The present invention relates to the control of flow of a particulate feed to a reactor, and in particular provides a process for providing a slurry of particulate matter to a reactor, comprising providing a slurry comprising said particulate matter and diluent, and passing said slurry to the inlet of a reactor feed pump from where it is then pumped to the reactor, characterized in that a stream of additional diluent is also passed to the inlet of the reactor feed pump, the reactor feed pump is operated at an essentially constant volumetric flow rate, and the amount of particulate matter in slurry passed into the reactor is adjusted by adjusting the flow.