The method of extraction of uranium from ores

 

(57) Abstract:

The invention relates to the extraction of uranium from ores by means of heap or underground leaching. The method includes filtering through the ore leach solutions containing sulfuric acid and nitrate ions with the translation of hexavalent uranium, ferrous iron in the final solutions, the extraction of uranium with obtaining uterine fluids. In the preparation of leach solutions of sulphuric and nitric acid is introduced into the part of the mother solutions, 0.05 to 0.15 from their original volume, taken from the conditions of maintenance of redox potential 750-850 mV, then the resulting solution in contact with the other part of the mother solutions with providing redox potential 600-700 mV. The resulting solution is mixed with the remaining volume with providing redox potential 420-500 mV. This oxidized solution serves on the leaching of uranium from the ore. The method allows to intensify the process. 4 Il., 3 table.

The invention relates to the hydrometallurgical processing of ores and can be used in particular in uranium hydrometallurgy leaching it from ores methods and PV using sulfuric acid, the essence of which is to infiltration of dilute its solutions through a layer of ore stacked in a heap, either directly through the ore-bearing formation; nitric acid is introduced into the solution for passivation equipment. The disadvantage of this method of leaching chosen as a prototype, is the low intensity of the process, most of its length /L. I. Lunev. Mine development system deposits of uranium underground leaching. M., 1982, page 8,13,17/.

It is also known that salts of trivalent iron contribute to the intensification of the processes of leaching due to oxidation of U (IV) in the more soluble U (VI) /There/. As such a catalyst can be used ions of iron (II) contained in the circulating leachate solutions when they are oxidized to the trivalent state by any oxidants. In practice, however, such a process does not exist in the absence of an effective oxidant. From a number of tested us oxidants were most active nitrous acid, the distinguishing feature of which is its ability to vigorously react with Fe (II) in acid solutions at ordinary temperature, in Florida air, may involve the latter in the oxidation process for the catalytic scheme. However, compounds containing nitrous acid, are produced on a limited scale (nitrite), or as a commercial product not available (nitrogylcerin acid). In addition, the compounds of nitrous acid at a sufficiently high price.

In light of the above important question is how the oxidation of Fe (II) in the circulating solution with nitric acid as a starting reagent to generate from it nitrous acid.

The technical result is the intensification of the process. It is achieved by way of extraction of uranium from ores by means of heap or underground leaching, comprising preparing leach solutions containing sulfuric acid and nitrate ions, filtering them through the ore with the translation of hexavalent uranium, ferrous iron and other metals in production solutions, the extraction of uranium with obtaining uterine fluids and recycling of these solutions on the leaching of ore, according to the invention, in the preparation of leach solutions of sulphuric and nitric acid is introduced into the part of the mother solutions, 0.05 to 0.15 from their source on the recreational potential of 750-850 mV, then the resulting solution and the resulting nitrogen oxides in contact with another part of the uterine fluids equal to 0.25-0.35 of its original volume and is taken from the conditions for oxidation of Fe (II) Fe (III) with achievement of the redox potential 600-700 mV when the dispersion in a solution of oxygen or air, then mixed with the remaining volume with providing auxiliare-reduction potential of the solution is equal to 420-500 mV, and before the introduction of sulfuric and nitric acid in the mother solutions produce the absorption of nitrogen oxides formed during the preparation of pls, by their contact with the source of the uterine fluids.

Formed during the interaction of the products of the decomposition of nitric acid ions Fe (II) nitrous gases first contact with a source of circulating a solution of HF or MF for absorption of these solutions with the formation of the complex Fe(NO)SO4and subsequent to their involvement in the oxidative process for admission into the reaction apparatus oxidation.

Thus the intensification of the process of leaching of uranium from ores methods KV or PV is achieved through the use of circulating solutions in which ions Fe (II Fe (II) Fe (III) is carried out mainly by oxygen, Bartiromo through the recirculating solution, when the catalytic participation of nitrous acid and nitrogen oxides resulting from the decomposition of nitric acid, which is the source of nitrogen-containing reagent.

Example 1. The oxidation of Fe (II) nitrous acid in combination with oxygen.

The experiments were carried out in a column, in the lower part of which was soldered filter SCHOTT, providing the dispersion introduced into the solution of air. The content of sulfuric acid in the solution was 10 g/l, the concentration of Fe(II) ranged from 1.0 to 9.0 g/l, room temperature. The air flow rate was 140 l/h, the height of the liquid column 150 see the results of the experiments are given in table. 1.

As seen from the above table. 1 data, due to the high oxidation activity of nitrous acid and the dispersion of air oxidation of iron (II) in a wide range of concentrations takes place at room temperature already at a flow rate of nitrous acid, equal to 8% of the stoichiometric required, provided that the part 2air; when smaller proportion of nitrous acid to iron (II) speed of this process is dramatically reduced.

Example 2. Absorption of nitrogen oxides. The study of p is the height of the absorbing layer. In the lower part of the apparatus filed nitric oxide, produced by the interaction of a 40% aqueous solution of NaNO2with 20% solution of FeSO4in hydrochloric acid, and air. The absorption process was studied at room temperature in solutions containing 5 g/l Fe (II), the concentration of nitric oxide in the gas mixture fed to the apparatus, was 0.3 and 0.5 vol.%. The experiments were conducted in the mode of short-contacting gas with liquid (75 sec).

In Fig. 1 shows the dependence of the degree of absorption of the degree of immersion circulator at /Fe+2/ = 5.0 g/l and flow rate of the gas mixture: 1-2,8; 2-3,2; 3-4,0 l/min /NO/ 0.3 to about.%; 4-2,8; 5-3,2 l/min /NO/ 0,5% vol.

In Fig. 2 given the degree of absorption of nitrogen oxides from the flow of the gas mixture at /Fe+2/ = 5.0 g/l and the degree of immersion circulator: 1-40; 2-50; 3-60% (concentration Akilov nitrogen 0,3 vol.%); 4-30; 5-40% (the concentration of nitrogen oxides is 0.5 vol.%).

As is clear from these experiments, with increasing degree of immersion circulator, gas flow and dispersion of gas bubbles absorption of nitric oxide increases. Therefore, in practice, for a more complete absorption of nitrogen oxides from waste gases should be used in the devices column type, equipped with a dispersing device is R> The complex Fe(NO)SO4in acidic environments, stable only at temperatures below the 25oC. With increasing temperature, its stability decreases dramatically, allowing you to count on the possibility of regeneration of nitrogen oxides. To assess the effectiveness of the regeneration process of their solutions, held a special series of experiments, the results of which are given in table. 2. The destruction of the complex Fe(NO)SO4was carried out by heating the solution to 50oC without stirring and bubbling through the air.

From the above table. 2 data shows that the decomposition of the complex Fe(NO)SO4at a temperature of 50oC and bubbling air flows at high speed and after 10-20 minutes the complex is completely destroyed. This means that in terms of the proposed process captured on site gas purification oxides of nitrogen later in the oxidation reactor will be involved in the process of catalytic oxidation of iron (II).

Example 4. The decomposition of nitric acid and the oxidation of Fe (II).

In chemical glass injected 100 ml of a solution containing 1.0 g/l Fe (II) under stirring there serves the calculated amount of concentrated sulfuric (beats. century 1,83) and attem in this solution is further added a solution of ferrous iron in an amount of from 100 to 900 ml and measure about-VP the resulting solution. The results of these experiments are given in table. 3.

As can be seen from the table. 3, by mixing 100 ml of the original solution of Fe (II) with 15 g of sulfuric acid, the solution temperature due to heat of hydration rises to 40-42oC, B. N. after injection of 0.3-2.0 g of nitric acid is only 415-450 mV. However, with the introduction of 2.25-3.0 g HNO3this figure reaches 800-860 mV.

When applying to the original solution of 30 g of copper sulphate oil temperature of the solution rises to 56oC and o-VP reaches 800-860 mV already when applying 1 g of nitric acid.

When additional supply in the resulting oxidized solution 200-300 ml of the original solution of Fe (II)-VP mixture ranges from 550 to 750 mV, and after another 600 ml is 425-460 mV, which corresponds to the ratio of Fe (III)/Fe (II) in solution is about 1:1 and in terms of PV will provide an oxidizing atmosphere. In combination with bubbling air, as it follows from example 2, the oxidation of iron (II) exceeds 70%.

Example 5. Leaching of uranium ore oxidized solution.

In a column with a diameter of 35 mm, load 300 g sandy ore natural size with a uranium content 0,214%. Ore soaked with water, "zachisliaut"who are you and ions Fe (III), obtained by the oxidation of Fe (II) in example 4.

Daily output from the column selected sample production solution, determine its content of uranium. The leaching is carried out to as long as coming out of the speakers solutions of the uranium content is below 10 mg/l

A similar method of conducting experience with one solution of sulfuric acid without the addition of iron (III).

The results of the experiments shown in Fig. 3.

As follows from the data of Fig. 3, the presence of leaching solutions of ferric (VP solution of 500 mV, curve 2) provides an increase in the degree of extraction of uranium from the ore by the method of the RO at W:T equal to 3-4, 12-15%, or reduction of the duration of the leaching process 3-4 times in comparison with the results of using one solution of sulfuric acid (C. p. 370 mV, curve 1, Fig. 3).

Sum of the above in examples 1-5 data suggest that with the introduction of a limited amount of a solution of Fe (II) calculated quantity of concentrated sulphuric and nitric acids, the conditions for the decomposition of nitric acid retrieved from the nitrous acid, which in combination with the supplied dispersed by air oxidation stereoselective uranium from the ore as a whole.

Based on the available aggregate data serves a schematic diagram of oxidation of circulating solutions of HF and MF using nitric acid as the initial reactant and oxygen in sulfate environment (Fig. 4).

The method of extraction of uranium from ores by means of heap or underground leaching, comprising preparing leach solutions containing sulfuric acid and nitrate ions, filtering them through the ore with the translation of hexavalent uranium, ferrous iron and other metals in production solutions, the extraction of uranium with obtaining uterine fluids and recycling of these solutions on the leaching of ores, characterized in that in the preparation of leach solutions of sulphuric and nitric acid is introduced into the part of the mother solutions, 0.05 to 0.15 from their original volume, taken from the conditions of establishment concentration of sulfuric acid, 100 - 250 g/l and the redox potential of 750 - 850 mV, then the resulting solution and the resulting nitrogen oxides in contact with another part of the uterine fluids equal to 0.25 - 0.35 of its original volume and is taken from the conditions for oxidation of Fe (II) Fe (III) with achievement of the oxidation-reset the military solution with the remaining part of the mother solutions with maintenance of the redox potential of the solution, equals 420 - 500 mV, and before the introduction of sulfuric and nitric acids in the mother solutions produce the absorption of nitrogen oxides formed during the preparation of pls, by their contact with the source of the uterine fluids.

 

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FIELD: nonferrous metallurgy.

SUBSTANCE: invention aims at recovering uncommon metals from silicate ores and concentrates in processing of zirconium concentrates. Method according to invention envisages treating cake obtained by caking zircon concentrate with calcium oxide in presence of nitric or sulfuric acid. Concentrated acid is added to water-slurried cake at constant speed during 30-60 min in two steps so that 18-25% of acid is added during first 30 min, whereupon zirconium is leached at 80-90оС.

EFFECT: increased filtration velocity and simplified process due to reduced number of operations.

2 cl, 2 dwg, 4 ex

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