Abstract: A method is disclosed for controlling retention time in a reactor, such as an autoclave, having a plurality of compartments separated by dividers with underflow openings. A retention time of the reaction mixture is calculated and compared with an optimal retention time, and the volumes of the reaction mixture in the compartments are adjusted while maintaining the flow rate of the reaction mixture, so as to change the retention time to a value which is closer to the optimal retention time. The reactor may include a level sensor in the last compartment for generating volume data; a control valve for controlling the liquid level in the last compartment; and a controller which receives volume data from the level sensor and controls operation of the control valve.

Abstract: A method and apparatus for controlling a temperature within a reactor vessel such as an autoclave operating at elevated temperature and pressure. The apparatus includes a preheating vessel for preheating a feed material such as an aqueous slurry. The preheating vessel forms part of a preheating control system providing the primary means of temperature control within the reactor vessel. The apparatus also comprises secondary means for heating and cooling the reactor. Feed material temperature is increased or decreased by the preheating control system, based on the reactor temperature. Where the preheating control system is at or near its capacity for heating or cooling, the secondary heating or cooling means is activated to bring the reactor temperature within an optimum range.

Abstract: A method is disclosed for controlling retention time in a reactor, such as an autoclave, having a plurality of compartments separated by dividers with underflow openings. A retention time of the reaction mixture is calculated and compared with an optimal retention time, and the volumes of the reaction mixture in the compartments are adjusted while maintaining the flow rate of the reaction mixture, so as to change the retention time to a value which is closer to the optimal retention time. The reactor may include a level sensor in the last compartment for generating volume data; a control valve for controlling the liquid level in the last compartment; and a controller which receives volume data from the level sensor and controls operation of the control valve.

Abstract: By appropriately designing a flash tube, spraying of abrasive slurry on the vessel walls and impinging the multiphase jet on bottom of the vessel are minimized. By appropriately designing a flash vessel, once the flash tube has been designed, a slurry pool is provided having a volume that is sufficient to dissipate the flash tube exit jet momentum and the mass of entrained carryover products exiting from the vapor outlet is minimized.

Abstract: By appropriately designing a flash tube, spraying of abrasive slurry on the vessel walls and impinging the multiphase jet on bottom of the vessel are minimized. By appropriately designing a flash vessel, once the flash tube has been designed, a slurry pool is provided having a volume that is sufficient to dissipate the flash tube exit jet momentum and the mass of entrained carry-over products exiting from the vapor outlet is minimized.

Abstract: A method and apparatus are disclosed for controlling a temperature within a reactor vessel such as an autoclave operating at elevated temperature and pressure. The apparatus includes a preheating vessel for preheating a feed material such as an aqueous slurry. The preheating vessel forms part of a preheating control system which provides the primary means of temperature control within the reactor vessel, and the reactor temperature is used as the setpoint for the preheating control system. The apparatus also comprises secondary means for heating and cooling the reactor. The feed material temperature is increased or decreased by the preheating control system, based on the reactor temperature. This is sufficient to heat or cool the reactor under most process conditions. Where the preheating control system is at or near its capacity for heating or cooling, the secondary heating or cooling means is activated to bring the reactor temperature within an optimum range.

Abstract: The temperature of a metallurgical slurry in a heater vessel is accurately controlled by heating a first portion of the slurry in the heater vessel by contact with a heating medium such as steam, and by adding to the heater vessel controlled portions of a slurry at lower temperature. The lower temperature slurry may be added to the heater vessel in an intermittent or continuous manner, with addition of the lower temperature slurry being regulated by a valve, the operation of which is controlled by a control device which receives temperature information from one or more temperature sensors.