The increase in metals demand in the electrifying globe means significant growth in the smelting
of copper, nickel, zinc, and lead, produced from primary sulfide sources or using sulfide mattes as
the intermediates of the process chains. This means that leaner and complex mineral deposits will
be evaluated as ores and are in the future traded in the commodity market for smelting and refining
to pure metals.
An important issue in the trend is the technology metals, like antimony, tellurium, and gallium, which
exist as trace elements in sulfide ores and form no ores of their own. Their recovery becomes
important in the coming decades as will be the case with growing slag amounts without use in other
industries. The key is to produce environmentally acceptable slags in the smelting operations. It sets
new boundary conditions to the treatment of flue dusts. This means that all material streams of
smelting and refining must be re-evaluated for the deportments of the main and minority metals.
In copper smelting, the recoveries of precious metals are today important for the feasibility of the
custom smelters but due to low prices of many minority metals they are discarded in slag landfills. It
is one of the emerging issues also in the secondary copper smelting today and once the demand
grows, the same question will be faced also in the mining-beneficiation-smelting-refining chain of the
primary production of nickel, zinc, and lead. The distributions of many technology metals in the
copper and nickel smelting have been recently studied using methods where the chemically bound
trace elements in the slag and its phases at the smelting conditions have been studied. Thus, the
key data about options for process modifications and additional processing steps are piling up.
Short processing routes in the metals smelting and refining are attractive due to their simplicity. At
the same time, complexity of many raw materials challenges the fluxing at high oxygen partial
pressures in low silica slags with high metal concentrations. The compromise between high primary
recovery and safe operation is a demanding task in conditions where slag foaming outside the
processing window is evident.
The increase in the demand of pure nickel is challenging the raw material basis where low-grade
sulfide ores are soon smelted along with nickel laterites to matte. It is a demanding task at high MgO
concentrations. The low solubility of MgO in iron silicate slags requires new fluxing strategies and
new smelting end points for the operation at reasonable temperatures; the direct nickel matte
smelting in one-matte mode may be an option.