Thermodynamic Study of the Corrosion of Refractories by Sodium Carbonate

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.

Analysis and Prediction of Corrosion of Refractory Materials by Sodium Salts during Waste Liquid Incineration—Thermodynamic Study

“…The experimental results and simulation results by FactSage TM 7.2 software (see Table 3 ) indicated that MgO is an excellent refractory, which can avoid NaCl corrosion. According to our previous thermodynamic experimental research [ 23 ], the thermodynamic model of the software can accurately predict the thermodynamic mechanism of alkali metal corrosion to refractory materials.…”

“…Similar to our previous work [ 23 ], the experiment was conducted in a high-temperature tube furnace ( Figure 1 ). A 1:1 molar ratio of NaCl and MgO was put into a corundum boat and full mechanical mixing was carried out.…”

“…A 1:1 molar ratio of NaCl and MgO was put into a corundum boat and full mechanical mixing was carried out. The rest of experimental and data analysis procedures were all the same as previously reported [ 23 ].…”

Natrium Karbonat : Termodinamika dan Transport Ion

“…Proses produksi bahan alkali natrium karbonat sudah dilakukan dari zaman kuno sampai tahun 1800-an berupa pembakaran vegetasi darat dan air laut yang diikuti oleh proses kalsinasi pada panas (221;235) yang menyala (238;239) dan pencucian abu. Soda abu atau natrium karbonat yang diperoleh dengan cara ini merupakan bahan yang rendah; misalnya, Barilla Spanyol berisi 25 -30% natrium karbonat (33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46), Varec dari Normandia 3 -8%, dan rumput laut Skotlandia 10 -15%. Soda abu diperoleh dari tanaman (234;241) sangat mahal dengan menggunakan proses yang terlalu kuno untuk mendapatkan produk massal dan menghabiskan banyak vegetasi.…”

Alkali resistance testing methodology and development: Focus on mullite based castables

“…Alkali's attack on aluminosilicate castable refractories has been a long-term problem in the industry. [1][2][3] Alkali vapors can condense in available pore space and lead to either a corrosive melt or react to form solid phases that can lead to physical damage of the refractory due to volume expansion. 4 Overall, the operation of aluminosilicate refractories in an alkali-rich environment will negatively impact the service life of the refractory.…”