WO2014036572A2

WO2014036572A2 - Particulate products and process for manufacture thereof

Info

Publication number: WO2014036572A2
Application number: PCT/ZA2013/000063
Authority: WO
Inventors: Deon De Wet-Roos; Nicole HART
Original assignee: AECI Ltd
Current assignee: AECI Ltd
Priority date: 2012-08-31
Filing date: 2013-08-06
Publication date: 2014-03-06
Anticipated expiration: 2015-02-28
Also published as: ZA201406910B; WO2014036572A3

Description

PARTICULATE PRODUCTS AND PROCESS FOR MANUFACTURE THEREOF

FIELD OF THE INVENTION

The invention relates to providing a particulate product which has beneficial powder particles attached or bonded thereto.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a particulate product to which is attached or bonded a beneficial particulate substance having a particle size of below 20 pm by means of a polymer formulation.

The beneficial particulate substance may have a particle size of below 5 μιη, typically between 0.1 and 5 μηι, in one embodiment 1 pm. In another embodiment particles in the range 1 nm to 100 nm were used.

Thus the particle size range may be from 1 nm to 20 pm.

The beneficial particulate substance may be applied to the particulate product in the form of an emulsion, dispersion, or a suspension, typically a water-in-oil emulsion, although three phase emulsions may also be useable for this purpose.

The bonding may be by means of a polymeric coating formulation mixed or co-emulsified with the beneficial particulate substance.

Thus the beneficial particulate substance may be coated over the surface of the particulate product by being incorporated into an emulsion, dispersion, or suspension together with the polymer formulation. The polymer formulation is typically a viscous fluid. The emulsion, dispersion, or suspension of the beneficial particulate substance need not be blended with the polymer formulation prior to coating of the particulate product therewith.

The particulate product may range in size from 0 to 10 mm, and may be a particulate fertilizer such as a prill or granule, or a seed, or a granular material like perlite, or zeolite. The particulate product may range in size from 1 to 5 mm.

The beneficial particulate substance may be a trace element, a micronutrient, a chelate, a macronutrient, a micro-organism including for example a fungus, bacteria or innoculant, , a fulvate, pesticide, fertilizer micro-nutrient composition, a fungicide, a dye, or a colourant.

The beneficial particulate substance may be a blend of powders or a suspension of powders.

The particulate product may be a blend of particles.

The polymer formulation may be a biodegradable emulsion polymer or any emulsion polymer.

It may be a mixture of vegetable oils, waxes, saccharides and polysaccharides. It should be flowable at room temperature having a viscosity of no higher than 30 000 cP at 25 deg C.

Typically, the particles are coated in an amount of up to 20 % by weight using an emulsion polymer in which the beneficial particulate substance is emulsified.

The polymer may be applied in an amount of 3kg to 40 kg/mt of particles.

The attachment of the beneficial particulate substance to the particles may be achieved in 1 or multiple steps.

The invention extends to methods of preparation of the particulate products of the invention, said methods including the steps of:

- preparing an emulsion, dispersion, or suspension of beneficial particulate substance in a desired liquid;

- pre-coating a quantity of particles with a fluid polymer formulation; - before the polymer formulation has set on the particles, introducing the emulsion, dispersion, or suspension into contact with the coated particles; and

- bringing the dispersion, emulsion, or suspension into intimate contact with the particles for a period sufficient to allow the even distribution of the beneficial particulate substance throughout the quantity of particles.

The desired liquid may be a coating formulation formulated in part as a oil-in water emulsion or dispersion or a water-in-oil dispersion or emulsion of particulate matter or solutions of beneficial nutrient solids or liquids, a blend of an emulsion and a dispersion of particles or a blend of the emulsion and a slurry/suspension of particulate and/or dissolved matter or a blend of the emulsion and solid particulate matter of a required size and composition.

The quantity of particles may be a batch of particles which is to be processed either batchwise or continuously.

The method may include the further step of applying the same or another fluid polymer formulation to the particle now bearing the beneficial particulate substance thereby to provide an exterior coat thereto thereby to strengthen the initial bonding of the powder to the particles. DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In this specification, Biofix-® is a product of the applicant which is a polymeric formulation referred to in the Summary of the Invention. However, the invention is not limited to Biofix® or to any specific formulation described herein below, which examples are provided only by way of illustration of the principles of the invention.

Example 1 - Including Nano-sized nutrients into Biofix

Currently, the industry standard is that the amount of trace elements that can be attached to a fertilizer granule using Biofix as adhesive is limited to a ceiling value which has been determined to be roughly8% of fertilizer mass. At this value no more trace elements can be attached to the granule regardless of the amount of coating agent used. To go beyond the imposed limits of the current technology, the use of nano technology has been investigated. Nano-sized particles in the range of 10 to 100 nm has been sourced and mixed with the standard formulation of Biofix. Micro Element Percentage Required Mass per ton Biofix (kg)

Boron 0.03 0.3

Chlorine 1.0 10

Cobalt 0.05 0.5

Copper 0.05 0.5

Iron 0.2 20

Manganese 0.05 0.5

Molybdenum 0.005 0.05

Nickel 0.005 0.05

Sulphur 1.0 10

Zinc 0.1 1

Table 1. Required levels of micro elements to be incorporated into =coating product

From Table 1 it is evident that Boron, Molybdenum and Nickel are required at very low levels as micro-nutrients. Boron is required in very low concentrations in the agricultural industry: 10 to 70 g/ha for rice, 50 g/ha for maize and 150 g/ha for potatoes. Another element which proves to be a prime candidate is Molybdenum. The high solubility and nano-structure of Sodium Molybdate and the low required concentration levels in agriculture made this element suitable for consideration.

To illustrate the incorporation of nano particles into Biofix as the carrier phase, 15.76% Sodium Molybdate nano particles were incorporated into a Biofix formulation. The Biofix- Molybdenum was found to be very stable over time and has passed stringent accelerated testing. The efficacy of trace element attachment of Biofix- Molybdenum surpasses the industry standard of attachment. Example 2 - Biofix Blends with ultra-fine Zinc Oxide Dispersion (ZD), Copper dispersion (CD) and Sulphur Dispersion (SD).

Zinc Oxide and Copper dispersions were sourced commercially as well as the elemental sulphur dispersion. These dispersions were blended in various ratios with the standard Biofix formulation. The blends that included the sulphur dispersion were as follows:

1. 10 g Sulphur Dispersion and 40 g Biofix

2. 20 g Sulphur Dispersion and 40 g Biofix

3. 20 g Sulphur Dispersion, 20 g Zinc Oxide Dispersion and 40 g Biofix - 4. 10 g Zinc Oxide Dispersion and 40 g Biofix -

5. 20 g Zinc Oxide Dispersion and 40 g Biofix -

6. 20 g Activist Red Dispersion and 40g Biofix - Figure 1 shows microscope pictures of a) copper dispersion (20* magnification), b) Sulphur dispersion (40* magnification.), and c) Zinc Oxide dispersion (40*magnification.).

The particle sizes seem to be extremely fine down to 1 μιη and smaller. Apart from the sulphur dispersion it is difficult to see any individual particles although agglomerates are clearly visible for all the dispersions.

A second set of blends were also made with the Zinc Oxide and Copper Dispersion These were 50:50 and 60:40 blends of ZD:BF and CD:BF. The time it took to dry and the hardness of the films were investigated qualitatively by applying it onto a glass plate as 150 μητι thick films and comparing the films for dryness relative to a standard Biofix drawdown. Of the initial blends no. 2 and 3 were sprayed onto urea at a level of 0.4% to see if it would stick to the urea and cover it.

All coatings were done using a 150 μηι film applicator. The films were left to dry for 24h and dryness and hardness were investigated qualitatively. In the case of the urea coatings, 0.4% of the blends were sprayed on 1 kg samples of urea. Viscosities of the blends were measured using a Brookfield viscometer at room temperature with a no. 65 spindle at a speed of 30 rpm. Blending was achieved by mixing the Biofix and the dispersions using a spatula in a glass beaker.

The various coatings based on blends with Biofix gave relatively hard glossy coatings even after 2 hours. This is in contrast to the Biofix coating on its own that, although it was touch dry, could still be removed with relatively little effort from the glass plate. The blends with Biofix therefore resulted in coatings that appear to dry out faster than Biofix on its own.

The blend of 20 g sulphur dispersion, 20 g Zinc Oxide and 40 g Biofix gave a film that was quite hard (difficult to scratch) and it dried the fastest of all the films within an hour. In order to see if the sulphur blend and the combination of sulphur with zinc oxide could coat urea, 1 kg of urea was sprayed with 0.4% of these blends. Urea is chosen as it is considered one of the most difficult substrates to coat given its propensity to become wet and cake when sprayed with coatings containing significant amounts of water. The pictures below show the result of this exercise.

In Figure 2 are shown samples of coated urea. On the left is urea coated with a blend of 20 g sulphur dispersion and 40 g Biofix. On the right is a picture of urea coated with a blend of 20 g sulphur dispersion, 20 g zinc oxide dispersion and 40 g of Biofix .

The coated urea shows good coverage even at the low level of 0.4% and dried out quickly within a couple of hours. Viscosities of the initial blends were tested and all of them had viscosities in the region of 1000 cP. No separation was evident after standing for three days. The viscosities of the zinc oxide blends changed significantly to 2108 cP for the 50:50 blend and 2523 cP for the 60:40 blend. The viscosities for the copper dispersion blends were 908 cP for the 50:50 blend and 848 cP for the 60:40 blend. By varying the rheometer spindle revolutions per minute it was shown that these blends are all shear thinning which means they can be applied using methods such as spray nozzles.

Example 3 - Reformulating Biofix Formulation using a Water-in-oil Emulsion to deliver Micro Nutrients

This technique involves dissolving the metal salt in water first and then emulsifying this solution in an oil phase using a surfactant such as a suitable non-ionic surfactant. Of importance is to note that not all the salts of certain micro elements have the same solubility properties. For example zinc sulphate is reported to have a solubility of 57.7 g/100 ml water while zinc chloride has a solubility of 432g/100 ml water. The selection of salts should then require the highest solubility where possible to get the highest concentration of a specific micro element into the Biofix.

Typically, a sample of recycled Sunflower Oil (RSO) will be taken and a suitable amount of non- ionic surfactant will be added. After dissolving the A suitable non-ionic surfactant in the RSO the aqueous phase can be added and stirred into the oil phase to form a water-in-oil emulsion. Table 2 illustrates the levels of the compounds required to make a stable water-in-oil emulsion.

Table 2. Ingredients used to synthesise a water-in-oil emulsion containing zinc and potassium as micro element.

Typical levels of micro elements required are given in Table 1. Table 1 also stipulates the amount of micro element that would be required per ton of Biofix to achieve the required percentage value.

The emulsion formed in this way using RSO as oil phase is stable. Biofix was made using this water-in-oil emulsion in the normal way using for example 10 to 24%f a plant derived oil and from 35 to 45% each of a product that constitutes a surface active composition derived from the by-products of fermentation and a concentrated solution of mono- di and polysaccharides and 0.2% of a non-ionic sterically stabilizing dispersant.

Once Biofix is made using the water-in-oil emulsification technique a product is formed that remains stable for months. Typical results obtained thus far for Biofix based on this method are given below in Table 3.

Table 3. Physical properties of Biofix sample containing zinc and potassium salts.

The stability test using a centrifuge (3000 rpm for 5 minutes at room temperature) indicates that no separation occurs of the oil phase. Figure 3 below shows an example of the vial containing the modified Biofix . In Figure 3, in the test tube is a sample of modified Biofix showing no oil separation after exposure to centrifuge. Qualitative tests done to compare the stickiness and dryness of the final film also yielded positive results. In a second experiment a solution was prepared by dissolving the metal salts in water (See Table 4) and then emulsifying in the oil phase.

Table 4. Metal salts dissolved and emulsified in oil.

As first level experimental screening test, 10%(m/m) of the metal ion solution (Table 3) was mixed with 88% (m/m) oil in the presence of 2% (m/m) Span 65 under stirring. This gave a homogeneous water in oil emulsion, which was then used as the oil phase in the preparation of Biofix .

By increasing the ratio of the water-in-oil emulsion or the concentrations of the metal salts in the emulsion, the trace elements levels can be increased significantly. Combining a number of metal salts as indicated in the Table 5 can result in some salts not dissolving fully. However, certain combinations of metal salts such as zinc chloride and potassium chloride can still be co- dissolved at relatively high levels. Metals

Biofix Biofix

Incorporated

(Standard) (Emulsification) into Biofix Target

Mass (%) Mass (%) Mass (%)

Molybdenum Mo 0.005 0.000% 0.002%

Nickel Ni 0.005 0.000% 0.002%

Manganese Mn 0.05 0.003% 0.021%

Iron Fe 0.2 0.021% 0.051%

Zinc Zn 0.1 0.000% 0.050%

Copper Cu 0.05 0.000% 0.014%

Cobalt Co 0.05 0.000% 0.010%

Table 5. ICP analysis of Biofix samples with added nutrients.

A storage stability test of the resulting Biofix showed no signs of separation even after storage for 3 months. The experiment in which a solution of salts was mixed with Biofix also yielded a stable emulsion.

Example 4. - Blending Biofix with a Slurry of Micro Nutrient Salts in Water As noted previously, dissolving metal salts to fulfil the requirements for the levels of micro nutrients in Table 2 can result in the formation of a slurry instead of a clear solution of these salts. An example of such a slurry can for example (but not limited) be obtained by combining ZnO, Fe₂0₃, ZnS0 , CuO, Mn0₂, H₃B0₃ and MgO. The resultant slurry in the minimum amount of water can easily be blended with Biofix at various ratios to provide a stable dispersion of metal salts in Biofix.

In addition, metal salt slurries composed of minute submicron particles in a carrier such as the sulphur dispersion described in example 3 can be blended with Biofix in various ratios to provide stable blends of elemental sulphur and metal salt dispersions in Biofix. A typical example of this is to blend 82 g ZnS0₄.H₂0 together with 50 g of distilled water and 200 g sulphur dispersion under high shear for half an hour. Following this a stable dispersion is formed that can be blended with Biofix. An example of such a blend involves 200 g of the sulphur dispersion described above with 200 g of Biofix. To ensure good wetting of the substrate a small amount of surfactant such as dodecylsulfosuccinate maleate can be added in a small amount of water (30 g).

Claims

1. A particulate product to which is attached or bonded a beneficial particulate substance having a particle size of below 20 pm by means of a polymer formulation.

2. A particulate product as claimed in claim 1 , wherein the beneficial particulate substance has a particle size of below 5 pm.

3. A particulate product as claimed in claim 2, wherein the beneficial particulate substance has a particle size of between 0.1 and 5 pm.

4. A particulate product as claimed in claim 2, wherein the beneficial particulate substance has a particle size of 1 pm.

5. A particulate product as claimed in claim 1 , wherein the beneficial particulate substance has a particle size of in the range 1 nm to 100 nm.

6. A particulate product as claimed claim any one of the preceding claims, wherein the beneficial particulate substance is applied to the particulate product in the form of an emulsion, dispersion, or a suspension.

7. A particulate product as claimed in claim 6, wherein the beneficial particulate substance is applied to the particulate product in the form of a water-in-oil emulsion or a three phase emulsion.

8. A particulate product as claimed in any one of the preceding claims, wherein the beneficial particulate substance is selected from the group including a trace element, a micronutrient, a chelate, a macronutrient, a micro-organism, a fulvate, a pesticide, a fertilizer micro-nutrient composition, a fungicide, a dye, or a colourant.

9. A particulate product as claimed in claim 8, wherein the micro-organism is selected from a fungus, bacteria, and an inoculant.

10. A particulate product as claimed in any one of the preceding claims, wherein the beneficial particulate substance is a blend of powders or a suspension of powders.

11. A particulate product as claimed in any one of the preceding claims, wherein the bonding of the beneficial particulate substance to the particulate product is by means of a polymeric coating formulation mixed or co-emulsified with the beneficial particulate substance.

12. A particulate product as claimed in claim 11, wherein the polymeric coating formulation is a viscous fluid.

13. A particulate product as claimed in any one of the preceding claims, which ranges in size from 0 to 10 mm.

14. A particulate product as claimed in any one of the preceding claims, which is selected from a particulate fertilize prill or granule, a seed, a granular material, perlite, zeolite, or a blend thereof.

15. A particulate product as claimed in any one of preceding claims 11 to 14, wherein the polymeric coating formulation is a biodegradable emulsion polymer.

16. A particulate product as claimed in any one of claims 11 to 15, wherein the polymeric coating formulation is one or more of a mixture of vegetable oils, waxes, saccharides, and polysaccharides, flowable at room temperature and having a viscosity of no higher than 30 000 cP at 25 deg C.

17. A particulate product as claimed in any one of claims 15 and 16, coated in an amount of up to 20 % by weight of the uncoated particulate product using the emulsion polymer in which the beneficial particulate substance is emulsified.

A method for preparation of coated particulate products, said method including the steps of:

- pre-coating a quantity of particles with a fluid polymer formulation;

- before the fluid polymer formulation has set on the particles, introducing the emulsion, dispersion, or suspension into contact with the coated particles; and

19. A method as claimed in claim 18, wherein the desired liquid is a coating formulation formulated in part as one or more of oil-in water emulsion or dispersion, a water-in-oil dispersion, water-in-oil solutions of beneficial nutrient solids or liquids, a blend of an emulsion and a dispersion of particles, a blend of the emulsion and a slurry or suspension of particulate matter, and a blend of the emulsion and solid particulate matter, each of a required size distribution and composition.

20. A method as claimed in claim 18 or claim 19, which includes the further step of applying the same or another fluid polymer formulation to the particle now bearing the beneficial particulate substance thereby to provide an exterior coat thereto thereby to strengthen the initial bonding of the beneficial particulate substance to the particles.