the apparatus allows mixing of a solid and a fluid continuously to facilitate downhole operations , especially gravel packing . the apparatus comprises a solids hopper , with preferably an internal auger , to meter the solids flowrate . the solids drop into a second feeder which empties into a mixing chamber . liquid can be directed into an annular space formed in the mixing chamber around the periphery of the second auger , or could be piped into the second auger itself . a triplex pump is connected to the mixing chamber and draws the mixed solid and fluid and pumps it to sufficient pressures for use in a wellbore .