4 Refractories - Reactor materials Refractories Containment...

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1 Refractories Reactor materials • Containment of high-temperature (often molten) products • Insulation – prevent excessive loss of energy • Maintain shape and mechanical strength • Most common temperature-resistant (‘refractory’) materials are based on the oxides SiO 2 , Al 2 O 3 , MgO, and Cr 2 O 3 High-temperature construction materials http://www.gsceramics.com/ gsc_brochJJ.jpg (Thailand) Special purpose refractory bricks Kiln construction Installation of DC arc furnace hearth and sidewalls
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2 Important properties of refractories • Refractoriness • Resistance to chemical attack • Resistance to erosion • Thermal conductivity • Resistance to thermal shock • Compressive strength • Low thermal expansion • Refractoriness Refractories must be able to maintain their strength and shape at the processing temperatures that are employed – over 2000ºC in some cases. • Resistance to chemical attack The environment inside a pyrometallurgical reactor is chemically very aggressive. Unless the chemical composition of the refractory is chosen carefully, the contents of the reactor, particularly the slag, can cause rapid dissolution or degradation of the refractory. • Resistance to erosion Physical erosion of a refractory can be caused by fast-moving solid particles or liquid droplets carried in the reactor gases. • Thermal conductivity It is often desirable for a refractory to have a low thermal conductivity so as to minimize the loss of energy from the reactor. • Resistance to thermal shock Sudden changes in temperature will occur from time to time. These cause thermal shock that can promote physical cracking and failure in brittle materials. • Compressive strength
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This note was uploaded on 05/13/2011 for the course METALLURGY 1133 at Murdoch.

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4 Refractories - Reactor materials Refractories Containment...

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