The high magnesia content in most laterite ores and the liquidus temperature of the furnace products necessitate these higher smelting temperatures, which in turn make necessary an extensive system of cooling blocks within the refractory lining of the furnace.
Nickel requires higher smelting temperatures (in the range of 1,350 °C [2,460 °F]) in order to produce an artificial nickel-iron sulfide known as matte, which contains 25 to 45 percent nickel.
The key to the Hismelt process, as opposed to the deep slag process, is its high-temperature, high-pressure smelting vessel.
Of the two drag forces, that due to circulation of liquid beneath the slag layer is by far the larger, but further research would be required to predict the slag-free area in real high-temperature smelting processes.
To recover large quantities of metals quickly from ores with a high metal content, smelting remains the most profitable route.
To achieve the high temperatures required for smelting, furnaces with forced-air draft were developed; for iron, temperatures even higher were required.
Compared to metal recovery using smelting at high temperatures, the bioleaching microorganisms can work at near ambient temperatures and generate few direct contaminants.
Waste slag which is created during precious metal smelting contains high levels of potentially toxic elements (PTE) which can be mobilised from unconfined deposits into the local environment.
The large quantity of electrical current employed in the process and the typically large-scale output quantities combine to make aluminum smelting a high energy consuming industry.
High exposure occurs in smelting and refining of the metal, as well as in battery plants (Fu and Boffetta, 1995).
