Method for extracting uranium from monazite high-density acid-soluble ore pulp

Abstract

The invention discloses a method for extracting uranium from monazite high-density acid-soluble ore pulp, which comprises the following steps: adding a surfactant into the acid-soluble ore pulp, and sequentially carrying out aging and separation treatment to obtain supernate and underflow ore pulp; carrying out plate-frame filter pressing on the underflow ore pulp to obtain insoluble slag and filter pressing clear liquid; mixing and conveying the supernate and the pressure filtration clear liquid to a uranium resin exchange tower for uranium adsorption to obtain uranium saturated resin and adsorption tail liquid; the uranium saturated resin is eluted through a washing solution, and eluted qualified liquid and lean resin are obtained; heating the leaching qualified liquid, adding sodium sulfate, carrying out heat preservation reaction after the sodium sulfate is completely dissolved, adjusting the pH value of the solution to be 1.5-2 all the time, and carrying out solid-liquid separation to obtain uranium precipitation mother liquor and precipitation iron slag; and adding a sodium hydroxide solution into the uranium precipitation mother liquor to adjust the pH value to 7-8, and filtering to obtain sodium diuranate precipitation. The method aims at improving the uranium extraction rate in the monazite concentrate acid-soluble ore pulp.

Description

Technical Field

[0001] The invention relates to the technical field of monazite smelting, and in particular to a method for extracting uranium from monazite high-density acid-soluble slurry. Background Art

[0002] Due to the complexity of the composition of monazite minerals and molten slag, the composition of hydrochloric acid acid-soluble slurry is complex. Generally, the acid-soluble slurry obtained by hydrochloric acid dissolution of monazite and molten slag usually has a high content of silicon, zirconium, and titanium colloids, which are enriched to form a large amount of muddy slag with small particle size and high viscosity, that is, the content of insoluble matter is high, and it is difficult to directly extract uranium from the acid-soluble slurry with complex composition. Although the use of slurry adsorption technology can avoid the problem of acid-soluble slurry being difficult to filter, due to the high density of acid-soluble slurry and the high content of insoluble matter, when too much slag is enriched in the resin adsorption tower, the colloid wrapping on the resin surface leads to a decrease in adsorption capacity, a slow flow rate of the feed liquid, agglomeration of the resin, and an increase in pipeline pressure, and the adsorption capacity is greatly reduced, and it is still difficult to achieve efficient separation and extraction of uranium.

[0003] The existing invention patent with the patent publication number CN111004920A discloses a method for smelting and separating uranium, thorium and rare earth from monazite molten slag. The method uses hydrochloric acid to dissolve the molten slag, and the upper turbid liquid is extracted by extraction to separate iron and uranium after dense aging. However, due to the high impurity content and complex composition of the upper turbid liquid during the extraction process, the uranium loss in the uranium iron rare earth extraction and stripping process is large, and the impurity content remains high, so it is difficult to promote large-scale industrialization. Furthermore, a method for extracting uranium from monazite high-density acid-soluble slurry with resin is proposed to solve the above problems. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for extracting uranium from monazite high-density acid-soluble slurry, aiming to solve the technical problem of low uranium extraction rate in existing monazite concentrate.

[0005] To achieve the above object, the present invention provides a method for extracting uranium from a high-density acid-soluble slurry of monazite, the method comprising the following steps:

[0006] Step 1, adding a surfactant to the acid-soluble slurry and stirring, and performing aging and separation treatments in sequence to obtain a supernatant and an underflow slurry, wherein the acid-soluble slurry is prepared by adding a hydrochloric acid solution to an alkali cake and monazite slag for dissolution, wherein the alkali cake is obtained after alkali decomposition treatment of monazite concentrate, and the monazite slag is a slag containing rare earth and uranium produced during the treatment of monazite concentrate;

[0007] Step 2, subjecting the underflow slurry to plate and frame filter pressing to obtain insoluble slag and filter press clear liquid;

[0008] Step 3, mixing the supernatant liquid with the filter press clear liquid and transporting it to a uranium resin exchange tower to perform a uranium adsorption operation to obtain a uranium saturated resin and an adsorption tail liquid;

[0009] Step 4, eluting the uranium saturated resin with an acidic washing solution to decompose the uranium, thereby obtaining a qualified elution solution and a lean resin, wherein the qualified elution solution contains iron and uranium;

[0010] Step 5, heating the qualified elution solution and adding sodium sulfate, and keeping the temperature to react after the sodium sulfate is completely dissolved, adjusting the pH value of the solution to always be maintained at 1.5-2, and performing solid-liquid separation to obtain uranium precipitation mother liquor and iron precipitation slag;

[0011] Step 6, slowly adding sodium hydroxide solution to the uranium precipitation mother solution and controlling the pH value of the solution to be 7-8, and filtering to obtain sodium diuranate precipitate.

[0012] Optionally, the surfactant includes one or more polyether surfactants.

[0013] Optionally, in step 1, the residual acid H in the acid-dissolved slurry + The concentration is 0.3-0.6mol / L.

[0014] Optionally, in step 1, the mass ratio of the volume of the acid-soluble slurry to the surfactant is 10000 L: (3-7) kg.

[0015] Optionally, in step 1, a thickener is used for separation and the supernatant is siphoned off.

[0016] Optionally, in step 4, the washing liquid is an aqueous solution with a pH value greater than 1.5.

[0017] Optionally, in step 5, the mass of the added sodium sulfate is 1.5-3 times the mass of the iron element in the qualified elution solution.

[0018] Optionally, in step 5, the pH value of the solution is adjusted to always be maintained at 1.5-2 by using alkali or alkaline oxide.

[0019] Optionally, in step 5, the qualified elution solution is heated to 75-95°C.

[0020] Beneficial effects:

[0021] The present invention is to add a surfactant to an acid-soluble slurry, siphon the supernatant after aging, and obtain a filter press clear liquid and an insoluble residue through a plate and frame filter press respectively. The problem that the acid-soluble slurry is difficult to filter in the slurry adsorption process is solved. At the same time, the supernatant obtained by siphoning and the filter press clear liquid of the plate and frame filter press can be directly passed through a uranium resin exchange tower to perform a uranium adsorption operation, thereby obtaining a uranium saturated resin, thereby avoiding the problem that after too much slag is enriched in the resin adsorption tower, the colloid wrapping on the resin surface leads to a decrease in adsorption capacity, a slow flow rate of the feed liquid, agglomeration of the resin, an increase in pipeline pressure, a greatly reduced adsorption capacity, and it is difficult to efficiently obtain a qualified leaching solution. The qualified leaching solution is further treated with sodium sulfate to remove impurities, and finally a high-purity sodium diuranate product is obtained. The uranium extraction method is simple, convenient and easy to operate, and can be easily promoted for industrial use. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic flow diagram of an embodiment of a method for extracting uranium from a high-density acid-soluble monazite slurry according to the present invention;

[0023] Figure 2 for Figure 1 The flow chart shown.

[0024] 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. DETAILED DESCRIPTION

[0025] 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.

[0026] See also Figure 1-2 The present invention provides a schematic flow diagram of a method for extracting uranium from a high-density acid-soluble slurry of monazite, the method comprising the following steps:

[0027] Step 1: adding the diluted surfactant to the acid-soluble slurry, and obtaining a supernatant and an underflow slurry after aging and separation.

[0028] Specifically, the surfactant includes one or more of polyether surfactants, such as one or more of polyoxyethylene ether surfactants. The acid-soluble slurry is prepared by adding hydrochloric acid solution to the alkali cake and monazite slag, and the ratio of the volume of the hydrochloric acid solution to the dry weight of the alkali cake and monazite slag is controlled to be (1-3) m 3 :1t, preferably 2.5m 3 :1t, and the solubility of the added hydrochloric acid is controlled at 2mol / L-10mol / L, that is, 35% concentrated hydrochloric acid is used to dilute and configure the corresponding concentration. The specific preparation process is to use hydrochloric acid to dissolve the alkali cake-excellent slag, and control the stirring reaction for 2-3 hours, the reaction temperature is 60℃-90℃, and finally control the residual acid H at the end of the reaction.+ About 0.3-0.6 mol, Cl- is greater than 4 mol / L.

[0029] Further, the surfactant is added to the acid-soluble slurry and stirred evenly, and the volume ratio of the acid-soluble slurry to the mass ratio of the surfactant is controlled to be 10000L: (3-7) kg, and then aged to achieve silica gel coagulation in the acid-soluble slurry and improve the solid-liquid separation performance. The mechanism is based on the spiral structure of the surfactant, which can connect the colloid and suspended particles in the acid-soluble slurry solution into a loose, network-like aggregate through bridging action, and based on the fact that the molecules of the surfactant are quite long, exceeding the action distance of the van der Waals force and the double layer force between the particles, so that the macromolecules of the active agent will be like a bridge, bridging on two or more particles, and act with the particles with their own active groups, thereby connecting the colloidal particles to form flocculent group deposition. Among them, the surfactant reaction time is generally 30 minutes, and separation is carried out after aging. Preferably, after thickening by a thickener for half an hour, the supernatant can be siphoned.

[0030] Furthermore, the alkali cake is obtained after alkali decomposition of monazite concentrate, and the monazite slag is the slag containing rare earth and uranium produced during the treatment of monazite concentrate. The acid-soluble slurry obtained after the alkali cake and the monazite slag are dissolved in hydrochloric acid usually has a high content of silicon, zirconium, and titanium colloids, forming a large amount of muddy slag with small particle size and high viscosity.

[0031] Step 2: The underflow pulp is subjected to plate and frame filter pressing to obtain insoluble residue and filter press clear liquid. The underflow pulp is subjected to plate and frame filter pressing to obtain insoluble residue and filter press clear liquid, and the filter press clear liquid enters the adsorption stock liquid collection tank for standby use.

[0032] Step 3, the supernatant and the filter press clear liquid are mixed and transported to the uranium resin exchange tower to perform uranium adsorption operation, and the uranium saturated resin and adsorption tail liquid are obtained after the resin is saturated with adsorption. Specifically, the supernatant and the filter press clear liquid are transported to the adsorption stock liquid collection tank for standby use. When the uranium adsorption operation is required, the adsorption stock liquid in the adsorption stock liquid collection tank is pumped into the uranium resin exchange tower from the lower part of the uranium resin exchange tower, and is adsorbed upward with the resin in the tower. After the adsorption is completed, the adsorption tail liquid flows out from the upper part of the uranium resin exchange tower, and the adsorption saturated resin is discharged from the bottom of the tower and enters the transfer tank for treatment.

[0033] Step 4: The uranium saturated resin is eluted with a washing liquid to desorb uranium to obtain a qualified elution liquid and a lean resin, wherein the qualified elution liquid contains iron and uranium. Specifically, the washing liquid is an aqueous solution with a pH value greater than 2, and after multiple elutions, a qualified elution liquid and a lean resin can be obtained. The lean resin is returned to the uranium resin exchange tower for reuse.

[0034] Step 5, heat the qualified leaching solution and add sodium sulfate, keep the temperature for reaction after the sodium sulfate is completely dissolved, adjust the pH value in the solution to always maintain 1.5-2, and then separate the solid and liquid to obtain the uranium precipitation mother solution and the iron precipitate slag. Specifically, heat the qualified leaching solution to above 75°C, preferably 75-95°C, and then control the mass of the added sodium sulfate to be 1.5-3 times the mass of the iron element in the qualified leaching solution, and adjust the pH value in the solution to within the range of 1.5-2 by sodium hydroxide, react for 2 hours, separate the solid and liquid, and obtain the uranium precipitation mother solution and the iron precipitate slag, respectively, wherein the specific reaction process is as follows:

[0035] 6FeCl3+4Na2SO4+12H2O→Na2Fe6(SO4)4(OH) 12 ↓+18Cl - +12H + +6Na + .

[0036] Step 6, slowly add sodium hydroxide solution to the uranium precipitation mother solution and control the solution pH value to 7-8, and obtain a sodium diuranate precipitate after filtering. The reaction process is as follows:

[0037] 2UO2 2+ +2Na + +6OH-=Na2U2O7↓+3H2O.

[0038] The present invention improves the solid-liquid separation performance of the acid-soluble slurry by adding a surfactant to the acid-soluble slurry, solves the problem that the acid-soluble slurry is difficult to filter in the slurry adsorption process, and at the same time, the supernatant obtained by siphoning is mixed with the filter press clear liquid obtained by plate and frame filter pressing and can be directly passed through a uranium resin exchange tower to perform uranium adsorption operations, thereby obtaining uranium saturated resin and adsorption tail liquid. The clear liquid adsorption process avoids the situation that after too much slag is enriched in the resin adsorption tower, the colloid coating on the resin surface causes the adsorption capacity to decrease, the flow rate of the feed liquid slows down, the resin agglomerates, the pipeline pressure increases, the adsorption capacity is greatly reduced, and it is difficult to efficiently obtain a qualified leaching solution. The qualified leaching solution is further treated with sodium sulfate to remove impurities, and finally a high-purity sodium diuranate product is obtained.

[0039] Further, in order to better illustrate the process and effect of a method for extracting uranium from a high-density acid-soluble slurry of monazite, the following is described in detail through specific examples, the details are as follows:

[0040] Example 1

[0041] Use 35% concentrated hydrochloric acid to dilute and prepare a hydrochloric acid leaching agent with a concentration of 6 mol / L. The volume of the hydrochloric acid leaching agent and the dry weight of the alkali cake and monazite slag are 2.5 m 3 : 1t, stirring reaction for 3 hours, reaction temperature 90 ° C, after the reaction to obtain acid soluble slurry.

[0042] The volume of acid-soluble slurry added to the surfactant mass ratio is 10000L:5kg, among which the acid-soluble slurry has an acidity of 0.44mol / L, a U concentration of 1.2g / L, a Cl concentration of 181.2g / L, and a Si content of 3.4g / L. After stirring and aging for 30 minutes, the acid-soluble slurry is siphoned by the thickener and the supernatant enters the adsorption stock solution collection tank. After the bottom flow passes through the plate and frame filter press, the filter press clear liquid enters the adsorption stock solution collection tank, and the supernatant and the filter press clear liquid are mixed to form the adsorption stock solution. The acidity of the adsorption stock solution is 0.44mol / L, the U concentration is 1.2g / L, the Si content is 0.056g / L, and the content of impurity silica gel is greatly reduced.

[0043] The adsorption raw liquid enters the adsorption tower from the bottom of the adsorption tower through the pump, and adsorbs upward with the resin in the tower. After the adsorption is completed, the adsorption tail liquid flows out from the top of the adsorption tower. The adsorption saturated resin is discharged from the bottom of the tower and enters the transfer tank. The low-acid aqueous solution (pH: 1.5) is used for elution. After the elution is completed, the qualified elution liquid obtained is transferred to the qualified liquid storage tank. The uranium concentration of the qualified elution liquid is 6.82g / L and the iron concentration is 3.31g / L. The lean resin returns to the resin adsorption tower for the next stage of adsorption.

[0044] The qualified elution solution was heated to 90°C, and sodium sulfate with a mass of 2.5 times the iron concentration was added, and the pH was adjusted to 1.6 by sodium hydroxide. After 2 hours of reaction, the solid and liquid were separated to obtain uranium precipitation mother liquor and iron precipitate slag. The uranium concentration of the uranium precipitation mother liquor was 6.78g / L and the iron concentration was 0.094g / L. Sodium hydroxide was added to the uranium precipitation mother liquor until the pH value of the solution was 7-8, and yellow cake was obtained by filtration. After analysis, the uranium content of the yellow cake was 70.4% and the iron content was 0.75%, which was a qualified sodium diuranate product.

[0045] Example 2

[0046] Use 35% concentrated hydrochloric acid to dilute and prepare a hydrochloric acid leaching agent with a concentration of 6 mol / L. The volume of the hydrochloric acid leaching agent and the dry weight of the alkali cake and monazite slag are 2.5m 3 : 1t, stirring reaction for 3 hours, reaction temperature 90 ° C, after the reaction to obtain acid soluble slurry.

[0047] The volume of acid-soluble slurry added to the surfactant mass ratio is 10000L:3kg, wherein the acid-soluble slurry has an acidity of 0.44mol / L, a U concentration of 1.2g / L, and a Si content of 3.4g / L. After stirring, the aging reaction is carried out for 30 minutes. The supernatant of the acid-soluble slurry enters the adsorption stock solution collection tank through the thickener. After the bottom flow passes through the plate and frame filter press, the filter press clear liquid enters the adsorption stock solution collection tank. The U concentration in the adsorption stock solution is 1.2g / L, and the Si content is 0.125g / L, which realizes the precipitation of most of the silica gel suspension.

[0048] The adsorption raw liquid enters the adsorption tower from the bottom of the adsorption tower through the pump, and adsorbs upward with the resin in the tower. After the adsorption is completed, the adsorption tail liquid flows out from the top of the adsorption tower. The adsorption saturated resin is discharged from the bottom of the tower and enters the transfer tank. The low-acid aqueous solution (pH=2) is used for elution. The qualified elution liquid obtained after the elution is completed is transferred to the qualified liquid storage tank. The uranium concentration of the qualified elution liquid is 6.29g / L, and the iron concentration is 3.11g / L. The resin returns to the resin adsorption tower for the next stage of adsorption.

[0049] The qualified elution solution was heated to 80°C, and sodium sulfate twice the mass of iron was added, and the pH was adjusted to 1.7 by sodium hydroxide. After 2 hours of reaction, the solid and liquid were separated to obtain uranium precipitation mother liquor and iron precipitate slag. The uranium concentration of the uranium precipitation mother liquor was 6.26g / L, and the iron concentration was 0.18g / L. Sodium hydroxide was added to the uranium precipitation mother liquor to a solution pH of 7-8, and yellow cake was filtered. After analysis, the yellow cake had a uranium content of 65.8% and an iron content of 0.65%, which was a qualified sodium diuranate product.

[0050] Example 3

[0051] Use 35% concentrated hydrochloric acid to dilute and prepare a hydrochloric acid leaching agent with a concentration of 6 mol / L. The volume of hydrochloric acid leaching agent is 2.5 m3 / L, and the dry weight of alkali cake and monazite slag is 2.5 m3 / L. 3 : 1t, stirring reaction for 2 hours, reaction temperature 90 ° C, after the reaction to obtain acid soluble slurry.

[0052] The volume of acid-soluble slurry added to the surfactant mass ratio is 10000L:7kg. U concentration is 1.2g / L, and Si content is 3.4g / L. After stirring and aging for 30 minutes, the acid-soluble slurry enters the adsorption stock solution collection tank through the supernatant of the thickener. After the bottom flow passes through the plate and frame filter press, the filter press clear liquid enters the adsorption stock solution collection tank. The clear liquid acidity is 0.44mol / L, the U concentration is 1.2g / L, and the Si content is 0.057g / L, which realizes the precipitation of most of the silica gel suspension.

[0053] The adsorption raw liquid enters the adsorption tower from the bottom of the adsorption tower through the pump, and adsorbs upward with the resin in the tower. After the adsorption is completed, the adsorption tail liquid flows out from the top of the adsorption tower. The adsorption saturated resin is discharged from the bottom of the tower and enters the transfer tank. The low-acid aqueous solution (pH=2) is used for elution. After the elution is completed, the qualified elution liquid obtained is transferred to the qualified liquid storage tank. The uranium concentration of the qualified elution liquid is 6.82g / L, and the iron concentration is 2.98g / L. The lean resin returns to the resin adsorption tower for the next stage of adsorption.

[0054] The qualified elution solution was heated to 85°C, and sodium sulfate 3 times the mass of iron was added. The pH was adjusted to 1.9 by sodium hydroxide. After 2 hours of reaction, the solid and liquid were separated to obtain uranium precipitation mother liquor and iron precipitate slag. The uranium concentration of the uranium precipitation mother liquor was 6.51g / L, and the iron concentration was 0.066g / L. Sodium hydroxide was added to the uranium precipitation mother liquor to a solution pH of 7-8, and yellow cake was obtained by filtration. After analysis, the yellow cake had a uranium content of 67.3% and an iron content of 0.54%, which was a qualified sodium diuranate product.

[0055] 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.

[0056] 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.

[0057] 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 extracting uranium from high-density acid-soluble monazite slurry, characterized in that: The method comprises the following steps: Step 1, adding a surfactant to an acid-soluble slurry, and performing aging and separation treatments in sequence to obtain a supernatant and an underflow slurry, wherein the acid-soluble slurry is prepared by adding a hydrochloric acid solution to an alkali cake and monazite slag for dissolution, wherein the alkali cake is obtained after alkali decomposition treatment of monazite concentrate, and the monazite slag is a rare earth-containing and uranium-containing slag produced during the treatment of monazite concentrate; Step 2, subjecting the underflow slurry to plate and frame filter pressing to obtain insoluble slag and filter press clear liquid; Step 3, mixing the supernatant liquid with the filter press clear liquid and transporting it to a uranium resin exchange tower to perform a uranium adsorption operation to obtain a uranium saturated resin and an adsorption tail liquid; Step 4, eluting the uranium saturated resin with a washing liquid to desorb uranium to obtain a qualified elution liquid and a lean resin, wherein the qualified elution liquid contains iron and uranium; Step 5, heating the qualified elution solution and adding sodium sulfate, and keeping the temperature to react after the sodium sulfate is completely dissolved, adjusting the pH value of the solution to always be maintained at 1.5-2, and performing solid-liquid separation to obtain uranium precipitation mother liquor and iron precipitation slag; Step 6, slowly adding sodium hydroxide solution to the uranium precipitation mother solution and controlling the pH value of the solution to be 7-8, and filtering to obtain sodium diuranate precipitate.

2. The method for extracting uranium from monazite high-density acid-soluble slurry according to claim 1, characterized in that: In step 1, the surfactant includes one or more polyether surfactants.

3. The method for extracting uranium from monazite high-density acid-soluble slurry according to claim 1, characterized in that: In step 1, the residual acid H in the slurry is dissolved by acid. + The concentration is 0.3-0.6mol / L.

4. The method for extracting uranium from monazite high-density acid-soluble slurry according to claim 1, characterized in that: In step 1, the volume ratio of the acid-soluble slurry to the mass ratio of the surfactant is 10000 L: (3-7) kg.

5. The method for extracting uranium from monazite high-density acid-soluble slurry according to claim 1, characterized in that: In step 1, separation is performed using a thickener and the supernatant is siphoned off.

6. The method for extracting uranium from monazite high-density acid-soluble slurry according to claim 1, characterized in that: In step 4, the washing liquid is an aqueous solution with a pH value greater than 1.

5.

7. The method for extracting uranium from monazite high-density acid-soluble slurry according to claim 1, characterized in that: In step 5, the mass of the added sodium sulfate is 1.5-3 times the mass of the iron element in the qualified elution solution.

8. The method for extracting uranium from monazite high-density acid-soluble slurry according to claim 7, characterized in that: In step 5, the pH value of the solution is adjusted to be always maintained at 1.5-2 by using alkali or alkaline oxide.

9. The method for extracting uranium from monazite high-density acid-soluble slurry according to claim 7, characterized in that: In step 5, the qualified elution solution is heated to 75-95°C.

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