Pollution control and energy consumption at U.S. copper smelters

Abstract

The current trend is to replace reverberatory smelting with smelting processes which more efficiently utilize the fuel value of the concentrate feed and produce waste gases from which the sulfur oxides can be more easily recovered. To determine the influence of pollution control on smelter energy consumption the fuel and electricity consumption for a hypothetical domestic copper smelter before pollution control is established. Fuel and electricity requirements for alternate smelting processes and pollution control processes are also established and compared to the requirements of the pre-pollution control smelter. The energy consumed for the pre-pollution control smelter includes a credit for surplus electrical energy. The credit taken is equal to the quantity of hydrocarbon fuel required to generate the surplus. The value of the credit is about 27 x 10/sup 8/ Btu/day. It is seen that the low net energy consumption of the prepollution smelter is approached when a process, including pollution contol, is used which utilizes a large fraction of the fuel value of the concentrate and which includes oxygen enrichment. Inclusion of adequate pollution control into the reverberatory smelting process doubles the energy consumption. Accompanying utilization of concentrate fuel value and/or oxygen enrichment are waste gases of relatively highmore » sulfur dioxide concentration. These gases are handled and processed for sulfur oxide recovery at relatively low energy expenditures. Oxygen enrichment is shown to reduce the hydrocarbon fuel consumption of the Noranda smelting process by more than 50%. A similar improvement may be expected for the Outokumpu flash smelting process. However, the large oxygen plant electricity requirement reduces the overall improvement on an equivalent energy basis to about 20% for either process.« less