Multi-metal rare earth ore sulfating roasting clinker immersion cleaning integrated method

Abstract

The invention discloses a multi-metal rare earth ore sulfating roasting clinker immersion cleaning integrated method which comprises the following steps: slurrying sulfating roasting clinker of multi-metal rare earth ore concentrate powder, and carrying out a multi-stage countercurrent leaching-washing process on the obtained slurry to obtain overflow liquid containing rare earth metal. By means of the method, the concentration difference between the solution and the clinker in the leaching process can be increased, then the mass transfer driving force in the leaching process is improved, the leaching process is enhanced, and the dissolution rate of valuable metal is increased; and meanwhile, the washing purpose is synchronously achieved in the leaching process, the using amount of washing water is reduced, and the washing efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the field of hydrometallurgy, and relates to a method for leaching and washing sulfated roasted clinker, and specifically to an integrated method for leaching and washing sulfated roasted clinker of polymetallic rare earth ores. Background Art

[0002] There are about 169 known rare earth minerals, and more than 250 rare earth element minerals, but there are only a dozen industrially significant minerals used by the metallurgical industry, mainly fluorocarbon cerium ore, monazite, xenotime, weathering crust leaching ion adsorption type ore, etc. The lowest industrial grade of rare earth primary ore is 1.5% to 2.0%, and it needs to be concentrated and concentrated to obtain rare earth concentrate that meets the smelting requirements. Rare earth concentrates are generally made into various rare earth compound products by processes such as acid and alkali enhanced decomposition, leaching, purification, concentration or burning. The Baotou mixed rare earth ore composed of fluorocarbon cerium ore and monazite mainly adopts two treatment processes: acid method and alkali method. Among them, 90% of the Baotou rare earth ore is smelted by the third generation sulfuric acid method. The rare earth concentrate is mixed with concentrated sulfuric acid and roasted at high temperature in an internal heating rotary kiln. After roasting, the clinker is water-leached to extract rare earths. The water leaching adopts the traditional multi-stage stirring continuous leaching method: one-step slurry leaching uses more than 20 levels of 10m 3 The slurry is separated into solid and liquid after the reaction is completed. The leached residue obtained by solid-liquid separation is washed in two steps. The first and second washing processes also use multi-stage continuous leaching tanks. After the first washing, solid-liquid separation is carried out again. The first washing residue is slurried and solid-liquid separated. The entire leaching and washing process is long and complicated, and the equipment, labor, energy consumption and other costs and floor space are large.

[0003] Chinese patent CN105441675A discloses a method for efficient full-interface pump leaching of acid-process rare earth roasted ore, which adopts the method of clinker gravity sedimentation classification and full-interface pump leaching to strengthen the coarse particle leaching for the acid-process rare earth ore roasted clinker, which improves the leaching efficiency and leaching rate of the roasted ore to a certain extent. However, this method requires first classifying the clinker into coarse and fine particles, and then performing different leaching for the coarse and fine particles, and acid washing and other steps are required after leaching, which has the problems of long process flow, high equipment and energy consumption costs. Summary of the invention

[0004] In view of the technical difficulties in the prior art such as long leaching and washing process of sulfated roasted clinker, complicated operation, low washing efficiency and high water consumption, the purpose of the present invention is to provide an integrated method for leaching and washing complex rare earth ore sulfated roasted clinker with simple treatment process and high washing efficiency.

[0005] In order to achieve the above technical objectives, the present invention provides an integrated method for leaching and washing polymetallic rare earth ore sulfated roasted clinker, which comprises pulping the sulfated roasted clinker of the polymetallic rare earth ore concentrate powder, subjecting the obtained pulp to a multi-stage countercurrent leaching-washing process, and obtaining an overflow liquid containing rare earth metals; the process of the multi-stage countercurrent leaching-washing process is as follows: the pulp enters a first-stage settler and is mixed with part of the overflow liquid from a second-stage settler and then is settled, the concentrated underflow is drawn out from the bottom of the first-stage settler to a first-stage mixing tank and is mixed with part of the overflow liquid from a third-stage settler and then enters a second-stage settler, and is mixed with the remaining part of the overflow liquid from the third-stage settler and then is settled; the concentrated underflow The concentrated bottom flow in the n-1th stage settler is drawn out from the bottom of the n-1th stage settler to the n-1th stage mixing tank, mixed with part of the overflow liquid from the n+1th stage settler, and then enters the nth stage settler, mixed with the remaining overflow liquid from the n+1th stage settler, and then settles; and the bottom flow of the last stage settler is pumped to the filtration process by a slurry pump to obtain leached residue and filtrate; after the overflow liquid of the first stage settler flows out, it goes to the subsequent separation section for separation and recovery of valuable metals.

[0006] The technical solution of the present invention effectively connects sulphate roasting, pulping and leaching-washing in series, realizing the continuous feeding and discharging of polymetallic rare earth ore concentrate powder. The key lies in the use of a multi-stage countercurrent leaching-washing process, and the key to realizing the multi-stage countercurrent leaching-washing process lies in the setting of a settler and a mixer. In the present invention, the settler is used to separate the solid and solution in the mixed slurry. The slurry in the pulping tank enters the mixing cylinder of the central cylinder of the settler tangentially and is mixed with the overflow liquid, and enters the sedimentation body by gravity and inertia. The solution rises and overflows from the upper part of the settler, and the slurry settles and concentrates at the lower part; and the mixing tank is mainly used for fully mixing and washing the settled slurry and the overflow liquid.

[0007] The process principle of the technical solution of the present invention is: first, a paddle-type sulfation reactor is used for sulfation roasting, which, on the one hand, ensures the decomposition rate of valuable minerals in the concentrate during the roasting process, and on the other hand, the two paddles are rotated to grind the particles formed during the sulfation process, and the particle size of the sulfation roasting is controlled, which is conducive to the dissolution of valuable elements in the water leaching process. Since the decomposition of valuable minerals in the concentrate has been completed in the sulfation process, valuable metals such as rare earths and uranium have generated sulfates that are easily soluble in water. Therefore, the clinker is added to the returned solution for pulping, and the valuable metals are transferred into the solution by high speed strengthening, thereby realizing the pre-leaching process. However, the rare earth concentration, sulfate radical and impurity concentration in the clinker are high, and the solution viscosity of the traditional dissolution process is large and the mass transfer gradient is small, resulting in a slow dissolution rate. In view of this feature, the present invention integrates the clinker leaching and washing processes, adopts a countercurrent leaching-washing integrated process, and adds clinker and clean water from both ends to form a countercurrent leaching-washing process, thereby improving the leaching and washing effects. The added clean water acts as both a leaching agent and washing water, saving water consumption in the leaching process and reducing the amount of waste liquid to be treated in the subsequent metal separation process. In addition, the overflow liquid mixed in the mixing tank of the present invention is different from the conventional leaching process. The use of part of the overflow liquid of the n+1-stage settler and the concentrated underflow of the n-1-stage settler can increase the concentration difference between the solution and the clinker in the leaching process and improve the mass transfer efficiency of the leaching process. In particular, if the overflow liquid of the first-stage settler is directly returned to the pulping tank, the leaching and washing efficiency will be reduced because the overflow liquid contains high concentrations of valuable metals and impurities.

[0008] As a preferred solution, the sulfation roasted clinker is obtained by reacting polymetallic rare earth ore concentrate powder with concentrated sulfuric acid through a paddle-type sulfation reactor; the paddle-type sulfation reactor is composed of a stirring device and a cylinder, and the stirring device is composed of two counter-rotating hollow wedge-shaped blades, and a heating medium is passed through the hollow wedge-shaped blades. The stirring device composed of two counter-rotating hollow wedge-shaped blades of the paddle-type sulfation reactor of the present invention can not only stir the reaction materials and enhance the heat transfer effect of the materials, and its rotation speed is 1 to 8 rpm, but also can crush and grind the solidified materials to promote the reaction efficiency. The heating medium (such as heat transfer oil) mainly enters the hollow blades through the middle hole stirring shaft to heat the slurry.

[0009] As a preferred solution, the reaction conditions are: the mass ratio of polymetallic rare earth ore concentrate powder to concentrated sulfuric acid is 1: (0.6-2), the mass concentration of concentrated sulfuric acid is 90-98wt%, the temperature is 200-300°C, and the time is 1-4h; the particle size of the sulphate roasted clinker> 2mm accounts for no more than 5%. Within the reaction conditions of the present invention, the sulphate decomposition rate can reach more than 98%.

[0010] As a preferred solution, the content of valuable metals in the polymetallic rare earth ore concentrate powder is 10-65wt%.

[0011] As a preferred solution, the pulping is carried out in a pulping tank, the discharge of the paddle-type sulfation reactor is directly input into the pulping tank via a screw feeder, and is mixed with the remaining overflow liquid of the second-stage settler for pulping, and the pulp after pulping is transported to the first-stage settler by an underflow pump, and the process maintains continuous feeding and discharging. In the pulping process of the present invention, the remaining overflow liquid of the second-stage settler is used to maintain the solution balance of the overall system.

[0012] As a preferred solution, the solid-liquid ratio of the sulphation roasting clinker to the overflow liquid of the second-stage settler is 1kg: (0.6-1.5)L, the pulping temperature is 30-65°C, the residence time in the pulping tank is 5-30min, and the pulping tank speed is 350-550rpm. The present invention adopts strong stirring to achieve rapid mixing and pulping of materials, and since the decomposition of minerals has been completed in the sulphation roasting process to form sulfates, adding a solution can dissolve the valuable metal part into the solution, realizing the pre-impregnation process.

[0013] As a preferred solution, when n is an even number, flocculants are added to the first-stage settler, the n / 2-stage settler and the n-stage settler to promote sedimentation; when n is an odd number, flocculants are added to the first-stage settler, the (n+1) / 2-stage settler and the n-stage settler to promote sedimentation. The flocculant addition site provided in the present invention can achieve the best sedimentation effect while reducing the amount of flocculants used.

[0014] As a preferred solution, the flocculant is an amphoteric flocculant and / or a cationic polyacrylamide flocculant; the amount of the flocculant added is 20 to 100 L per cubic meter of slurry entering the settler, and the concentration of the flocculant solution is 0.05 to 0.2 wt%.

[0015] As a preferred solution, n is an integer of 4 to 6, the pulp concentration after settling in each settling tank is 50 to 60wt%, the remaining overflow liquid added to each mixing tank is 10 to 60wt% of the total overflow liquid of the n+2th stage, the material stays in the mixing tank for 5 to 20 minutes, and the pulping tank speed is 350 to 550rpm. Although each stage has a certain leaching and washing effect in the multi-stage countercurrent leaching-washing process, the leaching effect is dominant in the early stage and the washing effect is dominant in the later stage. For this reason, by controlling the return amount of the mixing tank solution, the residence time, the stirring speed, etc., the leaching efficiency is improved by strong stirring and long residence time in the early stage; the later washing process can achieve the ideal effect under weaker conditions. In order to reduce the size of the mixing tank, the energy consumption of the equipment, etc., the return amount of the mixing tank solution, the residence time, the stirring speed, etc. can be appropriately reduced. The amount of solution added to each mixing tank is 10-60wt% of the total overflow of the n+1th stage. Furthermore, the return amount from the first stage to the last stage shows a decreasing trend. For example, if 6 stages are adopted, the optimal return ratios of stages 1 to 6 are 50%, 40%, 35%, 20%, 20%, and 15%; the residence time of the slurry in the mixing tank is 15min, 10min, 10min, 8min, 8min, and 5min respectively; the stirring speeds of the mixing tank are 550rpm, 500rpm, 500rpm, 400rpm, 350rpm, and 350rpm respectively.

[0016] As a preferred solution, clean water is added to the n-1 stage mixing tank and the n stage settler, and the amount of clean water added is 3 to 6 times the mass of the sulphate roasted clinker. The specific amount of clean water added is to control the rare earth concentration REO in the overflow liquid of the first stage settler to maintain 40 to 60 g / L, and the REO concentration in the bottom flow of the last stage settler is reduced to less than 10 mg / L.

[0017] As a preferred solution, the bottom flow of the last stage settler is pumped to the filtration process by a slurry pump. The filtration is carried out by a vacuum filter or a filter press, and the leached residue is sent to the tailings storage for storage. The moisture content of the leached residue after filtration is 15% to 25%; the filtrate is pumped to the n-1 stage mixing tank.

[0018] Compared with the prior art, the present invention has the following technical effects:

[0019] 1) The technical solution of the present invention adopts a multi-stage countercurrent leaching-washing process to increase the concentration difference between the solution and the clinker in the leaching process, thereby improving the mass transfer driving force in the leaching process, strengthening the leaching process, and increasing the dissolution rate of valuable metals; at the same time, the washing purpose is also achieved in the leaching process, the amount of washing water is reduced, and the washing efficiency is improved. Compared with conventional operations, the recovery rate of valuable elements is increased by 1-3%, and the water consumption is reduced by more than 10%.

[0020] 2) The present invention effectively connects sulfuric acid roasting, pulping and leaching-washing in series, realizes the continuous feeding and discharging of polymetallic rare earth ore concentrate powder, and improves the continuity and stability of operation. In addition, the present invention does not need to perform step-by-step leaching and acid washing for roasted clinker of different particle sizes through sedimentation classification, which greatly simplifies the process flow.

[0021] 3) The present invention uses a paddle-type sulfation reactor to simultaneously achieve the decomposition and grinding of valuable minerals, and also achieves the decomposition and pretreatment process of polymetallic rare earth ore concentrate powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The invention discloses a process flow of an integrated method for sulphate roasting clinker leaching of polymetallic rare earth ores.

[0023] Figure 2 The present invention is a flow chart of an integrated method for sulphate roasting clinker leaching of polymetallic rare earth ores. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of the present invention, the present invention will be described in more comprehensive and detailed manner in conjunction with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0025] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0026] Unless otherwise specified, all reagents and raw materials used in the present invention are commercially available products or products that can be prepared by known methods.

[0027] Example 1

[0028] A complex polymetallic rare earth concentrate containing minerals such as yttrium silicate, bastnaesite, monazite, etc., with a uranium grade of 0.045%, a rare earth oxide content of 21wt%, a Fe2O3 content of 19.9wt%, and a SiO2 content of 32wt%.

[0029] The complex multi-metallic rare earth ore concentrate powder and concentrated sulfuric acid (concentrated sulfuric acid mass concentration 92wt%) are mixed at a mass ratio of 1:0.95. After mixing evenly, the materials are added to the sulfation reactor through a spiral, and the sulfation decomposition reaction is carried out at a temperature of 250°C for 2.5 hours. The decomposition rate of rare earth minerals by sulfation decomposition can reach 98.6%, the decomposition rate of uranium-containing minerals can reach 92.5%, the hollow blade speed is 3rpm, and the proportion of clinker discharge particle size>2mm is 4%.

[0030] The discharge from the sulfation reactor is directly fed into the pulping tank through a screw feeder, and mixed with the overflow liquid of the second-stage settler for pulping. After pulping, the pulp is transported to the first-stage settler by an underflow pump. This process maintains continuous feeding and discharging. The pulping liquid-solid ratio is clinker: the solid-liquid ratio of the overflow liquid of the second-stage settler = 1kg:0.65L, the pulping temperature is 50°C, the material stays in the pulping tank for 10min, the pulping tank speed is 550rpm, and strong stirring is used to achieve rapid mixing, pulping, and pre-impregnation of the materials.

[0031] A five-stage countercurrent leaching-washing process is adopted: the pre-impregnated slurry enters the central cylinder of the first-stage settler and is mixed with the overflow liquid and flocculant solution of the second stage. The flocculant is an amphoteric polyacrylamide flocculant FZ3802, the concentration of the flocculant solution is 0.05wt%, and the amount of flocculant solution added per cubic slurry is 80L. After mixing in the central cylinder, the slurry enters the settler by gravity, and the solution rises and overflows from the upper part of the settler to the subsequent separation section for valuable metal separation and recovery. The slurry settles and concentrates at the bottom. After concentration, the slurry concentration is 55wt%, and it is pumped out to the first-stage mixing tank by the bottom slurry pump, and mixed with a part of the overflow of the third-stage settler (25wt% of the total overflow) at a speed of 500rpm, and the slurry is kept in the mixing tank for 15min. The mixed slurry is then pumped to the second-stage settler and mixed with the remaining third-stage overflow liquid. After mixing in the central tube, the slurry enters the second-stage settler by gravity, and the solution rises and overflows from the upper part of the second-stage settler to the pulping tank and the first settler. The slurry settles and concentrates at the bottom. After concentration, the slurry concentration is 55wt%, and it is pumped out to the second-stage mixing tank by the bottom slurry pump, and mixed with a part of the overflow of the fourth-stage settler (25wt% of the total overflow) at a speed of 400rpm, and the slurry is kept in the second-stage mixing tank for 10min. The mixed slurry is then pumped to the third-stage settler and mixed with the remaining fourth-stage overflow liquid and flocculant solution. The subsequent operations of the third, fourth, and fifth stages are the same as above.

[0032] Clean water is added to the fifth-stage mixing tank and the fifth-stage settler. The amount of clean water added is 3.12 times the mass of the sulfation roasted clinker. The rare earth concentration REO in the first-stage overflow liquid is 42g / L, and the REO concentration in the bottom flow of the last-stage settler is 5mg / L.

[0033] The third and fifth stage flocculants also use amphoteric polyacrylamide flocculant FZ3802, the concentration of the flocculant solution is 0.05%, and the third and fifth stage flocculants are added in amounts of 50L and 80L per cubic meter of slurry, respectively.

[0034] The bottom flow of the fifth-stage settler is pumped to the filtration process by the slurry pump. The filtration adopts a vacuum filter, and the leached slag is sent to the tailings storage for storage. The moisture content of the leached slag after filtration is 22%; the filtrate is pumped to the fourth-stage mixing tank for slurrying.

[0035] Comparative Example 1

[0036] The same complex multi-metal rare earth concentrate as in Example 1 was mixed with 92wt% concentrated sulfuric acid, the mass ratio of concentrate powder to concentrated sulfuric acid was 1:0.95, and after uniform mixing, the material was added to the internal heating rotary kiln for high-temperature roasting via a spiral, the roasting temperature was 250°C, and the reaction time was 2.5h. After roasting, the clinker entered the pulping tank, and slag washing water was added for pulping; after pulping, it was pumped to a 6-stage stirring tank, and clean water was added to adjust the liquid-solid ratio to 5L:1kg, and the residence time in the continuous leaching tank was 4h. After the leaching reaction, it was pumped to a plate-frame filter press for solid-liquid separation to obtain a water leaching liquid and a leached slag; the leached slag was stirred and washed twice to recover the valuable elements. The first slag washing liquid was returned for leaching the roasted clinker, and the second slag washing liquid was returned for the first slag washing. Clean water was used for the second slag washing. The solid ratio of the washing slurry was 4L:1kg, and the stirring and washing time was 2h. After washing, a plate-frame filter press was used for solid-liquid separation.

[0037] The technical indicators and rare earth element recovery rates of Example 1 and Comparative Example 1 are shown in Table 1.

[0038] Table 1

[0039]

[0040] Example 2

[0041] A uranium-niobium rare earth concentrate containing minerals such as monazite, fluorocarbon cerium ore, and columbite, the uranium content of the concentrate is 0.058%, the rare earth oxide content is 45.2wt%, and the niobium pentoxide content is 3.5wt%.

[0042] The complex multi-metallic rare earth ore concentrate powder and concentrated sulfuric acid (concentrated sulfuric acid mass concentration 95wt%) are mixed and pulped at a mineral acid mass ratio of 1:1.2. After mixing evenly, the materials are added to the paddle-type sulfation reactor through a spiral, and the sulfation decomposition reaction is carried out at a temperature of 280°C for 1.5 hours. The decomposition rate of rare earth minerals by sulfation decomposition can reach 99.2%, and the decomposition rate of uranium-containing niobium minerals can reach 95.3%. The hollow paddle speed is 5rpm, and the proportion of clinker discharge particle size>2mm is 4.2%.

[0043] The discharge of the paddle-type sulfation reactor is directly fed into the pulping tank through a screw feeder, and mixed with the overflow liquid of the second-stage settler for pulping. After pulping, the pulp is transported to the first-stage settler by an underflow pump. This process maintains continuous feeding and discharging. The pulping liquid-solid ratio is clinker: the solid-liquid ratio of the overflow liquid of the second-stage settler = 1kg:1.2L, the pulping temperature is 55°C, the material stays in the pulping tank for 20min, the pulping tank speed is 450rpm, and strong stirring is used to achieve rapid mixing, pulping, and pre-impregnation of the material.

[0044] A 6-stage countercurrent leaching-washing process is adopted: the pre-impregnated slurry enters the central cylinder of the first-stage settler and is mixed with the overflow liquid and flocculant solution of the second stage. The flocculant is a cationic polyacrylamide flocculant CZ5002, the concentration of the flocculant solution is 0.1wt%, and the amount of flocculant solution added per cubic slurry is 100L. After mixing in the central cylinder, the slurry enters the settler by gravity, and the solution rises and overflows from the upper part of the settler to the subsequent separation section for valuable metal separation and recovery. The slurry settles and concentrates at the bottom. After concentration, the slurry concentration is 52wt%, and it is pumped out to the first-stage mixing tank by the bottom slurry pump, and mixed with a part of the overflow of the third-stage settler (40wt% of the total overflow) at a speed of 500rpm, and the slurry is kept in the mixing tank for 15min. The mixed slurry is then pumped to the second-stage settler and mixed with the remaining third-stage overflow liquid. After mixing in the central tube, the slurry enters the second-stage settler by gravity, and the solution rises and overflows from the upper part of the settler to the pulping tank and the first settler. The slurry settles and concentrates at the bottom. After concentration, the slurry concentration is 52wt%, and it is pumped out to the second-stage mixing tank by the bottom slurry pump, and mixed with a part of the overflow of the fourth-stage settler (40wt% of the total overflow) at a speed of 400rpm, and the slurry is kept in the second-stage mixing tank for 10min. The mixed slurry is then pumped to the third-stage settler and mixed with the remaining fourth-stage overflow liquid and flocculant solution. The subsequent operations of the third, fourth, fifth, and sixth stages are the same as above.

[0045] Clean water is added to the sixth-stage mixing tank and the sixth-stage settler. The amount of clean water added is 3.12 times the mass of the sulfation roasted clinker. The rare earth concentration REO in the first-stage overflow liquid is 50g / L, and the REO concentration in the bottom flow of the last-stage settler is 8mg / L.

[0046] The third and sixth stage flocculants also use cationic polyacrylamide flocculant CZ5002, the concentration of flocculant solution is 0.1%, and the third and sixth stage flocculants are added in amounts of 20L and 50L per cubic meter of slurry, respectively.

[0047] The bottom flow of the sixth-stage settler is pumped to the filtration process by a slurry pump. The filtration is carried out using a filter press, and the leached residue is sent to the tailings storage for storage. The moisture content of the leached residue after filtration is 18%; the filtrate is pumped to the fifth-stage mixing tank for slurrying.

[0048] Comparative Example 2

[0049] The same uranium-niobium rare earth concentrate as in Example 2 was mixed with 95wt% concentrated sulfuric acid, the mass ratio of concentrate powder to concentrated sulfuric acid was 1:1.2, and after uniform mixing, the material was added to the internal heating rotary kiln for high-temperature roasting through a spiral, the roasting temperature was 280°C, and the reaction time was 1.5h. After roasting, the clinker entered the pulping tank, and slag washing water was added for pulping; after pulping, it was pumped to a 6-stage stirring tank, and clean water was added to adjust the liquid-solid ratio to 5L:1kg, and the residence time in the continuous leaching tank was 4h. After the leaching reaction, it was pumped to a plate-frame filter press for solid-liquid separation to obtain a water leaching liquid and a leached slag; the leached slag was stirred and washed twice to recover the valuable elements. The first slag washing liquid was returned for leaching the roasted clinker, and the second slag washing liquid was returned for the first slag washing. Clean water was used for the second slag washing. The solid ratio of the washing slurry was 4L:1kg, and the stirring and washing time was 2h. After washing, a plate-frame filter press was used for solid-liquid separation.

[0050] The technical indicators and rare earth element recovery rates of Example 2 and Comparative Example 2 are shown in Table 2.

[0051] Table 2

[0052]

Claims

1. An integrated method for sulphate roasting clinker leaching of polymetallic rare earth ores, characterized in that: The sulphate-roasted clinker of the polymetallic rare earth ore concentrate powder is pulped, and the obtained pulp is subjected to a multi-stage countercurrent leaching-washing process to obtain an overflow liquid containing rare earth metals; The process of the multi-stage countercurrent leaching-washing process is as follows: the slurry enters the first-stage settler and is mixed with part of the overflow liquid from the second-stage settler before settling; the concentrated underflow is drawn from the bottom of the first-stage settler to the first-stage mixing tank and mixed with part of the overflow liquid from the third-stage settler before entering the second-stage settler and mixing with the remaining overflow liquid from the third-stage settler before settling; the concentrated underflow is drawn from the bottom of the second-stage settler to the second-stage mixing tank and mixed with part of the overflow liquid from the fourth-stage settler. After mixing with the liquid, it enters the third-stage settler and is mixed with the remaining overflow liquid from the fourth-stage settler for sedimentation; by analogy, the concentrated underflow in the n-1-stage settler is drawn out from the bottom of the n-1-stage settler to the n-1-stage mixing tank and mixed with part of the overflow liquid of the n+1-stage settler, and then enters the n-stage settler and is mixed with the remaining overflow liquid from the n+1-stage settler for sedimentation; and the underflow of the last-stage settler is sent to the filtration process by the slurry pump to obtain leached residue and filtrate; After the overflow liquid of the first-stage settler flows out, it goes to the subsequent separation section for separation and recovery of valuable metals.

2. The integrated method for sulphation roasting clinker leaching of polymetallic rare earth ore according to claim 1, characterized in that: The sulphate roasted clinker is obtained by reacting polymetallic rare earth ore concentrate powder with concentrated sulfuric acid in a paddle-type sulphate reactor; The paddle-type sulfation reactor is composed of a stirring device and a cylinder. The stirring device is composed of two hollow wedge-shaped paddles rotating in opposite directions, and a heating medium is passed through the hollow wedge-shaped paddles.

3. The integrated method for sulphation roasting clinker leaching of polymetallic rare earth ore according to claim 2, characterized in that: The reaction conditions are as follows: the mass ratio of the polymetallic rare earth ore concentrate powder to concentrated sulfuric acid is 1:(0.6-2), the mass concentration of concentrated sulfuric acid is 90-98wt%, the temperature is 200-300°C, and the time is 1-4h; the particle size of the sulfated roasted clinker >2mm accounts for no more than 5%.

4. The integrated method for sulphation roasting clinker leaching of polymetallic rare earth ore according to claim 2, characterized in that: The pulping is carried out in a pulping tank, the discharge of the paddle-type sulfation reactor is directly fed into the pulping tank via a screw feeder, and mixed with the remaining overflow liquid of the second-stage settler for pulping, and the pulp after pulping is transported to the first-stage settler by an underflow pump, and the process maintains continuous feeding and discharging; The solid-liquid ratio of the sulphate-roasted clinker to the overflow liquid of the second-stage settler is 1kg:(0.6-1.5)L, the pulping temperature is 30-65°C, the residence time in the pulping tank is 5-30min, and the pulping tank rotation speed is 350-550rpm.

5. The integrated method for sulphation roasting clinker leaching of polymetallic rare earth ore according to claim 4, characterized in that: When n is an even number, flocculants are added to the first-stage settler, the n / 2-stage settler and the n-stage settler to promote sedimentation; when n is an odd number, flocculants are added to the first-stage settler, the (n+1) / 2-stage settler and the n-stage settler to promote sedimentation.

6. The integrated method for sulphation roasting clinker leaching of polymetallic rare earth ore according to claim 5, characterized in that: The flocculant is an amphoteric flocculant and / or a cationic polyacrylamide flocculant; The amount of the flocculant added is 20 to 100 L per cubic meter of slurry entering the settler.

7. The integrated method for sulphation roasting clinker leaching of polymetallic rare earth ore according to any one of claims 1 to 6, characterized in that: The n is an integer of 4 to 6, the pulp concentration after settling in each settling tank is 50 to 60wt%, the remaining overflow liquid added to each mixing tank is 10 to 60wt% of the total overflow liquid of the n+2th stage, the material stays in the mixing tank for 5 to 20 minutes, and the pulping tank speed is 350 to 550rpm.

8. The integrated method for sulphation roasting clinker leaching of polymetallic rare earth ore according to claim 7, characterized in that: Clean water is added to the n-1th stage mixing tank and the nth stage settler, wherein the amount of clean water added is 3 to 6 times the mass of the sulphate roasted clinker.

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