Borehole mining
Encyclopedia
Borehole Mining (also referred to as jet-boring) is a remote operated method of extracting (mining
) mineral resources through borehole
s by means of high pressure water jets. This process can be carried-out from land surface, open pit floor, underground mine or floating platform or vessel
through pre-drilled boreholes.
pipes
which are forming two hydraulic channels - one for pumping down a high-pressure working agent (water
) and second for delivering pregnant slurry
back to the surface. A BHM tool usually has (down-up): an eductor (waterjet pump) section, a hydromonitor section, an extension section and a hub, connecting it all to a drill pipe string. This string extends the tool up to the surface. Above the surface, the tool has a swivel allowing its suspension
and rotation in a hole, and also connections to the working agent supply (pump station) and a slurry collector. A drill rig is normally required to operate a BHM tool.
The tool is lowered into a well
until the hydromonitor reaches the required depth where the actual borehole mining is started. Then the high-pressure water is pumped down and receives back productive slurry. In the collecting pond or tank, slurry is separated and clarified water is pumped down for re-circulating.
While extracting of material, different shape underground caverns could be created. Their shapes depend on the BHM tool manipulation while mining, which obviously consist of the tool rotation, sliding it up and down and combination of these two movements. Borehole mining is applied from vertical, horizontal and deviated wells.
cost, mobility, selectivity, ability to work in hazardous and dangerous conditions and low environmental impact. The method has been used in mining of such natural resources and industrial materials as: uranium
, iron ore, quartz sand, gravel, coal, poly-metallic ores, phosphate
, gold, diamonds, rare earths, amber
and several more. Borehole mining is also used in exploration, oil
, gas and water stimulation, underground storage construction and drainage.
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...
) mineral resources through borehole
Borehole
A borehole is the generalized term for any narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water or other liquid or gases , as part of a geotechnical investigation, environmental site...
s by means of high pressure water jets. This process can be carried-out from land surface, open pit floor, underground mine or floating platform or vessel
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...
through pre-drilled boreholes.
The process
- A borehole is drillDrillA drill or drill motor is a tool fitted with a cutting tool attachment or driving tool attachment, usually a drill bit or driver bit, used for drilling holes in various materials or fastening various materials together with the use of fasteners. The attachment is gripped by a chuck at one end of...
ed from land surface to a desired depth, where then actual borehole mining will take place. - A casing column is lowered down the hole. Since BHM takes place in an "open hole", the casing shoeCasing shoeIn oil drilling and borehole mining, a casing shoe or guide shoe is a bull-nose shaped device which is attached to the bottom of the casing string. A casing hanger, which allows the casing to be suspended from the wellhead, is attached to the top of the casing....
is located just above the upper border of the productionMass productionMass production is the production of large amounts of standardized products, including and especially on assembly lines...
interval (oreOreAn ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....
body) leaving the rest open. - The BHM tool is lowered into the hole.
Description of a BHM tool
The tool consists of at least two concentricConcentric
Concentric objects share the same center, axis or origin with one inside the other. Circles, tubes, cylindrical shafts, disks, and spheres may be concentric to one another...
pipes
Pipe (material)
A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow — liquids and gases , slurries, powders, masses of small solids...
which are forming two hydraulic channels - one for pumping down a high-pressure working agent (water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
) and second for delivering pregnant slurry
Slurry
A slurry is, in general, a thick suspension of solids in a liquid.-Examples of slurries:Examples of slurries include:* Lahars* A mixture of water and cement to form concrete* A mixture of water, gelling agent, and oxidizers used as an explosive...
back to the surface. A BHM tool usually has (down-up): an eductor (waterjet pump) section, a hydromonitor section, an extension section and a hub, connecting it all to a drill pipe string. This string extends the tool up to the surface. Above the surface, the tool has a swivel allowing its suspension
Suspension (chemistry)
In chemistry, a suspension is a heterogeneous fluid containing solid particles that are sufficiently large for sedimentation. Usually they must be larger than 1 micrometer. The internal phase is dispersed throughout the external phase through mechanical agitation, with the use of certain...
and rotation in a hole, and also connections to the working agent supply (pump station) and a slurry collector. A drill rig is normally required to operate a BHM tool.
The tool is lowered into a well
Well drilling
Well drilling is the process of drilling a hole in the ground for the extraction of a natural resource such as ground water, natural gas, or petroleum...
until the hydromonitor reaches the required depth where the actual borehole mining is started. Then the high-pressure water is pumped down and receives back productive slurry. In the collecting pond or tank, slurry is separated and clarified water is pumped down for re-circulating.
While extracting of material, different shape underground caverns could be created. Their shapes depend on the BHM tool manipulation while mining, which obviously consist of the tool rotation, sliding it up and down and combination of these two movements. Borehole mining is applied from vertical, horizontal and deviated wells.
Advantages of BHM
The main advantages of BHM include its low capitalCapital (economics)
In economics, capital, capital goods, or real capital refers to already-produced durable goods used in production of goods or services. The capital goods are not significantly consumed, though they may depreciate in the production process...
cost, mobility, selectivity, ability to work in hazardous and dangerous conditions and low environmental impact. The method has been used in mining of such natural resources and industrial materials as: uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
, iron ore, quartz sand, gravel, coal, poly-metallic ores, phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
, gold, diamonds, rare earths, amber
Amber
Amber is fossilized tree resin , which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. There are five classes of amber, defined on the basis of their chemical constituents...
and several more. Borehole mining is also used in exploration, oil
Oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
, gas and water stimulation, underground storage construction and drainage.