Method and equipment for melting, separating and extracting iron and rare earth in rare earth iron ore

Abstract

The invention discloses a method and equipment for melting, separating and extracting iron and rare earth in rare earth iron ore. The method comprises the following steps: obtaining a molten material of rare earth iron ore and reducing agent powder at 1200-1500 DEG C; the molten material is subjected to centrifugal treatment through a centrifugal separation solidification machine, the molten material is gradually cooled and solidified in the centrifugal treatment process, four coagulum layers are formed, the four coagulum layers are cut and separated, and iron and rare earth enriched substances are obtained; and the rare earth enrichment is subjected to hydrochloric acid leaching and oxalic acid or carbonate precipitation process treatment, and then mixed rare earth precipitation is obtained. According to the method, the iron recovery rate can reach 99%, the grade of a rare earth enriched product can reach 59% or above, the rare earth recovery rate can reach 80% or above, the separation efficiency is high, the iron and rare earth recovery rates are high, the technological process is short, the method is environmentally friendly, equipment is simple, and the cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of rare earth iron ore extraction methods, and particularly relates to a method and device for extracting iron and rare earth from rare earth iron ore through melting separation. Background Art

[0002] The Bayan Obo deposit is a super-large rare earth iron ore with symbiotic iron, niobium and rare earth metals. There are more than 210 kinds of minerals, and 15 kinds of rare earth minerals. The minerals are closely intergrown and the symbiotic relationship is complex. Under the current beneficiation and smelting conditions, the utilization rate of rare earth resources is only 10%-15%. A large amount of rare earth-containing tailings are discharged into the tailings dam, resulting in resource waste.

[0003] In recent years, through the optimization of the combined process of flotation, gravity separation and magnetic separation, generally, the rare earth recovery rate can be increased to 51.66-57.34%. However, 80% of the mixed rare earth concentrates are smelted by the sulfuric acid method. The rare earth concentrate is mixed and roasted with concentrated sulfuric acid to generate rare earth sulfate, and then the rare earth is extracted by water leaching. The smelting process will generate sulfur-containing waste gas, polluting the environment, and will also generate insoluble pyrophosphate formed by radioactive thorium elements, which requires an additional treatment process.

[0004] And some other extraction methods with higher recovery rates also face many problems. For example, the prior art CN201310416337 uses the supergravity technology to separate rare earth from rare earth slag. After the molten rare earth slag is slowly cooled to 1300-1150°C and then centrifugally separated, the rare earth recovery rate reaches 85%-90%. However, it has the following problems: it is necessary to add CaO or SiO 2 to adjust the alkalinity, reduce the rare earth concentration, and increase the cost; the cooling and rewarming steps are complex and the efficiency is low; the equipment is complex, high-temperature operation is required, the energy consumption is high, and the maintenance cost is high. The prior art CN113930630A uses the supergravity cascade to separate different rare earth elements in rare earth concentrate, and realizes the separation of Ce, La, Pr, and Nd through melting-cooling-centrifugation. However, it has the following problems: it is only applicable to rare earth concentrate and does not improve the utilization rate of rare earth resources; the process is long and the energy consumption is high; the equipment is complex and the service life of moving parts is short in a high-temperature environment. The prior art CN106148736B uses low-temperature separation of rare earth ore, reduces iron, slag and rare earth phases in the reduced ore, and realizes the separation of the iron phase and the slag phase through centrifugal treatment. However, the obtained rare earth phase is still enriched in the slag phase, and the efficient separation of rare earth and slag is not achieved, and the equipment has high requirements for high temperature resistance and high operation cost.

[0005] In summary, the following problems exist in the prior art: low rare earth recovery rate: the recovery rate of physical separation is difficult to exceed 80%, and the recovery rate of smelting process is limited; complex process: multiple steps of operation are required, with low efficiency and high energy consumption; poor environmental protection: sulfur-containing waste gas is generated during the smelting process, and the radioactive thorium element needs special disposal; high equipment cost: high-temperature operation and complex equipment lead to high energy consumption and maintenance cost. Therefore, there is still an urgent need to develop a method for separating and extracting rare earths from rare earth iron ores and their tailings such as Bayan Obo ore, which has a high rare earth recovery rate, a short process flow, is green and environmentally friendly, has simple equipment and low cost. Summary of the Invention

[0006] To solve the problems of the prior art, the object of the present invention is to provide a method and equipment for separating and extracting rare earth iron ores / tailings with a high rare earth recovery rate, a short process flow, being green and environmentally friendly, having simple equipment and low cost.

[0007] The technical solution of the present invention is as follows:

[0008] A method for melting and separating to extract iron and rare earths from rare earth iron ores, comprising:

[0009] (1) Mix the rare earth iron ore evenly with the reducing agent powder to obtain a mixed material, and perform melting reduction treatment on the mixed material at 1200 - 1500 °C for 0.5 - 4 h to obtain a molten material; wherein, the reducing agent contains elemental carbon; the mass of the reducing agent powder is 3 - 10% of the mass of the rare earth iron ore;

[0010] (2) Centrifuge the molten material at a centrifuge speed of 500 - 4000 r / min and let it gradually cool and solidify during the centrifugation process to form a hollow cylinder with a total of four solidified layer layers from the inside to the outside; the four solidified layer layers are concentrically distributed in a ring shape, and are successively layer A, layer B, layer C and layer D from the inside to the outside; the centrifugation time is 5 - 40 min;

[0011] (3) Cut and separate the four solidified layer layers to obtain layer A, i.e., a solidified material layer rich in calcium fluoride and zero rare earths, layer B, i.e., a solidified material layer rich in calcium fluoride and poor in rare earths, layer C, i.e., a solidified material layer rich in rare earths, and layer D, i.e., a solidified material layer of metallic iron;

[0012] (4) Use the obtained solidified material layer B as return material, that is, when performing the next melting and separating to extract iron and rare earths from rare earth iron ores, add the obtained solidified material layer B to the mixed material in step (1), and then perform steps (2) - (3); wherein, the addition amount of the solidified material layer B accounts for 1 - 50% of the total mass of the mixed material;

[0013] (5) Grind the obtained C-layer solidified product to obtain rare earth-rich powder with a particle size less than 45 μm. Add the rare earth-rich powder to hydrochloric acid with a concentration of 6-12 mol / L, and carry out leaching treatment at 25-100 °C for 10-180 min. Then, separate the leaching solution and the leaching residue. The obtained leaching solution is a rare earth chloride leaching solution, and store the leaching residue;

[0014] (6) Add a precipitant solution to the rare earth chloride leaching solution to obtain a mixed solution. Carry out a precipitation reaction on the mixed solution at 20-100 °C, and then separate the precipitate to obtain a mixed rare earth precipitate; the precipitant is selected from oxalic acid and / or carbonate.

[0015] Preferably, the precipitant is oxalic acid; the pH of the mixed solution is 1-3. Among them, the molar ratio of oxalic acid to rare earth chloride is 0.5-3:1, and the concentration of rare earth chloride is 1-10 g / L; and the method further includes: calcining the mixed rare earth precipitate at 800-1000 °C for 1-3 h to obtain a mixed rare earth oxide.

[0016] More preferably, the precipitant is oxalic acid, the temperature of the precipitation reaction is 40-60 °C, the pH of the mixed solution is 1.5, the concentration of rare earth chloride is 1-5 g / L, and the molar ratio of oxalic acid to rare earth chloride is 1.5-2:1.

[0017] More preferably, the calcining temperature is 950 °C and the calcining time is 1-2 h.

[0018] Preferably, the precipitant is carbonate; the pH of the mixed solution is 4-6. Among them, the molar ratio of carbonate to rare earth chloride is 0.5-5:1, and the temperature of the precipitation reaction is 25-100 °C.

[0019] More preferably, the precipitant is carbonate, the temperature of the precipitation reaction is 25-40 °C; the pH of the mixed solution is 4.5, and the molar ratio of carbonate to rare earth chloride is 1.5-2:1.

[0020] Preferably, the carbonate is selected from one or more of sodium carbonate, sodium bicarbonate, ammonium bicarbonate, and magnesium bicarbonate.

[0021] Preferably, the reducing agent powder is selected from one or more of pulverized coal, graphite powder, carbon powder, and coke powder.

[0022] Preferably, the mass of the reducing agent powder is 4-7% of the mass of the rare earth iron ore.

[0023] Preferably, in step (4), the mass of the B-layer solidified product added each time is 1-50% of the mass of the mixed material, and more preferably, it is 10-20%.

[0024] Preferably, in step (5), the leaching treatment is carried out under stirring, and the stirring rate is 300 - 1600 r / min; more preferably, it is 500 - 800 r / min.

[0025] Preferably, in step (5), the solid-liquid ratio of the leaching system obtained by adding the rare-earth-rich powder to hydrochloric acid with a concentration of 6 - 12 mol / L is 1 - 30 mg / L.

[0026] Preferably, in step (1), the heat preservation temperature for the smelting reduction treatment is 1250 - 1400 °C, and the heat preservation time is 0.5 - 2 h.

[0027] Preferably, in step (2), the centrifugation rate is 2000 - 3000 r / min, and the centrifugation time is 10 - 30 min.

[0028] Preferably, in step (5), the temperature for the leaching treatment is 40 - 50 °C, the solid-liquid ratio is 15 - 25 mg / L, the hydrochloric acid concentration is 6 mol / L, and the leaching time is 60 - 90 min.

[0029] Preferably, in the cutting separation, the cutting thickness of the solidified matter in layer A is 10 - 40% of the overall thickness of the hollow cylinder, the cutting thickness of the solidified matter in layer B is 10 - 40% of the overall thickness of the hollow cylinder, the cutting thickness of the solidified matter in layer C is 10 - 30% of the overall thickness of the hollow cylinder, and the cutting thickness of the solidified matter in layer D is 1 - 20% of the overall thickness of the hollow cylinder.

[0030] The present invention further provides a device for implementing the above method, which includes: a high-temperature furnace for subjecting the mixed material to smelting reduction treatment; a centrifugal separation and solidification machine for centrifuging the molten material and cooling and solidifying it during the centrifuging process to form a solidified material layer distributed in four concentric circular rings; a cutting separation device for cutting and separating the solidified material layer generated by the centrifugal separation and solidification machine; wherein, the centrifugal separation and solidification machine includes an electric motor for providing power, a centrifugal separation and solidification machine main body connected to the electric motor through a transmission rod, a front cover of the centrifugal separation and solidification machine located at the front end of the centrifugal separation and solidification machine main body that can be opened and closed, an equipment base for stably supporting the centrifugal separation and solidification machine main body, a slag chute for introducing the molten material into the centrifugal separation and solidification machine main body, and an orbital moving platform provided with internal gears for adjusting the horizontal position of the slag chute; wherein, the centrifugal separation and solidification machine main body is a centrifugal rotating machine provided with an internal cavity; the cavity wall of the internal cavity of the centrifugal separation and solidification machine main body and the surface of the trough body of the slag chute are both formed of a composite layer material, and the composite layer material includes a steel material outer shell, an alumina refractory and heat-insulating material layer located inside the steel material outer shell for fire resistance and heat insulation, and a high-purity graphite layer located inside the alumina refractory and heat-insulating material layer for forming the solidified material; the cutting separation device includes a cutting tool head that can extend into the internal cavity of the centrifugal separation and solidification machine main body, a tool head driving motor connected to the cutting tool head through a shock-resistant tool rod, and a hydraulic hoist for controlling the up and down movement of the tool head driving motor through a hydraulic pipe.

[0031] Preferably, the centrifugal separation and solidification machine main body is provided with a heat dissipation outer shell, and the heat dissipation outer shell is evenly distributed with heat dissipation fins.

[0032] Preferably, the equipment base is provided with support guide rails and support pulleys that can slide horizontally on the support guide rails, and the centrifugal separation and solidification machine main body is arranged on the support guide rails through the support pulleys.

[0033] Preferably, the cutting tool head is distributed with spiral cutting edges, and there are two cutting edges at the front end of the tool head. During the cutting operation, the cutting tool head can rotate self-rotationally and move up and down following the tool head driving motor.

[0034] Preferably, the slag chute and the cutting separation device can be alternatively placed on the orbital moving platform to add the molten material or cut and separate the solidified material as needed.

[0035] The present invention has the following beneficial effects:

[0036] (1) The present invention can directly treat the Bayan Obo original ore or iron ore dressing tailings without adding additional additives and without changing the elemental composition of the minerals.

[0037] (2) The main phase components of the calcium fluoride-rich and rare-earth-free powder obtained by recycling in the present invention are calcium fluoride, calcium silicate, and cuspidine, which is a good raw material for continuous casting powder or smelting additive; the main components of the leaching residue are calcium fluoride and silicon dioxide, which can be used as smelting additives or as additives in the smelting reduction process;

[0038] (3) In the method of the present invention, the calcium fluoride-rich and rare-earth-poor powder can be recycled, without the need to purchase other additives additionally, saving costs; the rare earth in the calcium fluoride-rich and rare-earth-poor layer can be further recovered to improve the rare earth recovery rate; the calcium fluoride concentration in the formed recycled material is high, which can control the proportion of calcium fluoride in the slag, reduce the overall melting point of the slag, and enhance the melting aggregation of metallic iron and the centrifugal enrichment effect of the rare earth phase;

[0039] (4) The mass fraction of iron in the slag phase obtained in the present invention is less than 0.09%, and the recovery rate of iron is as high as over 99%, realizing the complete separation of iron; the rare earth grade of the rare earth-rich layer can reach 59.21%, and the single-time melting separation recovery rate of rare earth can reach 81.32%; in the preferred embodiment, the leaching rate of rare earth can reach over 99%, the precipitation rate can reach over 99%, and the open-circuit single-time comprehensive rare earth recovery rate can reach over 79.7%;

[0040] (5) The process flow of the present invention is short, the production cost is low, and there is no waste gas or waste residue discharge, which is an environmentally friendly and efficient separation and recovery method;

[0041] (6) The rare earth extraction product obtained in the present invention is mixed rare earth oxide or mixed rare earth carbonate precipitate, which can be directly dissolved in inorganic acid and then flexibly used in the rare earth extraction process, with strong process adaptability;

[0042] (7) The process of the present invention has no waste gas or waste residue discharge, which is a process method in the field of environmentally friendly comprehensive resource recovery and utilization;

[0043] (8) The equipment of the present invention has a simple structure, is easy to maintain, covers a small area, and has a low investment cost; its use method is simple, and continuous production can be realized by parallel operation of multiple devices, with high processing efficiency; at the same time, the separation operation of the equipment is carried out at room temperature, without a heating system and a material receiving device, with low energy consumption and a long service life. Brief Description of the Drawings

[0044] Figure 1 It is a schematic diagram of the overall structure of the centrifugal separation and solidification machine in Example 1.

[0045] Figure 2 It is a schematic diagram of the external structure of the main body and the equipment base of the centrifugal separation and solidification machine in Example 1.

[0046] Figure 3 It is a schematic diagram of the overall structure of the cutting separation device in Example 1.

[0047] Figure 4 It is a schematic flow chart of the method for separating and extracting iron and rare earth from rare earth iron ore by melting in Examples 2-4.

[0048] Figure 5 It is a distribution map of the solidified layer of the slag obtained in Example 2. Detailed implementation manners

[0049] The present invention will be described in detail below in conjunction with the embodiments and the drawings. However, it should be understood that the embodiments and the drawings are only used for exemplary description of the present invention, and do not constitute any limitation to the protection scope of the present invention. All reasonable transformations and combinations within the scope of the inventive concept of the present invention fall within the protection scope of the present invention.

[0050] The methods or operations used in the following embodiments, unless otherwise specified, are all conventional methods or conventional operations in the art.

[0051] Example 1

[0052] Referring to the attached Figures 1 - 3 , the present invention provides an equipment system for separating and extracting iron and rare earth from rare earth iron ore by melting, which includes: a high-temperature furnace for subjecting a mixture of rare earth iron ore and a reducing agent such as pulverized coal, carbon powder, coke powder, and graphite powder to high-temperature melting reduction treatment to obtain a molten material; a centrifugal separation and solidification machine for centrifuging the molten material and cooling and solidifying the layered molten material during centrifugation, and a cutting separation device for cutting and separating the hollow cylindrical solidified product generated by the centrifugal separation and solidification machine.

[0053] Furthermore, the high-temperature furnace can place the mixture and the molten material through a graphite container.

[0054] Furthermore, referring to the attached Figure 1 , the centrifugal separation and solidification machine includes a motor 1 providing power, a centrifugal separation and solidification machine main body 3 connected to the motor 1 through a transmission rod 2, which realizes separation and solidification of different phases according to density by centrifugal force, a centrifugal separation and solidification machine front cover 4 that can be opened and closed at the front end of the centrifugal separation and solidification machine main body 3, an equipment base for stably supporting the centrifugal separation and solidification machine main body 3, a slag chute 7 for introducing the molten material into the centrifugal separation and solidification machine main body 3, and an orbital moving platform 8 provided with internal gears for adjusting the horizontal position of the slag chute 7; wherein, the centrifugal separation and solidification machine main body 3 is a centrifugal rotating machine provided with an internal cavity; the cavity wall of the internal cavity of the centrifugal separation and solidification machine main body 3 and the surface of the trough body of the slag chute 7 are both formed by a composite layer material, and the composite layer material includes a steel material outer shell, an alumina refractory and heat-insulating material layer 5 located inside the steel material outer shell for fireproofing and heat insulation, and a high-purity graphite layer 6 located inside the alumina refractory and heat-insulating material layer for solidifying the molten material separated by centrifugation.

[0055] Preferably, referring to the attached Figure 2 , the centrifugal separation and solidification machine main body 3 is provided with a heat dissipation housing, and the heat dissipation housing is evenly distributed with heat dissipation fins 15.

[0056] Preferably, referring to the attached Figure 2 , a support guide rail 14 and a support pulley 16 that can slide horizontally on the support guide rail 14 are provided on the equipment base 17, and the centrifugal separation and solidification machine main body 3 is arranged on the support guide rail 14 through the support pulley 16 so that it runs stably and can dissipate heat effectively.

[0057] Furthermore, referring to the attached Figure 3 , the cutting and separation device includes a cutting tool head 9 that can extend into the inner cavity of the centrifugal separation and solidification machine main body 3, a tool head driving motor 11 connected to the cutting tool head 9 through a shock-resistant tool rod 10, and a hydraulic hoist 12 that controls the up and down movement of the tool head driving motor 11 through a hydraulic pipe 13.

[0058] Preferably, spiral cutting edges are distributed on the cutting tool head 9, and there are two cutting edges at the front end of the tool head for cutting solidified materials. During the cutting operation, with the centrifugal separation and solidification machine main body 3 rotating, the cutting tool head 9 rotates and moves up and down to complete the cutting work.

[0059] Preferably, the slag chute 7 and the cutting and separation device are replaceably placed on the track moving platform 8 to add molten materials or cut and separate solidified substances as needed.

[0060] Combining the attached Figures 1 - 3 , the operation mode of this equipment system is as follows: Mix rare earth iron ore and pulverized coal evenly, put them into a high-temperature furnace, heat to a predetermined temperature and keep warm to obtain molten materials; start the motor 1, drive the centrifugal separation and solidification machine main body 3 to rotate through the transmission rod 2. When the centrifugal separation and solidification machine main body 3 reaches the established rotation speed, introduce the high-temperature molten materials into the centrifugal separation and solidification machine main body 3 through the slag chute 7. Under the action of centrifugal force, the molten materials solidify on the high-purity graphite layer 6 of the centrifugal separation and solidification machine main body 3 in order of density from large to small, forming four layers of solidified substances, including layer A: calcium fluoride-rich zero-rare earth layer, layer B: calcium fluoride-rich poor-rare earth layer, layer C: rare earth-rich layer, and layer D: metallic iron layer; after the centrifugal solidification is completed, open the front cover 4 of the centrifugal separation and solidification machine, the centrifugal separation and solidification machine main body 3 rotates slowly, the hydraulic hoist 12 controls the cutting tool head 9 to a predetermined height through the tool head driving motor 11, the cutting tool head 9 rotates and moves up and down to cut the four layers of solidified substances respectively, and collect the powdered materials of each layer after cutting, then the efficient separation of iron and rare earth can be achieved.

[0061] Example 2

[0062] The method for separating and extracting iron and rare earth from rare earth iron ore by melting separation of the present invention is used to separate and extract the Bayan Obo iron ore dressing tailings containing mixed rare earths, that is, the tailings described below. The chemical composition of the used tailings is shown in Table 1.

[0063] Table 1 Chemical composition of the Bayan Obo tailings used in Example 1 (mass fraction / %)

[0064] TFe FeO REO <![CDATA[Nb 2 O 5 > CaO <![CDATA[SiO 2 > BaO MgO 13.06 2.10 7.09 0.103 30.34 11.71 4.13 3.32 <![CDATA[Al 2 O 3 > MnO TiO2 F S P <![CDATA[Sodium 2 O]]> <![CDATA[K 2 O]]> 1.39 1.15 0.64 12.50 1.66 1.39 1.03 0.52

[0065] Refer to the appendix Figure 4 , and the separation and extraction steps include:

[0066] (1) Mix the used tailings evenly with graphite powder having a fixed carbon content of 99% and 5wt%, to obtain a mixed material;

[0067] (2) Load 32 g of the mixed material into a graphite crucible, heat it to 1400 °C in a high-temperature furnace and hold for 2 hours to ensure that the mixed material is completely melted and fully reduced;

[0068] (3) Take out the graphite crucible and place it in a centrifuge for centrifugal solidification. During centrifugation, the high-temperature melt will gradually cool and solidify. The rotation speed of the centrifuge is 2500 r / min and the centrifugation time is 5 min; after centrifugal solidification, four solidified layers A, B, C, and D are formed in the centrifuge, as Figure 5 shown. After testing, the iron content in layers A, B, and C is less than 0.1%, and the mass fraction of rare earth oxides in layer C is 59.21%;

[0069] (4) Take 3.13 g of the powder of the solidified material in layer B, that is, the layer rich in calcium fluoride and poor in rare earth, and add it to the graphite crucible together with 25.74 g of the mixed material, and repeat the operations in steps (2)-(3);

[0070] (5) Take the solidified material in layer C, that is, the layer rich in rare earth, grind it to a particle size of <45 μm, weigh 3.28 g, add it to hydrochloric acid with a concentration of 6 mol / L according to the solid-liquid ratio of 15 mg / L, and leach it at 50 °C and a stirring speed of 800 r / min for 60 min. Then, filter it to obtain a rare earth chloride leaching solution and a leaching residue rich in calcium fluoride. Dry the leaching residue and store it;

[0071] (6) Add an oxalic acid solution to the rare earth chloride leaching solution obtained in step (5) to obtain a mixed solution with a pH of 1.5. In the mixed solution, the molar ratio of oxalic acid to rare earth chloride is 2:1, and the mass concentration of rare earth chloride is 3 g / L. Precipitate the obtained mixed solution at 40 °C, and then filter it to obtain a mixed rare earth oxalate precipitate;

[0072] (7) Roast the mixed rare earth oxalate precipitate at 950 °C for 2 hours to obtain a mixed rare earth oxide.

[0073] After calculation, the separation recovery rate of rare earth in this embodiment is 81.32%.

[0074] Example 3

[0075] The tailings of Example 2 were separated and extracted using the equipment system of Example 1 according to the steps Figure 4 shown below. The process is as follows:

[0076] (1) The tailings used were mixed evenly with carbon powder having a fixed carbon content of 99% at 5 wt%, obtaining a mixed material;

[0077] (2) 100 kg of the mixed material was loaded into a graphite container and subjected to melting reduction treatment in a high-temperature furnace. During the reduction treatment, the temperature was raised to 1400 °C and held for 2 hours;

[0078] (3) The centrifugal separation and solidification machine was started, and the rotation speed of the main body of the centrifugal separation and solidification machine was set at 2000 r / min. After the rotation speed reached, the graphite container at 1400 °C was taken out, and the molten material therein was poured into the main body of the centrifugal separation and solidification machine through a slag chute, and processed for 30 min at the set rotation speed, obtaining four solidified layer substances A, B, C, and D;

[0079] (4) The four solidified layer substances A, B, C, and D were separated by a cutting separation device;

[0080] (5) 10 kg of the powder of the solidified substance of layer B, i.e., the layer rich in calcium fluoride and poor in rare earth, was taken and added to a graphite container together with 90 kg of the mixed material, and the operations of steps (2)-(3) were repeated;

[0081] (6) The solidified substance of layer C, i.e., the layer rich in rare earth, was taken, ground to a particle size of <45 μm, weighed 8.7 kg, and added to hydrochloric acid with a concentration of 7 mol / L in an amount according to a solid-liquid ratio of 20 mg / L, and leached for 60 min at a stirring speed of 60 °C and 800 r / min. Thereafter, a rare earth chloride leaching solution and a leaching residue rich in calcium fluoride were obtained by suction filtration, and the leaching residue was dried and stored;

[0082] (7) An oxalic acid solution was added to the rare earth chloride leaching solution obtained in step (6) to obtain a mixed solution with a pH of 1.5. In the mixed solution, the molar ratio of oxalic acid to rare earth chloride was 2:1, and the mass concentration of rare earth chloride was 5 g / L. The obtained mixed solution was precipitated at 40 °C, and then a mixed rare earth oxalate precipitate was obtained by suction filtration;

[0083] (8) The mixed rare earth oxalate precipitate was calcined at 950 °C for 2 hours to obtain a mixed rare earth oxide.

[0084] After calculation, the separation recovery rate of rare earth in this embodiment is 78.48%.

[0085] Example 4

[0086] The tailings of Example 2 were separated and extracted using the equipment system of Example 1 according to the steps Figure 4 shown as follows:

[0087] (1) 15 kg of the powder of the solidified product of layer B, i.e., the calcium fluoride-rich and rare earth-poor layer, obtained in step (5) of Example 3, and 85 kg of the mixed material obtained in step (1) thereof were added into a graphite container and subjected to molten reduction treatment in a high-temperature furnace. During the reduction treatment, the temperature was raised to 1400 °C and held for 2 hours;

[0088] (2) Start the centrifugal separation solidifier, set the rotation speed of the main body of the centrifugal separation solidifier to 2000 r / min. After the rotation speed reached, take out the graphite container, pour the molten material therein into the main body of the centrifugal separation solidifier through the slag chute, and process for 30 min at the set rotation speed to obtain four solidified layers A, B, C, and D;

[0089] (3) Cut and separate the four solidified layers A, B, C, and D through the cutting separation device;

[0090] (4) Take the solidified product of layer C, i.e., the rare earth-rich layer, grind it to a particle size of <45 μm, weigh the mass to be 10.9 kg, add it to hydrochloric acid with a concentration of 10 mol / L according to the solid-liquid ratio of 10 mg / L, and leach for 60 min at 60 °C and a stirring speed of 800 r / min. Then, filter by suction to obtain a rare earth chloride leaching solution and a leaching residue rich in calcium fluoride, and dry the leaching residue and store it;

[0091] (5) Add a sodium carbonate solution to the rare earth chloride leaching solution obtained in step (4) to obtain a mixed solution with a pH of 5. In the mixed solution, the molar ratio of sodium carbonate to rare earth chloride is 2:1, and the concentration of sodium carbonate is 0.5 mol / L. Precipitate the obtained mixed solution at 40 °C, and then filter by suction to obtain a mixed rare earth carbonate precipitate. The obtained precipitate does not require subsequent treatment. After calculation, the separation recovery rate of rare earths in this example is 81.71%.

[0092] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for extracting iron and rare earth from rare earth iron ore by melting separation, characterized in that: It includes: (1) mixing rare earth iron ore and reducing agent powder uniformly to obtain a mixed material, and subjecting the mixed material to a molten reduction treatment at 1200-1500° C. for 0.5-4 h to obtain a molten material; wherein the reducing agent contains a single carbon substance; and the mass of the reducing agent powder is 3-10% of the mass of the rare earth iron ore; (2) centrifuging the molten material at a centrifugal speed of 500-4000 r / min and allowing the molten material to gradually cool down and solidify during the centrifugal treatment to form a hollow cylinder with four solidified material layers from the inside to the outside; the four solidified material layers are distributed in concentric rings, and are layer A, layer B, layer C and layer D from the inside to the outside; the centrifugal treatment time is 5-40 min; (3) cutting and separating the four solidified layers to obtain layer A, i.e., a calcium fluoride-rich and rare earth-free solidified layer, layer B, i.e., a calcium fluoride-rich and rare earth-poor solidified layer, layer C, i.e., a rare earth-rich solidified layer, and layer D, i.e., a metallic iron solidified layer; (4) using the obtained B-layer solidified material as a return material, i.e., adding the obtained B-layer solidified material to the mixed material of step (1) during the next melting separation to extract iron and rare earth from the rare earth iron ore, and then performing steps (2) to (3); wherein the amount of the B-layer solidified material added accounts for 1-50% of the total mass of the mixed material; (5) grinding the obtained C-layer solidified product to obtain a rare earth-rich powder with a particle size of less than 45 μm, adding the rare earth-rich powder to hydrochloric acid with a concentration of 6-12 mol / L, and performing a leaching treatment at 25-100° C. for 10-180 min, then separating the leaching solution and the leaching residue, the obtained leaching solution is a rare earth chloride leaching solution, and storing the leaching residue; (6) adding a precipitant solution to the rare earth chloride leaching solution to obtain a mixed solution, subjecting the mixed solution to a precipitation reaction at 20-100° C., and then separating the precipitate to obtain a mixed rare earth precipitate; the precipitant is selected from oxalic acid and / or carbonate.

2. The method according to claim 1, characterized in that in, The precipitant is oxalic acid; the pH of the mixed solution is 1-3, wherein the molar ratio of oxalic acid to rare earth chloride is 0.5-3:1, and the concentration of rare earth chloride is 1-10g / L; and the method further comprises: calcining the mixed rare earth precipitate at 800-1000°C for 1-3h to obtain a mixed rare earth oxide; and / or, the precipitant is carbonate; the pH of the mixed solution is 4-6, wherein the molar ratio of carbonate to rare earth chloride is 0.5-5:1, and the temperature of the precipitation reaction is 25-100°C.

3. The method according to claim 2, characterized in that The precipitant is oxalic acid, the temperature of the precipitation reaction is 40-60°C, the pH of the mixed solution is 1.5, wherein the concentration of rare earth chloride is 1-5g / L, the molar ratio of oxalic acid to rare earth chloride is 1.5-2:1, and / or, the roasting temperature is 950°C, and the roasting time is 1-2h; and / or, the precipitant is carbonate, the temperature of the precipitation reaction is 25-40°C; the pH of the mixed solution is 4.5, wherein the molar ratio of carbonate to rare earth chloride is 1.5-2:

1.

4. The method according to claim 1, characterized in that: in, The carbonate is selected from one or more of sodium carbonate, sodium bicarbonate, ammonium bicarbonate, and magnesium bicarbonate; and / or the reducing agent powder is selected from one or more of coal powder, graphite powder, carbon powder, and coke powder.

5. The method according to claim 1, characterized in that in, The mass of the reducing agent powder is 4-7% of the mass of the rare earth iron ore; and / or, in step (4), the mass of the B layer solidified material added each time is 1-50% of the mixed material; and / or, in step (5), the leaching treatment is carried out under stirring at a stirring rate of 300-1600r / min; and / or, in step (5), the rare earth-rich powder is added to hydrochloric acid with a concentration of 6-12mol / L to obtain a leaching system with a solid-liquid ratio of 1-30mg / L.

6. The method according to claim 5, characterized in that in, The mass of the B-layer solidified material is 10-20% of the mixed material; and / or the stirring rate is 500-800 r / min.

7. The method according to claim 1, characterized in that in, The holding temperature of the molten reduction treatment in step (1) is 1250-1400° C. and the holding time is 0.5-2 h; and / or, the centrifugal speed in step (2) is 2000-3000 r / min and the centrifugal treatment time is 10-30 min; and / or, the leaching treatment temperature in step (5) is 40-50° C., the solid-liquid ratio is 15-25 mg / L, the hydrochloric acid concentration is 6 mol / L, and the leaching treatment time is 60-90 min.

8. The method according to claim 1, characterized in that In the cutting separation, the cutting thickness of the A layer solidified material is 10-40% of the overall thickness of the hollow cylinder, the cutting thickness of the B layer solidified material is 10-40% of the overall thickness of the hollow cylinder, the cutting thickness of the C layer solidified material is 10-30% of the overall thickness of the hollow cylinder, and the cutting thickness of the D layer solidified material is 1-20% of the overall thickness of the hollow cylinder.

9. A device for implementing the method according to any one of claims 1 to 8, characterized in that: It includes: a high-temperature furnace for carrying out a melting reduction treatment on the mixed material; a centrifugal solidification machine for centrifugally treating the molten material and causing it to cool and solidify during the centrifugal treatment to form four layers of solidified material distributed in a concentric ring shape; and a cutting and separation device for cutting and separating the solidified material layers produced by the centrifugal solidification machine; wherein the centrifugal solidification machine includes an electric motor for providing power, a centrifugal solidification machine body connected to the electric motor through a transmission rod, a centrifugal solidification machine front cover located at the front end of the centrifugal solidification machine body and capable of being opened and closed, an equipment base for stably supporting the centrifugal solidification machine body, a slag chute for introducing the molten material into the centrifugal solidification machine body, and a slag chute having internal gears for adjusting the slag chute. The slag chute is a track-moving platform at the horizontal position of the slag chute; wherein the centrifugal separation solidification machine body is a centrifugal rotating machine provided with an internal cavity; the cavity wall of the internal cavity of the centrifugal separation solidification machine body and the trough surface of the slag chute are both formed by a composite layer material, and the composite layer material includes a steel material shell, an alumina refractory insulation material layer located in the steel material shell and having a refractory and heat-insulating effect, and a high-purity graphite layer located in the alumina refractory insulation material layer for solidification formation; the cutting and separation device includes a cutting head that can be extended into the internal cavity of the centrifugal separation solidification machine body, a cutting head drive motor connected to the cutting head through a shock-resistant tool rod, and a hydraulic lift that controls the up and down movement of the cutting head drive motor through a hydraulic pipe.

10. The device according to claim 9, characterized in that in, The centrifugal separation solidification machine body is provided with a heat dissipation shell, which is evenly distributed with heat dissipation fins; and / or, a support rail and a supporting pulley that can slide horizontally on the support rail are provided on the equipment base, and the centrifugal separation solidification machine body is arranged on the support rail through the supporting pulley; and / or, spiral blades are distributed on the cutting head, and there are two blade corners at the front end of the blade head. When performing cutting operations, the cutting head can rotate and move up and down with the blade drive motor; and / or, the slag chute and the cutting and separation device can be replaced on the track moving platform to add the molten material or cut and separate the solidified material as needed.

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