Assertion: lignite | /r/AtLocation | first hearth
Facets:
Source sentences:
text: Thereafter the temperature of the first hearth is controlled or raised to the approximate range of 1450° to 1620° F while admitting sufficient combustion air to the first hearth and to the remaining hearths to assure complete combustion of the volatiles at least within the first hearth and in the stack and to drive off a major portion of the moisture contained in the lignite while the lignite is in the first hearth.