THE PRODUCTION OF SODIUM SULFATE ON THE BASIS OF NATURAL RAW MATERIALS AND STATISTIC INFORMATION BY EXPORTING IT

One of the main directions of the economic development of the Republic of Uzbekistan is the development of natural resources, their integrated use and the creation of competitive import-substituting products based on local raw materials. Such products include sodium sulfate which the need for it is constantly growing.

Uzbekistan has large reserves of sodium sulfate (mirabilite, tenardite, astrahanite) which was found in the salt sediments of the Aral Sea: the place of sediments are in Akkaly, Kushkanatau and Tumryuk in the Republic of Karakalpakstan. Tumryuk field of mirabilite is one of the main raw materials sources of sodium sulfate, characterized by a minimum content of impurity salts of halite, epsomite and gypsum.

The scientific importance of obtaining sodium sulfate conversion method includes the fact that carried out research was the scientific base for the creation of technology for obtaining glauber salt in medical purpose, sodium sulfate and ammonium chloride from local raw materials - natural mirabilite of the Tumryuk field, as well as the process of conversion of natural sodium chloride with ammonium sulfate. Scientific significance is also due to the results of studying the solubility and nature of solid phases in a quaternary mutual system.

2Na⁺, 2NH₄⁺ // 2Cl^-, SO₄^2- – H₂O and its constituent triple system

2NH₄⁺ // 2Cl^-, SO₄^2- – H₂O

Obtaining tradable sodium sulfate from local raw materials is purposefully to carry out according to the scheme which is providing for salt dissolution, removal of insoluble residue, crystallization of sodium sulfate decahydrate from the clarified solution and separation of the product from the solution obtained by melting sodium sulfate decahydrate by evaporation. Herewith, it is important to establish the kinetic parameters of the leaching of natural salt.

The technological base for the production of sodium sulfate by the conversion of sodium chloride with ammonium sulfate is based on the physicochemical properties of the quaternary mutual water system from sodium and ammonium chlorides and sulfates and its constituents of ternary systems.

In this connection, in order to justify the process of conversion of sodium chloride with ammonium sulfate at elevated temperatures, the isothermal method at 100 ° C was studied by the triple system

(NH₄)₂SO₄–NH₄Cl–H₂O and quaternary system

2Na⁺, 2NH₄⁺ // 2Cl^-, SO₄^2- – H₂O.

The solubility diagram of the triple system at 100 ° C consists of two branches of solid-phase crystallization of sulfate and ammonium chloride (Fig. 1). The ammonium sulfate crystallization branch is larger than ammonium chloride.

Figure 1. The diagram of solubility the system of ammonium sulfate-ammonium chloride in water at 100° C

In the studied system education new compounds were not observed. The peculiarity of the isotherm is that the components of the system have a mutual salting action on each other. Due to the good solubility in this system, ammonium chloride has a greater salting action on ammonium sulfate than ammonium sulfate on ammonium chloride.

The process of conversion of sodium chloride with ammonium sulfate in a solution which its containing is 16.75%, was researched for the extradition of practical recommendations for the production of sodium sulfate and ammonium chloride.

Na₂SO₄, 1,49 % NaCl, 21,48 % NH₄Cl and 60,28 % H₂O.

The research was carried out at temperatures of 60, 80 and 100° C and the duration of the experiments was 15-150 minutes.

Determination of the order of the reaction of sodium chloride with ammonium sulfate showed that it is satisfactorily described by a known first-order kinetic equation. This is confirmed by the fact that the conversion rate constant remains practically constant for each temperature.

The values of the pre-exponential factor k₀ and the apparent activation energy (E) were found by using the mathematical processing of the experimental data. The Arrhenius equation takes the form: k=54120·е^{-10802,28/(R·T)}.

The speed constants of the conversion of sodium chloride with ammonium sulfate at various temperatures in the interval 40-110° C after every 10° C and the temperature coefficient of the reaction speed are calculated on the basis of this equation.

According to the data obtained the temperature coefficient of the reaction in increasing temperature to 10° C in the interval 40-110 ° C, increases 1.46-1.71 times. The found apparent energy of activation the process of conversion of sodium chloride with ammonium sulfate in the indicated temperature interval is 45.23 kJ / mole.

From the results of the research it follows that for the production of sodium sulfate and ammonium chloride by conversion of sodium chloride with ammonium sulfate, is optimal when the process is carried out at a temperature of 100° C and for a period of at least 150 minutes. Herewith, the practical degree of conversion of the initial components is 99.1%. The process of filtration of pulp, formed as a result of the conversion of sodium chloride with ammonium sulfate, was also studied. The experimental data on the filterability of pulps with precipitations of sodium sulfate and ammonium chloride showed that the filterability of the pulp with the precipitate of ammonium chloride is slightly higher than the pulp with the precipitate of sodium sulfate.

The results of the research made it possible to develop a technological scheme for the production of sodium sulfate and ammonium chloride by conversion of sodium chloride with ammonium sulfate.

The proposed technology is worked out on the created enlarged laboratory installation using ammonium sulfate, obtained from sulfuric acid and ammonia at the Chirchik JSC “Electrkimyosanoat” and sodium chloride mined in the Republic of Karakalpakstan.

Let’s analyze its economic indicators. We know that one of the leading sectors making considerable contribution to the development of economy of the republic and its export potential is chemical industry.

Chemical industry in Uzbekistan comprises of the following branches:

• Mining chemistry (minerals extraction);
• Basic chemistry (chemical salts, acids, mineral fertilizers manufacture);
• Chemistry of organic synthesis (manufacture of semi-finished products);
• Polymer chemistry (manufacture of plastic, rubber and fiber);
• Treatment of polymer materials (tire and polyethylene pellicle production

According to State Joint Stock Company O’zkimyosanoat, In January-September 2012, enterprises of chemical industry of Uzbekistan produced industrial products to the amount of 1965.6 billion soums that exceeds indicators of relevant period of the last year by 4.7%. Also there is rise in production of such products as carboxymethyl cellulose (by 2.1 times.), nitric acid strong (by 2.0 times), salt technical (by 2.0 times), acetaldehyde (162.5%), synthetic detergents (149.4%), ammonium sulfate (117.7%), sodium cyanide (113.8%), hydrochloric acid (112.1%), sulfuric acid (104.4%), synthetic ammonia (106.5%), caustic soda (103.2%) and others.

A complex on production of ammonia and carbamide will be constructed in Navoi region by the end of 2014. IPIC of the UAE will allocate US$1.072 billion to the project, Uzkimyosanoat – US$80 million, FRDU – US$150 million and commercial banks – US438 million. The capacities of the plant will make up 660,000 tones of ammonia and 1 million tonnes of carbamide a year.

Construction of ammonia and urea production complex at Navoiyazot OJSC is one of the future projects of State Joint Stock Company O’zkimyosanoat. Project goal — further development and modernization of mineral fertilizers production capacities due to introduction of up-to-date, energy-efficient technologies instead of physically and morally obsolete production.

Used literatures:

1. Х.Ч. Мирзакулов, Г.Х. Джураева. Производство сульфата натрия. – Ташкент, 2014. – 224 с.
2. Патент РУз № IAP 04470. Способ получения сульфата натрия. С.М. Туробжонов, Х.Ч. Мирзакулов, Д.Д. Асомов, Г.Х. Жураева, С.В. Бардин и др. Опубл. бюл. № 2, 2012.
3. The economic report of Uzkimyosanoat/ www.tradingeconomics.com