A method for preparing diuranate by step-by-step precipitation

Abstract

The invention discloses a method for preparing diuranate by step-by-step precipitation, and the method comprises the following steps: step 1, dissolving unqualified diuranate with hydrochloric acid first, and then filtering to obtain an acid solution; step 2, heating the acid solution and adding a neutralizing precipitant and hydrogen peroxide, controlling the reaction temperature and pH value, and then aging and filtering to obtain a uranium purified solution and iron removal slag; step 3, adding a sodium hydroxide solution to the uranium purified solution, and then aging and filtering to obtain qualified sodium diuranate; step 4, adding a carbonate solution to the iron removal slag, controlling the reaction liquid-solid ratio, reaction temperature and pH value, and then filtering to obtain a uranium alkali leaching solution; step 5, adding a sodium hydroxide solution to the uranium alkali leaching solution, and then aging and filtering to obtain qualified sodium diuranate. The present invention aims to continue to extract qualified diuranate from unqualified diuranate to improve the recovery rate.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for preparing diuranate by step precipitation. Background Art

[0002] The existing invention patent with the publication number of CN115896492A discloses a method for separating and extracting uranium and beryllium from uranium-beryllium leaching solution, which discloses that uranium and beryllium are completely separated and purified, with a high recovery rate of uranium and beryllium, reducing the two leaching processes in the original uranium-beryllium leaching process, simplifying the process, and being able to fully recover valuable metals. And the existing invention patent with the publication number of CN111945001A discloses a method for treating monazite slag, which discloses that the separation of iron and uranium is carried out by extraction; but the existing separation of uranium and other metals cannot be used to solve the problem of continued recycling of unqualified diuranate products. Summary of the invention

[0003] The main purpose of the present invention is to provide a method for preparing diuranate by step precipitation, aiming to solve the technical problem that existing unqualified diuranate products cannot efficiently recover uranium.

[0004] To achieve the above object, the present invention provides a method for preparing diuranate by step-by-step precipitation, the method comprising the following steps:

[0005] Step 1, dissolving unqualified diuranate with hydrochloric acid, and then filtering to obtain an acid solution;

[0006] Step 2, heating the acid solution and adding a preset amount of a neutralizing precipitant and hydrogen peroxide, controlling the reaction temperature and pH value, and then performing aging and filtering to obtain a uranium purified solution and iron removal slag; wherein the reaction temperature is 85° C. to 90° C., and the reaction end point pH value is 3.2 to 3.5;

[0007] Step 3, adding a preset amount of sodium hydroxide solution to the purified uranium solution to precipitate the uranium, and then performing aging and filtering to obtain qualified sodium diuranate;

[0008] Step 4, adding a preset amount of carbonate solution to the iron removal slag, controlling the reaction liquid-solid ratio, reaction temperature and pH value, and then filtering to obtain uranium alkaline leaching solution;

[0009] Step 5: adding a preset amount of sodium hydroxide solution to the uranium alkaline leaching solution to precipitate the uranium, and then performing aging and filtering treatment to obtain qualified sodium diuranate.

[0010] Optionally, in step 1, the liquid-to-solid ratio of the acid dissolution reaction is (1.5-2.0) mL:1 g, the reaction time is 1 h-1.5 h, and the residual H+ concentration is 0.25 mol / L-0.50 mol / L.

[0011] Optionally, in step 2, the neutralizing precipitant is a sodium hydroxide solution with a mass fraction greater than or equal to 30%; and the mass fraction of hydrogen peroxide is less than 3%.

[0012] Optionally, in step 2, the aging time is 1.0 h-2.0 h.

[0013] Optionally, in step 3, the reaction temperature is 50°C-65°C, the reaction time is 2h-4h, and the pH value at the reaction endpoint is 7.0±0.2.

[0014] Optionally, in step 4, the reaction liquid-solid ratio is (4-6) mL: 1 g, the reaction time is 2 h to 4 h, the reaction temperature is 65±2° C., and the reaction endpoint pH is 10.0-10.5.

[0015] Optionally, in step 4, the carbonate solution is a mixed solution of (45±5) g / L Na2CO3 and (15±5) g / L NaHCO3.

[0016] Optionally, in step 5, the reaction time is 2.0 h to 4.0 h, the reaction temperature is 50° C. to 80° C., and the pH value at the reaction endpoint is 12.5 to 13.5.

[0017] Optionally, in step 1, the mass fraction of uranium in the unqualified diuranate is 30% to 45%, and the mass fraction of iron is 5% to 15%.

[0018] Optionally, in step 2, the mass fraction of uranium in the filter residue is 5% to 8%.

[0019] Beneficial effects:

[0020] (1) using hydrochloric acid to dissolve unqualified diuranate products, thereby dissolving iron impurities in the unqualified diuranate products, and removing iron from the acid solution by the goethite method, thereby removing iron from the solution by precipitation.

[0021] (2) Through seed induction and longer aging treatment, iron removal is more thorough and conducive to solid-liquid separation.

[0022] (3) Using carbonate as a leaching agent to extract and recover uranium from the iron removal slag, thereby improving the uranium recovery rate.

[0023] (4) Using sodium hydroxide to recover uranium from the uranium purification solution and the uranium alkaline leaching solution by precipitating uranium to obtain a qualified diuranate product.

[0024] (5) The present invention shortens the treatment process, making the treatment process simple, flexible and easy to operate, and can be used for large-scale production. It can also effectively reduce energy consumption and reagent consumption, thereby reducing cost investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a process flow chart of an embodiment of a method for preparing diuranate by step-by-step precipitation. DETAILED DESCRIPTION

[0026] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings.

[0028] Reference Figure 1 , is a preparation process of a method for preparing diuranate by step precipitation in one embodiment of the present invention, and the detailed process steps are as follows:

[0029] Step 1, dissolving unqualified diuranate with hydrochloric acid, and then filtering to obtain an acid solution.

[0030] Specifically, the unqualified diuranate sample refers to the one obtained from the hydrometallurgy of the co-existing uranium resources, which includes diuranate, and the mass fraction of uranium U is 30%-45%, and the mass fraction of iron Fe is 5%-15%. The acidolysis agent used in this embodiment is dilute hydrochloric acid, and the concentration is controlled at 1-2 mol / L, the purpose of which is to dissolve some soluble components in the unqualified diuranate under the action of hydrochloric acid; wherein, diuranate is soluble under acidic conditions, and impurity iron can also generate divalent iron under the action of hydrochloric acid, and after filtering, the acid solution after acidolysis and the part that is not easy to be acidolyzed and deposited in the filter residue can be obtained. The filter residue can be discarded as waste residue, and the acid solution can continue the subsequent extraction operation. At the same time, it is also necessary to control the liquid-solid ratio of the acid dissolution reaction, that is, to control the mass of the unqualified diuranate added and the total volume of the solution in the reactor. In this embodiment, the liquid-solid ratio is controlled to be (1.5-2.0) mL: 1 g; preferably, the reaction time of the acidolysis is controlled to be 1h-1.5h; more preferably, the residual H in the solution needs to be controlled. + The concentration is in the range of 0.25mol / L to 0.50mol / L.

[0031] Step 2, heating the acid solution and adding a preset amount of a neutralizing precipitant and hydrogen peroxide to control the reaction temperature and pH value.

[0032] Specifically, the neutralization precipitant added is a sodium hydroxide solution, and the mass fraction of sodium hydroxide is ≥30%, and the mass fraction of hydrogen peroxide added is less than 3% and greater than 0, and the heating temperature is controlled to 85°C to 90°C, and the pH value of the reaction end point is 3.2 to 3.5, so that the reaction environment of this step is a high-heat and low-acidity environment, and the iron removal method using the goethite method is realized, that is, the iron in the acid solution is removed under acidic conditions. The principle is that the divalent iron is first converted into trivalent iron under the action of hydrogen peroxide, and then the trivalent iron can generate β-FeOOH under high heat and low acid environment, that is, the formation of goethite crystals, so that the trivalent iron precipitation realizes the removal of iron in the solution. In addition, in order to further reduce the iron ion concentration of the solution after iron removal, all the products after the goethite method reaction can also be transferred to the aging tank, based on the precipitation generated in the aforementioned reaction, and then by aging reaction 1.0h-2.0h, the iron removal effect can be improved.

[0033] Preferably, 5%-10% of seed crystals can be reserved in the tank, and then the aging reaction is carried out for 1.0h-2.0h, so as to realize the treatment by seed crystal induction and aging, reduce the iron ion concentration of the solution after iron removal, and reduce the iron ion concentration of the solution after iron removal to 0.08mg / L, further improve the iron removal effect, and finally filter the solution to obtain uranium purified solution and iron removal slag. Generally, the mass fraction of uranium in the iron removal slag is 5%-8%, and uranium extraction can be further carried out.

[0034] Step 3, adding a preset amount of sodium hydroxide solution to the purified uranium solution to precipitate the uranium, and then aging and filtering to obtain qualified sodium diuranate. Specifically, adding a sodium hydroxide solution with a mass fraction greater than or equal to 30% to the purified uranium solution, so that the purified uranium solution and sodium hydroxide are neutralized and precipitated to achieve the purpose of recovering uranium, and in the reaction, the neutralization precipitation reaction time needs to be controlled to be 2.0h-4.0h, the temperature is 50℃-65℃, and the end point pH value is 7.0±0.2. After aging, filtering and filter cake washing, a qualified sodium diuranate product can be obtained.

[0035] Step 4, adding a preset amount of carbonate solution to the iron removal slag, controlling the reaction liquid-solid ratio, reaction temperature and pH value, and then filtering to obtain uranium alkaline leaching solution.

[0036] Specifically, carbonate is added to the iron removal slag to carry out alkaline leaching to extract uranium, wherein the carbonate solution is a mixed solution of (45±5) g / L Na2CO3 and (15±5) g / L NaHCO3, and the reaction liquid-solid ratio is controlled to be (4-6) mL:1 g, the reaction time is 2h-4h, the reaction temperature is 65±2°C, the pH value at the reaction end point is 10.0-10.5, and the dissolved solution obtained by filtration is a uranium alkaline leaching solution, and the uranium alkaline leaching solution is a sodium uranyl tricarbonate solution; the filter cake is pulped and washed to obtain leached slag, and the mass fraction of uranium in the slag is 0.5%-1.5%. This step realizes the leaching and extraction of uranium from the iron removal slag, and further improves the recovery rate of uranium.

[0037] Step 5: adding a preset amount of sodium hydroxide solution to the uranium alkaline leaching solution to precipitate the uranium, and then performing aging and filtering treatment to obtain qualified sodium diuranate.

[0038] Specifically, a NaOH solution of 30% or more is added to the uranium alkaline leaching solution to precipitate the uranium, wherein the precipitation reaction time is controlled to be 2.0h-4.0h, the temperature is 50°C-80°C, and the end point pH value is 12.5-13.5, and then the product is aged, filtered and the filter cake is washed to prepare a qualified sodium diuranate product. The quality of the sodium diuranate obtained above meets the requirements of the Technical Conditions for Diuranates (EJ / T803-93).

[0039] In this embodiment, unqualified diuranate is acid-lyzed, and iron is completely precipitated by the goethite method at high temperature and low pH value, and uranium is recovered from the obtained uranium purified solution and iron removal slag respectively; and carbonate is selected as a leaching agent, uranium is extracted and recovered from the iron removal slag to obtain a uranium alkaline leaching solution, and sodium hydroxide is used to recover uranium from the uranium purified solution and the uranium alkaline leaching solution respectively by precipitating uranium, and a qualified diuranate product is prepared, and the standard quality requirements are met. In addition, the entire treatment process is simple, flexible and easy to operate, easy to mass produce, and can effectively reduce energy consumption and reagent consumption, thereby reducing cost investment, and also realizing the effective recycling of diuranate.

[0040] Furthermore, in order to better illustrate the specific process of the present invention, samples of unqualified diuranate products from different batches are randomly taken and mixed evenly, and the following operations are performed in multiple groups respectively. The method of the present invention is further described below in conjunction with specific embodiments.

[0041] Example 1

[0042] Step 1, dissolving with hydrochloric acid.

[0043] Weigh 500 g of the above-mentioned unqualified diuranate sample (U: 39.37%, Fe: 7.07%) into a 2000 mL glass beaker, add 750 mL of industrial water, start stirring, add 110 mL of 31.12% HCl solution, control the acid dissolution reaction time to 1.5 h, filter to obtain the acid solution, wash the filter residue with 0.5 BV volume of washing water twice to obtain the dissolved residue, and discard the filter residue.

[0044] Step 2, the acid solution is treated to remove iron.

[0045] The acid solution was placed in a 2000mL glass beaker, stirred and heated, and 31% NaOH solution and 3% H2O2 solution were added, and the reaction temperature of the iron removal by the goethite method was controlled to be 87°C ± 2°C, the end point pH value was 3.5, and the time was 2.0h. All the iron removal liquid was then transferred to an aging tank, with 8% of seeds reserved in the tank, and the aging time was 1.5h; uranium purified liquid was obtained by hot filtration (material temperature ≥ 55°C), and the filter cake was iron removal slag, and the uranium mass fraction in the iron removal slag was U: 7.42%.

[0046] Step 3, preparing sodium diuranate by precipitation of the purified uranium solution.

[0047] A 31% by mass NaOH solution was added to the purified uranium solution to precipitate the uranium, and the neutralization precipitation reaction temperature was controlled to be 62°C ± 2°C, the end point pH value was 7.0, and the reaction time was 3.0 h. After aging, filtration and filter cake washing, a qualified sodium diuranate product was obtained.

[0048] Step 4, leaching the iron slag using alkaline method.

[0049] The above iron removal slag was placed in a 1000mL glass beaker, stirred and heated, and a mixed solution of 47g / L Na2CO3 and 12g / L NaHCO3 was added to the beaker, and the liquid-solid ratio of the alkaline leaching reaction was controlled to be 4mL:1g, the reaction time was 3.5h, the reaction temperature was 65±2℃, and the pH value of the reaction end point was 10.2. The filtered clear liquid was uranium alkaline leaching liquid, and the filter cake was pulped and washed to obtain leaching residue, which was alkaline leaching residue. The mass fraction of uranium in the alkaline leaching residue was U: 0.98%.

[0050] Step 5, preparing sodium diuranate by precipitation of uranium alkali leaching solution.

[0051] Add 31% NaOH solution by mass to the uranium alkaline leaching solution, control the precipitation reaction temperature to 75°C ± 2°C, the reaction endpoint pH value to 13.2, the reaction time to 3.0h, and then age, filter and wash the filter cake to prepare a qualified sodium diuranate product.

[0052] Furthermore, the two sodium diuranate products prepared by the above-mentioned step-by-step precipitation were mixed evenly, and samples were taken for analysis. The sodium diuranate product (on a dry basis) had U: 51.12%, SO4 2- :0.14%、PO4 3- : 0.15%, SiO2: 0.35%, F - :0.19%、Cl - : 0.26%, Fe: 0.37%, the product quality meets the requirements of "Technical Conditions for Diuranates".

[0053] Example 2

[0054] Step 1, dissolving with hydrochloric acid.

[0055] Weigh 500 g of the above-mentioned unqualified diuranate sample (U: 39.37%, Fe: 7.07%) into a 2000 mL glass beaker, add 750 mL of industrial water, start stirring, add 110 mL of 30.54% HCl solution, control the acid dissolution reaction time to 1.0 h, filter to obtain the acid solution, wash the filter residue with 0.5 BV volume of washing water twice to obtain the dissolved residue, and discard the filter residue.

[0056] Step 2, the acid solution is treated to remove iron.

[0057] The acid solution was placed in a 2000mL glass beaker, stirred and heated, and 31% NaOH solution and 2% H2O2 solution were added, and the reaction temperature of the iron removal by the goethite method was controlled to be 87°C ± 2°C, the end point pH value was 3.3, and the time was 1.0h. All the iron removal liquid was then transferred to an aging tank, with 5% of seeds reserved in the tank, and the aging time was 1.5h; uranium purified liquid was obtained by hot filtration (material temperature ≥ 55°C), and the filter cake was iron removal slag, and the mass fraction of uranium in the iron removal slag was U: 5.26%.

[0058] Step 3, preparing sodium diuranate by precipitation of the purified uranium solution.

[0059] Add 31% by mass NaOH solution to the purified uranium solution to precipitate the uranium, and control the neutralization precipitation reaction temperature to 60°C ± 2°C, the end point pH value to 7.1, and the reaction time to 2.5h. Then, after aging, filtering and filter cake washing, a qualified sodium diuranate product is obtained.

[0060] Step 4, leaching the iron slag using alkaline method.

[0061] The above iron removal slag was placed in a 1000mL glass beaker, stirred and heated, and a mixed solution of 47g / L Na2CO3 and 12g / L NaHCO3 was added to the beaker, and the liquid-solid ratio of the alkaline leaching reaction was controlled to be 5mL:1g, the reaction time was 3.0h, the reaction temperature was 65±2℃, and the pH value of the reaction end point was 10.4. The filtered clear liquid was uranium alkaline leaching liquid, and the filter cake was pulped and washed to obtain leaching residue, which was alkaline leaching residue. The mass fraction of uranium in the alkaline leaching residue was U: 0.84%.

[0062] Step 5, preparing sodium diuranate by precipitation of uranium alkali leaching solution.

[0063] Add 31% NaOH solution by mass to the uranium alkaline leaching solution, control the precipitation reaction temperature to 75°C ± 2°C, the reaction endpoint pH value to 13.0, the reaction time to 2.0h, and then age, filter and wash the filter cake to prepare a qualified sodium diuranate product.

[0064] Furthermore, the two sodium diuranate products prepared by the above-mentioned step-by-step precipitation were mixed evenly, and samples were taken for analysis. The sodium diuranate product (on a dry basis) had U: 54.81%, SO4 2 -: 0.10%, PO4 3- :0.18%, SiO2: 0.21%, F - :0.15%、Cl - : 0.14%, Fe: 0.18%, the product quality meets the requirements of "Technical Conditions for Diuranates".

[0065] Example 3

[0066] Step 1, dissolving with hydrochloric acid.

[0067] Weigh 500 g of the above-mentioned unqualified diuranate sample (U: 39.37%, Fe: 7.07%) into a 2000 mL glass beaker, add 750 mL of industrial water, start stirring, add 110 mL of 32.01% HCl solution, control the acid dissolution reaction time to 1.0 h, filter to obtain the acid solution, wash the filter residue with 0.5 BV volume of washing water twice to obtain the dissolved residue, and discard the filter residue.

[0068] Step 2, the acid solution is treated to remove iron.

[0069] The acid solution was placed in a 2000mL glass beaker, stirred and heated, and 31% NaOH solution and 2.5% H2O2 solution were added. The iron removal reaction temperature was controlled to be 87°C ± 2°C, the end point pH value was 3.4, and the time was 4.0h. The iron removal was carried out by the goethite method. All the iron removal liquid was then transferred to an aging tank, and 10% of the seeds were reserved in the tank. The aging time was 1.5h. The uranium purified liquid was obtained by hot filtration (material temperature ≥ 55°C). The filter cake was iron removal slag, and the uranium mass fraction in the iron removal slag was U: 6.62%.

[0070] Step 3, preparing sodium diuranate by precipitation of the purified uranium solution.

[0071] Add 31% NaOH solution by mass to the purified uranium solution to precipitate the uranium, and control the neutralization precipitation reaction temperature to 55°C ± 2°C, the end point pH value to 6.9, and the reaction time to 2.5h. Then, after aging, filtering and filter cake washing, a qualified sodium diuranate product is obtained.

[0072] Step 4, leaching the iron slag using alkaline method.

[0073] The above iron removal slag was placed in a 1000mL glass beaker, stirred and heated, and a mixed solution of 47g / L Na2CO3 and 12g / L NaHCO3 was added to the beaker, and the liquid-solid ratio of the alkaline leaching reaction was controlled to be 4.5mL:1g, the reaction time was 3.0h, the reaction temperature was 65±2℃, and the pH value at the reaction end point was 10.2. The acid solution obtained by filtration was the uranium alkaline leaching solution, and the filter cake was washed by pulping to obtain the leaching residue, which was the alkaline leaching residue, and the mass fraction of uranium in the alkaline leaching residue was U: 0.74%.

[0074] Step 5, preparing sodium diuranate by precipitation of uranium alkali leaching solution.

[0075] Add 31% NaOH solution by mass to the uranium alkaline leaching solution, control the precipitation reaction temperature to 75°C ± 2°C, the reaction endpoint pH value to 13.0, the reaction time to 2.5h, and then age, filter and wash the filter cake to prepare a qualified sodium diuranate product.

[0076] Furthermore, the two sodium diuranate products prepared by the above-mentioned step-by-step precipitation were mixed evenly, and samples were taken for analysis. The sodium diuranate product (on a dry basis) had U: 52.45%, SO4 2- :0.10%、PO4 3- :0.27%, SiO2: 0.41%, F - :0.18%、Cl - : 0.20%, Fe: 0.29%, the product quality meets the requirements of "Technical Conditions for Diuranates".

[0077] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0078] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0079] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing diuranate by stepwise precipitation, characterized in that: The method comprises the following steps: Step 1: Dissolve the unqualified diuranate with hydrochloric acid, and then filter to obtain an acid solution, wherein the unqualified diuranate is solid, the hydrochloric acid is liquid, the liquid-solid ratio of hydrochloric acid to the unqualified diuranate is (1.5-2.0) mL: 1 g, the reaction time is 1 h-1.5 h, and the residual H + The concentration is 0.25mol / L~0.50mol / L; Step 2, heating the acid solution and adding a preset amount of a neutralizing precipitant and hydrogen peroxide, controlling the reaction temperature and pH value, and then performing aging and filtering treatment to obtain a uranium purified solution and iron-removing slag; wherein the reaction temperature is 85° C. to 90° C., the pH value at the reaction end point is 3.2 to 3.5, wherein the neutralizing precipitant is a sodium hydroxide solution with a mass fraction greater than or equal to 30%; and the mass fraction of the hydrogen peroxide is less than 3%; Step 3, adding a preset amount of sodium hydroxide solution to the purified uranium solution to precipitate the uranium, and then performing aging and filtering treatment to obtain qualified sodium diuranate, wherein the reaction temperature is 50° C.-65° C., the reaction time is 2 h-4 h, and the reaction endpoint pH value is 7.0±0.2; Step 4, adding a preset amount of carbonate solution to the iron removal slag, controlling the reaction liquid-solid ratio, reaction temperature and pH value, and then filtering to obtain a uranium alkali leaching solution, the reaction liquid-solid ratio is (4-6) mL: 1 g, the reaction time is 2 h-4 h, the reaction temperature is 65 ± 2 ° C, and the reaction endpoint pH value is 10.0-10.5; Step 5, adding a preset amount of sodium hydroxide solution to the uranium alkaline leaching solution to precipitate the uranium, and then performing aging and filtering treatment to obtain qualified sodium diuranate, wherein the reaction time is 2.0h~4.0h, the reaction temperature is 50°C~80°C, and the reaction endpoint pH value is 12.5~13.

5.

2. The method for preparing diuranate by stepwise precipitation according to claim 1, characterized in that: In step 2, the aging time is 1.0 h to 2.0 h.

3. The method for preparing diuranate by stepwise precipitation according to claim 1, characterized in that: In step 4, the carbonate solution is a mixed solution of (45±5) g / L Na2CO3 and (15±5) g / L NaHCO3.

4. The method for preparing diuranate by stepwise precipitation according to any one of claims 1 to 3, characterized in that: In step 1, the mass fraction of uranium in the unqualified diuranate is 30% to 45%, and the mass fraction of iron is 5% to 15%.

5. The method for preparing diuranate by stepwise precipitation according to any one of claims 1 to 3, characterized in that: In step 2, the mass fraction of uranium in the iron-removing slag is 5% to 8%.

Images