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

Abstract

Incineration of high-content sodium salt organic waste liquid will corrode the refractory material in the incinerator, causing the refractory material to peel off and be damaged. A thermodynamics method was used to study the thermodynamic properties of three common sodium salts (NaCl, Na2CO3 and Na2SO4) on the corrosion of refractory materials (MgO·Cr2O3, MgO·Al2O3, Al2O3, MgO and Cr2O3). The results determined that MgO has the best corrosion resistance and is not corroded by the three sodium salts. On this basis, the thermodynamic corrosion experiments of NaCl corrosion of magnesium oxide at three temperatures of 600, 1000 and 1200 °C were carried out. Analysis of the corrosion product by X-ray diffraction (XRD) showed no corrosion product formation. Studies have shown that thermodynamic calculation can accurately predict the thermodynamic mechanism of alkali metal corrosion to refractory materials, and MgO is a good anti-alkali metal corrosion refractory material.

Reaction Mechanism and Technical Application of Metallic Bismuth Extraction from Bismuthinite Concentrate by Low-Temperature Alkaline Smelting

“…Under the optimized conditions (850 °C, 1.5 h, W NaCl / W Na2CO3 / W ore / W coke = 0.6:2.4:1:0.1), the direct metallic bismuth recovery and crude bismuth grade are 97.71 and 91.81%, respectively. However, when the melt contains NaCl, the MgO·Cr 2 O 3 and MgO·Al 2 O 3 in the refractory react with NaCl at high temperatures to form NaAl 9 O 14 , Na 2 CrO 4 , and Cl 2 , which consequently aggravates the furnace refractory damage . Currently, the bismuth extraction mechanism from bismuthinite concentrate is unclear, and, to the best of our knowledge, the reaction behaviors of chalcopyrite, pyrite, molybdenite, and other associated minerals have not been studied yet.…”

“…However, when the melt contains NaCl, the MgO•Cr 2 O 3 and MgO•Al 2 O 3 in the refractory react with NaCl at high temperatures to form NaAl 9 O 14 , Na 2 CrO 4 , and Cl 2 , which consequently aggravates the furnace refractory damage. 22 Currently, the bismuth extraction mechanism from bismuthinite concentrate is unclear, and, to the best of our knowledge, the reaction behaviors of chalcopyrite, pyrite, molybdenite, and other associated minerals have not been studied yet. Therefore, in this study, the alkaline smelting mechanism of bismuthinite concentrate and bismuth extraction pathways are revealed through thermodynamic simulations and reaction product characterizations, and the technical parameters and industrial application prospects of this process are evaluated.…”

Formation and Growth Behavior Analysis of Slagging Rings in Rotary Kiln-Type Hazardous Waste Incineration Systems

“…At the same time, cohesive fly ash and gas-phase metals entering the secondary combustion chamber from the rotary kiln will further enhance the slagging phenomenon at the flue exit of the secondary combustion chamber [22]. However, most studies focus mainly on the impact of slag deposits on the refractory lifetime in hazardous waste treatment systems [19,[22][23][24], while little systematic attention has been devoted to analyzing the formation behavior of slagging rings on the hot face of linings. With the continuous improvement of refractory performance, the influence of slag on the lifetime of refractories is gradually weakened [25][26][27].…”