Mine caps are typically used to prevent access to old, abandoned mines. People, especially the young, like to explore their surroundings but may not fully understand the dangers inherent within, and surrounding, a mine. [1]
Cave-ins, poor air quality, wet slippery surfaces, etc. are real dangers when entering a mine, but even the surrounding area can be dangerous. Older mines may have been covered with logs or wooden beams with loose rock and soil over the top. [1] These fail over time, creating sinkholes, that may not be visible on the surface, until enough weight collapses it.
Federal and State laws dictate certain aspects in the capping process, such as allowances for bats to have access. The type of mine, water table, geology, etc. are all considered when choosing which type of cap will be used for a given mine entrance.
Concrete continues to be the preferred method for capping vertical shafts. Considerations can be made in the design to allow for an entrance to the mine, a steel door for humans, a slot for bats, a hole for airflow. The slab thickness can vary from as little as 6 inches to several feet.
Expanding foam is quickly replacing concrete for some vertical shafts, typically mines where an entrance for humans is no longer desired. This type of cap is sometimes referred to as a "Plug." Plugs usually have a taper to them, smaller on the bottom and wider on the top, like the cork on a wine bottle. Expanding foam plugs need to be quite thick, usually no less than 6 feet deep. Typically, loose rock and soil is placed over the top.
A steel grate may be used to cover the mine adit or shaft. This has the advantage of allowing mine gas to ventilate, water to drain from horizontal adits, and bats to traverse the grate. [1]
1/4 inch or thicker steel-plating is also used, on both horizontal and vertical shafts. These allow for easier customization than concrete, cutting access holes in steel is far easier than building the concrete forms necessary for the same result. This type of cap is used where easy access is a necessity.
The photo at right is of a 1/4-inch steel-plating cap at the entrance to a horizontal shaft at the Petherick Mine, located in Keweenaw County, Michigan. The slot cut near the top of the plate allows bats to enter and exit.
A 19-inch rack is a standardized frame or enclosure for mounting multiple electronic equipment modules. Each module has a front panel that is 19 inches (482.6 mm) wide. The 19 inch dimension includes the edges or ears that protrude from each side of the equipment, allowing the module to be fastened to the rack frame with screws or bolts. Common uses include computer servers, telecommunications equipment and networking hardware, audiovisual production gear, music production equipment, and scientific equipment.
Underground hard-rock mining refers to various underground mining techniques used to excavate "hard" minerals, usually those containing metals, such as ore containing gold, silver, iron, copper, zinc, nickel, tin, and lead. It also involves the same techniques used to excavate ores of gems, such as diamonds and rubies. Soft-rock mining refers to the excavation of softer minerals, such as salt, coal, and oil sands.
A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, sand or rock dust.
An adit or stulm is a horizontal or nearly horizontal passage to an underground mine. Miners can use adits for access, drainage, ventilation, and extracting minerals at the lowest convenient level. Adits are also used to explore for mineral veins. Although most strongly associated with mining, the term adit is sometimes also used in the context of underground excavation for non-mining purposes; for example, to refer to smaller underground passageways excavated for underground metro systems, to provide pedestrian access to stations, and for access required during construction.
Stairs are a structure designed to bridge a large vertical distance between lower and higher levels by dividing it into smaller vertical distances. This is achieved as a diagonal series of horizontal platforms called steps which enable passage to the other level by stepping from one to another step in turn. Steps are very typically rectangular. Stairs may be straight, round, or may consist of two or more straight pieces connected at angles.
Siding or wall cladding is the protective material attached to the exterior side of a wall of a house or other building. Along with the roof, it forms the first line of defense against the elements, most importantly sun, rain/snow, heat and cold, thus creating a stable, more comfortable environment on the interior side. The siding material and style also can enhance or detract from the building's beauty. There is a wide and expanding variety of materials to side with, both natural and artificial, each with its own benefits and drawbacks. Masonry walls as such do not require siding, but any wall can be sided. Walls that are internally framed, whether with wood, or steel I-beams, however, must always be sided.
A concrete block, also known as a cinder block in North American English, breeze block in British English, concrete masonry unit (CMU), or by various other terms, is a standard-size rectangular block used in building construction. The use of blockwork allows structures to be built in the traditional masonry style with layers of staggered blocks.
A socket wrench is a type of spanner that uses a closed socket format, rather than a typical open wrench/spanner to turn a fastener, typically in the form of a nut or bolt.
Mine closure is the period of time when the ore-extracting activities of a mine have ceased, and final decommissioning and mine reclamation are being completed. It is generally associated with reduced employment levels, which can have a significant negative impact on local economies. It is also the period when the majority of mine reclamation is completed, making the land safe and useful again.
Insulating concrete form or insulated concrete form (ICF) is a system of formwork for reinforced concrete usually made with a rigid thermal insulation that stays in place as a permanent interior and exterior substrate for walls, floors, and roofs. The forms are interlocking modular units that are dry-stacked and filled with concrete. The units lock together somewhat like Lego bricks and create a form for the structural walls or floors of a building. ICF construction has become commonplace for both low rise commercial and high performance residential construction as more stringent energy efficiency and natural disaster resistant building codes are adopted.
Shaft mining or shaft sinking is the action of excavating a mine shaft from the top down, where there is initially no access to the bottom. Shallow shafts, typically sunk for civil engineering projects, differ greatly in execution method from deep shafts, typically sunk for mining projects.
A garage door is a large door to allow egress for a garage that opens either manually or by an electric motor. Garage doors are frequently large enough to accommodate automobiles and other vehicles. The operating mechanism is usually spring-loaded or counterbalanced to offset the door's weight and reduce the human or motor effort required to operate the door. Less commonly, some garage doors slide or swing horizontally. Doors are made of wood, metal, or fiberglass, and may be insulated to prevent heat loss.
Mine exploration is a hobby in which people visit abandoned mines, quarries, and sometimes operational mines. Enthusiasts usually engage in such activities for the purpose of exploration and documentation, sometimes through the use of surveying and photography. In this respect, mine exploration might be considered a type of amateur industrial archaeology. In many ways, however, it is closer to caving, with many participants actively interested in exploring both mines and caves. Mine exploration typically requires equipment such as helmets, head lamps, Wellington boots, and climbing gear.
A deep foundation is a type of foundation that transfers building loads to the earth farther down from the surface than a shallow foundation does to a subsurface layer or a range of depths. A pile or piling is a vertical structural element of a deep foundation, driven or drilled deep into the ground at the building site.
Mechanical screening, often just called screening, is the practice of taking granulated or crushed ore material and separating it into multiple grades by particle size.
Pallet rack is a material handling storage aid system designed to store materials on pallets. Although there are many varieties of pallet racking, all types allow for the storage of palletized materials in horizontal rows with multiple levels. Forklift trucks are usually required to place the loaded pallets onto the racks for storage. Since the Second World War, pallet racks have become a ubiquitous element of most modern warehouses, manufacturing facilities, retail centers, and other storage and distribution facilities. All types of pallet racking increase storage density of the stored goods. Costs associated with the racking increases with increasing storage density.
In mechanical engineering, a key is a machine element used to connect a rotating machine element to a shaft. The key prevents relative rotation between the two parts and may enable torque transmission. For a key to function, the shaft and rotating machine element must have a keyway and a keyseat, which is a slot and pocket in which the key fits. The whole system is called a keyed joint. A keyed joint may allow relative axial movement between the parts.
Stoping is the process of extracting the desired ore or other mineral from an underground mine, leaving behind an open space known as a stope. Stoping is used when the country rock is sufficiently strong not to collapse into the stope, although in most cases artificial support is also provided.
The Austin 25-30 is a motor car. It was the first automobile produced by newly established British car manufacturer Austin.
A bullet trap is a device to stop and collect projectiles fired at a shooting range to prevent overpenetrations and stray shots. Bullet traps typically use friction, impact or gradual deceleration to stop bullets. They can function as a backstop by themselves or be part of a larger backstop, e.g. placed in front of a thick rubber wall or a bay of sand.