The present invention provides a process plant for the production of
molten steel from primary and/or secondary ferrous materials in which no
free oxygen is permitted to contact directly carbon-containing iron
melts, comprising:--i) at least three pairs of furnaces (1,2; 3,4;5,6),
each furnace of a pair having a hearth base (36) and being interconnected
so as to form a continuous flowpath loop for molten metal, the first pair
(1,2) defining an iron making loop (A) and the second and third pair
(3,4;5,6) defining primary and secondary steel refining loops (B,C)
respectively, (ii) means (8) for transferring molten metal from the
ironmaking loop (A) to the first refining loop (B) and from the first
refining loop (B) to the second refining loop (C), (iii) means for
controllably supplying heat to, and removing heat from metal in the
furnaces (1,2,3,4,5,6), whereby, in use a central region of metal (19a)
in the furnace (1,2,3,4,5,6) becomes or is maintained in its molten state
and a peripheral region of the metal (20) is maintained in a solid state
such that the molten metal (19a) is contained within a stable solid shell
of metal (20), said solid metal shell (20) defining the walls of the
furnace (1,2,3,4,5,6), (iv) for each furnace (1,2,3,4,5,6), a removable
lid (23), an enclosed space (25) being defined between the hearth (36),
the lid (23) and the solid metal shell (20) defining the walls of the
furnace (1,2,3,4,5,6), (v) a lifting arrangement (34,35) for controllably
raising out of and lowering into the melt any plant items, so that upon
shut down, said items can be removed prior to solidification of the
molten metal (19a).