Method for improved distillation of ammonia from weak ammonia liquor
First Claim
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1. An improved method of distilling weak ammonia liquor containing both free and fixed ammonia derived from a coal coking operation with decreased fouling of the still apparatus comprising:
- (a) premixing ammonia liquor which contains both substantial free ammonia as ammonium carbonate, ammonium sulfide and ammonium cyanide and fixed ammonia as ammonium chloride, ammonium thiocyanate and ammonium sulfate prior to initiating any distillation with sufficient lime to pre-precipitate at least most of the principal components of precipitation fouling from the undistilled weak ammonia liquor, and(b) passing the ammonia liquor subsequent to pre-precipitation with said lime through an ammonia still countercurrently with steam to distill the ammonia liquor and release ammonia from the liquor.
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Abstract
Fouling of an ammonia still, used for removal of ammonia from weak ammonia liquor derived from a coal coking operation, is alleviated by pre-precipitating insoluble calcium salts from the ammonia liquor by treatment of the liquor with lime prior to introduction into a single-leg still.
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Citations
18 Claims
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1. An improved method of distilling weak ammonia liquor containing both free and fixed ammonia derived from a coal coking operation with decreased fouling of the still apparatus comprising:
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(a) premixing ammonia liquor which contains both substantial free ammonia as ammonium carbonate, ammonium sulfide and ammonium cyanide and fixed ammonia as ammonium chloride, ammonium thiocyanate and ammonium sulfate prior to initiating any distillation with sufficient lime to pre-precipitate at least most of the principal components of precipitation fouling from the undistilled weak ammonia liquor, and (b) passing the ammonia liquor subsequent to pre-precipitation with said lime through an ammonia still countercurrently with steam to distill the ammonia liquor and release ammonia from the liquor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 18)
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8. An improved method of distilling weak ammonia liquor derived from a coal coking operation to remove both free and fixed ammonia from the liquor with minimal precipitation fouling of the still apparatus comprising:
- (a) premixing the ammonia liquor which contains both free and fixed ammonia in the form of the free ammonia compounds ammonium carbonate, ammonium sulfide and ammonium cyanide and in the form of fixed ammonia compounds ammonium chloride, ammonium thiocyanate and ammonium sulfate prior to initiating any distillation with a calcium ion containing material to pre-precipitate calcium components of precipitation fouling from the undistilled weak ammonia liquor, sufficient calcium material being added to the liquor to free substantial fixed ammonia in addition to pre-precipitating calcium components of precipitation fouling, and
(b) passing the pre-precipitated ammonia liquor subsequent to premixing with the calcium ion containing material through an ammonia distillation operation countercurrently with steam to distill the ammonia liquor and expel ammonia from the liquor. - View Dependent Claims (9, 10, 11, 12, 13)
- (a) premixing the ammonia liquor which contains both free and fixed ammonia in the form of the free ammonia compounds ammonium carbonate, ammonium sulfide and ammonium cyanide and in the form of fixed ammonia compounds ammonium chloride, ammonium thiocyanate and ammonium sulfate prior to initiating any distillation with a calcium ion containing material to pre-precipitate calcium components of precipitation fouling from the undistilled weak ammonia liquor, sufficient calcium material being added to the liquor to free substantial fixed ammonia in addition to pre-precipitating calcium components of precipitation fouling, and
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14. A method of alleviating deleterious fouling of a still column with solid calcium compounds during distillation of weak ammonia liquor containing both free and fixed ammonia and including in particular carbonates and fluorides derived from a coal coking operation comprising:
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(a) premixing the weak ammonia liquor which contains both substantial free ammonia as the compounds ammonium carbonate, ammonium sulfide and ammonium cyanide and fixed ammonia as the compounds ammonium chloride, ammonium thiocyanate and ammonium sulfate prior to initiating any distillation with sufficient lime to pre-precipitatable calcium fluoride and calcium carbonate and reduce the fluoride ion concentration in the weak ammonia liquor to a point where no substantial calcium fluoride salts will precipitate during distllation, and (b) passing the weak ammonia liquor subsequent to said pre-precipitation through an ammonia distillation operation counter-currently with steam to distill the ammonia liquor and expel ammonia from the liquor. - View Dependent Claims (15, 16, 17)
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Specification