Centrifuging Step-Screw Conveyor for Regolith

A variety of ISRU operations will utilize lunar regolith as feedstock. The proposed centrifuging step-screw conveyor concept will provide a well controlled robust, reliable, dust-free method of transporting loose regolith over short distances (up to 10's of meters) at any inclination angle, ranging from vertical-up to vertical-down. The method offers immediate variable flow-rate control, including complete reversal of the direction of the solids flow without changing the rotation rate of the conveyor drive. This novel approach for transporting loose granular solids can provide a reliable means of moving regolith from a lower to an upper hopper – a stated NASA need for oxygen production from regolith. This SBIR project will demonstrate the feasibility of the basic variable-flow-rate centrifuging step-screw. Planned follow-on Phase-2 development will optimize the shape of the step-screw blades to minimize wear and power requirements and couple the basic step-screw with a reliable pre-screening method to reject material greater than 5mm in size. The unit could be sized for Oxygen production scale operations (50kg/hr) or for construction-scale operations (300kg/hr). This conveying technology has very low frictional losses compared to conventional screw conveyors. The basic modular design allows any number of individual modules to be Daisy-chained together, with arbitrary, abrupt, changes in angle from zero to 180o at each module transition. Each succeeding leg can go at any arbitrary direction or inclination, even vertically up or down, always maintaining precise, adjustable solids flow control. Centrifuging step-screw conveyors could be used in any solids-transport situation where conventional screw augers, bucket elevators, or short conveyor belts are the current transport means being considered. The potential advantages include robust operation, and precise control of solids flow rates with minimal set of moving parts.