Patent Application
20240270655
The present invention relates to a phosphate-based glass fertilizer and a method for producing the same.
Fertilizers that are used for increasing agricultural yield are basically divided into two groups: organic and chemical fertilizers. Among them; organic fertilizers that include vermi-compost, treatment sludge, and animal and plant wastes are generally used as soil promoters because of their low nutritional grade. On the other hand, fertilizers that are classified as chemical fertilizers such as diammonium phosphate, urea, NPK (nitrogen-phosphorus-potassium) are nowadays vastly used due to their high nutritional grade. Yet, although they have a rich nutritional grade, chemical fertilizers in the market start to be replaced with controlled release fertilizers due to their rapid dissolving behaviour that causes important environmental problems.
Chemical fertilizers that are widely used for increasing agricultural yield demonstrate a very rapid dissolving behaviour. As a result, nutritional grade of the chemical fertilizer is quickly washed-off from soil, and necessary nutritional elements cannot be taken into plant bodies in a sufficient extent. Due to this rapid dissolving behaviour, different chemical fertilizers are usually required to be applied to the soil in different periods throughout a plant growth process. In addition, depending to its type, the chemical fertilizer may cause salinity or acidity in the soil, resulting in deterioration of the soil structure, thereby reducing the agricultural productivity. Chemical fertilizers may further cause many other environmental problems including eutrophication, nitrate accumulation in water, and heavy metal accumulation in soil.
Controlled release fertilizers are developed for overcoming such issues that are related to chemical fertilizers. Commercially available controlled release fertilizers are equivalent to chemical fertilizers in terms of their nutritional grades; yet their outer layers include a sulphur- or polymer-based coating for decelerating the release. This measure enables an environmentally friendly and high-yield fertilization. 50% of sulphur-coated controlled release fertilizers fracture during transportation, resulting in a rapid release of nutritional elements. Most of polymer coatings are not biodegradable, therefore they can cause toxic effects in soil.
In brief, in aspects that are considered important in view of the present specification, behaviour of known fertilizers can be classified as follows:
In the light of the evaluations listed above; it is considered important to provide a fertilizer with a favourable controlled release behaviour, that is advantageous in view of the aspects that are taken into account within the context of the present invention; and to propose a method for preparation of the same.
Primary object of the present invention is to overcome the above-mentioned shortcomings of the prior art. The present invention provides a phosphate-based glass fertilizer that goes beyond the prior art in terms of dissolving rate, soil pH balance, biodegradability, nutritional grades, manner of application and environmental impact; and proposes a method for producing the same starting from a glass blend.
Said glass fertilizer and the glass blend that is prepared in the step i in the method for producing said fertilizer includes, with respect to the combined total molar amount of components that are included in the composition, P2O5 within the range between 40% and 50% mol/mol, K2O within the range between 8% and 17% mol/mol, CaO within the range between 15% and 25% mol/mol, Al2O3 within the range between 3% and 10% mol/mol, and Na2O within the range between 8% and 17% mol/mol.
The glass fertilizer and respective glass blend preferably includes polyphosphate in a molar proportion of 40%, or metaphosphate in a molar proportion of 50%, with respect to the combined total molar amount of components in the composition.
In the glass fertilizer and glass blend compositions, the molar amounts of K2O and Na2O are preferably equal to each other.
In a preferred implementation of the present invention, the glass fertilizer and glass blend include SiO2 in a molar proportion of up to 10%, with respect to the combined total molar amount of components that are included in the composition.
In a preferred implementation of the present invention, the glass fertilizer and glass blend include one or more micro nutritional elements (micronutrients) selected from Mn, Mo, B, Fe, Cu and Zn. The glass fertilizer and glass blend preferably include one or more micro nutritional elements selected from MnO, MoO3, B2O3, Fe2O3, CuO and ZnO, and more preferably the glass fertilizer and glass blend include all of said micronutrients. The glass fertilizer and glass blend preferably include one or more, more preferably all of the following components; provided that their combined molar amount does not exceed 6% of the combined total molar amount of materials that constitute the respective composition:
MnO with a molar proportion within the range between 0.1% and 1%, MoO3 with a molar proportion within the range between 0.1% and 1%, B2O3 with a molar proportion within the range between 0.1% and 1%, Fe2O3 with a molar proportion within the range between 0.1% and 1%, CuO with a molar proportion within the range between 0.1% and 1% and ZnO with a molar proportion within the range between 0.1% and 1%.
The glass fertilizer and glass blend preferably include one or more of transition metals that are indicated in the periodic table of elements, provided that their combined molar amount does not exceed 1% of the combined total molar amount of materials in the composition. Said transition metals can preferably be one or more selected from Ni and Co.
The method for preparing the glass fertilizer according to the present invention includes: preparation of the glass blend, then in a step ii, melting the glass blend preferably at a temperature above 1000° C., more preferably at a temperature within the range between 1000° C. and 1300° C. After said melting step, the method according to the present invention includes a step iii directed to subjecting the molten glass blend to a rapid cooling to obtain pieces in the form of frit or granules.
After the step iii, the method preferably includes a milling process for obtaining particles with a mean particle size of up to 0.50 mm, more preferably within the range between 0.10 mm and 0.50 mm, even more preferably within the range between 0.25 mm and 0.50 mm.
Glass compositions can contain macronutrients (e.g., P, K, Ca and Mg) and micronutrients (e.g., Mn, Mo, B, Fe, Cu, Zn) that are necessary for the nutrition of a plant, and the dissolving behaviour can be controlled by varying the composition. With the controllable dissolving behaviour, glass fertilizers contribute to the nutrition of plants by releasing the nutrients they contain to the soil. The dissolving rate is variable in a wide range by introduction of an additional component into the glass composition, or by changing the ratios of the components in the composition structure. By this way it can be ensured that the macro- and micronutrients that are necessary for nutrition of plants are slowly released in a controlled manner. It is further possible to achieve desired dissolving rates under different/variable conditions, by tuning the compositions of glass fertilizers in accordance with plant, soil and climate characteristics. Glass is acknowledged as a 100% recyclable material and it does not release any toxic matter when introduced to soil. Accordingly, a glass fertilizer would provide an effective plant growth thanks to its tunable/controllable dissolving rate, rich nutrients content and environmentally friendly character.
Phosphate-based glasses have a potential to be used as a controlled-release fertilizer that increases agricultural yield, by being environmentally friendly, their ability to include macro- and micro nutrients in their compositions, and their broad-range dissolving rate tunability via composition control.
The phosphate-based glass fertilizer according to the present invention can contain macro- and micronutrients that are necessary for plant growth, in its composition; and its dissolving behaviour can be controlled throughout a broad range by modifications in the composition. The tunability of dissolving behaviour by modifying the composition provides an effective plant growth; furthermore, a sufficient extent of nutrients can be provided by applying to the soil even only once at the beginning of the seed-time, since the release of nutrients takes place throughout a prolonged duration. In addition, glass is a 100% recyclable material and does not release any toxic matter to the soil. Hence, glass fertilizers are completely environmental friendly, never causing any degradation in the soil structure. Additionally, the composition of the glass fertilizer according to the present invention enables the achievement of desired dissolving rates for various different conditions, by means of tuning its composition in accordance with plant, soil and climate-related characteristics.
The phosphate-based glass fertilizer according to the present invention includes a plurality of macronutrients, and preferably, further includes a plurality of micronutrients.
The present invention further proposes a method for production of said glass fertilizer. The method according to the present invention includes the following steps:
Said glass blend is considered as a phosphate-based glass blend because of the amount of phosphate (P2O5) content in its composition. Therefore, the fertilizer that is obtained from said blend is a phosphate-based glass fertilizer. In the glass blend that is prepared in the step i of the method according to the present invention, and in the glass fertilizer composition obtained therefrom, the range of the P2O5 amount (that can be named as molar % concentration, or % concentration) is observed to be suitable for formation of a network structure within the glass fertilizer, that enables the dissolving rate to be optimized. Thanks to said amount range, phosphate is hereby acknowledged as a component that has an important role in prolonging the dissolving time to a desired extent, that is, in decreasing the dissolving rate to a desired extent.
P2O5 used in the step i of the method can be obtained from one or more of its compounds including orthophosphoric acid, ammonium dihydrogen orthophosphate, diammonium hydrogen orthophosphate, potassium dihydrogen orthophosphate, tri-calcium phosphate, aluminium orthophosphate, or mixtures thereof. Prior to the step i, the method can include a respective step of obtaining P2O5.
P2O5 used in the step i of the method can include, for instance, metaphosphate, polyphosphate or mixtures thereof. In a preferred implementation of the invention, in the cases where the phosphate content is close to the upper limit of the respective range, the phosphate content can substantially include metaphosphate. In another preferred implementation of the invention, in the cases where the phosphate content is close to the upper limit of the respective range, the phosphate content can substantially include polyphosphate. For instance, molar proportion of the polyphosphate content in the glass blend can be 40%. In another exemplary implementation, molar proportion of the metaphosphate content in the glass blend can be 50%.
In the case where the glass blend and the fertilizer obtained therefrom includes more than one alkali metal compounds (K2O and Na2O) in combination, and in particular, in the case where these are present in substantially equal molar amounts with regard to each other, said blend and the fertilizer obtained therefrom are considered to include “mixed alkali”. Thanks to the mixed alkali effect, the dissolving rate of such glass fertilizer is dramatically prolonged, in particular, in the case where the K2O and Na2O contents are substantially equal to each other. Accordingly, in a preferred implementation of the present invention, in the step i of the method and in the glass fertilizer composition, the molar amounts of sodium and potassium can be substantially equal to each other. Within this context, the step i of a preferred implementation of the method according to the present invention, can include preparation of the glass blend such that the molar percentage of K2O and the molar percentage of Na2O are equal to each other. Accordingly, the glass fertilizer obtained by a preferred implementation of the present invention can contain potassium and sodium with substantially equal molar proportions with regard to each other.
CaO used in the step i of the method can be obtained from any one of the following compounds: tri-calcium phosphate, calcium sulphate, calcium carbonate, gypsum, dolomite, calcium cyanamide, or from a mixture thereof. The method can include such step of obtention prior to the step i.
Alumina and mixed alkali contents and their respective amounts in the glass blend and in the fertilizer composition obtained therefrom, provides controlled release with dissolving times of much longer than 40 days.
It is observed that the alumina (Al2O3) in the glass blend increases the chemical resistance of the glass fertilizer, and lowers its dissolving rate. This fact is interpreted as that alumina causes cross-linking between phosphate chains. Yet, in the cases where the alumina molar content exceeds 10% of the combined total molar amount of materials constituting the glass blend, it is observed that the resulting glass fertilizer has a decreased chemical resistance and an increased dissolving rate.
The method according to the present invention and the glass fertilizer obtained as the resulting product of the method provides an advantageous dissolving behavior even in the case where the respective composition does not include SiO2. SiO2 relatively decreases the chemical resistance of the fertilizer in neutral media, but increases the chemical resistance when in acidic media. Hence, it is observed that in the case where SiO2 has been introduced into the composition during preparation of the glass blend in the step i of the method, a prolonged dissolving time is observed in acidic medium that occurs in vicinity of plant roots. Within this context, preferably, at the step i of the method, the glass blend can be prepared such that it comprises SiO2 in a molar amount of up to 10% with regard to the total amount of materials that constitutes the glass blend. The fertilizer that is obtained in accordance with this measure comprises SiO2 in a molar amount of up to 10% with regard to the total amount of materials that constitutes the fertilizer. In the cases where the compositions of the glass blend of the fertilizer obtained therefrom includes SiO2 within said range, controlled release related dissolving times of up to 90 days are observed. Such duration is considered sufficient for growth/herborization of any plant species. SiO2 used in the step i of the method can be obtained from one or more selected from silica sand, feldspar, blast furnace slag components, or a mixture thereof. Prior to the step i the method can include such step for obtention.
The glass blend that is prepared at the step i of the method according to the present invention, and the glass fertilizer that is obtainable from such glass blend shows an advantageous dissolving behavior even in the case it does not include micronutrients. Yet, preferably, the glass blend that is prepared at the step i of the method according to the present invention, and the glass fertilizer that is obtainable from such glass blend can be prepared such that it contains one or more micronutrients. Examples to the micronutrients include Mn, Mo, B, Fe, Cu and Zn. In the step i of the method, the glass blend can be prepared such that it includes, for example, one or more selected from MnO, MoO3, B2O3, Fe2O3, CuO and ZnO, or preferably, all of said compounds. In the step i, the glass blend can be preferably prepared such that it comprises micronutrients, provided that the combined total molar amount of the micronutrients does not exceed 6%, more preferably does not exceed 1%, of the combined total molar amount of components that constitute the glass blend. For instance, the glass blend can be preferably prepared such that it includes one or more, more preferably all of the following, provided that the combined total molar amount thereof does not exceed 6% with regard to the total amount of materials: MnO in a molar proportion within the range between 0.1% and 1%, MoO3 in a molar proportion within the range between 0.1% and 1%, B2O3 in a molar proportion within the range between 0.1% and 1%, Fe2O3 in a molar proportion within the range between 0.1% and 10%, CuO in a molar proportion within the range between 0.10% and 10%, and ZnO in a molar proportion within the range between 0.1% and 1%. More preferably, the glass blend can be prepared such that it includes one or more, more preferably all of the following, provided that the combined total molar amount thereof is 1% with regard to the total amount of materials: MnO in a molar proportion within the range between 0.1% and 1%, MoO3 in a molar proportion within the range between 0.1% and 1%, B2O3 in a molar proportion within the range between 0.1% and 1%, Fe2O3 in a molar proportion within the range between 0.1% and 1%, CuO in a molar proportion within the range between 0.1% and 1%, and ZnO in a molar proportion within the range between 0.1% and 10%.
In step i, the glass blend includes P, K and Ca amongst macronutrients. In a possible implementation of the method, one or more selected from N, Mg and S can be introduced when preparing the glass blend; the glass fertilizer that is prepared in accordance with this measure can also include one or more components selected from N, Mg and S as macronutrients.
K2O that is used in the step i of the present method can be obtained from any of the compounds selected from potassium sulphate, potassium persulfate, potassium bisulphate, potassium carbonate, or mixtures thereof. The method can include a respective obtention step prior to the step i.
Al2O3 that is used in the step i of the present method can be obtained from any of the components selected from aluminium sulphate, aluminium orthophosphate, calcined alumina, hydrated alumina, feldspar, blast furnace slag, or mixtures thereof. The method can include a respective obtention step prior to the step i.
Na2O that is used in the step i of the present method can be obtained from any of the components selected from sodium carbonate, sodium sulphate, sodium borate, sodium hydroxyde, sodium nitrate, or mixtures thereof. The method can include a respective obtention step prior to the step i.
In a preferred implementation of the present invention, the step i can be implemented such that the glass blend includes one or more of transition metals from the periodic table of elements (in other words, group-B elements or transition elements), for instance, nickel and/or cobalt. Accordingly, the resulting glass fertilizer can also preferably include said one or more transition metals (for instance, Ni and/or Co). It is preferred that the combined total molar amount of said transition metals does not exceed 1% of the total amount of materials that constitute the glass blend.
The melting process in the step ii of the method is preferably performed at a temperature within the range between 1000° C. and 1300° C.
The melting process in the step ii of the method can be performed in a melting pot that is resistant to temperatures of 1000° C. or higher. The material from which the melting pot is formed can be selected from, e.g., alumina or platinum.
The rapid cooling process in the step iii of the method can be performed by, e.g., pouring the glass blend that is molten in the step ii into a water bath that is at room temperature, or, passing said molten glass blend through water-cooled rolls. In the case where a water bath is used in the step iii of the method, granules are obtained; whereas, in the case where water-cooled rolls are used, pieces are obtained in the form of frit.
The method preferably includes subjecting the pieces that are obtained in the step iii, to a grinding process. Said grinding process can be performed, e.g., formation of bulk glass pieces by rapid cooling followed by grinding thereof. Said grinding process is preferably implemented such that the particles have a mean particle size of up to 0.50 mm, more preferably within the range between 0.10 mm and 0.50 mm, and even more preferably within the range between 0.25 mm and 0.50 mm. Said preferred mean particle sizes are, in accordance with their ranking in preferability, considered to be advantageous in view of contact surface between the resulting fertilizer particles and soil. Said mean marticle size can be D50 particle size.
An important portion of chemical fertilizers are washed-off from the soil by irrigation water, and this results in loss of an important portion of nutrients. However, the glass fertilizer according to the present invention shows a slow dissolving behavior, thereby prevents the nutrient losses. The phosphate-based glass fertilizer according to the present invention is completely environmentally friendly, and has a structure that is suitable for containing the macro- and micronutrients that are necessary for the plants throughout the growth period. In addition, the fertilizer according to the present invention continuously releases the nutrients content throughout the plant growth period, thanks to the controlled dissolving behavior thereof. Accordingly, the phosphate-based glass fertilizer provides an effective growth nutrition/growth, thereby increasing the production yield and quality.
A comparative evaluation of the fertilizer according to the present invention with regard to prior art fertilizers can be summarized as follows:
The phosphate-based glass fertilizer proposed within the context of the present invention has shown a successful controlled release behaviour by continuing release for periods of even longer than 90 days, even in neutral pH medium and in acidic pH medium that occurs due to secretion of citric acid from plant roots.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021/009501 | Jun 2021 | TR | national |
This application is the national phase entry of International Application No. PCT/TR2022/050517, filed on Jun. 1, 2022, which is based upon and claims priority to Turkish Patent Application No. 2021/009501, filed on Jun. 9, 2021, the entire contents of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/TR2022/050517 | 6/1/2022 | WO |
