AU2016279392B2

AU2016279392B2 - Method for recovering phosphorus and rare earth from rare earth-containing phosphate ore, and substance containing rare earth phosphate

Info

Publication number: AU2016279392B2
Application number: AU2016279392A
Authority: AU
Inventors: Dali Cui; Zongyu FENG; Xiaowei Huang; Zhiqi Long; Chunmei Wang; Liangshi Wang; Shengxi Wu; Yang Xu; Longsheng ZHAO
Original assignee: Grirem Advanced Materials Co Ltd
Current assignee: Grirem Advanced Materials Co Ltd
Priority date: 2015-06-19
Filing date: 2016-06-15
Publication date: 2019-01-31
Anticipated expiration: 2036-06-15
Also published as: WO2016202257A1; MY173056A; AU2016279392A1; ZA201800118B

Abstract

Provided are a method for recovering phosphorus and a rare earth from a rare earth-containing phosphate ore, and a substance containing a rare earth phosphate. The method comprises: step S1, leaching the rare earth phosphate ore by using a solution containing phosphoric acid, to obtain an acid-leached residue and a leachate; and step S2, subjecting the leachate to an ageing treatment so as to obtain a rare earth phosphate precipitate. The reaction temperature of step S2 is higher than the reaction temperature of step S1. The rare earth phosphate ore is acid leached by using a solution containing phosphoric acid at a relatively low reaction temperature, and then the leachate is subjected to an ageing treatment at a relatively high temperature, such that the rare earth ions form a rare earth phosphate precipitate, thereby achieving the efficient separation and recovery of the rare earth and phosphorus.

Description

A METHOD FOR RECOVERING PHOSPHORUS AND RARE EARTH FROM RARE EARTH-CONTAINING PHOSPHORITE AND SUBSTANCE CONTAINING RARE EARTH PHOSPHATE Technical field

The present disclosure relates to the field of rare earth recovery, in particular to a method for recovering phosphorus and rare earth from rare earth-containing phosphorite and substance containing rare earth phosphate.

Background art

Rare earth minerals usually associate with minerals including barite, calcite, apatite, silicate minerals etc. in nature. The occurrence state and content of rare earth are different in various minerals due to the difference of the mineralization processes. Generally, rare earth oxides (REO) content in current mined minerals is about several weight percents. In order to meet the rare earth grade requirement of metallurgy, it is necessary to separate rare earth from other ores by mineral dressing before extraction. Usually, the content of rare earth oxides in concentrate is required up to 50%-70%.

Major rare earth minerals include bastnaesite, monazite, xenotime and ion-adsorpted rare earth ores etc.. At present, rare earth in monazite is mainly recovered by the following two methods: (1) Alkaline digestion process (applicable to a high grade monazite ore). In this process, insoluble rare earth hydroxides are generated, phosphorus is transformed into trisodium phosphate, and the mixed rare earth chlorides is produced after hydrochloric acid selective dissolution and impurity removal. Colloidal substances including sodium silicate, ferric hydroxide etc. will be formed easily if concentrate has a relative high impurity content of silicon and iron etc.. Which makes precipitation, filtering and separation processes difficult to conduct, therefor, the process will not be able to be operated normally. (2) Sulfuri acid roast and leaching process, a monazite concentrate is mixed with concentrated sulfuric acid by 1.7 to 2 times the weight of concentrate followed by decomposition process at 200 °C to 230 °C. Then the roasted concentrate is cooled and then leached by water with a L/S = 7-10 (liquid to solid ratio, mL/g). Generally, in the leaching, the acidity is about 2.5mol/L, rare earth concentration is about 50g/L (REO), impurity concentration is about 25g/L P₂Os and 2.5g/L Fe2O₃. The leaching solution has the characteristics of highly acidiy, high content of impurities including phosphorus and thorium, rare earth and thorium are precipitated by double sulfates with sodium sulfate, then transformed into hydroxides by an alkali, subsequently, rare earth is separated from thorium by acid preferentially leaching and solvent extraction. The method is a complicated and discontinuous process that has many liquid-solid separation steps and a low rare earth recovery. Besides, both acid and alkali are used in one flowsheet, which results in large consumption of chemicals and high cost. Furthermore, the dispose of phosphorus containing wastewater and the recovery of radioactive element-thorium dispersed in slag and wastewater are two big issues.

Phosphorite is the main raw material of phosphorus chemical industry. The world reserves of phosphorite resources is huge, and phosphorite usually contains trace rare earth. At present, methods for recovering rare earth in phosphorite include the following processes: (1) hydrometallugical processes of phosphorite with hydrochloric acid , nitric acid, in which more than 95% of rare earth enters leaching solution, and then rare earth is recovered from leachin solutions by methods of solvent extraction, ion exchange, precipitation, crystallization etc.; (2) wet process of phosphorite with sulfuric acid, in which rare earth enters a solution and phosphogypsum respectively, and the phosphogypsum is then leached by sulfuric acid so that rare earth enters a solution, and the rare earth in the solution may be recovered by means of solvent extraction, ion exchange, precipitation, crystallization etc.. (3) A technique for processing phosphorite with phosphoric acid. In patent CN201110143415.0, rare earth was recovered by mixing phosphate concentrate with phosphoric acid and controlled the leaching conditions to precipitate rare earth in the form of fluorides, more than 85% of the rare earth is enters a slag. Then, rare earth in slag is dissolved by hydrochloric acid, nitric acid or sulfuric acid and recovered by further treatments. However, rare earth concent in the slag is as low as about lwt%, and high percentage of phosphorus, calcium, aluminum, silicon etc. leads to negtive effect on further rare earth recovery. Furthermore, rare earth fluorides are difficult to dissolve with acid, resulting in high acid consumption, a large amount of slag generation, and a low recovery of rare earth. Besides, 15% of rare earth in a leaching solution enters gypsum slag during the calcium removal process, and it is difficult to recovere this part of rare eath.

Rare earth-phosphorite containing monazite is a hardly dispose ore that contains monazite, rare earth, phosphorite etc.. Monazite and phosphorite are phosphate minerals that have similar mineralogical properties. In their associated minerals, monazite and phosphorite are embeded closely. Therefore, it is difficult to separate monazite from phosphorite via physical dressing. Even worse, it is impossible to completely dissolve monazite in current phosphoric acid production process with H₂SO₄ since decompostion of monazite requires a relatively high temperature and acidity.

Therefore, the recovery of rare earth and phosphorus from phosphorite has become a technical ploblem that is urgent to be solved. Especillay, for rare earth recovery from poor quality minerals with complicated compositions, such as phosphorite associated with monazite.

Summary

The main purpose of the present invention is to provide a method for recovering phosphorus and rare earth from a rare earth-containing phosphorite, so as to solve the problem of low recovery efficiency of phosphorus and rare earth elements from rare earth-containing phosphorite in the prior art.

In order to achieve the above object, according to one aspect of the present invention, there is provided a method for recovering phosphorus and rare earth from a rare earth-containing phosphorite. The method includes the following steps: step SI, leaching the rare earth-containing phosphorite by using a phosphoric acid-containing solution to obtain a leaching solution and an acid leaching slag, the leaching solution containing rare earth ions, Ca and H2PO4'; and step S2, aging the leaching solution to obtain a rare earth phosphate precipitate and a monocalcium phosphate solution; wherein, the reaction temperature of the step S2 is higher than the reaction temperature of the step S1.

Further, the step SI includes: leaching the rare earth-containing phosphorite by using a phosphoric acid-containing solution for 0.5 to 8 hours, preferably 1 to 4 hours at a temperature of 10 °C to 60 °C to obtain the leaching solution and the acid leaching slag.

Further, the step S2 includes: aging the leaching solution for 0.5 to 24 hours, preferably 1 to 8 hours at a temperature of 60 °C to 150 °C, preferably 80 °C to 120 °C to obtain the rare earth phosphates precipitate and the monocalcium phosphate solution.

Further, when the rare earth-containing phosphorite does not contain monazite and/or xenotime, the method further includes: recovering the rare earth in the rare earth phosphate precipitate; and recovering the phosphorus in the monocalcium phosphate solution.

Further, when the rare earth-containing phosphorite contains monazite and/or xenotime, the method further includes: mixing the acid leaching slag and the rare earth phosphate precipitate to obtain a rare earth mixed slag; recovering the rare earth in the rare earth mixed slag; and recovering the phosphorus in the monocalcium phosphate solution.

Further, the step of recovering the phosphorus in the monocalcium phosphate solution includes: adding a concentrated sulfuric acid with a mass concentration larger than 90% into the monocalcium phosphate solution to obtain a solid-liquid mixture; performing solid-liquid separation on the solid-liquid mixture to obtain a first phosphoric acid solution and calcium sulfate.

Further, in the step of recovering the phosphorus in the monocalcium phosphate solution, after obtaining the first phosphoric acid solution, the step further includes: returning the first phosphoric acid solution to the step SI for leaching the rare earth-containing phosphorite; or performing impurity removal on the first phosphoric acid solution to obtain a second phosphoric acid solution, and returning the second phosphoric acid solution to the step SI for leaching the rare earth-containing phosphorite.

Further, the step of recovering the rare earth elements in the rare earth mixed slag includes: step A, adding an iron-containing substance and adding concentrated sulfuric acid with a mass concentration larger than 90% to obtain a mixture; step B, roasting the mixture to obtain a roasted product; step C, leaching the roasted product by water to obtain a rare earth-containing water leaching solution and a water leaching slag; step D, adjusting the pH value of the rare earth-containing water leaching solution to 3.8 to 5, filtering and obtaining a rare earth sulfate solution and a filtered slag containing iron, phosphorus and thorium; and step E, preparing rare earth compound from the rare earth sulfate solution, wherein, the step E includes: extracting and separating the rare earth sulfate solution by using an acidic phosphorus extractant to obtain a mixed rare earth chloride or single rare earth compound; or adding a carbonate or an oxalate into the rare earth sulfate solution to precipitate the rare earth, and obtaining a rare earth carbonate or a rare earth oxalate, and calcining the rare earth carbonate or the rare earth oxalate to obtain a rare earth oxide.

Further, the iron-containing substance is an iron-containing tailing and/or an iron-containing slag.

Further, the mass ratio of the iron in the iron-containing substance to the phosphorus in the rare earth mixed slag is 2 to 4: 1, preferably 2.5 to 3.5: 1.

Further, the step A further includes mixing the concentrated sulfuric acid and the rare earth mixed slag with a mass ratio of 1 to 2: 1.

Further, in the step B, the roasting temperature is 200 °C to 500 °C, the time is 1 hour to 8 hours, preferably, the roasting temperature is 250 °C to 400 °C, the time is 2 hours to 4 hours.

Further, in the step D, the pH value of the rare earth-containing water leaching solution is adjusted to 4 to 4.5 by using at least one of magnesium oxide, magnesium hydroxide and light-burned dolomite.

Further, the phosphoric acid-containing solution further comprises hydrochloric acid and/or nitric acid.

Further, based on P₂O₅, a mass fraction of phosphoric acid in the phosphoric acid-containing solution is 15% to 50%, preferably 15% to 30%.

Further, based on a molar number of anions, a proportion of the hydrochloric acid and/or the nitric acid in the phosphoric acid-containing solution is less than 30%, preferably 2% to 15%.

Further, before the step SI, the method further includes a step of mixing the phosphoric acid-containing solution and the rare earth-containing phosphorite at a liquid-to-solid ratio of 2L to 10L: 1 kg, preferably 3L to 6L: 1 kg.

According to one aspect of the present invention, there is provided a substance containing rare earth phosphate, the rare earth phosphate in the substance containing rare earth phosphate at least contains a first phase structure and a second phase structure, the first phase structure is an amorphous phase, and the second phase structure comprises a monazite phase or/and a xenotime phase; the substance containing rare earth phosphate is separated from a phosphorite containing monazite and/or xenotime, the method for separating the substance containing rare earth phosphate from a phosphorite containing monazite and/or xenotime includes: step SI, leaching the phosphorite containing monazite and/or xenotime by using a phosphoric acid-containing solution to obtain a leaching solution and a rare earth-containing acid leaching slag, the leaching solution containing rare earth ions, calcium ions and dihydrogenphosphate ions; step S2, aging the leaching solution and performing a solid-liquid separation to obtain a rare earth phosphate precipitate and a monocalcium phosphate solution; and step S3, mixing the rare earth-containing acid leaching slag and the rare earth phosphate precipitate to obtain the substance containing rare earth phosphate; the reaction temperature of the step S2 is higher than the reaction temperature of the step S1.

Further, the amorphous phase is present in the rare earth phosphate in an amount of more than 1%, preferably 5 to 40% by weight.

Further, the weight ratio of the first phase structure to the second phase structure in the substance containing rare earth phosphate is 1: 1 to 20.

Further, the substance containing rare earth phosphate further comprises iron and/or aluminum-containing impurities, and the content of iron and/or aluminum is 1 to 50% by weight, preferably 3 to 25% by weight based on oxide.

Further, in the substance containing rare earth phosphate, the weight ratio of rare earth to iron and/or aluminum is 2 to 20: 1 based on oxide.

Further, the step SI includes: leaching the phosphorite containing monazite and/or xenotime by using the phosphoric acid-containing solution for 0.5 to 8 hours, preferably 1 to 4 hours at a temperature of 10 °C to 60 °C to obtain the leaching solution and the rare earth-containing acid leaching slag.

Further, the step S2 includes: aging the leaching solution for 0.5 to 24 hours, preferably 1 to 8 hours at a temperature of 60 °C to 150 °C, preferably 80 °C to 120 °C and performing a solid-liquid separation to obtain the rare earth phosphate precipitate and the monocalcium phosphate solution.

Further, the phosphoric acid-containing solution further comprises hydrochloric acid and/or nitric acid; preferably, based on a molar number of anions, a proportion of the hydrochloric acid and/or the nitric acid in the phosphoric acid-containing solution is less than 30%, preferably 2% to 15%.

Further, based on P2O5, a mass fraction of phosphoric acid in the phosphoric acid-containing solution is 15% to 50%, preferably 15% to 30%.

Further, before the S1, the method further includes a step of mixing the phosphoric acid-containing solution and the phosphorite containing monazite and/or xenotime at a liquid-to-solid ratio of 2L to 10L: 1 kg, preferably 3L to 6L: 1 kg.

By adopting the technical solution of the present invention, the rare earth-containing phosphorite is leached by using a phosphoric acid-containing solution at a relatively low reaction temperature, phosphorus in the phosphorite is dissolved by hydrogen ions in the phosphoric acid-containing solution to form a monocalcium phosphate solution, and rare earth elements are also dissolved into the solution to form a leaching solution containing rare earth ions, Ca²⁺ and H2PO4’; the leaching solution is further aged, which is conducive to make the rare earth elements form rare earth phosphates precipitate to separate the rare earth elements from the phosphorus element. The reaction temperature has little effect on leaching of phosphorus element during acid leaching process, while the solubility of rare earth phosphate is relatively high at lower temperature, which is beneficial to leaching of rare earth elements. Meanwhile, low temperature can effectively restrain leaching of iron, aluminum and other impurities in the phosphorite, making the leaching rate of iron and aluminum elements less than 5%, greatly reducing the burden of subsequent purification and impurity removal for phosphoric acid. Moreover, by controlling the temperature of aging treatment to be higher than the temperature of acid leaching step, the rare earth phosphate has a small solubility product at a relatively high temperature, which facilitates the precipitation of rare earth elements in leaching solution in the form of rare earth phosphates and further realizes effective separation of rare earth elements and phosphorus element. From rare earth-containing phosphorite to rare earth phosphate precipitate, the rare earth enrichment factor can reach tens of times or even hundreds of times; in rare earth phosphate precipitate, the grade of rare earth can reach more than 45%, even reach more than 55%; the yield of rare earth reaches more than 80%, even reaches more than 90%, improving the separation efficiency of rare earth, realizing the purpose of separating rare earth with low cost, and facilitating subsequent further recycle of rare earth elements. When the rare earth-containing phosphorite contains monazite, the monazite is not dissolved during the acid leaching process and remains in the slag so as to achieve the separation of rare earth elements and phosphorus element. The rare earth phosphate precipitate can be mixed with the slag containing acid generated in the acid leaching process to form rare earth mixed slag, and the rare earth mixed slag has high rare earth content, which is also convenient for subsequent further recycle of rare earth elements.

Brief description of the drawings

The drawings of the description, which constitute a part of this application, are intended to provide a further understanding of the present invention, and illustrative embodiments of the present invention and its description are intended to explain the present invention and do not constitute an undue limitation to the present invention. In the drawings:

Fig. 1 shows the flowchart of a method for recovering phosphorus and rare earth from a rare earth-containing phosphorite according to an exemplary embodiment of the present invention;

Fig. 2 shows the flowchart of a method for recovering phosphorus and rare earth from a rare earth-containing phosphorite when the rare earth-containing phosphorite further contains monazite according to another exemplary embodiment of the present invention; and

Fig. 3 shows the X-ray diffraction spectrum of a substance containing rare earth phosphate obtained according to Example 26 of the present invention.

Embodiments

It should be noted that embodiments and the features in embodiments in the application may be combined with each other without conflict. Hereinafter, the present invention will be described in detail with reference to embodiments.

In the following description, the formula of monazite is (Ln, Th) PO₄, wherein the Ln refers to at least one of rare earth elements except for promethium.

Leaching solution refers to the solution containing not only monocalcium phosphate, but also rare earth, phosphoric acid, monohydrogen phosphate, dihydrogen phosphate, or iron, aluminum and other impurities in the solution.

The grade of leaching solution refers to the ratio of content of useful elements or compounds thereof in the ore. The greater the content, the higher the grade.

As pointed out in the background art, when the rare earth-containing phosphorites, such as mixed mines containing various minerals, such as apatite and monazite and so on, are treated by existing separation methods, it is difficult to effectively separate rare earth elements and phosphorus element from such complex ores. In order to avoid the drawbacks mentioned above, in an exemplary embodiment of the present invention, there is provided a method for recovering phosphorus and rare earth from a rare earth-containing phosphorite, the method includes the following steps: step SI, leaching the rare earth-containing phosphorite by using a phosphoric acid-containing solution to obtain a leaching solution and an acid leaching slag, the leaching solution containing rare earth ions, Ca²⁺ and H2PO4’; and step S2, aging the leaching solution to obtain a rare earth phosphate precipitate and a monocalcium phosphate solution; wherein, the reaction temperature of the step S2 is higher than the reaction temperature of the step S1.

In the above method, the rare earth-containing phosphorite is leached by adopting a phosphoric acid-containing solution at a relatively low reaction temperature, phosphorus in the phosphorite is dissolved by hydrogen ions in phosphoric acid-containing solution to form a monocalcium phosphate solution, meanwhile rare earth elements are also dissolved during acid leaching process and enter into solution in the form of ions to form a leaching solution; the leaching solution is further aged, which is conducive to make rare earth elements form a rare earth phosphate precipitate to separate the rare earth elements from the phosphorus element. The reaction temperature has little effect on leaching of phosphorus element during acid leaching process, while the solubility of rare earth phosphate is relatively high at lower temperature, which is beneficial to leaching of rare earth elements. Meanwhile, low temperature can effectively restrain leaching of iron, aluminum and other impurities in the phosphorite, making the leaching rate of iron and aluminum elements less than 5%, greatly reducing the burden of subsequent purification and impurity removal for phosphoric acid. Moreover, by controlling the temperature of aging treatment to be higher than the temperature of acid leaching step, the rare earth phosphate has a small solubility product at high temperature, which facilitates the precipitation of rare earth elements in leaching solution in the form of rare earth phosphates and further realizes effective separation of rare earth elements and phosphorus element.

In the above separation method, from rare earth-containing phosphorite to rare earth phosphate precipitate, the rare earth enrichment factor can reach tens of times or even hundreds of times; in the rare earth phosphate precipitate, the grade of rare earth can reach more than 45%, even reach more than 55%; the yield of rare earth reaches more than 80%, even reaches more than 90%, improving the separation efficiency of rare earth, realizing the purpose of separating rare earth with low cost, and facilitating subsequent further recycle of rare earth elements.

In the above step SI, the purpose of leaching with a phosphoric acid-containing solution is to dissolve phosphorus element and rare earth elements in the rare earth-containing phosphorite while leaving impurity elements including iron and aluminum and so on in the slag to form an acid leaching slag. Therefore, any leaching process conditions capable of dissolving phosphorus element and rare earth elements as much as possible while keeping impurity elements including iron and aluminum and so on as much as possible in the acid leaching slag are suitable for the present invention. In a preferred embodiment of the present invention, rare earth-containing phosphorite is continuously leached with a phosphoric acid-containing solution for 0.5 to 8 hours, preferably 1 to 4 hours at a temperature of 10 °C to 60 °C to obtain a leaching solution and an acid leaching slag. The acid leaching slag can be selectively returned to phosphorus recovery process for further leaching and recovery of residual phosphorus element.

In the above step of leaching with phosphoric acid-containing solution, the reaction temperature is controlled in the range of 10 °C to 60 °C. The reaction temperature has little effect on leaching of phosphorus element in the rare earth-containing phosphorite, while the solubility of rare earth phosphate is relatively high at this temperature, which is beneficial to leaching of rare earth elements. Meanwhile, low temperature can effectively restrain leaching of iron, aluminum and other impurities in the rare earth-containing phosphorite, making the leaching rate of iron and aluminum elements less than 5%, greatly reducing the burden of subsequent impurity removal. More preferably, the leaching time is 2 to 5 hours. The leaching time in this range can not only dissolve out phosphorus element and rare earth elements compleltely, but also shorten leaching cycle.

In the above step of aging treatment, the specific time and temperature of aging treatment can be adjusted according to different type of rare earth-containing phosphorite. In a preferred embodiment of the present invention, the leaching solution is aged for 0.5 to 24 hours, preferably 1 to 8 hours at a temperature of 60 °C to 150 °C, preferably 80 °C to 120 °C and subjected to solid-liquid separation to obtain a rare earth phosphate precipitate and a second solution. The rare earth phosphate has a small solubility product at a relatively high temperature. By using the higher temperature mentioned above, rare earth elements in the leaching solution are precipitated as rare earth phosphates, so that rare earth elements and phosphorus elements can be effectively separated. As the aging time increases, the crystals gradually grow up, and amorphous precipitates gradually transform into crystalline precipitates. In the above aging time range, rare earth elements in the leaching solution can be precipitated more completely, so that the separation of rare earth elements and phosphorus element can be more effectively achieved.

In the step S2, rare earth elements are separated in the form of rare earth phosphate precipitate to obtain a monocalcium phosphate solution, wherein the main components are calcium ion and dihydrogen phosphate ion, and the impurity is a small amount of monohydrogen phosphate ion, iron or aluminum ion and so on.

The above separation method can effectively separate the rare earth phosphate precipitate and the rare earth leaching solution. From rare earth-containing phosphorite to rare earth phosphate precipitate, the rare earth enrichment factor can reach tens of times or even hundreds of times;

in the rare earth phosphate precipitate, the grade of rare earth can reach more than 45%, even reach more than 55%; the yield of rare earth reaches more than 80%, even reaches more than 90%, improving the separation efficiency of rare earth, realizing the purpose of separating rare earth with low cost, and facilitating subsequent further recycle of rare earth elements. In a preferred embodiment of the present invention, when the rare earth-containing phosphorite does not contain monazite and/or xenotime, the above method further includes: recovering the rare earth in the rare earth phosphate precipitate; and recovering the phosphorus in the monocalcium phosphate solution. Recycle of rare earth elements uses any way of acid dissolving, alkali transforming-acid dissolving, sulfuric acid roasting-water leaching, and then conducting precipitation for enrichment, or extraction for separation and purification. On the basis of above high separation efficiency, the recovery rates of rare earth elements and phosphorus element are also relatively high.

The rare earth-containing phosphorites that can be separated by the above separation method of the present invention include, but are not limited to, rare earth-containing apatite ore, phosphorite, or rare earth-containing collophanite. In a preferred embodiment of the present invention, the rare earth-containing phosphorite separated in the above separation method is a rare earth-containing phosphorite containing monazite and/or xenotime. As shown in Fig. 2, when the above rare earth-containing phosphorite contains monazite and/or xenotime, by using the above separation method for separation, the monazite and/or xenotrope are not dissolved during acid leaching while remain in the slag, can also achieve separation of rare earth elements and phosphorus element. Then, the rare earth phosphate precipitate is mixed with the acid leaching slag produced in acid leaching process to form a rare earth mixed slag. The sum of rare earth mixed slag obtained by the two-step separation has a high rare earth content (based on the rare earth mixed slag, the rare earth-containing phosphorite can achieve a rare earth yield greater than 90% and the leaching rates of Fe and Al can be less than 10% respectively; even in some more preferred embodiments, the rare earth-containing phosphorite has a rare earth yield of more than 97% and the leaching rates of Fe and Al can be less than 5%, respectively), raising rare earth separation efficiency and achieving the purpose of separating rare earth with low cost, which is also convenient for subsequent further recycle of rare earth elements.

The above rare earth-containing phosphorite containing monazite and/or xenotime is an ore that can be hardly disposed. Taking monazite as an example, monazite and phosphorite, which are phosphate minerals, have close mineralogical properties, and usually disseminate closely in an ore in which the monazite and the phosphorite coexist. Since it is difficult to dissociate each substance for they are coated and embedded in the mixed ore, it is hard to separate the ore effectively by physical dressing when the rare earth elements and the phosphorus element are recovered in such mixed ore. Especially, since strict conditions are required for decomposing the monazite, and a relatively high temperature and pH value and so on are required, the monazite cannot be fully decomposed in most cases when the monazite-containing phosphorite is disposed by a wet sulfuric acid process in the prior art, and the monazite cannot be recovered and utilized effectively. In the invention, the monazite is not dissolved in the acid leaching process and enriched in the slag, thereby realizing the separation of phosphorus and monazite. The rare earth entering into the solution is precipitated out in the form of rare earth phosphate precipitate by aging treatment, and mixed with the insoluble monazite in acid leaching process to form a rare earth mixed slag to recover rare earth together, thereby simplifying recovery step, increasing the rare earth recovery rate, and achieving the purpose of comprehensive recovery of rare earth at low cost.

After obtaining the high-grade rare earth mixed slag and the high purity monocalcium phosphate solution, those skilled in the art can decide whether or not to further recover rare earth elements in the rare earth mixed slag and phosphorus element in the monocalcium phosphate solution respectively according to actual needs, and can select appropriate recovery method in a targeted manner. In a preferred embodiment of the present invention, as shown in Fig. 2, after obtaining the rare earth mixed slag and the monocalcium phosphate solution, the method further includes: recovering the rare earth elements in the rare earth mixed slag; recovering the phosphorus element in the monocalcium phosphate solution to make full use of rare earth and phosphorus in the rare earth-containing phosphorite.

The specific recovery process for recovery rare earth elements in the rare earth mixed slag can be selected reasonably based on different use way of rare earth elements. In a preferred embodiment of the present invention, as shown in Fig. 2, the above step of recovering rare earth in the rare earth mixed slag includes: step A, adding an iron-containing substance (or adding a substance containing magnesium and/or calcium at the same time) and adding a concentrated sulfuric acid with a mass concentration larger than 90% to obtain a mixture; step B, roasting the mixture to obtain a roasted product; step C, leaching the roasted product by water to obtain a rare earth-containing water leaching solution and a water leaching slag; step D, adjusting the pH value of the rare earth-containing water leaching solution to 3.8 to 5, filtering and obtaining a rare earth sulfate solution and a filtered slag containing iron, phosphorus and thorium; and step E, preparing rare earth compound from the rare earth sulfate solution, wherein, the step E includes: extracting and separating the rare earth sulfate solution by using an acidic phosphorus extractant to obtain a mixed rare earth chloride or single rare earth compound; or adding a carbonate or an oxalate into the rare earth sulfate solution to precipitate the rare earth elements, and obtaining a rare earth carbonate or a rare earth oxalate, and calcining the rare earth carbonate or the rare earth oxalate to obtain a rare earth oxide.

In the above preferred embodiment, the rare earth in the rare earth-containing phosphorite is retained in the rare earth mixed slag, increasing the grade of rare earth in the rare earth mixed slag, greatly reducing the workload of subsequent processing. By using a unique process of adding an iron to immobilize the phosphorus, the phosphorus is immobilized in the slag to avoid loss of rare earth. If magnesium and/or calcium are added at the same time, it can immobilize fluorine and eliminate interference of phosphorus and fluorine, so as to effectively avoid loss of rare earth in the form of a rare earth phosphate precipitate or a rare earth chloride during subsequent water leaching process, and avoiding environmental pollution caused by the fluorine escaping as a hydrogen fluoride gas during roasting process. This recovery method for rare earth elements has low acid and alkaline consumption and the recovery rate of rare earth may reach above 90%; in the meanwhile, the thorium is transformed into thorium pyrophosphate immobilized in the slag, thus preventing the radioactive thorium from being dispersed in the process to cause pollution.

In the above process of recovering rare earth elements in the rare earth mixed slag, the purpose of the added substance containing magnesium and/or calcium is to keep fluorine element in the mixed slag still in the slag and to facilitate the separation of the rare earth elements. Thus, any substance containing magnesium and/or calcium that separates out rare earth elements while keeping fluorine element in the slag is suitable for use in the present invention. In a preferred embodiment of the present invention, the above substance containing magnesium and/or calcium is at least one of an oxide containing magnesium and/or calcium, a carbonate containing magnesium and/or calcium, or a mineral containing magnesium and/or calcium; preferably, the mineral containing magnesium and/or calcium is dolomite and/or magnesite; and the iron-containing substance is an iron-containing tailing and/or an iron-containing slag, preferably a tailing containing rare earth and iron. The use of ores has the advantage of abundant resources, and the use of waste can save energy and reduce emissions, turning waste into treasure.

Preferably, in the process of adding substance containing magnesium and/or calcium, the molar ratio of magnesium and/or calcium elements in the substance containing magnesium and/or calcium to fluorine element in the rare earth mixed slag is 1 to 2:2. The mixing ratio of the substance containing magnesium and/or calcium to the rare earth phosphate-containing slag in the present invention is not limited to the range above, the two are mixed according to the molar ratio of 1 to 2:2, base on the premise the advantage of reducing the amount of the substance containing magnesium and/or calcium adding, the fluoride in the ore may be formed into a magnesium/calcium fluoride and magnesium/calcium fluorophosphate solid immobilized in the slag during roasting process, thereby reducing environmental pollution caused by the escape of the fluoride as the hydrogen fluoride gas during roasting process, while avoiding loss of rare earth caused by the rare earth fluoride precipitate formed by the fluoride during impurity removal process of the solution, so as to further improve the yield of rare earth.

Preferably, in the step of adding iron-containing substance to the mixed slag, the amount of the iron-containing substance can be appropriately adjusted according to the content of phosphorus element in the rare earth mixed slag. In a preferred embodiment of the present invention, the mass ratio of iron element in the iron-containing substance to phosphorus element in the rare earth mixed slag is 2 to 4: 1, preferably 2.5 to 3.5: 1. An iron-containing rare earth tailing is added in the ranges above to perform processing, which not only improves the yield of rare earth, but also implements comprehensive utilization of rare earth in the tailing, while largely reducing operation cost; besides, the mass ratio of Fe/P may be controlled in subsequent impurity removal process with the pH value adjusted to 3.8 to 5, so as to form an iron phosphate precipitate and effectively remove the phosphorus, while excess iron may be hydrolyzed at the pH value to form a precipitate to avoid formation of a rare earth phosphate precipitate, thereby avoiding the rare earth loss.

Similarly, in the process of adding concentrated sulfuric acid to the rare earth mixed slag, the amount of concentrated sulfuric acid may be appropriately adjusted according to the mass of the mixed rare earth slag. In a preferred embodiment of the present invention, the concentrated sulfuric acid is added in a mass ratio of concentrated sulfuric acid to rare earth mixed slag of 1 to 2: 1 to obtain a mixture. The mass ratio of concentrated sulfuric acid and rare earth mixed slag controlled within the above range can control the amount of sulfuric acid effectively while improving the decomposition and leaching effect of rare earth.

In the process of roasting the mixture, the roasting temperature can be properly selected according to the type and content of rare earth elements in the mixture. In a preferred embodiment of the invention, the roasting temperature of the mixture is 200°C to 500°C, preferably 250°C to 400°C. The roasting is performed within the temperature ranges so that the thorium, the iron and the phosphoric acid are formed into a phosphate and/or a pyrophosphate precipitate immobilized in the slag without being leached. Meanwhile, the radioactive element thorium is also immobilized in the slag, thus preventing the radioactive element thorium from being dispersed in the process to cause pollution.

In the process of adjusting the pH value of the rare earth-containing water leaching solution, the pH value of the rare earth-containing water leaching solution may be adjusted to a suitable value by selecting suitable substance according to the composition and pH value of the rare earth-containing water leaching solution. In a preferred embodiment of the present invention, the pH value of the rare earth-containing water leaching solution is adjusted to 4 to 4.5 by using a magnesium oxide and/or a light-burned dolomite. The pH value of the rare earth-containing water leaching solution is adjusted by magnesium oxide and/or the light-burned dolomite to ensure that the phosphorus element may be transformed to an iron phosphate and a thorium phosphate precipitates as much as possible while the rare earth does not precipitate, thereby increasing the recovery rate of rare earth.

The specific recovery process of phosphorus element in the monocalcium phosphate solution can be properly selected according to different utilization of phosphorus element. In a preferred embodiment of the present invention, as shown in Fig. 1, the step of recovering phosphorus element comprises: adding a concentrated sulfuric acid with a mass concentration larger than 90% into the monocalcium phosphate solution to obtain a solid-liquid mixture; performing solid-liquid separation on the solid-liquid mixture to obtain a first phosphoric acid solution and calcium sulfate. The above preferred embodiment has the beneficial effect of recovering phosphorus element in the monocalcium phosphate solution in the form of first phosphoric acid solution containing phosphoric acid so as to realize the preparation of high-value weak acid by low-value strong acid.

In a more preferred embodiment of the present invention, in the step of recovering phosphorus in the monocalcium phosphate solution, after obtaining the first phosphoric acid solution, the step further includes: returning the first phosphoric acid solution to the step S1 for leaching the rare earth-containing phosphorite; or performing impurity removal on the first phosphoric acid solution to obtain a second phosphoric acid solution, and returning the second phosphoric acid solution to the step SI for leaching the rare earth-containing phosphorite, the second phosphoric acid solution can be further used for the production of phosphate fertilizer or phosphoric acid refined and other phosphorus chemical production. In the above method, the recovered impurity-containing or impurity-removed phosphoric acid solution or is used for the decomposition and leaching of the rare earth-containing phosphorite, the whole process is reasonably connected, thereby not only realizing the efficient separation of the rare earth elements and the phosphorus element, but also realizing the recycle of the phosphorus element. The impurity elements removed in the above impurity removal step include, but are not limited to, elements such as iron, silicon, aluminum, calcium, magnesium, thorium and uranium. According to the need, specific impurity removal steps can be conventional processes in the prior art.

During the above process of leaching rare earth-containing phosphorite with the phosphoric acid-containing solution, phosphoric acid is included in the phosphoric acid-containing solution, and hydrochloric acid and/or nitric acid may be added as appropriate. In a preferred embodiment of the present invention, the above-mentioned phosphoric acid-containing solution further comprises hydrochloric acid and/or nitric acid. Hydrochloric acid or nitric acid in the mixed acid solution is propitious to decompose apatite, thereby improving the leaching rate of phosphorus in the apatite. Besides, hydrochloric acid or nitric acid can provide hydrogen ions H⁺, and can reduce the content of phosphate radicals and the viscosity of the system with the same acid content, thus facilitating leaching of the phosphorus; in the meanwhile, the existence of chloride ions or nitrate ions is propitious to increase the solubility of calcium ions in a solution and decomposition of the apatite. In a more preferred embodiment of the invention, the proportion of hydrochloric acid and/or nitric acid is 0 to 30% (exclusive of 0), preferably 2 to 15%, based on the mole number of anions. The content of hydrochloric acid or nitric acid used in the present invention is not limited to the above range. The use of excessively high content of hydrochloric acid or nitric acid will simultaneously increase the solubility of rare earth phosphate in the system, making the precipitation of rare earth more difficult during the above aging treatment, leading to the rare earth cannot be enriched in rare earth phosphate precipitate, resulting in low yield of the rare earth.

In the above phosphoric acid-containing solution, the mass concentration of phosphoric acid can be properly selected according to the composition of the rare earth-containing phosphorite to be leached. In a preferred embodiment of the present invention, the mass concentration of phosphoric acid in the above phosphoric acid-containing solution is 15% to 50%, preferably 15% to 30%, based on P2O5. The mass concentration of P2O5 in the phosphoric acid-containing solution to be used in the present invention is not limited to the above range. When the mass concentration of P2O5 is within the above range, higher acidity favors the decomposition of phosphorite so as to increase the yield of phosphorus. However, excessively high phosphoric acid content leads to the problem of low mass transfer efficiency caused by high viscosity.

Prior to the above process of leaching rare earth-containing phosphorite with phosphoric acid-containing solution, the phosphoric acid-containing solution and the rare earth-containing phosphorite can be proportioned reasonably according to the concentration of phosphoric acid in the phosphoric acid-containing solution and the composition of the rare earth-containing phosphorite to make the phosphorus and rare earth elements in the rare earth-containing phosphorite are dissolved out. In a preferred embodiment of the present invention, liquid-to-solid ratio of the phosphoric acid-containing solution to the rare earth-containing phosphorite is 2 to 10 L: 1 kg, preferably 3 to 6 L: 1 kg. By controlling the amount of acid, it is conducive to make phosphorus element and calcium element generate soluble monocalcium phosphate Ca(H₂PC>4)2 and enter into solution in the case of reducing the amount of acid. The solubility of rare earth phosphate is large under high acidity condition, which is conducive to leaching rare earth in the apatite and entering into the solution, the ratio of the above range is conducive to full dissolution of phosphorus element and rare earth elements and is conducive to subsequent aging treatment, forming rare earth phosphate precipitate to enrich rare earth. When the ore also includes monazite, insoluble monazite will remain in the slag, so as to achieve effective separation and recovery of rare earth elements and phosphorus element.

In another exemplary embodiment of the present invention, there is also provided a substance containing rare earth phosphate, the rare earth phosphate in the substance containing rare earth phosphate at least contains a first phase structure and a second phase structure, the first phase structure is an amorphous phase, and the second phase structure comprises a monazite phase or/and a xenotime phase; the substance containing rare earth phosphate is separated from a phosphorite containing monazite and/or xenotime, the method for separating the substance containing rare earth phosphate from a phosphorite containing monazite and/or xenotime includes: step SI, leaching the phosphorite containing monazite and/or xenotime by using a phosphoric acid-containing solution to obtain a leaching solution and a rare earth-containing acid leaching slag, the leaching solution containing rare earth ions, calcium ions and dihydrogenphosphate ions; step S2, aging the leaching solution and performing a solid-liquid separation to obtain a rare earth phosphate precipitate and a monocalcium phosphate solution; and step S3, mixing the rare earth-containing acid leaching slag and the rare earth phosphate precipitate to obtain the substance containing rare earth phosphate; the reaction temperature of the step S2 is higher than the reaction temperature of the step S1.

The substance containing rare earth phosphate is rich in rare earth with a variety of phase structure, having high rare earth enrichment degree and high grade, easy to comprehensively recycle rare earth. In the above step of separating the substance containing rare earth phosphate from a phosphorite, the phosphorite containing monazite and/or xenotime are leached by adopting a phosphoric acid-containing solution at a relatively low reaction temperature, phosphorus in the phosphorite is dissolved by hydrogen ions in the phosphoric acid-containing solution to form a monocalcium phosphate solution, and rare earth elements are also dissolved into the solution to form a leaching solution containing rare earth ions, Ca and H2PO4'; while the monazite in acid leaching process does not dissolve but retained in the slag, to achieve separation of phosphorus element and monazite. The leaching solution is aged, which is conducive to make rare earth elements form rare earth phosphate precipitate to further separate rare earth elements from phosphorus element. The reaction temperature has little effect on leaching of phosphorus element during acid leaching process, while the solubility of rare earth phosphate is relatively high at lower temperature, which is beneficial to leaching of rare earth elements. Meanwhile, low temperature can effectively restrain leaching of iron, aluminum and other impurities in the phosphorite, making the leaching rate of iron and aluminum elements less than 5%, greatly reducing the burden of subsequent purification and impurity removal for phosphoric acid. Therefore, by controlling the temperature of aging treatment to be higher than the temperature of acid leaching step, the rare earth phosphate has a small solubility product at a relatively high temperature, which facilitates the precipitation of rare earth elements in the leaching solution in the form of rare earth phosphates and further realizes effective separation of rare earth elements and phosphorus element. From rare earth-containing phosphorite to rare earth phosphate precipitate, the rare earth enrichment factor can reach tens of times or even hundreds of times; in the rare earth phosphate precipitate, the grade of rare earth can reach more than 45%, even reach more than 55%; the yield of rare earth reaches more than 80%, even reaches more than 90%, improving separation efficiency of rare earth, realizing the purpose of separating rare earth with low cost, and facilitating subsequent further recycle of rare earth elements.

The amorphous phase in the substance containing rare earth phosphate which contains the above phase structure is a phase structure formed by rare earth phosphate precipitate, the level of its content is related with occurrence form and content of rare earth in the rare earth-containing phosphorite and the control conditions in the leaching step of rare earth-containing phosphorite. However, the level of its content is closely related to the level of grade of rare earth in the obtained substance containing rare earth phosphate, and determines the comprehensive recycle rate of rare earth. The substance containing rare earth phosphate having the above-mentioned various phase structures already has a relative high grade. In order to further improve its grade, in a preferred embodiment of the present invention, in the above substance containing rare earth phosphate, the content of amorphous phase in the rare earth phosphate is more than 1 wt%, preferably 5 to 40 wt%. When the content of amorphous phase is greater than lwt%, it is conducive to the subsequent recovery of rare earth in the substance containing rare earth phosphate. When the content of amorphous phase is 5 wt% to 40 wt%, the grade of rare earth is relatively higher, more conducive to the comprehensive recycle of rare earth elements.

In the above preferred embodiment, the substance containing rare earth phosphate has a high grade of rare earth when the amorphous phase content in the rare earth phosphate is in the above range. In order to further improve the utilization value of the substance, in a preferred embodiment of the present invention, the weight ratio of the first phase structure to the second phase structure in the substance containing rare earth phosphate is 1: 1 to 20. The weight ratio of the first phase structure to the second phase structure in the substance containing rare earth phosphate is controlled within the above range so that the substance containing rare earth phosphate has both of the above-mentioned phase structures at the same time and thus has an advantage of high rare earth grade. If the grade of rare earth in the substance containing rare earth phosphate is high, it is easy to carry out comprehensive recycle of rare earth, and the yield of rare earth is high.

In the above substance containing rare earth phosphate, impurities such as the above-mentioned element types are still inevitably contained in the separation due to the accompanying iron and/or aluminum minerals in the rare earth-containing phosphorite, and thus iron and/or aluminum impurities are also included. The content level of this part of impurities is related to the content of iron and/or aluminum accompanied with the rare earth-containing phosphorite and the control of acid leaching process. In a preferred embodiment of the present invention, the above iron and/or aluminum-containing impurities are present in the substance containing rare earth phosphate in an amount of 1 to 50% by weight, preferably 3 to 25% by weight, based on the oxide. The content of the above iron and/or aluminum-containing impurities in the substance containing rare earth phosphate is controlled in the range of 1 ~ 50wt%, obtaining a relatively high content of rare earth. The substance containing rare earth phosphate with the above impurity content has a high grade of rare earth, easy to recover rare earth, and achieving comprehensive utilization of iron and aluminum impurities.

Likewise, controlling the impurity content within the above range enables the substance containing rare earth phosphate of the present invention to have high rare earth grade. In order to further increase the rare earth grade, in a further preferred embodiment of the present invention, in the substance containing rare earth phosphate, the weight ratio of rare earth to iron and/or aluminum is 2 to 20: 1 based on oxide. Controlling the weight ratio of rare earth to iron and/or aluminum within the above range enables the substance containing rare earth phosphate of the present invention to have high rare earth content, which is favorable for subsequent treatment of recovering rare earth by sulfuric acid roasting treatment, can realize comprehensive utilization of iron and aluminum resources and enrich the iron and aluminum impurities in solid phase so as to reduce the impurity elements entering leaching solution and reduce the burden of subsequent phosphoric acid purification and impurity removal.

In the above step SI, the purpose of leaching with a phosphoric acid-containing solution is to dissolve phosphorus element and rare earth elements in the rare earth-containing phosphorite while leaving impurity elements and phosphoric acid-insoluble matter (rare earth of monazite phase in the monazite and/or rare earth of xenotime phase in the xenotime) in the slag to form an acid leaching slag containing rare earth. Therefore, any leaching process conditions capable of dissolving out phosphorus element and soluble rare earth elements in the phosphorite as much as possible are suitable for the present invention. In a preferred embodiment of the present invention, the phosphorite containing mononitrite and/or xenotite is leached with a phosphoric acid-containing solution for 0.5 to 8 hours, preferably 2 to 5 hours at a temperature of 10 °C to 60 °C to obtain the above leaching solution and the rare earth-containing acid leaching slag.

In the above leaching step using a phosphoric acid-containing solution, the reaction temperature is controlled within the range of 10 °C to 60 °C. Low temperature enables phosphorous and soluble rare earth elements in the phosphorite containing monitite and/or xenotromite to dissolve as completely as possible and can effectively restrain leaching of iron and/or aluminum and other impurities in the phosphorite, making the leaching rate of iron and/or aluminum elements less than 5%, greatly reducing the burden of subsequent impurity removal. More preferably, the leaching time is 2 to 5 hours. Selecting the range of leaching time both enables phosphorus element and soluble rare earth elements completely dissolved and can shorten leaching cycle.

In the above step of aging treatment, the specific time and temperature of aging treatment can be adjusted according to different type of rare earth-containing phosphorite. In a preferred embodiment of the present invention, the leaching solution is aged for 0.5 to 24 hours, preferably 1 to 8 hours at a temperature of 60 °C to 150 °C, preferably 80 °C to 120 °C and subjected to solid-liquid separation to obtain a rare earth phosphate precipitate and a second solution. The rare earth phosphate has a small solubility product at high temperature. By using the higher temperature mentioned above, the rare earth elements in the leaching solution are easily precipitated as rare earth phosphates, so that rare earth elements and phosphorus elements can be effectively separated. In the above aging time range, the rare earth elements in the leaching solution can be precipitated more completely, so that the separation of rare earth elements and phosphorus elements can be more effectively achieved. Thus in the obtained substance containing rare earth phosphate, the content of rare earth is relatively higher, which is more conducive to subsequent recycle of rare earth elements. It will be readily understood that the monocalcium phosphate solution here is not a 100% solution consisting of calcium ions and dihydrogenphosphate ions, but rather the solution in which the main part is monocalcium phosphate solution while containing trace amounts of monohydrogenphosphate ions, iron or aluminum and other imputies.

During the above process of leaching phosphorite containing monitite and/or xenotromite with phosphoric acid-containing solution, phosphoric acid is included in the phosphoric acid-containing solution, and hydrochloric acid and/or nitric acid may be added as appropriate. In a preferred embodiment of the present invention, the above-mentioned phosphoric acid-containing solution further comprises hydrochloric acid and/or nitric acid. The hydrochloric acid or nitric acid in the mixed acid solution is propitious to decompose apatite, thereby improving the leaching rate of phosphorus. Besides, the hydrochloric acid or the nitric acid can provide hydrogen ions H⁺, and can reduce the content of phosphate radicals and the viscosity of the system with the same acid content, thus facilitating leaching of phosphorus; in the meanwhile, the existence of chloride ions or nitrate ions is propitious to increase the solubility of calcium ions in a solution and decomposition of the apatite. In a more preferred embodiment of the invention, the proportion of hydrochloric acid and/or nitric acid is less than 30% (exclusive of 0), preferably 2 to 15%, based on the mole number of anions. The content of hydrochloric acid or nitric acid used in the present invention is not limited to the above range. The use of excessively high content of hydrochloric acid or nitric acid will simultaneously increase the solubility of rare earth phosphate in the system, making the precipitation of rare earth more difficult during the above aging treatment, leading to the rare earth cannot be enriched in rare earth phosphate precipitate, resulting in low yield of rare earth.

In the above phosphoric acid-containing solution, the mass concentration of phosphoric acid can be properly selected according to the composition of the phosphorite containing monitite and/or xenotromite to be leached. In a preferred embodiment of the present invention, the mass concentration of phosphoric acid in the above phosphoric acid-containing solution is 15% to 50%, preferably 15% to 30%, based on P2O5. The mass concentration of P₂O₅ in the phosphoric acid-containing solution to be used in the present invention is not limited to the above range. When the mass concentration of P₂O₅ is within the above range, higher acidity favors the decomposition of phosphorite so as to increase the yield of phosphorus. However, excessively high phosphoric acid content leads to the problem of low mass transfer efficiency caused by high viscosity.

Prior to the above process of leaching the phosphorite containing monitite and/or xenotromite with phosphoric acid-containing solution, the phosphoric acid-containing solution and the phosphorite can be proportioned reasonably according to the concentration of phosphoric acid in the phosphoric acid-containing solution and the composition of the phosphorite to make phosphorus and rare earth elements dissolved out. In a preferred embodiment of the present invention, the liquid-to-solid ratio of the phosphoric acid-containing solution to the phosphorite containing monitite and/or xenotromite is 2 to 10 L: 1 kg, preferably 3 to 6 L: 1 kg. By controlling the amount of acid, it is conducive to make phosphorus element and calcium element generate soluble monocalcium phosphate Ca(H₂PO₄)₂ and enter into the solution in the case of reducing the amount of acid. The solubility of rare earth phosphate is large under high acidity condition, which is conducive to leaching rare earth in the apatite and entering into the solution, the ratio of the above range is conducive to full dissolution of phosphorus element and rare earth elements and is conducive to subsequent aging treatment, forming rare earth phosphate precipitate to enrich rare earth. Insoluble monazite and/or xenotromite will remain in the slag, so as to achieve effective separation of rare earth elements and phosphorus element.

The beneficial effect of the present disclosure will be further described below in combination with specific examples.

In the following examples, the mass concentration of phosphoric acid is based on P₂Os and the amount of hydrochloric or nitric acid is based on the moles number of anions. The contents of iron, aluminum, rare earth and other elements are tested using ICP, and the leaching rate and recovery rate of each element are obtained by calculating, phosphorus is tested using GBT 1871.1-1995 method, calcium is tested using GBT 1871.4-1995 method.

Example 1

1000 g of phosphorite containing 0.05 wt% rare earth was used as a raw material, and leached by using a phosphoric acid solution with a mass concentration of 15%. The liquid-to-solid ratio of the system was controlled at 10: 1, a reaction was carried out for 1 h at 10°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and an acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 24 h at 60 °C to separate out rare earth elements in the form of rare earth phosphate precipitates, and solid-liquid separation was performed to obtain a monocalcium phosphate solution and 0.71 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of impurity Fe in the phosphorite was 3.5%, the leaching rate of impurity Al in the phosphorite was 2.5% and the leaching rate of phosphorus was 95.3%; the content of rare earth in the rare earth phosphate precipitate was 57.1%, and the recovery rate of rare earth was 81.08%.

Example 2

1000 g of phosphorite containing 0.2 wt% rare earth was used as a raw material, and leached by using a phosphoric acid solution with a mass concentration of 20%. The liquid-to-solid ratio of the system was controlled at 6: 1, a reaction was carried out for 6 h at 20°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and an acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 1 h at 60 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 3.30 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 4.1%, the leaching rate of Al in the phosphorite was 3.1% and the leaching rate of phosphorus was 96.8%; the content of rare earth in the rare earth phosphate precipitate was 52.1%, and the recovery rate of rare earth was 85.97%.

Example 3

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 1 h at 80 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 3.40 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 4.1%, the leaching rate of Al in the phosphorite was 3.1% and the leaching rate of phosphorus was 96.6%; the content of rare earth in the rare earth phosphate precipitate was 53.8%, and the recovery rate of rare earth was 91.46%.

Example 4

1000 g of phosphorite containing 0.3 wt% rare earth was used as a raw material, and leached by using a phosphoric acid solution with a mass concentration of 30%. The liquid-to-solid ratio of the system was controlled at 4: 1, a reaction was carried out for 3 h at 30°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and an acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 0.5 h at 100 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 4.98 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 4.2%, the leaching rate of Al in the phosphorite was 3.2% and the leaching rate of phosphorus was 96.5%; the content of rare earth in the rare earth phosphate precipitate was 55.3%, and the recovery rate of rare earth was 91.80%.

Example 5

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 3 h at 100 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 5.03 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 4.2%, the leaching rate of Al in the phosphorite was 3.2% and the leaching rate of phosphorus was 96.2%; the content of rare earth in the rare earth phosphate precipitate was 55.4%, and the recovery rate of rare earth was 92.89%.

Example 6

1000 g of phosphorite containing 0.5 wt% rare earth was used as a raw material, and leached by using a phosphoric acid solution with a mass concentration of 40%. The liquid-to-solid ratio of the system was controlled at 3: 1, a reaction was carried out for 4 h at 25°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and an acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 4 h at 120 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 8.10 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 4.5%, the leaching rate of Al in the phosphorite was 3.6% and the leaching rate of phosphorus was 95.8%; the content of rare earth in the rare earth phosphate precipitate was 56.3%, and the recovery rate of rare earth was 91.21 %.

Example 7

1000 g of phosphorite containing 0.5 wt% rare earth was used as a raw material, and leached by using a mixed solution of phosphoric acid solution with a mass concentration of 30% based on P₂O₅ and hydrochloric acid, the proportion of the hydrochloric acid in the mixed acids is 2% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 4: 1, a reaction was carried out for 3 h at 30°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and an acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 3 h at 120 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 8.23 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 4.7%, the leaching rate of Al in the phosphorite was 3.8% and the leaching rate of phosphorus was 97.1%; the content of rare earth in the rare earth phosphate precipitate was 56.8%, and the recovery rate of rare earth was 93.49%.

Example 8

1000 g of phosphorite containing 0.5 wt% rare earth was used as a raw material, and leached by using a mixed solution of phosphoric acid solution with a mass concentration of 30% based on P₂O₅ and nitric acid, the proportion of the nitric acid in the mixed acids is 2% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 4: 1, a reaction was carried out for 3 h at 30°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and an acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 3 h at 120 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 8.26 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 4.7%, the leaching rate of Al in the phosphorite was 3.8% and the leaching rate of phosphorus was 97.3%; the content of rare earth in the rare earth phosphate precipitate was 56.3%, and the recovery rate of rare earth was 93.01%.

Example 9

1000 g of phosphorite containing 0.5 wt% rare earth was used as a raw material, and leached by using a mixed solution of phosphoric acid solution with a mass concentration of 30% based on P2O5 and hydrochloric acid, the proportion of the hydrochloric acid in the mixed acids is 15% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 4: 1, a reaction was carried out for 3 h at 30°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and an acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 3 h at 120 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 8.38 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 4.9%, the leaching rate of Al in the phosphorite was 4.6% and the leaching rate of phosphorus was 98.5%; the content of rare earth in the rare earth phosphate precipitate was 56.8%, and the recovery rate of rare earth was 95.20%.

Example 10

1000 g of phosphorite containing 0.5 wt% rare earth was used as a raw material, and leached by using a mixed solution of phosphoric acid solution with a mass concentration of 40% based on P2O5 and hydrochloric acid, the proportion of the hydrochloric acid in the mixed acids is 25% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 3: 1, a reaction was carried out for 4 h at 25°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and an acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 4 h at 120 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 7.2 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 5.0%, the leaching rate of Al in the phosphorite was 5.0% and the leaching rate of phosphorus was 99.2%; the content of rare earth in the rare earth phosphate precipitate was 55.9%, and the recovery rate of rare earth was 80.50%.

Example 11

1000 g of phosphorite containing 1 wt% rare earth was used as a raw material, and leached by using a phosphoric acid solution with a mass concentration of 50%. The liquid-to-solid ratio of the system was controlled at 2: 1, a reaction was carried out for 0.5 h at 60°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and an acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 1 h at 130 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 16.9 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 8.0%, the leaching rate of Al in the phosphorite was 6.0% and the leaching rate of phosphorus was 95.0%; the content of rare earth in the rare earth phosphate precipitate was 47.8%, and the recovery rate of rare earth was 80.78%.

Example 12

1000 g of phosphorite containing 7.4 wt% rare earth was used as a raw material, wherein the content of monazite was 9.5 wt%, and the raw material was leached by using a phosphoric acid solution with a mass concentration of 20%. The liquid-to-solid ratio of the system was controlled at 6: 1, a reaction was carried out for 2 h at 25°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 205.0 g acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 1 h at 100 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 15.8 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 3.3%, the leaching rate of Al in the phosphorite was 3.0% and the leaching rate of phosphorus was 96.5%; the content of rare earth in the rare earth phosphate precipitate was 54.8%, and the recovery rate of rare earth was 97.80%.

Example 13

1000 g of phosphorite containing 7.4 wt% rare earth was used as a raw material, wherein the content of monazite was 9.5 wt%, and the raw material was leached by using a mixed solution of phosphoric acid solution with a mass concentration of 15% based on P₂O₅ and hydrochloric acid, the proportion of the hydrochloric acid in the mixed acids is 10% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 10: 1, a reaction was carried out for 8 h at 20°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 178.0 g acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 8 h at 70 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 16.5 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 4.4%, the leaching rate of Al in the phosphorite was 4.2% and the leaching rate of phosphorus was 98.2%; the content of rare earth in the rare earth phosphate precipitate was 52.8%, and the recovery rate of rare earth was 98.10%.

Example 14

1000 g of phosphorite containing 7.4 wt% rare earth was used as a raw material, wherein the content of monazite was 9.5 wt%, and the raw material was leached by using a mixed solution of phosphoric acid solution with a mass concentration of 15% based on P₂O₅ and hydrochloric acid, the proportion of the hydrochloric acid in the mixed acids is 25% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 8: 1, a reaction was carried out for 8 h at 20°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 154.0 g acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 12 h at 70 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 17.3 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 5.0%, the leaching rate of Al in the phosphorite was 5.0% and the leaching rate of phosphorus was 98.9%; the content of rare earth in the rare earth phosphate precipitate was 52.5%, and the recovery rate of rare earth was 97.75%.

Example 15

1000 g of phosphorite containing 9.0 wt% rare earth was used as a raw material, wherein the content of monazite was 11.9 wt%, and the raw material was leached by using a mixed solution of phosphoric acid solution with a mass concentration of 15% based on P₂O₅, nitric acid and hydrochloric acid, the proportion of the hydrochloric acid in the mixed acids is 15% and the proportion of the nitric acid in the mixed acids is 15%, based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 6: 1, a reaction was carried out for 4 h at 20°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 167.0 g acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 0.5 h at 150 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 17.5 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 4.8%, the leaching rate of Al in the phosphorite was 4.5% and the leaching rate of phosphorus was 98.6%; the content of rare earth in the rare earth phosphate precipitate was 53.5%, and the recovery rate of rare earth was 98.50%.

Example 16

1000 g of phosphorite containing 14.7 wt% rare earth was used as a raw material, wherein the content of monazite was 20.5 wt%, and the raw material was leached by using a mixed solution of phosphoric acid solution with a mass concentration of 25% based on P₂O₅ and hydrochloric acid, the proportion of the hydrochloric acid in the mixed acids is 10% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 3: 1, a reaction was carried out for 2 h at 15°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 258.0 g acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 2 h at 90 °C to separate rare earth elements from the monocalcium phosphate solution in the form of rare earth phosphate precipitates, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 16.7 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 3.8%, the leaching rate of Al in the phosphorite was 2.9% and the leaching rate of phosphorus was 98.4%; the content of rare earth in the rare earth phosphate precipitate was 55.7%, and the recovery rate of rare earth was 98.30%.

Comparative example 1

1000 g of phosphorite containing 0.3 wt% rare earth was used as a raw material, and leached by using a hydrochloric acid solution with a mass concentration of 20%. The liquid-to-solid ratio of the system was controlled at 6: 1, a reaction was carried out for 4 h at 30°C, and filtering was performed to obtain a solution containing rare earth and an acid leaching slag.

The solution containing rare earth was subjected to aging treatment for 3 h at 120 °C to separate out rare earth elements in the form of rare earth phosphate precipitates, and solid-liquid separation was performed to obtain 0.5 g rare earth phosphate precipitate.

The results of tests showed that the leaching rate of Fe in the phosphorite was 68%, the leaching rate of Al in the phosphorite was 56% and the leaching rate of phosphorus was 99.5%; the content of rare earth in the rare earth phosphate precipitate was 46.3%, and the recovery rate of rare earth was 7.72%.

Comparative example 2

1000 g of phosphorite containing 0.3 wt% rare earth was used as a raw material, and was leached by using a phosphoric acid solution with a mass concentration of 30%. The liquid-to-solid ratio of the system was controlled at 4: 1, a reaction was carried out for 3 h at 100 °C, and filtering was performed to obtain a monocalcium phosphate solution and 65.8 g acid leaching slag.

The results of tests showed that the leaching rate of Fe in the phosphorite was 54.2%, the leaching rate of Al in the phosphorite was 43.7% and the leaching rate of phosphorus was 96.7%; the recovery rate of rare earth was 96.7%.

As can be seen from the comparison of Examples 1 to 16 and Comparative Examples 1 and 2 above, the method of the present invention has higher separation efficiency for phosphorus and rare earth elements, and higher recoveries of rare earth elements and phosphorus element can be obtained. Moreover, as can be seen from Examples 1 to 11, the rare earth-containing phosphorite is leached by adopting a phosphoric acid-containing solution at a relatively low reaction temperature. The reaction temperature has little effect on leaching of phosphorus element during acid leaching process, while the solubility of rare earth phosphate is higher at relatively low temperature, which is beneficial to leaching of rare earth. Meanwhile, low temperature can effectively restrain leaching of iron, aluminum and other impurities in the phosphorite, making the leaching rate of iron and aluminum elements less than 5%, greatly reducing the burden of subsequent purification and impurity removal for phosphoric acid, improving the rare earth grade of rare earth phosphate precipitated obtained by subsequent aging process. And the hydrochloric acid or nitric acid in the mixed acid solution is propitious to decompose apatite, thereby improving the leaching rate of phosphorus and rare earth in the apatite. Further aging of the monocalcium phosphate solution containing rare earth is beneficial to the formation of rare earth phosphate precipitate from the rare earth elements in the solution, so as to realize separation of rare earth elements from phosphorus element. Moreover, the aging treatment being controlled at a high temperature is conducive to raising the rare earth yield and rare earth grade. The solubility product of rare earth phosphate is small at high temperature, help to make the rare earth elements in leaching solution precipitated in the form of rare earth phosphate, so as to achieve effective separation of rare earth elements and phosphorus element. As can be seen from Examples 12 to 16, when the rare earth-containing phosphorite contains monazite, the monazite is not dissolved during acid leaching process and enters in the slag for enrichment, thereby achieving separation of rare earth elements and phosphorus. The rare earth entering into the solution is precipitated by aging treatment in the form of rare earth phosphate precipitate, which is mixed with the insoluble monazite during acid leaching process to form rare earth mixed slag and then to recover the rare earth together, thereby simplifying recovery step, increasing the rare earth recovery rate, and achieving the purpose of comprehensive recovery of rare earth with low cost.

In addition, the inventors further mixed the acid leaching slag and the rare earth phosphate precipitate in Example 13 to obtain a rare earth mixed slag, and took 15 g to recover rare earth elements. The specific recovery steps are shown in following Examples 17 to 23.

Example 17

According to the phosphorus content in the mixed slag, an iron-containing slag was added to control the mass ratio of Fe/P to 2.5: 1, then a concentrated sulfuric acid with a mass concentration of 98% was added and mixed , the mass ratio of concentrated sulfuric acid to rare earth mixed slag was 1:1;

the mixture was roasted at 200 °C to obtain a roasted product;

the roasted product was leached by water to obtain a rare earth-containing water leaching solution and a water leaching slag;

the pH value of the rare earth-containing water leaching solution was adjusted to 4.0 with magnesium oxide, then filtered to obtain a rare earth sulfate solution and a filtered slag containing iron phosphate and thorium phosphate precipitates; in the rare earth sulfate solution, the content of Fe was 0.02 g/E, the content of P was 0.005 g/L, the content of Th was less than 0.05 mg/L, based on oxide;

an acidic phosphorus extractant was used for extracting and separating the rare earth sulfate solution to obtain a mixed rare earth chloride compound or single rare earth compound; wherein, the yield of rare earth was 92.5%.

Example 18

According to the phosphorus content in the mixed slag, an iron-containing slag was added to control the mass ratio of Fe/P to 2.5: 1, then a concentrated sulfuric acid with a mass concentration of 95% was added and mixed , the mass ratio of concentrated sulfuric acid to rare earth mixed slag was 1:1;

the mixture was roasted at 250 °C to obtain a roasted product;

the pH value of the rare earth-containing water leaching solution was adjusted to 4.0 with magnesium oxide, then filtered to obtain a rare earth sulfate solution and a filtered slag containing iron phosphate and thorium phosphate precipitates; in the rare earth sulfate solution, the content of Fe was 0.03 g / L, the content of P was 0.004 g/L, the content of Th was less than 0.05 mg/L, based on oxide;

a carbonate was added to the rare earth sulfate solution to precipitate rare earth, and a rare earth carbonate product was obtained, the rare earth recovery of entire process was 94.1%.

Example 19

According to the phosphorus content in the mixed slag, an iron-containing rare earth tailing and dolomite were added to control the mass ratio of Fe/P to 2.5: 1, the molar ratio of Mg and Ca to F in dolomite was 1: 2, then a concentrated sulfuric acid with a mass concentration of 99% was added and mixed , the mass ratio of concentrated sulfuric acid to rare earth mixed slag was 1:1;

the mixture was roasted at 500 °C to obtain a roasted product;

the pH value of the rare earth-containing water leaching solution was adjusted to 4.0 with magnesium oxide, then filtered to obtain a rare earth sulfate solution and a filtered slag containing iron phosphate and thorium phosphate precipitates; in the rare earth sulfate solution, the content of Fe was 0.05 g/L, the content of P was 0.004 g/L, the content of Th was less than 0.04 mg/L, based on oxide;

an acidic phosphorus extractant was used for extracting and separating the rare earth sulfate solution to obtain a mixed rare earth chloride compound or single rare earth compound; wherein, the yield of rare earth was 95.8%.

Example 20

According to the phosphorus content in the mixed slag, an iron-containing rare earth tailing and dolomite were added to control the mass ratio of Fe/P to 2: 1, the molar ratio of Mg and Ca to F in dolomite was 1.5: 2, then a concentrated sulfuric acid with a mass concentration of 99% was added and mixed, the mass ratio of concentrated sulfuric acid to rare earth mixed slag was 1.5: 1;

the mixture was roasted at 350 °C to obtain a roasted product;

the pH value of the rare earth-containing water leaching solution was adjusted to 4.5 with magnesium oxide, then filtered to obtain a rare earth sulfate solution and a filtered slag containing iron phosphate and thorium phosphate precipitates; in the rare earth sulfate solution, the content of Fe was 0.008 g/E, the content of P was 0.004 g/E, the content of Th was less than 0.05 mg/L, based on oxide;

wherein, the yield of rare earth in the rare earth sulfate solution was 94.2%.

Example 21

According to the phosphorus content in the mixed slag, an iron-containing rare earth tailing and dolomite were added to control the mass ratio of Fe/P to 4: 1, the molar ratio of Mg and Ca to F in dolomite was 1.5: 2, then the concentrated sulfuric acid with a mass concentration of 99% was added and mixed, the mass ratio of concentrated sulfuric acid to rare earth mixed slag was 1.5: 1;

the mixture was roasted at 350 °C to obtain a roasted product;

the pH value of the rare earth-containing water leaching solution was adjusted to 4.5 with light-burned dolomite, then filtered to obtain a rare earth sulfate solution and a filtered slag containing iron phosphate and thorium phosphate precipitates; in the rare earth sulfate solution, the content of Fe was 0.01 g/L, the content of P was 0.007 g/L, the content of Th was less than 0.04 mg/L, based on oxide;

wherein, the yield of rare earth in the rare earth sulfate solution was 97.3%.

Example 22

According to the phosphorus content in the mixed slag, an iron-containing rare earth tailing and dolomite were added to control the mass ratio of Fe/P to 3.5: 1, the molar ratio of Mg and Ca to F in dolomite was 1: 1, then the concentrated sulfuric acid with a mass concentration of 99% was added and mixed, the mass ratio of concentrated sulfuric acid to rare earth mixed slag was 2:1;

the mixture was roasted at 400 °C to obtain a roasted product;

the pH value of the rare earth-containing water leaching solution was adjusted to 3.8 with magnesium hydroxide, then filtered to obtain a rare earth sulfate solution and a filtered slag containing iron phosphate and thorium phosphate precipitates; in the rare earth sulfate solution, the content of Fe was 0.04 g/L, the content of P was 0.002 g/L, the content of Th was less than 0.05 mg/L, based on oxide;

wherein, the yield of rare earth in the rare earth sulfate solution was 97.5%.

Example 23

According to the phosphorus content in the mixed slag, an iron-containing slag and dolomite were added to control the mass ratio of Fe/P to 3: 1, the molar ratio of Mg and Ca to F in dolomite was 1.5: 2, then the concentrated sulfuric acid with a mass concentration of 99% was added and mixed, the mass ratio of concentrated sulfuric acid to rare earth mixed slag was 1.5: 1;

the mixture was roasted at 450 °C to obtain a roasted product;

wherein, the yield of rare earth in the rare earth sulfate solution was 96.1%.

It should be noted that the detection methods of phase structure and its content in the following Examples 24 to 32 are determined by X-ray diffraction (XRD), and the detection method of element contents is obtained by ICP or XRF method. The peak patterns of the XRD spectrums in the following Examples are very similar, as shown in the peak pattern of Example 26 shown in Fig. 3.

Example 24

1000 g of phosphorite containing 23 wt% monazite (wherein the sum content of rare earth was 16.4 wt%) was used as a raw material, and leached by using a phosphoric acid solution with a mass concentration of 15% based on P2O5. The liquid-to-solid ratio of the system was controlled at 10: 1, a reaction was carried out for 8 h at 10°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 330 g rare earth-containing acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 24 h a temperature of 60 °C to separate rare earth element from the monocalcium phosphate solution in the form of rare earth phosphate precipitate, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 13.6 g rare earth phosphate precipitate.

The acid leaching slag and rare earth phosphate precipitate were mixed to obtain a substance containing rare earth phosphate.

The results of tests showed that the substance containing rare earth phosphate had an amorphous phase content of 4.27 wt%, a content of impurities including iron and aluminum (based on oxide) of 9.2 wt%, a weight ratio of first phase structure to second phase structure of 0.045, a weight ratio of rare earth to impurities including iron and aluminum (based on oxide) of 5.04.

Example 25

1000 g of phosphorite containing 15 wt% monazite (wherein the sum content of rare earth was 11.1 wt%) was used as a raw material, and leached by using mixed acids solution of phosphoric acid and hydrochloric acid, wherein the mass concentration of phosphoric acid in the mixed acids is 50% based on P2O5, and the proportion of the hydrochloric acid in the mixed acids solution is 2% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 2: 1, a reaction was carried out for 5 h at 60°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 267 g acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 0.5 h at 150 °C to separate rare earth element from the monocalcium phosphate solution in the form of rare earth phosphate precipitate, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 18.9 g rare earth phosphate precipitate.

The rare earth-containing acid leaching slag and rare earth phosphate precipitate were mixed to obtain a substance containing rare earth phosphate.

The results of tests showed that the substance containing rare earth phosphate had a content of impurities including iron and aluminum (based on oxide) of 1.9 wt%, an amorphous phase content of 8.82 wt%, a weight ratio of first phase structure to second phase structure of 0.097, a weight ratio of rare earth to impurities including iron and aluminum (based on oxide) of 19.73.

Example 26

1000 g of phosphorite containing 9.5 wt% monazite (wherein the sum content of rare earth was 7.4 wt%) was used as a raw material, and leached by using mixed acids solution of phosphoric acid and hydrochloric acid, wherein the mass concentration of phosphoric acid in the mixed acids is 30% based on P2O5, and the proportion of the hydrochloric acid in the mixed acids solution is 25% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 8: 1, a reaction was carried out for 1 h at 20°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 205 g acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 8 h a temperature of 80 °C to separate rare earth element from the monocalcium phosphate solution in the form of rare earth phosphate precipitate, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 15.6 g rare earth phosphate precipitate.

The XRD spectrum of the substance containing rare earth phosphate of this Example is shown in Fig. 3. It can be calculated from Fig. 3 that the substance containing rare earth phosphate had a content of impurities including iron and aluminum (based on oxide) of 5.2 wt%, an amorphous phase content of 10.92 wt%, a weight ratio of first phase structure to second phase structure of 0.123, a weight ratio of rare earth to impurities including iron and aluminum (based on oxide) of 6.23.

Example 27

1000 g of phosphorite containing 28 wt% monazite (wherein the sum content of rare earth was 19.8 wt%) was used as a raw material, and leached by using mixed acids solution of phosphoric acid, hydrochloric acid and nitric acid, wherein the mass concentration of phosphoric acid in the mixed acids is 15% based on P2O5, and the proportion of the hydrochloric acid and nitric acid in the mixed acids solution is 15% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 6: 1, a reaction was carried out for 4 h at 20°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 375 g acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 1 h a temperature of 100 °C to separate rare earth element from the monocalcium phosphate solution in the form of rare earth phosphate precipitate, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 21.7 g rare earth phosphate precipitate.

The results of tests showed that the substance containing rare earth phosphate had a content of impurities including iron and aluminum (based on oxide) of 23 wt%, an amorphous phase content of 5.66 wt%, a weight ratio of first phase structure to second phase structure of 0.060, a weight ratio of rare earth to impurities including iron and aluminum (based on oxide) of 2.10.

Example 28

1000 g of phosphorite containing 35.0 wt% monazite (wherein the sum content of rare earth was 24.5 wt%) was used as a raw material, and leached by using a mixed acid solution of phosphoric acid and hydrochloric acid, wherein the mass concentration of phosphoric acid in the mixed acids is 25% based on P2O5, and the proportion of the hydrochloric acid in the mixed acids solution is 20% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 2: 1, a reaction was carried out for 0.5 h at 15°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 463 g acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 2 h a temperature of 75 °C to separate rare earth element from the monocalcium phosphate solution in the form of rare earth phosphate precipitate, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 19.3 g rare earth phosphate precipitate.

The results of tests showed that the substance containing rare earth phosphate had a content of impurities including iron and aluminum (based on oxide) of 23 wt%, an amorphous phase content of 4.07 wt%, a weight ratio of first phase structure to second phase structure of 0.042.

Example 29

1000 g of phosphorite containing 3.5 wt% monazite (wherein the sum content of rare earth was 3.3 wt%) was used as a raw material, and leached by using a mixed acid solution of phosphoric acid and hydrochloric acid, wherein the mass concentration of phosphoric acid in the mixed acids is 25% based on P₂O₅, and the proportion of the hydrochloric acid in the mixed acids solution is 10% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 3: 1, a reaction was carried out for 2 h at 15°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 143 g acid leaching slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 2 h a temperature of 120 °C to separate rare earth element from the monocalcium phosphate solution in the form of rare earth phosphate precipitate, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 18.6 g rare earth phosphate precipitate.

The results of tests showed that the substance containing rare earth phosphate had a content of impurities including iron and aluminum (based on oxide) of 5.8 wt%, an amorphous phase content of 28.66 wt%, a weight ratio of first phase structure to second phase structure of 0.402, a weight ratio of rare earth to impurities including iron and aluminum (based on oxide) of 3.46.

Example 30

1000 g of phosphorite containing 2.0 wt% monazite (wherein the sum content of rare earth was 2.3 wt%) was used as a raw material, and leached by using a mixed acid solution of phosphoric acid and hydrochloric acid, wherein the mass concentration of phosphoric acid in the mixed acids is 30% based on P₂O₅, and the proportion of the hydrochloric acid in the mixed acids solution is 25% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 6: 1, a reaction was carried out for 2 h at 15°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 124 g rare earth phosphate-containing slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 2 h a temperature of 120 °C to separate rare earth element from the monocalcium phosphate solution in the form of rare earth phosphate precipitate, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 22.5 g rare earth phosphate precipitate.

The results of tests showed that the substance containing rare earth phosphate had a content of impurities including iron and aluminum (based on oxide) of 5.6 wt%, an amorphous phase content of 49.56 wt%, a weight ratio of first phase structure to second phase structure of 0.983, a weight ratio of rare earth to impurities including iron and aluminum (based on oxide) of 2.77.

Example 31

1000 g of phosphorite containing 35 wt% monazite (wherein the sum content of rare earth was 24.5 wt%) was used as a raw material, and leached by using a mixed acid solution of phosphoric acid and hydrochloric acid, wherein the mass concentration of phosphoric acid in the mixed acids is 25% based on P₂O₅, and the proportion of the hydrochloric acid in the mixed acids solution is 10% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 3: 1, a reaction was carried out for 10 h at 90°C, and filtering was performed to obtain a monocalcium phosphate solution and 483 g rare earth phosphate-containing slag.

The results of tests showed that the rare earth phosphate-containing slag had a content of impurities including iron and aluminum (based on oxide) of 31 wt%, an amorphous phase content of 3.6 wt%, a weight ratio of first phase structure to second phase structure of 0.037, a weight ratio of rare earth to impurities including iron and aluminum (based on oxide) of2.20.

Example 32

1000 g of phosphorite containing 3.5 wt% monazite (wherein the sum content of rare earth was 3.3 wt%) was used as a raw material, and leached by using a mixed acid solution of phosphoric acid and hydrochloric acid, wherein the mass concentration of phosphoric acid in the mixed acids is 10% based on P₂O₅, and the proportion of the hydrochloric acid in the mixed acids solution is 30% based on the mole number of anions. The liquid-to-solid ratio of the system was controlled at 3: 1, a reaction was carried out for 2 h at 5°C, and filtering was performed to obtain a monocalcium phosphate solution containing rare earth and 123 g rare earth phosphate-containing slag.

The monocalcium phosphate solution containing rare earth was subjected to aging treatment for 2 h a temperature of 55 °C to separate rare earth element from the monocalcium phosphate solution in the form of rare earth phosphate precipitate, thus solid-liquid separation was performed to obtain a monocalcium phosphate solution and 2.4 g rare earth phosphate precipitate.

The results of tests showed that the substance containing rare earth phosphate had a content of impurities including iron and aluminum (based on oxide) of 1.3 wt%, an amorphous phase content of 3.7 wt%, a weight ratio of first phase structure to second phase structure of 0.038, a weight ratio of rare earth to impurities including iron and aluminum (based on oxide) of 19.90.

In the above Examples 24 to 32, the content of the amorphous phase in the rare earth phosphate is 5 to 40 wt% according to the occurrence form and content of rare earth in rare earth-containing phosphorite and the process control of leaching rare earth-containing phosphorite, more conducive to the subsequent recovery of rare earth in substance containing rare earth phosphate; the content of impurities including iron and aluminum in the above-mentioned substance containing rare earth phosphate is controlled in the range of 3 ~ 25wt%, so as to make the content of rare earth relatively higher and convenient for rare earth recovery, the impurity is enriched in solid phase to reduce the impurity elements entering into leaching solution, so as to reduce the burden of subsequent purification and impurity removal for phosphoric acid, and the presence of iron and aluminum in the substance containing rare earth phosphate is conducive to fix phosphorous during the subsequent recovery process of rare earth, which in turn is conducive to raising the yield of rare earth and to achieve the comprehensive utilization of iron and aluminum.

The rare earth elements in the substance containing rare earth phosphate obtained in the above Examples 24 to 32 can be further recycled, the specific recycling steps are shown in Fig. 1. Iron-containing material or both calcium and magnesium-containing material is added to the substance containing rare earth phosphate, and a concentrated sulfuric acid with a mass concentration greater than 90% is added for acidification and then a roasting is performed, and then the roasted product is leached with water to obtain a rare earth-containing water leaching solution and a water leaching slag; the pH value of the rare earth-containing water leaching solution is adjusted to 3.8 to 5, and filtering is performed to obtain a rare earth sulfate solution and a filtered slag, wherein the filtered slag contains iron element, phosphorus element and thorium element; finally an acidic phosphorus extractant is used to extract and separate the rare earth sulfate solution to obtain mixed or single rare earth chloride; or carbonate or oxalate is added to the rare earth sulfate solution for precipitating rare earth to obtain rare earth carbonate or rare earth oxalate; the rare earth carbonate or rare earth oxalate is subjected to further roasting to obtain rare earth oxide.

Similarly, the monocalcium phosphate solution obtained in Examples 24 to 32 is treated with sulfuric acid to obtain calcium sulfate and phosphorus-containing solution. Calcium sulfate can be used to prepare commercially available gypsum product. The phosphorus-containing solution can be further purified to remove impurities to phosphoric acid solution which can be used in step of acid leaching phosphorite, so as to achieve recycle of materials.

It can be seen from the above description that the above Examples of the present application achieves the following technical effects: the rare earth-containing phosphorite is leached by adopting a phosphoric acid-containing solution, phosphorus in the phosphorite is dissolved by hydrogen ions in the phosphoric acid-containing solution to form monocalcium phosphate, and the rare earth elements are also dissolved into the solution to form a leaching solution containing rare earth ions, Ca and EfPOf; the leaching solution is further aged, which is conducive to make the rare earth elements form rare earth phosphate precipitate to separate the rare earth elements from the phosphorus element. Moreover, the temperature of the aging treatment is controlled to be higher than the temperature of the acid leaching step. Low temperature can effectively restrain the leaching of iron, aluminum and other impurities in the rare earth-containing phosphorite, making the leaching rate of iron and aluminum elements less than 5%, greatly reducing the burden of subsequent purification and impurity removal for phosphoric acid. The rare earth phosphate has a small solubility product at a relatively high temperature, which facilitates the precipitation of rare earth elements soluble in leaching solution in the form of rare earth phosphate and further realizes effective separation of rare earth elements and phosphorus element. When the rare earth-containing phosphorite contains monazite, the monazite is not dissolved during the acid leaching process and remains in the slag, so achieving the separation of rare earth elements and phosphorus element. The rare earth phosphate precipitate can be mixed with the slag containing rare earth generated in acid leaching process to form rare earth mixed slag. The above separation method improves the separation efficiency of rare earth, makes the rare earth phosphate precipitate and the rare earth mixed slag have high content of rare earth, and realizes the purpose of separating the rare earths at a low cost so as to facilitate subsequent further recycle of rare earth elements.

The examples described above are only preferred examples of the present invention and is not intended to limit the present invention, and various changes and modifications may be made by one skilled in the art. Any modifications, equivalent substitutions, improvements and the like within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A method for recovering phosphorus and rare earth from a rare earth-containing phosphorite, characterized in that the method includes the following steps:

step SI, leaching the rare earth-containing phosphorite by using a phosphoric acid-containing solution to obtain a leaching solution and an 2_|_ acid leaching slag, the leaching solution containing rare earth ions, Ca and H2PO4'; and step S2, aging the leaching solution to obtain a rare earth phosphate precipitate and a monocalcium phosphate solution; wherein, the reaction temperature of the step S2 is higher than the reaction temperature of the step S1.

2. The method according to claim 1, characterized in that the step SI includes:

leaching the rare earth-containing phosphorite by using a phosphoric acid-containing solution for 0.5 to 8 hours, preferably 1 to 4 hours at a temperature of 10 °C to 60 °C to obtain the leaching solution and the acid leaching slag.

3. The method according to claim 1 or 2, characterized in that the step S2 includes:

aging the leaching solution for 0.5 to 24 hours, preferably 1 to 8 hours at a temperature of 60 °C to 150 °C, preferably 80 °C to 120 °C to obtain the rare earth phosphate precipitate and the monocalcium phosphate solution.

4. The method according to claim 1, characterized in that when the rare earth-containing phosphorite does not contain monazite and/or xenotime, the method further includes:

recovering the rare earth from the rare earth phosphate precipitate; and recovering the phosphorus from the monocalcium phosphate solution.

5. The method according to claim 1, characterized in that when the rare earth-containing phosphorite contains monazite and/or xenotime, the method further includes:

mixing the acid leaching slag and the rare earth phosphate precipitate to obtain a rare earth mixed slag;

recovering the rare earth from the rare earth mixed slag; and recovering the phosphorus from the monocalcium phosphate solution.

6. The method according to claim 4 or 5, characterized in that the step of recovering the phosphorus in the monocalcium phosphate solution includes:

adding a concentrated sulfuric acid with a mass concentration larger than 90% into the monocalcium phosphate solution to obtain a solid-liquid mixture;

performing solid-liquid separation on the solid-liquid mixture to obtain a first phosphoric acid solution and calcium sulfate.

7. The method according to claim 6, characterized in that in the step of recovering the phosphorus in the monocalcium phosphate solution, after obtaining the first phosphoric acid solution, the step further includes:

returning the first phosphoric acid solution to the step SI for leaching the rare earth-containing phosphorite; or performing impurity removal on the first phosphoric acid solution to obtain a second phosphoric acid solution, and returning the second phosphoric acid solution to the step SI for leaching the rare earth-containing phosphorite.

8. The method according to claim 5, characterized in that the step of recovering the rare earth elements in the rare earth mixed slag includes:

step A, adding an iron-containing substance and adding concentrated sulfuric acid with a mass concentration larger than 90% to obtain a mixture;

step B, roasting the mixture to obtain a roasted product;

step C, leaching the roasted product by water to obtain a rare earth-containing water leaching solution and a water leaching slag;

step D, adjusting the pH value of the rare earth-containing water leaching solution to 3.8 to 5, filtering and obtaining a rare earth sulfate solution and a filtered slag containing iron, phosphorus and thorium; and step E, preparing rare earth compound from the rare earth sulfate solution, wherein, the step E includes:

extracting and separating the rare earth sulfate solution by using an acidic phosphorus extractant to obtain a mixed rare earth chloride or single rare earth compound; or adding a carbonate or an oxalate into the rare earth sulfate solution to precipitate the rare earth elements, and obtaining a rare earth carbonate or a rare earth oxalate, and calcining the rare earth carbonate or the rare earth oxalate to obtain a rare earth oxide.

9. The method according to claim 1, characterized in that the phosphoric acid-containing solution further comprises hydrochloric acid and/or nitric acid.

10. The method according to claim 1 or 9, characterized in that based on P₂O₅, a mass fraction of phosphoric acid in the phosphoric acid-containing solution is 15% to 50%, preferably 15% to 30%.

11. The method according to claim 9, characterized in that based on a molar number of anions, a proportion of the hydrochloric acid and/or the nitric acid in the phosphoric acid-containing solution is less than 30%, preferably 2% to 15%.

12. The method according to claim 1, characterized in that before the step SI, the method further includes a step of mixing the phosphoric acid-containing solution and the rare earth-containing phosphorite at a liquid-to-solid ratio of 2L to 10L: 1 kg, preferably 3L to 6L: 1 kg.

13. A substance containing rare earth phosphate, characterized in that the rare earth phosphate in the substance containing rare earth phosphate at least contains a first phase structure and a second phase structure, the first phase structure is an amorphous phase, and the second phase structure comprises a monazite phase or/and a xenotime phase; the substance containing rare earth phosphate is separated from a phosphorite containing monazite and/or xenotime, the method for separating the substance containing rare earth phosphate from a phosphorite containing monazite and/or xenotime includes:

step SI, leaching the phosphorite containing monazite and/or xenotime by using a phosphoric acid-containing solution to obtain a leaching solution and a rare earth-containing acid leaching slag, the leaching solution containing rare earth ions, calcium ions and dihydrogenphosphate ions;

step S2, aging the leaching solution and performing a solid-liquid separation to obtain a rare earth phosphate precipitate and a monocalcium phosphate solution; and step S3, mixing the rare earth-containing acid leaching slag and the rare earth phosphate precipitate to obtain the substance containing rare earth phosphate;

the reaction temperature of the step S2 is higher than the reaction temperature of the step S1.

14. The substance containing rare earth phosphate according to claim 13, characterized in that the amorphous phase is present in the rare earth phosphate in an amount of more than 1%, preferably 5 to 40% by weight.

15. The substance containing rare earth phosphate according to claim 13, characterized in that the weight ratio of the first phase structure to the second phase structure in the substance containing rare earth phosphate is 1: 1 to 20.

16. The substance containing rare earth phosphate according to claim 13, characterized in that the substance containing rare earth phosphate further comprises iron and/or aluminum-containing impurities, and the content of iron and/or aluminum is 1 to 50% by weight, preferably 3 to 25% by weight based on oxide.

17. The substance containing rare earth phosphate according to claim 13, characterized in that in the substance containing rare earth phosphate, the weight ratio of rare earth to iron and/or aluminum is 2 to 20: 1 based on oxide.

18. The substance containing rare earth phosphate according to claim 13, characterized in that the step SI includes:

leaching the phosphorite containing monazite and/or xenotime by using the phosphoric acid-containing solution for 0.5 to 8 hours, preferably 1 to 4 hours at a temperature of 10 °C to 60 °C to obtain the leaching solution and the rare earth-containing acid leaching slag.

19. The substance containing rare earth phosphate according to claim 13, characterized in that the step S2 includes:

aging the leaching solution for 0.5 to 24 hours, preferably 1 to 8 hours at a temperature of 60 °C to 150 °C, preferably 80 °C to 120 °C and performing a solid-liquid separation to obtain the rare earth phosphate precipitate and the monocalcium phosphate solution.

20. The substance containing rare earth phosphate according to claim 14, characterized in that the phosphoric acid-containing solution further comprises hydrochloric acid and/or nitric acid; preferably, based on a molar number of anions, a proportion of the hydrochloric acid and/or the nitric acid in the phosphoric acid-containing solution is less than 30%, preferably 2% to 15%.

21. The substance containing rare earth phosphate according to any one of claims 18-20, characterized in that based on P₂O₅, a mass fraction of phosphoric acid in the phosphoric acid-containing solution is 15% to 50%, preferably 15% to 30%; a step of mixing the phosphoric acid-containing solution and the phosphorite containing monazite and/or xenotime at a liquid-to-solid ratio of 2L to 10L: 1 kg, preferably 3L to 6L: 1kg.