See also: Lead (homonymy), Pb

The lead is a chemical element of the family of the Cristallogène S, symbol Pb and Atomic number 82.

p lum' b' um (lat.) = plomb
bhlei (indogermanic) = to gleam, light

History

The man has used lead for more than 7000 years because of his great diffusion, his facility of extraction, his great malleability and his low point melting. He was used at the time of the Bronze Age with the Antimoine and the Arsenic. Lead is also mentioned in the Exode.

Very easy to melt and format, it was in particular used for plumbing in the Antiquité. One still finds lead pipes carrying the seal of Roman Emperors. Toxicities of some compounds to lead (in particular products of make-up) was however known them.

At the time of the the Middle Ages, the Alchimiste S believed that lead was the oldest Métal and associated it with the Planet Saturn.

At the 20th century, paintings with the pigments containing lead were prohibited for medical reasons. In the majority of the developed countries, the uses of lead were strongly regulated, even prohibited (lead was interdict for the pipes in Switzerland since 1914, but more tardily in many other countries)

Extraction

Lead is a natural product of the disintegration of the Uranium. Native lead is rare, one currently extracts it from ore associated with the Zinc (the Blende), with the money and (most abundantly) with the copper. The mineral independent source is the Galène (PbS) which contains 86.6% in weight of them. Other common varieties are the Cérusite (PbCO3) and Anglésite (PbSO4). Today recycling makes it possible to recover a great part of it. The majority of the ores contain less than lead 10%. The ores which contain less than lead 3% cannot be exploited economically. The Minerai extracts from the ground is concentrated by gravimetry and floatation, then directed towards an iron-foundry (foundry).

The largest layers are with the the United States, in Australia, CEI and with the Canada. In Europe, the Sweden and the Poland have the majority of the layers.

Metallurgy

Starting from sulfides

At the foundry, the ore is first of all roasted to oxidize sulfide and to obtain lead oxide; the Soufre is eliminated in the form of gas dioxide SO {{ind|2}}, transformed and developed into Acid sulphuric. The roasted ore is then introduced, with coke, in a furnace at the base of which one air blast. The reaction of the Oxygène of the air with coke gives Carbon monoxide CO, which reduces lead oxide.

At the base of the furnace run out on the one hand liquid lead, on the other hand a slag which is generally granulated with water before being put in discharge.

The lead collected at this stage is called lead argentiferous; it contains a certain number of impurities (Cuivre, money, Bismuth, Antimoine, Arsenic, etc) which it is necessary to eliminate. This refining of lead, still liquid, is done in tanks, by cooling and addition of various reagents (sulfur, oxygen, zinc to capture the money, etc).

Refining

Refined lead is called soft lead; it is run and solidified in ingot moulds before being dispatched in the consumer or in warehouses of storage. Before final casting, elements can be added in well defined proportions to work out Alliage S (Calcium, Antimoine, etc).

In certain foundries, one uses beside the mining concentrates, of the raw materials resulting from the breaking of the batteries, or the by-products of other industrial processes (lead sulfate for example).

Use

Lead in the form of metal was employed since antiquity because of its large Malléabilité and Ductilité and of low sound melting point, in particular for the realization of conduits of Drinking water (see Plomberie), of crockery, plates of Toiture and gutters. Lead is also used in the Plomberie of art, halfway between the roof and the Sculpture.

In Alloy with the tin and the Antimoine it was used for the manufacture of the characters of Imprimerie. It is called then typographical Plomb.

One of the factors of Toxicité of the ammunition was the lead massively used for a long time for the manufacture of ammunition of war or hunting (Grenaille). With the arsenic and the antimony which are associated to him, it contributes to the Pollution induced by the ammunition.

More recently, lead was introduced into the composition of certain additives (anti-knock) for the Carburant S cars, for example the tetraethyl Plomb.

Lead (in metal plates or in glass) is used as protection to attenuate the rays γ, the X-rays.

Many historical applications of lead were proscribed now because of its toxicity when it is absorbed by the living organisms.

The electric fencers (batteries) became the principal use of lead.

In certain countries (the United Kingdom for example), lead plates are still used in Toiture (whereas in France one uses the Zinc).

In 2004, the lead-acid batteries, intended for the car or industry, account for 72% of the lead consumption (53% car, 19% industry). The pigments and others chemical compounds account for 12% of consumption. The other applications (alloys for weldings, pipes and sheets, ammunition,…) 16%.

The lead addition to Glass form the crystal and increases its glare.

Toxicity

Many the historical uses of lead or its compounds from now on are proscribed because of the Toxicité of lead for the Nervous system (Saturnisme in particular).

A risk exists since the lead or some of its compounds can be inhaled (in the form of vapor or of dust) or introduced, and assimilated by the organization.

To fix some orders of magnitude:

  • with regard to drinking water, the standard in France was of 50 micrograms per liter until December 2003, it passed to 25 micrograms by liter and it is envisaged to make it pass to 10 micrograms by liter in December 2013. In Canada, it is of 10 micrograms per liter since 2001;
  • with regard to the grounds, lead is naturally present (it is what is called the natural bottom pedogeochimic) at height of a few tens of Mg per kg of ground; for example a synthesis of the existing data on the state of the grounds in France (Baize, 1994,1997), watch that the lead contents of 11.150 samples, taken on the surface of the agricultural zones (before mud spreading of purification plant), are relatively dispersed with an average of the contents of 30,3 mg/kg for a median of 25,60 mg/kg. In a public report/ratio of synthesis of BRGM, one finds figures of 10 has to 30 mg/kg for not polluted grounds.

See also: Lead (occupational disease)

Some economic situation

Price of lead

Lead is a metal whose selling price is very cyclic; it is with dimensions in US dollars, in particular with the Stock Exchange of Metals of London. Over the ten last years, the courses evolved/moved enters per ton and ton.

Because of its toxicity, prohibitions of use of lead multiply in the world, which should cause a drop in its price.
Mais paradoxically, it is the metal of which the price the most increased in 2007, vis-a-vis the Chinese demand for batteries according to the ones, vis-a-vis a market which was closed again and which is controlled by some great groups according to the others; repurchases and/or factory shutdown (Closing of Metaleurop North in France for example), factories in difficulties due to pollution and problems medical (Ex: Borough-Faithful), closing in Australia in 2007 of the mine Magellan (3% of the worldwide production, larger mine of the world), followed by an explosion in a refinery (Doe Run) of Missouri which still made climb the prices. In 6 months the price of lead doubled, it was multiplied by seven in four years, reaching a record in October 2007 (, against in 2003). June 26th, 2007 its price exceeded that of the Aluminum before exceeding that of the Zinc.

World demand

It climbed of 2% per annum until 2004 (to 80% to manufacture batteries). It would be into 2007 of 20% per annum approximately.

Semi-2007 world stock fell to 30.000 tonnes." That is to say two days of consumption”. The Employers' federation of lead sees a positive virtue with this rise: it should encourage a better recycling of the batteries (of 130 euros the ton, their price leaped with 350 euros in one year)”.

} |- |Europe || : 2011 |- |Africa || 131 |- |Oceania || 40 |}

Figures of 2003, in thousands of tons of metal contained in the ores and concentrates

Metal lead is produced in factories called foundries (see above Métallurgie chapter), whose raw materials come either from mines (concentrated mining) or of recycling (in particular the recycling of the worn batteries). On the 6,8 million production, approximately 3 million comes from mining concentrates and 3,8 million from recycling. Recycling is thus now the first source of lead.

Symbolic system

  • the Noces of lead symbolize the 14  years of Marriage in the French folklore.
  • lead is the 5th level in the progression of the Sarbacane Sportive.
  • lead symbolizes heaviness.

See too

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