to spontaneous combustion in lowrank coals, and as such, affects handling and transport Moisture can also cause coal

Pore characterization of different types of coal from

01032017· The pore and surface features imply the sorption characteristics of coal; higher rank coal usually has higher adsorption capacity because of the larger number of micropores and greater surface area In micropores, the adsorption potential energy is enhanced because of the heterogeneous feature of the coal surface, interconnected pores and the pore geometry effect of the coal [35]

The Actual Difference Between Surface and Underground

Surface mining is suitable for large, lowgrade ore deposits which occur below a thin layer of rock, or alluvial deposits found in sand and riverbeds Underground mining is used for small, highgrade deposits covered with a thick overburden (soil and rock above the ore), or for deep and sloping deposits General Process

Study finds methane emissions from coal mines ~50%

01022021· 01 February 2021 The amount of methane released into the atmosphere as a result of coal mining is likely approximately 50% higher than previously estimated, according to research presented at the recent annual meeting of the American Geophysical Union

Why does petroleum burn faster than coal? Quora

For liquid fuels, they are generally atomized with steam or compressed air to small particles The smaller the particle, the higher is its ratio of surface area to mass These particles of fuel can only burn on the surface, where their molecules can react directly with oxygen So, the smaller the particles of atomization, the faster they