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Generalized shrinking particle model of leaching: Effect of the order of surface chemical reaction, liquid-to-solid ratio and non-ideal behaviour of the liquid phase
Hydrometallurgy ( IF 4.7 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.hydromet.2020.105441
Ľuboš Popovič , Pavel Raschman , Ján Spišák , Alena Fedoročková , Gabriel Sučik

Abstract A generalized non-porous shrinking particle model (G NSPM) of leaching has been verified and used for numerical simulations. Unlike the commonly used “simple” non-porous shrinking particle model (S NSPM), the G NSPM assumes n−th order chemical reaction, the influence of the L/S ratio and non-ideal behaviour of the leach solution. The leaching of dead-burned magnesite with hydrochloric acid has been chosen to verify the proposed mathematical model, as the (apparent) reaction order for HCl, n, may be both positive and negative, depending on the HCl concentration. Comparison of the simulations with experiments revealed that the S NSPM does not reflect the qualitatively different leaching behaviour at positive and negative n, especially at near-to-stoichiometric HCl/MgO ratio. The G NSPM reflects the effect of n not only qualitatively, but also with acceptable accuracy. At the stoichiometric HCl/MgO ratio, the mean squared error of the predictions obtained using the S NSPM was 100–130 rel. % as compared to those provided by the G NSPM. The common effect of the reaction order, n, L/S ratio (represented by the reduced HCl/MgO molar ratio, ϕ) and non-ideal behaviour of the acid were studied in detail by means of numerical simulations. The values of parameters n and ϕ can alter the leaching behaviour qualitatively. In contrast, the activity coefficient of HCl only slightly modifies the shape of the kinetic curves, but does not change the overall picture. The error of the time for complete conversion of MgO calculated using the S NSPM can reach more than 100 rel. % for n = − 0.5 and even up to several hundred rel. % for n = 1, because the conversion vs. time curves predicted by the G NSPM are markedly skewed towards longer leaching times.

中文翻译:

浸出的广义收缩粒子模型:表面化学反应顺序、液固比和液相非理想行为的影响

摘要 对浸出的广义无孔收缩粒子模型(G NSPM)进行了验证并用于数值模拟。与常用的“简单”无孔收缩粒子模型 (S NSPM) 不同,G NSPM 假设 n 阶化学反应、L/S 比的影响和浸出溶液的非理想行为。选择用盐酸浸出死烧菱镁矿来验证所提出的数学模型,因为 HCl 的(表观)反应级数 n 可能为正也可能为负,具体取决于 HCl 浓度。模拟与实验的比较表明,S NSPM 并未反映正负 n 下的性质不同的浸出行为,尤其是在接近化学计量的 HCl/MgO 比时。G NSPM 不仅定性地反映了 n 的影响,但也具有可接受的准确性。在化学计量的 HCl/MgO 比率下,使用 S NSPM 获得的预测的均方误差为 100-130 rel。% 与 G NSPM 提供的数据相比。通过数值模拟详细研究了反应级数、n、L/S 比(由降低的 HCl/MgO 摩尔比 ϕ 表示)和酸的非理想行为的共同影响。参数 n 和 ϕ 的值可以定性地改变浸出行为。相比之下,HCl 的活度系数只会略微改变动力学曲线的形状,但不会改变整体情况。使用 S NSPM 计算的 MgO 完全转化时间误差可达 100 rel 以上。% n = − 0.5 甚至高达数百 rel。n = 1 时的 %,因为转换与
更新日期:2020-09-01
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