RU2200204C2 - Method of processing uranium ores - Google Patents

Abstract

FIELD: extraction of ore raw materials. SUBSTANCE: uranium ore is subjected to crushing and wet grinding to obtain pulp which is later subjected to thickening, acid agitation leaching, sorption of uranium from pulp, desorption of uranium from ionite saturated from pulp and desiliconization of ionite. Then, acid percolation leaching of ore is performed which is followed by sorption of uranium from solutions, desorption of uranium from ionite saturated from pulp and solutions, re-extraction of uranium at separation of crystals ammonium uranyl tricarbonate and calcinating resulting in obtaining uranous-uranic oxide; waste ion-exchange material at size of 0.6 to 0.2 mm ≥95%, is subjected to desiliconization and is later used for sorption of uranium from percolation leaching solutions for ion- exchange treatment of circulating and waste water. Proposed method ensures reduction of consumption of ionite and content of admixtures in circulating and waste water. EFFECT: enhanced efficiency; additional yields of certified commercial products. 2 dwg, 3 tbl, 3 ex

Description

 The invention relates to the field of processing of uranium-containing raw materials and can be used in the extraction of metals from ores.

 A known method of processing uranium ores, including crushing and wet grinding to produce pulp, thickening, acid agitation leaching and sorption of uranium from pulps, desorption of uranium from an ion exchanger saturated from pulp, desilination of the ion exchanger as silicon accumulates on it, extraction of uranium from desorption eluates, reextraction with the release of crystals of ammonium uranyl tricarbonate and calcination to obtain uranium oxide (Sheludchenko V.G., Spirin E.K., Litvinenko V.G. Technologies for propaganda leaching of uranium from ores // Mountain weight nick - 1998 - 3 - S.25-28). The disadvantages of this method include the high cost of the final product.

 A known method of processing uranium ores, including acid percolation leaching and sorption of uranium from solutions, desorption of uranium from saturated ionite and precipitation of a chemical concentrate from desorption eluates (Gromov B.V. Introduction to the chemical technology of uranium. - M .: Atomizdat, 1978, - С .72-73, C.108-112). Compared with the previously considered method, this technology does not use the operations of grinding and agitation of ore material, which significantly reduces the cost of the extracted metal. The disadvantages of the percolation method include the long processing time of the raw materials and lower extraction of uranium.

 The closest adopted for the prototype is a method of processing uranium ores, including crushing and wet grinding to obtain pulp, thickening, acid agitation leaching and sorption of uranium from pulps, desorption of uranium from an ion exchanger, saturated from pulp, desalination of an ion exchanger, and acid percolation leaching , sorption of uranium from solutions, desorption of uranium from ion exchanger saturated from solutions, extraction of uranium from eluates obtained by desorption of it from ion exchangers saturated from pulp and solutions, reextraction of uranium from ELENITE crystals uraniltrikarbonata ammonium and calcination to obtain uranium oxide (Larin VK, Litvinenko VG New technological scheme processing of uranium ores // Mining Bulletin - 1998. - 3 - P. 32-34). This known method with the opening of raw materials by various methods optimizes the process of uranium extraction in terms of productivity and cost. Nevertheless, he does not use the possibilities of complex coordination of campaign and percolation processes in order to create a single effective technology. The main disadvantage of this method is the high consumption of ion exchanger. The latter is determined mainly by discharges of ion-exchange material with spent sorption pulp. In the panel sorption process, drainage nets with a mesh size of, as a rule, 0.6 mm are used to organize counterflow and separation of the ion exchange resin and the ore suspension. The smaller cell size significantly reduces the throughput of the sorption apparatus and, accordingly, the productivity of processing raw materials. During operation, the ion exchanger gradually wears out and decreases in size to the size of the cells of the separation (drainage) grids of the sorption apparatus. Further, he cannot participate in the process with countercurrent movement of pulp and ion exchanger. That is, in the case under consideration, the ion-exchange material is a waste for the sorption extraction of uranium from pulps.

 The technical result of the invention is to reduce the consumption of ion exchanger and the use of ion-exchange material extracted from spent sorption pulp after desiliconization for sorption of uranium from percolation leaching solutions and for ion-exchange treatment of recycled or waste water. This technical result is achieved by the fact that the processing of uranium ores is carried out by a method including crushing and wet grinding to produce pulp, thickening, acid agitation leaching, sorption of uranium from pulp, desorption of uranium from ion exchanger, saturated from pulp, deoxidation of ion exchanger, as well as acid percolation leaching , sorption of uranium from solutions, desorption of uranium from ion exchanger saturated from solutions, extraction of uranium from eluates obtained by desorption of it from ion exchanger saturated from pulp and solutions, reext uranium extraction with the release of crystals of ammonium uranyl tricarbonate and calcination to obtain uranium oxide, according to the invention, waste ion-exchange material with a size of 0.6-0.2 mm ≥95% is extracted from spent pulp of sorption, subjected to de-siliconization and used for sorption of uranium from percolation solutions leaching and for ion-exchange treatment of recycled or waste water.

 The process of sorption extraction of uranium from solution, in contrast to pulp sorption, allows the use of fine ion exchanger, for example, 0.6-0.2 mm. Isolation of the ion-exchange material for sorption from the pulps from the ore suspension can be carried out in various ways, one of which is screening. Studies have determined that the fine fractions of the ion exchanger operated in the pulps are the most silicified. As a result, the ion-exchange material extracted from the spent sorption pulp cannot be directly used for sorption of uranium from percolation leaching solutions.

 The latter is due to lower temperatures and uranium concentrations in the initial solutions compared to pulps, as well as the need to maintain higher kinetic characteristics of ion exchangers used in sorption pressure columns in relation to ion-exchange materials used in sorption packs.

 In the known method, as silicon accumulates on the ion exchanger operated in the pulp, it undergoes desiliconization, and all fractions of the ion-exchange material are sent to this operation simultaneously. Silicon removal is carried out by fluoride or, as a rule, alkaline sulfate solutions. For the effective regeneration of fine ion-exchange material isolated by screening from the pulp, in comparison with the desiliconization of other fractions of the ion exchanger, intensified processing conditions are required, primarily in terms of temperature and reagent concentrations. In this regard, desiliconization of the ion-exchange material trapped from the spent sorption pulp is carried out separately from the total mass of ion exchanger subjected to desiliconization.

 After autonomous desiliconization of the material, it is used for sorption of uranium from percolation leaching solutions or is used for ion-exchange treatment of recycled or waste water from the technological process for extracting uranium from ore raw materials. Impurities, such as molybdenum, which is effectively extracted from these media by ion-exchange material prepared by the above techniques, also accumulate in recycled waters, which include drains of the dehydration (thickening) operation of crushed ore, carbonate solutions of the uranium re-extraction process. Waste water, which is inevitably formed in the technological cycle of processing uranium ores, contains a wide range of elements - sulfate and nitrate ions, molybdenum, etc., which can be sorbed by the obtained ion exchanger.

The following are examples of processes for processing uranium ores using known and proposed technologies. During the industrial trials, the ore charge was processed, in which the uranium-bearing rocks were represented by trachidacites, andesite-basalts, felsites, conglomerates and granites; minerals of a valuable component - nasturan, coffinite, uranium mobile, brannerite, uranofan and uranotil. Ore was crushed and crushed to obtain pulp, which was thickened and subjected to sulfuric acid leaching in packs in the presence of manganese dioxide at pH 2.0-2.2, ORP 460-520 mV, temperature 60-65 ^o С. in ten steps with a countercurrent of ion exchanger and pulp. The content of ion exchange material in the apparatus was maintained at 9-10% by volume. The mesh size of the drainage nets in the apparatus was 0.6 mm. Uranium was desorbed from an ion exchanger saturated from pulp by sulfuric-nitric acid solutions. Upon accumulation of silicon ion exchange resin up to 35-40% by SiO _2, it was isolated from the ore suspension and subjected to deoxidation using alkaline sulfate solutions and reducing the SiO ₂ content on the ion exchanger by 5-10% of the accumulated amount.

 Percolation leaching of uranium was carried out by irrigation with sulphate solutions of coarse ore stacked in piles (dumps). The concentration of sulfuric acid in irrigation solutions was maintained at 1-3 g / l, so that the pH of productive percolation solutions was 1.7-2.2. Sorption of a valuable component from productive solutions of percolation leaching was carried out in SNK columns with Purolight anion exchanger, sorption mother liquors were reinforced with sulfuric acid and sent to ore irrigation.

Uranium was desorbed from an ion exchanger saturated from productive solutions with sulfuric acid solutions. The eluates obtained by desorption of uranium from ion exchangers saturated from pulp and solutions were combined and sent for extraction with an organic mixture of D2EHPA + TAA + TBP. Uranium was reextracted with solutions of carbon ammonium salts with the release of crystals of ammonium uranyl tricarbonate. The crystals were calcined in VGTP furnaces at a final process temperature of 850 ^o C. The finished product of the processing of uranium ore was uranium oxide-oxide.

 The implementation diagram of the technology according to the known method is shown in figure 1; on the proposed - figure 2.

 The difference between the new technology and the known one was the separation of waste sorption from the spent pulp, for the pulp process, of ion exchange material with a particle size of 0.6-0.2 mm ≥95%, its desiliconization and its use for loading into the sorption extraction of uranium from percolation leaching solutions, instead of the original ion exchange resin.

 Isolation of ion-exchange material from spent pulp was carried out by screening. The particle size distribution and kinetic characteristics of the ion exchanger used in the propagation scheme and isolated by screening from the spent pulp are given in Tables 1 and 2.

As can be seen from the data presented, the content of silicon dioxide in the waste ion-exchange material amounted to 43.4% versus 35.0% for the total mass of the sorbent used in the pulp process. Accordingly, the kinetic properties of fine ion exchanger are much lower. Desiliconization of the ion-exchange material extracted from the spent pulp was carried out with a solution of sodium hydroxide - 50 g / dm ³ and sodium sulfate - 35 g / dm ³ at a temperature of 40-45 ^o C and a processing time of 3 hours. The parameters specified in this case, the alkaline-sulfate treatment provided the necessary efficiency of desalination of ion exchange resin and high capacitive characteristics of the final product.

 The kinetics of sorption of uranium by the obtained ion-exchange material is presented in Table 3.

 Further, said ion exchange material was used to extract uranium from percolation solutions. Figure 1 and 2 presents a diagram of the known and proposed technologies for processing uranium ores. Their comparison shows that a new version of the process allows for a similar input of uranium with ore (1095 kg) to reduce the loss of ion exchanger from 48.9 to 35.2 kg, i.e. by 28.0%. The ion exchanger isolated from spent pulp and subjected to alkaline-sulfate treatment (desiliconization) can be used both for sorption extraction of uranium from percolation leaching solutions and for ion-exchange treatment of recycled or waste water generated during the processing of uranium ore raw materials.

 EXAMPLE of processing recycled water redistribution of thickening.

The circulating water of the redistribution of the thickening of the ore processing complex contained: U - 4 mg / dm ³ , Mo - 15 mg / dm ³ ; pH of the medium is 7.6.

When passing it through a sample of separated and de-siliconized ion exchanger at a rate of 10 volumes of solution per volume of ion exchanger per hour, the latter was saturated with uranium up to 33 g / dm ³ , molybdenum - up to 70 g / dm ³ . Molybdenum desorption was carried out with a solution, g / dm ³ :
NH ₄ OH - 90
(NH ₄ ) ₂ SO ₄ - 110
NH ₄ NO ₃ - 12
The obtained eluates contained molybdenum at a concentration of 8 g / dm ⁸ and were used for sorption concentration and the subsequent preparation of pure salts of molybdenum - ammonium polymolybdate, etc.

After conversion of the ion exchanger into the sulfate form with acidified water (pH 2-3), uranium was desorbed from it with a solution
H ₂ SO ₄ - 200 g / dm ³ , HNO ₃ - 5 g / dm ³ .

The resulting regenerates contained: U - 30 g / dm ³ , HNO ₃ - 70 g / dm ³ . These solutions were sent for extraction cleaning followed by the preparation of uranium oxide-uranium according to a known scheme.

 Thus, it is determined that the proposed ion exchanger can be used to extract uranium and molybdenum from the circulating water of the redistribution of the concentration of ore raw materials.

 EXAMPLE of processing a working solution of a redistribution of extraction.

 Obtaining finished products of a given quality at the ore processing complex requires the removal of impurities (molybdenum, etc.) accumulated in reverse carbonate solutions of stripping. This is accomplished by withdrawing 1/7 of the latter in each extraction-re-extraction cycle of uranium for rectification, followed by the supply of bottoms to the desorption eluates. But under these conditions, unlike iron, silicon, and other impurities, molybdenum is removed inefficiently due to coextraction with uranium, which requires the periodic withdrawal of part of the bottom residue solutions to the redistribution of agitation leaching of raw materials. This leads to an increase in the load on the introduction of components on hydrometallurgy and, ultimately, to a decrease in uranium extraction.

In laboratory conditions, an acidified bottoms residue of the composition was sent to ion exchange treatment:
Mo - 1.5 g / dm ³
U - 4.2 g / dm ³
pH - 2.5 units
As an ion-exchange material, an ion exchanger isolated from spent pulp was used, subjected to alkaline-sulfate treatment (desiliconization).

Successive sorption of molybdenum and uranium from these solutions was carried out with a drainage rate of 1 volume of solution per volume of ion exchanger per hour. The saturation of the ion exchanger by molybdenum was 42 g / dm ³ , by uranium - 39 g / dm ³ , sequential desorption with solutions of a composition similar to that given in the previous example, allowed to obtain
1. Molybdenum desorbate, g / dm ³ :
NH ₄ OH - 25
(NH ₄ ) ₂ SO ₄ - 120
Mo - 15
U - 3 • 10 ^-3
2. Uranium desorbate, g / dm ³ :
H ₂ SO ₄ - 80
HNO ₃ - 80
U - 35
Mo - 0.2
From these solutions, according to known schemes, conditioned commercial products of uranium and molybdenum were obtained. In the effluent solutions of the deoxidized bottoms (pH 2.5) after sorption, the residual content of the components was:
U - 2.9 mg / dm ³
Mo - less than 10 mg / dm ³
NO $\genfrac{}{}{0ex}{}{\text{-}}{\text{3}}$ - less than 1 mg / dm ³
The indicated concentrations of the components make it possible to direct these solutions to the tailing dump, bypassing the limits of leaching and sorption.

 EXAMPLE of waste water treatment.

The waste water of the ore processing complex, aimed at ion-exchange treatment, contained, mg / dm ³ :
U - 2
Mo - 3
NO $\genfrac{}{}{0ex}{}{\text{-}}{\text{3}}$ - 5
SO $\genfrac{}{}{0ex}{}{\text{-}}{\text{4}}$ - 100
The pH of the medium was 6.6 units.

The tested sample of ion exchanger - an analogue used in the previous example, was converted to OH ^- form. The rate of transmission of the solution through it was maintained by 10 m ³ / m ³ ion exchanger per hour.

When the LLP reached the solution volumes on the volume of the ion-exchange material, the content in it amounted to: U, Mo, NO ^- ₃ - cf., SO ^- ₄ - 50 mg / dm ³ .

The eluates obtained by desorption of saturated ion exchanger with solutions of a composition similar to previous experiments contained
1. Molybdenum desorbates, g / dm ³ :
(NH ₄ ) ₂ SO ₄ - 115
NH ₄ OH - 25
Mo - 5
2. Uranium desorbates, g / dm ³ :
H ₂ SO ₄ - 80
HNO ₃ - 25
U - 15
These molybdenum and uranium desorption eluates were sent for further processing. According to well-known schemes, conditional products were obtained from them: ammonium polymolybdate and uranium oxide. The desorption of sulfate ions from a saturated ion exchanger with 4% alkali made it possible to obtain eluates with a sodium sulfate content of 90 g / dm ³ , which were used as a protective additive during ionization desalination operations.

 In general, the materials presented show that the proposed method, compared with the known one, allows to reduce the consumption of ion exchanger during the processing of uranium ores, to reduce the content of impurities in the circulating and waste waters of the technological process, and to provide an additional release of conditioned commercial products.

Claims (1)

 A method of processing uranium ores, including crushing and wet grinding to produce pulp, thickening, acid agitation leaching, sorption of uranium from pulp, desorption of uranium from ionite saturated from pulp, desilination of ion exchanger, and acid percolation leaching, sorption of uranium from solutions, desorption from an ion exchanger saturated from solutions, extraction of uranium from eluates obtained by desorption of it from ion exchangers saturated from pulp and solutions, re-extraction of uranium with the release of crystals of ammonium uralnitricarbonate and calcining to obtain uranium oxide-oxide, characterized in that from the spent sorption pulp a waste ion-exchange material with a particle size of 0.6-0.2 mm ≥95% is isolated, subjected to de-siliconization and used for sorption of uranium from percolation leaching solutions and for ion-exchange treatment circulating or waste water.

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