The natural attributes and classification standards of lead

　　Natural attributes and status

　　Lead is a common non-ferrous metal. Its annual production and sales of non-ferrous metals rank fourth after aluminum, copper and zinc. The chemical symbol of lead is lead (Latin Plumbum), and its atomic number is 82, which is the highest of all stable chemical elements. The density is 11.34g/cm3, the melting point is 327.5°C, and the boiling point is 1740°C. It has strong resistance to radioactive penetration. Lead is a silver-gray glossy heavy metal, which is easily oxidized in the air to form a layer of lead oxide or alkaline lead carbonate, which makes the lead surface lose its luster and prevents further oxidation. Lead has the advantages of low conductivity, high corrosion resistance, softness, weak ductility and strong ductility.

　　 Lead in the earth's crust is usually related to zinc and copper, forming lead-zinc ore or lead-zinc-copper ore. In addition to lead, zinc, and copper, it also generally contains metals such as gold, silver, bismuth, cadmium, indium, germanium, and tin. Therefore, lead ore needs to undergo pretreatment to obtain 40% lead concentrate before smelting.

　　 The current industrialized lead smelting processes in the world include the former Soviet Union’s oxygen flash smelting-electrothermal reduction method (Kivcet, QSL lead smelting, oxygen-enriched top blowing Leaching method (ISA and Ausmelt lead smelting), Kaldor converter lead smelting method, blast furnace lead smelting method, oxygen bottom blowing lead method (SKS), etc..

　　Lead consumption is concentrated in Lead-acid batteries, cable jackets, lead foils and extruded products, lead alloys, pigments and other compounds, gasoline additives, ammunition, etc. The lead consumption of lead-acid batteries accounts for more than 75% of the total consumption.

　　Lead can be completely recycled without losing any physical and chemical properties. At present, 90% of the lead in the recycling chain is recycled.

　　 China is The world’s largest lead producer and consumer, produced 3.55 million tons of refined lead in 2009, accounting for 41% of the world’s total output of 8.67 million tons. In 2009, China’s lead consumption was 3.33 million tons, accounting for 8.225 million tons of total consumption in the world. 40%.

　　Lead classification and quality standards

　　 Lead ingots are divided into large ingots and small ingots, and small ingots are long Square trapezoid, with bundling grooves at the bottom and protruding ears at both ends. The large ingot is trapezoidal, with T-shaped bumps at the bottom, and hanging grooves on both sides. The unit weight of the small ingot can be: 48kg±3kg, 42kg±2kg , 40kg±2kg, 24kg±1kg; single weight of large ingots can be: 950kg±50kg, 500kg±25kg. According to the national standard GB/T469-2005, domestic lead ingots are divided into 5 grades according to chemical composition: Pb99.994, Pb99. 990, Pb99.985, Pb99.970, Pb99.940. Contact: 1803832979