Coal mining in the past was not as environmentally friendly, or regulated.
There were a number of different coal mining methods used in the past.
Coal mining in the past was not as safe as the current mining methods used.
Coal mining in the past started in the middle of the seventeen hundreds, in the state of Pennsylvania. Over the years, many ways to remove this substance from the earth have been used, with methods being classified as underground or surface. The reason that it was first mined from the earth was not for electricity, but to be used in steel mills. It was not until the eighteenth century that coal was used to generate electricity to light homes and businesses. The first miners used a method called room and pillar, and eventually this method was combined with a method termed retreat. Coal mining in the past depended on workers and supporting the mine walls and ceilings. Rooms were carved out of the mine, and these were supported by massive pillars and beams. Miners would remove the coal from these underground rooms. When retreat mining was done along with room and pillar, the rooms were collapsed as the miners retreated from the mine. This collapse opened up even more coal seams, which could then be recovered. It was not until the middle of the nineteen sixties that this process changed much. This is when longwall mining started being used.
Coal mining in the past includes the longwall mining method as well. This
method is much more effective, because a much larger percentage of the seam can
be removed. This method uses a machine which carefully collapses a huge part of
the room in a controlled manner, allowing a lot more of the seam to be accessed
and removed. Surface mining can also be done if the seam is close to the
surface. In this method the ground covering the coal seam is removed, then the
coal is removed. The ground is put back down and seeded, to return the land back
to the original condition. Unlike coal mining in the past, current mining
operations do consider their environmental impact on the earth and surrounding
areas, but this still does not negate the harmful effects that these operations
can have. Coal is a fossil fuel which is not renewable, and it takes millions of
years for this fuel to be created. Once it is gone it can not be replaced, and
there are limited reserves left in the earth. Coal is mainly used to generate
electricity in the United States, and when it is burned it releases large
amounts of greenhouse gases and pollution. This causes damage to the environment
and speeds up the global warming as well. As the professional manufacturer of
complete sets of mining machinery, such as sand washer, Henan Hongxing is
always doing the best in products and service. dryer
Coal mining in the past did not factor in any environmental damage. Because of this many of the areas where this type of mining originated, like the state of Pennsylvania, are full of polluted and contaminated waters and lands. Chemicals and heavy metals caused streams and lakes to become toxic to fish and local wildlife, and even humans suffered from many effects caused by this pollution. Coal is no longer used to heat homes, but it is still used to generate large amounts of electricity in coal burning power plants. This causes high amounts of carbon and other greenhouse gases to be released into the air, and to damage the ozone layer. There is also substantial particle pollution released when coal is burned, and this pollution can cause asthma and other medical conditions in people who breath in these irritants. Safety is also another factor which has improved over time, and today miners and mining operations are done in a much safer manner. The processes have changed since the beginning of coal mining, but the damage done to the environment is still substantial and should be stopped.
来自 “ ITPUB博客 ” ，链接：http://blog.itpub.net/26834288/viewspace-730975/，如需转载，请注明出处，否则将追究法律责任。