Abstract: Bacterial contamination is removed from wastewater by a sterilizing process and apparatus (10). A wastewater piping circuit (26, 28, 30, 31, 32, 34) interconnects a supply tank (12), three serial heat exchangers (16, 18, 20), and a storage tank (14). The circuit and storage tank are sanitized by flushing with a mist of hydrogen peroxide (44) and nitrogen (50). One heat exchanger (16) transfers heat from the sterilized wastewater to the unsterilized wastewater. A closed hot process water piping circuit (60, 62, 64) interconnects a hot process water boiler (22) and the other two heat exchangers (18, 20). The wastewater is sterilized in an insulated holding tank (24) interconnecting the other two heat exchangers (18, 20). Wastewater is pumped through the piping and heated by hot process water in the manifold to kill the bacteria, and is covered by a layer of nitrogen (54) in the storage tank (14).

Abstract: Aerobic and anaerobic contamination is removed from a slurry by a sterilizing process and apparatus (10). A slurry piping circuit (26, 28, 30, 32, 34) interconnects a supply tank (12), three serial heat exchangers (16, 18, 20) and a storage tank (14). The circuit and storage tank are sanitized by flushing with mist of hydrogen peroxide (44) and nitrogen (50). One heat exchanger (16) transfers heat from the sterilized slurry to the unsterilized slurry. A closed hot water piping circuit (60, 62, 64) interconnects a hot water boiler (22) and the other two heat exchangers (18, 20). The slurry is sterilized in an insulated manifold (24) interconnecting the other two heat exchangers (18, 20). Slurry is pumped through the piping and heated by hot water in the manifold to kill the bacteria, and is covered by a layer of nitrogen (54) in the storage tank (14).

Abstract: A process for obtaining a sodium hydroxide solution and a slurry of fine calcium carbonate particles suitable for use as a paper coating or filler pigment includes the initial step of reacting a calcium hydroxide with sodium carbonate under conditions effective to produce an aqueous slurry containing sodium hydroxide and calcium carbonate as a precipitate. The aqueous sodium hydroxide solution is then removed from the first slurry by suitable means such as filtration. The slurry is reconstituted, and a fine fraction comprising an aqueous slurry of fine metal carbonate particles is removed from by suitable means such as a classifying device. The second half of the process can be used independently to process mined calcium carbonate.