Process for the treatment of phosphorus-containing rare earth ores and use of chlorinated polyolefin materials

Abstract

The application discloses a treatment method of phosphorus-containing rare earth ore and application of chlorinated polyolefin material. The treatment method comprises the following steps: (1) roasting a mixture comprising chlorinated polyolefin material and phosphorus-containing rare earth ore at 500-900 DEG C to obtain a roasting product; and (2) water immersion of the roasting product to obtain a rare earth solution. The treatment method has a high decomposition rate.

Description

Technical Field

[0001] This invention relates to a method for processing phosphorus-containing rare earth minerals and the use of chlorinated polyolefin materials. Background Technology

[0002] On the one hand, the main methods for processing rare earth concentrates include acid methods, alkaline methods, oxidative roasting methods, and chlorination decomposition methods. Acid methods and subtractive methods produce more wastewater, while oxidative roasting methods easily oxidize trivalent cerium to tetravalent cerium and produce more waste gas.

[0003] CN116732363A discloses a method for processing phosphorus-containing rare earth ore, comprising the following steps: roasting a raw material including phosphorus-containing rare earth ore and magnesium chloride at 600–900°C to obtain roasted ore; leaching the roasted ore with ammonium citrate solution to obtain a phosphorus-containing solution and rare earth filter residue; adjusting the pH of the phosphorus-containing solution to 7.5–10 to obtain magnesium ammonium phosphate; and leaching the rare earth filter residue with hydrochloric acid to obtain a rare earth chloride solution. This method requires acid leaching, resulting in a large amount of waste liquid.

[0004] CN1348997A discloses a method for decomposing rare earth concentrates. This method uses calcium oxide and sodium chloride as a roasting aid, with the aid amount being 5–30 wt%. The roasting temperature is 600–950℃, and the roasting time is 10–90 minutes. This method achieves a high oxidation rate of cerium.

[0005] CN117587271A discloses a method for processing mixed rare earth concentrates. This method uses chlorine gas as a chlorinating agent and requires carbon monoxide as a reducing agent; these substances are highly toxic to humans.

[0006] On the other hand, PVC (polyvinyl chloride) is an important material in modern industry and daily life, widely used in the construction, electrical and electronics, medical, and packaging industries. Therefore, a large amount of PVC waste is generated. Currently, the main methods for recycling PVC are landfill, incineration, and recycling. Landfilling or incineration easily causes secondary pollution. Recycling requires dechlorination and catalytic pyrolysis, which is expensive. How to effectively utilize waste PVC has become an urgent problem to be solved. Summary of the Invention

[0007] In view of this, one object of the present invention is to provide a method for processing phosphorus-containing rare earth ores. This method utilizes chlorinated polyolefin materials to improve the decomposition rate of rare earth concentrates. Furthermore, this method can reduce the oxidation rate of cerium. Even further, this processing method enables the reuse of waste polymer-containing products, reducing the environmental pollution caused by waste polymer-containing products. Another object of the present invention is to provide a use for chlorinated polyolefin materials.

[0008] The above objectives are achieved through the following technical solutions.

[0009] On one hand, the present invention provides a method for processing phosphorus-containing rare earth ore, comprising the following steps:

[0010] (1) A mixture including chlorinated polyolefin material and phosphorus rare earth ore is roasted at 500-900°C to obtain roasted product;

[0011] (2) The roasted product was soaked in water to obtain a rare earth solution.

[0012] According to the processing method of the present invention, preferably, the chlorinated polyolefin material is a polymer formed by polymerization of monomers including chlorinated olefins or an article containing such polymer.

[0013] According to the processing method of the present invention, preferably, the chlorinated olefin is as shown in formula (I):

[0014]

[0015] R1, R3, R5 and R7 are each independently selected from C1 to C6 alkylene groups or single bonds, R2, R4, R6 and R8 are each independently selected from H or Cl, and at least one of R2, R4, R6 and R8 is Cl.

[0016] According to the processing method of the present invention, preferably, R1, R3, R5 and R7 are independently selected from methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, sec-butylene, tert-butylene, n-pentylene, methylbutylene, dimethylpropylene, ethylpropylene, n-ethylene, methylpentylene, ethylbutylene, dimethylbutylene, and single bond.

[0017] According to the processing method of the present invention, preferably, the rare earth element content in the phosphorus-containing rare earth ore is greater than or equal to 50 wt%, wherein the rare earth element content is calculated as REO;

[0018] The mass ratio of phosphorus-containing rare earth ore to chlorinated polyolefin material is 1:(4-9). The mass of phosphorus-containing rare earth ore is calculated by converting the rare earth elements it contains into the mass of the rare earth oxides corresponding to those rare earth elements. The mass of chlorinated polyolefin material is calculated by the polymer it contains.

[0019] According to the processing method of the present invention, preferably, in step (1), the mixture further contains one or more of the following substances: water glass, carboxymethyl cellulose, bentonite, starch, lignin, alkaline earth metal oxides, and alkaline earth metal hydroxides; the content of the above substances is 0.1 to 3 wt%.

[0020] According to the processing method of the present invention, preferably, in step (2), water and calcined product are mixed at a volume ratio of (1-10):1 and soaked in water at 50-90°C for 0.5-3 hours.

[0021] On the other hand, the present invention provides the use of chlorinated polyolefin materials in the decomposition of phosphorus-containing rare earth ores.

[0022] According to the use of the invention, preferably, the chlorinated polyolefin material is a polymer formed by polymerization of monomers including chlorinated olefins or an article containing such polymer.

[0023] According to the present invention, preferably, the phosphorus-containing rare earth ore contains at least one of monazite or xenotime.

[0024] This invention involves roasting phosphorus-containing rare earth ore with chlorinated polyolefin material under appropriate conditions, thereby chlorinating and decomposing the rare earth minerals. The chloride salts produced by the chlorinated polyolefin material at high temperatures fix phosphorus and other resources in the phosphorus-containing rare earth ore in solid form, achieving separation from the rare earth elements. The method of this invention allows cerium in the phosphorus-containing rare earth ore to exist in a trivalent form, reducing the oxidation rate of cerium. This invention allows for the extraction of a rare earth solution by leaching the roasted product with water, reducing acid consumption. The chlorinated polyolefin material of this invention can be provided from waste products containing this polymer, thus reducing the difficulty of recycling waste polymer products and environmental pollution, as well as lowering the cost of mineral decomposition. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0026] The phosphorus-containing rare earth ore of this invention refers to a rare earth ore containing phosphorus, which can be monazite or xenotime, or a mixed rare earth ore. The content of monazite and / or xenotime in the mixed rare earth ore is ≥5 wt%; preferably, the content of monazite and / or xenotime is ≥10 wt%. In some embodiments, the content of monazite and / or xenotime in the mixed rare earth ore is 10–40 wt%. In addition to monazite and / or xenotime, the mixed rare earth ore may also contain bastnaesite. In some embodiments, the phosphorus-containing rare earth ore is a mixture of monazite and bastnaesite. Generally, the phosphorus-containing rare earth ore is preferably monazite concentrate. Concentrate refers to the product obtained by processing the raw ore. These processing methods are well known in the art and will not be described further here.

[0027] The chlorinated polyolefin material of this invention refers to a material in which some or all of the hydrogen elements of a polyolefin are replaced by chlorine. Chlorinated polyolefins can be obtained by chlorination of polyolefins, or by polymerization of chlorinated olefin monomers with other comonomers, or by polymerization of chlorinated olefin monomers. The chlorinated polyolefin material can be a polymer, or an article containing the aforementioned polymer and other excipients / auxiliaries.

[0028] The green body of this invention represents a preform formed by pressing a mixture. It is typically necessary to press the mixture into a green body before roasting the rare earth ore. Pressing methods are well known in the art and will not be described in detail here.

[0029] <Processing methods for phosphorus-containing rare earth ores>

[0030] The method for processing phosphorus-containing rare earth ores according to the present invention includes the following steps: (1) roasting; and (2) water leaching. These will be described in detail below.

[0031] roasting steps

[0032] The present invention involves calcining a mixture comprising chlorinated polyolefin material and phosphorus-containing rare earth minerals at 500–900°C to obtain a calcined product.

[0033] In some embodiments, the chlorinated polyolefin material is a polymer formed by polymerization of monomers including chlorinated olefins or an article containing such polymer. Chlorinated olefins are shown in formula (I).

[0034]

[0035] In formula (I), R1, R3, R5 and R7 are each independently selected from C1 to C6 alkylene groups or single bonds, R2, R4, R6 and R8 are each independently selected from H and Cl, and at least one of R2, R4, R6 and R8 is Cl.

[0036] In this invention, R1, R3, R5, and R7 are each independently selected from C1-C6 alkylene groups or single bonds. Preferably, R1, R3, R5, and R7 are each independently selected from C1-C3 alkylene groups or single bonds. In some embodiments, R1, R3, R5, and R7 are each independently selected from methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, sec-butylene, tert-butylene, n-pentylene, methylbutylene, dimethylpropylene, ethylpropylene, n-ethylene, methylpentylene, ethylbutylene, dimethylbutylene, and single bonds.

[0037] According to one embodiment of the present invention, R1, R3, R5, and R7 are all single bonds. When R1 is a single bond, R2 and C are directly connected by a single bond. The same applies when R3, R5, and R7 are single bonds.

[0038] In this invention, R2, R4, R6, and R8 are each independently selected from H and Cl, and at least one of R2, R4, R6, and R8 is Cl. In some embodiments, two of R2, R4, R6, and R8 are Cl. In other embodiments, one of R2, R4, R6, and R8 is Cl.

[0039] The polymer of the present invention is formed by polymerization of the monomers represented by formula (I). The polymerization is specifically an addition polymerization reaction. The polymer of the present invention may be selected from one or more of polyvinyl chloride, polyvinylidene chloride, and polytetrachloroethylene. According to one embodiment of the present invention, the polymer is polyvinyl chloride.

[0040] The articles containing the polymer of the present invention can be waste products. In the articles containing the polymer, the content of the polymer is greater than or equal to 30 wt%; preferably, greater than or equal to 40 wt%; more preferably, greater than or equal to 50 wt%; and most preferably, greater than or equal to 70 wt%.

[0041] In some embodiments, the polymer article may also contain a chlorine-free polymer, such as ester compounds. Ester compounds include, but are not limited to, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, dibutyl phthalate, dipentyl phthalate, dihexyl phthalate, diheptyl phthalate, dioctyl phthalate, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, dibutyl phthalate, dipentyl phthalate, dihexyl phthalate, diheptyl phthalate, dioctyl phthalate, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, dibutyl phthalate, dipentyl phthalate, dihexyl phthalate, diheptyl phthalate, and dioctyl phthalate. The content of these polymers can be less than or equal to 40 wt%; preferably, less than or equal to 20 wt%; more preferably, less than or equal to 10 wt%. For example, 3 to 7 wt%.

[0042] In some embodiments, the polymer article may also contain alkaline earth metal stearates. Examples include calcium stearate, magnesium stearate, and barium stearate. The content of the alkaline earth metal stearate may be less than or equal to 40 wt%; preferably, less than or equal to 20 wt%; more preferably, less than or equal to 10 wt%. For example, 3–7 wt%.

[0043] In some embodiments, the polymer article may also contain alkaline earth metal carbonates. For example, calcium carbonate, magnesium carbonate, barium carbonate, etc. The content of alkaline earth metal carbonates may be less than or equal to 40 wt%; preferably, less than or equal to 20 wt%; more preferably, less than or equal to 10 wt%. For example, 3–7 wt%.

[0044] Products containing this polymer include, but are not limited to, pipes, window frames, wires, cable insulation, infusion bags, catheters, surgical instruments, packaging bags, and packaging paper.

[0045] The particle size of the chlorinated polyolefin material can be less than 200 mesh; preferably less than 300 mesh; more preferably less than 400 mesh.

[0046] In this invention, the phosphorus-containing rare earth ore contains at least one of monazite and xenotime. Preferably, the phosphorus-containing rare earth ore contains monazite. More preferably, the phosphorus-containing rare earth ore is monazite. In some embodiments, the phosphorus-containing rare earth ore can be a mixed rare earth ore. In the mixed rare earth ore, the content of monazite and / or xenotime is ≥5 wt%; preferably, the content of monazite and / or xenotime is ≥10 wt%. In some embodiments, the content of monazite and / or xenotime in the mixed rare earth ore is 10-40 wt%. In addition to monazite and / or xenotime, the mixed rare earth ore may also contain bastnaesite. In some embodiments, the phosphorus-containing rare earth ore is a mixture of monazite and bastnaesite.

[0047] The phosphorus-containing rare earth ore is a phosphorus-containing rare earth concentrate. The rare earth element content in the phosphorus-containing rare earth ore is greater than or equal to 50 wt%; preferably, the rare earth element content in the phosphorus-containing rare earth ore is greater than or equal to 60 wt%. The mass of rare earth elements is expressed as REO.

[0048] The particle size of the phosphorus-containing rare earth ore can be less than 200 mesh; preferably less than 300 mesh; more preferably less than 400 mesh.

[0049] The mass ratio of phosphorus-containing rare earth ore to chlorinated polyolefin material can be 1:(4-9); preferably 1:(5-8); more preferably 1:(5-6). The mass of phosphorus-containing rare earth ore is calculated by converting the rare earth element it contains into the mass of the corresponding rare earth oxide. The mass of chlorinated polyolefin material is calculated by the mass of the polymer it contains.

[0050] The mixture of the present invention may further contain one or more of water glass, carboxymethyl cellulose, bentonite, starch, lignin, alkaline earth metal oxides, and alkaline earth metal hydroxides. The alkaline earth metal oxides may be selected from one or more of magnesium oxide, calcium oxide, and barium oxide. The alkaline earth metal hydroxides may be selected from one or more of magnesium hydroxide, calcium hydroxide, and barium hydroxide. According to one embodiment of the present invention, the mixture further contains calcium hydroxide (slaked lime). The content of the above substances in the mixture may be 0.1–3 wt%; preferably 0.5–2.5 wt%; more preferably 1.5–2 wt%. Preferably, the mixture of the present invention is composed of a polymer, a phosphorus-containing rare earth ore, and the above substances.

[0051] In some embodiments, the raw material can be formed into a blank before firing. The diameter of the blank can be 10–30 mm; preferably 12–25 mm; more preferably 15–20 mm. When the blank is spherical, the above diameter is the diameter of the sphere. When the blank is non-spherical, the diameter is the diameter of the smallest enclosing sphere. Non-spherical shapes include cuboids, cubes, rods, and irregular shapes.

[0052] The roasting temperature is 500–900℃; preferably 600–850℃; more preferably 700–800℃.

[0053] The roasting time can be 0.5 to 4 hours; preferably 1 to 3 hours; more preferably 2 to 2.5 hours.

[0054] The heating rate from the initial temperature to the calcination temperature can be 0.5–30 °C / min; preferably 0.5–20 °C / min; more preferably 1–10 °C / min.

[0055] Firing can be carried out in a rotary kiln.

[0056] The blank can be dried before firing. The drying temperature can be 40-120℃; preferably 45-100℃; more preferably 50-70℃.

[0057] The drying time can be 0.5 to 4 hours; preferably 1 to 3 hours; more preferably 1 to 2 hours.

[0058] In some embodiments, the process further includes the step of preparing a preform: mixing a chlorinated polyolefin material with a phosphorus-containing rare earth ore, then grinding the mixture to obtain a ground product. The ground product is then mixed with other raw materials to obtain a premix. The premix is ​​then manufactured into a preform.

[0059] Steps of soaking in water

[0060] This invention involves leaching the calcined product with water to obtain a rare earth solution. Alternatively, the rare earth solution can be obtained directly from the calcined product through water leaching. In this invention's method, the calcined product does not require acid leaching. This invention's method does not include an acid leaching step. This invention's method eliminates the need for acid, thus reducing costs.

[0061] The present invention involves soaking the roasted product in water at 50–90°C; preferably, soaking the roasted product in water at 50–85°C; more preferably, soaking the roasted product in water at 60–80°C.

[0062] The immersion time can be 0.5 to 3 hours; preferably 0.8 to 1.8 hours; more preferably 1 to 1.5 hours.

[0063] The liquid-to-solid ratio can be (1-10):1; preferably (2-8):1; more preferably (3-6):1. The liquid-to-solid ratio refers to the volume ratio of water to the calcined product.

[0064] The decomposition rate of the phosphorus-containing rare earth ore is greater than or equal to 80 wt%; preferably, it is greater than or equal to 85 wt%.

[0065] The oxidation rate of cerium is ≤1 wt%; preferably, the oxidation rate of cerium is ≤0.8 wt%; more preferably, the oxidation rate of cerium is ≤0.7 wt%.

[0066] <Uses of Polymers>

[0067] This invention provides the use of a chlorinated polyolefin material in the decomposition of phosphorus-containing rare earth ores. Preferably, the chlorinated polyolefin material is a polymer formed by polymerization of monomers including chlorinated olefins or an article containing such polymer. The chlorinated olefin can be as shown in formula (I);

[0068]

[0069] R1, R3, R5 and R7 are each independently selected from C1 to C6 alkylene groups or single bonds, R2, R4, R6 and R8 are each independently selected from H and Cl, and at least one of R2, R4, R6 and R8 is Cl.

[0070] In this invention, R1, R3, R5, and R7 are each independently selected from C1-C6 alkylene groups or single bonds. Preferably, R1, R3, R5, and R7 are each independently selected from C1-C3 alkylene groups or single bonds. In some embodiments, R1, R3, R5, and R7 are each independently selected from methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, sec-butylene, tert-butylene, n-pentylene, methylbutylene, dimethylpropylene, ethylpropylene, n-ethylene, methylpentylene, ethylbutylene, dimethylbutylene, and single bonds.

[0071] According to one embodiment of the present invention, R1, R3, R5, and R7 are all single bonds. When R1 is a single bond, R2 and C are directly connected by a single bond. The same applies when R3, R5, and R7 are single bonds.

[0072] In this invention, R2, R4, R6, and R8 are each independently selected from H and Cl, and at least one of R2, R4, R6, and R8 is Cl. In some embodiments, two of R2, R4, R6, and R8 are Cl. In other embodiments, one of R2, R4, R6, and R8 is Cl.

[0073] The polymer of the present invention is formed by polymerization of the monomers represented by formula (I). The polymerization is specifically an addition polymerization reaction. The polymer of the present invention may be selected from one or more of polyvinyl chloride, polyvinylidene chloride, and polytetrachloroethylene. According to one embodiment of the present invention, the polymer is polyvinyl chloride.

[0074] The articles containing the polymer of the present invention can be waste products. In the articles containing the polymer, the content of the polymer is greater than or equal to 30 wt%; preferably, greater than or equal to 40 wt%; more preferably, greater than or equal to 50 wt%; and most preferably, greater than or equal to 70 wt%.

[0075] Products containing this polymer include, but are not limited to, pipes, window frames, wires, cable insulation, infusion bags, catheters, surgical instruments, packaging bags, and packaging paper.

[0076] In this invention, the phosphorus-containing rare earth ore contains at least one of monazite and xenotime. Preferably, the phosphorus-containing rare earth ore contains monazite. More preferably, the phosphorus-containing rare earth ore is monazite. In some embodiments, the phosphorus-containing rare earth ore can be a mixed rare earth ore. In the mixed rare earth ore, the content of monazite and / or xenotime is ≥5 wt%; preferably, the content of monazite and / or xenotime is ≥10 wt%. In some embodiments, the content of monazite and / or xenotime in the mixed rare earth ore is 10-40 wt%. In addition to xenotime, the mixed rare earth ore may also contain bastnaesite. In some embodiments, the phosphorus-containing rare earth ore is a mixture of monazite and bastnaesite.

[0077] The phosphorus-containing rare earth ore is a phosphorus-containing rare earth concentrate. The rare earth element content in the phosphorus-containing rare earth ore is greater than or equal to 50 wt%; preferably, the rare earth element content in the phosphorus-containing rare earth ore is greater than or equal to 60 wt%. The mass of rare earth elements is expressed as REO.

[0078] The mass ratio of phosphorus-containing rare earth ore to chlorinated polyolefin material is 1:(4-9); preferably 1:(5-8); more preferably 1:(5-6). The mass of phosphorus-containing rare earth ore is calculated by converting the rare earth element it contains into the mass of the corresponding rare earth oxide. The mass of chlorinated polyolefin material is calculated by the mass of the polymer it contains.

[0079] Specifically, the process includes the following steps: (1) calcining a mixture comprising chlorinated polyolefin material and phosphorus-containing rare earth ore at 500–900°C to obtain a calcined product; (2) leaching the calcined product with water to obtain a rare earth solution. The calcination and leaching steps are as described above and will not be repeated here.

[0080] The test methods for this embodiment and the comparative example are described below:

[0081] (1) Decomposition rate of phosphorus-containing rare earth ores:

[0082] The decomposition rate of phosphate-containing rare earth ores is calculated using the following formula:

[0083]

[0084] Where μ represents the decomposition rate of the phosphorus-containing rare earth ore, in wt%; C represents the concentration of rare earth chlorides in the rare earth solution, calculated as REO, in g / L; V represents the volume of the rare earth solution, in L; ω represents the content of rare earth compounds in the phosphorus-containing rare earth ore, calculated as REO, in wt%; and m represents the weight of the phosphorus-containing rare earth ore, in g.

[0085] The concentration of rare earth chlorides in rare earth solutions was measured using the following method: the concentration of rare earth chlorides, expressed as REO, was determined by inductively coupled plasma mass spectrometry.

[0086] The content of rare earth compounds in phosphate-containing rare earth ores was tested using the following method: Inductively coupled plasma atomic emission spectrometry was used to determine the content of rare earth compounds in phosphate-containing rare earth ores, calculated as REO.

[0087] (2) Oxidation rate of cerium:

[0088] The rare earth solution was heated to a gentle boil in an electric furnace and maintained for 30 minutes. After cooling to room temperature, the solution was filtered. The Ce(Ⅳ) content in the filtrate was analyzed and the cerium oxidation rate was calculated.

[0089] The formula for calculating the cerium oxidation rate η is as follows:

[0090]

[0091] In the formula, η is the cerium oxidation rate, in %; C Ce4 ω represents the concentration of cerium(IV) compounds in the filtrate, calculated as REO, in g / L; V represents the volume of the filtrate, in L; ω represents the content of rare earth compounds in the monazite concentrate, calculated as REO, in wt%; m represents the mass of the monazite concentrate, in g; δ Ce The percentage of cerium in monazite concentrate, expressed as rare earth oxides, is expressed in wt%.

[0092] The raw materials for the examples and comparative examples are described below:

[0093] Waste PVC pipes: PVC content is 80wt%, and also contains 5wt% dioctyl phthalate (DOP), 5wt% calcium stearate, and 6wt% calcium carbonate.

[0094] Example 1

[0095] 200g of waste PVC pipes were crushed, and the resulting product was then mixed evenly with 50g of monazite concentrate (REO content 60.3wt%) and ground to below 400 mesh to obtain a ground product. The ground product was then mixed with 5g of slaked lime to obtain a premix.

[0096] The premix was formed into spherical blanks with a diameter of 15 mm. The spherical blanks were dried at 50 °C for 1 h to form a calcination mixture. The mixture was placed in a rotary kiln and heated to 800 °C at a heating rate of 2 °C / min, and calcined at 800 °C for 2 h to obtain the calcined product.

[0097] Water and the calcined product were mixed at a volume ratio of 4:1 and soaked at 50°C for 1.5 hours to obtain a rare earth solution. The concentration of rare earth chlorides and the oxidation rate of cerium in the rare earth solution were determined using the above test method. The calculation results are shown in Table 1.

[0098] Example 2

[0099] 200g of waste PVC pipes were crushed, and the resulting product was then mixed evenly with 30g of monazite concentrate (REO content 67.1wt%) and ground to below 400 mesh to obtain a ground product. The ground product was then mixed with 4g of hydrated lime to obtain a premix.

[0100] The premix was formed into spherical blanks with a diameter of 15 mm. The spherical blanks were dried at 50 °C for 1 h to form a calcination mixture. The mixture was placed in a rotary kiln and heated to 700 °C at a heating rate of 2 °C / min, and calcined at 700 °C for 2 h to obtain the calcined product.

[0101] Water and the calcined product were mixed at a volume ratio of 4:1 and soaked at 50°C for 1.5 hours to obtain a rare earth solution. The concentration of rare earth chlorides and the oxidation rate of cerium in the rare earth solution were determined using the above test method. The calculation results are shown in Table 1.

[0102] Example 3

[0103] 200g of waste PVC pipes were crushed, and the resulting product was then mixed evenly with 40g of monazite concentrate (REO content 53.1wt%) and ground to below 400 mesh to obtain a ground product. The ground product was then mixed with 5g of slaked lime to obtain a premix.

[0104] The premix was formed into spherical blanks with a diameter of 20 mm. The spherical blanks were dried at 50 °C for 1 h to form a calcination mixture. The mixture was placed in a rotary kiln and heated to 800 °C at a heating rate of 2 °C / min, and calcined at 800 °C for 2.5 h to obtain the calcined product.

[0105] Water and the calcined product were mixed at a volume ratio of 4:1 and soaked at 70°C for 2.5 hours to obtain a rare earth solution. The concentration of rare earth chlorides and the oxidation rate of cerium in the rare earth solution were determined using the above test method. The calculation results are shown in Table 1.

[0106] Example 4

[0107] 200g of waste PVC pipes were crushed, and the resulting product was then mixed evenly with 30g of monazite concentrate (REO content 67.1wt%) and ground to below 400 mesh to obtain a ground product. The ground product was then mixed with 3.5g of hydrated lime to obtain a premix.

[0108] The premix was formed into spherical blanks with a diameter of 20 mm. The spherical blanks were dried at 50 °C for 1 h to form a calcination mixture. The mixture was placed in a rotary kiln and heated to 800 °C at a heating rate of 2 °C / min, and calcined at 800 °C for 2 h to obtain the calcined product.

[0109] Water and the calcined product were mixed at a volume ratio of 4:1 and soaked at 60°C for 2.0 h to obtain a rare earth solution. The concentration of rare earth chlorides and the oxidation rate of cerium in the rare earth solution were determined using the above test method. The calculation results are shown in Table 1.

[0110] Example 5

[0111] 200g of waste PVC pipes were crushed, and the resulting product was then mixed evenly with 40g of monazite concentrate (REO content 53.1wt%) and ground to below 400 mesh to obtain a ground product. The ground product was then mixed with 5g of slaked lime to obtain a premix.

[0112] The premix was formed into spherical blanks with a diameter of 15 mm. The spherical blanks were dried at 70 °C for 2 h to form a calcination mixture. The mixture was placed in a rotary kiln and heated to 700 °C at a heating rate of 2 °C / min, and calcined at 700 °C for 2.5 h to obtain the calcined product.

[0113] Water and the calcined product were mixed at a volume ratio of 4:1 and soaked at 90°C for 1.0 h to obtain a rare earth solution. The concentration of rare earth chlorides and the oxidation rate of cerium in the rare earth solution were determined using the above test method. The calculation results are shown in Table 1.

[0114] Comparative Example 1

[0115] 200g of polypropylene was crushed, and the resulting product was then mixed evenly with 50g of monazite concentrate (REO content 60.3wt%). The mixture was ground to below 400 mesh to obtain a ground product. The ground product was then mixed with 5g of slaked lime to obtain a premix.

[0116] The premix was formed into spherical blanks with a diameter of 15 mm. The spherical blanks were dried at 50 °C for 1 h to form a calcination mixture. The mixture was placed in a rotary kiln and heated to 800 °C at a heating rate of 2 °C / min, and calcined at 800 °C for 2 h to obtain the calcined product.

[0117] Water and the calcined product were mixed at a volume ratio of 4:1 and soaked at 50°C for 1.5 hours to obtain a rare earth solution. The concentration of rare earth chlorides and the oxidation rate of cerium in the rare earth solution were determined using the above test method. The calculation results are shown in Table 1.

[0118] Table 1

[0119]

[0120] In Comparative Example 1, polypropylene and monazite concentrate were co-roasted. The monazite concentrate did not decompose significantly, and the solution obtained after water leaching of the roasted product contained virtually no rare earth elements. As can be seen from Examples 1-5, parameters such as the amount of raw materials, the diameter of the green body, and the temperature and time of each step can have a certain impact on the decomposition rate of monazite concentrate and the oxidation rate of cerium.

[0121] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A method for processing phosphorus-containing rare earth ore, characterized in that, The steps include the following: (1) A mixture comprising chlorinated polyolefin material, phosphorus-containing rare earth mineral and calcium hydroxide is formed into a green body and then calcined at 700-800℃ for 1-3 hours to obtain a calcined product; the diameter of the green body is 10-30 mm; Wherein, the chlorinated polyolefin material is a polymer formed by polymerization of monomers including chlorinated olefins or a product containing the polymer; the mass ratio of phosphorus-containing rare earth ore to chlorinated polyolefin material is 1:(4-9), the mass of phosphorus-containing rare earth ore is calculated by converting the rare earth elements contained therein into the mass of rare earth oxides corresponding to the rare earth elements, and the mass of chlorinated polyolefin material is calculated by the polymer contained therein. The calcium hydroxide content in the mixture is 0.1–3 wt%; The phosphorus-containing rare earth mineral is monazite. (2) The roasted product was soaked in water to obtain a rare earth solution; The decomposition rate of phosphorus-containing rare earth ores is greater than or equal to 80 wt%, and the oxidation rate of cerium is ≤1 wt%.

2. The processing method according to claim 1, characterized in that, The chlorinated olefin is as shown in formula (I): （I）； R1, R3, R5 and R7 are each independently selected from C1 to C6 alkylene groups or single bonds, R2, R4, R6 and R8 are each independently selected from H or Cl, and at least one of R2, R4, R6 and R8 is Cl.

3. The processing method according to claim 2, characterized in that, R1, R3, R5, and R7 are independently selected from methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, sec-butylene, tert-butylene, n-pentylene, methylbutylene, dimethylpropylene, ethylpropylene, methylpentylene, ethylbutylene, dimethylbutylene, and single bonds.

4. The processing method according to claim 1, characterized in that: The rare earth ore containing phosphorus contains at least 50 wt% rare earth elements, wherein the rare earth element content is expressed as REO.

5. The processing method according to claim 1, characterized in that, In step (2), water and calcined product are mixed at a volume ratio of (1-10):1 and soaked in water at 50-90°C for 0.5-3 hours.

6. The use of a chlorinated polyolefin material in the decomposition of phosphorus-containing rare earth ores, characterized in that, The steps include the following: (1) A mixture comprising chlorinated polyolefin material, phosphorus-containing rare earth mineral and calcium hydroxide is formed into a green body and then calcined at 700-800℃ for 1-3 hours to obtain a calcined product; the diameter of the green body is 10-30 mm; Wherein, the chlorinated polyolefin material is a polymer formed by polymerization of monomers including chlorinated olefins or a product containing the polymer; the mass ratio of phosphorus-containing rare earth ore to chlorinated polyolefin material is 1:(4-9), the mass of phosphorus-containing rare earth ore is calculated by converting the rare earth elements contained therein into the mass of rare earth oxides corresponding to the rare earth elements, and the mass of chlorinated polyolefin material is calculated by the polymer contained therein. The calcium hydroxide content in the mixture is 0.1–3 wt%; The phosphorus-containing rare earth mineral is monazite. (2) The roasted product was soaked in water to obtain a rare earth solution; The decomposition rate of phosphorus-containing rare earth ores is greater than or equal to 80 wt%, and the oxidation rate of cerium is ≤1 wt%.

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