Molybdenum oxide prodn. from molybdenum sulphide concentrate - by oxidn. in aq. slurry, with recirculation for higher yield and recovery of metallic impurities

摘要

Mo oxide (MoO3) (I) prodn. by oxidn. of Mo sulphide (MoS2) concentrates (II) contg. metallic impurities (III) involves converting (II) to an aq. slurry and oxidising this in an autoclave at elevated temp. and elevated O2 partial pressure filtering off (I), neutralising the first filtrate contg. H2SO4 and filtering again. The novel feature is that a high (I) yield is obtd. and (III) are recovered by the use of the following stages: (1) Recirculation of unfiltered oxidised slurry to the slurry prepn. stage until the H2SO4) concn. reaches 80-120 (100)g/l, before filtering off (I). (2) Recirculation fo the first filtrate after neutralisation to pH 0.9-1.5(0.9) with chalk, the CaSO4 formed being filtered off to give a second filtrate (IV), and continuing until (III) are sufficiently enriched in (IV). (3) Neutralisation of (IV) to pH 2.5 with alkali hydroxide and then treating to recover Fe molybdate (V) and (III). The Mo yield is 90-100%, whilst the recovery of (III) e.g. Re and Cu, has environmental and economic advantages.