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The oxidizing gases flow upward, i.e., counter-current to the descending charge. In a well-insulated roaster, external heating is unnecessary except when the charge is highly moist. The hearth at the top of the roaster dries and heats the charge. Ignition and oxidation of the charge occur lower down. [1]
The reactions are slow and can be sustained only by the addition of fuel. Multiple hearth roasters are unpressurized and operate at about 690 °C (1,270 °F). Operating time depends upon the composition of concentrate and the amount of the sulfur removal required. Multiple hearth roasters have the capability of producing a high-purity calcine. [1]
Early sulfide roasting was practiced in this manner in "open hearth" roasters, which were manually stirred (a practice called "rabbling") using rake-like tools to expose unroasted ore to oxygen as the reaction proceeded. This process released large amounts of acidic, metallic, and other toxic compounds.
An Uber customer found a lengthy list of passenger rules in the backseat during a recent ride — and it has people divided.. The rider shared a photo of the rules on Reddit on Jan. 9 and titled ...
The mother and daughter, as well as the four others on the plane, were all killed. A seventh person inside a vehicle was killed on the ground, while 24 others were injured, officials said.
To increase the difficulty of daily walks, experts recommend adding weights for resistance and walking quickly enough to be out of breath. - Sorrasak Jar Tinyo/Moment RF/Getty Images
Initial copper production used two multiple-hearth roasters, a single coal-fired reverberatory furnace and two Peirce-Smith converters to produce a design 1,500 tons of blister copper per month (18,000 tons per year). [20] The copper smelter produced 15,000 tons of copper during 1953. [21]
The U.S. Surgeon General's warning of an increased risk of cancer from drinking alcohol may end up resonating most with younger Americans - who in recent years were already turning to mocktails ...