Abstract: The hydrostatic pressure differential existing in a column of fluent material conveyed through an excavated passage possessing a downward entrance run and upward return run facilitates hydrometallugical processing including metals recovery and treatment of ores. Conveyance of the fluent material through the passage is facilitated by appropriate means including a difference in elevation between the inlet and outlet and/or gaseous expansion applied proximate the bottom of the return run. Cooling of effluent proximate the outlet may be utilized consequent to application of heat during processing as in roasting ore. The passage is excavated through rock fully capable of containing the pressures anticipated and has an interior casing which seals the rock porosity. Iron reinforced concrete is recommended in appropriate wall thicknesses.

Abstract: The hydrostatic pressure differential existing in a column of fluent material conveyed through an excavated passage possessing a downward entrance run and upward return run facilitates hydrometallugical processing including metals recovery and treatment of ores. Conveyance of the fluent material through the passage is facilitated by appropriate means including a difference in elevation between the inlet and outlet and/or gaseous expansion applied proximate the bottom of the return run. Cooling of effluent proximate the outlet may be utilized consequent to application of heat during processing as in roasting ore. The passage is excavated through rock filly capable of containing the pressures anticipated and has an interior casing which seals the rock porosity. Iron reinforced concrete is recommended in appropriate wall thicknesses.