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Extractive Metallurgy of Copper Part 9

Tham khảo tài liệu 'extractive metallurgy of copper part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | CHAPTER 14 Capture and Fixation of Sulfur About 85 of the world s primary copper originates in sulfide minerals. Sulfur is therefore evolved by most copper extraction processes. The most common form of evolved sulfur is so2 gas from smelting and converting. SO2 is harmful to fauna and flora. It must be prevented from reaching the environment. Regulations for ground level so2 concentrations around copper smelters are presented in Table 14.1. Other regulations such as maximum total so2 emission tonnes per year percent SO2 capture and SO2-in-gas concentration at point-of-emission also apply in certain locations. In the past so2 from smelting and converting was vented directly to the atmosphere. This practice is now prohibited in most of the world so most smelters capture a large fraction of their so2. It is almost always made into sulfuric acid occasionally liquid so2 or gypsum. Copper smelters typically produce 2.5 - 4.0 tonnes of sulfuric acid per tonne of product copper depending on the S Cu ratio of their feed materials. This chapter describes a offgases from smelting and converting b manufacture of sulfuric acid from smelter gases c future developments in sulfur capture. 14.1 Offgases From Smelting and Converting Processes Table 14.2 characterizes the offgases from smelting and converting processes. SO2 strengths in smelting furnace gases vary from about 70 volume in Inco flash furnace gases to I volume in reverberatory furnace gases. The so2 strengths in converter gases vary from about 40 in flash converter gases to 8 to 12 volume in Peirce-Smith converter gases. 217 218 Extractive Metallurgy of Copper Table 14.1. Standards for maximum so2 concentration at ground level outside the perimeters of copper smelters. Country Time period Maximum so2 SOj concentration parts per million U.S.A. Yearly mean 0.03 EPA 2001 daily mean 0.14 3-hour mean 0.5 Ontario Canada Yearly mean 0.02 St. Elot et al. 1989 daily mean 0.10 recommendation 1-hour mean 0.25 0.5 hour average 0.3