Filtration aiding method for improving filtering efficiency of monazite excellent slag

Abstract

The invention discloses a filtering aid method for improving the filtering efficiency of monazite superior soluble slag, which comprises the following steps: step 1, carrying out solid-liquid separation on mixed slurry after alkali cake superior soluble callback to obtain filter residue 1 and filtrate 1; step 2, adding water into the filter residue 1, mixing and stirring according to a liquid-solid ratio of (1-2.5): 1 to react for 0.5-4 hours, and carrying out solid-liquid separation on ore pulp after the reaction to obtain a filter residue 2 and a filtrate 2; 3, if the ore pulp filtering speed in the step 2 is lower than 20 L / (m < 2 > * h) or the water content of obtained filter residues 2 is larger than 60%, the step 2 is repeated for the filter residues 2, the composite reducing agent with the preset mass is added, and stirring reaction is conducted for 2 hours till the water content of the filter residues is smaller than or equal to 60% or the ore pulp filtering speed in the plate and frame filtering process is larger than or equal to 20 L / (m < 2 > * h); in the step 3, the mass ratio of the added composite reducing agent to the original dry slag is (5-50) kg: 1t, and the composite reducing agent comprises sodium sulfite and thiourea in the mass ratio of (1-2): 1. The invention aims at shortening and improving the slag filtering performance so as to shorten the filtering time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of monazite processing, and particularly relates to a filter aid method for improving the filtering efficiency of monazite optimal dissolution residue. BACKGROUND

[0002] At present, monazite is a phosphate rare earth mineral and is one of the main raw materials for producing rare earth. For the processing of monazite rare earth concentrate, first, alkali decomposition and acid dissolution are used to generate alkali cake, and then the monazite alkali cake is further processed to obtain optimal dissolution residue. The existing processing of alkali cake is to perform acid dissolution on the alkali cake and add alkali slurry to adjust the pH value to 4-4.5, and then perform filtration. The residue after filtration is washed by using water to prepare a slurry, and the mixed slurry is subjected to solid-liquid separation. The washing and solid-liquid separation process is repeated for 2-3 times. The final solid residue is the optimal dissolution residue. However, in the washing process, the solid-liquid separation speed becomes slower after each washing, and with the progress of the reaction, the water content of the final optimal dissolution residue reaches 50-80%. In addition, a layer of fine mud is attached to the filter cloth after filtration, so that the filter cake is not shaped and is not convenient for subsequent application.

[0003] The existing patent with the patent number CN114107661A provides a method for improving the filtering performance of monazite optimal dissolution residue. The method is to obtain a leaching suspension by adding hydrochloric acid to the monazite optimal dissolution residue. The suspension is rich in valuable elements such as rare earth, uranium and thorium. Then, a certain amount of oxalic acid is added to the suspension, and the reaction temperature, time, residual acid and the amount of oxalic acid are controlled. In this way, the thorium element in the suspension is fully precipitated, and other impurities in the monazite optimal dissolution residue are also precipitated. Although the filtering performance is improved, the loss of rare earth is serious, the operation above 70 DEG C is forced, the high temperature dependence is strong, and the low filtration speed makes the filtration period too long, which cannot meet the needs of large-scale production. SUMMARY

[0004] The main purpose of the present application is to provide a filter aid method for improving the filtering efficiency of monazite optimal dissolution residue, which aims to solve the technical problem of poor filtering performance of monazite alkali cake when it is processed into optimal dissolution residue.

[0005] To achieve the above-mentioned purpose, the present application provides a filter aid method for improving the filtering efficiency of monazite optimal dissolution residue, which comprises the following steps:

[0006] Step 1: performing solid-liquid separation on the mixed slurry after optimal dissolution of the alkali cake, to obtain filter residue 1 and filtrate 1;

[0007] Step 2: adding water to the filter residue 1 and mixing and stirring the mixture at a liquid-solid ratio of 1-2.5:1 for 0.5-2 hours, and then performing solid-liquid separation on the slurry after the reaction to obtain filter residue 2 and filtrate 2;

[0008] Step 3: if the filtration speed of the slurry in step 2 is lower than 20 L / (m2·h), adding water to the filter residue 2 and mixing and stirring the mixture at a liquid-solid ratio of 1-2.5:1 for 0.5-2 hours, and then performing solid-liquid separation on the slurry after the reaction to obtain filter residue 3 and filtrate 3.2 h) or the water content of the filter residue 2 is greater than 60%, then the filter residue is repeated step 2, and a predetermined mass of a composite reducing agent is added to the mixed stirring reaction and stirred for 2 hours until the corresponding filter residue has a water content of less than or equal to 60% or the filter speed of the ore slurry during the plate and frame filtration process is greater than or equal to 20 L / (m 2 *h);

[0009] In step 3, the mass ratio of the added composite reducing agent to the original dry residue is (5-50) kg:1 t, and the composite reducing agent includes sodium sulfite and thiourea in a mass ratio of 1-2:1.

[0010] Optionally, in steps 2 and 3, the temperature of the stirring reaction is 25-40°C.

[0011] Optionally, in steps 1-3, the solid-liquid separation uses a plate and frame filter press, and the filtration pressure is 0.4-0.8 MPa.

[0012] Optionally, the method further comprises subjecting the filtrate 1 obtained in step 1 to aging treatment to oxidize the divalent iron to form iron hydroxide precipitate and remove it.

[0013] Optionally, before step 1, the method further comprises leaching the alkali cake with hydrochloric acid, then adding alkali slurry for mixing, and controlling the pH value of the mixed slurry to be 4-4.5 to make the tetravalent cerium in the alkali cake form hydroxide precipitate and the trivalent iron hydrolyze to form iron hydroxide precipitate, and the alkali slurry is a mixed solution prepared by adding water to the alkali cake.

[0014] Optionally, in step 3, the addition of the composite reducing agent causes the tetravalent cerium and the trivalent iron in the ore slurry to be reduced to trivalent cerium and divalent iron, respectively, and the thiourea and the sodium sulfite are oxidized to form a sulfuric acid complex salt precipitate.

[0015] Optionally, if the filter speed of the ore slurry in step 2 is less than 20 L / (m 2 *h), then the filter residue 2 is mixed with water and a composite reducing agent at a liquid-solid ratio of 1-2.5:1 and stirred for 2 hours, and the ore slurry after the reaction is subjected to solid-liquid separation to obtain corresponding filter residue 3 and filtrate 3, wherein the filter speed of the ore slurry is ≥20 L / (m 2 *h);

[0016] The obtained filter residue 3 is continuously subjected to solid-liquid separation until a filter cake with a thickness of ≥15 mm and a water content of ≤45% is obtained.

[0017] Optionally, if the water content of the filter residue 2 obtained in step 2 is greater than 60%, then the filter residue 2 is mixed with water and a composite reducing agent at a liquid-solid ratio of 1-2.5:1 and stirred for 2 hours, and the ore slurry after the reaction is subjected to solid-liquid separation to obtain corresponding filter residue 3 and filtrate 3;

[0018] If the moisture content of filter residue 3 is still greater than 60%, continue to add water and composite reducing agent to filter residue 3 and mix and stir at a liquid-solid ratio of 1-2.5:1 for 2 hours. Then, perform solid-liquid separation on the slurry after the reaction to obtain the corresponding filter residue 4 and filtrate 4.

[0019] If the moisture content of filter residue 4 is less than or equal to 60%, the obtained filter residue 4 will continue to undergo solid-liquid separation to obtain a filter cake with a thickness of ≥15mm and a moisture content of ≤45%.

[0020] Optionally, if the moisture content of the filter residue in step 2 is less than or equal to 60% or the slurry filtration rate is greater than or equal to 20 L / (m²), the filter residue can be filtered further. 2 If *h), then the corresponding filter residue will continue to undergo solid-liquid separation until a filter cake with a thickness ≥15mm and a moisture content ≤45% is obtained.

[0021] Optionally, the filtrate obtained in step 3 can be returned to step 2 for mixing and pulping.

[0022] Beneficial effects:

[0023] In this invention, by detecting whether the moisture content of the filter residue obtained after the previous solid-liquid separation and the filtration speed of the slurry meet the preset requirements, it is determined whether to add a composite reducing agent in the next water washing and stirring reaction. The corresponding slurry filtration speed or the moisture content of the filtered residue is also detected, thereby effectively controlling the timing of adding the composite reducing agent. The addition of the composite reducing agent can reduce the tetravalent cerium and trivalent iron in the original filter residue to trivalent cerium and divalent iron. At pH 4 to 4.5, both trivalent cerium and divalent iron are soluble. The sulfate ions generated after the oxidation of thiourea and sodium sulfite form sulfate double salt precipitates with thorium, iron and other ions. The sulfate double salt precipitates have large particles and low moisture content, making them easier to filter than cerium hydroxide and ferric hydroxide, thus achieving the control of the optimal slurry filtration efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic flowchart of the first embodiment of a filter aid method for improving the filtration efficiency of monazite slag.

[0025] Figure 2 for Figure 1 The corresponding process flow diagram for secondary pulping and washing and the addition of composite reducing agent;

[0026] Figure 3 for Figure 1 The flowchart of the corresponding three pulping and washing processes and the addition of composite reducing agent;

[0027] Figure 4 for Figure 1 The flowcharts for the corresponding secondary and tertiary pulping and washing processes, and the addition of composite reducing agents.

[0028] The objectives, functional features and advantages of the present application will be further illustrated in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] It should be understood that the specific embodiments described herein are merely exemplary and are not intended to limit the present application.

[0030] Referring to Figures 1-4 The present application provides a filter aid method for improving the filtering efficiency of monazite optimal-solubility residue, which comprises the following steps:

[0031] Step 1: solid-liquid separation is performed on the mixed slurry after the optimal-solubility cake is adjusted, to obtain filter residue 1 and filtrate 1. Specifically, the optimal-solubility cake includes rare earth hydroxide, undecomposed monazite, phosphate, Th / U compound, light rare earth (cerium group) oxide, etc., and the soluble hydroxide therein is easily leached by acid, and then the mixed slurry can be obtained by leaching the optimal-solubility cake with hydrochloric acid, followed by adding alkali slurry for mixing, and adjusting the pH value of the mixed slurry to 4-4.5, which aims to form hydroxide precipitate of tetravalent cerium, form hydroxide precipitate of thorium, and form hydroxide precipitate of trivalent iron in the mixed slurry, and the filter residue 1 obtained after filtration contains Th(OH)4, Ce(OH)4 and Fe(OH)3. In addition, the filtrate 1 is subjected to aging treatment to remove radioactive elements radium and reduce the radioactivity of chlorinated rare earth liquid.

[0032] Step 2: water is added to the filter residue 1 and mixed and stirred at a liquid-solid ratio of 1-2.5:1 for 0.5-2 hours, and then solid-liquid separation is performed on the slurry after the reaction, to obtain filter residue 2 and filtrate 2. The filtrate 2 still contains part of radioactive elements, which needs to be subjected to aging treatment.

[0033] Step 3: if the filtering speed of the slurry in step 2 is lower than 20 L / (m 2 *h) or the moisture content of the filter residue 2 is greater than 60%, the filter residue is subjected to step 2 again, and a preset mass of composite reducing agent is added in the mixing and stirring reaction and stirred for 2 hours; specifically, the mass ratio of the added composite reducing agent to the original dry residue is (5-50) kg:1 t, and preferably (6-17) kg:1 t.

[0034] Further, the composite reducing agent comprises sodium sulfite and thiourea in a mass ratio of 1-2:1. The thiourea and sodium sulfite as the reducing agent can reduce tetravalent cerium and trivalent iron into trivalent cerium and divalent iron. The trivalent cerium and divalent iron are both soluble at pH = 4-4.5. The sulfate ions generated after the oxidation of the thiourea and sodium sulfite form sulfate double salt precipitates with thorium ions and iron ions. The sulfate double salt precipitates have large particles and low water content, and are more easily filtered than cerium hydroxide, iron hydroxide, and thorium hydroxide. The filtrate obtained is returned to the once-washing and pulp-making in step 2. After the plate-and-frame filtration, the divalent iron in the filtrate is oxidized during the aging process to form iron hydroxide precipitates, which are filtered together with the decontamination residue to be removed. It can be seen that the addition of the composite reducing agent can reduce the insoluble tetravalent cerium, improve the cerium recovery rate, and improve the filtration speed. However, the addition of excessive reducing agent can introduce impurities such as sulfate and ammonia, affecting the quality of the chlorinated rare earth product. Therefore, the amount of the composite reducing agent needs to be strictly controlled.

[0035] Further, the temperature of the stirring reaction in the pulp washing is 25-40°C, which belongs to the room temperature environment and does not need to be heated, solving the dependence on temperature in the prior art.

[0036] Further, the plate-and-frame filter press is used in the solid-liquid separation operation, and the filtration pressure is 0.4-0.8 MPa.

[0037] Further, the aging time of the reduced divalent iron in the decontamination process can be extended. A small amount of hydrogen peroxide can also be added to shorten the aging time, so that the oxidized trivalent iron forms a precipitate and is filtered together with the decontamination residue.

[0038] Further, the alkali pulp in step 1 is a mixed solution prepared by adding water to the alkali cake.

[0039] Further, as shown in Figure 2 If the filtration speed of the ore slurry in step 2 is less than 20 L / (m 2 *h), the filter residue 2 is mixed with water and a preset amount of the composite reducing agent at a liquid-solid ratio of 1-2.5:1, stirred and reacted for 2 hours, and then the ore slurry after the reaction is subjected to solid-liquid separation to obtain corresponding filter residue 3 and filtrate 3. The filtration speed of the ore slurry is ≥20 L / (m 2 *h).

[0040] The obtained filter residue 3 is continuously subjected to solid-liquid separation until a filter cake with a thickness of ≥15 mm and a water content of ≤45% is obtained.

[0041] Further, as shown in Figure 4As shown, if the water content of the filter residue 2 obtained in step 2 is greater than 60%, the filter residue 2 is added with water, a preset amount of composite reducing agent and mixed and stirred at a liquid-solid ratio of 1-2.5:1 for 2 hours. The solid-liquid separation is performed on the slurry after reaction to obtain filter residue 3 and filtrate 3 corresponding thereto;

[0042] If the water content of the filter residue 3 is still greater than 60%, the filter residue 3 is continuously added with water, a preset amount of composite reducing agent and mixed and stirred at a liquid-solid ratio of 1-2.5:1 for 2 hours. The solid-liquid separation is performed on the slurry after reaction to obtain filter residue 4 and filtrate 4 corresponding thereto;

[0043] The water content of the filter residue 4 is detected to be less than or equal to 60%. The obtained filter residue 4 is continuously subjected to solid-liquid separation to obtain filter cake with a thickness of ≥15 mm and a water content of ≤45%.

[0044] Further, if the water content of the filter residue in the repeated step 2 operation is less than or equal to 60% or the slurry filtration speed is greater than or equal to 20 L / (m 2 *h), the corresponding filter residue is continuously subjected to solid-liquid separation until filter cake with a thickness of ≥15 mm and a water content of ≤45% is obtained.

[0045] Further, if the water content of the filter residue obtained after adding water and performing secondary plate and frame filtration on the corresponding filter residue is greater than 60% or the slurry filtration speed in the plate and frame filtration process is less than 20 L / (m 2 *h), a preset amount of composite reducing agent is also added when washing with water for the third time. The solid-liquid separation is performed on the slurry after reaction to obtain filter residue and filtrate, and the water content of the filter residue is less than or equal to 60% or the slurry filtration speed in the plate and frame filtration process is greater than or equal to 20 L / (m 2 *h). The corresponding filter residue is continuously subjected to solid-liquid separation until filter cake with a thickness of ≥15 mm and a water content of ≤45% is obtained. The specific schematic diagram is shown in Figure 3 .

[0046] In addition, in addition to the above-mentioned content, if the slurry filtration speed in step 1 is less than 20 L / (m 2 *h) or the water content of the obtained filter residue 1 is greater than 60%, a preset amount of composite reducing agent is added in the mixing and stirring reaction of step 2 and stirred for 2 hours to obtain filtrate 2' and filter residue 2' corresponding thereto. The water content of the filter residue 2' and the slurry filtration speed are continuously detected. If the water content of the filter residue 2' is less than or equal to 60% and the slurry filtration speed is greater than 20 L / (m 2 *h), the obtained filter residue 2' is continuously subjected to solid-liquid separation until filter cake with a thickness of ≥15 mm and a water content of ≤45% is obtained. However, if the slurry filtration speed is still less than 20 L / (m 2h) or the water content of the filter residue 2' is greater than 60%, the filter residue 2' is repeated step 2, and a predetermined mass of the composite reducing agent is added to the mixed stirring reaction and stirred for 2 hours until the corresponding filter residue water content is less than or equal to 60% or the slurry filtration speed is greater than or equal to 20L / (m 2 h).

[0047] In summary, in the present application, the water content of the filter residue obtained after the previous solid-liquid separation and whether the slurry filtration speed meets the predetermined requirements are detected, and then it is determined whether to add the composite reducing agent in the next water washing stirring reaction, and the corresponding slurry filtration speed or the water content of the filter residue after filtration is detected, thereby effectively controlling the timing of adding the composite reducing agent, and the tetravalent cerium and trivalent iron in the original filter residue are reduced to trivalent cerium and divalent iron, and at pH = 4-4.5, both trivalent cerium and divalent iron are soluble, and the sulfate ions generated after the oxidation of thiourea and sodium sulfite form sulfate double salt precipitates with thorium and iron ions, and the sulfate double salt precipitate particles are large and have low water content, which is easier to filter than cerium hydroxide and iron hydroxide, thereby realizing the control of the optimal-soluble slag filtration efficiency.

[0048] Further, in order to better illustrate the process operation of the present application, the following is described by specific examples.

[0049] Example 1

[0050] The monazite ore is used as the Rio Tinto ore, the corresponding monazite cake is obtained after alkali decomposition of the concentrate, and then the cake is leached with hydrochloric acid, and the pH is adjusted to 4 by adding alkali slurry and optimal-soluble slag, and the mixed slurry is subjected to solid-liquid separation to obtain filter residue 1 and filtrate 1. The filter residue 1 is mixed with water at a liquid-solid ratio of 2:1 and stirred for 2 hours, and the slurry after reaction is subjected to plate and frame filtration to obtain filter residue 2 and filtrate 2. The filter residue 2 is about 5mm thick slurry, and the water content of the filter residue 2 is 76%, and the filtration speed in the foregoing filtration is 8L / (m 2 h), and the weight of the slag in the slurry is about 3t, and then the filter residue 2 is added with water and 33kg of sodium sulfite and 17kg of thiourea, and the liquid-solid ratio is controlled to 2:1 for stirring reaction for 2 hours, and the slurry after reaction is subjected to plate and frame filtration, and the filtration speed is detected to be 30L / (m 2 h), and the plate and frame filtration is continued to obtain a plate and frame filter cake with a thickness of about 18mm, and the filter cake is hard, and the water content of the filter cake is 45%. The reaction process schematic diagram can be seen from Figure 2 .

[0051] Example 2

[0052] The monazite ore is used as a low terbium and dysprosium ore, and after alkali decomposition of the concentrate, the corresponding monazite alkali cake is obtained, and after hydrochloric acid leaching and adding alkali slurry to adjust the pH to 4, the mixed slurry is subjected to solid-liquid separation to obtain filter residue 1 and filtrate 1, water is added to the filter residue 1 and mixed and stirred at a liquid-solid ratio of 1.5:1 for 0.5 hours, and the reaction slurry is subjected to plate and frame filtration to obtain filter residue 2 and filtrate 2, the water content of the filter residue 2 is detected to be less than or equal to 60%, water is continuously added and mixed and stirred at a liquid-solid ratio of 1.5:1 for 2 hours, and the reaction slurry is subjected to plate and frame filtration to obtain filter residue 3 and filtrate 3, the filter residue 3 is about 10mm thick slurry, and the water content of the filter residue 3 is detected to be 31%, and the filtration speed in the foregoing filtration is 10L / (m 2 *h), and the weight of the slurry in the slurry is about 3t, and then water is continuously added to the filter residue 3 and sodium sulfite 15kg and thiourea 15kg are added, and the liquid-solid ratio is controlled to be 1.5:1 for mixing and stirring for 2 hours, and the reaction slurry is subjected to plate and frame filtration to obtain filter residue 4 and filtrate 4, and the filtration speed is detected to be 24L / (m 2 *h), and plate and frame filtration is continuously used to obtain a plate and frame filter cake with a thickness of about 15mm and a water content of 42%. The reaction process schematic diagram can be seen from Figure 3 .

[0053] Example 3

[0054] The monazite ore is used as a low terbium and dysprosium ore, and after alkali decomposition of the concentrate, the corresponding monazite alkali cake is obtained, and after hydrochloric acid leaching and adding alkali slurry to adjust the pH to 4, the mixed slurry is subjected to solid-liquid separation to obtain filter residue 1 and filtrate 1, water is added to the filter residue 1 and mixed and stirred at a liquid-solid ratio of 1.5:1 for 0.5 hours, and the reaction slurry is subjected to plate and frame filtration to obtain filter residue 2 and filtrate 2, the water content of the filter residue 2 is detected to be less than or equal to 60%, water is continuously added and mixed and stirred at a liquid-solid ratio of 1.5:1 for 2 hours, and the reaction slurry is subjected to plate and frame filtration to obtain filter residue 3 and filtrate 3, the filter residue 3 is about 10mm thick slurry, and the water content of the filter residue 3 is detected to be 31%, and the filtration speed in the foregoing filtration is 10L / (m 2 *h), and the weight of the slurry in the slurry is about 3t, and then water is continuously added to the filter residue 3 and sodium sulfite 15kg and thiourea 15kg are added, and the liquid-solid ratio is controlled to be 1.5:1 for mixing and stirring for 2 hours, and the reaction slurry is subjected to plate and frame filtration to obtain filter residue 4 and filtrate 4, and the filtration speed is detected to be 24L / (m 2 *h), and plate and frame filtration is continuously used to obtain a plate and frame filter cake with a thickness of about 15mm and a water content of 42%. The reaction process schematic diagram can be seen from Figure 3 .

[0055] It should be noted that, in this text, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or system that includes a list of elements not only includes those elements, but also includes other elements not expressly listed, or inherent to such process, method, article or system. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of other identical elements in the process, method, article or system that includes the element.

[0056] The above-mentioned embodiment numbers of the application are only for description, not representing the advantages and disadvantages of the embodiments.

[0057] The above is only the preferred embodiment of the application, and does not limit the patent scope of the application. Any equivalent structure or equivalent process transformation made by using the content of the application specification and drawings, or directly or indirectly applied in other related technical fields, is also included in the patent protection scope of the application.

Claims

1. A method for improving the filtration efficiency of monazite overslurry, characterized in that, The method comprises the following steps: Step 1, the mixed slurry after the base cake is optimally dissolved is subjected to solid-liquid separation to obtain filter residue 1 and filtrate 1; Step 2, water is added to the filter residue 1 and mixed and stirred at a liquid-solid ratio of 1-2.5:1 for 0.5-2 hours, and the reaction slurry is subjected to solid-liquid separation to obtain filter residue 2 and filtrate 2; Step 3, if the slurry filtration speed in step 2 is less than 20 L / (m 2 *h) or the moisture content of the filter residue 2 is greater than 60%, the filter residue is repeated step 2, and a predetermined mass of a composite reducing agent is added in the mixed stirring reaction and stirred for 2 hours until the corresponding filter residue moisture content is less than or equal to 60% or the slurry filtration speed in the plate and frame filtration process is greater than or equal to 20 L / (m 2 *h); In step 3, the mass ratio of the added composite reducing agent to the original dry residue is (5-50) kg:1 t, and the composite reducing agent comprises sodium sulfite and thiourea at a mass ratio of 1-2:

1.

2. The filter aid method for improving the filtration efficiency of the monazite-rich pregnant leach residue according to claim 1, characterized in that, In steps 2 and 3, the stirring reaction temperature is 25-40°C.

3. The filter aid method for improving the filtration efficiency of the monazite-rich pregnant leach residue according to claim 1, characterized in that, In steps 1-3, the solid-liquid separation is performed by using a plate-and-frame filter press, and the filtration pressure is 0.4-0.8 MPa.

4. The filter aid method for improving the filtration efficiency of the monazite-rich pregnant leach residue according to claim 1, wherein The method further comprises subjecting the filtrate 1 obtained in step 1 to aging treatment to oxidize the divalent iron into iron hydroxide precipitate and remove it.

5. The filtration efficiency improving method of the upgraded monazite- rich pregnant leach residue according to any one of claims 1 to 4, characterized by, Before step 1, the method further comprises leaching the base cake with hydrochloric acid, then adding base slurry for mixing, and controlling the pH value of the mixed slurry to be 4-4.5 to make the tetravalent cerium in the base cake form hydroxide precipitate and the trivalent iron hydrolyze to form iron hydroxide precipitate, and the base slurry is a mixed solution prepared by adding water to the base cake.

6. The filter aid method for improving the filtration efficiency of the monazite-rich pregnant leach residue according to claim 5, characterized in that, In step 3, the addition of the composite reducing agent reduces the tetravalent cerium and the trivalent iron in the slurry into trivalent cerium and divalent iron respectively, and oxidizes the thiourea and sodium sulfite to generate sulfuric acid complex salt precipitate.

7. The filter aid method for improving the filtration efficiency of the monazite-rich pregnant leach residue according to claim 5, wherein If the filtration speed of the ore slurry in step 2 is less than 20 L / (m 2 *h), the filter residue 2 is mixed with water and a composite reducing agent at a liquid-solid ratio of 1-2.5:1 and stirred for 2 hours. After the reaction, the ore slurry is subjected to solid-liquid separation to obtain filter residue 3 and filtrate 3, wherein the filtration speed of the ore slurry is ≥20 L / (m 2 *h). The obtained filter residue 3 is continuously subjected to solid-liquid separation until filter cake with a thickness of ≥15 mm and a water content of ≤45% is obtained.

8. The filter aid method for improving the filtration efficiency of the monazite-rich pregnant leach residue according to claim 5, wherein If the water content of the filter residue 2 obtained in step 2 is greater than 60%, the filter residue 2 is added with water and a composite reducing agent and mixed and stirred at a liquid-solid ratio of 1-2.5:1 for 2 hours, and the reaction slurry is subjected to solid-liquid separation to obtain corresponding filter residue 3 and filtrate 3; If it is detected that the water content of the filter residue 3 is still greater than 60%, the filter residue 3 is continuously added with water and a composite reducing agent and mixed and stirred at a liquid-solid ratio of 1-2.5:1 for 2 hours, and the reaction slurry is subjected to solid-liquid separation to obtain corresponding filter residue 4 and filtrate 4; If the water content of the filter residue 4 is less than or equal to 60%, the obtained filter residue 4 is continuously subjected to solid-liquid separation until filter cake with a thickness of ≥15 mm and a water content of ≤45% is obtained.

9. The filter aid method for improving the filtration efficiency of the monazite-rich pregnant leach residue according to claim 5, wherein If the water content of the filter residue in the operation of step 2 is less than or equal to 60% or the filter speed of the ore pulp is greater than or equal to 20 L / (m 2 *h), the corresponding filter residue will continue to be separated into solid and liquid until a filter cake with a thickness of ≥ 15 mm and a water content of ≤ 45% is obtained.

10. The filtration efficiency of the upgraded monazite overslag filtration method according to any one of claims 6 to 9, characterized by, The filtrate obtained in step 3 is returned to step 2 for mixing and slurry preparation.

Images