Abstract
The corrosion of refractories by sodium salts in waste liquid at high temperature has become a serious problem. This paper focuses on the thermodynamic characterization of sodium carbonate (Na2CO3) corrosion of six refractories by FactSage modelling in combination with X-ray diffraction (XRD). Three of the refractories are oxides (Fe2O3, Al2O3, and Cr2O3), and the other three are synthetics spinels (magnesium chromium, MgO·Cr2O3; magnesioferrite, MgO·Fe2O3; and, magnesium aluminium, MgO·Al2O3). First, thermodynamic simulations were carried out with the FactSage thermodynamics model using the reaction package to predict the direction of the Na2CO3 corrosion reaction in terms of the Gibbs free energy. Then, the reactions between the six refractories and Na2CO3 were conducted through a series of refractories/Na2CO3 reaction tests. The XRD analytical method was used to describe and understand the chemistry and interpret mineral matter transformation. The products of the tests were also determined by X-ray diffraction and the experimental observations were compared with the results of the thermodynamic simulations. Furthermore, the strength of sodium corrosion of the refractory materials was comprehensively discussed. The results show that MgO·Al2O3 has the best thermal stability and it is hard to corrode by Na2CO3, while the chrome-containing refractory reacts easily with Na2CO3 with a considerably high amount of corrosion product at a temperature of 600 °C. These experimental results are in agreement with the thermodynamic calculations.
Highlights
With rapid industrialization, large amounts of waste are generated in production processes inChina
There are severe corrosion problems that are associated with refractories in steel refining furnaces [1], coal gasifiers [2,3], rotary kilns for the high-temperature calcination of cement [4], solid waste incinerators [5,6], liquid waste incineration boilers, and other industrial equipment
The three spinel refractories that were selected in this paper are commercially and describe the thermodynamic mechanism by which sodium carbonate reacts with the mineralogical commonly used refractories, which were synthesized in the laboratory
Summary
Large amounts of waste are generated in production processes inChina. The incineration technology is an effective and feasible treatment for organic compounds, because chemical waste liquids have a calorific value. This approach can recover and utilize the heat that is contained in high-concentration waste liquid, reduce the treatment cost, as well as burn off harmful substances towards environmental protection. There are severe corrosion problems that are associated with refractories in steel refining furnaces [1], coal gasifiers [2,3], rotary kilns for the high-temperature calcination of cement [4], solid waste incinerators [5,6], liquid waste incineration boilers, and other industrial equipment
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