Natural attributes and status
Lead is a common non-ferrous metal and its annual sales volume ranks fourth in non-ferrous metals after aluminum, copper and zinc. The chemical symbol of lead is Pb (Latin Plumbum) with an atomic number of 82, which is the highest atomic number among all stable chemical elements. Density 11.34g/cm3, melting point 327.5°C, boiling point 1740°C. Has a strong resistance to radioactive penetration. Lead is a kind of silver-grey and shiny heavy metal that is easily oxidized in the air to form a layer of lead oxide or basic lead carbonate, which delustens the lead surface and prevents further oxidation. Lead has very low electrical conductivity, high corrosion resistance, and is soft, ductile, and malleable.
Lead in the earth's crust is often symbiotic with zinc and copper and constitutes lead-zinc mines or lead-zinc-copper mines. In addition to lead, zinc, and copper, they generally contain metals such as gold, silver, antimony, cadmium, indium, bismuth, and tin. Therefore, lead ore needs to be refined by pre-concentration to obtain 40-70% of lead concentrate for smelting.
The world's industrialized lead smelting processes include the former Soviet Union's oxygen flash smelting-electrothermal reduction (Kivcet), QSL lead smelting, oxygen-enriched top-blown submerged smelting (ISA and Ausmelt smelting), and Karl Multi-converter smelting lead, blast furnace smelting lead, oxygen bottom blowing lead (SKS) and so on.
The consumption of lead concentrates on lead-acid batteries, cable sheathing, lead foil and extrusion products, lead alloys, pigments and other compounds, gasoline additives, ammunition, and other aspects. Lead consumption in lead-acid batteries accounts for total consumption. More than 75% of the amount.
Lead can be completely recovered without any loss of physical and chemical properties, and 90% of the lead currently available in the recycling chain is recycled.
China is the world’s largest producer and consumer of lead. In 2009, the output of refined lead reached 3.55 million tons, accounting for 41% of the world’s total production of 8.67 million tons; in 2009, China’s lead consumption was 3.33 million tons, in total It accounts for 40% of the total consumption of 8.225 million tons.
Lead classification and quality standards
Lead ingots are divided into large ingots and small ingots. The small ingots are rectangular trapezoids. Bundles are recessed at the bottom and protruding ears are provided at both ends. Large ingots are trapezoidal, with T-shaped bumps on the bottom and grabbing grooves on both sides. The unit weight of small ingots can be: 48kg±3kg, 42kg±2kg, 40kg±2kg, 24kg±1kg; the unit weight of big ingot can be: 950kg±50kg, 500kg±25kg. According to the national standard GB/T 469-2005, domestic lead ingots are divided into five grades based on chemical composition: Pb99.994, Pb99.990, Pb99.985, Pb99.970, Pb99.940.