摘要:
In order to recover in an environmentally sound and economic manner used hardening shop salts which contain nitrate-nitrite, the salts, comminuted to particle sizes of from 1 to 50 mm, are dissolved in a mixture of nitric acid and hydrogen peroxide without nitrogen oxides arising, and, by evaporation and cooling, potassium nitrate, sodium chloride, and sodium nitrate are obtained sequentially by fractional crystallization.
摘要:
A method for the preparation of a salt mixture useful for hardening steel parts, including of potassium cyanate, potassium carbonate and sodium carbonate, wherein 2.2 to 2.3 moles of urea is first reacted with 1 mole of potassium carbonate to form potassium cyanate. The escaping ammonia is converted with formaldehyde into hexamethylenetetramine. The reaction product, which is potassium cyanate and potassium carbonate, is ground, mixed with powdered sodium carbonate and pressed at between 80.degree. and 230.degree. C. into shaped pieces.
摘要:
In a filter unit (25) and apparatus for desludging salt baths (1), which is flooded at least partially by the salt bath and is in working association with the upper end of a riser tube (23), the bath fluid to be desludged being driven, by means of a compressed air stream, for example, through the riser tube (23) toward the filter unit (9, 25), the filter cloth packet is made of woven wire of a nonferrous metal, preferably an alloy based on aluminum, nickel or titanium, and is surrounded by a filter frame (14), the frame (14) being shaped into a shallow, pyramidal frustum-shaped funnel (18) pointing toward the bottom of the vat, its apical bottom end being provided with a closable opening (19).