Abstract: In a shaft furnace having a metal shell, a refractory lining of relatively high thermal conductivity and cooling bodies which project inwardly through the shell into the lining and through which in operation cooling liquid flows, has a high uniformity of temperature in the lining. In order to improve its operational characteristics, in particular to improve temperature uniformity yet further while reducing heat loss, the shell and the cooling bodies are screened from the lining. Between the cooling bodies and the refractory lining and between the shell and the refractory lining there are respectively first and second thin layers of refractory material having in each case a .lambda.-value of less than 5 kcal/mh .degree.C., preferably less than 1.5 kcal/mh .degree.C. The thin layers may be of refractory felt or refractory plates.

Abstract: In a shaft furnace having a metal shell, a refractory furnace lining inside the shell and a taphole construction comprising a drilled taphole extending through a plug located in an aperture in the shell and a taphole brick structure forming part of said furnace lining, the taphole brick structure at least partly consists of at least one taphole brick of high thermal conductivity material selected from the group comprising graphite, semi-graphite and material of equivalent heat conductivity, there further being screening means comprising material of substantially lower heat conductivity coefficient than graphite and semi-graphite located between said taphole brick and said furnace shell.