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DOI: http://dx.doi.org/10.20534/AJT-17-1.2-111-113
Sharipov Khasan T., Tashkent State Technical University, Professor, Doctor of Chemical Sciences, Deputy Chairman of the SUE "Fan va tarakkiet"
Sharafutdinov Ulugbek Z., Navoi Mining and Metallurgical Combinate, Chief of the technical control service of the MA. of the NMMC
E-mail: [email protected]
Rajabboev Ibodillo M., Navoi state mining Institute, researcher
Khujaev Jasur E., Navoi state mining Institute, researcher
Analysis of productive solutions and uranium sorption on anionits
Abstract: Currently of the uranium mined in Navoi Mining and Metallurgical Combinate is obtained by means of underground leaching in the Kyzyl-Kum open pits. This method allows to reduce the cost of uranium mining and ensure the environmentally clean production.
Keywords: uranium, underground leaching, sorption, extraction, rhenium, environmental protection.
Currently, mineral raw resources compound eco- of raw resources' basis consists of hydrogen mines
nomic roots of many developed countries therefore which are based on processing by boreholes of under-
advances of industry and agriculture depends on ratio- ground leaching.
nal and fruitful usage of them by means of creation of Uranium has had a severe impact on many aspects
new technologies which provide complex processing. of intergovernmental relations which are far from sci-
Especially it is about extraction of rare metals which ence, particularly on international politics. Develop-
composes interrelated and sophisticated cyclical pro- ment of mining the uranium in Kyzyl-Kum region on
cess and obtaining final ready products in their pure the basis of physicochemical technology inseparably
forms. Nowadays in uranium industry the main part tied together with common tendency of the global
Section 7. Technical sciences
mining industry and takes place on the background of continuous changes of economic conditions and the demand for raw resources. A significant impact on our economy, along with the production of other rare metals has been made by mining, processing and further use of the uranium. Meanwhile, uranium production technology has many unresolved problems. One of such problems is the quality of incoming salts of sulfuric acid from In Situ Leaching (ISL) departments of Navoi Mining and Metallurgical Combinate.
As already mentioned existing technology involves extracting uranium by the method of in situ leaching and further separation from productive solutions and accumulation on ion-exchange resins. Its use provides selective separation of uranium from solution and its concentration.
While leaching the uranium with sulfuric acid, many other admixture components of rocks are also partly dissolute. Because of this many impurities enter productive solutions with uranium (table 1).
Table 1. - Efficiency of main components of ore in sulfuric acid dissolution
Reaction Extraction in solution, % Concentration of the component in solution, g/l
H2SO4
SiO2 1 0.1-0.5 (SiO2)
CaSi°3 + H2S°4*CaS°4 + H2Si°3
Al2O3 + 3H2SO4* A12 (SO4)3 + 3H2O 3-5 1-12 (A2O3)
Fe,°, + * Fe, (SO4)3 + 3H2O 5-8 3-7 (Fe,O3)
FeO + H2SO4 * FeSO4 + 3H,O 40-50 0.5-3.0 (FeO)
FeCO3 + H2SO4 * FeSO4 + H,O + CO, 80-90 0.2-0.7 (FeO)
CaCO3 + H2SO4*CaSO4 + H,O + CO, 80-90 1.5-2.0 (CaO)
MgCO3 + H, SO4 *Mg SO4 + H2O + CO, 88-90 0.5-3.0 (MgO)
Mo°3 + H2O* H2MoO4 60-90 0.05-1.0 (Mo)
K2O*V2O3*UO3 *nH2O + h2so4* * (VO,)3S°4 + K2SO4 + (n+3)H,O + UO2SO4 92-95 0.5-5.0 (V2O5)
CuO + H2SO4 * CuSO4 + H2O 30-70 0.1-1.0 (Cu)
Ca3 (PO4) 3 + 3H,S°4 * 3 CaS04 + 2 H3 PO4 70-90 0.2-1.4 (P305)
Ca2F (PO4)3 + 5H2SO4 * 5CaS°4 + 3H3P°4 + HF - -
Thus the basic properties of solutions are not changed and are recycled. In the technology of leaching subsequent treatment of solutions are also taken into account. In sorptional extraction of uranium from solutions anionits are mainly used. Accompanying impurities in productive solutions behave inadequately. Cations of alkali and alkaline earth elements, ions of copper, iron, cobalt, manganese, practically are not sorbed. Sulfate, nitrate, chloride, fluoride and phosphate ions are well sorbed and are depressors at this point. In addition, there are anions that can be accumulated in resin and spoil its capacity. In this regard, in the productive solutions concentration of nitrate ions is allowed to appear no more than 0.1 mg/l, chloride and phosphate ions- no more than 0.2 and 0.4 mg/l subsequently. In sulfuric leaching sulfate-ions are accumulated up to 50-100 g/l, which strongly depress ion exchange sorption of uranium.
To prevent accumulation of salts in solutions more than permissible rates and normal performance of ion-exchange extraction of uranium from productive
solutions, partial withdrawal of them from main components to washing with subsequent use of them in technology of leaching. The easiest way of washing sulfuric solutions is lime treatment, in which occurs decreasing of sulfate-ion concentrations up to 5-8 g/l, ions of iron are almost completely precipitated. After the separation of sediment washed out solution is again used for preparation of working solutions.
During in situ leaching process close cooperation between minefield, receiving productive solutions and hy-drometallurgical factory is set. If their distance is longer from each other in accordance with right technological and economical imagination, solutions are processed in minefields until having a concentrate or eluate, when the distance is short, saturated with uranium sorbent or productive solution is sent to the factory. The factory, by turn, accordingly is a provider of either containers or sorbent. The last may be profitable only in cases if the mining complex is situated in the same place with hy-drometallurgical factory.
The process of uranium sorption from productive solutions by strong basis anionits is described by equalization of ion- exchange and complexation:
(r4n+)2so4 + uo22+ + so42-o(r4n+)2 [uo2 (so4)21;
2 (R4N+)2SO4 + UO22+ + 2SO42-o
O (R4N+)4 [UO2 (SO4)2] + SO42-;
2 (R4N+)2SO4 + UO22+ + 3SO42-o
O ^N^ [UO2 (SÛ4)2] + 2SO42-.
Low concentration of uranium in productive solutions (6-10-5 - 4.5-10-4 M) specifies the features of the process of their sorptional processing using anion exchangers. Depending on the pH duration of the sorption of uranyl trisulfate ions with anionits of trimethylam-monium takes from 100 (pH = 1.85) to 500 (pH = 3.6) minutes. In practice, the duration of ionits' contact with recyclable solutions lasts 6-8 hours.
Indicators of uranium sorption process — depth of extraction, capacity of the anion exchanger — depends upon its content in the processing solution, characteristics of anionits and number of ions in the solution-depressants of sorption such as sulfate, nitrate and chloride ions and ions
of iron and sulfuric acid. In the low area of uranium concentration (1-2.5 mg/dm 3) coefficients of its duration is much higher than in high areas (0.1-1.0 g/dm 3) (table 2).
Table 2. - Coefficient of uranium distribution during its sorption with anion exchangers from sulfuric productive solutions with pH = 1.8
Anion exchanger Concentration of uranium in solutions, mg/m3
1 10 25 100 1000
BD-706 9.110 2 6.6-10 2 1.3-10 3 5-10 2 6.9-10 1
Acidity growth in productive solutions brings to the worsening of uranium sorption (table 3).
Anion exchangers have clearly expressed abrupt isotherm of sorption (Kexch), which provides deep extraction of uranium even from solutions with low concentration. As a rule, in the sorption process very low waste concentration of uranium is achieved and it does not exceed 1-2 mg/dm 3. Uranium dumping concentration in processed productive solutions (bittern) determined by residual capacity of ion exchange resins of uranium, pro-
duced in the desorption process. Table 3. - Dependence of uranium distribution coefficient upon the acidity of solution during its sorption with anion exchangers from sulfuric productive solutions
Anion exchangers Acidity of solution
рН = 1.8 5 g/dm 3H2SO4 10 g/dm3H2SO4 20g/dm 3H2SO4
BD-706 Concentration of uranium in the solution 50 mg/dm 3
3.4-10 2 3.1-10 2 2.3-10 2 1.6-10 2
BD-706 Concentration of uranium in the solution 5 mg/dm 3
5.5-10 2 5.1-10 2 4.6-10 2 2.6-10 2
