GB2571914A

GB2571914A - A process for producing a fertiliser containing boron

Info

Publication number: GB2571914A
Application number: GB1802369.7A
Authority: GB
Inventors: Hayati Igan; Theodorus De Graauw Cornelis
Original assignee: KEMITEL Ltd
Current assignee: KEMITEL Ltd
Priority date: 2018-02-13
Filing date: 2018-02-13
Publication date: 2019-09-18
Also published as: GB201802369D0

Abstract

A process for producing a fertiliser containing boron, wherein the process comprises providing the boron in the form of a solution or a suspension. Preferably the boron solution or suspension is formed in a solvent of water and the boron is produced from one or more of boric acid, sodium tetraborate decahydrate or pentahydrate, disodium octaborate tetrahydrate and/or sodium pentaborate decahydrate. The fertiliser may be in the form of granules and the solution or suspension is applied to the surface of the granules in the form of a coating agent/ In other embodiments, the fertiliser is in the form of a powder and the solution or suspension is added as a binding agent, wherein the fertiliser is then granulated to form fertiliser granules. Also claimed is a fertiliser containing boron wherein it has been produced by the above process.

Description

A PROCESS FOR PRODUCING A FERTILISER CONTAINING BORON

This invention relates to a process for producing a fertiliser and, more especially, this invention relates to a process for producing a fertiliser containing boron.

Fertilisers for plants such as crops are typically produced to contain primary macro-nutrients of nitrogen, a phosphate and a potassium. The fertilisers often also contain secondary macro-nutrients of magnesium, calcium and sulphur.

It is also known to add micro-nutrients to the fertilisers, for example for use for different types of crops which require different types of micro-nutrients. One typically known and used micro-nutrient is boron.

The known fertilisers are typically produced in one of two ways. The first way is to produce the fertilisers in the form of granules, with each granule having all of the required nutrients. Such fertilisers are often known as compounded granule fertilisers. The second way is to produce the fertilisers in the form of granules but with each granule having only one nutrient. Granules with different required nutrients are then simply blended together as may be required by a user. Such fertilisers are often known as blended fertilisers.

For compounded granule fertilisers, boron is usually added as sodium tetraborate pentahydrate or decahydrate powder. The sodium tetraborate powder is usually only added in small quantities. This is because boron is used as a micro-nutrient rather than a primary or secondary nutrient. Depending upon the type of crops, if the boron is added in not more than approximately 0.3 - 1.0% B2O3 by weight, then there will typically be no problem. However, if the boron is added in an amount of more than 0.3 1.00% B2O3 by weight, then a problem may occur if the fertiliser is a compounded granule fertiliser. More specifically, the granulation process used to produce the compounded granules may become unstable, with the result that the required relatively small granules are not obtained and instead large lumps are produced. For this reason, with compounded granule fertilisers, the addition of the boron is limited to not more than 1.0% B2O3 by weight.

With blended fertilisers, separate granules containing boron are simply added to the other required different granules making up the total fertiliser. For example, boron granules may be added to a mixture of other granules comprising first granules containing only nitrogen, second granules containing only a phosphate, and third granules containing only potassium. With blended fertilisers, the granules should advantageously be of the same size to reduce the problem of segregation. Because the boron is added in small quantities, blending of the boron granules with the other granules tends to be somewhat haphazard. A resulting blend of whatever granules is required may often have a non-uniform distribution of the boron granules. The result is that some fields of crops may receive a blended fertiliser with too much boron, and other fields of crops may receive a blended fertiliser with not enough boron.

Irrespective of whether the fertiliser is a compounded granule fertiliser or a blended granule fertiliser, it is generally agreed in the art that the presence of boron in the fertiliser adds value to the fertiliser.

Compounded granule fertilisers and blended granule fertilisers both tend to suffer from three problems. Firstly they suffer from granule degradation, with the granules breaking down into powder and/or dust during transportation and handling. Secondly they suffer from granule caking due to moisture ingress, with the resultant granules sticking together to form large lumps. Thirdly they suffer from segregation of fine particles from coarse particles. This is due to the above mentioned particle degradation into powder or dust.

The above problems may cause some farmers to receive fertilisers which are in the form of a powder or dust, and other farmers to receive fertilisers which are in a form of coarse particles.

It is known to try and prevent the caking by adding an anti-caking agent such for example as vegetable oils or glycerine. The anti-caking agent acts to prevent moisture getting into the fertiliser. The addition of the anti-caking agent represents an additional cost. Also, the anti-caking agent may not be as environmentally friendly as would be desired.

It is an aim of the present invention to reduce the above mentioned problems by enabling the provision of the boron in the fertiliser in a homogeneous way.

Accordingly, in one non-limiting embodiment of the present invention, there is provided a process for producing a fertiliser containing boron, which process comprises providing the boron in the form of a solution or a suspension.

Because the boron is added as a solution or a suspension, the above mentioned problems with compounded granule fertilisers and or blended fertilisers are not encountered.

The process of the present invention may be one in which the fertiliser is in the form of compounded granules, and the solution or suspension is applied to the surface of the granules in the form of a coating agent. Typically, the fertiliser granules are dried after the solution or suspension has been applied. With this process, the solution or suspension is applied as a coating and the coating acts to increase the strength of the granules. Nevertheless, the coating and the total composition of the granules is able to be chosen such that it dissolves at the required speed after distribution to crops. As a result of the coating process, the boron is evenly distributed.

The process may alternatively be one in which only one macro-nutrient granule, for example muriate of potash or potassium nitrate or potassuium sulphate, is coated with the boron solution or suspension followed by drying. The resulting boronated potash granules are then blended with the other macro-nutrients. As a result, the boron will be evenly distributed within the fertiliser in comparison to adding neat boron granules due to the larger quantity of boronated potash granules being blended.

The process may alternatively be one in which the fertiliser is in the form of a powder, the solution or suspension is added to the powder as a binding agent, and the fertiliser with the solution or suspension is granulated to form fertiliser granules. The fertiliser granules are typically dried. The dried fertiliser granules may then be screened to the required granule size. The resulting granules are extremely strong and do not suffer from caking and degradation during storage and handling.

The process may alternatively be one in which only one macro-nutrient, for example muriate of potash or potassium nitrate or potassium sulphate, is granulated with the boron solution or suspension followed by drying and screening. The resulting very strong boronated granules are then blended with the other macro-nutrients. As a result, the boron will be evenly distributed within the fertiliser in comparison to adding neat boron granules due to the larger quantity of boronated potash granules being blended.

In all embodiments of the invention, the granules may be formed in the same way as they are formed in known fertilisers.

In all embodiments of the invention, the boron solution or suspension may be provided from one or more of:

(i) boric acid;

(ii) sodium tetraborate decahydrate or pentahydrate;

(iii) disodium octaborate tetrahydrate; or (iv) sodium pentaborate decahydrate.

The solution or suspension may be a solution or suspension of the boron in a solvent in the form of water. Other solvents may be employed but water is preferred as it will generally be the cheapest available solvent.

Preferably the boron is dissolved or suspended in the water at a temperature above 40°C. Such a temperature helps to avoid the use of too much water.

It is believed that the reason for the improved handling properties when the granules are coated with boron, or increased strength when the fertiliser powder is granulated within the boron solution or suspension, is due to a chemical reaction between the boron and the other primary or secondary macro-nutrients such as potassium, phosphorous, magnesium and sulphur.

The coating and granulation processes used in the present invention both allow the addition of higher quantities of boron in the fertiliser, for example, up to 3% B2O3 by weight homogeneously, which some crops require.

The present invention also extends to a fertiliser containing boron, when produced by the process of the invention.

The fertiliser may contain primary and secondary nutrients. The fertiliser may be a mineral fertiliser.

The invention will now be described with reference to the following Examples:

EXAMPLE 1

1kg of boric acid was mixed with 1kg water at 90°C and ground using a Silverson mixer for 10 minutes to produce a <50pm boric acid suspension containing 28% B2O3 by weight.

71.5g of this boric acid suspension was then sprayed onto 1 kg of a compounded granule fertiliser containing nitrogen, a phosphate and potassium, with the granules being placed in a coating drum. The granules were 2 - 4mm in size. The coated granules were then dried in an oven at 180°C. The resulting granules contained 2% B2O3by weight and had excellent anti-caking properties compared to the original granules when stored in a jar at 80% relative humidity for 30 days.

EXAMPLE 2

1kg of sodium pentaborate decahydrate was mixed with 1kg of water at 90°C and ground using a Silverson mixer for 10 minutes to produce a <50pm sodium pentaborate suspension containing 29.5% B2O3 by weight.

67.5g of this sodium pentaborate decahydrate suspension was then sprayed onto 1kg of granular muriate of potash placed in a coating drum. The granules were 2 - 4mm in size. The coated granules were then dried in an oven at 180°C. The resulting granules contained 2% B2O3 by weight and had excellent anti-caking properties compared to the original granular potash when stored in a jar at 80% relative humidity for 30 days.

EXAMPLE 3

1kg of sodium tetraborate decahydrate was mixed with 2kg of water at 90°C and ground using a Silverson mixer for 20 minutes to produce a <50pm sodium tetraborate decahydrate suspension containing 12.2% B2O3 by weight.

164g of this sodium tetraborate suspension was then sprayed onto 1kg of muriate of potash powder (<100pm in particle size) placed in a pan granulator to produce spherical granules ranging from 2 - 4mm in diameter.

The granules were then dried in an oven at 180°C. The resulting granules contained 2% B2O3 by weight with excellent anti-caking properties and crushing strength greater than 40Newton.

EXAMPLE 4

1kg of boric acid was mixed with 3kg of water at 90°C and ground using a Silverson mixer for 20 minutes to produce a <50pm boric acid suspension containing 14% B2O3 by weight.

143g of this boric acid suspension was then sprayed onto 1kg of muriate of potash powder (<100pm in particle size) placed in a pan granulator to produce spherical granules ranging from 2 - 4mm in diameter. The granules were then dried in an oven at 180°C. The resulting granules contained 2% B2O3 by weight with excellent anti-caking properties and crushing strength greater than 40Newton.

EXAMPLE 5

1kg of disodium octaborate tetrahydrate spray dried powder was mixed with 4kg of water at 20°C and suspended using a Silverson mixer for 10 minutes to produce a <75pm boric acid suspension containing 13.4% B2O3 by weight.

149g of this disodium octaborate tetraborate suspension was then sprayed onto 1kg of potassoium sulphate powder (<100pm in particle size) placed in a pan granulator to produce spherical granules ranging from 2 4mm in diameter. The granules were then dried in an oven at 180°C. The resulting granules contained 2% B2O3 by weight with excellent anti-caking properties and crushing strength greater than 40Newton.

EXAMPLE 6

1kg of sodium pentaborate decahydrate was mixed with 3kg of water at 90°C and ground using a Silverson mixer for 20 minutes to produce a <75pm boric acid suspension containing 14.8% B2O3 by weight.

135g of this sodium pentaborate suspension was then sprayed onto 1kg of potassium nitrate powder (<100pm in particle size) placed in a pan granulator to produce spherical granules ranging from 2 - 4mm in diameter. The granules were then dried in an oven at 180°C. The resulting granules contained 2% B2O3 by weight with excellent anti-caking properties and crushing strength greater than 40Newton.

It is to be appreciated that the embodiments of the invention described above with reference to the Examples has been given for illustrative purposes only and not for the purposes of limitation. Embodiments of the invention described in the Examples may be used in other embodiments, and in all aspects of the invention.

Claims

1. A process for producing a fertiliser containing boron, which process comprises providing the boron in the form of a solution or a suspension.

2. A process according to claim 1 in which the fertiliser is in the form of granules, and the solution or suspension is applied to the surface of the granules in the form of a coating agent.

3. A process according to claim 2 in which the fertiliser granules are dried after the solution or suspension has been applied.

4. A process according to claim 1 in which the fertiliser is in the form of a powder, the solution or suspension is added to the powder as a binding agent, and the fertiliser with the solution or suspension is granulated to form fertiliser granules.

5. A process according to claim 4 in which the fertiliser granules are dried.

6. A process according to claim 5 in which the dried fertiliser granules are screened to the required granule size.

7. A process according to any one of the preceding claims in which the boron solution or suspension is produced from one or more of:

(i) boric acid;

(ii) sodium tetraborate decahydrate or pentahydrate;

(iii) disodium octaborate tetrahydrate; or (iv) sodium pentaborate decahydrate.

8. A process according to any one of the preceding claims in which the solution or suspension is a solution or suspension of the boron in a solvent in the form of water.

9. A process according to claim 8 in which the boron is dissolved or suspended in the water at a temperature above 40°C.

10. A fertiliser containing boron, when produced by a process according to any one of the preceding claims.