Refractory Selection Criteria
Refractory selection criteria for aluminum smelting holding furnace
Low silica, iron oxide and calcium oxide content
Resistance to molten aluminum melting infiltration
Sufficient strength against mechanical shock
In the process of using aluminum furnace lining, due to a large number of cracks in the furnace wall and flaking of the furnace lining, the overall expansion of the side wall causes the steel structure of the furnace to be deformed or the temperature of the furnace wall is too high, and the heat dissipation is serious. All of this is related to the occurrence of corundum slag in the refractory material of the furnace wall. The main chemical reactions occur are:
3(Al2O3 - SiO2 ) + 8Al →6Si + 13Al2O3
Aluminum reacts with silicon oxide in the furnace lining refractory material to reduce Si, which causes aluminum melting to increase silicon, and at the same time increases the proportion of alumina in the furnace wall refractory material. The reaction is expansion reaction, which will destroy the lining refractory structure. Show).
Alcoa alkali corrosion test for roof and upper wall material? K2CO3 + NaCO3 @ 900oC 5 hours
The carbonate base mainly forms a low melting point phase with the furnace-lined alumina silica, thereby reducing the service life, and the carbonate further reacts with the cement hydration phase:
Na2CO3+ CAH10→ CaCO3+Na2O.Al2O3+ 10H2O
Medium-casting refractory selects low impurity content (low Fe2O3, low Na2O), low cement and ultra-low cement castable in the upper furnace wall and furnace bottom, and adopts micro-powder technology and new water-reducing agent technology to make the material very dense. The structure of the body, medium-cast refractory for the upper wall materials ULTRA-FLO 71 and ALU-FLO 80 have good resistance to alkali corrosion.
Alkali corrosion test of ULTRA-FLO 61 material
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