Kureha Kagaku Kogyo Kabushiki Kaisha

Kureha Engineering Co., Ltd.

Kiwamu Yamamoto

Isao Funahashi

Koju Suto

The present invention lies in a method of improving a Langelier index and pH of city water wherein undissolved matter (calcium carbonate and slaked lime covered with calcium carbonate) slurry produced in a slaked lime dissolving vessel is mixed and reacted with carbonic acid-containing water in a mixing and reacting vessel to make a calcium hydrogen carbonate aqueous solution so as to continuously add to water in a water-receiving vessel together with a slaked lime aqueous solution, with which a utilization percentage of undissolved matter which has hitherto had a low utilization percentage is increased, and the Langelier index can be improved.

Apparatus for improving city water

A method of producing an aqueous solution of slaked lime is disclosed the steps of: introducing water into a slaked lime-dissolving apparatus comprising a dissolving tank, a water supply piping connected to a lower part of the tank, a stirring blade disposed within the tank in its bottom part, an effluent piping connected to an upper part of the tank for discharging aqueous slaked lime solution, and a fluidized slaked lime layer height-control device disposed within the tank above the stirring blade, subsequently introducing a predetermined amount of slaked lime into the tank, feeding water, with low-speed stirring, to the tank from the water supply piping in such a rate that the water in the cylindrical or rectangular upper part of the tank ascends at a rate of from 0.25 to 1.2 mm/sec, and taking out an aqueous solution of slaked lime from the tank through the effluent piping.

Method of producing aqueous solution of slaked lime and apparatus

The Langelier index and pH of city drinking water are improved by mixing and reacting a slurry of calcium carbonate and slaked lime covered with calcium carbonate produced in a slaked lime dissolving vessel with carbonic acid-containing water in a mixing and reacting vessel to make a calcium hydrogen carbonate aqueous solution which in turn is continuously added to water in a water-receiving vessel together with the aqueous solution of slaked lime. As a result, unused undissolved matter is decreased, and the Langelier index of drinking water can be improved.

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Yokosuka, Japan

Kiwamu Yamamoto