CS260471B1 - Process for the treatment of solid residues resulting from the neutralization of extracting trihydrogenphosphoric acid - Google Patents

Abstract

The wet solid residues resulting from the production of alkali metal phosphate salts from trihydrogen phosphoric acid extraction are mixed, after possible reduction of the alkali salt content, with quicklime and/or burnt dolomite and/or burnt magnesite and/or with raw material or raw materials containing anhydrous salt or salts which form hydrates with water, and the resulting mixture is processed into powder or granular form. The resulting 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 hydroxide and / or alkali metal bicarbonate and / or carbonate into a calcium or calcium-magnesium fertilizer.

To date, these residues have not been processed for this purpose even though they contain a considerable amount of phosphorus.

This disadvantage is overcome by the method of treating the solid residues resulting from the neutralization of the phosphoric acid phosphate with hydroxide and / or alkali metal bicarbonate and / or carbonate into a phosphorous-containing calcium or calcium-magnesium fertilizer, which comprises reacting these wet residues, optionally after reducing the content of alkali or alkaline salts by dissolving them into an aqueous medium, preferably at elevated temperatures of up to boiling point, and quicklime and / or burnt dolomite and / or burnt magnesite and / or raw material or raw materials containing anhydrous salt or salts with water they form hydrates in an amount of at least 0.15 mol per 1 mol of water in the residue, and the resulting mixture is processed into a powder and / or granular or granular form.

Preferably, the wet residue is liquefied.

Advantageously, additional nutrients and / or trace elements of importance for plant nutrition and protection and / or soil physicochemical improvers are added.

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

The basic effect of the production method according to the invention is that dry phosphorus-containing fertilizer is produced from wet residues without a drying operation, thereby saving energy costs.

The manufacture may be continuous, discontinuous or a combination of both. For example, wet solid residues after reduction of the alkali salt content by dissolving it in an aqueous medium, preferably at a higher temperature up to the boiling point, are mixed with quicklime in a ratio such that almost all water is bound to form lime hydrate. . As a result of the heat released during the hydration reaction, the mixture is heated and some of the water evaporates. Thus, the amount of lime added may be less than the stoichiometry due to the hydrate formation. During the homogenization of the mixture or during granulation, it is possible to add further nutrient components, substances containing trace elements or improving the physico-chemical properties of the soil or the physical properties of the fertilizer.

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

Example

Washed sodium salts almost free of residue after neutralization of the sodium trihydrogenphosphoric acid to the second stage with a content of about 50% by weight. the waters were mixed with quicklime and homogenized. The lime is used in an amount of 0.65 mol per 1 mol of water contained in the residues. A powdered product was formed.

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

Claims (4)

Process for the treatment of solid residues resulting from the neutralization of an extract of trihydrogenphosphoric acid with hydroxide and / or an alkali metal bicarbonate and / or carbonate, into a phosphorus-containing calcium or calcium-magnesium fertilizer, characterized by reacting these wet residues, optionally after reduction or alkali salts by dissolving them into an aqueous medium, preferably at elevated temperatures of up to boiling point, and quicklime and / or quicklime dolomite and / or quicklime magnesite and / or raw material (s) containing anhydrous salt or salts which form hydrates with water in an amount of at least 0.15 mole per mole of water in the remainder, and the resulting mixture is processed into a powder or / or granular or granular form. 2. The method 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. The process according to claims 1 to 3, characterized in that substances improving the physical properties of the product are added.