RESEARCH ON OBTAINING GRANULAR CALCIUM NITRATE FROM LOCAL RAW MATERIALS

ABSTRACT

The article shows the results of the geological and chemical study of local deposits for the production of granular calcium nitrate from local raw materials and the analysis results for the production of granular calcium nitrate from them. The processes of obtaining granular calcium nitrate, first by liquid and then by evaporation of liquid calcium nitrate, were studied by reacting it with concentrated nitric acid (49.21%) with waste from various local mines and samples taken from idle mines. Calcium nitrate liquefaction with 99.0% yield was obtained based on 93.15% pure Zarbant mine marble (107.52 g) with 49.21% nitric acid (256 g) in a stoichiometric ratio of its calcium carbonate content. Then, a 12.4% aqueous ammonia solution was added to it until the pH of the product was in the range of 6.78-7.0 and the specific gravity of the liquid was 1.85.

АННОТАЦИЯ

В статье приведены результаты геолого-химического изучения местных месторождений для производства гранулированной селитры кальция из местного сырья и результаты анализа для производства гранулированной нитрата кальция из них. Изучены процессы получения гранулированной кальциевой селитры сначала жидким, а затем упариванием жидкой кальциевой селитры путем взаимодействия ее с концентрированной азотной кислотой (49,21%) с отходами различных местных шахт и пробами, взятыми из простаивающих рудников. Нитрат кальция ожиженным с выходом 99,0% получен из расчета на 93,15% чистоту мрамора Зарбанта (107,52 г) с 49,21% азотной кислоты (256 г) в стехиометрическом соотношении содержания в нем карбоната кальция. Затем к нему добавляли 12,4% водный раствор аммиака до тех пор, пока рН продукта не находился в пределах 6,78-7,0, а удельный вес жидкости не составлял 1,85.

Keywords: local raw materials, nitric acid, decomposition coefficient, temperature. Nitrogen loss, yield.

Ключевые слова: местное сырье, азотная кислота, коэффициент разложения, температура, потери азота, урожайность.

INTRODUCTION

As of 2023, the population of Uzbekistan has exceeded 36 million. In 2019, the total volume of agricultural, forestry and fishery products in our republic increased by 102.5% compared to 2018, and in 2020, which is a serious testing period for food safety, 6.5 million about a ton of grain, 3 mln. more than tons of cotton, 21 thousand tons of cocoons, 22 mln. tons of fruits and vegetables, 2.5 million tons of meat and 11 million tons of dairy products were grown [1]. According to the State Statistics Committee of the Republic of Uzbekistan, on June 1, 2021, the number of large cattle in the republic reached 12,953 thousand. However, it should be noted that at present, the number of cattle per capita is 0.39, the production of dairy products is 315 liters, and meat is 41 kg. According to the standard of established medicine, the supply is 1.7 and 2.0 times less [2].

Meat consumption compared to the total population is 2.5 million. more than a ton. For example, 1.9 million during the 9 months of 2021. tons of meat was produced. According to the reports of the Statistics Committee, 27,600 tons of meat were imported to Uzbekistan in January-November 2021. That is, compared to the same period of 2020, meat import increased by 8.4 thousand tons. The main part of the meat comes from Belarus (18.7 thousand tons), Kazakhstan (4.2 thousand tons), Ukraine (2.6 thousand tons), Russia (629 tons) and Moldova (660 tons). fainting [3]. But this volume of meat products is not enough for more than 36 million inhabitants of the republic. One of the reasons for not fully meeting the demand is the lack of feed for livestock, poultry and fisheries.

According to the Food and Agriculture Organization (FAO), the number of cattle has been increasing in the world in recent years. In 2017, the number of cattle was 1.7 billion. formed, this figure will increase to 1.8 billion by 2020. increased by the amount. In a similar situation, the number of poultry and sheep increased during the studied period [4]. According to the data of the Organization for Economic Cooperation and Development, in 2020 the annual world consumption of poultry meat will be 133.35 million. tons, which is 15,102 kg of meat per capita. This situation, in turn, requires an increase in the production of feeds, especially phosphate feeds [6]. This will increase livestock and poultry production, especially in European countries with limited land use, and at the same time accelerate the demand for nutritional supplements to feed growing cattle and poultry. The largest producers of feed phosphates in the world are The Mosaic Company, Eurochem, Potash Corp, PhosAgro and OCP Group. According to the forecast, the annual growth of the nutritional phosphates market (2022-2027) is 4.5% on average.

The following issues should be noted in use

1. It is not suitable to apply to rice fields because calcium nitrate belongs to nitrate nitrogen and it is easy to lose it with water.

2. It cannot be mixed with fresh manure and compost, because the organic acid formed during the fermentation process of the fertilizer converts calcium nitrate into nitric acid and causes the fertilizer to lose its nutrients. Calcium and its compounds are widely used in the chemical, metallurgical, petrochemical, food, pharmaceutical and construction sectors of the country's economy.

Calcium is the second most abundant element in seawater and the fifth most abundant element in the earth's crust, accounting for approximately 3.38% of its composition [7]. Russia is one of the world's leading producers of calcium nitrate, producing 900,000 tons of calcium and its compounds per year [8;9].

According to the estimates and calculations of the CHEMANALYST market analysis group, the world calcium nitrate market is expected to reach 9.7 million tons of sales in 2023, and 15.6 million tons of sales in 2032 [10].

The shares of supplying countries in the market of calcium nitrate change every year. The ranking of supplier countries is also changing.

Table 1.

 Share of countries selling calcium nitrate in the world   

Among the supplying countries in the world market of calcium nitrate estimated by CHEMANALYST in 2023, excluding Russia, the first places are: Israel with a 13% share, Norway with a 11.5% share. According to the results of the analysis, Japan, China, the USA, the Netherlands, Canada and other countries are among the supplier countries. analysts see Russia as the leading supplier of calcium nitrate.

All over the world, the source of calcium salts is limestone, dolomite, marbles, which contain a large amount of calcium [11].

Extraction of calcium nitrate from calcium resources is accompanied by a long process, where a very strong foaming occurs. If the amount of carbon dioxide in the composition is significant, the processing of the mineral takes more time. Marble is abundant in nature and dolomite deposits are very good, but high calcium oxide content is more common in marbles. Then minerals with a CaO content of more than 52% are more promising. [12]

Methods and materials. Calcium in marbles is mainly bound to carbonate, and accompanying elements such as iron, aluminum, magnesium and fluorine are found in small but small amounts...

Usually, the technology for obtaining calcium nitrate from marble and limestone is based on acid-hydrometallurgical methods, obtained at temperatures of 25-30 ° C. [13]

First, we analyzed chemically and geologically the base of local raw materials and their waste, as well as limestone, marble and calcium raw materials in neighboring countries.

We received the following information.

Figure 1. Composition of raw materials

After analyzing the results of this analysis, we selected raw materials that would be acceptable to us. In the key stages of our work, we determined the dispersion composition of selected raw materials.

Table 3.

 "Italy" brand calcium carbonate, Zarbant marble, Ghazgon marbles and dispersed components of Bulagboshi and Kuvasoy limestones

After determining the dispersed composition of the selected local raw materials, we determined the chemical composition of the raw materials. In this case, we determined calcium oxide, carbon dioxide, magnesium oxide, iron oxide, fluorine, aluminum oxide, sulfur oxide of raw materials.

Table 4.

Chemical composition of "Italiya" brand calcium carbonate, Zarbant marble, Gozgon marbles and Bulagboshi, Kuvasoy limestones

Results and discussion. After analyzing the obtained results, Zarbant marble waste in Samarkand region was accepted as the most acceptable option. At the next

stage, we treated Zarbant mineral with nitric acid in different proportions. A marble sample was added to a glass reactor with nitric acid and mixed with a screw mixer at a speed of 250-300 revolutions to carry out acidification, that is, decomposition. The temperature of the process is regulated by a thermostat. After completion, the reaction mass is filtered under vacuum (0.2 atm.) in a Buchner funnel. Calcium nitrate liquefaction with 99.0% yield was obtained based on 93.15% pure Zarbant mine marble (107.52 g) with 49.21% nitric acid (256 g) in a stoichiometric ratio of its calcium carbonate content. Then, a 12.4% aqueous ammonia solution was added to it until the pH of the product was in the range of 6.78-7.0 and the specific gravity of the liquid was 1.85. The reason is that the purity of the marble brought from the Zarbant mine is up to 93% and the yield of the reaction is up to 99%, so there is a small amount of free nitric acid in the calcium nitrate liquid. After neutralizing this nitric acid with ammonia solution, it was found that 4.1% ammonium nitrate is also formed in the product.

Table 4.

Results

In the next step, the obtained calcium nitrate was ammonified in two different concentrations. Negative and positive results were recorded.

Ca(NO₃)₂*4H₂O

Figure 2. Composition of the finished product

Conclusion

The processes of obtaining granulated calcium nitrate based on stoichiometric decomposition of 49.21% of Nitric acid at the rates of 90, 95 and 100% of CaCO₃ were studied.

The optimal concentration of nitric acid in the production of granulated calcium nitrate is 49.21%. In this case, the composition of the product will be as follows (wt.%): N_tot-14.9, N_am - 1

CaO _total -25.9 CaO _wat -25.8

The concentration and speed of nitric acid affected the decomposition process of marble from the Zarbant mine. Studies were carried out over a wide concentration range of 30-50% and at a stoichiometric rate of 90-110% at 25-30°C for 3 hours. 100% of its constant speed, a temperature of 25-30 ° C and a decomposition time of 1-2 hours Kras., CaO, and CO₂ 90.05 increase in the concentration of nitric acid; 91.53; 48.13; respectively 98.9%.

An increase in the stoichiometric norm of nitric acid from 100 to 110% and its concentration from 49.21%, Kraz., CaO, and CO₂ from 98.9% to 99.2% within 2 hours.At the same time, the optimal condition turned out to be a nitric acid rate of 110% stoichiometry at a concentration of 49.21%, a temperature of 25-30 ° C and a decomposition time of 2 hours, in which Kraz. CaO was 99.2%.

The resulting granular calcium nitrate fully meets the requirements of GOST 4142-77-80. They can be used in agriculture.

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