WO2024059123A1 - Fertiliser product - Google Patents

Abstract

A borate fertiliser product comprising a fast release source of boron and a slow release source of boron, with the slow release boron source comprising ulexite.

Description

FERTILISER PRODUCT

CROSS REFERENCE TO RELATED APPLICATION

This Application claims priority to United States Provisional Patent Application No. 63/406,698 filed on September 14, 2022.

TECHNICAL FIELD

The present disclosure relates to a fertiliser product.

The present disclosure relates particularly, although by no means exclusively, to a boron-containing, i.e. borate, fertiliser product.

The present disclosure relates particularly, although by no means exclusively, to a boron-containing fertiliser product comprising a fast release source of boron and a slow release source of boron.

The present disclosure also relates to a process and a plant for producing a boron- containing fertiliser product.

BACKGROUND

Fertilisers are used to supplement the amount of essential macronutrients in soil, for example nitrogen, potassium, phosphorous, sulphur, calcium and magnesium.

Other elements that are needed in much smaller amounts for plant growth are called micronutrients, such as boron, zinc, manganese, iron, copper, molybdenum and chlorine.

A borate fertiliser is a fertiliser containing boron in a water soluble form.

Boron can be applied to plants in several ways. One option is as sodium borate (i.e. borax - sodium tetraborate).

Borate fertiliser products that are currently available can be divided into two types, namely:

1) Fast release: refined borate fertilizers that have higher solubility in water, are released immediately on application, and are readily available for plant uptake.

2) Slow release: mostly unrefined or minimally refined borate ores with low water solubility like ulexite and colemanite which break down slowly in soil and are not released immediately after application. They release boron over longer period after application. The disclosure is concerned with providing a borate fertiliser product comprising a fast release source of boron and a slow release source of boron.

It is understood that the above description is not to be taken as an admission of the common general knowledge anywhere.

SUMMARY OF THE DISCLOSURE

The present disclosure provides a boron-containing fertiliser product.

The disclosure is a borate fertiliser product comprising a fast release source of boron and a slow release source of boron, with the slow release boron source comprising or consisting of ulexite.

In general terms, ulexite is a hydrated borate of sodium and calcium.

Ulexite (for example having a chemical formula Na2O.2CaO.5B2O3.16H2O) is a major sodium/boron mineral. It is a soft mineral consisting of a hydrous borate of sodium and calcium and usually occurs in loose masses of white fibers.

The applicant has found that the combination of ulexite (as a slow release boron source) and a fast release boron source ensures effective, sustained continued release of boron to plants over an extended period.

The fast release boron source provides boron to plants immediately upon application while the slow release boron source breaks down slowly and provides continued supply of boron during and after the fast release boron source has been consumed. This is a value added product.

The ratios of the slow release boron source and the fast release boron source may be selected as required having regard to a required boron release profile and total % boron for a targeted application.

The ulexite:fast boron source ratio may be in a range of 5:95-95:5, typically 10:90- 90: 10, and more typically 20:80-80:20.

The ulexite may be in any suitable form.

The fast release boron source may be any suitable fast release boron source or combination of fast release boron sources in any suitable form.

The fast release boron source may be any one or more than one of boric acid (H3BO3), disodium octaborate tetrahydrate (DOT - Na2BsOi3 AEEO), anhydrous borax (TSfeE^O?), anhydrous boric acid, kernite (Na2B4O? 4H2O), tincal (Na2B4O?.10H2O), sodium tetraborate pentahydrate (Na2B4O?.5H2O), and potassium borate (B4K2O7) (with the potassium acting as a macronutrient).

Zinc borate ^CEZm) (with the zinc acting as a micronutrient) may be used to modulate the release property of the fertiliser product. Zinc borate is typically considered to have low solubility in water and consequently a “slow release” boron source. It follows that applying zinc borate to the fertiliser product for example as a coating agent can slow the release property of a fertiliser product containing a large amount of “fast release” boron source material. Corresponding, zinc borate can increase the release property of a fertiliser product containing a large amount of boron source material such as ulexite which have slower release properties.

The fertiliser product may comprise materials in addition to the fast release source of boron and ulexite.

For example, the fertiliser product may comprise a micronutrient in addition to boron.

The additional micronutrient may be any suitable micronutrient such as zinc.

The zinc may be in a form of zinc acetate, zinc fluoride, zinc bromide, zinc nitrate, zinc chloride, zinc iodide, zinc oxide, zinc permanganate, zinc sulfate heptahydrate, zinc sulfate monohydrate, zinc sulfite, zinc tartrate, zinc oxysulfate, zinc EDTA, and zinc ammonia salts.

The additional micronutrient may be any one of the following micronutrients in the following forms:

1) Micronutrient iron: iron (II) carbonate, iron (II) nitrate, iron (II) chloride, iron (II) hydroxide, iron (II) oxalate, iron (II) sulfate, iron (III) chloride, iron (III) fluoride, iron (III) hydroxide, iron (III) nitrate, iron (III) sulfate, iron EDTA.

2) Micronutrient manganese: manganese (II) bromide, manganese (II) carbonate, manganese (II) chloride, manganese (II) hydroxide, manganese (II) nitrate, manganese (II) fluoride, manganese (II) oxalate, manganese (II) sulfate, manganese oxy-sulfate, manganese EDTA.

3) Micronutrient copper (not commonly needed): copper (I) chloride, copper (I) hydroxide, copper (I) iodide, copper (I) sulfide, copper (I) oxide, copper (II) fluoride, copper (II) bromide, copper (II) carbonate, copper (II) chloride, copper (II) hydroxide, copper (II) nitrate, copper (II) oxide, copper oxalate, copper (II) sulfate, copper (II) sulfide, copper EDTA.

4) Micronutrient molybdenum: ammonium molybdate, molybdenum tri oxide, molybdenum disulfide, calcium molybdate, magnesium molybdate. 5) Micronutrient nickel: nickel sulfate, nickel bromide, nickel carbonate, nickel chloride, nickel fluoride, nickel formate, nickel hydroxide, nickel iodide, nickel nitrate, nickel oxalate, nickel sulfate.

6) Micronutrient cobalt (not commonly needed): cobalt (II) fluorosilicate, cobalt (II) iodide, cobalt (II) nitrate, cobalt (II) nitrite, cobalt (II) oxalate, cobalt (II) sulfate, cobalt (II) chloride, cobalt (II) bromide, cobalt (II) fluoride.

The fertiliser product may comprise a macronutrient.

The macronutrient may be any suitable macronutrient such as potassium.

The additional macronutrient may be any one of the following macronutrients in the following forms:

1) Macronutrient phosphorous: super phosphate, concentrated super phosphate, mono-ammonium phosphate, di-ammonium phosphate, ammonium polyphosphate, phosphoric acid, phosphorous acid, phosphonic acids, bone ash, bone meal, rock phosphates.

2) Macronutrient magnesium: magnesium acetate, magnesium bromide, magnesium carbonate, magnesium chloride, magnesium formate, magnesium hydroxide, magnesium fluoride, magnesium iodide, magnesium nitrate, magnesium oxalate, magnesium oxide, magnesium phosphate, magnesium sulfate, magnesium sulfite, magnesium thiosulfate, magnesium selenite, magnesium selenite.

3) Macronutrient calcium: calcium acetate, calcium benzoate, calcium bicarbonate, calcium bromide, calcium carbonate, calcium fluoride, calcium chloride, calcium citrate, monocalcium phosphate, calcium formate, di-calcium phosphate, calcium hydroxide, calcium iodide, calcium nitrate, calcium nitrite, calcium oxalate, calcium oxide, calcium phosphate, calcium selenite, calcium sulfate.

While the disclosure extends to the above micronutrient and macronutrient additions, boron is the main active fertiliser component of the fertiliser product.

The amount of boron in the fertiliser product may be any suitable percentage of the active fertiliser components of the fertiliser product.

Typically, boron is at least 90 wt.%, and more typically at least 95 wt.%, of the active fertiliser components of the fertiliser product. In one example, boron ranges from 10-20 wt.%, preferably 15 wt.%. In this example, the B2O3 content ranges from 40-50 wt.%, preferably 47 wt.%.

The fertiliser product may comprise an organic acid, such as a citric acid or an oxalic acid, for improving the release of boron from the slow release boron source such as ulexite in the fertiliser product by slow acidic hydrolysis. The organic acid may act as a pH modifying agent or a chelating agent.

It is an important consideration in the agricultural fertiliser industry that fertiliser products contain minimum amounts of materials that provide no fertiliser benefit (e.g. starch binders). Therefore, typically, the formulated fertiliser product contains minimal amounts of such other materials.

The borate fertiliser product may be in any suitable form.

Typically, the borate fertiliser product may be in the form of granules.

The term “granules” is understood herein to mean medium-sized particles, for example having have an irregular shape, formed by compacting together or agglomerating together or otherwise forming together smaller-sized particles.

After being formed, the granules may be crushed.

The granules may be any suitable size.

Typically, the granules are 1-5 mm in size, more typically 2-4 mm in size.

The borate fertiliser product, typically being in the form of compacted granules of 2 to 4 mm in granule size or granules of 1-5 mm in granule size, is suitable for use as a controlled release fertilizer, general fertilizer, or crops nutrient, in soil applications.

The granules may be formed by agglomeration or compaction. In one example, the granules are formed by agglomeration including a mixing step that involves mixing material having a total moisture content of greater than 20 wt.%, suitably greater than 30 wt.%. In another example, the granules are formed by agglomeration including a mixing step that involves mixing material having a total moisture content of less than 30 wt.%, suitably less than 20 wt.%.

The granules may have any suitable physical and chemical properties (hardness, solubility, particle size distribution).

Typically, the physical and chemical properties are similar to known ulexite granular fertiliser products.

The fertiliser product may comprise granules and a coating of a control release agent to control release of boron to plants.

The coating may be made from any suitable material.

The coating may be made from a sulphur-containing material.

The coating may be made from a sulphur-containing polymeric material.

The coating may include any one of the following materials: Inorganic materials: bentonite, phosphogypsum, gypsum, hydroxy apatite, zeolites, sepiolite.

Synthetic polymers: polyurethane, polyethylene, polyacrylamide, polycaprolactone, polystyrene, polysulfone, aliphatic polyester, polyvinyl alcohol, bio-based epoxy.

- Natural polymers: starch, cellulose, chitosan, ethyl cellulose, carboxymethyl cellulose, hydroxy methyl cellulose, hydroxypropyl methylcellulose, bio-based polyurethane, polysulfone, latex, natural rubber, lignin, alginate.

- Hydrophobic sealants: paraffin, polyols.

The coating may be formed by any one of the following coating techniques: rotary drum, pan, fluidized bed, melting and extrusion, solution polymerization and crosslinking, inverse suspension polymerization, and microwave irradiation.

The sulfur-containing coating on borate fertiliser product granules may assist sustained release of boron to plants due to the low water/soil dissolution of sulfur.

In addition, sulfur-coated borate granules may also assist in lowering the pH of acidic soils.

The fertiliser product may comprise a binder.

The binder may be any suitable material.

The binder may be a starch.

The binder may be water.

The fertiliser product may comprise a slow release boron source in addition to ulexite.

According to the present disclosure, there is also provided a process for producing a fertiliser product comprising:

(a) blending together, for example by dry mixing or wet mixing, a fast release source of boron and a slow release source of boron, with the slow release boron source comprising ulexite, and forming a blend; and

(b) compacting or agglomerating or otherwise forming the blend into granules.

When blending step (a) comprises wet mixing the fast release source of boron and the slow release source of boron, the process may include agglomerating the blend to form granules. Suitably, blending step (a) includes drying the agglomerated granules.

When blending step (a) comprises dry mixing the fast release source of boron and the slow release source of boron, the process may include compacting the blend to form granules.

The fast release boron source may be any one or more than one of boric acid (H3BO3), disodium octaborate tetrahydrate (DOT - Na2BsOi3 4H2O), anhydrous borax (TSfeB^?), anhydrous boric acid, kernite (Na2B4O? 4H2O), tincal (Na2B4O?.10H2O), sodium tetraborate pentahydrate (Na2B4O?.5H2O), and potassium borate (B4K2O7) (with the potassium being a macronutrient).

Blending step (a) may comprise mixing an organic acid, such as a citric acid or an oxalic acid with the other components of the blend.

Blending step (a) may comprise mixing a binder with the other components of the blend.

The binder may be a starch.

The binder may be water.

Blending step (a) may be a bulk blending step in which the ulexite and the fast release source of boron and any other components of the blend are added together at the same time and then mixed together.

Blending step (a) may comprise any suitable sequence of adding and mixing the ulexite and the fast release source of boron and any other components of the blend.

The process may comprise forming coatings of a control release agent to control release of boron to plants on the granules.

The process may comprise crushing the granules.

The process may comprise classifying, for example screening, the granules and separating the granules on the basis of size and producing a product fraction.

The process may comprise classifying, for example by screening, the granules into an oversize fraction, a product fraction, and an undersize fraction.

The product fraction may be any suitable size fraction.

The product fraction may be at least 1 mm.

The product fraction may be at least 2 mm.

The product fraction may be no more than 6 mm.

The product fraction may be no more than 5 mm.

The product fraction may be no more than 4 mm.

The product fraction may be a 1-4 mm size fraction.

The product fraction may be a 1-6 mm size fraction.

The process may comprise a crushing step for the oversize fraction.

Suitably, the process comprises returning crushed oversize fraction to the blending step (a).

Suitably, the process comprises returning crushed oversize fraction and undersize fraction to the blending step (a). The process may comprise returning the undersize fraction to the blending step (a).

The process may comprise drying the product fraction to form the fertiliser product.

The present disclosure also provides a plant for producing a fertiliser product that comprises a fast release source of boron and a slow release source of boron, with the slow release boron source comprising ulexite, the plant comprising:

(a) a blending unit for blending together a fast release source of boron and a slow release source of boron, with the slow release boron source comprising ulexite, and forming a blend,

(b) a compaction unit or an agglomeration unit or other unit for forming the blend into granules,

(c) a screening unit for screening the granules and producing a product fraction; and

(d) drying the granules in the product fraction and forming the fertiliser product.

The plant may comprise a coating unit for forming coatings of a control release agent to control release of boron to plants on the granules.

The screening unit may be configured for screening the granules and producing an oversize fraction, the product fraction, and an undersize fraction.

The plant may comprise a crushing unit for crushing the oversize fraction.

The plant may be configured for returning the crushed oversize fraction to the blending unit.

The plant may be configured for returning the undersize fraction to the blending unit.

DESCRIPTION OF EMBODIMENT

The applicant has developed a borate fertiliser product comprising a fast release source of boron and a slow release source of boron, with the slow release boron source comprising ulexite.

The fast release boron source may be any one or more than one of boric acid (H3BO3), disodium octaborate tetrahydrate (DOT - Na2BsOi3 4H2O), anhydrous borax (Na2B4O?), anhydrous boric acid, kernite (Na2B4O? 4H2O), tincal (Na2B4O?.10H2O), sodium tetraborate pentahydrate (Na2B4O?.5H2O, and potassium borate (B4K2O7) (with the potassium being a macronutrient).

The ratios of the different boron sources can be selected appropriately to suit boron release profile and total % boron as required for the targeted application. The fertiliser product may also comprise other components, such as any one or more than one of:

(a) another micronutrient(s) in addition to boron, with the other micronutrient(s) being selected by way of example from zinc and the above list of micronutrients,

(b) a macronutrient such as potassium or any other macronutrient selected by way of example from the above list of macronutrients,

(c) an organic acid, such as a citric acid or an oxalic acid, as a pH modifying agent for improving the release of boron from ulexite in the fertiliser product by slow acidic hydrolysis, and

(d) a binder.

While the disclosure extends to the above micronutrient and macronutrient additions, boron is the main active fertiliser component of the fertiliser product.

The above fertiliser product formulation provides continued sustained release of borates to plants depending on the demand of boron.

The formulation typically is in a granular form to help optimize boron availability to plants.

The amounts of the water soluble fast release boron source(s) may be equivalent to up to 10 mol, typically equivalent to up to 5 mol.

The fast release boron source(s) provide an initial supply of boron due to the quicker dissolution in water/soil, while ulexite would ensure continued sustained supply of boron to plants owing to its slower release profile.

The release profile of ulexite can also be modified to ensure continued availability of boron to plants by mixing ulexite with an appropriate amount of acid.

The acid could be an organic acid such as citric or oxalic acid that slowly hydrolyse ulexite owing to their low pH thus modifying their release kinetics.

The release profile of ulexite can also be modified to ensure continued availability of boron to plants by mixing ulexite with an appropriate amount of inorganic acids like hydrochloric, nitric, sulfuric or phosphoric acids that slowly hydrolyze ulexite owing to their low pH thus modifying their release kinetics.

Typically, the fertiliser product is in the form of granules of 2 to 4 mm in size with a coating of a sulphur-containing material as a release control agent to control release of boron to plants.

Sulfur, owing to its lower solubility in water would prevent complete dissolution of water soluble borates immediately in soil. The release of boron would be possible only with slow break down of the sulfur coating and subsequent controlled dissolution of water soluble borates. This would ensure continued release of boron to plants in crops over longer periods of time. In addition, sulfur-coated borate granules may also assist in lowering the pH of acidic soils.

The fertiliser product may be manufactured by:

(a) bulk blending together, for example by dry mixing or wet mixing, a fast release source of boron and a slow release source of boron, with the slow release boron source comprising ulexite, and any other components mentioned above as may be required, in appropriate ratios; and

(b) compacting or agglomerating or otherwise forming the blend into granules.

When blending step (a) comprises wet mixing the fast release source of boron, the slow release source of boron, and any other components mentioned above, the process may include agglomerating the blend to form granules. Suitably, step (a) includes drying the agglomerated granules.

When blending step (a) comprises dry mixing the fast release source of boron and the slow release source of boron, the process may include compacting the blend to form granules. The ulexite may be obtained from any suitable source.

By way of example, ulexite may be mined and then upgraded to separate clays and other gangue by any one or more of mechanical dispersion, ultrasonic wave treatment, water absorption, and magnetic separation options.

Typically, the blend is compacted and dried in a compaction unit, thereby forming granules.

Typically, the blend is agglomerated in an agglomeration unit and forms granules and the granules are dried or allowed to dry.

The target size of the granules in the final fertiliser product is 2-4mm.

Typically the granules are transferred to a screen unit and separated in an oversize fraction, and undersize fraction, and a product fraction.

The undersize fraction is returned to the compaction unit and re-processed.

The oversize fraction is returned to the crusher unit and re-crushed.

The product fraction, which are target size granules, is transferred to a dryer unit and dried to form the final fertiliser product.

The applicant has conducted bench scale trials with a laboratory scale magnetic separator (1-3 kg) and operating with prototype batch production using a pilot scale magnetic separator to produce an ulexite fraction containing -7.8% B.

The ulexite fraction was combined with 5 mol. of a fast release boron source(s), namely boric acid, DOT, anhydrous borax, anhydrous boric acid, kernite, potassium borate or any combination of the above thereof at appropriate ratios and compacted to form granules at an external toll site.

The test work indicated that, for a given setting of the magnetic separator, the efficiency of separation is independent of the feed quality. The feed quality affects only the yield.

Many modifications may be made to the embodiments described above without departing from the spirit and scope of the invention.

By way of example, whilst the above described fertiliser product comprises ulexite as the slow release boron source, the disclosure extends to fertiliser products that comprise other slow release boron sources in addition to ulexite.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

1. A borate fertiliser product comprising a fast release source of boron and a slow release source of boron, with the slow release boron source comprising ulexite.

2. The fertiliser product defined in claim 1 wherein the fast release boron source comprises any one or more than one of boric acid (H3BO3), disodium octaborate tetrahydrate (DOT - Na2BsO 13 AH2O), anhydrous borax (Na2B4O?), anhydrous boric acid, kernite

H2O), tincal (Na2B4O?.10H2O), sodium tetraborate pentahydrate (Na2B4O?.5H2O), and potassium borate (B4K2O7).

3. The fertiliser product defined in claim 1 or claim 2 comprises a micronutrient in addition to boron.

4. The fertiliser product defined in any one of the preceding claims comprises a macronutrient.

5. The fertiliser product defined in any one of the preceding claims comprises an organic acid for improving the release of boron from ulexite in the fertiliser product.

6. The fertiliser product defined in any one of the preceding claims being in the form of granules.

7. The fertiliser product defined in any one of the preceding claims being in the form of granules with a coating to control release of boron to plants.

8. The fertiliser product defined in claim 7 wherein the coating comprises a sulphur- containing material for assisting sustained release of boron to plants due to the low water/soil dissolution of sulfur.

9. A process for producing a fertiliser product comprising:

(a) blending together, for example by dry mixing, a fast release source of boron and a slow release source of boron, with the slow release boron source comprising ulexite, and forming a blend; and

(b) compacting or agglomerating or otherwise forming the blend into granules.

10. The process defined in claim 9 wherein the fast release boron source comprises any one or more than one of boric acid (H3BO3), disodium octaborate tetrahydrate (DOT -

Na2BsO 13 4H2O), anhydrous borax (Na2B4O?), anhydrous boric acid, kernite (Na2B4O? 4H2O), tincal (Na2B4O?.10H2O), sodium tetraborate pentahydrate (Na2B4O?.5H2O), and potassium borate (B4K2O7).

11. The process defined in claim 9 or claim 10 comprises classifying the granules and separating the granules on the basis of size and producing an oversize fraction, a product fraction, and an undersize fraction.

12. The process defined in claim 10 comprise crushing the oversize fraction and returning the crushed oversize fraction to the blending step.

13. The process defined in claim 11 comprises returning the undersize fraction to the blending step (a).

14. A plant for producing a fertiliser product that comprises a fast release source of boron and a slow release source of boron, with the slow release boron source comprising ulexite, the plant comprising:

(a) a blending unit for blending together a fast release source of boron and a slow release source of boron, with the slow release boron source comprising ulexite, and forming a blend,

(b) a compaction unit or an agglomeration unit or any other unit for forming the blend into granules,

(c) a screening unit for screening the granules and producing a product fraction; and

(d) a drying unit for drying the granules in the product fraction and forming the fertiliser product.