Abstract
One of the stages of extracting gold and platinum from sulfide materials and circulating slags is the melting stage in ore-thermal and electric furnaces, where the melt is separated into matte and slag. Gold, platinum, and non-ferrous metals are concentrated in the matte. However, a significant portion of them ends up in the slag, which reduces recovery and increases environmental pollution. The main reason for their transition to slag is the flotation of sulfide droplets by gas bubbles, a significant proportion of which occurs during the decomposition of sulfides. Gold and platinum are associated with matte droplets during flotation. Evaluation of adhesion showed that it is large and comparable to the cohesion of these metals. One of the options to reduce the loss of valuable components is to add fluxes to the slag. The influence of calcite and fluorite on the distribution of gold and platinum over the melting products of copper–nickel sulfide materials (matte and slag) has been experimentally studied based on the above theoretical concepts of droplet flotation. When calcite was added to sulfide ore, there was a significant decrease in the sulfur content in the slag (more than 3 times). This, in turn, led to a decrease in non-ferrous metals in the slag by 2–3 times, with gold from 0.45 to 0.29 g/t and platinum from 2.15 to 2.06 g/t. The addition of fluorite to the mixture of copper–nickel matte and model slag (CaO/SiO2/Al2O3 = 40/40/20) significantly reduced the sulfur content and non-ferrous metals by 1.5 times, whereas gold was not found in the slag. The decrease in the number of sulfides in the slag is mainly because the listed additives reduce its viscosity. This leads to acceleration of the coagulation of sulfide drops, which are inevitably carried into the slag during flotation, and increases the rate of their settling to the slag–matte boundary, where they merge with the matte mass.
Highlights
IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
Platinum, and non-ferrous metals are concentrated in matte, but a significant part of them ends up in the slag, which leads to metal losses [1,2]
One of the probable options for the transition of non-ferrous and noble metals into slag is, as our studies show, the flotation of matte droplets containing them with gas bubbles
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The extraction of gold and platinum from sulfide materials is a multi-stage process, including the melting of the prepared concentrate in ore-thermal furnaces. There is when the melt is separated into sulfide and oxide components (matte and slag). Platinum, and non-ferrous metals are concentrated in matte, but a significant part of them ends up in the slag, which leads to metal losses [1,2]. Losses occur during depletion smelting in electric furnaces of converter slag and slag of suspended smelting furnaces
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