The history of lead
Lead is one of the earliest metals used by humans. Humans have recognized lead 7000 years ago, and smelted lead from ore in 3000 BC. In the British Museum there is a lead statue of 3000 BC found in the Abydos Mosque in Egypt. Among the materials obtained from the excavation of historical sites in Ur city and other cities in Iraq, there are records of clay tablets in the form of written characters used by the ancient Persians. These records indicate that large amounts of iron, copper, silver, and lead were extracted from ore in 2350 BC. During the rule of the Babylonian emperor Hammurabi from 1792 BC to 1750 BC, mass production of lead had already begun.
The bronze ware of the Erlitou culture with the animal face design also found that lead was added as an alloy element, and together with tin throughout the Bronze Age, it constituted the most important alloy element in ancient Chinese bronzes. Lead-made wine vessels such as 卣, Jue, Gou and Ge were also found in the tombs of the Yin Dynasty in my country.
In Europe, from the Greek and Roman times until the 16th century, people did not start to use graphite to make pencils, and they clamped lead rods in wooden sticks to write on paper. This is where the term pencil came from. In the Middle Ages, because lead had good corrosion resistance, lead sheets began to be used to make roofs for churches and houses in the United States, a country rich in lead. The original lead chamber method used to manufacture sulfuric acid also took advantage of the corrosion resistance of lead.
Due to the environmental pollution caused by lead, the application of lead began to decline suddenly in the 1980s. Today's gasoline, fuel, solder, and water pipes are generally free of lead.
refining
Pure lead is rare in nature. Today lead is mainly refined with metals such as zinc, silver and copper. The main lead mineral is galena (PbS), which contains 86.6% of lead. Other common lead-containing minerals are white lead (PbCO3) and lead alum (PbSO4). The total annual output of lead is about 8 million metric tons, about half of which is recovered from waste. As of 2008, the largest lead producing regions in the world were Australia, China, the United States, Peru, Canada, Mexico, Sweden, Morocco, South Africa and North Korea.
Lead ore is generally mined by drilling or blasting. Lead ore is ground after mining and then mixed with water and other chemicals (such as the surfactant sodium xanthate). Bubbles will rise in these mixed liquid containers, and lead-containing minerals will form a layer of foam as the bubbles rise to the surface, and this layer of foam can be collected. This process can be carried out many times, and finally 50% lead is obtained. These foams can get 97% lead after they are collected and dried and melted. Then people slowly cool the molten liquid, the impurities are relatively light and rise to the surface to be removed. The remaining lead melts again. People send cold air into the melt, and the impurities float up and remove the energy to obtain lead with a purity of 99.9%.
development of lead industry
In recent years, China's industrialization and urbanization process has actively promoted lead consumption, which has enabled my country's lead and zinc industry to develop rapidly, and gradually occupy an important position in the global lead and zinc industry chain. Since 2003, China has surpassed the United States to become the world's largest refined lead producer, and has maintained its absolute advantage ever since. However, my country's lead and zinc smelting industry also has some problems in the development process, such as prominent structural contradictions, low level of resource protection, and lack of voice in product prices. Therefore, it is urgent to increase industry reforms to realize the sustainable development of my country's lead and zinc smelting industry.
About puda:
PUDA is specialized in automatic quantitative packaging machine for powder, granule, particle, pelleted, sliced, flaked, bulk materials.
Qinhuangdao Puda Electronic Co., Ltd , which provides automatic intelligent packaging solutions, is an automatic equipment manufacturing enterprise integrating R&D, manufacturing and sales of equipment. With a high-tech team engaged in the research and development and manufacturing of automation equipment, adhering to the concept of knowledgeable and dense, sincere service, from design and development, production and manufacturing to after-sales service, to professional technology, first-class quality service in all industries; Up to now, the strength and product quality of the company have been highly recognized by the industry. Welcome friends from all walks of life to visit, guidance and business negotiations.
