The present invention is a process, a method, and system for recovery and concentration of dissolved ammonium bicarbonate from a wastewater containing ammonia (NH3) using gas separation, condensation, filtration, and crystallization, each at controlled operating temperatures. The present invention includes 1) removal of ammonia from waste (sludges, semi-solids, and solids and liquids) without the use of chemicals at a temperature of at least 80 degrees Celsius, 2) mixing of the gaseous ammonia with carbon dioxide and water vapor and concentrating dissolved ammonium carbonate and ammonium bicarbonate using reverse osmosis at a temperature of between about 35 and 50 degrees Celsius, and 3) crystallizing concentrated dissolved ammonium carbonate and ammonium bicarbonate at a temperature of less than about 35 degrees Celsius to form solid ammonium bicarbonate and ammonium carbonate.

The invention relates to a process for preparing synthetic calcium fluoride (CaF.sub.2) (min 90% CaF.sub.2 by weight) from fluosilicic acid, comprising the following steps: (a) reacting fluosilicic acid (H.sub.2SiF.sub.6) with ammonium hydroxide or ammonia in a first reactor so as to obtain a first slurry; filtering said first slurry so as to obtain a filtrate containing a solution of ammonium fluoride; (b) precipitating the solution of ammonium fluoride obtained as a filtrate in step (a) with calcium carbonate as a dry form or as a suspension at a concentration ranging from 10 to 80% by weight in a second reactor so as to produce a second slurry containing calcium fluoride and ammonium carbonate; filtering said second slurry so as to obtain a filter cake containing calcium fluoride and a filtrate containing a solution of ammonium carbonate; washing and drying said filter cake so as to obtain calcium fluoride and a filter cake washing containing a solution of ammonium carbonate; wherein a portion of the second slurry ranging from 10 to 70% is recycled to the second reactor (3) so as to enhance calcium fluoride crystallization; (c) evolving the major part of ammonia from the second reactor (3) in step (b) because of the partial decomposition of ammonium carbonate under reactor conditions and then scrubbing and returning said ammonia to the first reactor, and gathering and treating by distillation and condensation both ammonium carbonate solutions obtained as the filtrate and the filter cake washing in step (b) to recover liquid ammonia which is recycled to the first reactor (1).

The invention relates to a process for preparing synthetic calcium fluoride (CaF.sub.2) (min 90% CaF.sub.2 by weight) from fluosilicic acid, comprising the following steps: (a) reacting fluosilicic acid (H.sub.2SiF.sub.6) with ammonium hydroxide or ammonia in a first reactor so as to obtain a first slurry; filtering said first slurry so as to obtain a filtrate containing a solution of ammonium fluoride; (b) precipitating the solution of ammonium fluoride obtained as a filtrate in step (a) with calcium carbonate as a dry form or as a suspension at a concentration ranging from 10 to 80% by weight in a second reactor so as to produce a second slurry containing calcium fluoride and ammonium carbonate; filtering said second slurry so as to obtain a filter cake containing calcium fluoride and a filtrate containing a solution of ammonium carbonate; washing and drying said filter cake so as to obtain calcium fluoride and a filter cake washing containing a solution of ammonium carbonate; wherein a portion of the second slurry ranging from 10 to 70% is recycled to the second reactor (3) so as to enhance calcium fluoride crystallization; (c) evolving the major part of ammonia from the second reactor (3) in step (b) because of the partial decomposition of ammonium carbonate under reactor conditions and then scrubbing and returning said ammonia to the first reactor, and gathering and treating by distillation and condensation both ammonium carbonate solutions obtained as the filtrate and the filter cake washing in step (b) to recover liquid ammonia which is recycled to the first reactor (1).

The present invention is a process, a method, and system for recovery and concentration of dissolved ammonium bicarbonate from a wastewater containing ammonia (NH3) using gas separation, condensation, and crystallization, each at controlled operating temperatures. The present invention includes 1) removal of ammonia from waste (sludges, semi-solids, and solids and liquids) without the use of chemicals at a temperature of at least 80 degrees Celsius, 2) condensing the gaseous containing ammonia, carbon dioxide and water vapor to remove water vapor concentrating the amount of gaseous ammonia and carbon dioxide, 3) concentrating the ammonia and carbon dioxide in the water by established means, such as concentrating the gas using partial condensation followed by passing the concentrated gas through an absorption column at a temperature of between about 20 and 50 degrees Celsius to form dissolved ammonium carbonate and ammonium bicarbonate, or total condensation followed by dewatering using reverse osmosis, and 4) crystallizing concentrated dissolved ammonium carbonate and ammonium bicarbonate at a temperature of less than about 35 degrees Celsius to form solid ammonium bicarbonate and ammonium carbonate.

The present invention is a process, a method, and system for recovery and concentration of dissolved ammonium bicarbonate from a wastewater containing ammonia (NH3) using gas separation, condensation, and crystallization, each at controlled operating temperatures. The present invention includes 1) removal of ammonia from waste (sludges, semi-solids, and solids and liquids) without the use of chemicals at a temperature of at least 80 degrees Celsius, 2) condensing the gaseous containing ammonia, carbon dioxide and water vapor to remove water vapor concentrating the amount of gaseous ammonia and carbon dioxide, 3) concentrating the ammonia and carbon dioxide in the water by established means, such as concentrating the gas using partial condensation followed by passing the concentrated gas through an absorption column at a temperature of between about 20 and 50 degrees Celsius to form dissolved ammonium carbonate and ammonium bicarbonate, or total condensation followed by dewatering using reverse osmosis, and 4) crystallizing concentrated dissolved ammonium carbonate and ammonium bicarbonate at a temperature of less than about 35 degrees Celsius to form solid ammonium bicarbonate and ammonium carbonate.

The invention relates to a process for recovering ammonia from an initial aqueous mixture comprising ammonium ions and ammonium salts, the process comprising providing an initial aqueous mixture, desorbing ammonia using humid, heated air to obtain a desorbing liquid phase and a desorbing gas phase, separating the desorbing liquid phase, mixing the desorbing gas phase with a capture gas to obtain a gas mixture, and condensing the gas mixture to obtain a condensate comprising ammonium ions and salt, and an outlet gas. The desorbing liquid phase comprises ammonium ions and ammonium salts in a total concentration of less than 100 ppm. The capture gas comprises carbon dioxide in an amount of at least 50,000 ppm. The total concentration of ammonium ions and ammonium salts in the condensate is higher than the total concentration in the initial aqueous mixture. The invention further relates to a system for performing an ammonium recovery process, a composting system, a composting process and a system for composting and recovering ammonia.

The present invention pertains to new methods for generating energy and useful nitrogen compounds from captured carbon dioxide. It involves employing an osmotic engine, draw solution, and feed solution. An osmotic gradient between the solutions assists in generating energy and a solution of ammonium carbonate, ammonium bicarbonate or mixture thereof. This solution may be decomposed to form ammonia, carbon dioxide, a precipitate, or a mixture thereof.

The present invention pertains to new methods for generating energy and useful nitrogen compounds from captured carbon dioxide. It involves employing an osmotic engine, draw solution, and feed solution. An osmotic gradient between the solutions assists in generating energy and a solution of ammonium carbonate, ammonium bicarbonate or mixture thereof. This solution may be decomposed to form ammonia, carbon dioxide, a precipitate, or a mixture thereof.

The present invention pertains to new methods for generating energy and useful nitrogen compounds from captured carbon dioxide. It involves employing an osmotic engine, draw solution, and feed solution. An osmotic gradient between the solutions assists in generating energy and a solution of ammonium carbonate, ammonium bicarbonate or mixture thereof. This solution may be decomposed to form ammonia, carbon dioxide, a precipitate, or a mixture thereof.

The present invention pertains to new methods for generating energy and useful nitrogen compounds from captured carbon dioxide. It involves employing an osmotic engine, draw solution, and feed solution. An osmotic gradient between the solutions assists in generating energy and a solution of ammonium carbonate, ammonium bicarbonate or mixture thereof. This solution may be decomposed to form ammonia, carbon dioxide, a precipitate, or a mixture thereof.