Abstract: A process for cleaning a surface of a refractory structure which is at an elevated temperature, including projecting against the surface a comburent gas stream which is a powder stream including fuel particles carried in an oxygen-containing carrier gas the comburent gas stream impinging upon the surface at an impingement zone, whereby the fuel particles are caused or allowed to burn in a reaction zone defined generally around the impingement zone and the heat generated by the combustion of the fuel particles causes the surface or material adhered thereto to melt and provide a melted material, and projecting a scouring stream including oxygen simultaneously or alternately at the surface to scour the surface in the vicinity of the reaction zone and thereby clean the surface due to the scouring stream blowing away the melted material.