Nittetu Chemical Engineering Ltd.

Yoshiaki Kinoshita

Mikio Akune

Hidemasa Tsuruta

Yoshiyuki Imagire

Isao Tanaka

Toshiaki Kurihara

A waste fluid containing nitrogen compounds is combusted in an incinerator having cylindrical primary and secondary combustion chambers connected in series by a venturi throat member. The waste fluid is combusted in the primary combustion chamber at a temperature of at least 1200.degree. C. while injecting air into the primary combustion chamber in a direction tangential to the inner periphery thereof so that the combustion gas forms a vortex pattern therein. The whirling combustion gas containing nitrogen oxides is caused to pass through the venturi throat into which a gas or liquid containing a compound having a nitrogen-hydrogen bond is injected for mixing with the combustion gas and the mixture is combusted in the secondary combustion chamber at a temperature of between 850.degree. and 1150.degree. C. The nitrogen oxides produced in the primary combustion chamber are reduced by reaction with the nitrogen-hydrogen bond-containing compound so that the exhaust gas from the secondary combustion chamber has a low content of nitrogen oxides.

Method for the combustive treatment of waste fluids containing nitrogen

A process for recovering caustic alkali from spent alkali liquor, in which a spent alkali liquor and iron oxide are roasted to obtain a product containing alkali ferrate and the product of roasting is hydrolyzed at a temperature over 110.degree. C. and under pressurized conditions where liquid phase is retained, thereby recovering caustic alkali in the form of an aqueous solution of a concentration higher than approximately 15 wt% containing dissolved iron in an extremely small concentration.

Process for recovering caustic alkali from spent alkali liquor

Disclosed is a method whereby a waste water containing ammonium ions, sulfate ions and organic substances is subjected to combustive disposal subsequent to addition of calcium hydroxide or calcium oxide thereto.

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Hino, Japan

Yoshiaki Kinoshita