Effect of temperature and alumina/caustic ratio on precipitation of boehmite in synthetic sodium aluminate liquor

Statistical Modeling of the Industrial Sodium Aluminate Solutions Decomposition Process

“…[7][8][9][10][11][12][13] The crystallization mechanism of Al(OH) 3 from sodium aluminate solutions was investigated by Li et al, [4] they indicated that the mineral form of obtained crystals, as well as their size distribution, depends on the concentration of the solution at temperatures ranging between 338 K (65°C) and 343 K (70°C). This was also proved in the investigations published by Dash et al [14] The kinetics of the gibbsite crystallization from the caustic sodium-aluminate solution, as well as size and the shape of obtained particles, depend on the following parameters of the process: temperature, alumina/caustic ratio, amount and size distribution of the crystallization seeds, stirring speed, and the presence of activation ions added to the solution. [3,7,14,15] Investigations of boehmite (AlOOH) precipitation from the aluminate solutions were reported recently, [14,16,17] with the aim to find sustainable alternative for the current technology of alumina production.…”

“…This was also proved in the investigations published by Dash et al [14] The kinetics of the gibbsite crystallization from the caustic sodium-aluminate solution, as well as size and the shape of obtained particles, depend on the following parameters of the process: temperature, alumina/caustic ratio, amount and size distribution of the crystallization seeds, stirring speed, and the presence of activation ions added to the solution. [3,7,14,15] Investigations of boehmite (AlOOH) precipitation from the aluminate solutions were reported recently, [14,16,17] with the aim to find sustainable alternative for the current technology of alumina production. In those investigations, boehmite precipitation was facilitated in the highly saturated solutions at temperatures greater than 373 K (100°C).…”

Experimental Simulation of Long Term Weathering in Alkaline Bauxite Residue Tailings

“…A similar conclusion was drawn by Mehta and Kalsotra [48], who observed conversion of gibbsite to boehmite under hydrothermal conditions only at temperatures ≥190 °C. Higher alumina to caustic ratios (A/C; Al2O3:Na2O ratio (g/L) in the supernatant) also raise the minimum transformation temperature [49,50]; the alumina:caustic ratio was consistently below 0.5 in this experiment and was therefore unlikely to have inhibited transformation of gibbsite to boehmite.…”

Development of a Kinetic Model of Boehmite Dissolution in Caustic Solutions Applied to Optimize Hanford Waste Processing

“…Prior work detailed in Skoufadis et al 2003, "Gibbsite to Boehmite Transformation in Strongly Caustic and Nitrate Environments" (Gong et al 2003), and Konigsberger et al 2006 have investigated the kinetics of boehmite precipitation from aluminate, while "Effect of Temperature and Alumina/Caustic Ratio on Precipitation of Boehmite in Synthetic Sodium Aluminate Liquor" (Dash et al 2007) investigated the kinetics of boehmite precipitation from gibbsite. Aluminum solids dissolution and speciation from radioactive sludge materials was analyzed in "Effects of Sodium Hydroxide and a Chelating Agent on the Removal of Aluminum from Radioactive Sludge" (Spencer et al 2005), "Modeling of Boehmite Leaching from Actual Hanford High-Level Waste Samples" (Peterson et al 2007), "Boehmite Actual Waste Dissolution Studies" (Snow et al 2008), and "Raman Study of Aluminum Speciation in Simulated Alkaline Nuclear Waste" (Johnston et al 2002).…”