The leaching behavior of Tunceli smithsonite ore in nitric acid was evaluated in two study steps including optimization of leaching process and kinetics modeling. The individual and synergistic effects of effective parameters such as nitric acid concentration, solid-to-liquid ratio, stirring speed, and temperature on the dissolution rate of zinc were investigated using central composite design. Four factors including temperature (30–50 °C), nitric acid concentration (0.2–0.5 mol/L), stirring speed (350–600 rpm), and solid-to-liquid ratio (0.004–0.01 g/L) were investigated. The dissolution percent of zinc (97%) was obtained in 120 min of leaching time: acid concentration 0.5 mol/L, temperature 50 °C, stirring speed 500 rpm, and solid–liquid ratio 2/500 g/mL at the optimum conditions obtained using the central composite design. The dissolution kinetics of smithsonite was examined according to heterogenous models and it was found that the dissolution rate was controlled by ash layer diffusion process. It was found that the leaching rate increased with increasing temperature, stirring speed, and acid concentration as well as decrescent particle size and solid/liquid ratio. The trial data were analyzed by statistical and graphical methods and the activation energy of this leaching process was determined to be 28.63 kJ·mol⁻¹.

Graphical Abstract

中文翻译：

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中心复合设计法确定最佳工艺条件及用硝酸溶液法考察铁矿浸出动力学。

通过优化浸出过程和动力学建模这两个研究步骤，对通塞利史密森铁矿石在硝酸中的浸出行为进行了评估。采用中心复合设计研究了硝酸浓度，固液比，搅拌速度和温度等有效参数对锌溶出速率的单独和协同作用。研究了四个因素，包括温度（30–50°C），硝酸浓度（0.2–0.5 mol / L），搅拌速度（350–600 rpm）和固液比（0.004–0.01 g / L）。 。在最佳的条件下，在120分钟的浸出时间内获得了锌的溶解百分比（97％）：酸浓度0.5 mol / L，温度50°C，搅拌速度500 rpm，固液比2/500 g / mL使用中央复合设计获得。根据异质模型研究了新铁矿的溶解动力学，发现其溶解速率受灰层扩散过程的控制。发现浸出速率随着温度，搅拌速度和酸浓度的增加以及新月粒径和固/液比的增加而增加。通过统计和图形方法分析了试验数据，确定该浸出过程的活化能为28.63 kJ·mol^-1。

图形概要