Forsterite bricks

Other industrially important basic products are forsterite and dolomite bricks. Forsterite bricks are manufactured by firing naturally occurring low iron olivine, a mixed crystal of 2Mg0 Si02 (forsterite) and 2FeO Si02 (fayalite). 

As shown in Table 13, the magnesia-zircon brick exhibited 6.7% volume expansion during the test, while the magnesia-forsterite brick without zirconia exhibited only 0.93% voiume expansion. The volume expansion of the magnesia-forsterite brick without zirconia approached the 0% volume expansion exhibited by the burned magnesia brick sample, which was known to have good alkali resistance. 

Magnesia-Zircon Brick Magnesia-Forsterite Brick Without Zr02 Burned Magnesia Brick... 

Alkali resistance, of course, is not the only property of importance for a forsterite-bonded brick. Physical properties, including creep resistance, are of high interest. As shown in Table 14, the properties of the magnesia-forsterite brick without Zr02 were comparable to those of the magnesia-zircon brick. Modulus of rupture at 1482° C was somewhat lower for the magnesia-forsterite brick without zirconia, but the strength was considered to be adequate for a condensate zone. 

Forsterite is magnesium silicate. The origin of this refractory is olivenes. On decomposition, olivenes gives rise to serpentine, talc, and steatite. All these minerals are used to make forsterite bricks. The magnesia content in the bond is increased by adding very fine MgO. The mixture is then dry-pressed to make the brick. The green bricks are then fired. 

In olivenes, FeO is an impurity. This impurity tends to reduce the refractoriness of forsterite bricks. The iron content is adjusted to get a refractoriness of 1750°C. The RUL value minimum is 1550°C. Thermal expansion is low, which results in a moderately good spalling resistance. Fosterite is resistant to both acid and basic slags. Its resistance to acid slag is not as much as that of silica, and its resistance to basic slag is not as much as that of chrome-magnesite. 

Temp, °C Fkeday SiHca Brick Magnesite Chrome Forsterite MulHte Cristobahte Peridase Comndum... 

Other types of refractory that find use are forsterite, zirconia, and zircon. Acid-resisting bricks consisting of a dense body like stoneware... 

Other types of refractory that find use are forsterite, zirconia, and zircon. Acid-resisting bricks consisting of a dense body like stoneware are used for lining tanks and conduits in the chemical industry. Carbon blocks are used as linings for the crucibles of blast furnaces, very extensively in a number of countries and to a limited extent in the United States. Fusion-cast bricks of mullite or alumina are largely used to line glass tanks. 

Temp, °C Fireclay Silica Brick Magnesite Chrome Forsterite Mullite Cristobalite Periclase Corundum... 

They are normally cast in the form of brick and are sometimes bonded to assure stability. The outstanding property of these materials is their ability to act as insulators. The most important are fireclay (aluminum silicates), silica, high alumina (70-80% ALjOj), mullite (clay-sand), magnesite (chiefly MgO), dolomite (CaO-MgO), forsterite (MgO-sand), carbon, chrome ore-magnesite, zirconia, and silicon carbide. (2) Characterizing the ability to withstand extremely high temperature, e.g., tungsten and tantalum are refractory metals, clay is a refractory earth, ceramics are refractory mixtures. 

Current practice is to use magnesia-zircon brick that contain 14 to 19% forsterite in lower checkers when V2O5 attack is anticipated The potential for liquid formation is dependent on many factors, including the concentration of V2O5 and the temperature at which the checker is operating. In addition, soda attack on forsterite can be a consideration under certain conditions, such as in reducing atmospheres. 

Figure 6. Forsterite-bonded magnesia brick with no Zr02 after alkali vapor test (Altered hot face) SOX...

This paper described some of the principal wear mechanisms of basic refractories used in glass tank regenerators. Alteration of refractories by V2O5 and depletion of CaO from refractories exposed to sodium sulfate was discussed. Alkali attack on forsterite-bonded basic brick was described. Properties of a new type of forsterite-bonded brick that offers the potential for improved performance were presented. 

Routschka et al. Studies on the behaviour of magnesia, spinel and forsterite refractory bricks under simulated service conditions in the middle regions of oil-fired glass furnace regenerators. Glastech. Ber. Glass Sci. Technol. 63 (1990), no.3, pp. 61-68. 

A minor class of basic brick is manufactured from olivine (MgFe)2Si04. The major phase present is forsterite. 

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