Recently, more and more attention is paid to the ecological safety of the republic due to the increased threat of environmental pollution by radionuclides, particularly by uranium, while the processing of uranium-containing raw materials generates a significant amount of liquid industrial waste. The main waste disposal method is a sorption, which requires the use of inexpensive sorbents. Such sorbents can be obtained on the basis of domestic natural raw materials. The significant disadvantages of natural sorbents are a low sorption capacity, which can be increased by developing effective and relatively cheap methods for their modification. The absence of the methods of modification is a limiting factor for the widespread using of natural sorbents for environmental purposes. Variants of modification of natural aluminosilicate and coal-mineral raw materials of Kazakhstan by physical and chemical methods are considered. The chemical methods include the modification with a mixture of tributylphostat and di-2-ethylhexylphosphoric acid in kerosene to obtain "solid-phase extractants", a mixture of phosphoric acid and polyacrylamide, and the synthesis of organominerals. The possibility of using technogenic raw materials as a modifying reagent has been studied. Zeolite of the previously unexplored Kosmurun deposit and shungite of the Koksu deposit were selected for research, and slags of phosphorus production were selected as a technogenic raw materials. Their physical and chemical properties have been studied.
Hydrometallurgical processing of uranium-containing raw materials generates a significant amount of liquid industry-related waste, namely waste solutions that require disposal. Sorption is known as one of the most effective methods for purifying liquid matters contaminated with radionuclides. Various modification options are being developed for the purpose of using natural sorbents and increasing their sorption capacity. The authors proposed the methods for modifying natural aluminosilicate and coal-mineral raw materials. Zeolite found at the Kusmurun deposit and shungite from the Koksu deposit were selected for the research. The methods are based on obtaining solid-phase extractants. It was proposed to modify natural sorbents with a mixture of tributyl phosphate and di2-ethylhexyl phosphoric acid in kerosene, as well as a mixture of phosphoric acid and polyacrylamide. It was demonstrated that the first method is preferable for zeolite, and the second one for shungite. The research addressed the sorption properties of modified sorbents in static and dynamic modes. Uranium sorption isotherms were plotted. The maximum sorption capacity and the Langmuir constant were calculated. The research allowed synthesizing an organopolymer based on shungite, glycidyl methacrylate, orthophosphoric, and hydroxyethyl diphosphoric acids. Its sorption properties were studied under dynamic conditions. Its sorption capacity was assessed in comparison with modified natural sorbents.
When obtaining sulfuric acid from pyrite concentrates, a significant amount of waste is generated in the form of pyrite cinders that require disposal. The methods used in processing this raw material are, as a rule, the pyrometallurgical processes of chlorination and chloride sublimation, the disadvantages of which include increased energy consumption and a lack of complexity in the extraction of valuable components. Hydrometallurgical processes are in less demand due to their multi-stage nature and complexity of execution. The method of chemical activation developed at the JSC “Institute of Metallurgy and Ore Beneficiation” makes it possible to isolate iron and non-ferrous metals into separate, middling products and to concentrate noble metals in the cake at the first stage. Physical and chemical studies of the cake found that its basis comprises iron compounds. The silver in the cake is associated with pyrite, while the gold is associated with hematite; it is also possible to find gold in the form of AuCl3. The content of gold in the cake is 1.5 g/t, and the silver content is 17.7 g/t. Based on physical and chemical studies and data from the literature, various versions of the hydrochlorination method are proposed to open the cake.
The presence of uranium-containing wastes from large provinces in the Republic of Kazakhstan significantly complicates the ecological situation, causing damage to the soil and hydrosphere due to the uncontrolled spread of large volumes of natural waters contaminated with radionuclides. They are usually utilized by the sorption method; however, the use of synthesized sorption materials is limited by their high price, and natural minerals are limited by low sorption characteristics. Many modification options are used in order to improve the sorption characteristics, but only a few methods have been found applied in industry. The main disadvantages include the complexity in the application and modification of reagents rarely used in industrial practice, which increases their cost, and is an obstacle to their widespread use. The authors of this research have studied the possibility of using technogenic raw materials—slags of phosphorus production—as a modifier of natural minerals. The methods of slag activation are investigated, the optimal conditions for the modification of the natural minerals zeolite and shungite by activated slag are determined, and the sorption properties of modified sorbents are studied.
With the huge explored reserves of potash salts in Kazakhstan, there is still no production of potash fertilizers, the demand for which is constantly growing. In this regard, research of processing of the largest Chelkar deposit ore into potash fertilizers and salts is an urgent problem. The article presents the research results of washed potash ore decomposition with nitric acid and nitric acid suspension filtration. The filtering properties and granulometric composition of the insoluble residue were studied, on what basis the decomposition mode with precipitate double washing was determined. To ensure good suspension filterability, washed, uncalcined ore should be used. Tests of a by-product, gypsum, as a gypsum binder were carried out, which confirmed its compliance with the normally hardening gypsum binder of the G-2 B grade. Advantage of the obtained gypsum is its environmental friendliness. Salts, which are chlorine-free water-soluble potassium-magnesium fertilizers have been obtained by crystallization from nitric acid solution. On the basis of results of experimental-and-laboratory tests, a basic flow scheme has been developed for obtaining potash and complex potassium-nitrogen-magnesium fertilizers from the Chelkar deposit ore.
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