Method for the selective extraction of uranium from ores

 

(57) Abstract:

The invention relates to the hydrometallurgical processing of orangutango raw materials, in particular to a method for the selective extraction of uranium from ores by leaching and sorption. The inventive ore is subjected to crushing, wet grinding with obtaining pulp and is carried out at a pH of 4.2-2.2 in the one or more devices leaching and forth without performing neutralization at pH 4.6-2.0 leaching process combined with countercurrent sorption of uranium, maintaining the pH in the head in the course of the slurry apparatus ionite processing pH 4.6 to 2.6, preferably 4.0 to 3.6 and at a pH in the tail apparatus ionite processing of 3.4 to 2.0, preferably of 3.2 and 2.4. The temperature of the acid and ionite processing pulp support 30-70oC, preferably 40-60oC. as an oxidant use of manganese compounds, desorption of uranium from a busy ion exchanger exercise sulfuric-nitric acid solutions. 3 C. p. F.-ly, 1 Il., 5 table.

The invention relates to the hydrometallurgical processing of uraniastrasse raw materials and can be used in acid campaign showdown ores for extraction of uranium by ion exchangers.

A method of refining uranopilite the NCA, neutralization with limestone slurry with subsequent separate sorption and desorption of uranium and molybdenum (Technical progress in the nuclear industry. ser. New industrial technology, vol. 5, S. 25, 1994).

The disadvantages of this method are considerable consumption of sulfuric acid 120-140 kg/so

High and also the neutralizing agent (20-25 kg/t CaO) used to adjust (raise) the pH before the sorption of uranium.

There is also known a method of extracting uranium from ore comprising grinding and wet grinding of raw materials, acid leaching in the presence of MnO2or NaClO3neutralizing the pulp NH4OH to a pH of 1.8, the sorption and desorption of uranium (Staroverov D. I. and other Hydrometallurgical processing orangutango raw materials. M Atomizdat, 1979, S. 111-112).

The disadvantages of this method relates primarily to the low selectivity of sorption of the significant content of the ion exchanger impurities at low saturation resins useful component and, as a consequence, high concentrations of uranium in the drawdown pulp.

Currently in the acid processing methods involved silicate ore with higher compared to previously mined raw material concentrations inevitably leads to an increase in consumption of sulfuric acid in their leaching. A significant part of the H2SO4spent on the opening of the iron-bearing minerals, the intensity and completeness of the flow of this process depends on many factors, the main of which is the pH of the processing of the pulp. In certain conditions it is possible to provide a minimal degree of translation in the solution of iron and, consequently, reduce the consumption of sulphuric acid.

Under other equal conditions for the saturation of the ion exchanger uranium is influenced by the pH of the process of ion exchange and the impurity concentration in the liquid phase of the pulp (Fe3+SO24-and others).

In the known method leaching of uranium is carried out at low pH (0,8-1,5), this inevitably translates into solution a large amount of iron, there is an increased consumption of acid, high concentration of sulfate ions. Subsequent neutralization of the alkaline suspension of an alkaline agent to adjust the pH before sorption does not significantly reduce the content in the solution of sulfate ions. An increase in pH to 2.0-2.5 and above leads to the precipitation of iron from the liquid phase into the solid and the coprecipitation of uranium, and with increasing pH, the intensity of these processes is greatly increased.

Thus, in the considered technology in the high pH an increase in its losses. In the first case, there is also a high concentration on the sorbent iron, follow-up which requires additional material costs.

The technical result of the invention is to increase the selectivity of the process of acid-ionite extraction of uranium, i.e., to ensure complete saturation of the sorbent uranium and the minimum concentration therein of impurities, reduction of the consumption of sulfuric acid and in General, reducing the unit cost of extracting uranium from ore processing.

This technical result is achieved that the opening of the useful component and removing the ion exchanger moved countercurrent to the pulp, leading to the conditions under which the iron-containing species is translated into a solution to a minor extent, and uranium in sufficient detail goes into the liquid phase and focuses on the sorbent. In the proposed method, the acid leaching of the ore pulp is carried out in the presence of an oxidant at a pH of 4.2 to 2.2, and countercurrent sorption of uranium at pH 4.6 to 2.0, the output is saturated resin from the pulp is carried out at pH 4.6 to 2.6, preferably of 4.0 and 3.6, the desorption of uranium from a busy ion exchanger (regeneration of the sorbent) are sernistokislogo solutions, the input (supply) aregenerative and sorption is carried out in apparatus of ionite processing. Ion-exchange extraction of uranium on the resin reduces the concentration of the useful component in the liquid phase and leads to additional translation useful component from the ore into solution. The operation of the leaching of raw materials should be carried out in two or three devices with the introduction of acid and steam, which allows to eliminate or significantly reduce their contact with the sorbent.

Acid treatment is carried out at a pH of 2.2 to 4.2, so that in the first during the slurry apparatus ionite processing to maintain an optimal set parameters (pH of 2.6 to 4.6). The most preferred option proposed technology is conducting sorption at high pH in the head, in the course of the slurry, the apparatus to achieve the maximum saturation of the sorbent uranium and the subsequent decrease in pH to the tail unit, which allows for sufficient completeness opening of the useful component and eliminates the possibility of deposition of leached elements and coprecipitation with them uranium.

Regulation of pH sorption in predetermined optimal range may be provided as the supply of reagents and commissioning pulp regenerated acidic ion exchanger, which is determined by the intensity of treatment of the resin in the system of sorption-desorption.

The following are examples of conduct processes for recovering uranium from ores on the proposed technology in comparison with the known method.

For laboratory experiments was composed of the ore charge, in which silicate containing uranium breeds were represented trachydacite, felsite, conglomerate, andesite-basalts and granites; minerals of uranium pitchblende, coffinite, brannerite, uranium black, uranophane, urination and autunite, iron minerals magnetite, hematite, goethite and, to a minor extent, by jarosite and pyrite; carbonates consisted chiefly of calcite and magnesite, dolomite, siderite and ankerite. The content in the charge was, uranium 0,220; SiO266,7; Al2O314,1; Fetotal4,0; CO23-2.1, P2O50,3; Stotal0,2, etc.

In the experiments used the crushed ore, particle size, solid 0,1 mm Oxidizer were dosed out in the original ore slurry, the density of which was 1.3 kg/m3. The process of extraction of uranium led PR is the major anion exchange resin brand AM-n-flow eightfold scheme, the residence time of the pulp and resin on each stage was one hour, the content of the sorbent supported 15% of the volume of the suspension. Desorption of uranium from a busy ion exchanger (regeneration of the resin) was carried out with a solution of H2SO4150-200 g/l and NO310-15 g/l, the output of the eluates was 2.0-2.5 volume on the volume of resin.

In table. 1 shows the performance of hydrometallurgical processing of raw materials by known techniques. The ore slurry containing an oxidizing agent was videlacele for three hours at a pH of 1.2, then neutralized by ammonia water and the above scheme was simulated countercurrent process of sorption of uranium.

Presented in table. 1 data shows that with increasing pH neutralization of from 1.8 to 4.6 extraction of uranium decreases with 94,1 to 76.8% of which is associated with the deposition of leached uranium in the solid phase of the pulp. When the most high extraction component 94,1% (experiment 1) observed the lowest saturation of the ion exchanger uranium 8.6%, and a significant concentration of its impurities (Fe 1.1 percent).

Similar results were obtained when using as a neutralizing agent CaO.

The process indicators that were proposed technology is shown in table. 2.

Vyselki the wound with input regenerated acidic ion exchanger, output saturated resin was carried out at pH 4.6 to 2.0; desorption of uranium from a busy ion exchanger (regeneration of the sorbent) spent sulfuric-nitric acid solutions followed by submission of regenerated resin on the sorption of uranium. The residence time of the pulp and resin on stage, the parameters of desorption supported similarly to the simulation processing of the ore slurry by a known method.

The obtained data (table. 2) show that in all cases, equal in comparison with the known method the extraction of uranium 94,1% of the proposed technology achieved a higher degree of concentration of the useful component of the sorbent 11,2-12,6% against 8.6-11.2% in the conventional method (table. 1), the iron content did not exceed 0.2% vs. 1.1% at the same time the technology has reduced the consumption of sulfuric acid from 110 kg/t up to 74 kg/so

Justification the boundary of the parameter values of the proposed method for the selective extraction of uranium shown in the drawing and table. 3, 4 and 5. The graph shows the dependence of the content of iron in the solid phase from pH treatment of the pulp. The obtained curve shows that in the region of pH 4.6-2.6 degree of transfer of iron in the solution is minimal, while lowering the pH of acid DoD it in the liquid phase of the slurry, that, in turn, causes a significant increase in the consumption of solvent is sulfuric acid, increasing the concentration in solution of sulfate ions and iron and, thus, reduce the completeness of the saturation of the sorbent uranium.

Accordingly, the graphical dependence shows that the minimum boundary value of the pH of the raw materials is of 2.0, which is confirmed by the indicators table. 3, obtained by simulation of the circuit eight-speed countercurrent acid-ionite processing of the pulp.

The presented data (table. 3) show that when pH decreases from 2.0 to 1.6 and then to 1.0 acid consumption increases accordingly with 74 kg/t to 98 kg/t and 125 kg/t, the cost increase from 7.2 $ /t to respectively 8,2 $ /t and 8.8 $ /so

Area pH input of the reactivated sorbent (final stage ionite processing of raw materials) is 2,0-3,4, with costs not exceeding 7,3 $ /t, the preferred area boundary values of pH with minimal cost to 7.0-7.1 $ /t defined 3,2-2,4.

From the data table. 4 area boundary values pH o saturated resin is determined in the pH range of 4.6-2.6 iron content in the sorbent does not exceed 0.2% and its saturation with uranium compiled by the increased concentration of uranium on the sorbent to 10.5-9.9% and in the latter case, the increase of iron content on the ion exchanger. The maximum saturation of the sorbent is observed at pH values of 3.6 to 4.0.

Similar patterns were obtained using for acid-ionite processing of the raw material resins EAP-AP and AMP.

Thus, it is shown that the area in which the process of sorption of uranium, combined with the additional extraction of it from the solid phase of the ore pulp is in the range of pH values of 4.6-2,0; its lower boundary is determined by the minimum value of pH (2,0), when the reduction begins intensive transition of iron in solution, respectively, increasing the flow rate of the solvent and increasing the concentration of sulfate ions in the solution; the upper boundary is determined by the optimal saturation of the sorbent with the lowest amount of iron on it, above pH 4.6 concentration of uranium on the resin is significantly reduced.

For the leaching of uranium without the presence of the resin region pH of the processing of the pulp is determined within the range of 4.2 to 2.2; the upper boundary value provides an extremely high pH of the sorption process 4,6, minimum value pH leaching is included in the above optimal region of the opening of iron-containing minerals (pH of 2.0).

The limits of the pH of the pulp at the conclusion of the saturated sorbent and the input handle is 4,6-2,6 and 3,4-2.0 and preferred values respectively 4.0 and 3.6 and 3.2 to 2.4.

In table. 5 presents the performance management process on the proposed technology in the field of optimal pH values (leaching 3.6V; output saturated sorbent 4,0; enter regenerated ion exchanger 2,8) at different temperatures of the processing of the pulp.

Unit costs on the selective extraction of uranium from ore slurries, given its technological losses, amounted to $ 7.1 $ /t at a temperature of 40-60oC and 7.2 $ /t at a temperature of 30-70oC. Raising the temperature to 80oC, as well as its reduction to the 20oC, leads to increased costs to 7.4 $ /tons At identical temperatures processing unit costs by a known method was 9.6-9.9 $ /so

In General, the presented data show that the proposed method is compared with the known allows to reduce costs for hydrometallurgical processing uraniastrasse raw materials and to increase the selectivity of the extraction of uranium.

1. Method for the selective extraction of uranium from ores comprising grinding and wet grinding with obtaining pulp, acid leaching with the introduction of the oxidant, countercurrent sorption of uranium from the pulp when combined with leaching with the introduction of the resin, the saturated output of the ion exchanger, is that acid leaching is carried out at a pH of 4.2 to 2.2.

2. The method according to p. 1, characterized in that when the output of the saturated ion exchanger support pH 4.6 to 2.6, preferably 4,0 3,5, and when entering the regenerated ion exchanger 3,4 2,0, preferably 2,4 3,2.

3. The method according to p. 1, characterized in that the temperature acid leaching and sorption of pulp support 30 70oWith, preferably 40 to 60oC.

4. The method according to p. 1, characterized in that the desorption of uranium from a busy ion exchanger exercise sulfuric-nitric acid solutions.

 

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