Precious Metal Distributions in Direct Nickel Matte Smelting with Low-Cu Mattes
- PDF / 2,399,836 Bytes
- 15 Pages / 593.972 x 792 pts Page_size
- 6 Downloads / 207 Views
SMELTING of sulfidic raw materials currently represents the majority of nickel production and generates more than 90 pct of pure nickel supply.[1,2] The innovative modification of flash smelting oxidizing the feed mixture into a low-iron nickel matte directly in one step, the DON process, has been in operation now for more than 20 years.[3] It is a low-capex, low-environmental emission technology which produces a furnace matte suitable to nickel refinery operations and a high-iron electric furnace matte ensuring high recoveries of nickel and cobalt.[4] Despite the obvious importance of this smelting technique and the very different operational point, i.e., the primary smelting furnace of the DON process compared to conventional flash smelting[2] or electric furnace technologies,[5] relatively little relevant fundamental data and equilibrium measurements have been made available for
P. PISKUNEN, K. AVARMAA, L. KLEMETTINEN, and P. TASKINEN are with the Department of Chemical and Metallurgical Engineering, School of Chemical Engineering, Aalto University, P.O. Box 16200, 00076 Aalto, Finland. Contact e-mail: pekka.taskinen@aalto.fi H. O’BRIEN is with the Geological Survey of Finland, Betonimiehenkuja 4, 02150 Espoo, Finland. H. JOHTO is with the Boliden Harjavalta, Teollisuuskatu 1, 29800 Harjavalta, Finland. Manuscript submitted May 12, 2017.
METALLURGICAL AND MATERIALS TRANSACTIONS B
the metal value distributions between low-iron nickel mattes and iron silicate slags.[6,7] In matte smelting, a simple silica flux prevents the formation of solid iron oxides if the chemistry of gangue does not require other, more expensive fluxing agents. Due to geological reasons, some nickel sulfide concentrates contain substantial amounts of MgO, which, due to its low solubility in iron silicate slags, modifies the slag produced and its liquidus boundaries.[8,9] The general trend of sulfide smelting involves increased metal dissolution and loss to the slag when the iron concentration of the matte is reduced, by increasing the prevailing oxygen potential (lO2 lO2 =) RT ln[PO2 ] of the system. The strong basic character of MgO dissolved in the slag will also increase the activity coefficients of less basic dissolved oxides in the acidic slag and thus the slag assay in high MgO levels may have an impact on metal recoveries in sulfide smelting. The behavior of cobalt and silver in copper-free nickel-iron mattes at 1573 K (1300 C) was studied by Font et al.[10] in PSO2 = 101 to 1 atm at Mg2SiO4 saturation. Font et al.[11] measured the solubilities of base metals in iron silicate slags in equilibrium with copper-nickel-iron mattes with different NCu/(NCu + NNi) ratios, in high-SO2 atmospheres from PSO2 = 0.1 to 1 atm. However, only the distribution data from Font et al.[12] in MgO saturation will be used here because the earlier papers do not provide results given as a function of iron concentration of nickel matte. Choi and
Cho[13,14] measured the distribution of cobalt between sulfur-rich nickel matte and silica-saturated iron silicate slag at
Data Loading...
