Abstract: A process for treating mud produced during gas scrubbing in a blast furnace comprises decanting water from the mud to produce a mud concentrate which is still free flowing and adding a reducible carbon additive to the concentrate. The resultant mixture is passed to a rotary tube furnace where it is dried and then heat treated at a temperature of 900.degree. C. to 1300.degree. C. so as to ensure agglomeration, volatilization of zinc and lead and at least partial reduction of iron oxides in the mixture. After discharge and cooling, the material from the furnace is added to charge material for iron making.