Se identificaron los factores que inciden en el incremento de la concentración del níquel disuelto en la suspensión de carbonato básico de níquel, de la tecnología de lixiviación de carbonato amoniacal. Se propuso un modelo estadístico para determinar el níquel en función de los factores: concentración de amoníaco, dióxido de carbono y azufre en la solución que alimenta a las columnas de la destilación, y el pH de la suspensión. El modelo se validó con antecedentes experimentales y una serie de ecuaciones del equilibrio termodinámico en el sistema Ni (II)-NH3-CO32--S2O32--SO42--H2O. Se obtuvo que a mayor relación de Ni/S y CO2/S, y menor de NH3/CO2, disminuye el níquel disuelto. Cuando la alcalinidad de la suspensión disminuye a pH inferior a 9, hay una tendencia al incremento de la concentración de níquel disuelto. El análisis permitió formular las posibles reacciones químicas involucradas en la lixiviación del carbonato que propician el incremento del níquel disuelto.
The distillation process in the Ammoniacal Carbonate Leaching technology was studied at bench-scale and on industrial scale. The dissolved sulfur effect in the Product-liquor that feeds to the columns, on the Basic Nickel Carbonate (BNC) properties and the operation expenses was determined. When increasing the sulfur in the liquor, we augment the selectivity towards the sulfate formation in the BNC molecule; therefore the energy consumption to the BNC thermal decomposition in the calcination process increases. Also, the nickel dissolved in the columns effluent increases due to complex reaction with [SO42–] and [S2O32–] ions, thus the expenses for consumption precipitation reagent increase too. Feeding carbonated liquor in the range 1.60 ≤ NH3/CO2 < 1.80 and CO2-rich solution increases the CO2 in the BNC with decreasing in sulfate; then, the mean diameter particle increases, the filtration resistance and the cake moisture diminish, which augments the productivity and reduces the energy consumption in the process of filtration and calcination. Keeping a pH between 8.4 and 8.7 in the columns outlet the greatest economic benefit is obtained of 0,125 ($ · h–1) per (m3 · h–1) of Product-liquor.
Una investigación que contribuye al análisis del impacto del gasto público en el crecimiento económico, así como a identificar el tamaño de los multiplicadores fiscales en México, Centroamérica y la República Dominicana.
This study reports nickel removing by electrocoagulation of Ni(II)-NH3-CO2-SO2-H2O system at laboratory scale. Experiments were done using Al/Al pair electrodes at initial nickel concentration between 293 and 1356 mg L–1 and under operation parameters of pH 8.6, current density 9.8 mA cm–2, electrolysis time 30 min, and temperature 60 °C. The obtained results show removal efficiencies between 97.7 and 99.7%. Kinetics modeling suggested combined effects of external diffusion and nucleation, and as controlling step the chemical reaction and a possible autocatalytic contribution. The process followed the Langmuir´s isotherm with a maximum adsorption capacity of 7519 mg g–1. ICP-OES, XRD and FTIR characterization of the precipitates indicated a typical Ni-Al layered double hydroxide structures with 33.4–40.7% nickel and 6.3–7.0% aluminum depending on initial nickel concentration. The operation costs of energy and electrode consumption were 320–537 $ t–1 of removed nickel.
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