Apparatus and process for purifying highly impure calcium hydroxide and for producing high-value precipitated calcium carbonate and other calcium products
AssigneeJames W. Bunger and Associates, Inc.
InventorsJames W. Bunger, Don Cogswell, Jerald W. Wiser
Life of this patent
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Abstract
A solution process for the purification of calcium hydroxide, particularly from hydrated carbide lime, which is subsequently used as a feed stock for a high-value calcium product, preferably calcium carbonate. Precipitated calcium carbonate is formed by reaction of the purified calcium hydroxide solution with carbon dioxide in a plug-flow reaction system.
Claims32
A method for forming precipitated calcium carbonate comprising dissolving impure hydrated lime into an aqueous solution,
- separating solid materials from the dissolved hydrated lime to form a clear solution of calcium hydroxide,
- reacting the clear solution with carbon dioxide gas in cocurrent plug-flow reaction conditions to form a suspension of precipitated calcium carbonate.
A method for controlling the reaction environment in a continuous reaction of calcium hydroxide and carbon dioxide to form calcium carbonate comprising;
- directing a solution of calcium hydroxide free of solid-phase calcium hydroxide into a reaction zone,
- directing carbon dioxide-containing gas into the reaction zone,
- reacting essentially all of the calcium hydroxide in the solution with the carbon dioxide gas to form calcium carbonate by mixing the solution and the gas in the reaction zone to form a suspension of precipitated calcium carbonate while directing the solution and the gas together along an axis in the reaction zone in cocurrent plug-flow conditions.
A method for controlling the reaction environment in a continuous reaction of calcium hydroxide and a reagent to form a calcium product comprising;
- directing a solution of calcium hydroxide free of solid-phase calcium hydroxide into a reaction zone,
- directing the reagent into the reaction zone,
- reacting essentially all of the calcium hydroxide in the solution with the reagent to form calcium product by mixing the solution and the reagent in the reaction zone to form a suspension of precipitated calcium product while directing the solution and the reagent together along an axis in the reaction zone in cocurrent plug-flow conditions,
- the calcium product having a solubility in the solution less than the solubility of calcium hydroxide.
Dependencies are inferred from the claim text.