This is a study on the beginning and the applications of lead. In this study, we will make research on the chemical constituents in lead ores. And we will happen out the beginning of the lead ores and acquire the location for lead sedimentations. This will assist us happen out the procedure of formation of lead ores. Besides we will make researches on the applications of lead in human society including industrial production procedure, commercial productions, and universe production history. Since lead is a sort of non-renewable resources, we will besides make a research on the monetary value of lead. Finally, base on information we obtains from researches, we will eventually do a anticipation of lead resource in the hereafter.
Chemical Components in lead ores
“ Lead is a bright and splintery metal with a really little shadiness of blue in a dry ambiance. “ ( Polyanskiy, N. G. ( 1986 ) ) . Like other metal resources, Lead is chiefly exists in a mixture of different chemical compounds. “ Lead is chiefly found in ore with Zn, Ag and Cu. The chief leadA mineralA isA galenaA ( PbS ) , which contains 86.6 % lead by weight. “ ( Holleman, Arnold F. ; Wiberg, Egon ; Wiberg, Nils ; ( 1985 ) . ) This information shows that, take normally exists in “ +2 ” oxidization province in lead ores. And the assortments of lead mineral shows that lead is a sort of reactive metal which can respond easy with other oxidising agent such as S ( S ) . This could turn out further that pure lead metal barely exists in the nature since the chief lead mineral is galena, which is a sulphide of lead ( PbS ) .
Beginning of Lead ores
As I mentioned in old portion, galena is the chief ore of lead. Galena crystallizes in three-dimensional crystal system. Since galena exists in crystal signifier, I believe that stones contain galena should be metamorphous stones. Besides, lead is comparatively reactive as I mentioned in the old portion. Furthermore, the runing point of lead is comparatively low ( 600.61A K, 327.46A A°C ) comparison to other metal like Fe. It is possible that galena will be in hydrothermal environment. The information recorded in Handbook of Mineralogy supports my point: “ ( Galena occurs ) in many dii¬ˆerent types of environments. In hydrothermal venas, formed under a broad scope of temperatures ; in contact metamorphous sedimentations, in pegmatites, seldom ; limestone and dolostone are common host stones. ” ( Galena. Handbook of Mineralogy 2001-2005 Mineral Data Publishing, version 1. )
Besides, galena is associated with other mineral such as vitreous silica and silver mineral. Since galena can be form in different procedures such as metamorphism or hydrothermal synthesis. ( Galena. Handbook of Mineralogy 2001-2005 Mineral Data Publishing, version 1. ) And common demands between these 2 procedures are: high temperature and high force per unit area. Metamorphism normally occurs under heat, force per unit area, emphasis and fluid. And hydrothermal synthesis occurs under high force per unit area and hot H2O ( vapor ) . Since both procedures can organize galena, it is possible to believe that the galena crystals can be formed under high temperature and high force per unit area.
Geology of Lead Mineral
As I mentioned in old portion, due to different formation procedure, galena will tie in with different mineral and sedimentation otherwise in different country of the universe. By and large, there are 2 types of lead ore sedimentations: Mississippi Valley type ores sedimentation ( Carbonate hosted lead Zn ores sedimentation ) ( MVT sedimentation ) and clastic-dominated sediment-hosted lead Zn sedimentations ( SEDEX sedimentation ) .
Here is the map for 2 types of deposits2000px-MV-Type_and_clastic_sediment-hosted_lead-zinc_deposits.svg.png
( U.S Geology Survey Open -File Report 2009-1297 Compilation of Mineral Resource Data for Mississippi Valley-Type and Clastic-Dominated Sediment-Hosted Lead-Zinc Deposits By Ryan D. Taylor, David L. Leach, Dwight C. Bradley, and Sergei A. Pisarevsky. )
From the map, we can detect that the MVT deposition is chiefly distributed in Mississippi Valley and nearby country in USA and Canada and besides Western Europe.
And the SEDEX deposition is chiefly distributed in these 4 states: China, India, Canada and Australia.
“ MVT sedimentation occurs as replacing and unfastened infinite fillings developed in favorable beds or skylines within thick sequences of shallow H2O dolomite or limestone. The ore is deposited at temperatures of 70-150A°C from metal-rich seawaters migrating through the basin. The venue of ore deposition is often proximal to major breaks and/or reef facies. Dolomite, calcite, vitreous silica and chert are common gangue minerals, and heavy spar and fluorspar may besides be present in important measures. The chief ore minerals are sphalerite, galena, fool’s gold and copper pyrites, with Fe sulfides much less abundant than in stratiform sedimentations. Cherished metal values are normally low. ” As Tony Christie and Bob Brathwaite noted in Mineral Commodity Report 6 -Lead and Zinc. ( Mineral Commodity Report 6 -Lead and Zinc by Tony Christie and Bob Brathwaite Institute of Geological and Nuclear Sciences Ltd November 2011. ) This states that MVT deposition is formed under low temperature in hydrothermal environment with metal-rich halide solution.
Polishing Process of Lead minerals
Before the refinement procedure, I have to observe that for MVT lead Zn deposition, ore classs normally range from 3 % to 10 % for lead and Zn. Exploiting ores with less than 3 % lead is non economically efficient.
For the refinement procedure, ores will foremost be broken into little pieces and concentrated by froth floatation typically to 70 % or more. ( Charles A. Sutherland noted in “ Lead ” in Ullmann ‘s Encyclopedia of Industrial Chemistry, 2005 ) Since galena ores contain Sulfur. Ores will be roasted to bring forth primary lead, in this procedure, Sulfur dioxide ( SO2 ) will be take and a mixture of silicates and other unwanted metal or unreduced lead will be obtained as waste. ( Charles A. Sutherland noted in “ Lead ” in Ullmann ‘s Encyclopedia of Industrial Chemistry, 2005 )
“ After that, lead oxide will be reduced to metal by decrease reaction in coke-fired blast furnace. In this procedure, since runing point of lead is so low, the waste will remains as solid stated and float to the top of metallic lead and produce extra
bed. ” ( Charles A. Sutherland noted in “ Lead ” in Ullmann ‘s Encyclopedia of Industrial Chemistry, 2005 )
After this procedure, all the non-metal waste such as silicates will be removed. And the staying will be a mixture of metals such as Zn, gold, Ag and Cu. ( “ Primary Extraction of Lead Technical Notes ” . LDA International. Archived fromA the originalA on 22 March 2007. Retrieved 7 April 2007 ) .
For the metallic contaminations which are more reactive than lead, ( i.e Cu ) they will be removed by handling the mixture in a “ reverberatory furnace with air, steam and S. ” ( “ Primary Extraction of Lead Technical Notes ” . LDA International. Archived fromA the originalA on 22 March 2007. Retrieved 7 April 2007 ) . This will oxidise the more reactive contaminations so take them by drossing.
For metals which are less reactive than lead ( ie. Silver, gold and Bi ) , they can be removed by following procedure.
For Ag and gold, they can be removed by Parkes procedure for other economical intent. The nature of Parkes procedure is to do usage of different solubility of Ag and gold in liquid lead and liquid Zn. ( Pauling, LinusA General ChemistryA W.H.Freeman 1947 erectile dysfunction ) By add-on of liquid Zn to liquid lead, gold and Ag will be extracted into liquid Zn. Cool down the mixture easy. Since Zn has a higher thaw point and lower denseness, metal Zn with gold and Ag will drift at the top of liquid lead which can be easy removed. ( Percy, John ( 1870 ) .A The metallurgy of lead: Including desilverisartion and cupellation. pp.A 148 )
After this procedure, the staying metallic contamination will be Bi, which can be removed by Betterton-Kroll procedure. ( Samans, Carl H.A Engineering Metallic elements and their Alloys, 1949 MacMillan ) The nature of this procedure is adding metal Ca and Mg to liquid lead with Bi which can organize a Bi compound with higher thaw point and lower denseness which can be removed easy by chilling the mixture. ( Samans, Carl H.A Engineering Metallic elements and their Alloys, 1949 MacMillan ) This is similar to Parkes procedure which are doing usage of the physically belongings of lead to take the contamination.
Finally, really pure lead can be obtained through electrolyte the primary lead obtain after the old measure. The procedure uses anodes of impure lead and cathodes of pure lead in an electrolyte of silica fluoride. “ ( “ Primary Extraction of Lead Technical Notes ” . LDA International. Archived fromA the originalA on 22 March 2007. Retrieved 7 April 2007 ) .
Harmonizing to these information of polishing lead mineral, I could approximately reason that polishing lead mineral is a procedure which taking all the unwanted constituents in lead ores through a series of chemical oxidation-reduction ( reduction-oxidation ) reactions.
Commercial Use of Lead
Since Lead is distributed everyplace around the universe and it is so easy for human to pull out from the nature. It has been widely used for 1000s of old ages. From ancient Roman lead pipes ( Hong, Sungmin ; Candelone, Jean-Pierre ; Patterson, Clair Cameron ; Boutron, Claude F. ( 1994 ) ) to ancient Tang Dynasty sancai ceramic cup ( Leonard, Alvin R. ; Lynch, Glenn ( 1958 ) ) . Lead is easy found in human history.
Nowadays, since lead is extremely toxicant ( United States Environmental Protection Agency, April 2012 ) , the uses of lead are chiefly in industrial country. For illustration, since lead has vary oxidization provinces ( +2 and +4 ) , “ lead can be used as lead-acid battery extensively as a auto battery. ” ( Environmental Defense, Ecology Center, Clean Car Campaign ( July 2003 ) )
Besides, since denseness of lead is high and lead resists from corrosion. Lead can be used for ballast keel for sailing boats. ( Lead Ballast. 2007. ) Lead does non merely have opposition from corrosion, but besides have opposition from radiation, which means lead bricks can be made as radiation shield in atomic reactor or in X-ray room in infirmaries. ( Bethesda. 2004. ) Furthermore, lead is a metal with comparatively low runing point. “ Therefore liquefied lead can be used as a coolant in atomic reactors. ” ( TuA?ek, Kamil ; Carlsson, Johan ; Wider, Hartmut ( 2006 ) )
World Production History Of Lead
In the history, the universe production of lead alterations in response to certain political or economical events.
( Here is the graph of World Production of lead in Book Air quality standards for lead )
From the graph, we can detect that the increase of lead production follows certain historical events ( Internet Explorer. industrial revolution ) .
( Here is a more detail graph from Hong, Sungmin ; Candelone, Jean-Pierre ; Patterson, Clair Cameron ; Boutron, Claude F. ( 1994 ) demoing that how production of lead addition in footings of a century. )
Besides we can impute the elephantine increase of lead production in recent old ages to innovation of electricity. With assistance of electricity, human can easy polish metallic lead through electrolysis.
( Here is a graph produced by myself by utilizing informations from MCX and Mineral Commodity Summaries 2012 ( describe name ) on USGS ( U.S Geology Survey ) to demo the universe production of refined lead in recent old ages. )
These graphs show that the tendency of lead production is by and large increasing through human history.
Commodity monetary value of Lead in the past few old ages
As the demand of lead additions, the trade good monetary value of lead will besides increase. Since lead is besides a sort of trade good in the market, the monetary value of lead will besides be affected by human economical activities.
Here is a graph demoing the tendency of the monetary value of trade good lead in London Metal Exchange ( LME ) in the past 20 old ages. ( Data beginning: U.S.G.S and India Bureau of Mines )
USD per ton
This graph shows that the monetary value of trade good has a by and large increasing tendency but will be affected by certain human activities. For illustration, drops between 1997-1998 and 2007-2009 are due to 2 fiscal crises.
Future of Lead
Lead is limited. As demand additions in the hereafter, the monetary values will besides increases. High monetary value will coerce human to use lead more expeditiously. And the way of using lead will still be energy beginnings.
Base on researches I have made, I can hold a more systematic position on lead resource and I can understand the utilizing procedure of lead. Finally, I conclude all the information I got from the researches and I notice the importance of lead to human society.
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