Particulate material transfer

An apparatus 10 for transferring a particulate material such as sieve 16 from a first container 14 to a second container 26 without exposing the material to the atmosphere. The apparatus 10 comprises a gas circulation pump 12 for drawing gas from the first container 14 thereby to entrain the sieve, a gas/particulate separator in the form of, for example, a cyclone device 22 and a transfer tube 20 for transferring the mixture of gas and entrained material to the separator 22. An inert gas supply is connected to the first container so as to shield the sieve from the atmosphere. In operation, the vacuum acts to suck the sieve along tube 20 and into separator 22 in which sieve material is separated from the gas and passed into the second container 26 which may be a PSA plant. Separated gas and any unseparated particulate material may either be returned to the first container for re-use or directed to a second separator 32 for further separation.