Effects of reactor type and mass transfer on the morphology of CuS and ZnS crystals

For the precipitation of CuS and ZnS, the effects of the reactor/precipitator type, mass transfer and process conditions on crystal morphology were studied. Either H2S gas or a S2- solution were applied. Three different types of reactors have been tested, namely a laminar jet, a bubble column and an MSMPR reactor. The choice of reactor type as well as mass transfer and metal concentration all have a considerable influence on the morphology of the produced crystals. A well mixed bubble column with H2S containing gas as feed yields the coarsest crystals. Use is then made of the surface active properties of CuS-particles, which induce agglomeration at the gas-liquid interface, where as the low metal concentrations inside the reactor also contribute to the formation of coarser particles (especially for ZnS).