Points for Attention in the Use of Roller PTF

       Natural attributes and status

Lead is a commonly used non-ferrous metal, and its annual production and sales ranks fourth after aluminum, copper and zinc among non-ferrous metals. The chemical symbol for lead is Pb (Latin Plumbum), and its atomic number is 82, the highest atomic number among all stable chemical elements. The density is 11.34g/cm3, the melting point is 327.5℃, and the boiling point is 1740℃. It has strong resistance to radioactive penetration. Lead is a silver-gray lustrous heavy metal that is easily oxidized in the air to form a layer of lead oxide or basic lead carbonate, which tarnishes the surface of lead and prevents further oxidation. The electrical conductivity of lead is quite low, the corrosion resistance is very high; the quality is soft, the ductility is weak, and the malleability is strong.

Lead in the crust often coexists with zinc and copper to form lead-zinc ore or lead-zinc-copper ore, which generally contains gold, silver, bismuth, cadmium, indium, germanium, tin and other metals in addition to lead, zinc and copper. Therefore, lead ore needs to be pre-processed to obtain a concentrate containing 40-70% lead before smelting.

At present, the world's industrialized lead smelting processes include the former Soviet Union's oxygen flash smelting-electrothermal reduction method (Kivcet), QSL lead smelting, oxygen-enriched top blowing immersion smelting (ISA and Ausmelt lead smelting), Carl Multi-converter lead smelting, blast furnace lead smelting, oxygen bottom blowing lead smelting (SKS), etc.

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

Lead can be recycled without any loss of physical and chemical properties. At present, 90% of the lead that can enter the circulation chain is recycled.

China is the world's largest lead producer and consumer. In 2009, the output of refined lead reached 3.55 million tons, accounting for 41% of the world's total output of 8.67 million tons. The consumption of 8.225 million tons accounted for 40%.

Lead classification and quality standards

Lead ingots are divided into large ingots and small ingots. The small ingots are rectangular trapezoids 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 grabbing slots on both sides. The single weight of small ingots can be: 48kg±3kg, 42kg±2kg, 40kg±2kg, 24kg±1kg; the single weight of large ingots can be: 950 kg±50kg, 500 kg±25kg. According to the national standard GB/T 469-2005, domestic lead ingots are divided into 5 grades according to chemical composition: Pb99.994, Pb99.990, Pb99.985, Pb99.970, Pb99.940.