Lead-Ore Extraction, Impacts, and Long-term Sustainability
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Table of Contents
Quantity and Location of World Resource: 3
Primary method and Secondary method. 4
Environmental Impact of Refining: 8
Introduction:
According to Fischman (2016), Lead is defined as a post-translational metal possessing atomic number 82 and is symbolized as Pb having a Latin origin plum bum. When it is freshly cut, it is light blue in color and smudges to cloudy gray when turned open to air. Its dominating characteristics include softness, malleability. It is referred a very heavy metal whose density surpasses the density of the most metals. It is an amphoteric element, it means to lead and its oxides can undergo reaction with acids as well as and they bases and have a propensity to form covalent bonds with other elements. Unlike carbon compounds, lead compounds usually have an oxidation state of +2 rather than +4. Resembling the most of the members with lighter molecular weight, lead exhibits the tendency for binding it to itself; creating long chains, rings, and polyhedral structures. Under the Goldschmidt classification, it is classified as a chalcophile and is found generally in combination with sulphur. It is considered as the 38th element found in abundance present on the earth crust (Laurence, 2011).
History:
Between 7000–6500 BC, lead Metallic beads were found in Asia and signify first ever most image of smelting of metal. The major cause of its widespread was its occurrence with silver, which can be attained by scorching Galena, which is the most widely occurring mineral of lead. Silver in combination with lead was broadly used for the construction of decorative materials such as sculptures. Lead deposits were originated at different eras as it was found in Asia Minor since 3000 BC. It was also being coined by Phoenicians at Iberian Peninsula since 2000 BC and before Phoenicians mining lead occurred at Greece, Cyprus, and Sicily by 1600 BC (Mills, Simpson and Adderley, 2014) Lead-Ore Extraction.
Origin and Occurrence:
The occurrences of lead have been increased in the Solar System to about 0.75% since its formation some 4.5 billion years before. The abundance table of solar system reveals that lead is the most prevalent element as compared to other elements having an atomic number greater than 40 (Mills, Simpson and Adderley, 2014).
Quantity and Location of World Resource:
Lead-Ore Extraction The aggregated quantity in the Earth’s layer is approximately 0.0016%, and the reserves are ample. According to the U.S. Geological Survey held in 2014, its current capacity of worlds reserve is far more than 2 billion tonnes, and Pb reserve capacity is stated to be 89 million tonnes. In natural surroundings, lead possessions occur essentially in the form of complementary mineral deposits, with the ore deposit containing largely lead together with the single lead deposits accounting for only 32.2% of the total reserves. Its per-particle occurrence in the Solar System was reported as 0.12 parts per billion (Fischman, 2016). The quantity of lead in the universe is slowly increasing as heavier atoms which are naturally unstable, gradually decay to lead.
Table 1: Reserves (in Thousands and metric tonnes of Pb)
| Country | Quantity |
| Australia | 36,000 |
| United States | 5000 |
| China | 14,000 |
| Ireland | 600 |
| Canada | 450 |
| Bolivia | 1,600 |
| India | 2,600 |
| Poland | 1,700 |
| South Africa | 300 |
| Peru | 7,500 |
| Mexico | 5,600 |
| Sweden | 1,100 |
| Russia | 9,200 |
| Other Countries | 3,000 |
| WORLD TOTAL | 89,000 |
(Source: Fischman, 2016).
Country Distribution:
The lead reserves of these six countries cover 85% of total reserves in the world. The lead assets are found to be higher in the following nations:
Lead-Ore Extraction Rome’s regional amplification in the Mediterranean and across Europe, and its growth in mining made it the utmost manufacturer of lead throughout the conventional era, with a predicted annual throughput of 80,000 tonnes. Like their forerunners, Romans acquired lead naturally as a by-product during silver smelting. Lead mining occurred in Central Europe, the Balkans, Britain, Greece, Hispania and Anatolia. Lead is being produced by two ways either primary or secondary method (Fischman, 2016).
Primary method and Secondary method
Primary production involves the production of lead mainly from mines while secondary production involves its production from raw products or from residues that arise during production processes of ores. In the United States, 80% of lead originates through secondary sources while Europe reporting over 60% of lead from a secondary source (Harrison, 2012).
In the New World, it was produced soon after the arrival of European settlers. The earliest recorded lead production dates to 1621 in the English Colony of Virginia, fourteen years after its foundation .In 1841, in Australia, the first mine opened by colonists on the continent was a lead mine. In Africa, lead mining and smelting were identified in the Benue Trough and the lower Congo basin, where the lead was used for trade with European countries, and by the late 17th century it was used as a currency, well before the scramble for Africans. Typical background concentrations of lead do not exceed 0.1 μg/m3 in the atmosphere or 100 mg/kg in the soils and 5 μg/L in freshwater and seawater (Harrison, 2012).
Ores of lead:
There are several minerals from which Lead is extracted since many years. The primary ore of Lead is galena or Lead sulphite (PBS). It is naturally unstable, and if exposed for a prolonged time to the atmosphere, it gets oxidized to the other minerals such as cerussite (PbCO3) and anglesite (PbSO4). Its ores are generally found in association with other metals, predominantly Hg which can be mined at the same time – and zinc, which can result in complications during smelting. Gravita is found engaged in the importation of Lead ore worldwide and yields pure Lead and Lead alloys for developing lead acid batteries and in other applications (Harrison, 2012; Fischman, 2016) Lead-Ore Extraction.
Usage of Lead:
Primordial Egyptians stood first to use lead in cosmetics, despite the fact the Egyptians used lead for constructing enamels and for creating adornments. Several cultures in Fertile Crescent recycled it as an inscription thing, for making currency like coins, and for building construction materials. In Ancient Chinese royal court it was once used as a tonic, and as a contraceptive, while civilization of Mesoamericans and Indus Valley used it for creating charms. However, the African both southern and northern peoples used it in wire illustrations (Tian et al., 2014).
As prescribed by Kamenov and Gulson (2014), In Roman Empire it was used for constructing water pipes. Its ease while working and resistance against corrosion ensure its pervasive practise in other applications including pharmaceuticals, and warfare. Renowned writers of their time, such as Cato, Pliny and Columella, acclaimed lead or its coated vessels for the synthesis of food preservatives and sweeteners and adulterating of wine in the wine industry.
Starting back in the 13th century, it was used to produce tainted glass. At the time of Arabian and European civilizations of alchemy, Pb was marked as an impure base metal which can be transformed into pure gold by purifying and balancing out its constituent the separation, purification. Lead is considered as an integral material in parts of the printing press, but its exposure leads poisoning. Weapons were developed at the same time, and lead became the chief material for making bullets despite being more expensive than iron. Pb was considered to be less damaging than iron gun barrels. Because of higher density and better retention against velocity it was found useful for the production of bullets (Kamenov and Gulson, 2014).
Western Europe used them in cosmetics, as whitened faces and was regarded as a sign of modesty. This practice eventually lingered to white wigs and eyeliners. A parallel fashion seemed in Japan in the 18th century with the arrival of the geishas, a practice that continued till the 20th century. In the second half of the 18th century, a great part of lead was used for plumbing and painting—lead paints probably were frequently used. In the middle Ages, Lead has been used for making bullets. It is inexpensive and its less density allows better resistance of velocity (Stokke, Brainerd and Arnemo, 2014). In the case of bullets, lead is often alloyed with tin or antimony that increases its rigidity creating it more operative against hard targets. Lead is widely used in stabilizer in schooner tips. Its mass permits to counterbalance the repairing effect of the wind on the sails; being dense it minimizes water opposition. It is also used in scuba diving weight belts to neutralize the diver’s buoyancy while he is diving (Madry et al., 2015).
According to Stokke, Brainerd and Arnemo (2014), lead is extensively used as a defensive scabbard for subaquatic cables as it provides resistance against corrosion. In the construction industry, its sheets are usually used as building material by architectures while roofing, flashing, cladding, or constructing gutters and gutter joints. It is often mixed with alloys of brass and bronze, to augment its machinability and greasing potentials. Copper alloys with a higher amount of lead are used for the construction of bearings where lead offers lubrication and the copper offers the load-bearing support. Lead sheets in sound studios are employed as a sound dampening layer within the ceilings or walls. Lead with various amount of iron mixed in it is used as a traditional base metal for organ pipes, where they control the tone of each pipe………………………………………………………….continued
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