Specifications of lead metal
Lead ( Plumbum or Lead ) is a soft and heavy metal with an atomic weight of 2/207. Lead has good corrosion resistance and is one of the oldest metals used by humans. Lead has a melting point of 327.5 ° C, a boiling point of 1740 ° C and a volume mass of 11.34 gr / cm3, and if you are familiar with the characteristics of copper metal , you will see that the thermal and electrical conductivity of lead metal is about 0.1 metal. It is copper. Dry lead is an alloy of lead with antimony-calcium with calcium-aluminum and tin. These alloys are usually called hard lead. Familiarity with the specifications and types of alloys of this metal makes it easier for you to buy lead metal .
Soft lead alloys contain a high percentage of lead. Crude lead is soft and has a minimum purity of 99.97% according to the London Metal Exchange (LME = London Metal Exchange) and most refiners achieve a purity of 99.999% during the desalination process. The price of lead ingots in the Iranian market varies depending on its purity.
Lead in Group 14 (IVA) is the periodic table as a weak metal Poor metals and is in period 6. Lead becomes dark gray and opaque when exposed to air, but in the form of healthy, freshly broken surfaces is bluish white and has poor electrical conductivity.
Lead and zinc are always mixed in nature and have common rocks. Lead is a strategic metal. Because most urban and military activities rely on energy stored in lead-acid batteries. The properties of zinc are such that it has many applications in the manufacture of alloys.
Pure refined lead is called soft lead. So far, 130 types of lead ores are known, among which lead sulfur is the most important and economical, and 90% of Iran’s lead production is obtained from this ore. Another important ore is serosite lead (PbCO3) in which the lead grade in this ore is about 77.55%. Lead and zinc deposits are usually associated with important deposits of barite and fluorine and are therefore very important. Because other deposits can be obtained in the exploration stages, in addition, associated minerals can be used in the processing process.
Nearly 70% of the world’s gross lead production comes from mixed lead and zinc ores. So far, about 130 types of lead ores are known, among which lead sulfide or galena is the most important and economical type of lead ores, and 90% of lead production is obtained from it.
Lead is a soft metal with a bluish-gray color, metallic luster, relatively high specific gravity (11.35), atomic number 82, malleable, cutable, with low melting point (327.4 ° C) and high boiling point (1700 degrees Celsius).
Lead metal in nature
Lead metal is a very bright and bluish metal that is less than copper and zinc and is the thirty-first most abundant element in the earth’s crust and makes up only about 0.0013% of the earth’s crust. This is not a very rare case, as it is relatively widespread and easy to extract. Lead metal is typically present in very small amounts in ores such as galena, anglesite and cervicite.
The chemical symbol for lead metal is Pb, which is derived from the Latin word plumbum, meaning “water plant”, which refers to antiquity. When this metal was widely used in the manufacture of water pipes. Although there are 27 lead isotopes, only four are considered stable.
Lead has poor flexibility and, when exposed to air, appears dark gray and opaque, but in the form of healthy, freshly broken surfaces is bluish white and has poor electrical conductivity.
The main minerals are lead
The important minerals of lead in terms of importance and abundance are as follows:
- Pbs gallons : Most zinc sulfide minerals are found with zinc sulfide or Bland (ZnS) minerals and metals such as silver, cadmium, copper, antimony and gold along with gallons.
- PbSo4 parasite : often associated with gallons.
- PbCo3 serosite : often associated with gallons and parasites.
World Lead History
Lead is one of the six metals known and used since the fourth millennium BC. According to archaeologists, the oldest people to use lead were the Egyptians, who used the metal to glaze dishes and extract silver from its silvery minerals. Then the Romans and finally the Iranians, the Chinese, the Hindus, the Russians and the Arabs were among the tribes that knew and used lead from ancient times.
The presence of traces of lead and tools left from that period indicates the significant use of this metal. Due to the malleability of lead, craftsmen were able to melt it well and bring it into various forms needed by the market at that time.
History of lead in Iran
In Iran, lead has been known since the late third millennium BC, and because lead carbonate is easily melted, the exploitation of lead carbonate mines has received more attention. In pre-Islamic times, lead was used as a mortar in construction, dam and bridge construction, as well as for making paint, painting and medicine. After Islam, the exploitation of lead mines was due to the extraction of silver, so that even in some books these mines are called silver mines.
Prior to World War II, lead consumption in Iran was low and lead mines were not exploited much, while after the war, such mines became important and lead was used as an export and currency product.
What are the sources of lead?
So far, 130 types of lead ores have been identified, among which lead sulfur ores (gallons) with 90% production is the most important and economical mineral. This mineral contains 86.6% of pure lead. This mineral crystallizes in the cubic system and is seen as a mass, granular and coarse or scattered.
Its color is dark gray, light gray and has a metallic sheen. The hardness of the gallon is 2.5 and its specific gravity is 7.5 grams per cubic centimeter and there is always some silver in its composition. Other important minerals are lead serosite or lead carbonate with a lead content of 77.55%. This mineral is formed in the form of a mass, 3 grains to dense, 2 stems and filaments (with silky luster). The hardness of serosite is 3 and its specific gravity is 6.5.
Lead is found in nature in the form of sulfides, sulfates, carbonates and lead salts. Lead sulfate is another important mineral, lead, which contains 68.33% lead and is colorless, clear to translucent, and has a nap to diamond polish. Its hardness is 3 and its relative specific gravity is 3.6. Lead is usually found in minerals along with zinc, silver and (mostly) copper and is excreted with these materials.
Approximately 70% of mineral lead is produced from mixed ores of lead and zinc, which typically contain higher amounts of lead than lead. About 20% of lead production is from mixed ores, which contain more lead than zinc, and the remaining 10% of lead production is from responsible minerals.
Lead metal production methods
Because the dissolution of lead compounds in solvents is low, pyrometallurgical method (dry) is used to produce more lead. Basically, lead is extracted in two ways, traditional and new.
A ) The traditional method or the blast furnace method
Currently, more than 75% of the world’s lead is produced this way. This method is becoming obsolete due to high investment volume, more pollution and lower energy efficiency.
Lead production in this method is done in the following three steps:
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Zenter stage and distortion
At this stage, the lead concentrate is heated so that the sulfur compounds are mainly converted to lead oxide and volatiles and unstable compounds are removed from the concentrate.
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Melting and resuscitation stage
At this stage, the purified concentrate with the help of smelting and coking materials enters the blast furnace and is formed by the blowing of oxygen and the heat of reducing gases and causes the conversion of various compounds of lead to pure lead. Lead enters the molten phase and impurities go into the slag with the overhead of the structures.
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Purification stage
The lead grade from the blast furnace is about 97%. In order to increase the grade to 99.9%, at this stage, impurities such as Zn, Cd, Ag, Cu are removed.
B ) New or direct methods
In these methods ( Caldo method or TBRC method, KIVCAT method, QSL method and autocompo method ), unlike the blast furnace method, lead is extracted from the ore in one step and there is no need to separate the concentrate. Similar to the traditional method, the obtained raw lead needs to be refined in order to increase the grade.
What are the stages of lead metal production?
The ore in Iran’s lead metal mines is separated by drilling or blasting, then crushed and placed on the ground. By flotation, lead and other minerals are separated from the rock residue to form an extract by passing ore, water, and special chemicals from a number of reservoirs into which the slurry is always mixed.
Air flows through these tanks, and lead sulfide adheres to the bubbles and rises to the bottom, which can be removed. The foam (which contains approximately 50% lead) is dried and then sintered to 97% lead before refining.
The lead is then cooled in various steps to remove lighter impurities and separate them. The molten lead is refined by further melting by passing air over it and forming a layer of metal pulp containing all the remaining impurities, and a pure lead of 99.9% is obtained.
Solubility of lead metal
Under normal conditions, lead does not react with water, but if kept in close proximity to humid air, its reactivity increases and a thin layer of lead oxide (PbO) forms on its surface. When both oxygen and water are in the environment, lead metal is converted to lead hydroxide.
Lead forms a bond with sulfur in the form of sulfide and with phosphorus in the form of phosphate, which is highly insoluble. Lead compounds are generally soluble in mild water that is slightly acidic. Acids have no effect on lead. The metal itself is often coated with its own solutes and protects the rest of the metal from the effects of acids.
By adding dilute sulfuric acid to lead, it first produces PbSO4, but due to the insolubility of lead sulfate, the interactions stop after a short time. Therefore, lead containers are used in the preparation of sulfuric acid. Hydrochloric acid has a similar effect to sulfuric acid. The best solvent for lead is nitric acid, but lead nitrate is insoluble in concentrated nitric acid. Thus, lead does not dissolve in concentrated nitric acid. Lead nitrate solution is usually used for experiments.
Lead metal producing countries
In 2016, 4 million and 790 thousand tons of mineral lead was produced, which was about 43% of the total production of lead metal in the same year. China, Australia and the United States were the world’s largest producers of lead this year, respectively.
According to the US Geological Survey (USGS), the world’s lead reserves are estimated at 88 million tonnes, of which Australia , with 35 million tonnes, which is equivalent to 40% of the world’s reserves, ranks first in zinc mineral reserves. contract. After Australia, China is in second place with 17 million tons of lead reserves, 19% of the world’s reserves belong to China.
Russia has the third largest mineral reserves in the world with 6,400,000 tons; Its share of the world’s lead reserves is 7%. Peru , with 6,300,000 tons, has a 7% share of the world’s reserves. It ranks fifth in Mexico and holds 6% of its lead reserves. The United States and India are next in line, respectively.
The largest countries producing lead from the mine in 2016 |
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| Row | Country | Output ( in thousand tons ) | Row | Country | Output ( in thousand tons ) |
| 1 | China | 2.400 | 10 | Turkey | 75 |
| 2 | Australia | 500 | 11 | Iran | 41 |
| 3 | America | 335 | 12 | Kazakhstan | 41 |
| 4 | Peru | 310 | 13 | Poland | 40 |
| 5 | Mexico | 250 | 14 | South Africa | 40 |
| 6 | Russia | 225 | 15 | North Korea | 35 |
| 7 | India | 135 | 16 | Ireland | 33 |
| 8 | Bolivia | 80 | 17 | Macedonia | 33 |
| 9 | Sweden | 76 | 18 | Other countries | 170 |
Usage of lead and its compounds
Although lead metal is not used in many previous applications today, this non-corrosive metal is actually very useful in products that retain highly acidic materials. For example, lead is used to make tanks that contain corrosive liquids such as sulfuric acid.
Due to its low density and ability to absorb vibration, lead is an excellent protector against various types of harmful radiation, such as those found in X-ray machines and nuclear reactors. Lead metal is still used to make some bullets and ammunition.
The main issue is the consumption of lead in batteries and most importantly in car batteries. Despite the decrease in previous consumption cases, along with the increase in car production, the production of lead-acid batteries will also increase. Due to the growth of the car market in China and India, the demand for acid batteries has increased slightly.
In addition to car batteries, batteries are used in mobile phone centers, electric cars, electric vans, as well as emergency power supplies for computers and hospitals.
Lead is still used in some chemical compounds and, for example, in wind and rain buildings, to protect power cables and ammunition.
The most important uses of lead metal and its compounds are as follows :
- Lead is added to gasoline as a combination of tetraethyl lead for combustion.
- Lead is used in ammunition and military industries.
- Due to its high density, lead is used in the walls of nuclear reactors and in X-ray chambers and radiographs to absorb harmful rays.
- Lead metal is used in the bed of galvanizing baths.
- Lead, tin and zinc alloy in the soldering industry, lead and tin alloy in the printing industry, lead and silver alloy in the preparation of anodes used in the electrolysis unit of zinc and lead alloys, arsenic and antimony in various industries and finally lead, tin, alloy Copper, antimony, arsenic and cadmium are used as an anti-wear alloy in the manufacture of bearings.
- Lead oxides are used in the paint and matchmaking industries.
Environmental effects of lead
Extraction, production, use and disposal of Pb and its products have caused significant pollution of soil and water. The emission of crude lead gases peaked during the Industrial Revolution and the period of lead gasoline production in the second half of the twentieth century. Pb emissions come from natural sources, industrial production, incineration and recycling, and previously disposed lead. High concentrations of Pb in soils and sediments are stable in industrial and urban areas.
Pb can accumulate in soils, especially those with high organic content, and persist for hundreds to thousands of years. It can potentially compete with other metals inside and on plant surfaces and negatively affect plant growth and survival by inhibiting photosynthesis at sufficient concentrations.
Soil and plant contamination can lead to food chain contamination that affects microorganisms and animals. In animals, the metal is toxic to many organs and damages the nervous, renal, reproductive, and cardiovascular systems after ingestion, inhalation, or dermal absorption.
Absorption of this metal from water and sediments and environmental accumulation in the food chain is a great danger for fish, birds and marine mammals.
If you need buy lead from Iran or get Iran zinc price, contact us.
Translated by Google
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