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Section 9. Technical sciences
DOI: http://dx.doi.org/10.20534/ESR-17-3.4-90-92
Alikulov Shukrat Sharofovich, Navoi State Mining Institute.
Senior Research Fellow, candidate of technical sciences.
Uzbekistan, Navoi E-mail: [email protected]
Methods of technological processes' intensification of in situ leaching of uranium from low-penetrating ores
Abstract: However, it is studied with electrical exposure to the leaching layer or passing to it working solutions in this work. Alternating and direct current are used. During electrical impact on to be leached ores various physic-chemical processes are followed: electrolysis, gas evolution, heat generation, electroosmosis, electrophoresis, strengthening, fastening, thixotropy, softening, dipolephores and so on. Depending on the mode of influence prevails one or another process. Impact with high frequency is used for worming up the massif which has low-penetrability and low-electro conductivity (oil, sulphur deposits). Thermal energy is generated thank to dielectric lose. The impact promotes lowering of oil viscosity, paraffin melting, well mud-ding, sulphur melting. Impact with direct current. First experiences of electrical impact were held by the institute of. The main effects are electrophoresis, ore-solution system's electrolysis, dissolution of chemical mud fillers. Disadvantages of this method are high speed corrosion of anodes and gaseous mudding of filtering zones. Externally, under direct electrostatic field ions of metal and leaching solution acquire ordered motion.
Keywords: uranium leaching, exposure to alternating electric current, electric action, filtration, filtration coefficient, diffusion rate, uranium content, preparation of ore deposits, productive solution, working solution.
Conception of "intensification methods" is practically respectful with the usage of various physical, hydrodynamical, chemical and other methods that accelerate mass exchange processes while solutions pass through orebody.
Nowadays, in in situ leaching method of uranium mining, preparation of ore deposits is occurred in three directions: physical method (hydraulic rupture of the layer), chemical method (chemical interaction ofleaching reagents with well-soluble uranium minerals) bacterial exposure on to be leached ores.
However, it is studied with electrical exposure to the leaching layer or passing to it working solutions in this work. Alternating and direct current are used.
During electrical impact on to be leached ores various physic-chemical processes are followed: electrolysis, gas evolution, heat generation, electroosmosis, electrophoresis, strengthening, fastening, thixotropy, softening, dipolephores and so on. Depending on the mode of influence prevails one or another process.
Impact with high frequency is used for worming up the massif which has low-penetrability and low-electro conductivity (oil, sulphur deposits). Thermal energy is generated thank to dielectric lose. The impact promotes lowering of oil viscosity, paraffin melting, well mudding, sulphur melting.
Impact with direct current. First experiences of electrical impact were held by the institute of. The main effects are electrophoresis, ore-solution system's electrolysis, dissolution of chemical mud fillers. Disadvantages ofthis method are high speed corrosion ofanodes and gaseous mudding of filtering zones. Externally, under direct electrostatic field ions of metal and leaching solution acquire ordered motion.
The impact with alternating current is directed on desorption of friable connected water with surface of capillaries and on hardening
clayiness of admixture sandy-argillaceous ores with a purpose of prevention of its swelling and postponement in the form of mudding sediments; listed effects from electrical impact promote growth of ore's penetrability in filtering zones and rise of ell's average productivity to 25-30%.
An impact with high density current. At the expanse of intensive energy generation in narrow areas of capillaries their augmentation and cleaning-up take place as a result of which during short period irreversible effect of penetrability increase is created. Unlike listed above methods which rely on development in the sphere of electroosmosis, in this method energetic approach is used, theory of percolation and development in an area of rigid body physics.
On uranium administrations complex approach of electrical impact on strata that takes into account all main physical effects which promotes imposition of electricity current on ore.
It is evident from provided brief characteristics of methods that all of them figured on growth of penetrability of orebody. Sufficient reasons of theory electrical impact on speed of chemical reactions of leaching does not exist yet. If we stipulate intensification of leaching in the system of ore-solution in accordance with electro dialysis rules, then taking into account mineralization of solutions we will find that allocation of 1 kg metal on cathode in productive well requires a few thousands of kilowatt-hour electricity. Though, in experiments of and our studies it is followed that some increase of concentration of metals in solutions under electrical impact (about 20%) that points at necessity of accounting all diversity of factors while developing theory of chemical reactions' intensification of leaching metals with electrical power:
- reanimation of leaching solutions filtration in ore layers thank to selective growth of their penetrability;
Methods of technological processes' intensification of in situ leaching of uranium from low-penetrating ores
- disclosure of capillaries that were unavailable for leaching solutions before;
- desorption of metals with electrical power from walls of capillaries along with friable connected water;
- prevention of postponement of metals on the front of leaching;
- improvement of structure of leaching solutions' stream in regions of production and injection lines (from radial to plane-parallel) thank to creation of zones with advanced penetrability between wells and lines. Other processes are also possible.
Positive results of laboratory experiments that show possibility of connected water cast and particles of clay binder which are components of hydrogen deposits, to bring into movement under impact on them with alternating current of low voltage, full-size experiments on sole wells, allowed to pass to industrial sampling and application of the method.
To establish an impact of alternating current exposure on solutions' movement in sandy-argillaceous ores preliminary connected (friable connected and adsorbed) waters and alteration of filtration coefficient in process of filtration 1% solution of sulfuric acid. Filtration studies were held on ore sands with mixture of clay (1,5 and 10%) montmorillonite and hydromica content.
Two similar trials were executed: first one was held on distilled water, another one was held on productive solutions from industrial field of ISL. Change of clay sand's humidity over length of columns. According to methodology, three zones were separated out from top to bottom: capillary humidity, maximal molecular humidity. Maximal molecular humidity in experiment with productive solutions 12% witnesses that some swelling of clay fractions of ores in solutions.
Results of experiments showed us that during filtration of leaching solutions by ores of specific mining field friable connected
water which accounts for certain poral volume, creates hydraulic resistance. Share of connected water in the volume of 1sm 3 of soil with a humidity of 10% constitutes for: wyn 10% -1,7
V = -
- = 0,17 cm 3
100%ya 100% -1,0 Where w - 10%-maximal molecular humidity, yn = 1,7 g/sm 3 -relative density of dry sand: ye = 1,0 g/sm 3 - relative density ofwater.
Taking into consideration that 40% of porosity in 1sm 3 orebody occupies 0,4 sm 3 volume, it is evident that huge role of connected water in filtration process (in this case it occupies 42,5% volume of pores):
100% •017 = 42,5 % 0,40
In the process of filtration, we measured the discharge of solutions and its temperature. On the basis of measurements, we have calculated the coefficient of penetrability of ores with a formula Kn = Ql»/(F AP), Where Q - solution's discharge, sm 3 / s; l - length of the sample, sm; ^ - viscosity, sP; F - net area of the sample, sm 2; AP - differential pressure, kg/sm 2.
Of the results of the experiments it can be concluded that rise of clay concentration considerably brings dawn penetrability of ores. Penetrability of ores that measured by acid solution, turns to be significantly lower than penetrability of distilled water. Notably, appearance of gaseous mudding was not determined in experiments.
Filtration experiments were held in two tubes simultaneously: in one - with application of electrical power, in another- without electrical power. The impact with alternating current on orebody was occurred periodically. Alteration of filtration coefficient and metal concentration in solution in dependence from correlation of S: L is demonstrated in figure 2.
Figure 1. Dependence of filtration coefficient K concentration of metal in solution from S: L during periodical impact with
electrical power and without electrical power
As can be seen from the graph, during the impact with electrical power not only coefficient of filtration rises, speed of metal extraction is also increases. Improvement of filtration coefficient is interpreted by us as a result of solution's viscosity reduction in consequence of its worming up while impacting with electrical power and as a result of connected water's transmission into moving condition that brings an improvement of effective cross-section of pores and penetrability of ore.
From considered electro physical methods up to industrial application in in situ leaching of ores from hydrogen deposits it is carried out wells' processing by electro hydraulic impact that increases
penetrability of sand-clay layers direct or alternate currents of industrial part.
Filter processing and filtration zones with electrohydraulic hit in the administrations of ISL methods of regeneration of filters and filtration zones (high-pressure retreatment with water, pumping with compressed air, chemical mud fil cleanning) is characterized short time requirement and negligible increase of well productivity. More prospective is a method of electrohydraulic hit in combination with compressed air pump to the well. The research is accomplished by the electrohydraulic hit equipment with following technical characteristics:
50m --
i-^-----
Figure 2. the scheme of cell with impact on layer with alternate current
Table 1.
Maximal depth of treatment, m 150
Tension, kV 50
Volume of impulsive condensator, mkF 0,5
The charge tension, V 220
Consuming power, kVt 1
An essence of the physical effect of sandy-argillaceous ores' promotion while transmission ofelectrical power in department ofloamy fractions associated water, whereupon increases section of pores. Besides, unlike constant current, alternating current impacts on water too that immobilized by helium, mudding pores spaces. Thixotropic (helium like) structure is formed in contact with sulfuric acid and argillaceous fraction of the ore owing to crystallizational cement's solution and their softening. Helium even during negligible quantity of solid material (1-10%) accounts a big volume, that stipulated net structure in cells ofwhich contains 90% and higher immobilized water. Immobilized water differs from water ofdiffusive layer with the first is not connected with cations and not pulled up surface charges of particles.
DOI: http://dx.doi.org/10.20534/ESR-17-3.4-92-94
Atabaev Farrukh Bakhtiyarovich, doctor of philosophy (Ph. D.) in technics, senior scientific research, research and test center «Strom» Institute of General and inorganic chemistry of Academy of Sciences of the Republic of Uzbekistan
E-mail: [email protected].
Waste from flotation enrichment of rocks — as a complex raw material for the cement industry
Abstract: Provides information about the possibility of obtaining an extension of the portlandcement with the use as additives-fillers secondary raw materials: recycled steel slags, waste, flotation of tungsten, and fluorite ores of Uzbekistan, "dry" and "wet" wastes of production of chrysotile-cement products.
Keywords: beneficiation of ores by flotation, secondary raw materials, additive in cement, portland cement additional, physical and chemical properties, structure, hardening, the formation of artificial conglomerate, strength, brand, environment, economy.
Introduction. The trend of development of the cement industry of Uzbekistan is aimed at reducing fuel and energy costs per unit of production and increasing the volume of cement production through maximum involvement in the production process local raw materials of natural and anthropogenic origin, not worsening the quality of cement. To do this, cement plants of the republic carried out a deliberate policy on the adoption of appropriate measures in the field of exploration of promising new sources of local cement raw materials. In this aspect, the most important is the question of finding new sources of mineral admixtures and additives — filling cement, clinker ensure maximum savings component while improving the physical and mechanical, construction and technical properties of the cement additive.
Formulation of the problem. Due to the fact that the flotation tailings tungsten (FTTO) and fluorite ores (FTFO) are alumino-silicate minerals with impurities of different oxides may be used as additives to cement. This requires a comprehensive study their properties in order to determine the possibility of using as an additive in the production of cements with additional optimization of their content in the composition of additional cement and to determine the physical and mechanical properties and compliance with the data requirements of the Interstate standard GOST 10178-85. At the same time, the development and application of technology for additional cement using waste flotation concentrators is not only technically feasible option saving energy and resources in the production of ce-
ment additive, in quality not inferior without additional cement and physico-mechanical properties meet the requirements for cement with mineral additives brand PC 400 D20, but the actual decision of environmental problems.
Materials research methods, equipment and instruments. During the experimental research as the starting materials used are Portland cement clinker ofJSC "Kizilkumcement" and JSC "Akhan-garancement", gypsum, flotation tailings deposit Ingichka tungsten ores and fluorite ores (deposit Agatha — Chibirgata). Investigations were carried out in an accredited laboratory of the Research and Testing Centre "Strom" Institute of General and Inorganic Chemistry of the Academy of Sciences of Uzbekistan, which is equipped with the necessary tools and equipment to perform chemical analysis and physico-chemical and physical-mechanical source of raw materials and cement (analytical laboratory, DTA, IR, X-ray, electron microscope). Determination tails activity enrichment fluorite and tungsten ores in order to establish their application as active mineral or filler additive for Portland cement, carried out by determining their compressive strength and, then by calculation — by Student's test according to the procedure of GOST (State Standard) 25094.
Results and its discussion. Determination of the chemical composition of samples of the flotation tailings fluorite ores showed that its chemical composition is represented mainly by the content of silicon oxide, the presence of calcium oxide, aluminum,
