Lead, one of the non-ferrous metals, has the chemical symbol Pb. The melting point is 327.50 degrees Celsius, which is low and easy to be extracted from the ore. the content of lead in the earth's crust is 0.0016%, and the main ore is galena. By 3000 BC, humans had melted lead from ore.
The texture of lead is so soft that it has been used to write. Lead is very heavy (the density of lead is more than 4.5 grams per cubic centimeter, and the mass is greater than that of metals such as copper at the same volume), and the warheads of subprojectiles are often filled with lead to increase weight and reduce the impact of the wind. Lead is easy to oxidize, from silver to gray-black lead oxide, the formation of this layer of lead oxide film to prevent further oxidation of internal lead, so lead is not easy to be corroded, has been often used to build roofs and pipes, and so on.
Lead is toxic and can not be degraded. it remains toxic for a long time after it is discharged into the environment. once it enters the human body, it will cause great harm to the human body.
The history of lead use in humans is like a history of poisoning, from 50 years of abdominal cramps caused by the use of lead containers by Spaniards in 1730 to lead poisoning by lead roofs and pipes in the Netherlands. From wine lead poisoning in Britain to leaded gasoline in the United States. As a result, the use of lead has declined significantly since the mid-1980s.
At present, the world lead resources are mainly distributed in Australia, China, Peru, the United States and other countries.
According to the US Geological Survey, the global lead reserves are about 88 million tons, of which China ranks second, accounting for 19% of the world's total reserves, after Australia.
The lead reserves in China are mainly distributed in Baiyinoer, Inner Mongolia, Lanping Jinding, Yunnan, Fankou, Guangdong, Xinjiang and Hotan, among which Inner Mongolia and Yunnan account for about 52% of the total lead reserves in China.
In 2016, a super-large lead-zinc deposit was discovered in the Huohuoyun area of Hotan area, Xinjiang, which is the largest lead-zinc deposit with the largest resource reserves in China at present.
Refined lead is mainly distributed in China, the United States, Germany, Canada and other places, of which China is the largest producer of refined lead, accounting for 42%. Since 2010, China's lead production has accounted for more than 40% of the global lead production for many years. 2015 was the only year where lead accounted for less than 40 per cent, mainly because lead prices were at recent lows and losses led to partial production cuts. In addition, the domestic environmental problems also led to the closure of many small and medium-sized lead smelters.
At present, the famous lead smelters and regenerated lead smelting enterprises in China mainly have the following:
Jiangsu Xinchunxing Renewable Resources Co., Ltd.
Anhui Huaxin lead Industry Group Co., Ltd.
Henan Yuguang gold and lead co., Ltd.
Anhui Huapin Renewable Resources Technology Co., Ltd.
Industrial chain of lead: regenerated lead accounts for half of the country
One of the great differences between the lead industry chain and the copper, aluminum, zinc and other industrial chains is that the proportion of regenerated lead in the whole industrial chain is very high. According to the data of the past two years, China's recycled lead accounts for 33% of domestic lead production, and the global share is as high as 56%. The proportion of copper, aluminum and zinc is less than 20%.
The analysis of lead industry chain can not help but involve the regenerated lead, which occupies half of the rivers and mountains.
Because of the factor of regenerating lead, the whole lead industry chain can be divided into two parts. One is the primary chain, that is, "lead mining-mineral processing-smelting-application", the other is the regeneration chain, that is, "waste lead recovery-smelting-application".
The primary chain is the lead concentrate obtained by mining and separation of lead ore, and then the primary lead is obtained by smelting. Lead ore dressing generally produces lead concentrate with lead content of 40% ≤ 70% through crushing, ball milling, foam flotation and other steps. Lead concentrate is usually smelted by fire (wet process is still in the research stage).
Sintering, blast furnace smelting and oxygen bottom blast reduction lead smelting are two common lead smelting methods.
The former is a traditional secondary lead smelting process, which is divided into two stages in sintering machine and blast furnace. The process is mature and low cost, but the energy consumption is high and the sulfur recovery rate is low, which is easy to cause pollution. At present, it has been phased out. The oxygen bottom blowing reduction lead smelting method improves the secondary smelting to the primary smelting. This not only reduces the energy consumption, but also improves the recovery rate of sulfur, avoids dust pollution, and this process is suitable for a wide range of direct treatment of various grades of lead concentrate, but also can deal with a variety of lead-containing materials.
The first step in the recycled lead chain is to recycle and then use mechanized automatic crushing to disassemble the waste. After disassembly, the lead plate, lead paste, waste acid liquid, plastic and so on are recycled and treated for smelting, and the regenerated lead is obtained. The downstream of the lead industry chain is mainly the processing of lead alloy and lead oxide into a variety of lead products, such as lead bomb, cable sheath, lead plate lead pipe and so on, in which lead-acid batteries are the main products, accounting for about 80%.
Waste lead mainly comes from battery plates, cable armor, pipes, lead bullets and lead plates. As long as the waste lead is collected and sent to the recycled lead factory for remelting and resmelting, refined lead, soft lead and various lead-based alloys can be produced.
Lead recovered from waste batteries and cable foreskin contains a small amount of antimony and other metals, and this recycled lead is generally still resold to battery manufacturers. Most of the regenerated lead containing tin is reused to make electrodes, bearing alloys and other lead-tin alloys. Lead in gasoline and dyes can not be recovered, which is the main factor of environmental pollution caused by lead. Lead in foil, electrode, heat treatment and electroplating is currently difficult to recover.
According to the development trend, the proportion of "waste lead recovery-smelting-application" in the whole industrial chain will be higher and higher in the future.
Downstream application: battery is the largest, lithium battery impact is approaching
Although lead is widely used downstream, lead-acid batteries account for 80% of lead consumption in China and the world. It can be said that the consumption prospect of lead-acid battery basically determines the future consumption prospect of lead.
According to the use of lead-acid battery in our country, 41% is used in electric vehicle, 24% is used as automobile (start-up) power supply, and 10% is used as emergency UPS for communication. As the power supply of electric vehicles is mainly used for electric bicycles and electric tricycles, the lead consumption of these two pieces accounts for 30% and 11% of the total consumption, respectively.
Comparative analysis of lead-acid batteries and lithium batteries:
It can be seen that the weight of lithium battery is light, the volume is small, and the service life is longer. These are undoubtedly additions to lithium batteries.
At present, the disadvantage of lithium battery is that the supporting facilities are immature, the technical maturity is general, and the cost is high. However, from the perspective of development, lithium battery technology is making rapid progress, the matching is also constantly improving, and the cost is also falling rapidly. And as far as matching is concerned, the requirements of electric bicycles and tricycles are lower and easier to replace.
However, because the high current discharge performance of lead-acid battery is better than that of lithium battery, it will be difficult to be replaced by lithium battery as the starting power supply of traditional automobile.
Although lead-acid batteries may be replaced by lithium batteries in electric vehicles in the long run, the speed of substitution still depends on the technical maturity of lithium batteries, the rate of decline in costs, and the growth rate of new energy vehicles.
If the future rapid growth of new energy vehicles, lithium battery production is difficult to meet the demand for new energy vehicles, the impact on lead-acid batteries mainly used in electric bicycles is small. If development is slow and lithium batteries are oversupplied, lead-acid batteries may be hit quickly.
However, as far as the current situation is concerned, the impact of lithium batteries on lead-acid batteries has not yet emerged.
In 2015 and 2016, the production of lead-acid batteries in China decreased for two consecutive years, mainly affected by environmental protection policies, that is, environmental protection policies not only affected the production of lead, but also affected the production of lead-acid batteries.