Abstract

Platinum group metals (PGMs) are considered critical raw materials, thus their recycling and re-use is of outmost importance. Among the PGMs, platinum (Pt), palladium (Pd) and rhodium (Rh) are the basic metals used in catalytic converters. Concerning the stringent EU standards for emission control imposed to car manufacturers (Euro 6d nowadays), the worldwide demand for PGMs is being increased. As for PGM recovery methods, research is focusing on greener, plain recovery techniques, which utilize milder reagents and offer energy efficiency. In this work, a state-of-the-art hydrometallurgical process is proposed resulting in recovery rates for Pt, Pd and Rh, namely 100%, 92% and around 60%, respectively. A batch of more than 20 commercial spent catalyst samples has been mechanically pre-processed (i.e. sorted, decanned, milled, grinded, homogenized and characterized), in order for a 20 kg sample of homogenized fine pent catalytic powder to be derived. The proposed hydrometallurgical method does not involve any kind of thermal pre-treatment or chemical reduction, thus energy consumption is minimized, while the use of chemicals has been restricted to simple and cheap inorganic solvents (namely HCl, NaCl and H₂O₂). The aforementioned recovery rates have been validated through X-ray fluorescence spectroscopy analysis (XRF). The equipment used has been successfully calibrated to measure low PGM concentrations (less than 50 ppm for each metal). The kinetics of the hydrometallurgical process have also been studied, in short intervals, and spent catalyst material has been characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy analysis (EDS) and X-ray powder diffraction (XRD).

Graphical Abstract

中文翻译：

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商业废车催化剂中铂族金属浸出的单步湿法冶金方法

摘要

铂族金属（PGM）被认为是至关重要的原材料，因此其回收和再利用至关重要。在PGM中，铂（Pt），钯（Pd）和铑（Rh）是催化转化器中使用的基本金属。关于对汽车制造商实施的严格的欧盟排放控制标准（当今为6d），全球对PGM的需求正在增加。至于PGM的回收方法，研究集中在更绿色，更简单的回收技术上，该技术利用较温和的试剂并提供能源效率。在这项工作中，提出了一种最新的湿法冶金工艺，导致Pt，Pd和Rh的回收率分别为100％，92％和60％左右。已对一批20多种商业用过的催化剂样品进行了机械预处理（即分选，de析，研磨，研磨，均质化和表征），以便获得20千克均质细五氧化碳催化粉末样品。拟议的湿法冶金方法不涉及任何形式的热处理或化学还原，因此可将能耗降至最低，而化学品的使用仅限于简单廉价的无机溶剂（即HCl，NaCl和H₂ O ₂）。前述回收率已经通过X射线荧光光谱分析（XRF）验证。使用的设备已成功校准，以测量低的PGM浓度（每种金属的含量均低于50 ppm）。还已在短时间内研究了湿法冶金过程的动力学，并通过扫描电子显微镜（SEM），能量色散X射线光谱分析（EDS）和X射线粉末衍射（XRD）对废催化剂材料进行了表征。 。

图形概要