Mining from A to Z

Amphibolites
Rock

Amphibolite is a metamorphic rock. The main components are amphiboles (mostly hornblende) and plagioclase. Quartz, garnet, diopside, epidote and biotite may also be present. The chemical composition of the amphibolites is metabasic. They are obtained from basic magmatites such as gabbros, basalts, andesites and their tuffs or from marls and tuffites (para-amphibolites)

 

Angle of repose (slope)
Bulk materials property

For cohesion-free, free-flowing, grainy materials such as grain, granulated mineral fertilizer, limestone, pellets, coke, etc., the natural angle of repose – also known as the angle of slope – is the maximum angle at which individual surface particles stop sliding down. The natural angle of repose can be easily determined by allowing the bulk material to flow from the base area of a cylinder-shaped sampler at low tipping height onto a firm horizontal support.

 

Anthracites
Bituminous coal

Anthracite is a bituminous coal with a volatile content of less than ten percent. This high-grade form of coal is extremely hard. Anthracite forms from vegetable matter under high pressure and in the absence of air. This increases the carbon content. This lies at over 91.5 percent by weight. Anthracite is particularly prized as a fuel due to its high energy content, the hot flame it produces and its combustion properties which mean that it leaves almost no residue.

Backfill
Cavity filling

In mining, the term backfilling refers to the filling-in of the cavity between the excavated area and the rock mass using suitable materials. Various materials (such as gravel) and a number of different technologies are used for backfilling.

 

Ball mill
Grinding of ore

A ball mill is a mill for ultrafine grinding or homogenization. It consists of a rotating grinding jar (steel cylinder) into which the material to be ground (ore) is fed. Grinding balls made of various materials are added – in the case of ore, the balls are made of steel. Rotation of the ball mill pulverizes the ore.

 

Banded iron formation
Sedimentary rock

Banded iron formations are units of iron-bearing marine sedimentary rock that were primarily deposited in the Precambrian period. They possess a characteristic banded structure due to their metal-bearing layers. The layers primarily consist of ferrous minerals with a vertical cross-section reminiscent of bands. This is what gives them their name.

 

Basalt
Igneous rock

Basalt is a basic igneous rock. It consists in particular of iron and magnesium silicates with pyroxenes and calcium-rich feldspar (plagioclase) and also usually also olivine. Basalt is the volcanic equivalent of gabbro (plutonite), which has the same chemical composition. Basalt is usually dark gray to black. Because the rock is formed through the action of volcanic processes, the groundmass is usually fine-grained due to the rapid cooling it undergoes.

 

Base metal
Base metal

Base metals are characterized by the fact that they oxidize – under normal conditions they react with oxygen in the air. For example, iron rusts. Zink and aluminum protect themselves through passivation, which is the formation of a corrosion-resistant oxide layer that prevents further oxidation. Base metals differ chemically from noble metals in that their redox pairs have a negative instead of a positive standard electrode potential (relative to the standard hydrogen electrode).

 

Bauxites
Aluminum ore

Bauxite is an aluminum ore that consists primarily of the aluminum materials gibbsite (hydrargillite) and diaspore as well as the iron oxides haematite and goethite, the clay material kaolinite and small amounts of the titanium oxide anatase. Bauxite takes its name from its place of discovery, Les Baux-de-Provence in the south of France. It was unearthed there for the first time in 1821.

 

Belt conveyor
A system for moving bulk material

Machine which transports bulk material on a conveyor belt. It mainly consists of a supporting structure made of steel sections, a drive station, a return station, idlers and a conveyor belt.

 

Belt wagons
Mining technology

Belt wagons are standalone machines built on crawlers which serve to transport and discharge the overburden or minerals. In opencast mining these machines are very important links for continuous excavating, transporting, and discharging activities especially when mining and dumping areas are spread apart over significant distances.
The belt wagons help save on overall investments and operating costs which otherwise would be substantially higher due to the need to acquire larger main equipment.

 

Blending bed
Stockyards

Numerous bulk materials handling applications require process-compatible treatment of the material. Their chemical and physical properties should be as homogeneous as possible. Since most of these materials come from quarries or opencast mines, their properties may vary enormously and so stockyards have to meet much higher standards. A stockyard designed not only as a buffer or to hold back-up stocks but also for homogenizing material properties is known as a blending bed. Such a facility ensures blending or pre-homogenization by combining a specific stacking technology with a particular type of reclaiming technology.

Generally speaking, the material is stacked in consecutive layers, and depending on the type of reclamation, individual, several or all of the layers are reclaimed at the same time. The efficiency of such a blending bed is expressed as the homogenizing effect, generally also denoted as the blending effect.

 

Block caving
Mining of ore

Block caving is an underground mining method in hard rock in which an ore body is undercut until it finally collapses under its own weight. This can cause the formation of large surface depressions called dolines or sinkholes. The method is an economical means of mining large ore deposits.

 

Bridge-type reclaimers
Stockyard machines

Bridge-type reclaimers are exclusively employed in face reclamation. A bridge girder is used for the supporting structure. The scraper chain is located underneath the bridge girder. Harrow-type carriages with harrow arms are mounted on the bridge structure on either one or both sides. Their shape is adapted to the cross-section of the stockpile. The bridge girder spanning the entire foot width of the stockpile is supported on a rail-borne undercarriage. By moving the harrow carriage in reverse, the harrow arm, which is supported on the face side of the stockpile, loosens the bulk material. As a result, the bulk solids trickle down to the foot of the stockpile on the slope surface. Here they are picked up by the scraper chain and transferred to a belt conveyor for discharging.

In circular stockyards, bridge-type reclaimers, which rotate via a slew column around a central axis, are employed. In this arrangement, the bridge girder’s outer point with the undercarriage is supported on a ring rail.

Bridge-type reclaimers are also known as blending bed installations because they produce the best homogenizing effects in bulk solids reclaiming. This homogenizing effect is produced by the work of the harrow arm traveling transversely to the stockpile, thus pre-blending the bulk solids from various layers of the stockpile. Subsequently, the bulk material is mixed again by the scraper shovels on the stockpile foot. The harrow can reach all the layers on the stockpile’s face side and remove them at uniform depth.

The use of bridge-type reclaimers with scraper chains is limited by the properties of the bulk material. Slow-flowing bulk materials can be reclaimed only very slowly (if at all). In such cases, bridge-type machinery with a bucket wheel or bucket chain are used.

 

Bucket elevator
Vertical transport of powdery or small-sized bulk material

A continuous conveyor for vertically elevating powdery or small-sized bulk material. The buckets are attached to a double- or single-strand chain, a pintle chain or a belt. Vertical continuous conveyor with buckets used as support elements that scoop the material to be transported or are filled and emptied in certain areas. Belts or chains are used as traction elements.

 

Bucket wheel reclaimers
Stockyard machines

Bucket wheel reclaimers equipped with a bucket wheel boom are used on stockyards to reclaim large mass flows of poorly flowing bulk solids or bulk materials of relative high density. The design principle and function of bucket wheel reclaimers are not essentially different from those of the bucket wheel excavators used in opencast mines. However, the cutting forces required on the bucket wheel and the mass flows to be achieved are usually somewhat higher in opencast mining. Bucket wheel reclaimers mostly consist of a slewable superstructure and a rail-mounted sub-frame. Both the bucket wheel boom and the counterweight boom are hinge-mounted on the superstructure and guyed by guy ropes or tiebacks via a pylon. The bucket wheel boom is raised or lowered with the help of cable winches or hydraulic cylinders. The bucket wheel, which is mounted eccentrically on the wheel boom head, picks up the bulk material and transfers it laterally to the boom conveyor. The belt conveyor transports the bulk solids to the central chute in the superstructure slewing axis, from where the material is transferred to a discharging stockpile conveyor running between the rails of the reclaimer. In order to achieve potentially large clearance angles and good bucket cutting, filling and emptying, the bucket wheel is mounted so that it is not only turned torsionally around a vertical axis, but also tilted around a horizontal axis arranged at right-angles to the wheel shaft.

Furthermore, crawler-mounted compact-type bucket wheel excavators are also employed as reclaimers. They are characterized by a particularly favorable unit weight. They are very flexible and can be used for many applications. Reclaimers of this type have a relatively short bucket wheel boom that can be hydraulically raised and lowered, and for reclaiming stockpiles in block operation they are equipped with slewing gear for the superstructure and a separately slewable discharge boom. The short wheel boom requires only a small counterweight outreach. This counterweight is positioned on the superstructure platform extended toward the rear such that the discharge boom can be slewed above it. The wheel boom is supported in the pylon of the superstructure above the feeding chute of the discharge belt conveyor.

Besides this design, which is typical of compact-type excavators, modified compact-type bucket wheel reclaimers on crawlers without a separate discharge boom are built for specific applications. In this case the material is transferred by a continuous belt conveyor without any intermediate transfer from the bucket wheel to the discharge point of the machine. Compact-type bucket wheel reclaimers without separate discharge booms are used solely in bench-type operation. Compared to the compact-type bucket wheel excavators with separate discharge boom, the steel structure of these machines’ superstructure is of a simpler, lighter design. There is no material transfer point in the center of the device, which is an additional benefit in connection with abrasive materials such as copper ore.

 

Bulk materials handling
What industry needs

Bulk materials handling denotes the change-over between the different means of transport in the transport chain from the place of extraction to the place of processing or the consumer. A wide variety of means of transport can be employed in the transport chain, including trucks, railway wagons, seagoing vessels and inland barges. The handling process comprises the loading and unloading of the means of transport. Selection of the handling equipment to be used depends primarily on the properties of the bulk materials, the volume to be handled per unit time (mass flow) and the type of transport. Furthermore, the environmental regulations in force, particularly regarding dust and noise emissions (especially at ports and freight depots) have to be met. As handling systems are often an interface in freight transport, they need to meet certain demands in connection with the testing and quantity measurement of the bulk solids shipped or supplied.

 

Bulk material
A granular or fragmented mixture in pourable form

Bulk materials are different kinds of lumpy, granular and powdered products like e.g. ores, coal, peat, sand, saw dust, cement. Accord. to VDI 2411 bulk materials are “loose, pourable materials to be conveyed”.

 

Bulk terminal
Transshipment port for bulk goods

The area of a port used for transshipment of bulk goods. The warehouse capacities, loading equipment and packaging facilities are designed for handling bulk goods.

Chromite
Ore mineral

Chromite is a mineral belonging to the oxides. Chemically it is an iron chromium oxide. It typically occurs in granular to massive aggregates. The color is usually black, but rarely also dark brown. The surface has a greasy metallic luster.

 

Conveying and Loading
Conveying and loading of bulk materials along the entire process chain

Ores, salts, rocks, earth and other resources that have been mined must be transported over long distances. After extraction and crushing, the material must pass through stations like grinding, flotation, drying, homogenization, mixing, interim storage and loading. Conveyor systems have to ensure safe, efficient and environmentally friendly handling of these materials along the entire process chain.

 

Conveyor
Efficient and environmentally friendly handling system for bulk material along the entire process chain

Also called conveyor system, belt system or belt conveyor. Means of transporting granular or fragmented cohesive or non-cohesive material or piece goods. These systems transport all kinds of bulk material in a wide variety of industrial sectors.

Mining industry
Extraction of mineral resources

Extraction of useful mineral resources like ores, coal, copper, rocks or earth in compliance with special legislation (mining law). This is done in open-pit mining or underground mining with the help of special machinery and equipment.

Overland conveyor
A belt conveyor for overland transport of bulk material

(see belt conveyor). A conveyor for continuous overland (long-distance) transport of bulk material to a storage location such as a stockpile. From there the material can be taken up by railroad cars or trucks for further processing. Overland conveyors are used wherever large quantities of bulk material must be transported in an efficient and environmentally manner from A to B.

Ship loader
Port handling

Decisive factors when selecting and sizing a ship loading system are the bulk material properties, the local conditions, the performance parameters and the environmental requirements. Taking all these aspects into consideration, the most effective and cost-efficient handling principle requiring a minimum of operation and maintenance needs to be worked out. The loading system must be adapted to the port infrastructure and must be coordinated to suit current and future ship sizes.

Ship loaders working in continuous mode to load the cargo holds of a vessel generally consist of a portal and a superstructure with a boom that can be raised or lowered. The loading device is located at the head of the boom. In the case of loose bulk solids, a telescopic chute or a loading tube is used for loading. To handle bulk materials, telescopic chutes are frequently equipped with a dust collection device. A ship loader’s superstructure can be slewable or non-slewable.

Depending on the nature of the port terminal, ship loaders are either in stationary design or are movable in longitudinal direction or radially. Stationary ship loaders have a slewable superstructure and are used primarily in inland ports. During loading, the ship to be loaded must be moved so that the ship loader can fill the entire cargo hold.

Longitudinally movable ship loaders are the most frequently used. They are employed both in inland and seaports. While a stationary ship loader is supplied directly by a belt conveyor, ship loaders moving alongside the quay have to be operated in combination with a tripper car.

Tubular conveyor
Conveyor technology

Closed pipe conveyers reliably move products while protecting them from external influences and preventing the escape of dust. Bulk material can be transported downhill in closed belts. Different materials can be conveyed in the top strand and bottom strand.

Vertical transport
Conveyor technology

In vertical transport, belt bucket elevators reliably convey powdery to coarse-grained bulk materials like limestone, coal and ores to heights of 200 meters and more. The materials can be fed to the bucket elevator in a space-saving manner from below or directly via a chute. Specially designed buckets are available in different widths, depending on the application and the quantity to be conveyed. Belt bucket elevators are also suitable for conveying hot bulk materials.

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