Smelting and classification of lead
01. Lead smelting
The main raw materials for lead smelting are lead sulfide concentrate and a small amount of block ore. There are two methods for smelting lead: pyrometallurgy and wet metallurgy. Currently, pyrometallurgy is the main method in the world, and wet metallurgy of lead is still in the experimental research stage. The pyrometallurgical lead smelting process basically adopts the sintering roasting blast furnace smelting process, accounting for 85-90% of the total lead production; Next is the reaction melting method, which can be equipped with chamber furnaces, short kilns, electric furnaces, or vortex furnaces; Precipitation melting is rarely used. The refining of lead mainly adopts fire refining, followed by electrolytic refining, but due to customary reasons, electrolytic refining is not widely used in China.
For difficult to separate sulfide lead zinc mixed concentrates, the closed blast furnace smelting method that simultaneously produces lead and zinc is generally used for processing.
For the extremely difficult to separate mixed ore of lead and zinc oxide, a unique treatment method has been developed in China through long-term research, which involves using the raw ore or its enriched products of the mixed ore of lead and zinc oxide, sintering or pelletizing them, and melting them in a blast furnace to obtain coarse lead and molten slag containing lead and zinc. The slag is further fumigated in a fuming furnace to obtain zinc oxide products, and electrolytic zinc is obtained through wet zinc smelting. In addition, zinc oxide products can also be directly fumigated using a rotary kiln.
02. Classification of Lead
Classification of lead alloys
Lead alloys are mainly divided into corrosion-resistant alloys, battery alloys, solder alloys, printing alloys, bearing alloys, and mold alloys based on their properties and uses.
Classification of lead ingots
Lead ingots are generally divided into small ingots and large ingots
The small ingot is a rectangular trapezoidal shape with binding grooves at the bottom and protruding ears at both ends. The unit weight can be 48kg ± 3kg, 42kg ± 2kg, 40kg ± 2kg, and 24kg ± 1kg.
The large ingot is trapezoidal, with T-shaped protrusions at the bottom and gripping slots on both sides. The unit weight can be 950 kg ± 50kg, 500 kg ± 25kg.
Quality standards for lead ingots
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, and Pb99.940.