DESC:FIELD
The present disclosure relates to a process for the preparation of granulated phosphogypsum fertilizer composition.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which it is used to indicates otherwise.
Micronutrient: Micronutrients are essential elements such as boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn), nickel (Ni) and chloride (Cl) required for plant growth in very small quantities.
Secondary nutrients: Secondary nutrients are the essential elements such as calcium (Ca), magnesium (Mg), and sulfur (S) required for plant growth in smaller quantity.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Phosphogypsum is a by-product produced from the processing of phosphate rock in plants producing phosphoric acid and phosphate fertilizers, such as superphosphate. Phosphogypsum is widely used as a soil conditioner for soil-air interaction and also allows flow of water avoiding problems due to water logging. Further, the application of phosphogypsum is increased as it works as a source of sulphur and calcium nutrients and is used in the fertilizer composition. Conventionally, the phosphogypsum is applied in a powder from individually or through fertilizer composition, wherein it is observed that the application of powder form of phosphogypsum has the limitations of dusting, non-uniform distribution and ease of handling.
There is, therefore, felt a need for a process for preparing the granulated fertilizer composition that mitigates the drawbacks mentioned hereinabove.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to is to provide a process for the preparation of fertilizer composition.
Another object of the present disclosure is to provide a process which is simple and inexpensive.
Yet another object of the present disclosure is to provide a fertilizer composition.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a process for preparing a granulated phosphogypsum fertilizer composition. Phosphogypsum having a moisture content in the range of 2% to 14% is obtained and mixed with a first binder and optionally with a second binder to obtain a first homogenized mixture. To the first homogenized mixture, at least one source of micronutrient and at least one source of secondary nutrient is mixed to obtain a second homogenized mixture. The second homogenized mixture is granulated to obtain a product mixture comprising a granulated fertilizer composition. The product mixture is dried at a temperature in the range of 60 to 80 °C to obtain the granulated fertilizer composition. The granules have a particle size in the range of 1 mm to 5 mm.
The present disclosure further relates to a granulated phosphogypsum fertilizer composition. The fertilizer composition comprises phosphogypsum in an amount in the range of 75 wt.% to 85 wt.% of the total weight of the fertilizer composition, wherein the moisture content of the phosphogypsum is in the range of 2% to 14%; a first binder in an amount in the range of 15 wt.% to 25 wt.% of the total weight of the fertilizer composition; a second binder in an amount in the range of 0.01 wt.% to 1 wt.% of the total weight of the fertilizer composition; a source of micronutrient in an amount in the range of 0.01 wt.% to 3 wt.% of the total weight of the fertilizer composition; and a source of secondary nutrient in an amount in the range of 0.05 wt.% to 5 wt.% of the total weight of the fertilizer composition.
The granulated phosphogypsum fertilizer composition is characterized by having a particle size in the range of 1 mm to 5 mm, a crushing strength in the range of 0.5 kg to 5 kg per granules and a moisture content in the range of 0.1% to 7%.
DETAILED DESCRIPTION
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details, are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
In one aspect, the present disclosure provides a process for preparing a granulated phosphogypsum fertilizer composition. The process is described in detail herein below.
Phosphogypsum having a moisture content in the range of 2% to 14% is obtained and mixed with a first binder and optionally with a second binder to obtain a first homogenized mixture. The first homogenized mixture is mixed with at least one source of micronutrient and at least one source of secondary nutrient to obtain a second homogenized mixture. The second homogenized mixture is granulated for a time period in the range of 5 to 20 min to obtain a product mixture comprising a granulated fertilizer composition. The product mixture is further dried at a temperature in the range of 50 to 120?C to obtain the granulated fertilizer composition having a particle size in the range of 1 mm to 5 mm.
Phosphogypsum is a by-product having more than 25% moisture which is dried under the sun to reduce the moisture content to 14%. The phosphogypsum is a granulated phosphogypsum characterized by having a moisture content in the range of 2% to 14%. In an exemplary embodiment of the present disclosure, the moisture content of the phosphogypsum is 6%.
The first binder is selected from bentonite clay, zeolite, dolomite, and a combination thereof. In an exemplary embodiment of the present disclosure, the first binder is bentonite clay.
The second binder is selected from calcium lignosulfonate, ammonium lignosulfonate, and a combination thereof. In an exemplary embodiment of the present disclosure, the second binder is calcium lignosulfonate.
In an embodiment of the present disclosure, the process of granulation comprises agitating the second homogenized mixture at a speed in the range of 20 rpm to 40 rpm, while spraying a solution of a second binder to the second homogenized mixture comprising the first binder to obtain a product mixture comprising the granulated fertilizer composition.
The solution of a second binder is an aqueous solution of the second binder with a concentration in the range of 18 to 25% with respect to the total weight of the composition.
In another embodiment of the present disclosure, the process of granulation comprises agitating the second homogenized mixture at a speed in the range of 20 rpm to 40 rpm, while spraying water to the second homogenized mixture comprising combination of the first binder and the second binder to obtain a product mixture comprising fertilizer composition.
The source of micronutrient is at least one selected from the group consisting of zinc-ethylenediaminetetraacetic acid (Zn-EDTA), disodium octaborate tetrahydrate, and a combination thereof.
The source of secondary nutrient is magnesium sulfate (MgSO4), Mg-EDTA, dolomite, and a combination thereof.
In another aspect, the present disclosure provides a granulated phosphogypsum fertilizer composition comprising phosphogypsum in an amount in the range of 75 wt.% to 85 wt.% with a moisture content in the range of 2% to 14%; a first binder in an amount in the range of 15 wt.% to 25 wt.%; a second binder in an amount in the range of 0.01 wt.% to 1 wt.%; a source of micronutrient in an amount in the range of 0.01 wt.% to 3 wt.%; and a source of secondary nutrient in an amount in the range of 0.05 wt.% to 5 wt.%.
In accordance with an embodiment of the present disclosure, the granulated phosphogypsum fertilizer composition comprises phosphogypsum in an amount in the range of 78 wt.% to 83 wt.% with a moisture content in the range of 5% to 10%; a first binder in an amount in the range of 18 wt.% to 23 wt.%; a second binder in an amount in the range of 0.05 wt.% to 0.8 wt.%; a source of micronutrient in an amount in the range of 0.04 wt.% to 2.5 wt.%; and a source of secondary nutrient in an amount in the range of 0.1 wt.% to 4 wt.%.
The granulated phosphogypsum fertilizer composition is characterized by having a particle size in the range of 1 mm to 5 mm, a crushing strength in the range of 0.5 kg to 5 kg per granules and a moisture content in the range of 0.1% to 7%.
The fertilizer composition in the form of granules are advantageous in terms of their uniform distribution. The conventional fertilizer composition comprises phosphogypsum in powdered form that has the limitations of dusting, non-uniform distribution and ease of handling. To overcome the drawbacks of the conventional fertilizer composition, the present disclosure provides a fertilizer composition in a granulated form.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
EXPERIMENTAL DETAILS
Experiment 1: Preparation of fertilizer composition in accordance with the present disclosure
750 g of dried phosphogypsum having a moisture content of 6% was mixed with 168 g of bentonite clay to obtain a first homogenized mixture.
Further, 16.79 g of Zn-EDTA, 4.55 g of MgSO4 and 25 g of Disodium Octaborate Tetrahydrate were mixed to the first homogenized mixture to obtain a second homogenized mixture. The second homogenized mixture is granulated in a rotating pan granulator with a speed of 30 rpm. A solution of 50 g calcium lignosulphonate in 260 ml water was prepared and stored in a spray gun tank and was sprinkled slowly to the rotating mix for a time period of 10 min to obtain granules. The granules were sieved and the size fraction of 2 to 4 mm was separated. The separated fraction of granules was introduced to a rotating drum dryer rotating at a speed of 7 rpm with hot air blow of contact temperature of 80°C.

The granules obtained by the above process is analyzed and tabulated in table 1
Table 1
Parameter Result
Granule size 2 to 4 mm
Yield 39 %
Crushing Strength (Average of 40 granules) 4 kg/granule
CaO 23.03 %
Sulphate 41.24 %
P2O5 0.48 %
Zinc 0.19 %
Magnesium 0.22 %
Boron 0.46%

Comparative Experiment 2: Preparation of fertilizer composition
781 g of phosphogypsum, 200 g of bentonite, 2.5 g of ZnO, 1 g of micronized elemental sulphur, 8.5 g of MgSO4 and 6 g of Disodium Octaborate Tetrahydrate were mixed and introduced to a pan granulator rotating at 30 rpm. Further, 250 ml water was sprayed to the rotating mix in the pan for a time period of 10 min to obtain granules. The granules formed were sieved for size range 2 to 4 mm and introduced to a rotating pan drier having hot air flow with 80°C contact temperature.

The granules obtained by the above process is analyzed and tabulated in table 2

Table 2
Parameter Result
Granule size 2 to 4 mm
Yield 45 %
Crushing Strength (Average of 10 granules) 2.5 kg/granule
CaO 23.97 %
Sulphate 40.13 %
Elemental sulphur 1 %
P2O5 0.47 %
Zinc 0.1 %
Magnesium 0.45 %
Boron 0.11 %

Comparative Experiment 3: Process for the preparation of fertilizer composition in large scale
In the first step, sources of nutrients, (80 kg) corresponding to ZnO, MgSO4 and elemental sulphur and disodium octaborate tetra hydrate was added to 1520 kg of phosphogypsum and 400 kg of bentonite clay and mixed in a homogenizer to obtain a first homogenized mixture. In the next step, the first homogenized mixture was loaded on a continuous basis to a pan granulator having 2 m diameter and 0.5 m depth rotating at 34 rpm. Water was sprinkled using an atomizer continuously to obtain product granules. The product granules were taken to a vibrating screen for size separation and the required size materials were moved to a dryer. Undersize and oversize materials were reprocessed and fed back to the granulator pan.
The granules obtained by the above process is analyzed and tabulated in Table 3
Table 3:
Parameter Result
Granule size 2 to 4 mm
Crushing Strength (Average of 20 granules) 2 kg/granule
CaO 15.89 %
Sulphate 28.60 %
Zinc 0.75 %
Magnesium 0.36 %
Boron 0.22 %

Experiment 4: Process for the preparation of fertilizer composition in large scale
The raw materials used are tabulated in table 4.
Table 4.
Raw materials Weight (kg)
Phosphogypsum 39050
Bentonite 10000
ZnO 125
Elemental Sulphur 50
MgSO4 425
Disodium Octaborate Tetra Hydrate 300
Calcium Ligonsulphonate 50

The raw materials tabulated in table 4 except the second binder (calcium lignosulphonate) were initially mixed in a homogenizer and stored in a hopper to obtain a homogenized mixture. The second binder was added to water to form a binder solution and stored in a tank equipped with a sprinkler with pump. The homogenized mixture was then loaded on a continuous basis to a drum granulator having 1.5 m diameter and 8 m length rotating at 34 rpm. The binder solution was sprinkled using the sprinkler continuously to obtain product granules. The product granules were taken to a vibrating screen for size separation and the required size materials were moved to a dryer. Undersize and oversize materials were reprocessed and fed back to the granulator pan and the granules having particle size of 2mm to 4mm were separated. The granules obtained by the above process is analyzed and tabulated in table 5.
Table 5:
Parameter Result
Granule size 2 to 4 mm
Crushing Strength (Average of 20 granules) 4.5 kg/granule
Ca 12.87 %
Sulphur 12.84 %
Zinc 0.75 %
Magnesium 0.32 %
Boron 0.22 %

A comparison of resulting crushing strength in the above examples shows that when two binders are used (experiments 1 and 4), the granules formed are having more crushing strength. Increased crushing strength helps reducing loss due to aberration and powdering. When the product is stacked for a longer time or during handling and transportation, granules of better crushing strength will suffer less damage.
TECHNICAL ADVANCEMENTS AND ECONOMICAL SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a process for preparing granular phosphogypsum fertilizer composition, wherein:
- the process is simple and economical; and
- the granules prepared by the process of the present disclosure has increased crushing strength.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation. ,CLAIMS:WE CLAIM:
1. A process for preparing a granulated phosphogypsum fertilizer composition, said process comprising the following steps:
a) obtaining phosphogypsum having a moisture content in the range of 2% to 14%;
b) mixing a first binder and optionally, a second binder with phosphogypsum to obtain a first homogenized mixture;
c) mixing at least one source of micronutrient and at least one source of secondary nutrient to said first homogenized mixture to obtain a second homogenized mixture;
d) granulating said second homogenized mixture to obtain a product mixture comprising the granulated fertilizer composition; and
e) drying said product mixture at a temperature in the range of 50?C to 120°C to obtain the granulated phosphogypsum fertilizer composition having a particle size in the range of 1 mm to 5 mm.
2. The process as claimed in claim 1, wherein said phosphogypsum is a granulated phosphogypsum characterized by having a moisture content in the range of 5% to 10%.
3. The process as claimed in claim 1, wherein the first binder is selected from bentonite clay, zeolite, dolomite, and a combination thereof.
4. The process as claimed in claim 1, wherein the first binder is bentonite clay.
5. The process as claimed in claim 1, wherein the second binder is selected from calcium lignosulfonate, ammonium lignosulfonate, and a combination thereof.
6. The process as claimed in claim 1, wherein the second binder is calcium lignosulfonate.
7. The process as claimed in claim 1, wherein the source of the micronutrient is selected from zinc-ethylenediaminetetraacetic acid (Zn-EDTA), disodium octaborate tetrahydrate, and a combination thereof.
8. The process as claimed in claim 1, wherein the source of the secondary nutrient is selected from magnesium sulfate (MgSO4), Mg-EDTA, Dolomite, and a combination thereof.
9. The process as claimed in claim 1, wherein the step (d) of granulation comprises agitating said second homogenized mixture at a speed in the range of 20 rpm to 40 rpm, while spraying a solution of a second binder to said second homogenized mixture to obtain a product mixture comprising said granulated fertilizer composition, wherein said second homogenized mixture comprises phosphogypsum and the first binder.
10. The process as claimed in claim 1, wherein said solution of a second binder is an aqueous solution of said second binder having a concentration in the range of 18 to 25%, with respect to the total weight of the composition.
11. The process as claimed in claim 1, wherein the step (d) of granulation comprises agitating said second homogenized mixture at a speed in the range of 20 rpm to 40 rpm, while spraying a water to said second homogenized mixture to obtain a product mixture comprising fertilizer composition, wherein said second homogenized mixture comprises phosphogypsum, the first binder and the second binder.
12. A granulated phosphogypsum fertilizer composition obtained by the process as claimed in claim 1 comprising;
i. phosphogypsum in an amount in the range of 75 wt.% to 85 wt.% of the total weight of the fertilizer composition, wherein a moisture content of the phosphogypsum is in the range of 2% to 14%;
ii. a first binder in an amount in the range of 15 wt.% to 25 wt.% of the total weight of the fertilizer composition;
iii. a second binder in an amount in the range of 0.01 wt.% to 1 wt.% of the total weight of the fertilizer composition;
iv. a source of micronutrient in an amount in the range of 0.01 wt.% to 3 wt.% of the total weight of the fertilizer composition; and
v. a source of secondary nutrient in an amount in the range of 0.05 wt.% to 5 wt.% of the total weight of the fertilizer composition,
wherein, said granulated phosphogypsum fertilizer composition is characterized by having a particle size in the range of 1 mm to 5 mm, a crushing strength in the range of 0.5 kg to 5 kg per granules and a moisture content in the range of 0.1% to 7%.