Kinetics of corrosion of refractories by a high-alkali container-glass melt

Abstract

The corrosion of refractory materials by melts of silicate glasses determines the useful life of the glass-melting furnaces and is a typical heterogeneousreaction obeying the laws of diffusion kinetics [i, 2]. In research on this process the dissolution of single crystals of a series of chemically stable oxides in silicate melts of a simple composition has mainly been studied [3][4][5]; this has limited the possibilities of using the results obtained to reveal the mechanism of the interaction between multiphase refractories and multicomponent silicate glass melts. Results published in recent years of the corrosion kinetics of fused-cast refractories in industrial glass melts [6][7][8] have been insufficient to forecast the resistance of the refractory lining under actual operational conditions.The main factor which limits the length of campaign of glass-melting tank furnaces of the throat type producing container glass and high-quality glassware is the intense corrosion of two elements of the lining: the walls of the melting tank and the blocks covering the throat [9].The corrosion by molten glass Of the refractory in the wall of the melting tank at the level of the free surface of the glass under conditions where there are three phase interfaces and the intense convection of the melt characteristic of a glass-melting furnace has mainly been modeled by static corrosion tests [i0]. The kinetics of the surface corrosion of the refractory under these conditions can be calculated using the equation in [ii]:where Ad is the average thickness of the corroded layer of refractory; T is the interaction time; and K is the rate constant of the corrosion.The corrosion of thethroat blocks and some of the other design elements of the lining of glass-melting furnaces whose lower horizontal surface is in contact with the molten glass is determined by the vertical cellular corrosion [12, 13J.The vertical cellular corrosion is the main form of wear on the refractory in glass furnaces. The horizontal downward-facing surfaces of the refractories are mainly damaged by this wear (the throat blocks, Bakor paving on the bottom when the glass has penetrated underneath it, antistriae bridges and floats, the horizontal seams in the walls of the tank, etc.). The mechanism of corrosion has been associated with the presence of gas bubbles on the refractory-glass contact surface. A gas bubble can be trapped from the glass or liberated by a pore or crack on the down face of the refractory surface. The bubble, as a result of a change in the surface tension of its film and also under the effect of gravity, completes rotary and to-andfrom (up-and-down) movements in the contact zone with the refractory and continuously brings Gusev Branch, State Institute of Glass. State Institute of Glass.