Gomes Beatriz Lobo Filgueiras de Miranda, Bertoli Alexandre C, Duarte Hélio A
Grupo de Pesquisa em Química Inorgânica Teórica (GPQIT), Departamento de Química, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Minas Gerais 31270-901, Brazil.
J Phys Chem A. 2022 Mar 17;126(10):1660-1665. doi: 10.1021/acs.jpca.1c10555. Epub 2022 Mar 8.
Metal-deficient polysulfides have been argued for a long time to be responsible for the low kinetics of chalcopyrite leaching to extract copper. It has been shown that chalcopyrite surfaces are the source of sulfur that is oxidized to form polysulfides and elemental sulfur. Electronic structure calculations were performed for HS ( = 0, 1, 2 and = 1...20), aiming to understand the effect of the pH on the growing chains and the formation of elemental sulfur. The estimated p of the HS polysulfides converges from 4.2 ( = 3) to 3.4 ( ≥ 8), and the estimated p converges from 7.6 ( = 3) to 4.1 ( ≥ 8). The initial steps of the formation of polysulfide chains are more favored for protonated species. The elemental sulfur formation due to the decomposition of polysulfides to form smaller chains is mostly favored for protonated species with smaller than 12. For larger chains, the decomposition is thermodynamically favored for polysulfides with any degree of protonation. The consequences of these results to the understanding of the mechanism of the chalcopyrite leaching process are discussed with the focus on the pH effect and the formation of elemental sulfur.
长期以来，人们一直认为贫金属多硫化物是黄铜矿浸出提取铜动力学缓慢的原因。研究表明，黄铜矿表面是硫的来源，硫被氧化形成多硫化物和元素硫。对HS（ = 0、1、2且 = 1...20）进行了电子结构计算，旨在了解pH值对生长链和元素硫形成的影响。HS多硫化物的估计p值从4.2（ = 3）收敛到3.4（ ≥ 8），估计p值从7.6（ = 3）收敛到4.1（ ≥ 8）。多硫化物链形成的初始步骤更有利于质子化物种。多硫化物分解形成较小链而导致的元素硫形成大多有利于 小于12的质子化物种。对于较大的链，分解在热力学上有利于任何质子化程度的多硫化物。本文讨论了这些结果对理解黄铜矿浸出过程机理的影响，重点关注pH值效应和元素硫的形成。
