Aluminum melting furnaces

Explosions with wet aluminum ingots in an aluminum melting furnace are cleaily exceptions. 

The industrially most important refractory products are supplemented by specialty products for particular applications. The most important of these is zirconia bricks. They are produced from natural zircon (ZrSi04) with optional addition of quartz or alumina using standard ceramic techniques. They are used in tank furnaces in the glass industry, aluminum melting furnaces and high temperature furnaces. 

FIGURE 6.1 Conventional air/fuel, single-pass, rotary aluminum melting furnace. 

Performance of Typical Side-Well Reverberatory Aluminum Melting Furnace... 

This work was sponsored by the U.S. Department of Energy under Contract No. DE-AC07-78CS40037, "Pulverized Coal Firing of Aluminum Melting Furnaces."... 

For flame types, see fig. 6.2.) Unlike crucible, pot, kettle, and dip-tank furnaces, the refractory furnace lining itself is the container for glass tanks and aluminum melting furnaces, figure 1.2. 

Aluminum-melting furnaces are often fired with regenerative burners (fig. 5.26), but care is necessary to prevent fouling the regenerative beds with carry-over from the melting process such as flux, oxides, and aluminum droplets (an operational mistake). 

Fig. 5.28. Tilting batch aluminum melting furnace with a pair of Integral regenerator-burners for heat recovery. Courtesy of Degulsa S.A.

Fig. 6.9. Direct-charged aluminum melting furnace with cascaded temperature control and regenerative burners. On the next 20-sec cycle, two air valves, two exhaust valves, and two fuel shutoff valves will reverse positions. Ma = milliamps. Se = suction exhaust. SP = setpoint. T/s = temperature sensor. Courtesy of North American Mfg. Co. 

Experimental test results for molten aluminum-water RPTs are described in Section V. Also shown is a tabulation of most documented aluminum-water explosive boiling incidents (see Table XIV). In many accidents, the quantity of water was quite small, e.g., some resulted when wet aluminum ingots were loaded into melting furnaces containing molten aluminum. In contrast, one notes that few, if any, serious events have ever been obtained when small quantities of aluminum were contacted with a large mass of water. Since laboratory tests were often carried out in the latter fashion, most of these have produced negative results. 

As above. An explosion resulted when charging aluminum scrap into a large melting furnace containing 14,000 kg of metal. The explosion was immediate after the scrap addition. An extensive investigation failed to find any definite cause, but judging from similar accidents, it was concluded that moisture had been present in the scrap... 

About 15 min after loading a 900-kg aluminum sow into a melting furnace, an explosion occurred. Later investigation showed the sow had a hidden internal cavity which could have held 0.015 m of water... 

Aluminum scrap (with moisture ) was being loaded in a melting furnace when an explosion resulted... 

A bad leak occuired in a melting furnace while casting. Significant quantities of aluminum may have contacted wet surfaces both on the superstructure of the casting machinery and in the bottom of the casting pit. Several explosions took place... 

An aluminum scrap fire developed near a melting furnace. Fire departments responded and sprayed water on the flames. Suddenly the pot furnace exploded. It is presumed that water from the fire hoses entered the furnace which contained about 900 kg of molten aluminum... 

A twin torch plasma furnace, where DC anode and cathode arcs were coupled together above an aluminum melt, was developed for synthesis of AIN UFPs in order to control the aluminum evaporation rate and the concentration of nitrogen atoms in the plasma column independently (19). A two-stage transferred-arc plasma reactor was built for AIN synthesis, where aluminum is evaporated in a transferred-arc plasma chamber and then reacted in a separate tubular reactor, allowing a better control of the reaction conditions (20). Arc plasma technique has been modified and... 

Quantification of furnace efficiency and productivity improvements using OEC in aluminum melting and... 

Another aspect of the geometry that is important in some applications is whether the furnace is moving or not. For example, in a rotary furnace for melting scrap aluminum, the furnace rotates to enhance mixing and heat transfer distribuhon. This again affects the type of testing that would be appropriate for that system and can add some complexity to the computations. 

Fig. 3.31. Sectional view of a tilting aluminum melting and holding furnace in Hungary that tips either left or right to fully drain its liquid load. This avoids the problem of the bottom portion of the next charged load of solids being shielded from furnace gas convection and radiation. Two burners in diagonally opposite corners are tilted downward 3.5 degrees from horizontal. (See also fig. 5.28.)...

In the aluminum industry, melting furnaces are made entirely out of monolithic refractories. The heating chamber is lined with high-alumina castable, while sections that are in direct contact with the metal are made from phosphate-bonded plastic refractory. 

Bricks in the 80% and 85% AI2O3 class were originally developed for use in aluminum melting and holding furnaces. It is rare that they find application in... 

Preparation. Uranium metal may be prepared by several methods the reduction of uranium oxides with carbon In an arc-melting furnace reduction of uranium oxides with magnesium, aluminum, calcium or calcium hydride the reduction of uranium halides with alkali or alkaline-earth metals electrolytic reduction of uranium halides and the themal decomposition of uranium Iodide. 

Yok] Yokokawa, H., Fujishige, M., Ujie, S., Dakiya, M., Phase Relations Associated with the Aluminum Blast Furnace Aluminum Oxycarbide Melts and Al-C-X (X = Fe,Si) Liquid Alloys , Metall. Trans. B, 18B, 433-444 (1987) (Review, Thermodyn., 74)... 

Aluminum and Hydrogen. Hydrogen [1333-74-0] is the only gas known to be appreciably soluble in soHd or molten aluminum. Hydrogen can be introduced into Hquid aluminum from reaction with moisture present in the furnace atmosphere or the refractories, or with moisture entrapped in the oxide film of the soHd aluminum before melting. The solubiUty of hydrogen in molten and soHd aluminum is shown in Table 6. 

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