Recovery of Precious Metals (Au, Ag, Pt, and Pd) from Urban Mining Through Copper Smelting

Abstract

With the aim of investigating deportments of precious metals in pyrometallurgical processing of waste electrical and electronic equipment, the distributions of selected precious metals (gold, silver, platinum, and palladium) between copper matte and three different silica-saturated slags (pure FeO x -SiO 2 , FeO x -SiO 2 -Al 2 O 3 , and FeO x -SiO 2 -Al 2 O 3 -CaO slag) were investigated at 1300°C in controlled flowing CO-CO 2 -SO 2 -Ar gas atmosphere by a high-temperature isothermal equilibration technique. The phase compositions were analyzed by Electron Probe X-ray Microanalysis and Laser Ablation-High Resolution Inductively Coupled Plasma-Mass Spectrometry. It was shown that the distribution coefficients of gold, platinum, and palladium between matte and slag (L m/s (Me) = [Me] in matte /(Me) in slag ) were very high and increased with increasing matte grade. The distributions to the matte phase were increased by adding basic oxides alumina and lime into the acidic silicate slags. The experimentally measured distribution coefficients L m/s (Me) followed the order of platinum > palladium > gold > silver. The present experimental results can be used for upgrading thermodynamic databases for the complex recycling processes through nonferrous smelting.

Precious Metal Distributions Between Copper Matte and Slag at High $$ P_{{{\text{SO}}_{ 2} }} $$ in WEEE Reprocessing

“…Experiments were conducted in a similar way to our previous studies. [25,27,48,49] A high-temperature equilibration under controlled CO-CO 2 -SO 2 -Ar gas atmospheres followed by quenching in ice-water mixture and direct phase analyses by EPMA and LA-HR ICP-MS (HR-High Resolution) techniques was used to study the distributions of precious metals between copper matte and slag. A schematic image of the laboratory-scale furnace used is shown in Figure 1.…”

“…Table I summarizes the previous publications [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] investigating precious metals distributions in experiments simulating copper smelting conditions. A detailed summary of the available solubility/concentration and matte-slag distribution data at low P SO 2 of 0.1 atm [14][15][16][17][18][19][20] was made in our previous papers, [25][26][27] including the experimental techniques used and their weaknesses. To ensure the achievement of equilibrium and improve the accuracy of the experimentally measured data, a method employing high-temperature isothermal equilibration followed by rapid quenching and direct phase analysis [32,33] was developed and has been widely used for investigating matte-slag equilibria.…”

“…To ensure the achievement of equilibrium and improve the accuracy of the experimentally measured data, a method employing high-temperature isothermal equilibration followed by rapid quenching and direct phase analysis [32,33] was developed and has been widely used for investigating matte-slag equilibria. [34][35][36][37][38][39][40][41][42][43][44] Recently, Electron Probe X-ray Microanalysis (EPMA) and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) analytical techniques were successfully applied to measure the concentrations of precious metals in matte/metal and slag, [21][22][23][24][25][26][27][28][29][30][31] leading to increased accuracy and reliability of the experimental data.…”

“…The distributions of precious metals have been extensively investigated between copper matte and slag at P SO 2 lower than 0.2 atm. [13][14][15][16][25][26][27][28][29][30][31] However, the use of oxygen or oxygen-enriched air as the process gas in modern copper flash smelting produces a smaller amount of off-gas with a high SO 2 concentration (> 50 vol pct). [45,46] The mechanism of matte and slag formation in flash smelting generates SO 2 with partial pressures close to 1 atm.…”

Multi-Criteria Decision Making Approaches Applied to Waste Electrical and Electronic Equipment (WEEE): A Comprehensive Literature Review

“…All this represents a huge wasted potential, even in green and circular economy approaches. In fact, WEEE is a source of important and valuable resources which can be used as secondary materials [ 32 , 33 ]. As reported by [ 11 ], WEEE may contain over 69 elements from the periodic table.…”