Mining is a necessary component of the world we live in and it has been practiced for thousands of years. The mining industry produces billions of tons of raw product every year. The process of mining is very complicated and involves plenty of physics! Two main components of the mine cycle are: Drilling, and Blasting. Some important factors in mining are the pillars, rock elasticity, and the slope stability of the ground being mined.
A basic method for destroying rock is mechanically induced stress, such as drills and erosion jets. A turbine drill for example, uses a turbine to rotate a diamond faced cutter wheel. The power output, p, can be calculated using the equation p=2 πNT where N is the rotational speed of the turbine and T is the torque on the cutter wheel. As the rotary speed increases, the torque decreases. The maximum power output of a turbine drill is when the rotary speed is between 5,000 and 10,000 rev/min.
Erosion jets can be classified as low speed or high speed. The low speed jets use abrasive particles, such as sand to erode rock at 10 to 200 m/s and the high speed jets use water at 200 to 1,000 m/s. The high speed jets are used for the hardest rock and require pressures up to 5,000 kg/cm²!
In underground, non coal mining, the excavation of rock is done largely by conventional percussive drills. These break the rock by indentation. The drilling machine applies a force to the drill bit, giving it a velocity which hits the rock and causes it to break. The equation for the peak stress induced by the drill bit on the rock is as follows: σ = ρ cv, where σ is the maximum stress induced, and ρ, c, and v are the density, compressional wave length, and velocity of the drill bit, respectively.
In coal mining, ...
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... Now there is an added force from the water called pore pressure and the normal force is decreased making the slope more likely to fail. The following diagram represents this scenario with 'W' as the gravitational force downward of the upper rock, 'p' as the pore pressure from the water, and 'A' as the area that the water affects.
Mines are erected by pillars, which have factors of safety. The factor of safety is the average strength divided by the average stress ratio. When this ration falls below 1.00, there is pillar instability. If one pillar in a mine collapses, the result is greater force acting on the rest which in turn increases their stress and decreases their factors of safety. If all of the pillars are highly stressed, one pillar failure could lead to a domino effect and the collapse of a mine. 1.60 is considered a good factor of safety for pillars.
This rock type could prove dangerous, being soft and with little solidness in its structure. Therefore placing the protection over the rock cliffs was a very well thought and planned engineering
First, the miners blast the taconite. Taconite needs to be blasted by small explosives since it’s such a hard rock (MDNR,). These blasts would be happening at least once a week. Usuall...
Concretions form in many different ways. The box shape of some ironstone concretions most often depend on the way a sandstone or shale bed breaks up due to the action of weathering into regular blocks of various sizes. The way in which this separation takes place along natural planes of weakness in a rock such as a horizontal bedding surface and vertical joints. Before this process of separation, as well as during the separation ground water soaks into the rock and circulates through the planes of weakness making the rock more porous.
One of the biggest natural resources used in fracking is water. On average, around one to eight million gallons of water are used on a fracture job. There are also around 500,000 active fracture sites around the world and each site can be fractured around 18 times. This means that roughly 72 trill...
Objectives • To evaluate the difficulty of mining and reclamation To calculate costs, expenses, income, and profit from a hands-on mining exercise. • To evaluate the effectiveness of reclamation and its added costs to mining. To describe the increasing rarity of some non-renewable mineral resources. Introduction Minerals play an important role in our day-to-day life, but we often do not contemplate how the minerals are obtained. Minerals are scattered all over the world, just like any other resource.
Borehole mining (BHM) is a process that incorporates a high pressure waterjet cutting system and a down-hole slurry pumping system through a single borehole drilled from the surface into the mineralized rock. The waterjet cuts the material resulting the slurry flows into an eductor pump near the base of the tool and pumped out to the surface. A cavity will be created as a consequence of this excavation process [2]. Understanding the relationship between the cavity stability and the operational parameters is critical in designing any borehole mining system.
No Author Presented. "Deep Sea Mining." Deep Sea Mining. N.p., n.d. Web. 28 Mar. 2014. .
The accidents involving machinery kill and/or hurt more coal miners in a year than any other mining accident. The machinery in mines are located in cramped spaces with little light, causing miners to have two times the chance of accidents. The accidents involving roof and rib failures can usually be averted if a mining company has a roof support plan. For a roof support plan to be made, information like entry widths, mine geometry, the number of pillars that must be left up right, and the number of bolts that must be used are needed (Cobb 3 of 5) Accumulations of gases in underground coal mines is another very serious hazard. If certain gases like methane and carbon monoxide are at or above 5% in the air they can cause violent explosions. Blasting in coal mines are the main cause for such dangerous levels of carbon monoxide.
Though it has had many negative impacts on the environment in the past, mining is a vital industry completely necessary to our economy and lives. Nearly every item we use or encounter in our day to day lives is mined or contains mined products. Without the excavation of such materials things like computers, televisions, large building structures, electricity, and cars would not be possible. Virtually every technological and medical advance uses minded materials, without which millions would suffer. Some examples of minerals in the home include the telephone which is made from as many as 42 different minerals, including aluminum, beryllium, coal, copper, gold, iron, silver, and talc. A television requires over 35 different minerals, and more than 30 minerals are needed to make a single personal computer. Without boron, copper, gold and quartz, your digital alarm clock would not work. Every American uses an average 47,000 pounds of newly mined materials each year, which is higher than all other countries with the exception of Japan, which is a staggering figure representative of our dependence and need for mined minerals. Coal makes up more than half of nation’s electricity, and will continue to be the largest electrical supplier into 2020 & accounting for some 95 percent of the nation's fossil energy reserves – nine of every ten short-tons of coal mined in the United States is used for electricity generation. As the population of the world grows more mineral resources must be exploited through mining in order to support the rising demand for such products. Though it may present a hazard to the environment and those physically located nears the mines, the materials extracted from mines...
Hydraulic Action, when waves hit the cliff, air is forced into cracks, and then as the wave retreats this air expands explosively. Over time the cracks enlarge, weakening the base of the cliff causing erosion.
Lucas, Chris, and Kate Seigfried. "The Rock Cycle Web Site - Cementation and Compaction." The Rock Cycle. N.p., 4 Dec. 2000. Web. 02 Dec. 2013. .
The main objective of crushing theory is to express the relationship between the energy consumed and the amount of the size reduction which resulted through this energy consumption. According to Lee (2009) there are three classical crushing theories in all which assumes rocks, (ore is also classified under rocks) to be brittle. Rittinger was the first to suggest the theory in which he proposed in 1867, he suggested that the surface area produced by crushing is directly proportional to the energy consumed. Rittinger formulated an equation in which energy consumed is in the form of Rittinger. Below is the Energy Rittinger equation
In our days, mining for resources is inevitable. The resources we need are valuable in everyday life. Such resources mined up are coal, copper, gold, silver, and sand. However, mining poses environmental risks that can degrade the quality of soil and water, which can end up effecting us humans if not taken care of and many of the damages are irreversible once they have occurred.
Due to the fact that rocks are composed of high intensity of elastic and brittle material, they therefore store considerable amount of strain energy that results from elasticity, during the action of plate tectonic. The brittleness leads to development of concurrent cracks on the rocks as a result of plate’s action.