CS260470B1 - Process for the treatment of solid residues resulting from the neutralization of extraction phosphoric acid - Google Patents

Abstract

The wet solid residues resulting from the neutralization of the extraction trihydrogenphosphoric acid with ammonia and/or ammonium hydroxide are mixed with quicklime and/or burnt dolomite and the resulting mixture is processed into a powder or granular form. The ammonia released from the ammonium salts contained in the solid residue can be used, for example, to neutralize the extraction trihydrogenphosphoric acid. The resulting alkaline calcium fertilizer containing phosphorus is suitable for application in acidic soils.

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for the treatment of solid residues resulting from the neutralization of extraction phosphoric acid with ammonia and / or ammonium hydroxide into a calcium or calcium-magnesium fertilizer.

In the production of pure ammonium salts from the trihydrogenphosphoric acid extraction solid water-insoluble residue is eliminated. These residues are not processed so that the phosphorus they contain is not recovered.

This disadvantage is overcome by the treatment of the solid residues resulting from the neutralization of the phosphoric acid phosphoric acid with ammonia and / or ammonium hydroxide to a phosphorus-containing calcium or calcium-magnesium fertilizer, which comprises reacting these wet residues, optionally after reducing the ammonium or ammonium salt content. by dissolving it into an aqueous medium, and quicklime and / or quicklime dolomite in an amount of at least 0.3 mol per 1 mol of water in the residue, and the resulting mixture is processed into a powdered and / or granular or granulated form. Extraction of trihydrogenphosphoric acid.

The wet residue is preferably liquefied.

Advantageously, other nutrients and / or trace elements of importance for plant nutrition and protection and / or substances improving the physical and chemical properties of the soil are added.

Advantages are added to improve the physical properties of the product.

The basic effect of the process according to the invention is to utilize phosphorus which is present in the solid residues which are lost in the production of pure ammonium phosphate salts from the trihydrogenphosphoric acid extraction plant for plant nutrition.

The manufacture may be continuous, discontinuous or a combination of both. For example, the wet solid residues are mixed with quicklime in a ratio such that almost all the water is bound to form a lime hydrate. As a result of the heat released during the hydration reaction, the mixture is heated and some of the water is evaporated. Thus, the amount of lime added may be less than the stoichiometry due to the hydrate formation. The liberating ammonia from the ammonium salts remaining in the solid residue can be used, for example, to neutralize the extractive trihydrogenphosphoric acid. During the homogenization of the mixture or during granulation, it is possible to add further nutrient components, substances containing trace elements or improving the physical-chemical properties of the soil or the physical properties of the fertilizer.

The process according to the invention is described in more detail below with reference to a specific embodiment.

Example

Wet solids after neutralization of the extraction acid with trihydrogenphosphoric acid with ammonia up to pH 5,5 containing approx. the waters were mixed with quicklime and homogenized. Lime was used in an amount of 0.65 mole per mole of water contained in the residues. A powdered product was formed. Ammonia released from the ammonium salts contained in the solid residue was used to neutralize the trihydrogenphosphoric acid extraction acid.

The obtained phosphorus-containing alkaline calcium fertilizer is suitable for application in acidic soils.

Claims (4)

Process for the treatment of solid residues resulting from the neutralization of phosphoric acid phosphoric acid with ammonia and / or ammonium hydroxide to a phosphorus-containing calcium or calcium-magnesium fertilizer, characterized in that the wet residues are reacted, optionally after reduction of the ammonium or ammonium salt content and burnt lime and / or burnt dolomite in an amount of at least 0.3 mol per 1 mol of water in the residue, and the resulting mixture is processed into a powdered and / or granular or granulated form, the resulting ammonia being used to neutralize, for example . 2. A process according to claim 1, characterized in that the wet residue is liquefied. 3. A method according to claim 1 or 2, characterized in that further nutrients and / or trace elements of importance for plant nutrition and protection and / or substances improving the physico-chemical properties of the soil are added. 4. A process according to any one of claims 1 to 3, characterized in that substances improving the physical properties of the product are added.