Zinc Plant Expansion and Modification for Increased Metals …
373
Fig. 3 Flowsheet of pure jarosite and roaster feed pre-treatment integrated to the roasting–leaching
circuit
operation of fluid bed roaster and full combustion of the sulphur cake, a homogeneous
feed blend is also required. Pilot test work at Outotec’s R&D center in Frankfurt has
proven that full oxidation can be achieved with blend produced by feed pre-treatment
system and that the calcine quality is not affected by simultaneous oxidation of
sulphur cake and concentrate. Moreover, the dust entrainment to the roaster freeboard
could be reduced significantly compared to roasting of untreated concentrate as it is
practiced nowadays. Based on test result obtained in pilot plant, it was decided to
install the FPS as part of the modification project. In the FPS, the sulphur cake from
the pure jarosite process is blended with Zn concentrates. The new feed pre-treatment
system can proceed the total concentrate feed stream, feeding all three roasters with
51 tph of concentrate (on dry basis). The plant design is based on a mass flow of
5 tph of sulfur cake on dry basis.
FPS designed by Outotec consists of transportation, dosing granulation, feeding,
and discharge of material. It will be possible to operate each of the two parallel
granulators in a flexible range between 50 and 100% of the design capacity, and each
installed system is also able to handle the full capacity of all three roasters. If the
entire FPS section is out of operation for any reason, the full roasting capacity would
be kept by bypassing the zinc concentrate stream around the FPS section.
373
Fig. 3 Flowsheet of pure jarosite and roaster feed pre-treatment integrated to the roasting–leaching
circuit
operation of fluid bed roaster and full combustion of the sulphur cake, a homogeneous
feed blend is also required. Pilot test work at Outotec’s R&D center in Frankfurt has
proven that full oxidation can be achieved with blend produced by feed pre-treatment
system and that the calcine quality is not affected by simultaneous oxidation of
sulphur cake and concentrate. Moreover, the dust entrainment to the roaster freeboard
could be reduced significantly compared to roasting of untreated concentrate as it is
practiced nowadays. Based on test result obtained in pilot plant, it was decided to
install the FPS as part of the modification project. In the FPS, the sulphur cake from
the pure jarosite process is blended with Zn concentrates. The new feed pre-treatment
system can proceed the total concentrate feed stream, feeding all three roasters with
51 tph of concentrate (on dry basis). The plant design is based on a mass flow of
5 tph of sulfur cake on dry basis.
FPS designed by Outotec consists of transportation, dosing granulation, feeding,
and discharge of material. It will be possible to operate each of the two parallel
granulators in a flexible range between 50 and 100% of the design capacity, and each
installed system is also able to handle the full capacity of all three roasters. If the
entire FPS section is out of operation for any reason, the full roasting capacity would
be kept by bypassing the zinc concentrate stream around the FPS section.