A pretreatment method for mixed rare earth concentrate

Abstract

The present invention discloses a pretreatment method for a mixed rare earth concentrate, comprising: performing ore phase transformation on the mixed rare earth concentrate, oxidizing part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate into tetravalent cerium ions, and obtaining an ore phase transformation product containing tetravalent cerium ions; cooling the ore phase transformation product under air to complete the pretreatment of the mixed rare earth concentrate. The pretreatment method for a mixed rare earth concentrate provided by the present invention can realize the transformation of part of the trivalent cerium ions in the fluorocarbon cerium rare earth into tetravalent cerium ions, and make the tetravalent cerium ions exist in the form of CeO2, so that CeO2 and trivalent non-cerium rare earth in the ore phase transformation product finally obtained after pretreatment can be effectively separated by leaching treatment with an acid solution, providing a basis for realizing the effective separation of cerium rare earth and non-cerium rare earth, and improving the recovery rate of high-value non-cerium trivalent rare earth.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth ore dressing, and in particular relates to a pretreatment method for mixed rare earth concentrate. Background Art

[0002] Rare earth is a general term for 17 elements, including 15 lanthanide elements, scandium and yttrium. Due to its special electron layer structure, rare earth has excellent performance in light, electricity, magnetism and other aspects. With the continuous progress of science and technology, people have a deeper understanding of the basic theory of rare earth, and rare earth has also been applied in many fields such as hydrogen storage materials, petroleum catalysis, and permanent magnetic materials.

[0003] Rare earth is an important strategic resource in my country, and the reserves of mixed rare earth in Bayan Obo are the largest in the world. It is an important rare earth raw material in my country and is of great significance to the development of my country's rare earth industry. In the current production process, the high-temperature roasting decomposition process of concentrated sulfuric acid and the decomposition process of concentrated alkali solution are mainly used. In recent years, the treatment of "three wastes" in the rare earth concentrate smelting industry and the comprehensive utilization of resources such as fluorine and phosphorus have become research hotspots. The resulting mineral disposal methods are almost all integration and improvement of past smelting processes. Although each has its own characteristics, they are all based on the technical orientation of extracting all rare earth elements.

[0004] Since the rare earth elements in the Bayan Obo rare earth minerals are mainly light rare earths such as lanthanum, cerium, praseodymium, and neodymium, and in the back-end applications, the consumption of praseodymium and neodymium is large, the market gap is also large, and lanthanum is basically balanced. This has caused an oversupply and large backlog of cerium products. Therefore, in the smelting process of the Bayan Obo rare earth minerals, rare earth elements are combined for extraction and development. This excess production capacity formed to extract high-value resources (praseodymium and neodymium) cannot be eradicated for a long time.

[0005] In summary, how to provide a method that can achieve the selective extraction and balanced development of non-cerium rare earths (praseodymium, neodymium, lanthanum, etc.) is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a pretreatment method for mixed rare earth concentrate.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for pretreating a mixed rare earth concentrate, comprising:

[0009] Performing mineral phase transformation on the mixed rare earth concentrate to oxidize part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate into tetravalent cerium ions, thereby obtaining a mineral phase transformation product containing tetravalent cerium ions;

[0010] The mineral phase conversion product is cooled under air to complete the pretreatment of the mixed rare earth concentrate.

[0011] Optionally, the mixed rare earth concentrate is subjected to ore phase conversion, so that part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate is oxidized into tetravalent cerium ions, and an ore phase conversion product containing tetravalent cerium ions is obtained, including:

[0012] After the mixed rare earth concentrate is fed into the ore phase conversion reactor, air is continuously introduced into the bottom of the ore phase conversion reactor and the air is used as fluidizing gas to keep the mixed rare earth concentrate in a fluidized state;

[0013] The heating temperature of the ore phase conversion reactor is adjusted so that the mixed rare earth concentrate in a fluidized state is heated at a temperature of 500-700°C for 7-70 minutes to oxidize the trivalent cerium ions in the fluorocarbon cerium rare earth to generate cerium oxide, thereby completing the oxidation reaction of converting part of the trivalent cerium ions in the fluorocarbon cerium rare earth into tetravalent cerium ions.

[0014] Optionally, the ore phase conversion reactor heats the mixed rare earth concentrate to 500-650° C. for 10-60 minutes.

[0015] Optionally, the gas flow rate of air introduced into the bottom of the mineral phase conversion reactor is 400-500 mL / min.

[0016] Optionally, the mixed rare earth concentrate with a particle size of less than 0.038 mm accounts for at least 96% of the total weight of the mixed rare earth concentrate.

[0017] Optionally, the rare earth oxide REO grade in the mixed rare earth concentrate is 50%~65%; wherein RE includes Ce, La, Pr, Nd, Sm, Eu and Gd.

[0018] Optionally, the REO in the mixed rare earth concentrate includes the following components and their weight proportions are: La 2 O 3 28.15 parts, CeO 2 51.14 copies, Pr 6 O 11 4.79 parts, Nd 2 O 3 13.98 copies, Sm 2 O 3 0.99 parts, Eu 2 O 3 0.18 parts, Gd 2 O 3 0.39 parts.

[0019] Optionally, the mixed rare earth concentrate includes 2.72 parts of carbon.

[0020] Optionally, the mixed rare earth concentrate is subjected to ore phase conversion, so that part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate is oxidized into tetravalent cerium ions, and an ore phase conversion product containing tetravalent cerium ions is obtained, including:

[0021] The mineral phase transformation of the fluorocarbon cerium rare earth is determined according to the carbon content in the mixed rare earth concentrate, and when the carbon content in the mixed rare earth concentrate is 0, the mineral phase transformation reaction of the mixed rare earth concentrate is stopped.

[0022] Optionally, the mineral phase conversion product is cooled to 25° C. under air to complete the cooling treatment of the mineral phase conversion product.

[0023] The present invention provides a pretreatment method for a mixed rare earth concentrate, which comprises the following steps: performing ore phase transformation on the mixed rare earth concentrate, oxidizing part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate into tetravalent cerium ions, and obtaining an ore phase transformation product containing tetravalent cerium ions; and then cooling the ore phase transformation product under air to complete the pretreatment of the mixed rare earth concentrate, thereby realizing the conversion of part of the trivalent cerium ions in the fluorocarbon cerium rare earth into tetravalent cerium ions, so that the tetravalent cerium ions are in the form of CeO 2 exists in the form of CeO 2 The trivalent non-cerium rare earth can be effectively separated from the cerium rare earth by leaching treatment with an acid solution. It can be seen that the pretreatment method of the mixed rare earth concentrate provided in the present application not only has the advantages of simple operation, pollution-free and low cost, but also can provide a basis for the effective separation of cerium rare earth and non-cerium rare earth, thereby improving the recovery rate of high-value non-cerium trivalent rare earth.

[0024] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a flowchart of a method for pretreating a mixed rare earth concentrate according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] The present invention provides a method for pretreating a mixed rare earth concentrate, comprising the following steps:

[0029] Step 1: performing mineral phase transformation on the mixed rare earth concentrate to oxidize part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate into tetravalent cerium ions, thereby obtaining a mineral phase transformation product containing tetravalent cerium ions;

[0030] Step 2: Cool the mineral phase conversion product under air to complete the pretreatment of the mixed rare earth concentrate.

[0031] Since the cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate are trivalent cerium ions, and the trivalent cerium ions can undergo an oxidation reaction to generate tetravalent cerium ions, so that the obtained mineral phase conversion product is insoluble in tetravalent cerium ions in acid solution, and since the trivalent non-cerium elements in the mixed rare earth concentrate are easily soluble in acid solution, therefore, by oxidizing part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate into tetravalent cerium ions, the mineral phase conversion product containing tetravalent cerium ions can be leached through an acid solution, thereby realizing the separation of tetravalent cerium ions and trivalent non-cerium elements, and further realizing the selective extraction and balanced development of non-cerium rare earths, so that high-value non-cerium rare earth resources can be protected.

[0032] In this embodiment, the mixed rare earth concentrate is subjected to ore phase transformation, so that part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate is oxidized into tetravalent cerium ions, and an ore phase transformation product containing tetravalent cerium ions is obtained; and the ore phase transformation product is then cooled in air to complete the pretreatment of the mixed rare earth concentrate, so that part of the trivalent cerium ions in the fluorocarbon cerium rare earth is converted into tetravalent cerium ions, and the tetravalent cerium ions are converted into CeO 2 exists in the form of CeO 2 The trivalent non-cerium rare earth can be effectively separated from the cerium rare earth by leaching treatment with an acid solution. It can be seen that the pretreatment method of the mixed rare earth concentrate provided in the present application not only has the advantages of simple operation, pollution-free and low cost, but also can provide a basis for the effective separation of cerium rare earth and non-cerium rare earth, thereby improving the recovery rate of high-value non-cerium trivalent rare earth.

[0033] In some possible embodiments, the mixed rare earth concentrate in step 1 is subjected to mineral phase transformation, so that part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate is oxidized into tetravalent cerium ions to obtain a mineral phase transformation product containing tetravalent cerium ions, comprising the following steps:

[0034] Step 101: After the mixed rare earth concentrate is fed into the ore phase conversion reactor, air is continuously introduced into the bottom of the ore phase conversion reactor and the air is used as a fluidizing gas to keep the mixed rare earth concentrate in a fluidized state;

[0035] Step 102: Adjust the heating temperature of the ore phase conversion reactor so that the mixed rare earth concentrate in a fluidized state is heated at a temperature of 500 to 700° C. for 7 to 70 minutes to oxidize the trivalent cerium ions in the fluorocarbon cerium rare earth to generate cerium oxide, thereby completing the oxidation reaction of converting part of the trivalent cerium ions in the fluorocarbon cerium rare earth into tetravalent cerium ions.

[0036] It should be noted that the inner wall of the ore phase conversion reactor is provided with a heating wire, which is used to heat the mixed rare earth concentrate so that the temperature of the mixed rare earth concentrate reaches 500-700°C.

[0037] Here, the ore phase conversion reactor may be a roasting furnace. When the mixed rare earth concentrate is fed into the ore phase conversion reactor, the mixed rare earth concentrate is placed in a quartz tube, and then the quartz tube is placed in the roasting furnace.

[0038] In step 101, by using air as the fluidizing gas, part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate can be directionally converted into tetravalent cerium ions, while the non-cerium rare earth elements in the mixed rare earth concentrate will not be oxidized by the air. Therefore, by using air as the fluidizing gas, after the mixed rare earth concentrate is roasted in an air atmosphere, part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate can be directionally converted into tetravalent cerium ions, thereby achieving effective separation of cerium rare earth and non-cerium rare earth, thereby improving the recovery rate of high-value non-cerium trivalent rare earth.

[0039] The reaction formula of the decomposition reaction of fluorocarbon cerium rare earth in the mixed rare earth concentrate in the fluidized state under air atmosphere is: 6CeCO 3 F+O 2 →4CeO 2 +2CeF 3 +6CO 2 ↑; It can be seen that part of the trivalent cerium ions in the fluorocarbon cerium rare earth are directional converted into tetravalent cerium ions. It can be understood that after the fluorocarbon cerium rare earth is oxidized, part of it generates CeF 3 , and the other part generates CeO 2 Therefore, the generated CeO 2The tetravalent cerium ions in the cerium fluoride can be considered to be the directional transformation of part of the trivalent cerium ions in the cerium fluoride rare earth.

[0040] In this embodiment, air is continuously introduced into the bottom of the mineral phase conversion reactor and used as fluidizing gas to keep the mixed rare earth concentrate in the mineral phase conversion reactor in a fluidized state, thereby increasing the heat transfer efficiency of the mineral phase conversion reactor to the mixed rare earth concentrate, thereby promoting the decomposition efficiency of the fluorocarbon cerium rare earth during the fluidized roasting process; the heating temperature of the mineral phase conversion reactor is then adjusted so that the fluorocarbon cerium rare earth in the mixed rare earth concentrate in a fluidized state undergoes an oxidation reaction at a temperature of 500 to 700°C, so that the trivalent cerium ions in the fluorocarbon cerium rare earth undergo an oxidation reaction under the action of oxygen in the air to generate cerium oxide, thereby completing the oxidation reaction of some trivalent cerium ions in the fluorocarbon cerium rare earth into tetravalent cerium ions.

[0041] In some possible embodiments, the ore phase conversion reactor heats the mixed rare earth concentrate to 500-650° C. for 10-60 minutes.

[0042] Here, when the mixed rare earth concentrate is at a temperature of 500-650°C and the fluidized roasting time is 10-60 minutes, the fluorocarbon cerium in the mixed rare earth concentrate reacts with the oxygen in the air, so that the phase transformation rate of the fluorocarbon cerium is fast and the conversion rate is high. Therefore, the heating temperature of the fluidized roasting of the mixed rare earth concentrate is selected as 500-650°C, and the heating time of the roasting is selected as 10-60 minutes. Of course, the corresponding ranges of the fluidized roasting temperature and the heating time are determined by the inventor through a large number of experiments. Controlling them within an appropriate range can fully reduce the cost while achieving the best performance.

[0043] In this embodiment, the mixed rare earth concentrate is fluidized roasted at a temperature of 500-650°C for 10-60 minutes to complete the phase transformation of fluorocarbon cerium in the mixed rare earth concentrate, which can increase the phase transformation rate of fluorocarbon cerium in the mixed rare earth concentrate and improve the phase conversion rate of fluorocarbon cerium.

[0044] In some possible embodiments, the gas flow rate of air introduced into the bottom of the mineral phase conversion reactor is 400-500 mL / min.

[0045] Here, the gas flow rate of air may be any one of, but not limited to, 400 mL / min, 420 mL / min, 440 mL / min, 460 mL / min, and 500 mL / min.

[0046] In this embodiment, by introducing air at a gas flow rate of 400 to 500 mL / min into the bottom of the ore phase conversion reactor, the mixed rare earth concentrate can be kept in full contact with oxygen in the air, thereby increasing the phase conversion rate of fluorocarbon cerium in the mixed rare earth concentrate.

[0047] In some possible embodiments, the mixed rare earth concentrate with a particle size of less than 0.038 mm accounts for at least 96% of the total weight of the mixed rare earth concentrate.

[0048] In this embodiment, by selecting the particle size of more than 96% of the total weight of the mixed rare earth concentrate to be below 0.04 mm, the mixed rare earth concentrate can be kept in a fluidized state under the action of the air flow, and the surface of the mixed rare earth concentrate can be kept in contact with the oxygen in the air, thereby increasing the phase conversion rate of fluorocarbon cerium ore in the mixed rare earth concentrate.

[0049] In some possible embodiments, the rare earth oxide REO grade in the mixed rare earth concentrate is 50%~65%; wherein RE includes Ce, La, Pr, Nd, Sm, Eu and Gd.

[0050] Here, the mixed rare earth concentrate may be the Bayan Obo mixed rare earth ore, and the REO grade of the Bayan Obo mixed rare earth ore is 50% to 65%.

[0051] It should be noted that Ce, La, Pr, Nd, Sm, Eu and Gd are mainly distributed in fluorocarbon cerium ore and monazite, among which La, Pr, Nd, Sm, Eu and Gd are all non-cerium rare earth elements, and La, Pr, Nd, Sm, Eu and Gd will not be oxidized with oxygen; therefore, the present application can realize the directional conversion of only part of the trivalent cerium ions of the fluorocarbon cerium ore in the mixed rare earth concentrate into tetravalent cerium ions by fluidizing the mixed rare earth concentrate with air as the fluidizing gas, and the non-cerium rare earth elements in the mixed rare earth concentrate will not be oxidized, which provides a basis for the effective separation of cerium rare earth and non-cerium rare earth, so as to improve the recovery rate of high-value non-cerium trivalent rare earth.

[0052] In some possible embodiments, the REO in the mixed rare earth concentrate includes the following components and their weight proportions: La 2 O 3 27.11~29.15 parts, CeO 2 50.10~52.35 parts, Pr 6 O 11 4.62~4.88 parts, Nd 2 O 3 12.38~14.99 parts, Sm 2 O 3 0.81~1.19 parts, Eu 2 O3 0.08~0.29 parts, Gd 2 O 3 0.25~0.51 parts.

[0053] As a preferred embodiment, REO in the mixed rare earth concentrate includes the following components and their weight proportions are: La 2 O 3 28.15 parts, CeO 2 51.14 copies, Pr 6 O 11 4.79 parts, Nd 2 O 3 13.98 copies, Sm 2 O 3 0.99 parts, Eu 2 O 3 0.18 parts, Gd 2 O 3 0.39 parts.

[0054] Here, La 2 O 3 , Pr 6 O 11 、Nd 2 O 3 、Sm 2 O 3 、Eu 2 O 3 and Gd 2 O 3 All of them are trivalent non-cerium rare earths, and these trivalent non-cerium rare earths are easily soluble in acid, thus providing a basis for the separation between the above-mentioned trivalent non-cerium rare earths and the acid-insoluble cerium rare earth ore treated by the present application.

[0055] In some possible embodiments, the mixed rare earth concentrate contains 2.72 parts of carbon.

[0056] Here, the carbon in the mixed rare earth concentrate can be understood as the content of carbon element in the mixed rare earth concentrate.

[0057] In some possible embodiments, a mixed rare earth concentrate is subjected to a mineral phase transformation, so that part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate is oxidized into tetravalent cerium ions to obtain a mineral phase transformation product containing tetravalent cerium ions. The method also includes: judging the mineral phase transformation of the fluorocarbon cerium rare earth according to the carbon content in the mixed rare earth concentrate, and stopping the mineral phase transformation reaction of the mixed rare earth concentrate when the carbon content in the mixed rare earth concentrate is 0.

[0058] It should be noted that the monitoring of the carbon content in the mixed rare earth concentrate here can be determined by the carbon dioxide content in the mineral phase conversion reactor. Specifically, when there is no carbon dioxide in the mineral phase conversion reactor, it means that all the carbon in the mixed rare earth concentrate has reacted to generate carbon dioxide, and the carbon dioxide has been discharged from the mineral phase conversion reactor. Therefore, the fluorocarbon cerium rare earth is completely decomposed at this time to complete the mineral phase conversion reaction.

[0059] In this embodiment, as the time of the mixed rare earth concentrate undergoing the mineral phase transformation increases, the carbon in the mixed rare earth concentrate reacts to generate carbon dioxide, thereby causing the carbon content in the mixed rare earth concentrate to gradually decrease, while the content of tetravalent cerium ions gradually increases. Therefore, when the mineral phase transformation of the mixed rare earth concentrate is complete, the carbon content in the mixed rare earth concentrate is reduced to 0. Therefore, by monitoring the carbon content in the mixed rare earth concentrate, it can be determined whether the fluorocarbon cerium rare earth in the mixed rare earth concentrate is completely decomposed to complete the mineral phase transformation. It can be seen that this embodiment can determine the mineral phase transformation of the fluorocarbon cerium rare earth by detecting the carbon content in the mixed rare earth concentrate, and stop the mineral phase transformation reaction of the mixed rare earth concentrate when the carbon content in the mixed rare earth concentrate is 0, so that the CeO in the final mixed rare earth concentrate obtained is 0. 2 The content reaches the maximum value.

[0060] In some possible embodiments, the mineral phase conversion product is cooled to 25° C. under air to complete the cooling process of the mineral phase conversion product.

[0061] Here, by introducing air during the cooling process of the mineral phase conversion product, the fluorocarbon cerium rare earth in the mineral phase conversion product can be further oxidized to increase the CeO in the final mixed rare earth concentrate. 2 The content.

[0062] The following is a detailed description of the pretreatment method of a mixed rare earth concentrate provided by the present invention through examples. It should be noted that the methods, reagents and materials described in the following examples, unless otherwise specified, can all be obtained from commercial channels; the test methods, unless otherwise specified, are all conventional methods.

[0063] Example 1

[0064] The present embodiment provides a method for pretreating a mixed rare earth concentrate, comprising the following steps:

[0065] (1) After a mixed rare earth concentrate having a rare earth oxide REO grade of 50% is fed into a mineral phase conversion reactor, air is continuously introduced into the bottom of the mineral phase conversion reactor at a gas flow rate of 400 mL / min, and the air is used as a fluidizing gas to keep the mixed rare earth concentrate in a fluidized state;

[0066] Among them, the mixed rare earth concentrate with a particle size of less than 0.038 mm accounts for at least 96% of the total weight of the mixed rare earth concentrate; the mixed rare earth concentrate includes 2.72 parts of carbon; the REO in the mixed rare earth concentrate includes the following components and their weight proportions are: La 2 O 3 28.15 parts, CeO 2 51.14 copies, Pr 6 O 11 4.79 parts, Nd 2 O 3 13.98 copies, Sm 2 O 3 0.99 parts, Eu 2 O 3 0.18 parts, Gd 2 O 3 0.39 parts.

[0067] (2) The heating temperature of the ore phase conversion reactor is adjusted so that the mixed rare earth concentrate in a fluidized state is heated at 500° C. for 70 minutes to oxidize the trivalent cerium ions in the fluorocarbon cerium rare earth to generate cerium oxide.

[0068] (3) According to the carbon content in the mixed rare earth concentrate, the mineral phase transformation of the fluorocarbon cerium rare earth is determined, and when the carbon content in the mixed rare earth concentrate is 0, the mineral phase transformation reaction of the mixed rare earth concentrate is stopped to complete the oxidation reaction of part of the trivalent cerium ions in the fluorocarbon cerium rare earth into tetravalent cerium ions, thereby obtaining a mineral phase transformation product containing tetravalent cerium ions.

[0069] (4) After the mineral phase transformation product is cooled to 25°C in air, the cooling treatment of the mineral phase transformation product is completed.

[0070] As shown in Table 1, at a roasting temperature of 500°C, the relationship between the carbon content and the tetravalent cerium ion (Ce(IV) content) in the mixed rare earth concentrate and the heating time of fluidized roasting. By analyzing Table 1, it can be seen that as the heating time increases, the carbon in the fluorocarbon cerium rare earth is converted into CO 2 , and then the carbon content in the mixed rare earth concentrate gradually decreased, and the Ce(Ⅳ) content gradually increased. After 70 minutes of heating, the carbon content of the mixed rare earth concentrate dropped to 0, indicating that the fluorocarbon cerium rare earth had been completely decomposed. At this time, the CeO in the mineral phase transformation product obtained was 2 The content reaches the maximum value.

[0071] Table 1 CeO in mineral phase transformation products 2 Relationship between content and heating time

[0072]

[0073] Example 2

[0074] The present embodiment provides a method for pretreating a mixed rare earth concentrate, comprising the following steps:

[0075] (1) After a mixed rare earth concentrate having a rare earth oxide REO grade of 60% is fed into a mineral phase conversion reactor, air is continuously introduced into the bottom of the mineral phase conversion reactor at a gas flow rate of 400 mL / min, and the air is used as a fluidizing gas to keep the mixed rare earth concentrate in a fluidized state;

[0076] Among them, the mixed rare earth concentrate with a particle size of less than 0.038 mm accounts for at least 96% of the total weight of the mixed rare earth concentrate; the mixed rare earth concentrate includes 2.72 parts of carbon; the REO in the mixed rare earth concentrate includes the following components and their weight proportions are: La 2 O 3 28.15 parts, CeO 2 51.14 copies, Pr 6 O 11 4.79 parts, Nd 2 O 3 13.98 copies, Sm 2 O 3 0.99 parts, Eu 2 O 3 0.18 parts, Gd 2 O 3 0.39 parts.

[0077] (2) The heating temperature of the ore phase conversion reactor is adjusted so that the mixed rare earth concentrate in a fluidized state is heated at 550° C. for 40 minutes to oxidize the trivalent cerium ions in the fluorocarbon cerium rare earth to generate cerium oxide.

[0078] (3) According to the carbon content in the mixed rare earth concentrate, the mineral phase transformation of the fluorocarbon cerium rare earth is determined, and when the carbon content in the mixed rare earth concentrate is 0, the mineral phase transformation reaction of the mixed rare earth concentrate is stopped to complete the oxidation reaction of part of the trivalent cerium ions in the fluorocarbon cerium rare earth into tetravalent cerium ions, thereby obtaining a mineral phase transformation product containing tetravalent cerium ions.

[0079] (4) After the mineral phase transformation product is cooled to 25°C in air, the cooling treatment of the mineral phase transformation product is completed.

[0080] As shown in Table 2, at a roasting temperature of 550°C, the relationship between the carbon content and the tetravalent cerium ion (Ce(IV) content) in the mixed rare earth concentrate and the heating time of fluidized roasting. By analyzing Table 2, it can be seen that as the heating time increases, the carbon in the fluorocarbon cerium rare earth is converted into CO 2, and then the carbon content in the mixed rare earth concentrate gradually decreased, and the Ce(Ⅳ) content gradually increased. After 40 minutes of heating, the carbon content of the mixed rare earth concentrate dropped to 0, indicating that the fluorocarbon cerium rare earth had been completely decomposed. At this time, the CeO in the mineral phase transformation product obtained was 2 The content reaches the maximum value.

[0081] Table 2 CeO in mineral phase transformation products 2 Relationship between content and heating time

[0082]

[0083] Example 3

[0084] The present embodiment provides a method for pretreating a mixed rare earth concentrate, comprising the following steps:

[0085] (1) After a mixed rare earth concentrate having a rare earth oxide REO grade of 65% is fed into a mineral phase conversion reactor, air is continuously introduced into the bottom of the mineral phase conversion reactor at a gas flow rate of 400 mL / min, and the air is used as a fluidizing gas to keep the mixed rare earth concentrate in a fluidized state;

[0086] Among them, the mixed rare earth concentrate with a particle size of less than 0.038 mm accounts for at least 96% of the total weight of the mixed rare earth concentrate; the mixed rare earth concentrate includes 2.72 parts of carbon; the REO in the mixed rare earth concentrate includes the following components and their weight proportions are: La 2 O 3 28.15 parts, CeO 2 51.14 copies, Pr 6 O 11 4.79 parts, Nd 2 O 3 13.98 copies, Sm 2 O 3 0.99 parts, Eu 2 O 3 0.18 parts, Gd 2 O 3 0.39 parts.

[0087] (2) The heating temperature of the ore phase conversion reactor is adjusted so that the mixed rare earth concentrate in a fluidized state is heated at 600° C. for 15 minutes to oxidize the trivalent cerium ions in the fluorocarbon cerium rare earth to generate cerium oxide.

[0088] (3) According to the carbon content in the mixed rare earth concentrate, the mineral phase transformation of the fluorocarbon cerium rare earth is determined, and when the carbon content in the mixed rare earth concentrate is 0, the mineral phase transformation reaction of the mixed rare earth concentrate is stopped to complete the oxidation reaction of part of the trivalent cerium ions in the fluorocarbon cerium rare earth into tetravalent cerium ions, thereby obtaining a mineral phase transformation product containing tetravalent cerium ions.

[0089] (4) After the mineral phase transformation product is cooled to 25°C in air, the cooling treatment of the mineral phase transformation product is completed.

[0090] As shown in Table 3, at a roasting temperature of 600°C, the relationship between the carbon content and the tetravalent cerium ion (Ce(IV) content) in the mixed rare earth concentrate and the heating time of fluidized roasting. By analyzing Table 3, it can be seen that as the heating time increases, the carbon in the fluorocarbon cerium rare earth is converted into CO 2 , and then the carbon content in the mixed rare earth concentrate gradually decreased, and the Ce(Ⅳ) content gradually increased. After 15 minutes of heating, the carbon content of the mixed rare earth concentrate dropped to 0, indicating that the fluorocarbon cerium rare earth had been completely decomposed. At this time, the CeO in the mineral phase transformation product obtained was 2 The content reaches the maximum value.

[0091] Table 3 CeO in mineral phase transformation products 2 Relationship between content and heating time

[0092]

[0093] Example 4

[0094] The present embodiment provides a method for pretreating a mixed rare earth concentrate, comprising the following steps:

[0095] (1) After a mixed rare earth concentrate having a rare earth oxide REO grade of 59% is fed into a mineral phase conversion reactor, air is continuously introduced into the bottom of the mineral phase conversion reactor at a gas flow rate of 400 mL / min, and the air is used as a fluidizing gas to keep the mixed rare earth concentrate in a fluidized state;

[0096] Among them, the mixed rare earth concentrate with a particle size of less than 0.038 mm accounts for at least 96% of the total weight of the mixed rare earth concentrate; the mixed rare earth concentrate includes 2.72 parts of carbon; the REO in the mixed rare earth concentrate includes the following components and their weight proportions are: La 2 O 3 28.15 parts, CeO 2 51.14 copies, Pr 6 O 11 4.79 parts, Nd 2 O 3 13.98 copies, Sm 2 O 30.99 parts, Eu 2 O 3 0.18 parts, Gd 2 O 3 0.39 parts.

[0097] (2) The heating temperature of the ore phase conversion reactor is adjusted so that the mixed rare earth concentrate in a fluidized state is heated at 650° C. for 10 min to oxidize the trivalent cerium ions in the fluorocarbon cerium rare earth to generate cerium oxide.

[0098] (3) According to the carbon content in the mixed rare earth concentrate, the mineral phase transformation of the fluorocarbon cerium rare earth is determined, and when the carbon content in the mixed rare earth concentrate is 0, the mineral phase transformation reaction of the mixed rare earth concentrate is stopped to complete the oxidation reaction of part of the trivalent cerium ions in the fluorocarbon cerium rare earth into tetravalent cerium ions, thereby obtaining a mineral phase transformation product containing tetravalent cerium ions.

[0099] (4) After the mineral phase transformation product is cooled to 25°C in air, the cooling treatment of the mineral phase transformation product is completed.

[0100] As shown in Table 4, at a roasting temperature of 650°C, the relationship between the carbon content and the tetravalent cerium ion (Ce(IV) content) in the mixed rare earth concentrate and the heating time of fluidized roasting. By analyzing Table 4, it can be seen that as the heating time increases, the carbon in the fluorocarbon cerium rare earth is converted into CO 2 , and then the carbon content in the mixed rare earth concentrate gradually decreased, and the Ce(Ⅳ) content gradually increased. After 10 minutes of heating, the carbon content of the mixed rare earth concentrate dropped to 0, indicating that the fluorocarbon cerium rare earth had been completely decomposed. At this time, the CeO in the mineral phase conversion product obtained was 2 The content reaches the maximum value.

[0101] Table 4 CeO in mineral phase transformation products 2 Relationship between content and heating time

[0102]

[0103] Example 5

[0104] The present embodiment provides a method for pretreating a mixed rare earth concentrate, comprising the following steps:

[0105] (1) After a mixed rare earth concentrate having a rare earth oxide REO grade of 63% is fed into a mineral phase conversion reactor, air is continuously introduced into the bottom of the mineral phase conversion reactor at a gas flow rate of 400 mL / min, and the air is used as a fluidizing gas to keep the mixed rare earth concentrate in a fluidized state;

[0106] Among them, the mixed rare earth concentrate with a particle size of less than 0.038 mm accounts for at least 96% of the total weight of the mixed rare earth concentrate; the mixed rare earth concentrate includes 2.72 parts of carbon; the REO in the mixed rare earth concentrate includes the following components and their weight proportions are: La 2 O 3 28.15 parts, CeO 2 51.14 copies, Pr 6 O 11 4.79 parts, Nd 2 O 3 13.98 copies, Sm 2 O 3 0.99 parts, Eu 2 O 3 0.18 parts, Gd 2 O 3 0.39 parts.

[0107] (2) The heating temperature of the ore phase conversion reactor is adjusted so that the mixed rare earth concentrate in a fluidized state is heated at 700° C. for 7 minutes to oxidize the trivalent cerium ions in the fluorocarbon cerium rare earth to generate cerium oxide.

[0108] (3) According to the carbon content in the mixed rare earth concentrate, the mineral phase transformation of the fluorocarbon cerium rare earth is determined, and when the carbon content in the mixed rare earth concentrate is 0, the mineral phase transformation reaction of the mixed rare earth concentrate is stopped to complete the oxidation reaction of part of the trivalent cerium ions in the fluorocarbon cerium rare earth into tetravalent cerium ions, thereby obtaining a mineral phase transformation product containing tetravalent cerium ions.

[0109] (4) After the mineral phase transformation product is cooled to 25°C in air, the cooling treatment of the mineral phase transformation product is completed.

[0110] As shown in Table 5, at a roasting temperature of 700°C, the relationship between the carbon content and the tetravalent cerium ion (Ce(IV) content) in the mixed rare earth concentrate and the heating time of fluidized roasting. By analyzing Table 5, it can be seen that as the heating time increases, the carbon in the fluorocarbon cerium rare earth is converted into CO 2 , and then the carbon content in the mixed rare earth concentrate gradually decreased, and the Ce(Ⅳ) content gradually increased. After 7 minutes of heating, the carbon content of the mixed rare earth concentrate dropped to 0, indicating that the fluorocarbon cerium rare earth had been completely decomposed. At this time, the CeO in the mineral phase transformation product obtained was 2 The content reaches the maximum value.

[0111] Table 5 CeO in mineral phase transformation products 2 Relationship between content and heating time

[0112]

[0113] Comparative Example 1

[0114] Relative to Example 2, the pretreatment method of a mixed rare earth concentrate provided in this embodiment is basically the same as the preparation method provided in Example 2, with the difference being that the air involved in step 1 and step 4 is replaced with nitrogen, that is, the mixed rare earth concentrate is fluidized roasted using nitrogen as the fluidizing gas, and the mineral phase conversion product is cooled in a nitrogen atmosphere, and the other steps and the process parameters involved remain unchanged.

[0115] As shown in Table 6, the relationship between the carbon content and Ce(IV) content in the mixed rare earth concentrate and the heating time at a roasting temperature of 550°C. It can be seen that with the extension of the heating time, the carbon content gradually decreases, and the Ce(IV) content is always 0. This indicates that there is no CeO in the sample after fluidized roasting in a nitrogen atmosphere. 2 Generation of.

[0116] Table 6 CeO in mineral phase transformation products 2 Relationship between content and heating time

[0117]

[0118] It can be seen from the above-mentioned embodiments and comparative examples that the pretreatment method of the mixed rare earth concentrate adopted by the present invention uses air as the fluidizing gas to oxidize the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate to generate cerium oxide, while in Comparative Example 1, nitrogen is used as the fluidizing gas, but the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate cannot be oxidized. It can be seen that the present invention can provide a basis for achieving effective separation of cerium rare earth and non-cerium rare earth, thereby improving the recovery rate of high-value non-cerium trivalent rare earth.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for pretreating a mixed rare earth concentrate, characterized in that: include: The mixed rare earth concentrate is subjected to ore phase transformation, so that part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate is oxidized into tetravalent cerium ions, and an ore phase transformation product containing tetravalent cerium ions is obtained; wherein the mixed rare earth concentrate with a particle size of less than 0.038 mm accounts for at least 96% of the total weight of the mixed rare earth concentrate; and the mixed rare earth concentrate contains 2.72 parts of carbon element; Cooling the mineral phase conversion product under air to complete the pretreatment of the mixed rare earth concentrate; The mixed rare earth concentrate is subjected to ore phase transformation to oxidize part of the trivalent cerium ions in the fluorocarbon cerium rare earth in the mixed rare earth concentrate into tetravalent cerium ions to obtain an ore phase transformation product containing tetravalent cerium ions, including: After the mixed rare earth concentrate is fed into the ore phase conversion reactor, air is continuously introduced into the bottom of the ore phase conversion reactor, and the air is used as a fluidizing gas to keep the mixed rare earth concentrate in a fluidized state; the gas flow rate of the air introduced into the bottom of the ore phase conversion reactor is 400-500 mL / min; The heating temperature of the mineral phase conversion reactor is adjusted so that the mixed rare earth concentrate in a fluidized state is heated at a temperature of 650-700°C for 7-10 minutes to oxidize the trivalent cerium ions in the fluorocarbon cerium rare earth to generate cerium oxide, thereby completing the oxidation reaction of converting part of the trivalent cerium ions in the fluorocarbon cerium rare earth into tetravalent cerium ions; wherein, the mineral phase conversion of the fluorocarbon cerium rare earth is judged according to the carbon content in the mixed rare earth concentrate, and the mineral phase conversion reaction of the mixed rare earth concentrate is stopped when the carbon content in the mixed rare earth concentrate is 0.

2. The pretreatment method of mixed rare earth concentrate according to claim 1, characterized in that: The rare earth oxide REO grade in the mixed rare earth concentrate is 50% to 65%, wherein RE includes Ce, La, Pr, Nd, Sm, Eu and Gd.

3. The pretreatment method of mixed rare earth concentrate according to claim 2, characterized in that: The REO in the mixed rare earth concentrate includes the following components and their weight proportions are: La2O3 28.15 parts, CeO2 51.14 parts, Pr6O 11 4.79 parts, Nd2O313.98 parts, Sm2O30.99 parts, Eu2O30.18 parts, Gd2O30.39 parts.

4. The pretreatment method of the mixed rare earth concentrate according to any one of claims 1 to 3, characterized in that: After the mineral phase conversion product is cooled to 25° C. under air, the cooling treatment of the mineral phase conversion product is completed.

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