The experimental study was focused into effects of a ceramic refractory lining, covering a metallic cooling element, as well as to properties and microstructures of the freeze lining formed in such cases in copper smelting and converting slags. The modified heat transfer pattern, due to the ceramic refractory lining and its air gap(s), increases effectively the average freeze lining temperature, heating its cold face from 30 to 50°C of the direct contact close to 800–900°C, even with refractory thicknesses of a few millimetres. This general feature has direct consequences to the microstructure and thickness of the freeze lining and probably also to its growth rate. The observations about effects of high copper iron silicate slag on the chemical corrosion of direct bonded magnesia–chromia refractories suggest that copper oxides are not the most aggressive components of direct to blister smelting slags. Impregnation of the fluid direct to blister slag into the open porosity of the brick, even on the cooled furnace wall, extends quickly in the initial contact several hundred micrometres into the refractory.