Bosh region

Van Vlack [42] observed that the bosh region contained alkalies in excess of the requirements of kaliophilite and nepheline. This excess did not result in the formation of alumino-silicate or silicate minerals of higher alkali content but was present as alkali carbonates. The carbonates formed toward the end of the furnace campaign from the free alkali deposited in the bosh lining. For the particular furnace examined, Van Vlack determined that alkali-bearing minerals were present only where porosity and proximity of the surface permitted expansion. Therefore, the presence of alkalies did not prove seriously detrimental in the bosh and... 

In the iron blast furnace, the descending burden loses most of its mechanical strength at a temperature somewhat below its melting point. Burden descent is improved and pressure drop across the bosh region is reduced if... 

In the center of the lining Van Vlack [42] detected the absorption of 8% alkali. The high porosity of this region was attributed to carbon disintegration of the refractory. For the inside of the bosh area a coating of carbon and alkalies was observed with the sample containing as much as 42% alkali. The refractories involved are in the 40% to 45% alumina class. 

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