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 -SiO₂, FeO _x -SiO₂-Al₂O₃, and FeO _x -SiO₂-Al₂O₃-CaO slag) were investigated at 1300 °C in controlled flowing CO-CO₂-SO₂-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.

The distribution coefficients of Ni, Co, Ag, Au, Pt, and Pd between molten copper and silica-saturated iron silicate slags ( $$ {\text{L}}_{\text{Me}}^{{{\text{Cu}}/{\text{s}}}} $$ L Me Cu / s ) were measured experimentally. The distribution behaviors were studied under typical conditions of copper converting and fire refining, i.e., from 1250 °C to 1350 °C, and from 10⁻⁸ to 10⁻⁴ atm oxygen partial pressure. The coefficients were determined as the ratios of the trace element weight concentrations measured in situ, directly from the equilibrated metal and slag phases. For the quantitative elemental analysis of the phases, state-of-the-art analytic techniques, including electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry, were employed. The distribution coefficients $$ {\text{L}}_{\text{Me}}^{{{\text{Cu}}/{\text{s}}}} $$ L Me Cu / s determined can be arranged in the following order: Pt > Au > Pd >> Ag > (Cu) > Ni > Co > (Fe).

The distributions of Ga, In, Sn, and Te between copper-iron mattes and silica-saturated iron silicate slags over a wide range of matte grades 55 to 75 pct Cu were determined at 1300 °C using a gas-phase equilibration-quenching technique and direct phase composition analysis by Electron Probe X-ray Microanalysis and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry. Alumina from aluminum, a typical minor element of electric and electronic copper scrap, and lime were adopted as slag modifiers for increasing the trace element recoveries. Gallium and tin were distributed predominantly in the slag, indium preferred sulfide matte at low matte grades and slag at high, whereas tellurium strongly favored the sulfide matte in particular in high matte grades. The slag modifiers alumina and lime had a minor impact on the distribution coefficients of gallium and tin, but for indium and tellurium the distribution coefficients were more strongly affected by the basic oxides. The strong tendencies of tin and tellurium to vaporize at the experimental temperature were confirmed.

The distribution equilibria of silver, indium, gallium, and tin between a copper alloy and alumina-containing iron silicate slag have been measured experimentally at 1300°C. In reducing conditions, copper acts as a collector for gallium, but its distribution coefficient between metal and slag is always less than one. Indium will be almost completely oxidized to the slag in high oxygen partial pressures and reduced fully back to the copper alloy in the slag cleaning conditions, around p_O2 ≈ 10⁻¹⁰ atm. The behavior of tin is similar to indium in low oxygen pressures, where copper alloy dissolves most tin from the slag (log₁₀ L^m/s(Sn) ≈ 2). In high oxygen partial pressures, most tin was volatilized from the system, and tin concentrations were below the detection limit (0.02 wt-%), less than 0.005 wt-% in slag and less than 0.002–0.003 wt-% in the alloy. Up to 90% of its initial silver amount in the copper alloy was lost in the gas at p_O2 > 10⁻⁶ atm and its concentration in copper was less than 0.1 wt-% [Ag]. The observations suggest that addition of lime to iron silicate slags with alumina, in reducing conditions below p_O2 ≈ 10⁻⁷ atm at silica saturation, lowers slightly the metal-to-slag distribution coefficients.

In this study, the equilibrium distributions of selected trace elements between molten iron-saturated copper alloy and selected iron silicate slags were measured, and the effects of silica fluxing on them. In addition to the copper and iron main components of the system, trace elements like antimony, gallium, germanium, gold, indium, and silver were added in experiments that spanned the temperature range of 1473–1573 K (1200–1300 °C). Experimental charges were quenched and prepared in polished mounts. In situ analyses of the resulting phases were made directly on the mounts without the need of phase separation prior to analysis. Electron probe X-ray microanalysis was used for concentrations at or above approximately 100 ppmw, and laser ablation-inductively coupled plasma-mass spectrometry for the lower concentrations in the slags. The very low slag concentrations of germanium, antimony, and indium obtained indicate that these elements can be removed from the slag by reduction, whereas gallium concentrations in the slag were high. Consequently, gallium removal from iron residues, such as zinc smelting jarosite, is difficult without volatilization. Based on the present observations, the industrial reduction processes for the treatment of smelting and refining slags as well as for the processing of iron residues, and extracting the reducible metal oxides and their metal values can be optimized. The target in fluxing should be to maintain the slag compositions with a silica concentration higher than about 28 wt%.

The goal of this work is to develop a material model for Norway spruce and Scots pine woods for use in performance-based fire safety design to predict char front progress and heat release in burning timber. For both woods a set of two different models is estimated: one that assumes wood as a single component and another that considers the pyrolysis of wood principal components independently (single and parallel reactions models, respectively). The material models are calibrated using cone calorimeter experiments. The models are intended for a number of different fire scenarios, such as fully developed fire with only little oxygen in the compartment, or the decay period after flaming with exposed char still smoldering. For both spruce and pine, the single and parallel reactions models are able to predict the experiments in the scale of cone calorimeter with near-equal accuracy. Hence, the single reaction model emerges as the preferable level of complexity when modelling charring and heat release, avoiding the increased uncertainty associated with the additional parameters of the parallel reactions model. When scaling up to the simulations of large scale fire tests, the models can predict the char front progress, but the final temperature profile differs from the experimental. The effects of crack forming in the char layer is one of the likely causes, but its mechanisms are not sufficiently known. Therefore, we suggest a closer study on crack formation in wood under fire as future research.