Smelting Operations

There are no fumes or effluents generated in the processing of powders and the requirements of state and federal environmental protection agencies are met without difficulty. However, the production of powders has been subjected to the same concerns as most other metal refining and smelting operations. 

The obvious destination for nickel waste is in the manufacture of stainless steel, which consumes 65% of new refined nickel production. Stainless steel is produced in a series of roasting and smelting operations. These can be hospitable to the various forms of nickel chemical waste. In 1993, 3 x 10 t of nickel from nickel-containing wastes were processed into 30 x 10 t of stainless steel remelt alloy (205,206) (see Recycling, nonferrous metals). This quantity is expected to increase dramatically as development of the technology of waste recycle coUection improves. 

In addition to domestic production of Frasch and recovered elemental sulfur, U.S. requirements for sulfur are met with by-product sulfuric acid from copper, lead, molybdenum, and zinc smelting operations as well as imports from Canada and Mexico. By-product sulfur is also recovered as sulfur dioxide and hydrogen sulfide (see Sulfurremoval and recovery). 

The bismuth that is found in the lead ore accompanies the lead through the smelting operation right up to the last refining steps. The removal of bismuth then requires special techniques, the most common being the Betterton-KioU and the Betts processes (5). 

Developments in the metallurgy of copper or its alloys were mentioned in 1556 in De MetalBca where the process of copper ore was described by Agricola (see also Copper alloys). About that time, smelting operations commenced at Mansfield, Germany, and at the Swansea smelter in Wales. Both smelters employed successive oxidations and reductions to eliminate iron and sulfur. The process used in the Swansea smelter is similar to modern techniques. 

Fire refining, the final smelting operation, removes further impurities and adjusts the oxygen level ia the copper by air oxidation followed by reduction with hydrocarbons, ammonia, or reformed gas (CO + H2). 

The thermodynamics of copper smelting are discussed ia References 17 and 18. Silver and gold are quantitatively recovered with the copper throughout the smelting operations rather than being lost with the slag. 

S / S than ores of zinc (ZnS) have. Thus, the value of S / S in atmospheric SO2 can identify whether the source of pollutant was an iron or zinc smelting operation. 

The blast furnace is the most popular of the furnaces used for carrying out reduction smelting operations. An illustrious example of a blast furnace smelting product is iron. 

Some very unique opportunities are also exclusively available to the primary metals industry. For example, the use of dry air control devices and dry cast quench operations have been adopted at some facilities to avoid the generation of contaminated wastewater. Additionally, many facilities are finding markets for byproducts (e.g., sulfides resulting from nonferrous smelting operations can be converted to sulfuric acid and subsequently sold) which avoids the need to discharge these contaminants.24 25... 

The major uses of quicklime are as a component of ordinary glass, as a flux in metal smelting operations and (mostly), for making building cement and mortar (see Textbox 34). 

Palmer KT, Kucera CL. 1980. Lead contamination of sycamore and soil from lead mining and smelting operations in eastern Missouri. Journal of Environmental Quality 9 106-111. 

---