Abstract
Slags containing valuable metals are second sources of metals they contain.
The use of macadamia nutshells as reductant has not been investigated in the slag
recycling industry. The current study investigates the use of raw macadamia nut shells
in the recovery of valuable metals from copper slag. A copper slag, from a water-jacket
furnace; containing copper, cobalt, iron and zinc has been used. Both the slag and raw
macadamia nut shells were crushed and milled for characterization. XRF, XRD and
SEM were used for characterization. The basicity of slag was increased through the
addition of calcite. The slag, flux and nutshells were milled together to homogenise the
feed. A graphite crucible was used as a container and placed in a tube furnace.
Experiments were conducted at 1400oC and carbon monoxide was blown into the
furnace to enhance the reducing atmosphere. The feed was kept at the set temperature
for two hours and the furnace was switched off to slowly cool down to room
temperature. The products were characterised using XRD, XRF and SEM. The results
revealed that it is possible to use the macadamia nutshells in the slag recycling industry
with attention to be paid at the final basicity for a better immiscibility of the final slag
and the metal. A comparison of results obtained when the same slag was reduced using
coke showed that, although the quality of the metal obtained using macadamia nutshells
are not as good as when coke is used, there is great prospect in the future.