Freeze lining formation on water cooled refractory wall

Abstract

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.

An investigation of factors influencing freeze lining behaviour

“…As a first approximation, a number of simplifying assumptions can be made. For example, if under thermal steady state conditions the parameters are constant, and no refractory lining as in (Kalliala et al 2015) is present, the steady state thickness of the freeze lining (Δx FL,ss ) can be described by Equation (3) (Thonstad and Rolseth 1983;Verscheure et al 2006;Jansson et al 2014).…”

Process innovations and sustainability in Finnish metallurgical industries

“…The development of refractory lining technologies has been important in the flash smelting as the fluid iron silicate slags and occasionally and locally high copper concentrations are very aggressive to the vessel construction. Today, the operational conditions also allow the use of freeze linings, generated by effective heat flux through the refractory lining and assisted by cooling elements (Kalliala et al 2015). Those measures have extended the campaign lives of flash smelting vessels from the early few months duration to several years.…”

Elastic damage characterization of an ilmenite smelter freeze lining

“…Fallah-Mehrjardi, Hayes, and Jak (2014) studied the effect of bath chemistry on the freeze lining microstructure of a copper smelting slag at the laboratory scale using the cold probe technique and found that the freeze lining formed depended on the viscosity of the slag bath. Kalliala et al (2015) also used the cold probe technique in a refractory sleeve to show that the freeze lining composition depends on the cooling rate of the freeze lining during formation.…”

“…Little work has been done to model the thermomechanical aspects of freeze linings, despite several comments on aspects that mechanically challenge the freeze line integrity (Kalliala et al, 2015;Crivits, 2016;Zietsman, 2004). A thermomechanical model was produced by Campbell, Pericleous, and Gross (2002) that made use of a computational fluid mechanics (CFD) model coupled with a thermomechanical module to model the penetration, corrosion, and erosion of the refractory in a HIsmelt process.…”