Mining: The Cobalt Example
Egypt, China, and eventually Europe used cobalt. Coined from “kobold” by Germans (for “goblin”), it was officially described by Swedish chemist Brandt in 1735, and in 1938 Livingood & Seaborg discovered Cobalt-60 isotope (“Co”), used famously at Columbia University in the 1950s to show “parity violation in radiaocative beta decay.”
With cobalt mines shifting in the 1800s from Scandanavia to New Caledonia, to Ontario/Canada, to Katanga Province (Congo), shortages were rare despite conflicts in the Congo (as much Cobalt could be recycled or substituted by another material). U.S. reserves found near Blackbird Canyon/Idaho led to the firm “Calera Mining Company” being started. It is important to remember that Co is often found as a by-product of Nickel & Copper mining activity.
Katanga in Congo remains the source of around 40% of the world’s Cobalt, and CAMEC (Central African Mining & Exploration Company) affiliated with Zhejiang Galico Cobalt & nickel Materials of China as a supplier in 2008. Through mainly chemical reactions, Cobalt is separated from ore components, and is used mainly in metal superalloys which confer incredible temperature stability (allowing use in gas turbines, jet aircraft – though not as strong as nickel alloys). Cobalt is used with titanium in medicine, for orthopedic implants. Other alloys (like chromium, tungsten, molybdenum) are used in implants. For dental implants, cobalt can substitute for patients who suffer from nickel allergy. Other alloys (Al-Ni-Co, or Alnico), and Samarium-Cobalt permanent magnets, as well as platinum-Co jewelry, also exist. Cobalt oxide with intercalated Lithium (LiCoO2) with Li set free during discharge between CoO2 layers, as well as use in Nickel doing the same (NiMH, or Nickel metal hydride) are useful in batteries. Other uses in chemical reactions are noted for cobalt.
Smalt, a blue-colored glass, is made by combining the roasted mineral smaltite, quartz, and potassium carbonate. Cobalt green and cobalt blue use followed (especially in paintings).
Mining, or removal of geological materials from earth (via ore body, vein/coal seam), can be done for base metals, precious metals, coal, diamonds, limestone, non-renewable resources such as petroleum, natural gas, or water. Dating to pre-historic times for fashioning weapons, the oldest known mines are reportedly “Lion Cave” in Swaziland, Africa (hematite for red pigment), Egyptians for green malachite stones, and then Athens and Rome. Romans developed “hushing” – building a reservoir to flood the “overburden” to expose bedrock and gold veins, then fire-setting to heat the rock to “shock” it and
Such methods were undertaken in Spain and England (for gold, silver, tin, or lead, for example). Using “adits” driven through barren rocks, the mining areas were ventilated for fire-setting, using reverse overshot water-wheels (on a treadmill based operation), for copper and other metals.
In the middle ages, mining for copper and iron ore for weapons/armor (upto 100 lbs per knight) with introduction of “black powder” for blasting, via Hungary. Processing was done by arrastra, like threshing grain;
In North America, native Americans mined copper about 5000 years ago, for weapons and tools; quartz mines also existed. Copper, gold, and turquoise were mined as well, with gold preferable as it did not require smelting (i.e. the process of removing other mixed-in or bound substances, by heating, chemical reaction, or both, as for example CO is used to take away oxygen to form CO2).
While conditions have improved somewhat, significant peril still is present in the mining industry today.
Often, the initial process involves a feasibility study (e.g. to determine presence of the enrichment factor of ore) regarding whether the project should proceed. Surface mining, used for over 85% of metals and ores, accesses either placer (within loose material) or lode (within hard rock, e.g. within a vein) material. Recovery techniques are then used.
Rarer mining, such as uranium mining, are done using a solvent. Strip mining (taking off strips) or mountaintop mining (for coal, usually) is also done. Sub-surface mining (drift – horizontal; slope – diagonal; and shaft – vertical) in hard and soft rock are used. Room and pillar mining (with destruction of pillars, allowing the room to cave in, loosening more metal) offers other techniques.
Environmental erosion may occur in combination with sinkholes (sometimes in combination with logging, to help store debris from mining). Based upon self-policing and other institutions, regulations are enforced to help minimize environmental deterioration.
A large amount of waste (e.g. 99 tons of waste per 1 ton of copper mined – with a higher ratio for gold mining (!)) results, known as “tailings” – these can be toxic, are contained in ponds with dams, and can occasionally cause a disaster and empty into local rivers or other water sources. Though submarine tailing emptying has been proposed by mining industry as “ideal” it is banned in U.S. & Canada, but allowed in developing nations.
Banks have also been significantly involved since 1955 in mining, as exemplified by the World Bank’s provision of over $2B; also, privatization has been encouraged for national mines, with some regulations (which have fallen short in some cases, per opinions). Regulations in smaller countries, with “artisanal” mines where transparency may not be as good, are difficult to monitor.
Industrial mining capitals globally involve London (Rio Tinto, BHP Billiton, Angio American PLC), US (coal and non-metal minerals). Of the global market cap of 50 trillion (USD), US compares at 962B. Due to large CapEx, most mining is done by multi-national, large teams. Exploration is carried out by smaller groups such as individuals or mineral resource companies called “juniors” backed by VCs, and actual mining companies (larger companies). Countries interested in mining (e.g. Canada) have special stock exchanges focusing upon funding mining activity.
Two classification schemes for mining operations can exist – (1) by category — oil & gas/coal/metal ore/nonmetallic mineral mining & quarrying/support services for mining. Seismic prospecting and remote-sensing satellites are techniques used to help exploration, particularly with oil & gas; (2) by size – major (Rev > 500m USD); intermediate (50mm – 500mm); and junior (equity-financed, mainly exploration, <50mm).
Interestingly, copper forms the basis of many statues – including the Statue of Liberty. One of the other more striking examples is the large statue amidst the hills of Buddha, which is located near Hong Kong airport.
Mining Cobalt for The Brain: A Special Case Study
Cobalt is found naturally only in a chemical combination with other elements, with the pure (free) element produced by smelting (reduction, interestingly giving off Arsenic, a poisonous vapor) and appearing as a hard, shiny, sliver-gray metal. Discovered in 1735, Cobalt-rich areas include “copper belt regions” of the Congo & Zambia. Cobalt is used in alloys, blue glass/ceramics/paints/etc. coloring, and Cobalt-60 is used as an isotope radioactive tracer to produce gamma rays (e.g. in Gamma knife radiosurgery). It occurs in co-enzymes (cobalamins, e.g. Vit B12), and is a essential trace mineral for animals, bacteria, and fungi.
Cobalt can exist as different types: oxides (green, brown, blue), halides (pink, blue, green, blue-black, & red for hydrated), and enantiomers (optical isomers) which give crystals. Cobalt-59 is the only stable isotope in nature, but Cobalt-60 has a half-life little over 5 years.
Radioisotopes: Cobalt-60 use as a gamma ray source (when bombarded by neutrons) has been used for external beam radiotherapy/Gamma Knife, cold pasteurization, and radiography (with discarding needing to be done very carefully, due to the extreme cobalt dust toxicity). It is also used in the Schilling test (for B12 deficiency, intrinsic factor (?)). Interestingly, its lack can cause “bush sickness” in ruminants (e.g. cows), cured by adding Co to fertilizer, but for non-ruminants, they rely upon digesting feces (as bacteria must produce the Vitamin B12, as Cobalt cannot directly be absorbed and converted by these animals). At higher levels, cobalt can be poisonous.
The goal of Cobalt as a gamma generator for the Gamma Knife, for example, is that multiple particles converge on a central target (e.g. a brain tumor) with minimal damage to the surrounding brain. Hence, the implications of cobalt mining are significant – even involving the human brain! In A Gamma Knife, for example, 201 “beams” using Cobalt as a source converge upon a focused region of target tissue, minimizing radiation to the surrounding brain (similar to placement of a hand between the magnifying glass under direct sunlight and the ground, where the hand does not become burned but the paper below where the rays focus may).
Special handling considerations must be employed for Cobalt – its use is indeed unique due to its radioactive properties; hence it remains essential to be able to aid many today.
(Information contained here was acquired from multiple sources, including discussions, reading, and websites such as pwc.com, miningindustryreview.com, and/or Wikipedia.org)