Mechanical caustic soda

Two classes of resol are generally distinguished, water-soluble resins prepared using caustic soda as catalyst, and spirit-soluble resins which are catalysed by addition of ammonia. The water-soluble resins are usually only partially dehydrated during manufacture to give an aqueous resin solution with a solids content of about 70%. The solution viscosity can critically affect the success in a given application. Water-soluble resols are used mainly for mechanical grade paper and cloth laminates and in decorative laminates. 

Selective removal of the less noble constituent has been demonstrated by chemical analysis in the case of nickel-rich alloys in fused caustic soda or fused fluorides ", and by etching effects and X-ray microanalysis for Fe-18Cr-8Ni steels in fused alkali chlorides. This type of excessive damage can occur with quite small total amounts of corrosion, and in this sense its effect on the mechanical properties of the alloy is comparable with the notorious effect of intercrystalline disintegration in the stainless steels. 

An indirect method to determine reaeration in gravity sewers was developed by Parkhurst and Pomeroy (1972). They made the measurements in gravity sewers where the biofilm was removed mechanically followed by a shock load with caustic soda. During the measurement period, the biological activity was suppressed in the water phase by a chemical substance. Measurement of upstream and downstream DO concentrations in the sewer determined the reaeration by using a simple DO mass balance. 

Kostina, G. M. and Chernyak, A. S., 1979. Investigation of the mechanism of electrochemical oxidation of arsenopyrite and pyrite in caustic soda solution. Zhumal Prikladnoi Khimii, 52 1532- 1535... 

Boring of Corks.—Sharp borers should always be used. The end of the cork is placed against some solid object and bored half-way through from one end. The boring should then be completed from the other end. The boring of rubber stoppers may be greatly facilitated by moistening the borer with caustic soda. Mechanical borers are now available. 

The saponification of organotriethoxysilane is carried out in enameled reactor 14 with an agitator and a water vapour jacket. First the reactor is filled from batch box 13 with 42% caustic soda and with a metered amount of water. After the dissolution is complete, the alkali solution receives organotriethoxysilane from batch box 12 at a temperature below 60 °C. The contents of the apparatus are agitated for 1 hour the mixture is sampled to determine the NaOFl content, solid residue and density. The prepared liquid is filtered through brass mesh in nutsch filter 15 into settling box 16. In the settling box the product is separated from mechanical impurities (it is settled for at least 24 hours), filtered in pressure filter 17 and poured into containers. 

Resins for decorative laminates are made by reacting phenol with formaldehyde under alkaline conditions. Normally, reaction would be in a stainless steel vessel fitted with heating jacket, condenser, and mechanical stirrer. The raw materials are reacted with caustic soda under reflux conditions for approximately one hour, after which cooling and discharge take place. The result is a slightly viscous water-soluble resin, brown in colour, which has a considerable shelf-life. 

Exceptions can exist since the corrosion in a wet solution of the interior boiler drum (steel) with dilute caustic soda at high temperature and high pressure and the reaction of high temperature water with aluminum and zirconium have been found to be best interpreted in terms of a dry corrosion mechanism.1... 

In a 6-1. wide-mouth bottle, packed in a pail with a freezing mixture of ice and salt and fitted with a mechanical stirrer, a thermometer and a separatory funnel, are placed 305 g. (5 moles) of nitromethane (Org. Syn. 3, 83) 530 g. (5 moles) of benzalde-hyde (Note 1) and 1000 cc. of methyl alcohol. A solution of sodium hydroxide is prepared by dissolving 210 g. (5.25 moles) of caustic soda in approximately an equal volume of water and cooling. It is then diluted to 500 cc. with-ice and water, poured into the funnel, and added with stirring to the nitromethane mixture at such a rate that the temperature is kept at 10-15° (Notes 2 and 3). 

In the Kraft recovery process the green liquor, which is an aqueous solution of sodium carbonate, is heated with lime to produce white liquor or caustic soda, which is then returned to the pulp digestion operations. In the production of alumina, lime and soda are fed to bauxite digesters. The CaCO 3 produced during the course of the reaction is rebumed to lime and is recycled. The main difficulties associated with these processes include the extensive mechanical handling through the use of causticizers, settlers, and repulpers in order to produce caustic that is low in carbonate and the high fuel consumption needed to reconvert CaCO to lime. 

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