To a recycler, an object such as an automobile transmission resembles a piece of candy in which the wrapper is more desirable than what’s inside. The aluminum of the casing is more valuable than the steel gears and other contents it holds. But most recyclers find that manually separating such transmission cases from their contents is usually prohibitively costly.
For these recyclers, sweat furnaces offer an effective and affordable way to separate non-ferrous metals such as aluminum from less-valuable iron and steel. Sweat furnaces heat commingled recyclable metals to a temperature that causes the non-ferrous metals to melt and run off, leaving behind steel and other materials that melt at higher temperatures.
At sweat furnace maker EnviroAir, Inc. in Eagle, Wisconsin, CORECO Product Manager Dean Lesch said modern machines like those his company makes provide several appealing features. Compared to traditional sloping hearth sweat furnaces, recyclers don’t need to manually rake off iron and other non-melting contaminants. They also avoid impinging flames directly on molten aluminum, which creates dross. Other designs may also allow iron to dissolve into aluminum. Most importantly, up-to-date equipment meets ever-tougher environmental regulations. Read more