Experimental investigation of matte-slag interactions in copper flash smelting

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Journal Title
Journal ISSN
Volume Title
Kemian tekniikan korkeakoulu | Master's thesis
Date
2017-08-29
Department
Major/Subject
European Mineral Engineering Course
Mcode
CHEM 3006
Degree programme
Erasmus Mundus Minerals and Environmental Programme
Language
en
Pages
118+8
Series
Abstract
Much of the studies related to copper flash smelting focuses on the burner and reaction shaft, while settler part of the furnace is not much evaluated. In the settler part, matte and slag separation take place, and it is critical in determining the final matte grade. In this thesis, a novel experimental procedure is employed to evaluate the time-dependent behavior of matte during settling process. Copper concentrate and synthetic slag mixture of known SiO2/Fe ratio was contacted at 1300oC in air atmosphere and inert Argon atmosphere. The ratio corresponded to the actual fluxing ratio of an industrial flash smelting furnace (SiO2/Fe 0.7 – 1.0). The experiments were carried out at several different reaction times, and subsequently analyzed with SEM-EDS to see the progression of matte-slag interactions and reactions. Additional experiments were also conducted by introducing 5-10 mm sized crushed printed circuit boards (PCB) to the mixture. These additional experiments provide initial analysis regarding how the minor metals in the PCB behave in copper smelting. A comprehensive and detailed information about the sequential steps leading to the matte settling from the slag are described in the present work. It was found that oxygen mass transport in slag is the limiting factor of the overall reaction rate. Separation and settling of matte ceased after 10 minutes, while continuous feeding of air leads to total loss of matte to the slag phase after just 5 minutes, with Cu content in the matte reaching peak level after 2-3 minutes. Precious metals in the PCB mostly distributed to the matte to create a Cu-Fe alloy phase distributed rather randomly within the matte. The novel procedure employed in the present work is generally sufficient to qualitatively elaborate the matte-slag separation process, but not quantitatively.
Description
Supervisor
Jokilaakso, Ari
Thesis advisor
Hellsten, Niko
Naakka, Ville
Keywords
matte settling, time-dependent behaviour, PCB smelting, matte separation
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