Underground mining line

When any ore body lies a considerable distance below the surface, the amount of waste that has to be removed in order to uncover the ore through surface mining becomes prohibitive, and underground techniques must be considered. 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 means that productivity, as measured in tons produced per worker per shift, can be 5 to 50 times lower, depending on the mining technique, than on the surface. Balanced against this is the fact that underground only ore is mined, whereas in the open pit there are often several tons of waste stripped for each ton of ore. Once a decision has been made to go underground, the specific mining method selected depends on the size, shape, and orientation of the ore body, the grade of mineralization, the strength of the rock materials, and the depths involved.

For example, if the ore is very high grade or carries a high price, then a higher cost method can be used. In order to minimize the mixing of ore and waste, highly selective extraction methods are available, but if ore and waste can be separated easily later for example, by using magnets in the case of magnetitethen a less-selective bulk mining method may be chosen. The orientation, specifically the dipof the ore body is particularly important in method selection.

For ore bodies having dips in between these, special designs are required. The openings made in the process of extracting ore are called stopes or rooms. There are two steps involved in stoping. The first is development—that is, preparing the ore blocks for mining—and the second is production, or stoping, itself.

Ore development is generally much more expensive on a per-ton basis than stoping, so that every effort is made to maximize the amount of stoping for a given amount of development. For steeply dipping ore bodies, such as the one illustrated in the figurethis means having as large a distance as possible between production levels. The resulting larger openings would offer an opportunity to use larger, more productive equipment, and fewer machines and workplaces would be needed to achieve a given production level.

In stoping, the geometry—that is, the size and shape—of the ore body imposes one constraint on the size of openings that can be constructed, and the strength of the ore and wall rocks imposes another. Most rock materials are inherently much stronger than the concrete used in the construction of highways, bridges, and buildings, but they also contain structural defects of various types, and it is these defects that determine the strength of the rock structure.

Welcome to the brilliant world of underground mining

If the defects are very close together, filled with crushed materials, and unfavourably oriented, then the underground openings must be kept small. As one goes deeper into the Earththe thickness and, consequently, weight of the overlying rock increase. Pressure from the sides also increases with depth; the amount of this pressure depends on the rock type and the geologic situation, but it can range from about one-third of the vertical pressure to as high as three times the vertical.

These rock bursts are major limitations to mining at depth. A specialized field of engineering known as rock mechanics deals with the interaction between rock mass and mine openings. Prior to the production of ore, a certain capital investment in mine development work is required. In open-pit mines this consists of building access roads and stripping the overlying waste material in order to expose the ore and establish the initial bench geometries.

For an underground mine the development stage is considerably more complicated. Some of the development components of an underground mine are illustrated in the figure. The principal means of access to an underground ore body is a vertical opening called a shaft. The shaft is excavated, or sunk, from the surface downward to a depth somewhat below the deepest planned mining horizon.

At regular intervals along the shaft, horizontal openings called drifts are driven toward the ore body. Each of these major working horizons is called a level. The shaft is equipped with elevators called cages by which workers, machines, and material enter the mine. Ore is transported to the surface in special conveyances called skips.This site uses cookies to create a better experience for you.

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Or, if you already know the name of the dealer you're searching for, you can type in the dealer's name for a list of locations. If you search for vocational trucks elsewhere you will not get any results. Our underground mining team relies on close collaboration with our customers to develop equipment and support solutions that are customized for your application.

And we have an eye on the future, with new products, new ways of mining, and new ways to get more out of game-changers like technology and automation. One thing all Cat longwall systems have common is that they are all different — customized to meet our customers' specific needs, from low to high seam heights, for the longest longwalls and highest production demands.

Adapted to the mining challenges you face today, systems for longwall mining include hydraulic roof supports, high-horsepower shearers, automated plow systems and face conveyors — controlled and supported by intelligent automation. No two underground mining operations are the same. Internet Explorer users may experience issues with certain features of our site. Please try a current version of an alternate browser i. Cookie Policy. Hide remove. Open add.

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No Thanks I Accept.Inpeople everywhere were riveted to the story of the 33 miners in Chile trapped 2, feet meters underground in a copper and gold mine. The miners spent more than two months there, getting food, air and letters from loved ones through bore hills drilled to their location in a protected workroom. Meanwhile, the larger-scale drilling of an escape shaft made slow progress. Finally, on Day 69, rescuers lifted each of the miners out alive [source: Boston ].

The saga reminded the non-mining world of a usually invisible truth. Deep beneath the surface of the Earth lie some of the most frightening factories in the world: underground mines. Underground mines are the alternative to surface mines. Surface mines excavate from the top down, a method that can become inefficient at depths greater than about feet 60 meters [sources: Illinois Coal AssociationDe Beers ]. Undergrounds coal mines can drive 2, feet meters into the Earth and other types even deeper -- uranium mines can reach 6, feet, or 2 kilometers.

Mining has changed a lot from the images we have of the 19th century when men with shovels toted canaries to make sure the air underground was not toxic.

Modern mines feature extensive ventilation and water-drainage systems, high-tech communication networks and increasingly computerized machines that reduce the number of humans required underground.

All underground mines have some crucial components in common: ventilation shafts to clear toxic fumes from drilling and blasting; escape routes; access shafts to lower workers and equipment; ore-transport tunnels; recovery shafts to carry excavated ore to the surface; and communication systems to send information back and forth between the surface and the depths [source: Hamrin ].

No two mines are alike, though. Technology applications and basic decisions about design and mining method rest on considerations like the type of ore being mined, composition of surrounding rock, shape and orientation of the ore deposit, geologic features underground, and simple economics [source: United Mine Workers of America ].

There are hard-rock underground mines, and there are soft-rock underground mines. Coal deposits, for instance, live in relatively soft sedimentary rock.

Gold deposits live in igneous or metamorphic rock, which is relatively hard, as do diamondscopper, silver, nickel and zinc [source: Great Mining ]. Even within the hard-rock category, design and extraction methods vary, but almost all revolve around a few basic techniques:.

Room and Pillar — For relatively flat ore deposits, with little change in elevation throughout, miners drill an access ramp to the deposit and remove ore in a pattern of holes rooms and roof supports pillars. The rooms can be mined out using conventional charge-and-blast techniques or, more commonly now, with a machine called a continuous miner.

The continuous miner drills into the rock until it forms an excavated room, perhaps 20 to 30 feet 6 to 9 metersleaving in place a rock pillar to support the "roof" [source: United Mine Workers of America ]. The machine moves through the ore, creating rooms and pillars, until the full deposit is covered.

A final pass drills through the pillars to recover the ore there, allowing the roofs to collapse behind the machine as it leaves each room. Cut and Fill — For relatively narrow ore deposits, miners drill an access ramp adjacent to the ore deposit, from the surface down to the lowest point of the deposit.

An operator then drives a drill through the ore, creating a driftor a horizontal cut, from one side of the deposit to the other. In the hardest rock, no roof-support is needed; in softer rock, bolts may be placed in the roof as the drill progresses [source: Mining Know-How ].

Once the drift is complete, backfillor waste material, is spread into the open drift, creating a platform for the next pass. The drill drives on top of this backfill to cut another drift through the ore. This continues until the drill cuts a drift across the top of the ore deposit. This method can be used in wider deposits, as well, by drilling two adjacent access ramps and cutting two adjacent drifts, often called drift and fill [sources: Mining Know-How ].

Cut and fill is for hard rock, as it doesn't feature the support mechanisms inherent in and central to a method like room and pillar. The room-and-pillar approach, on the other hand, crosses easily into the softer stuff — and most coal mines.Underground hard rock mining refers to various underground mining techniques used to excavate hard mineralsusually those containing metals [1] such as ore containing goldsilverironcopperzincnickeltin and leadbut also involves using the same techniques for excavating ores of gems such as diamonds or rubies.

Soft rock mining refers to excavation of softer minerals such as saltcoalor oil sands. Accessing underground ore can be achieved via a decline rampinclined vertical shaft or adit. Declines are often started from the side of the high wall of an open cut mine when the ore body is of a payable grade sufficient to support an underground mining operation, but the strip ratio has become too great to support open cast extraction methods.

They are also often built and maintained as an emergency safety access from the underground workings and a means of moving large equipment to the workings. Levels are excavated horizontally off the decline or shaft to access the ore body. Stopes are then excavated perpendicular or near perpendicular to the level into the ore.

Development mining is composed of excavation almost entirely in non-valuable waste rock in order to gain access to the orebody. To start the mining, the first step is to make the path to go down.

underground mining line

The path is defined as 'Decline' as describe above. Before the start of Decline all preplanning of Power facility, drilling arrangement, dewatering, ventilation and, muck withdrawal facilities are required. Production mining is further broken down into two methods, long hole and short hole. Short hole mining is similar to development mining, except that it occurs in ore. There are several different methods of long hole mining. Holes are drilled between the two excavations and loaded with explosives.

The holes are blasted and the ore is removed from the bottom excavation. One of the most important aspects of underground hard rock mining is ventilation. Ventilation is also used to manage underground temperatures for the workers. In deep, hot mines ventilation is used to cool the workplace; however, in very cold locations the air is heated to just above freezing before it enters the mine.

Ventilation raises are typically used to transfer ventilation from surface to the workplaces, and can be modified for use as emergency escape routes. The primary sources of heat in underground hard rock mines are virgin rock temperature, machinery, auto compression, and fissure water. Other small contributing factors are human body heat and blasting.

Some means of support is required in order to maintain the stability of the openings that are excavated. This support comes in two forms; local support and area support. Area ground support is used to prevent major ground failure. Holes are drilled into the back ceiling and walls and a long steel rod or rock bolt is installed to hold the ground together.

There are three categories of rock bolt, differentiated by how they engage the host rock. Local ground support is used to prevent smaller rocks from falling from the back and ribs.

Not all excavations require local ground support. Using this method, mining is planned to extract rock from the stopes without filling the voids; this allows the wall rocks to cave in to the extracted stope after all the ore has been removed. The stope is then sealed to prevent access. Where large bulk ore bodies are to be mined at great depth, or where leaving pillars of ore is uneconomical, the open stope is filled with backfill, which can be a cement and rock mixture, a cement and sand mixture or a cement and tailings mixture.

This method is popular as the refilled stopes provide support for the adjacent stopes, allowing total extraction of economic resources. The mining method selected is determined by the size, shape, orientation and type of orebody to be mined. The width or size of the orebody is determined by the grade as well as the distribution of the ore. The dip of the orebody also has an influence on the mining method for example a narrow horizontal vein orebody will be mined by room and pillar or a longwall method whereas a vertical narrow vein orebody will be mined by an open stoping or cut and fill method.

Further consideration is needed for the strength of the ore as well as the surrounding rock. An orebody hosted in strong self-supporting rock may be mined by an open stoping method and an orebody hosted in poor rock may need to be mined by a cut and fill method where the void is continuously filled as the ore is removed.

Orebodies that do not cave readily are sometimes preconditioned by hydraulic fracturingblasting, or by a combination of both.This site uses cookies to create a better experience for you. Other cookies are used for functional, performance, and targeting purposes to enhance your experience by personalizing content and ads, enabling third party content and features, and enabling us to analyze how this site is used.

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Simply enter your address and select the type of equipment you're looking for. Or, if you already know the name of the dealer you're searching for, you can type in the dealer's name for a list of locations. If you search for vocational trucks elsewhere you will not get any results. No two underground operations are the same—what, how and where you mine are unique.

Our underground systems are designed specifically for hard rock, as well as for longwall operations. It's a very quiet and well-balanced machine that's also highly aggressive in the pile.

BHP - Underground Mining School of Excellence

We've made it highly configurable for your mine - with 6 body options that include an ejector option, open and enclosed cab choices - and crucial safety features like operator present technology. Plowing is the preferred longwall mining technique for seams below 1. Today, Caterpillar is the market leader in the field of fully integrated and automated plow systems. The power of Caterpillar is more than iron. Would you like to be among the first to know about Cat mining news Then be sure to sign up for our monthly e-newsletter.

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Category:Underground mines in the United States

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underground mining line

All Location Types. Equipment Type Reset Filters. All Equipment Types. Electrical Power. Industrial And Rail Engines. Marine Engines.That is, no names, labels or descriptions are changed. Updates the names, labels, and descriptions of the fields in the dataset with respect to the original names in the source.

An entry keyed with the field id generated in the source for each field that you want the name updated. All the fields in the source. Specifies the fields to be included in the dataset. The first element is an operator and the rest of the elements its arguments.

See the section below for more details. Specifies the default objective field. Example: true size optional Integer,default is the source's size The number of bytes from the source that you want to use. Example: 500 You can also use curl to customize a new dataset with a name, and different size, and only a few fields from the original source.

If you do not specify a size, BigML. If you do not specify any fields BigML. This predicate is specified as a (possibly nested) JSON list whose first element is an operator and the rest of the elements its arguments. Here's an example of a filter specification to choose only those rows whose field "000002" is less than 3.

Note how you're not limited to two arguments. It's also worth noting that for a filter like that one to be accepted, all three fields must have the same optype (e.

The field operator also accepts as arguments the field's name (as a string) or the row column (as an integer). If you have duplicated field names, the best thing to do is to use either column numbers or field identifiers in your filters, to avoid ambiguities. Besides a field's value, one can also ask whether it's missing or not.

These are all the accepted operators: To be accepted by the API, the filter must evaluate to a boolean value and contain at least one operator. So, for instance, a constant or an expression evaluating to a number will be rejected.

Once a dataset has been successfully created it will have the following properties. This is the date and time in which the dataset was created with microsecond precision. It can contain restricted markdown to decorate the text. It has an entry per each field type (categorical, datetime, numeric, and text), an entry for preferred fields and an entry for the total number of fields.

underground mining line

That is the total number of fields including those created under the hood to support text fields. Each entry includes the column number, the name of the field, the type of the field, and the summary. In a future version, you will be able to share datasets with other co-workers or, if desired, make them publicly available. This is the date and time in which the dataset was updated with microsecond precision.

Dataset Fields The property fields is a dictionary keyed by each field's id in the source. Each field's id has as a value an object with the following properties: Numeric summaries come with all the fields described below.

If the number of unique values in the data is greater than 32, then 'bins' will be used for the summary. If not, 'counts' will be available. Categorical summaries give you a count per each category and missing count in case any of the instances contain missing values.And then there were two.

While Bernie Sanders is technically still running, Donald Trump v.

underground mining line

This lead may be surprisingly small to some people (Democrats) or surprisingly large to others (believers in fundamental models). A lot more to follow in the next 6 months and 4 days.

It has been so much fun, but there is a really good chance that the primary effectively ends in 30 minutes feeling nostalgic yet. A quick post on the state of the election at 191 until Election Day. Also, just added Newt Gingrich into the Republican VP slot should keep an eye on him. We pushed some updates to the site this morning. Musings will be brief updates on data, so I can reserve blog posts for more complete thoughts.

Our polling reflects bleeding-edge research into cost-effective, fast, flexible, and accurate polling with an emphasis on politics and finance. We infuse raw polling data with machine-learning-based post-polling analytics along with a host of other data. The backbone of predictions on this site are market-based, generated from real-money markets that trade contracts on upcoming events. PredictWise is run by David Rothschild an innovative, and stylish economist at Microsoft Research in New York City, but should in no way be construed as representing the views or predictions of Microsoft or any of its entities.

How do these match. Prior to the end of the primary strategic or upset party voters will state they will not vote for the other possible nominees.

That is helpful to their candidate. Clinton, but not vote or vote for Clinton v. Starting with the 2012 map, Clinton just needs to hold VA, OH, or FL. Pollster averages have her up by 12 pp in VA, 3 pp in OH, and 2 pp in FL. Real Clear has her up 13 pp in VA, 1. This tends to have some predictive power, in addition to polls, at this early point. Clinton has more money in the bank and will likely out raise Trump by a lot.

She will have a more unified GOTV game. And, she is extremely vetted. Trump, while in the public spotlight has not been vetted as closely (no one has). Politics When Will Trump Leave Office.


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