Colloidal grout mixing apparatus and method
AssigneeBritish Nuclear Fuels plc
InventorsJohn Isherwood, Gary Christian, Timothy J. Wearden
Life of this patent
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Abstract
A mixing method uses, and a colloidal grout mixing apparatus comprises, an upright cylindrical vessel in which a mixer is located. The mixer comprises a shaft extending substantially co-axially with the longitudinal axis of the vessel, and a paddle assembly mounted on the shaft. The paddle assembly produces a vortex in liquid in the vessel, and also provides a high shear region near the base of the vessel. A non-shear pump is connected to the base to discharge grout from the vessel. The grout may be discharged to a drum containing radioactive waste and mounted on a vibratory platform.
Claims16
A method of mixing a colloidal grout having a water/solids ratio of 0.5 by weight or less, the method comprising feeding a measured quantity of water into a cylindrical vessel having a base, rotating in the vessel, a paddle means having a shaft aligned substantially coaxially with the longitudinal axis of the vessel and having a plurality of paddle members and a paddle diameter of 35 cm at a relatively fast rotational rate between 380 rpm and 466 rpm, positioning the paddle members between 30 cm and 43 cm above the base of the vessel and the paddle members having a radial dimension relative to the internal radius of the vessel in the ratio of about 7:16 such as to produce a high shear region near the base and a vortex in the water, feeding a measured quantity of grout materials downwardly into the vortex so as to mix the grout materials and the water with a water/solids ratio of 0.5 by weight or less and thereby produce the said colloidal grout, and discharging mixed grout from an outlet port at least near the base of the vessel via non-shear pump means.
A colloidal grout mixing apparatus comprising a cylindrical mixing vessel having a base, an outlet port at least near the base of the vessel, and a non-shear pump means for discharging mixed grout from the outlet port, wherein the improvement comprises a mixing means having two speeds and extending into the vessel, the upper speed being between 380 rpm and 466 rpm, the mixing means including a shaft aligned substantially coaxially with the longitudinal axis of the vessel and a paddle means mounted on the shaft, the paddle means comprising a plurality of paddle members arranged to provide a paddle diameter of 35 cm and each having a shape adapted to cause substantial outward radial displacement therefrom of material being mixed as the shaft rotates, each paddle member being positioned at a height between 30 cm and 43 cm above the base of the vessel and having a radial dimension relative to the internal radius of the vessel in the ratio of about 7:16 such that in operation, at the faster of the two speeds with the paddle means rotating at a rate between 380 rpm and 466 rpm the paddle means produces a vortex in liquid in the vessel and a high shear region near the base, and at the lower of the two speeds maintains a colloidal grout in the vessel mobile.
A colloidal grout mixing apparatus comprising, a cylindrical vessel having a base and having an internal diameter of about 80 cm, an outlet port at least near the base of the vessel, a non-shear pump means connected to the outlet port for discharging mixed grout from the vessel, a shaft aligned substantially coaxially with the longitudinal axis of the vessel, a motor at one end of the shaft and having two speeds, the higher of the two speeds being between 380 and 466 rpm and the lower speed being between 180 and 210 rpm, and a paddle mixer at the other end of the shaft located about 35 cm above the base of the vessel, the paddle mixer having a diameter of about 35 cm and a plurality of flat paddle members which lie in respective longitudinal axial planes with respect to the shaft, load cells adapted to support the vessel so as to monitor the weight of material fed into and discharged from the vessel, a recirculation circuit connected between the pump means and the side of the vessel, a vibratory platform for supporting a container, a valve means, a discharge duct from the pump means and connected to the valve means, and return duct connected at one end to the valve means and at the other end being positioned above the vessel so as to discharge therein, an outlet duct from the valve means extending so as to discharge into the container, and the valve means being controllable so as to discharge grout from the vessel either to the container or back to the vessel.
Dependencies are inferred from the claim text.