ABSTRACT

The melting behavior of Platreef and UG–2 platinum group metal (PGM) concentrates was studied under conditions typically found in the black top of PGM smelters. In order to understand how the phase changes influence the separation between matte and slag, the concentrates were characterized before and after firing at eight temperatures from 800°C to 1480°C. The PGM concentrates were isothermally heated in either silica (Platreef) or magnesia crucibles (UG–2), which in turn were sealed in steel capsules under argon atmosphere. This configuration prevented the escape of sulfur–containing gases during the experiments. Observed phase relations were compared against phase relations predicted by FactSage® under oxygen partial pressures in the range of 10^–18 to 10^–9 bar and sulfur partial pressures in the range of 10^–9 to 10^–3.5 bar. The results showed the effective separation of matte from the gangue minerals at sub–liquidus temperatures of the gangue (1480°C for UG–2 concentrate, 1400°C and 1480°C for Platreef concentrate). The PGM concentrates did not sinter at low temperatures (800–1100°C); however, from 1200°C the formation of a liquid phase promoted liquid phase sintering. The collection of matte in a button at the bottom of the crucible was facilitated by the formation of a continuous liquid phase in the sintered concentrate, through which the matte droplets could descend. This occurred after the main gangue phase, enstatite, melted incongruently.

摘要

Platreef 和 UG-2 铂族金属 (PGM) 精矿的熔化行为是在 PGM 冶炼厂黑色顶部的典型条件下研究的。为了了解相变如何影响冰铜和炉渣之间的分离，在 800°C 至 1480°C 的八个温度下烧制前后对精矿进行了表征。PGM 精矿在二氧化硅 (Platreef) 或氧化镁坩埚 (UG-2) 中等温加热，然后在氩气气氛下密封在钢胶囊中。这种配置防止了实验期间含硫气体的逸出。^{将观察到的相位关系与 FactSage® 在 10 –18}至 10 ^–9范围内的氧分压下预测的相位关系进行比较bar 和硫分压范围为 10 ^–9至 10 ^–3.5 bar。结果表明，在脉石的亚液相线温度下（UG-2 精矿为 1480°C，Platreef 精矿为 1400°C 和 1480°C），冰铜与脉石矿物的有效分离。PGM 精矿在低温 (800–1100°C) 下不烧结；然而，从 1200°C 开始，液相的形成促进了液相烧结。通过在烧结精矿中形成连续液相促进了在坩埚底部的按钮中收集锍，锍液滴可以通过该液相下降。这发生在主要脉石相顽火辉石不协调地熔化之后。