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This post was last edited by chengjchyxl on 2010-7-9 at 22:56. 1. Technical background: On March 23, 2007, the price of lead ingots on the London Metal Exchange (www.lme.co.uk) was $1,940 per ton in cash, and this price has shown an upward trend over the past few years. Figure 1 shows the variation in the price of lead ingots on the London Metal Exchange since 2003. The price of lead in China is generally determined by referring to the selling prices of lead ingots on the London Metal Exchange, with appropriate adjustments made based on the production and sales activities of several major lead manufacturers in the country. Therefore, domestic lead prices have also shown an upward trend in recent years. In 2006, global consumption of refined lead was 8.05 million tons, with the majority of this going into lead-acid batteries, accounting for about 70% of total lead consumption. The main end-use areas for lead-acid batteries are the automotive industry (excluding agricultural and military vehicles) and the electric vehicle sector. Next are lead oxide, lead alloys, and lead products. Lead, as an excellent material for shielding against radioactive rays, is irreplaceable by other metals and is an essential material for the development of nuclear power. In 2006, global production of refined lead was around 8 million tons, of which China produced about 2.68 million tons, ranking first in the world. Currently, almost all industrial production of lead metal relies on pyrometallurgy; enterprises that use the traditional processes of sintering and roasting followed by reduction and smelting in blast furnaces account for over 75% of all lead-producing companies, and their output constitutes more than 80% of the world’s total lead production. In our country, with the exception of a few factories that use the ISP method, all others employ the traditional sintering-blast furnace reduction smelting process. This process uses lead sulfide concentrate as raw material; in order to ensure product quality and the smooth progress of production during the metallurgical process, it imposes high requirements on the composition of the lead concentrate: (1) The content of the main metal should not be too low, with a requirement of usually more than 40%. However, too high a content also poses many difficulties for normal sintering, leading to the addition of large amounts of solvent, recycled powder, and slag. (2) The impurity copper content should not be too high; it is generally required to be less than 1.5%. (3) Zinc sulfides and oxides have high melting points and high viscosity; if the zinc content is too high, these zinc compounds will enter the slag and lead matte during the smelting process, raising their melting points, increasing their viscosity, reducing the density difference, and making separation difficult. Therefore, the zinc content should not be too high, generally it should be less than 5%. (4) There are also strict requirements for the content of impurities such as arsenic and antimony; generally, As+Sb is required to be less than 1.2%. (5) Impurities such as MgO and Al2O3 also affect the slag type in blast furnaces; therefore, generally, MgO levels are required to be controlled