The Transportable Moisture Limits, as ,measured by the procedures laid down in The IMCO Code of Safe Practices for Bulk Cargoes, determine the target moisture contents for the concentrates produced at the West Coast Mines of Electrolytic Zinc Company of Australasia Limited at Rosebery. Filtration of these concentrates gives moisture contents considered to be low in comparison with those achieved for similar sulphide concentrates, but which are very close to these Transportable Moisture Limits. The filtering techniques used are outlined and the problems associated with-maintaining concentrate moistures below the required limits, together with the methods used to solve these problems are discussed.