Fertiliser coating containing micronutrients

Abstract

A single-step method for preparing a free-flowing, non-dusting micronutrient-coated particulate solid fertiliser material, the method comprising applying a single fluid onto particulate solid fertiliser material at ambient temperature without chemical reaction or chelation, said single fluid comprising a suspension of one or more micronutrient materials in an oil.

Claims

1. A method of preparing an oil-based suspension of a micronutrient material, the method comprising blending an oil with particles of a compound containing the micronutrient material to produce a suspension which is pumpable at ambient temperature; wherein 90% of the particles in the micronutrient material have sizes between 0.1 and 50 m; and wherein the suspension has a solids loading in the range 30 to 80 weight %.

2. The method according to claim 1, further comprising adding a dispersant to the oil prior to or during formation of the suspension.

3. The method according to claim 1, further comprising adding a rheology agent, thickener or anti-settling agent to the oil prior to or during formation of the suspension.

4. The method according to claim 1, further comprising adding a colorant to the oil.

5. The method according to claim 1, wherein the suspension has a viscosity in the range 500 to 6000 cPs at 20 C. measured on a Brookfield LVD viscometer using spindle 3 at 12 rpm.

6. The method according to claim 1, wherein 90% of the particles in the micronutrient material have sizes between 0.1 and 20 m.

7. The method according to claim 5 wherein the suspension has a viscosity in the range 2000 to 5000 cPs at 20 C. measured on a Brookfield LVD viscometer using spindle 3 at 12 rpm.

8. The method according to claim 1, wherein the suspension has a solids loading in the range of 50 to 80 weight %.

9. The method according to claim 1, wherein the method of preparing the oil-based suspension is essentially water-free.

Description

EXAMPLE 1

(1) The following example shows the formulation required to make 1 kg of an oil-based suspension of zinc oxide containing 50 weight % Zn (zinc oxide obtained from Umicore, Belgium, having an average particle size of approximately 0.5 m, 90% of particles less than 2 m).

(2) TABLE-US-00001 Rapeseed Oil 0.3320 kg Dispersant 0.0300 kg Blue Pigment Dispersion 0.0150 kg Zinc Oxide 0.6230 kg 1.0000 kg

(3) The above components are added in the order listed into a stirred beaker and mixing continued for 30 minutes. The resultant product is a fluid suspension with a viscosity of 4220 cPs at 20 C. as measured on a Brookfield LVD viscometer using spindle 3 at 12 rpm.

(4) Samples of the product were subjected to storage testing under various conditions. A sample stored at ambient temperature for a period of 4 months remained stable and fluid with no significant settlement of the suspended solids.

(5) The zinc oxide suspension described above was coated onto prilled urea at 20 C. using a rate equivalent to 5 litres per tonne of urea using the following method:

(6) 1 kg of prilled urea was added to a labscale drum blender and the blender started. 5 ml of the zinc oxide suspension was introduced via a syringe and blending continued for 2 minutes. The resultant product was evenly coated with micronutrient (equivalent to 0.47 weight % Zn), dust-free and free flowing.

(7) The suspension described in Example 1 was also coated onto two types of granular fertiliser, NPK 27-4-4 and calcium ammonium nitrate (CAN) (both obtained from Yara) at 20 C. Samples of both fertiliser grades (finished products obtained from the production plant and already treated with an anti-caking coating) were treated with the zinc oxide suspension using a rate to achieve a coating equivalent to 0.81 weight % on to the fertiliser. The resultant samples were tested for caking tendency compared against uncoated control samples of each fertiliser (that is, without the normal anti-caking coating) and samples of the normal finished fertiliser. The tests were carried out at 25 C. with 60% Relative Humidity and the results are shown in Table 1 below. The lower figures for the coated samples indicate less tendency to cake than the untreated samples and demonstrates the improvement conferred by the treatment.

(8) TABLE-US-00002 TABLE 1 Caking index for various fertilizers according to Example 1 Caking Index (gf) Uncoated NPK 27-4-4 3017 NPK 27-4-4 finished product from plant 1175 NPK 27-4-4 finished product + coated with Example 1 917 Uncoated CAN 975 CAN finished product from plant 583 CAN finished product + coated with Example 1 350

(9) The suspension described in Example 1 was also coated onto urea, calcium ammonium nitrate and an NPK blend in factory conditions with an ambient temperature of 30 C. at rates ranging from 2.1 litres per metric tonne of granular fertiliser to 4.2 litres per metric tonne of fertiliser. The resultant coated fertiliser was well-coated and free-flowing with low dust levels.

EXAMPLE 2

(10) The following example shows a formulation to make 1 kg of an oil-based suspension of colemanite, a boron-containing mineral with the chemical formula CaB.sub.3O.sub.4(OH).sub.3.H.sub.2O, containing about 7 weight % boron. (colemanite obtained from Eti Holdings AS, Turkey; ground to achieve a particle size specification of 90%<50 mthe particle size distribution of the actual batch used was 90%<13 m; 50%<7 m). The clay thickener was Pangel B5 (Tolsa S.A.) Sepiolite clay.

(11) TABLE-US-00003 Rapeseed Oil 0.3988 kg Dispersant 0.0357 kg Blue Pigment Dispersion 0.0107 kg Clay thickener 0.0054 kg Colemanite 0.5494 kg 1.0000 kg

(12) The above components are added in the order listed into a stirred beaker and mixing continued for 30 minutes. The resultant product is a fluid suspension with a viscosity of 3180 cPs at 20 C. measured on a Brookfield LVD viscometer using spindle 3 at 12 rpm.

(13) The suspension described in Example 2 was coated onto prilled urea at 8 C. using a rate equivalent to 5 litres per metric tonne of granular fertiliser. The resultant coated fertiliser was well-coated with micro-nutrient (equivalent to 0.05 weight % of boron) and free-flowing with low dust levels

EXAMPLE 3

(14) The following example shows a formulation to make 1 kg of an oil-based suspension of cuprous oxide, chemical formula Cu.sub.2O, containing about 86 weight % copper and with a particle size specification of 99%<5 m; 80%<2 m (obtained from Nordox Industries AS, Norway). The dispersant was Synthro Pon 9TD (Synthron) and the clay thickener was Pangel B5 (Tolsa S.A.) Sepiolite clay.

(15) TABLE-US-00004 Methylated Rapeseed Oil 0.1570 kg Dispersant 0.0400 kg Clay thickener 0.0030 kg Cuprous Oxide 0.8000 kg 1.0000 kg

(16) The above components are added in the order listed into a stirred beaker and mixing continued for 30 minutes. The resultant product is a fluid suspension with a viscosity of 2900 cPs at 20 C. measured on a Brookfield LVD viscometer using spindle 3 at 12 rpm.

(17) The suspension described in Example 3 was also coated onto prilled urea at 15 C. using a rate equivalent to 5 litres per metric tonne of granular fertiliser. The resultant coated fertiliser was well-coated with micro-nutrient and free-flowing with low dust levels

EXAMPLE 4

(18) The following example shows a formulation to make 1 kg of an oil-based suspension of manganese carbonate chemical formula MnCO.sub.3, containing about 44 weight % of manganese (obtained from Erachem Comilog S.A.). The manganese carbonate used was micronized to achieve a particle size specification of 100%<50 m; 90%<15 m; 50%<5 m. The dispersant was Decal FD (Devine Chemicals) and the fumed silica was Aerosil R812 (Evonik Industries AG).

(19) TABLE-US-00005 Methylated Rapeseed Oil 0.2991 kg Dispersant 0.0290 kg Blue Pigment Dispersion 0.0029 kg Manganese Carbonate 0.6603 kg Fumed Silica 0.0087 kg 1.0000 kg

(20) The above components are added in the order listed into a stirred beaker and mixing continued for 30 minutes. The resultant product is a fluid suspension with a viscosity of 2500 cPs at 20 C. measured on a Brookfield LVD viscometer using spindle 3 at 12 rpm.

(21) The suspension described in Example 4 was also coated onto granular calcium nitrate (which was already treated with an anti-caking coating) at 24 C. using a rate equivalent to 5 litres per metric tonne of granular fertiliser. The resultant coated fertiliser was well-coated with micro-nutrient and free-flowing with low dust levels

(22) It will be understood that the invention is not limited to the exemplified dispersing agent, and that any suitable natural and/or synthetic dispersant may be used. Suitable dispersing agents include, but are not limited to: fatty acids (FA), mono- and diglycerides, polymeric fatty acid derivatives such as Afcona 6226, Atlox LP1 and Decal FD and others.

(23) It will also be understood that the C.I. Pigment Blue 15:1 used in the examples is non-limiting and that other colorants known to those skilled in the art may be used. Examples include: Phthalocyanine blue (C.I. Pigment Blue 15, 15:1, 15:2, 15:3, 15:4), Aluminium Chlorophthalocyanine (C.I. Pigment blue 79). Other pigments than blue pigments may, of course, also be used.

SUMMARY

(24) The invention provides a method for the preparation and use of oil-based dispersions of plant micronutrients for coating solid granular, prilled or blended fertilisers.

(25) Benefits of the invention include:

(26) 1) Greater production flexibility than incorporation of micronutrients during the granulation or prilling process. 2) Superior coverage and the elimination of segregation and dusting compared to dry blending processes. 3) Simple one step (single-step) application process of applying only a single fluid (eliminating the need to add oil separately) without chemical or chelation reactions occurring during the process, in particular between the particulate solid fertilizer material and the single fluid comprising a suspension of one or more micronutrient materials in an oil. 4) Reduces the caking tendency of the final solid fertiliser when compared with aqueous-based systems. 5) Application at ambient temperatures provides a simple, robust process that does not require use of an external source of heat.