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.
Spade bits are used for rough boring in wood. They tend to cause splintering when they emerge from the workpiece. Woodworkers avoid splintering by finishing the hole from the opposite side of the work. Spade bits are flat, with a centering point and two cutters. The cutters are often equipped with spurs in an attempt to ensure a cleaner hole. With their small shank diameters relative to their boring diameters, spade bit shanks often have flats forged or ground into them to prevent slipping in drill chucks.
Some bits are equipped with long shanks and have a small hole drilled through the flat part, allowing them to be used much like a bell-hanger bit. Intended for high speed use, they are used with electric hand drills. Spade bits are also sometimes referred to as "paddle bits".
Spade drill bits are ordinarily available in diameters from 6 to 36 mm, or ¼ to 1½ inches.
Wood Spade Drill Bit,Fat Drill Bit,Paddle Drill Bit,Wood Drill Bit
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