Sparge for a high-pressure vessel

A process for operation of a high pressure autoclave for extracting valuable minerals from mineral bearing particles suspended in a slurry in a reaction chamber having a plurality of high energy agitators and at least one sparge associated with each agitator, each sparge comprising a pipe with its free end disposable within the slurry and a vapor lock means located about the free end of the pipe, the vapor lock means comprising a downwardly disposed outlet whose cross-sectional flow area is larger than the cross-sectional flow area of the free end of the pipe, and less than 5% of the area swept by the corresponding agitator, and, wherein the cross-sectional area of the path of the flow of fluid (the “fluid flow path”) through the pipe and the vapor lock means increases in the direction of flow of the reagent fluids, the process comprising the steps of:

• substantially filling the reaction chamber with liquid and the mineral bearing particles;
• heating the slurry to an elevated temperature and pressurizing the reaction chamber to an elevated pressure, to reduce reaction times and to control process parameters for extracting the valuable minerals;
• mixing the liquid and the particles with the agitators to agitate the slurry;
• injecting reagent fluids into the reaction chamber, proximate the agitators, with the sparges, the flow of reagent fluids being downward into the slurry through the outlet;
• dispersing the reagent fluids into the slurry with the agitators and reducing the rate of flow of the reagent fluids inside the pipe towards the outlet in the direction of said flow by making the cross-sectional flow area of the outlet larger than the cross-sectional flow area of the pipe;
• and
• inhibiting backflow of the slurry into the vapor lock means, during conditions of low or no flow of the reagent fluid through said pipe, by making the cross-sectional flow area of the outlet less than 5% of the area swept by the corresponding agitator.