TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The process of preparing the carbonate product comprises: reacting carbon dioxide (CO2) containing gas with ammonia (preferred) and aqueous liquor to give the carbonate product. The process comprises:(1) reacting CO2 containing gas with a first base to give first carbonate product, where the first base and the resulting gas has a reduced CO2 content;(2) reacting the first carbonate product with a second base to give a second carbonate product and regenerate at least a portion of the first base;(3) reacting the second carbonate product with the reagent to form CO2 and an intermediate product; separating at least a portion of the CO2 from the intermediate product in a condensed and relatively concentrated stream;(4) reacting the intermediate product with ammonia to form ammonium carbonate product and to regenerate at least a portion of the second base; and(5) separating at least a portion of the fertilizer from the mixture.Preferred Components: The concentration of the carbon dioxide in the CO2 containing gas is less than 35%. The stream of CO2 formed is a stream of greater than or equal to 70% CO2, especially a gas stream. The base is selected from calcium oxide, calcium hydroxide, stream that contains calcium oxide and/or stream that contains calcium hydroxide; or an organic base, a basic solid sorbent, or any base whose solubility in aqueous phase is negligible. The reagent is nitric acid. The stream of the base includes a second base such as sodium hydroxide, potassium hydroxide or primary, secondary or tertiary amine soluble in aqueous solution. The functional groups of the base are a primary amine, a secondary amine and/or a tertiary amine. The first base is sodium or potassium hydroxide, primary, secondary or tertiary amine soluble in aqueous solution or stream that contains the same.Preferred Components: The second base is particularly calcium oxide, calcium hydroxide, and a stream that contains calcium oxide and/or a stream that contains calcium hydroxide. The carbonate product is calcium carbonate. The intermediate product is calcium nitrate and the fertilizer is ammonium nitrate. EXAMPLE - Calcium carbonate crystals were contacted with an aqueous solution of 50% nitric acid. Bubbles of carbon dioxide were released from the crystals to give a mixture solution of nitric acid and calcium nitrate. The aqueous solution of 60% ammonia was added to the mixture to give calcium hydroxide and a solution of ammonium nitrate.