Pump Design and Development for High Shear Grout Mixing Applications

The aim of this project was to design and develop a new pump for the mixing and pumping of grout cement. The initial design consisted of a cantilevered supported pump housing containing a centrifugal mill with a series of plate seals, gaskets, flanges and a single tapered bearing. To date, the initial pump has failed as evident from bearing and seal wear. Extensive research of tbe design features of grout mixing units from various competitors and suppliers was conducted. Based on research undertaken a paddle pump design was developed incorporating dual end support, direct grout feed and improved sealing. Design calculations were used to size the hydraulic motor, the impeller shaft diameter, dynamic loading on bearings and their operational lifetime. The new pump unit, based on testing, delivers a suitable head of pressure for the mixing and shearing of the grout mix, leading to a consistent grout mix product. The performance of the pump was measured both physically and experimentally via the use of an industrial hydraulic power pack, capable of delivering the required power and pressure to enable the pump operate at industrial flow rates. Performance tests consisted of varying the flow rates of the grout material through the pump and measuring pressure head at the outlet. Results of the performance testing indicated that the pump operated to design specifications. The dual bearing system design proved satisfactory, with smooth operation even at higher ranges of industrial flow rates. The mechanical seals, selected for aggressive wear and corrosive environments remained leak proof as required. The new pump design features include a
widened pumping impeller for increased shearing of the grout and gives higher volumetric flow rates. This offers advantages to the end user as it is more efficient, robust, maintainability and lest costly to manufacture. Figure 1. shows the assembled unit of the pump, hydraulic motor, holding tank, and the inlet and outlet ducts.