SK9827Y1 - Liquid fertilizer - Google Patents

Abstract

Liquid fertilizers containing potassium and sulfur are disclosed. The fertilizers are characterized by the fact that they comprise dipotassium sulfite K2SO4. The products are characterized by high phase stability, usually do not contain chlorine, and they can be mixed with the most of fertilizers and plants protection products. The process for production of the products is not demanding and enables efficient recovery of sulfur dioxide emissions from industrial emissions.

Description

The field of technology

The solution concerns liquid fertilizers containing potassium and sulphur.

Current state of the art

It has long been known that sulfur is an important plant nutrient. In the past, sulfur was included among the so-called secondary nutrients, where it formed one group together with calcium, magnesium and iron. However, it has now been clearly established that this nutrient should be among the essential plant nutrients - along with nitrogen, phosphorus and potassium (Hester, B. - "Sulphur-The Fourth Major Nutrient, Solutions 44-50, Nov. - Dec. 1979 ).

Even in our soil and climate conditions, it has been confirmed that several plants take more sulfur than phosphorus from the soil, even though the total amounts of sulfur in the soil are lower than half the phosphorus reserves.

Sulfur deficiencies are caused by the increasing yields of agricultural crops, the use of industrial fertilizers that often do not contain sulfur (e.g. lower use of simple superphosphate as a source of phosphorus), the limitation of the use of fossil fuels, the increasing pressure to reduce industrial exhalations, the decreasing range of use of pesticides (fungicides and insecticides) containing sulfur and also by the constantly decreasing content of organic content in soils.

Protein synthesis in plant organisms cannot take place if plants cannot receive the necessary amount of sulfur in addition to nitrogen and vice versa. From the above, it follows the dependence between nitrogen and sulfur nutrition of plants, as well as the insufficient use of one of the plant nutrients in question, if the plant is not allowed to receive an adequate amount of the second - deficient nutrient. It has been proven that in plants with a sulfur deficiency, the concentration of soluble proteins significantly decreased and, on the other hand, an increased content of undesirable nitrates and nitrites was determined in them (Mortvedt. J.J. - "Identifying and correcting sulfur deficiencies in crop plants, Crop and Soils Magazine 11-14, June-July 1981).

It has been scientifically proven that sulfur is needed by plants to the same extent as phosphoric acid (eg Hofman, E. 1959). It is remarkable that, even though the importance of sulfur fertilization was clearly demonstrated in our conditions in the past, clearly demonstrable results of agronomic research remained very little used in our agricultural practice in the past. For the practical documentation of the above, at least two statements of the workers of the former VŠP in Nitra can be quoted: "In the conditions of field trials, we found that new varieties of winter wheat are more demanding on sulfur than on phosphorus., or in another place "Spring barley reacts sensitively to sulfur fertilization, more sensitive than potassium. (Ivanič, J. - Benko, V. - Report of the VIII Slovak Seminar on the Rational Use of Industrial Fertilizers, Michalovce, 27 - 29 January 1982 - collection of lectures p. 150).

Sulfur also plays an important role in the formation of chlorophyll and compounds resulting from photosynthesis, the conversion of carbon dioxide and water under the influence of solar energy into hydrocarbons. The importance of sulfur in living organisms is generally known. Sulfur is part of every cell and is found in amino acids (methionine, cysteine, cystine).

It follows from the above that the lack of sulfur in a plant-acceptable form negatively affects not only yields, but to a significant extent also the quality of plant production.

Professional, mainly American literature states that sulfur is essential for achieving the quality parameters of cereals. Sufficient plant-acceptable sulfur is essential to achieve the required quality of bread wheat. Wheat grown with a lack of sulfur has a low quality - the flour is doughy, with a high ash content, poor grindability, low gluten content and overall unsuitable "bakery properties". Several professional studies prove that a high level of applied nitrogen without a corresponding dose of sulfur significantly reduces the quality of bread flour.

Professional literature recommends ensuring that the sulfur content in the soil does not fall below 22.5 kg S per hectare. In connection with the application of fertilizers, it is necessary to ensure that the ratio of nitrogen to sulfur is at least 5:1 and the ratio of phosphorus to sulfur (P2O5/S) is at least 3:1. It has been proven that the presence of sulfur positively affects the acceptability of phosphorus, especially by young plants. and also helps maintain phosphorus in plants in an acceptable form - it protects it from retrogradation.

In countries with an advanced level of production and use of industrial fertilizers, the following substances are currently used as sources of plant-acceptable sulfur: elemental sulfur, polysulfides, ammonium sulfate, sulfates, thiosulfates, calcium sulfate - gypsum, simple and enriched superphosphate, magnesium sulfate (so-called Epsom salt ), magnesium-potassium sulfate, potassium sulfate, iron sulfate (so-called green rock) and sulfates of metal trace elements - copper, zinc and manganese. Even though the mentioned substances enable the fertilization of plants, only some of them can be effectively used for foliar nutrition.

Especially at the end of the twentieth century, even in our conditions, the production and use of liquid fertilizers containing, in addition to other biogenic elements, also sulfur in a plant-assimilable form gradually expanded. In addition to special liquid fertilizers, where the total sulfur content was often only very low, the use of liquid fertilizers based on ammonium sulfate (SAM, SADAM), magnesium sulfate and highly concentrated multi-component liquid fertilizers based on sulfates, the so-called thiosulfates.

In this context, it is particularly gratifying that last year the production of liquid nitrogen-sulfur solution fertilizer of the type: 12-0-0+26 S from sulfur off-gases of the petrochemical industry began in Slovakia. The original technology for the production of solution liquid fertilizers based on sulfates - thiosulfates, as well as the verification of their properties and effectiveness in the conditions of our agricultural practice, was paid considerable attention in the early eighties in the former Research Institute of Agrochemical Technology in Bratislava (AO No. 227137).

In connection with the production of liquid agrochemicals serving plants as a source of sulfur, primarily potassium sulfates and polysulfides are currently used. The use of potassium sulfates in the preparation of solution-type liquid fertilizers is considerably limited due to their relatively low solubility in water. Potassium polysulfides are mainly used in connection with the production of fungicidal and acaricidal preparations.

Abroad, concentrated (approx. 50%) aqueous solutions of potassium sulfate - thiosulfate, K2S2O3 (0-0-25+17S) are also used as liquid sulfur-potassium fertilizers.

The production of a similar liquid fertilizer was, in the eighties of the last century, semi-operationally managed also in the already mentioned VÚAgT in Bratislava. The greater application of this otherwise very high-quality liquid fertilizer in our agricultural practice is currently hindered by its limited availability, relatively demanding technological production process, higher price and also lower phase stability compared to liquid fertilizers prepared on the basis of ammonium salt.

Recently, attention has also been paid to sources of organically bound sulfur. In this context, it is possible to mention e.g. alkylsulfur compounds and from them e.g. dimethyl sulfoxide (DMSO), as an effective source of sulfur that quickly penetrates through cell walls, while the sulfur compound in question can be considered a substance that has a natural origin and is part of the sulfur cycle in nature (ÚV 6642).

The essence of the technical solution

Even though the liquid fertilizers currently produced and used in practice significantly help in ensuring the nutrition of plants with sulfur, their frequent disadvantages include either a relatively low sulfur content, inappropriate physico-chemical properties (phase stability at low temperature), or a relatively complex process of their preparation and price difficulty.

The mentioned disadvantages preventing a greater expansion of the production and use of liquid fertilizers containing potassium and sulfur are made possible by the products in terms of this solution. It is characteristic of these liquid fertilizers that they contain dipotassium sulfite - K2SO3. By studying the phase equilibria in the binary system: K2SO3 - water, it was found that aqueous solutions of dipotassium sulfite are characterized by extremely high phase stability (eutectic: 51% K2SO3 at a temperature of minus 45.5 °C!). The established fact makes it possible to obtain solution liquid fertilizers containing potassium and sulfur of similar and often even higher quality, as in the case of the already mentioned products, by a much simpler and therefore cheaper technological process. It was found that the mentioned system enables the preparation of solution-type liquid fertilizers, which are characterized by their high phase stability (problem-free storage even at temperatures significantly below the freezing point of water), while these can contain around 30 parts by weight of potassium in 100 parts by weight of fertilizer (as K2O) and about 10 parts by weight of sulfur (as S). With an unusually high specific gravity - the density of concentrated aqueous solutions of dipotassium sulfite (d = approx. 1,500 kg/m ³ at approx. 20 °C), potassium-sulfur solution liquid fertilizers can, depending on the solution, contain more than 374 g of sulfur (as SO3) and approx. 450 g of potassium (as K2O) in chlorine-free form per liter. Despite the unusually high content of biogenic elements in the products in question, their handling and storage properties are significantly better than the majority of liquid fertilizers of a similar type produced and used today.

The preparation of liquid fertilizers in the sense of a solution can be simple - absorption of sulfur dioxide in aqueous solutions of suitable potassium alkali in terms of greatly simplified reaction schemes:

KOH + SO2 ^ K2SO3 + H2O K2CO3 + SO2 ^ K2SO3 + CO2.

When preparing liquid fertilizers based on sulfate - potassium thiosulfate, the use of elemental sulfur must usually be considered. The process can be expressed, in the case of the use of hydroxide, by a simplified reaction scheme as follows:

KOH + SO2 + S ^ K2S2O3 + H2O.

In order to achieve the desired yield and kinetics of the process, elemental sulfur must be present in at least a slight excess in the reaction medium. If the solution nature of the final liquid fertilizer product is to be preserved, it is necessary to separate the unreacted elemental sulfur from the reaction mixture. A significant advantage of the liquid fertilizer production process in the sense of the solution is the complete exclusion of the handling of the solid reaction component, the process works exclusively with solutions and not suspensions, while the technology does not have to use any of the methods of separating unreacted solid particles from the product. Considering these facts, the technological device can be significantly simpler, and therefore cheaper.

Liquid fertilizers containing potassium and sulfur according to the solution can be mixed with most fertilizers and preparations used for plant protection and also allow the preparation of other special multi-component mineral and organo-mineral fertilizers.

Liquid fertilizers in the sense of the solution are intended for all methods of soil and plant nutrition used in practice, but they are especially suitable for fertilizing plants by spraying their above-ground parts, on the so-called foliar application.

Implementation examples

The given examples clarify and document the solution in question, but in no way limit the claims for its protection.

Example 1

In order to prepare a sample of solution liquid fertilizer containing potassium and sulfur, 510 g of crystalline dipotassium sulfite, K2SO3, was dissolved in 490 ml of water. 1,000 g of a practically clear, colorless solution, with a weakly alkaline chemical reaction, containing more than 30 wt. % K2O and 10.3 wt. % sulfur (as S). The prepared product retained its original solution character even after several months of storage in the freezer compartment of the refrigerator (approx. -18 °C).

Example 2

In order to verify the possibility of continuous preparation of solution liquid fertilizer containing potassium and sulfur according to the solution, the technology was verified using an absorption tower (filled with Berl saddles and Raschig rings). Circulation of the absorbent was ensured by a pump, while a tubular cooler placed behind the pump was used to remove reaction heat. An approximately 45% aqueous solution of potassium hydroxide was dosed into the upper part of the tower as an absorbent, and a model gas mixture consisting of air and sulfur dioxide was fed into its lower part - under the filling. The absorbent flowing down after the filling reacted with sulfur dioxide according to the scheme:

2KOH + SO2 ^ K2SO3 + H2O.

The dosage of potassium hydroxide was adjusted according to the chemical reaction (pH) of the solution continuously removed from the reservoir located under the absorption tower. By maintaining the pH of the draining solution in the range of 7.5 - 9.0, the desired product was obtained according to the solution, which had the character of a practically clear, colorless solution. Specific gravity - the density of the solution at room temperature fluctuated between 1.46 and 1.50 g/cm ³ . The composition of the prepared liquid fertilizer corresponded to the formula: 0-0-30+10S.

Example 3

When verifying the continuous preparation of liquid fertilizer in the sense of the solution, it was worked in a similar way and using identical equipment as in example 2, while an aqueous solution of potassium carbonate - potash was used as an absorbent according to the scheme:

K2CO3 + SO2 ^ K2SO3 + CO2.

Example 4

In the laboratory preparation of liquid fertilizer containing potassium and sulfur according to the solution, the procedure was followed by first mixing 77.97 parts by weight of an aqueous solution of potassium hydroxide containing 49.5 parts by weight. % KOH, with 6.75 parts by weight of water prepared a dilute aqueous solution of KOH. A total of 22.03 parts by weight of sulfur dioxide from a pressure bottle equipped with a reducing valve was added gradually to the thus prepared aqueous solution of potassium hydroxide, with constant stirring, through a glass capillary reaching below the level of the hydroxide, through a rotameter.

In this way, more than 106 parts by weight of a clear, colorless solution containing approx. 50 parts by weight were prepared. % of dipotassium sulfate, which was characterized by extremely high phase stability (clearing point, approx. - 45 °C).

Example 5

In order to assess the miscibility of liquid fertilizers containing potassium and sulfur according to the solution with nitrogen fertilizer type 30-0-0 and nitrogen-phosphorus liquid fertilizer type 8-24-0, the following mixed solutions were prepared.

Designation of the sample: Amount of component - basic liquid fertilizer (g) Nitrogen solution type: 30-0-0 Potassium-sulfur fertilizer type: 0-0-30+10S Nitrogen phosphate fertilizer type: 8-24-0 1 50 50 - 2 80 20 - 3 15 85 - 4 90 10 - 5 - 90 10 6 - 70 30 7 - 50 50

The prepared mixed solutions did not show any change after 24 hours of their storage at room temperature.

Industrial applicability

It is typical for liquid fertilizers containing potassium and sulfur by solution that they contain dipotassium sulfite - K2SO3. Fertilizers with a high content of potassium (approx. 30 wt.% K2O ) and sulfur (approx. 10 wt.% S) can be prepared on the basis of the dipotassium sulfite - water system. The products in question are characterized by high phase stability, usually do not contain chlorine and can be mixed with most fertilizers and preparations intended for plant protection.

The production process of these fertilizers is undemanding and enables efficient recovery of sulfur dioxide emissions from industrial gases (for example, desulfurization of exhalations from oil processing processes, pulp and paper industry, etc.).

Liquid fertilizers in the sense of the solution are intended for all methods of fertilizing soil and plants, but they are especially suitable for fertilizing plants by spraying their above-ground parts, on the so-called foliar application.

Claims (3)

CLAIMS FOR PROTECTION 1. Liquid fertilizers containing potassium and sulfur, characterized by the fact that they contain dipotassium sulfite - K2SO3. 5 2. Liquid fertilizers containing potassium and sulfur according to claim 1, characterized in that v 100 parts by weight contain 30 parts by weight of potassium (as K ₂ O) and 10 parts by weight of sulfur (as S). 3. Liquid fertilizers containing potassium and sulfur according to claim 1, characterized by the fact that they have the character of a true solution.