Method for preparing phosphate compounds
The invention relates to phosphate compounds obtained according to a method comprising reaction of a source of insoluble phosphate with an organic source, principally of vegetable origin, optionally in the presence of a mineral acid or an organic acid, said organic source having at least 10% of complexing functional groups. The compounds of the invention are useful for preparing fertilizer.
1. A method for preparing phosphate compounds comprising the steps of:
a) activating raw organic matter selected from the group consisting of lignite, leonardite, peat, plant composts, lignosulfonates not containing monovalent cations, and algae, wherein the activation is carried out by reacting:
(i) from about 70 wt % to about 98 wt % of an organic or inorganic acid, with
(ii) from about 2 wt % to about 30 wt % of said raw organic matter, such that at least 10% of complexing functional groups present in the raw organic matter are freed, and
b) reacting:
(i) from about 30 wt % to about 50 wt % of a source of insoluble phosphate, with
(ii) from about 50 wt % to about 70 wt % of the activated raw organic matter obtained in step a).
2. The method of claim 1 , wherein the raw organic matter is selected from the group consisting of peat, leonardite, lignite and plant composts.
3. The method of claim 2 , wherein the raw organic matter is peat.
4. The method of claim 1 , wherein the complexing functional groups present in the raw organic matter are selected from the group consisting of carboxyl groups, phenol groups and hydroxyl groups.
5. The method of claim 1 , wherein the inorganic acid is selected from the group consisting of sulphuric acid, phosphoric acid, nitric acid hydrochloric acid and mixtures thereof.
6. The method of claim 5 , wherein the inorganic acid is sulphuric acid, phosphoric acid or a mixture thereof.
7. The method of claim 1 , wherein the organic acid is selected from the group consisting of citric acid, oxalic acid, acetic acid, maleic acid, malonic acid, succinic acid, malic acid, fumaric acid, tartaric acid, pyruvic acid, oxaloacetic acid, ketogluconic acid, butyric acid, propanoic acid and mixtures thereof.
8. The method of claim 7 , wherein the organic acid is oxalic acid, citric acid or a mixture thereof.
9. The method of claim 1 , wherein the source of insoluble phosphate is selected from the group consisting of phosphate rocks, byproducts of animal origin, and byproducts formed during synthesis of polyphosphates.
10. The method of claim 9 , wherein the source of insoluble phosphate consists of phosphate rocks.
11. A method for preparing phosphate compounds comprising the steps of reacting:
(i) from about 40 wt % to about 60 wt % of phosphate rocks,
(ii) from about 30 wt % to about 60 wt % of an organic or inorganic acid, and
(iii) from about 0.2 wt % to about 10 wt % of organic compounds extracted from lignite, leonardite, peat, plant composts, lignosulfonates containing monovalent cations and algae, wherein said organic compounds comprise at least 10% of free complexing functional groups.
12. The method of claim 11 , wherein the complexing functional groups present in the organic compounds are selected from the group consisting of carboxyl groups, phenol groups and hydroxyl groups.
13. The method of claim 11 , wherein the inorganic acid is selected from the group consisting of sulphuric acid, phosphoric acid, nitric acid hydrochloric acid and mixtures thereof.
14. The method of claim 13 , wherein the inorganic acid is sulphuric acid, phosphoric acid or a mixture thereof.
15. The method of claim 11 , wherein the organic acid is selected from the group consisting of citric acid, oxalic acid, acetic acid, maleic acid, malonic acid, succinic acid, malic acid, fumaric acid, tartaric acid, pyruvic acid, oxaloacetic acid, ketogluconic acid, butyric acid, propanoic acid and mixtures thereof.
16. The method of claim 15 , wherein the organic acid is oxalic acid, citric acid or a mixture thereof.