ACTIVATION OF KYZYLKUM PHOSPHORITES IN THE PRESENCE OF SULFUR USING MINERAL SALTS

ABSTRACT

The process of chemical activation of mixtures of phosphorite and sulfur with a molar ratio (7:3) under the influence of potassium chloride, nitrate urea salts was studied. In activated phosphorite samples, as a result of the decomposition of fluorapatite and calcite minerals, the formation of plant-absorbable and water-soluble forms of total P₂O₅, as well as its decarbonation, were observed.

Based on research results, scientific data on the development of a simplified intensive technological scheme for the production of complex fertilizers with fungicidal activity by activating low-grade phosphorites with sulfur and potassium chloride, nitrate-urea salts in the presence of sulfur.

The process of activation of low-grade phosphorites of Kyzylkum phosphorites with sulfur has been studied, and the role, norms of sulfur and the influence of conditions on the transition of the nonabsorbable form of phosphorus to the absorbable one has been identified.

АННОТАЦИЯ

Изучен процесс химической активации смесей фосфорита и серы в мольном соотношении (7:3) под воздействием хлорида калия, нитратно-карбамидных солей. В активированных образцах фосфорита в результате разложения минералов фторапатита и кальцита наблюдалось образование усваиваемых растениями и водорастворимых форм общего P₂O₅, а также его декарбонизация.

На основе результатов исследований научные данные по созданию упрощенной интенсивной технологической схемы получения комплексных удобрений, обладающих фунгицидной активностью путем активации низкосортных фосфоритов с серой и хлорида калия, нитратно-карбамидных солей в присутствии серы.

Исследован процесс активации низкосортных фосфоритов Кызылкумских фосфоритов с серой, а также выявлены роль, нормы серы и влияние условий на переход неусвояемой формы фосфора в усвояемую.

Keywords: Central Kyzylkum phosphorites, sulfur, hydrophilic, hydrophobic, decomposition, phosphorus-sulfur fertilizers.

Ключевые слова: Центрально-Кызылкумские фосфориты, сера, гидрофильные, гидрофобные, разлагающиеся, фосфорно-серные удобрения.

Introduction

One of the effective ways of using low-grade phosphorites is to chemically activate them with salts of mineral acids to obtain slowly acting complex phosphorus fertilizers. Processing of phosphorites with mineral acid salts using non-traditional methods makes it possible to organize the production of local raw materials in places where they are used as phosphorus fertilizers. [1-5].

It is known that the main composition of phosphorites is medium salts that are poorly soluble in water. Therefore, the plant can absorb phosphorus from them with difficulty, only in acidic soil conditions. Obtaining, transporting and using softened (or mechanically activated) phosphorite flour in agriculture is not economically efficient. [6-7].

At the same time, along with protection of plants, feeding with sulfur is one of the urgent problems. Because the amount of sulfur in the soil does not satisfy the normal growth of plants. Sulfur is very vital for the growth and development of plants, and it is one of the macronutrients necessary for plants. If it is not enough, it will lead to a decrease in the quality of the crop and to various diseases in the stages of development of agricultural crops, and the expected harvest at the end of the year will not be achieved. However, the fact that sulfur has a hydrophobic (non-wetting) property reduces its effectiveness and makes it difficult to obtain sulfur-containing chemical preparations. [8-11].

Scientists all over the world, including in Uzbekistan, are looking for low-cost and resource-efficient ways of obtaining phosphorus fertilizers from unenriched and low-quality phosphorites. In this regard, one of the hot scientific researches issue is the development of new types of complex fertilizers by activating phosphorites on the basis of chemical, mechanical, mechanochemical, thermal and bacterial [12-18].

Therefore, the development and implementation of specific resource-efficient technologies for obtaining phosphorus-sulfur and nitrogen-phosphorus-sulfur complex fertilizers, which contain substances that fight against disease-causing insects along with phosphorus nutrients, are one of the most urgent issues of today. is one. The use of these phosphorus-sulfur fertilizers simultaneously provides plants with nutrients and protects them from various diseases.

Experimental section

The presence of carbonate mineral - calcite in Central Kyzylkum phosphorites in three different forms, i.e., "ecdocalcite", "enzocalcite" and phosphate minerals. allows it to break down easily and quickly.

Based on samples of Kyzylkum phosphorite, the process of activation of phosphorite raw materials with the help of sulfur was studied in order to obtain complex fertilizers with insecticidal properties. For this purpose, samples of phosphorite were mixed with sulfur (10:0)-(1:9) by weight and thoroughly mixed in a ball mill for 15-30 minutes in laboratory conditions. The amount of different states of P₂O₅ (total, plant-absorbable and water-soluble) in the obtained mixtures was chemically analyzed using certain standard methods [19-20]. Also, the degree of hydrophilization (wetting) of sulfur in the mixture, the degree of decarbonization, and different forms of the amount of CaO were determined.

In the course of scientific research, phosphorite samples were mixed with sulfur (7:3) by weight, and mineral salt solutions with a concentration of 2% to 20% and 2, 5, 10 and 20 g A mixture was prepared from samples of non-enriched phosphorite flour (0.35 g - 3.53 g P₂O₅), low-quality phosphorite (0.26 g - 2.68 g P₂O₅). The activation process was carried out at room temperature for 30 minutes with continuous stirring of phosphorite and salt solution.

Scientific research experiments are conducted in samples based on the following composition (weight %) of phosphorite in the Central Kyzylkum basin: unenriched phosphorite flour P₂O₅ - 17.65; CaO – 44.57; MgO – 1.73; CO₂ – 15.25; P₂O₃ – 2.53; SO₃ – 4.42; F – 2.32; H₂O – 1.15 and P₂O₅ of low-quality phosphorite ore – 13.94; CaO – 43.78; MgO – 2.1; CO₂–19.1; P₂O₃ – 3.26; SO₃ – 2.10; F – 0.42; H₂O – 1.17.

The pH values ​​of the initial medium of the activating salt solutions and the medium of the phosphorite-recycled, neutralized fertilizer suspension were determined using a Mettler Toledo Five Easy F20. The content of the main nutrients in the complex phosphorus fertilizer obtained by processing phosphorites, that is, different forms of phosphorus anhydride (total, water-soluble, plant-absorbable part), nitrogen, calcium oxide, carbon dioxide and moisture Chemical analysis was performed using standard methods.

Results and discussion

It is known that sulfur is a substance in a hydrophobic state that does not mix with water, and phosphorite samples have a positive effect on its degree of hydrophilicity. Research has shown that when up to 20% sulfur is mixed with unenriched and low-quality phosphorite flour, it becomes completely hydrophilic.

Because sulfur loses its surface activity property in the presence of air oxygen and moisture in the process of interaction with phosphate mineral. The composition of phosphorite and sulfur interprocessed samples was investigated by some physical research methods (Fig. 1- and Fig. 2).

Figure 1. IR spectrum of a sample obtained in a 7:3 ratio of phosphorite and sulfur

Figure 2. Elemental analysis of a sample taken in a 7:3 ratio of phosphorite and sulfur

The results of the research presented above show that phosphorite samples are activated in the presence of sulfur. In order to further increase the amount of plant-absorbable phosphorus in phosphorite, the influence of the concentration and standards of potassium chloride solutions in the mixture was studied. The results are presented in Table 1 and Table 2.

Research shows that 2 to 20 grams of phosphorite flour activated with potassium chloride solutions with a concentration of 2% to 20% (medium pH=5.5-6.1) contains 8.82% of total phosphorus and 19.7% of total phosphorus. from 40.0% to plant absorbable P₂O₅ and from 0.68% to 4.37% water-soluble P₂O₅. The degree of decarbonization of raw materials will increase from 13.3% to 40.1%.

         The results of activation processes of low-quality phosphorite under the influence of potassium chloride solutions are practically close to those of non-enriched phosphorite flour. Phosphorites were processed in a solution of potassium chloride, and samples of complex fertilizers containing potassium and phosphorus nutrients were obtained. The recommended product based on phosphorites activated with potassium chloride contains potassium oxide from 4.70% to 47.1%.

Table 1.

Activation of a mixture (P₂O₅) with a mass ratio of 7:3 between non-enriched phosphorite flour and sulfur under the influence of potassium chloride solutions

Table 2.

Activation of low-quality phosphorite and mixture (P₂O₅) with a mutual mass ratio of sulfur 7:3 under the influence of potassium chloride solutions

It has been proven on the basis of research that it is possible to activate low-grade Central Kyzylkum phosphorites with mineral salts and obtain nitrogen, phosphorus and potassium fertilizers in the required ratio for agriculture.

Chemical interaction of phosphorites with urea nitrate is intense. During the processing of raw materials with salt, as a result of the release of gases (CO₂, HF), a small-scale strong foaming phenomenon was observed. Due to the released heat, the temperature of the reaction rises to 40-50 ºC.

In activated phosphorite samples, as a result of the decomposition of fluorapatite and calcite minerals, the formation of plant-absorbable and water-soluble forms of total P₂O₅, as well as its decarbonation, were observed. Activated raw materials with nitrate-urea solution are almost completely decomposed, and the obtained experimental results are presented in Table 3 and Table 4.

75.9% of 8.82% of total P₂O₅ contained in 2 grams (0.353g P₂O₅) of phosphorite flour activated for 30 minutes under the influence of 2% solution of urea nitrate (acidic medium pH=1.0) is absorbed by plants and 36 7% is in water-soluble form. In this process, the degree of decarbonation of raw materials is 58.0%. As the concentration of urea nitrate increases, the degree of decomposition of phosphorite increases.

Table 3.

Activation of unenriched phosphorite flour and sulfur with a mass ratio of 7:3 (P₂O₅) under the action of urea nitrate solutions

The fraction of plant absorbable P₂O₅ in 2 grams of activated phosphorite flour increased from 83.3% to 96.2% when the urea nitrate concentration increased from 5% (pH=0.75) to 20% (pH=0.50). up to, and the part of P₂O₅ soluble in water increases from 52.4% to 63.7%.

When comparing the above results with the 2% solution of raw materials, the plant-absorbable form of P₂O₅ in activated phosphorite increases by an average of 1.17 times, and the part of water-soluble P₂O₅ increases by an average of 1.59 times. In these processes, as the solution medium changes from pH=0.50-0.75 to pH=1.0-2.9, the degree of decarbonation of phosphorite flour increases from 69.4% to 87.2%, the resulting mixed medium and it is acidic. As the amount of phosphorite flour increases from 5 grams to 20 grams (from 0.882 g to 3.53 g P₂O₅), the degree of decomposition of raw materials decreases. For example, after the activation of 5 to 20 grams of phosphorite flour under the influence of a 2% solution of nitrate urea, the part of P₂O₅ absorbed by plants in its content is from 59.5% to 11.4%, and the part of P₂O₅ soluble in water is 19, It will decrease from 7% to 3.87%. That is, compared to the activation process of 2 grams of phosphorite flour in a 2% solution, the proportion of plant-absorbable P₂O₅ in their content is 1.32 and 6.90 times, and the proportion of water-soluble P₂O₅ is 1.86 and 9.50 times, respectively. decreases. These results are also observed in 5%

Table 4

Activation of low-quality phosphorite flour and sulfur with a mass ratio of 7:3 with urea nitrate solution

to 20% urea nitrate solutions. Plant-absorbable P₂O₅ content of 5 to 20 grams of non-enriched phosphorite flour treated with 5% to 20% solutions of urea nitrate is 70.3% to 19.3% in 5% solution and 19.3% in 10% solution and it changes from 78.9% to 31.2%, in 20% from 86.3% to 37.7%. Also, in this process, it was observed that the level of decarbonization of phosphorite flour activated with 2% solution of urea nitrate decreased from 45.2% to 9.97%.

Indicators of the degree of decomposition of low-quality phosphorite under the influence of urea nitrate are 1.07-1.08 times lower than those of non-enriched phosphorite flour.

The activation of phosphorites under the influence of urea nitrate solution can be explained as follows. Dissociated nitrate urea in aqueous solution forms free nitric acid. As the concentration of urea nitrate in the solution increases, the values ​​of the medium decrease from pH=1.0 to pH=0.5, and its acidity increases further. As a result of the reaction with phosphorite, the produced nitric acid decomposes the minerals contained in the raw material. As the amount of phosphorite increases, the concentration of urea nitrate (H⁺ and NO₃^-) decreases, and its activation level decreases.

Samples of complex phosphorous fertilizers were obtained by reprocessing phosphorites with nitrate-urea solution. As the soluble form of phosphorus anhydride increases in its composition, the amount of nitrogen also increases. For example, from 2 to 20 grams of phosphorite flour activated with a 2% solution of urea nitrate, the following ratio of phosphorite and nitrogen in the following ratio N:P₂O₅ =1:(0.5-5.0) contains nitrogen from 3.12% to 17.4%. will change. When the solution concentration changes from 5% to 20%, the amount of nitrogen in the product increases from 6.88% to 32.9%. So, as it can be seen from the results, it is possible to obtain an effective fertilizer mixture with the required ratio of nutrients when phosphorite is activated with urea nitrate.

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