CN103184356B

CN103184356B - Treatment method for rare earth phosphate rock and enrichment method for rare earth

Info

Publication number: CN103184356B
Application number: CN201110448100.7A
Authority: CN
Inventors: 王良士; 黄小卫; 龙志奇; 于瀛; 赵娜; 李明来; 李红卫
Original assignee: Grirem Advanced Materials Co Ltd
Current assignee: Grirem Advanced Materials Co Ltd
Priority date: 2011-12-28
Filing date: 2011-12-28
Publication date: 2014-12-17
Anticipated expiration: 2031-12-28
Also published as: CN103184356A

Abstract

The invention discloses a treatment method for a rare earth phosphate rock and an enrichment method for rare earth. The treatment method comprises the following steps: mixing the rare earth phosphate rock and phosphoric acid to form mixed slurry; adding concentrated sulfuric acid into the mixed slurry in such a manner that the concentration of Ca<2+> in the mixed slurry is decreased from at least 1 wt% to the equilibrium concentration of Ca<2+> and SO4<2->, then the concentration of SO4<2-> in the mixed slurry is increased from the equilibrium concentration of Ca<2+> and SO4<2-> to at least 2 wt% and the mixed slurry is added during addition of the concentrated sulfuric acid to allow the rare earth phosphate rock to be dissolved so as to obtain hemihydrate gypsum; and subjecting the obtained hemihydrate gypsum to recrystallization to obtain dihydrate gypsum. The enrichment method for rare earth comprises a step of recovering rare earth elements from liquid obtained after recrystallization of the hemihydrate gypsum and/or liquid obtained after heating of the mixed slurry. In the process of generation of the hemihydrate gypsum, the addition speed of the concentrated sulfuric acid is controlled, and SO4<2-> in the mixed slurry is allowed to be insufficient at first and then controlled to be excess, which aids rare earth in entering into the phosphoric acid.

Description

Rare earth phosphorite treatment method and rare earth enrichment method

Technical Field

The invention relates to an ore treatment method, in particular to a rare earth phosphorite treatment method and a rare earth enrichment method.

Background

Besides various rare earth minerals, a considerable part of the natural rare earth coexists with apatite and phosphorite minerals. The ionic radius (0.848-0.106 nm) of rare earth and Ca²⁺(0.106nm) is very close, in the phosphorite, the rare earth is existed in the phosphorite in the form of homogeneous image, and along with P in the phosphorite₂O₅The grade is increased, the content of the rare earth elements is increased, and the grade and the content of the rare earth elements are in positive growth and negative growth relation.

In the prior art, the methods for recovering rare earth from phosphorite are mainly divided into wet method and thermal method. In the wet method, the method can be classified into a nitric acid method, a hydrochloric acid method and a sulfuric acid method according to the difference of the decomposition acid. The yield of comprehensively recovering rare earth by the nitric acid method is up to more than 85 percent, but the nitric acid method is mainly suitable for treating high-quality phosphorite. With the continuous reduction of high-quality phosphorite resources, the mineral types become more complex, and the application range of the nitric acid method is greatly limited.

The sulfuric acid method is characterized in that a product phosphoric acid obtained after the decomposition of the ore is a liquid phase, a byproduct calcium sulfate is a solid phase with very low solubility, the separation of the two is simple liquid-solid separation, the whole production flow is shorter than that of a nitric acid method and a hydrochloric acid method, and the method has incomparable superiority with other technological methods; in addition, the process can be used for the treatment of impurity content and P in ore₂O₅The method has low requirements on content and the like, has good universality, has economic advantages in the treatment of low-quality phosphorite, and is the mainstream method for treating the phosphorite by a wet method at present.

In the process of treating phosphorite by a sulfuric acid method, rare earth elements in the phosphorite respectively enter phosphoric acid solution and phosphogypsum, the proportion of the rare earth elements in the phosphorite is changed under the influence of the conditions of the leaching process, and the subsequent treatment process is used for enriching and recovering rare earth from the phosphoric acid solution or enriching and recovering rare earth from the phosphogypsum respectively. However, although technically feasible, the process flow is complex and economically infeasible to enrich rare earths from phosphogypsum. Therefore, the trend of comprehensively recovering rare earth in the process of treating phosphorite by using sulfuric acid wet-process phosphoric acid is to adopt various technical means to make rare earth elements enter phosphoric acid and then enrich and recover rare earth from the phosphoric acid solution.

In fact, however, in the prior art, the rare earth phosphate is very easy to enter the phosphogypsum due to eutectic and adsorption effects, so that the rare earth is mainly enriched into the phosphogypsum. In the process of wet processing of phosphate ore sulfuric acid, the enrichment proportion of rare earth in phosphogypsum and phosphoric acid is different due to different raw materials and specific processes, but the rare earth enters the phosphogypsum as the main material. For example, south africa treated Phalaborwa apatite using the sulfuric acid process found that 85% of the rare earth oxides entered phosphogypsum; when Poland is used for processing Russian Cola phosphate rock, about 70% of rare earth enters phosphogypsum in a dihydrate method, and almost all rare earth elements enter the phosphogypsum in a semi-hydrate method. Aiming at the problem, technical means such as adding a surfactant, optimizing a process and the like are provided, the crystal form of the phosphogypsum is improved, the eutectic and adsorption effects on rare earth are reduced, and the enrichment degree of the rare earth in phosphoric acid is improved (Z L200710178377.6).

However, with the continuous development and utilization of phosphate rock resources, the use of phosphorus in the world is currently shifting to low-quality phosphate rock, and the mineral types are not single minerals such as apatite and phosphorite, but are mixed minerals of multiple minerals such as apatite and monazite. Monazite, English name is Monazite, molecular formula is (Ln, Th) PO₄Wherein Ln refers to at least one of rare earth elements other than promethium. Because relatively harsh conditions are needed for decomposing monazite, higher temperature and pH value are needed, and the like, when the phosphorite containing monazite is treated by adopting a sulfuric acid method wet method in the prior art, the enrichment degree of rare earth in phosphoric acid can not be improved while the monazite is completely decomposed, and the recovery of rare earth elements in subsequent processes is not facilitated. In addition, the effective separation of rare earth independent minerals and phosphorite is difficult to realize in the ore dressing process.

In a word, the technical and economic problems still exist for the recovery of trace rare earth elements in complex rare earth phosphorite at present.

Disclosure of Invention

The invention aims at the characteristics of complex rare earth phosphorite minerals, difficult treatment, low rare earth content in the minerals and the like, abandons a method for recovering rare earth at high cost from phosphogypsum which is a phosphorite waste residue treated by a sulfuric acid wet method, provides a process for extracting rare earth in the process of treating the rare earth phosphorite by the sulfuric acid wet method with strong adaptability to mineral grade and type, combines the rare earth extraction and the wet phosphoric acid process, realizes the recovery of rare earth elements by a plurality of technical routes, is relatively easy to extract the rare earth, and is easy to realize industrial production.

In order to solve the technical problem, the invention provides a rare earth phosphate ore treatment method, which comprises the following steps:

(1) mixing rare earth phosphate ore and phosphoric acid to form mixed slurry;

(2) adding concentrated sulfuric acid into the mixed slurry at a rate of adding the concentrated sulfuric acidThe control method comprises the following steps: first, Ca in the mixed slurry is mixed²⁺The concentration is reduced from at least 1 wt% to Ca²⁺And SO₄ ^2-And then the SO in the mixed slurry is added₄ ^2-From Ca in concentration²⁺And SO₄ ^2-The equilibrium concentration of (2) is increased to at least 2 wt%, the mixed slurry is heated in the process of adding concentrated sulfuric acid to dissolve the rare earth phosphorite, and semi-hydrated gypsum and liquid obtained after heating the mixed slurry are obtained;

(3) recrystallizing the semi-hydrated gypsum obtained in the step (2) to obtain dihydrate gypsum and liquid obtained after the semi-hydrated gypsum is recrystallized.

The rare earth phosphate ore also contains monazite.

The rare earth phosphorite also contains monazite, at least one other rare earth independent ore and the like. The rare earth independent ore is mineral such as rare earth oxide, rare earth fluoride, rare earth carbonate, rare earth phosphate, rare earth silicate and the like.

Preferably, the control method of the adding speed of the concentrated sulfuric acid is as follows: first, Ca in the mixed slurry is mixed²⁺The concentration is reduced from at least 2 wt% to Ca²⁺And SO₄ ^2-And then the SO in the mixed slurry is added₄ ^2-From Ca in concentration²⁺And SO₄ ^2-To an equilibrium concentration of at least 2 wt%.

Preferably, the control method of the adding speed of the concentrated sulfuric acid is as follows: first, Ca in the mixed slurry is mixed²⁺The concentration is reduced from at least 2 wt% to Ca²⁺And SO₄ ^2-And then the SO in the mixed slurry is added₄ ^2-From Ca in concentration²⁺And SO₄ ^2-To an equilibrium concentration of at least 3 wt%.

Preferably, the heating temperature of the mixed slurry is 85-150 ℃; more preferably, the heating temperature of the mixed slurry is 95 to 130 ℃.

Preferably, the concentration of phosphoric acid in the mixed slurry is P₂O₅The weight percentage is 20wt percent to 50wt percent.

Preferably, the liquid-solid ratio (weight ratio) of the phosphoric acid to the rare earth phosphate ore in the mixed slurry is 1: 1-10: 1, preferably 1.5: 1-6: 1, and more preferably 2: 1-4: 1.

Preferably, the sum of the weights of Al ions, Fe ions and Si ions in the mixed slurry is controlled to be 0.1 to 3 wt% of the weight of the rare earth phosphate ore, calculated as their oxides, during the heating of the mixed slurry.

Preferably, the method further comprises the step of adding calcium sulfate seed crystals and/or active additives to the mixed slurry.

Preferably, the addition amount of the calcium sulfate crystal seeds is 0.1-30 wt% of the mass of the rare earth phosphate ore.

Preferably, the addition amount of the active additive is 0.0001-8 wt% of the mass of the rare earth phosphorite.

Preferably, the active additive is an organic additive and/or an inorganic additive.

Preferably, the organic additive comprises one or more of sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, cetyl trimethyl ammonium bromide, polyacrylamide, polyethylene glycol or polyvinyl alcohol.

Preferably, the inorganic additive comprises sodium polyphosphate, (NH)₄)₂SO₄、Na₂SO₄、NaCl、NH₄Cl、NH₄NO₃、NaNO₃One or more of; more preferably, the inorganic additive is (NH)₄)₂SO₄。

Preferably, when the hemihydrate gypsum is being recrystallized, SO in the solution is recrystallized₄ ^2-The concentration of (A) is 3 wt% -15 wt%.

Preferably, the method further comprises filtering the liquid obtained after the hemihydrate gypsum is recrystallized, and then returning a part of the filtered filtrate to the recrystallization solution of the hemihydrate gypsum.

The invention also provides a method for enriching rare earth from rare earth phosphorite, which comprises the following steps of treating the rare earth phosphorite according to the technical scheme; and (3) recovering the rare earth elements from the liquid obtained after the recrystallization of the hemihydrate gypsum.

Preferably, the rare earth elements recovered from the liquid obtained after the recrystallization of the hemihydrate gypsum are specifically:

recovering rare earth elements by adopting a neutralization precipitation method; or,

extracting and recovering radioactive elements and other rare earth elements in the liquid by using a solvent; or,

and evaporating and concentrating the liquid to obtain the rare earth phosphate.

Preferably, the method further comprises a step of recovering the rare earth element from the liquid obtained by heating the mixed slurry. The rare earth elements can be recovered by adopting a neutralization precipitation method; or, extracting and recovering radioactive elements and other rare earth elements in the liquid by using a solvent; or evaporating and concentrating the liquid to obtain the rare earth phosphate.

The invention provides a method for treating rare earth phosphate ore, which comprises the step of reacting concentrated sulfuric acid with mixed slurry of phosphoric acid and rare earth phosphate ore to produce crude phosphoric acid and semi-hydrated gypsum CaSO₄·1/2H₂O, because the dissolution condition of rare earth independent minerals such as monazite is harsh, the semi-aqueous method with higher reaction temperature and acidity is adopted for treatment, and in the process of generating the semi-aqueous gypsum, the adding speed of concentrated sulfuric acid is controlled to firstly lead SO in the mixed slurry to be firstly mixed₄ ^2-The defects are that the dissolving of the rare earth phosphorite is facilitated, and then the SO in the mixed slurry is controlled₄ ^2-And the excessive amount is beneficial to forming calcium sulfate crystals with good crystallization performance, and the eutectic adsorption effect of the rare earth is reduced, so that the rare earth is promoted to enter the phosphoric acid. At the same time, through controlThe concentration of aluminum and silicon ions in the phosphoric acid preparation solution is controlled to enable fluorine ions to form a complex with the aluminum and silicon ions, precipitation and precipitation of rare earth fluoride are reduced, eutectic and adsorption of rare earth and calcium sulfate are reduced by adding an active additive, and thus the leaching rate of rare earth is improved. Since part of the rare earth coexists with the hemihydrate gypsum, the dihydrate gypsum CaSO is obtained by recrystallizing the hemihydrate gypsum₄·2H₂After O, the rare earth entering the semi-hydrated gypsum can be released into the phosphoric acid solution, so that the subsequent recovery of the rare earth elements is facilitated.

The invention has the following functions and advantages:

1) because the independent rare earth minerals such as monazite have structural characteristics, the decomposition conditions are harsh relative to phosphate ores, strong acid and strong alkali are required to decompose under the high-temperature condition, and when the phosphate ores containing the independent rare earth minerals such as monazite are treated by adopting a sulfuric acid method wet method in the prior art, the enrichment degree of the rare earth in phosphoric acid can not be improved while the independent rare earth minerals are completely decomposed, so that the recovery of rare earth elements in subsequent processes is not facilitated. The invention adopts a semiwater method with higher reaction temperature and acidity than those of a dihydrate method to treat, controls the adding speed of concentrated sulfuric acid in the process of generating the semiwater gypsum, and firstly leads SO in mixed slurry to be firstly added₄ ^2-The defects are that the dissolving of the rare earth phosphorite is facilitated, and then the SO in the mixed slurry is controlled₄ ^2-And the excessive amount is beneficial to forming calcium sulfate crystals with good crystallization performance, and the eutectic adsorption effect of the rare earth is reduced, so that the rare earth is promoted to enter the phosphoric acid. The invention is not only suitable for single mineral species such as apatite, phosphorite and the like, but also suitable for mixed minerals of phosphorite containing rare earth independent minerals such as monazite.

2) In the process of treating phosphorite by sulfuric acid, the concentration of aluminum and silicon ions in the phosphoric acid solution is controlled to enable fluorine ions to form a complex with the phosphorus ions, so that the precipitation and the precipitation of rare earth fluoride are reduced, and the leaching of rare earth is improved.

3) Calcium sulfate crystallization is controlled in the process of treating phosphorite by sulfuric acid, so that the semi-hydrated-dihydrate recrystallization process is realized, rare earth carried in the calcium sulfate crystallization process is released, and the aim of improving the leaching rate of the rare earth is fulfilled.

4) The active additive is added in the process of treating the phosphorite by sulfuric acid to reduce the eutectic and adsorption of rare earth and calcium sulfate, thereby improving the leaching rate of the rare earth.

Detailed Description

The embodiment of the invention provides a method for enriching rare earth from rare earth phosphorite, which comprises the following steps:

(1) mixing rare earth phosphate ore and phosphoric acid to form slurry;

(2) adding concentrated sulfuric acid into the mixed slurry, wherein the adding speed of the sulfuric acid is controlled by the following mode: first, Ca in the mixed slurry is mixed²⁺The concentration is reduced from at least 1 wt% to Ca²⁺And SO₄ ^2-And then the SO in the mixed slurry is added₄ ^2-From Ca in concentration²⁺And SO₄ ^2-The equilibrium concentration of the mixed slurry is increased to at least 2 wt%, and the mixed slurry is heated in the process of adding concentrated sulfuric acid to dissolve the rare earth phosphorite to obtain semi-hydrated gypsum;

(3) recrystallizing the semi-hydrated gypsum obtained in the step (2) to obtain dihydrate gypsum;

the rare earth phosphate ore also contains monazite.

The rare earth phosphorite also contains monazite, at least one other rare earth independent ore and the like. The rare earth independent ore is rare earth oxide, rare earth fluoride, rare earth carbonate, rare earth phosphate and rare earth silicate rare earth independent mineral. Rare earth independent ores are well known to those skilled in the art, rare earth oxide ores such as cerite (Ce, Th) O₂Rare earth fluoride ores such as bastnaesite (Ce, La) F₃Yttrium fluorite (Ca, Y) F₂Rare earth carbonate ores such as bastnaesite (Ce, La) [ CO ]₃]F, carbon cerite (Ce, La)₂[CO₃]·8H₂O, rare earth phosphorusAcid salt ores such as xenotime Y [ PO ]₄]Rare earth silicates, e.g. scandium-yttrium (Sc, Y)₂[Si₂O₇]But is not limited thereto.

The Monazite (Monazite) of the invention refers to a compound of formula (Ln, Th) PO well known to those skilled in the art₄Wherein Ln means at least one of rare earth elements other than promethium. The proportion of monazite contained in the rare earth phosphate ore is not particularly limited, and may be in any range of 1 to 90 wt%.

According to the invention, the rare earth phosphate ore may comprise apatite (formula Ca)₅(PO₄)₃(F, Cl, OH)), phosphorite ore (molecular formula is Ca)₅F(PO₄)₃) Strontionite (molecular formula is SrAl)₃(PO₄)₂(OH)·H₂O), cerium-silicon apatite (molecular formula is (Ce, Ca)₅[SiO₄、PO₄]₃(OH, F)), yttrium silicon apatite (molecular formula is (Y, Ca)₅[SiO₄，PO₄]₃(OH, F)) in a solvent.

P in rare earth phosphate ore containing monazite₂O₅The content is preferably 5 to 40 wt%, more preferably 10 to 30 wt%.

According to the present invention, concentrated sulfuric acid is added to rare earth phosphate ore containing rare earth independent minerals such as monazite and phosphoric acid slurry, and the mixed slurry is heated during the addition of the concentrated sulfuric acid to dissolve the rare earth phosphate ore to produce hemihydrate gypsum. Since the dissolution conditions of rare earth independent minerals such as monazite are harsh, the addition speed of concentrated sulfuric acid is controlled in such a manner that Ca in the mixed slurry is first dissolved in the presence of Ca²⁺Excess, and then make SO in the mixed slurry₄ ^2-Excess, specifically: first, Ca in the mixed slurry is mixed²⁺The concentration is reduced from at least 1 wt% to Ca²⁺And SO₄ ^2-And then the SO in the mixed slurry is added₄ ^2-From Ca in concentration²⁺And SO₄ ^2-To an equilibrium concentration of at least 2 wt%. Preferably, Ca in the mixed slurry is first reacted²⁺The concentration is reduced from at least 2 wt% to Ca²⁺And SO₄ ^2-More preferably Ca²⁺The concentration is reduced from at least 3 wt% to Ca²⁺And SO₄ ^2-More preferably Ca²⁺The concentration is reduced from at least 3.5 wt% to Ca²⁺And SO₄ ^2-And then the SO in the mixed slurry is added₄ ^2-From Ca in concentration²⁺And SO₄ ^2-Is raised to at least 2 wt%, more preferably SO₄ ^2-From Ca in concentration²⁺And SO₄ ^2-To an equilibrium concentration of at least 3 wt.%, more preferably SO₄ ^2-From Ca in concentration²⁺And SO₄ ^2-To an equilibrium concentration of at least 5 wt%. According to the invention, Ca is contained in the mixed slurry²⁺And SO₄ ^2-The equilibrium concentration of (A) is CaSO₄＝Ca²⁺+SO₄ ^2-The calcium sulfate precipitate dissolves equilibrium concentrations.

According to the present invention, when concentrated sulfuric acid is added to a slurry of rare earth phosphate ore containing rare earth independent minerals such as monazite and phosphoric acid, the rate of addition of concentrated sulfuric acid is controlled SO that SO in the mixed slurry is first made₄ ^2-The defects are that the dissolving of the rare earth phosphorite is facilitated, and then the SO in the mixed slurry is controlled₄ ^2-This excess favors the incorporation of the rare earth into the phosphoric acid, the formation of hemihydrate gypsum, and the incorporation of more rare earth into the phosphoric acid solution. And then after the dihydrate gypsum is obtained through recrystallization, the rare earth entering the hemihydrate gypsum can enter the phosphoric acid again, so that the recovery of rare earth elements is facilitated.

According to the present invention, the heating temperature of the mixed slurry is preferably 85 to 150 ℃, more preferably 90 to 130 ℃, and still more preferably 100 to 120 ℃. The heating time of the mixed slurry is preferably 0.5 to 20 hours, and more preferably 1 to 5 hours.

The concentration of phosphoric acid in the mixed slurry is expressed as P₂O₅20 wt% to 50 wt%, more preferably 30 wt% to 50 wt%, and more preferably 40 wt% to 50 wt%, and the concentration of phosphoric acid in the mixed slurry may be controlled by adding phosphoric acid.

According to the invention, the weight ratio of phosphoric acid to rare earth phosphate ore in the mixed slurry is preferably 1: 1-10: 1, preferably 1.5: 1-6: 1, and more preferably 2: 1-4: 1.

According to the invention, the sum of the weights of Al ions, Fe ions and Si ions in the mixed slurry, calculated as their oxides, preferably accounts for 0.1-3 wt%, preferably 2-3 wt% of the weight of the phosphate ore. By controlling the concentration of Al ions, Fe ions and Si ions in the mixed slurry, fluorine ions in the mixed slurry form a complex with the Al ions, Fe ions and Si ions, the rare earth elements and fluorine can be prevented from forming rare earth fluoride to precipitate, and the rare earth can enter a phosphoric acid solution.

According to the invention, in order to facilitate the rare earth elements to enter into the phosphoric acid solution, in the process of producing the hemihydrate gypsum, calcium sulfate seed crystals and/or active additives are preferably added into the mixed slurry of the rare earth phosphorite containing monazite and the phosphoric acid, wherein the addition amount of the calcium sulfate seed crystals is 0.1-30 wt%, more preferably 5-30 wt%, and still more preferably 10-20 wt% of the mass of the rare earth phosphorite. The addition amount of the active additive is preferably 0.0001 wt% to 8 wt%, and more preferably 2 wt% to 5 wt% of the mass of the rare earth phosphate ore.

The active additive is an organic additive and/or an inorganic additive, and the organic additive can be one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, hexadecyl trimethyl ammonium bromide, polyacrylamide, polyethylene glycol or polyvinyl alcohol, but is not limited thereto; the inorganic additive can be sodium polyphosphate, (NH)₄)₂SO₄、Na₂SO₄、NaCl、NH₄Cl、NH₄NO₃、NaNO₃But are not limited thereto; the inorganic additive is more preferably (NH)₄)₂SO₄。

According to the invention, concentrated sulfuric acid reacts with phosphoric acid and rare earth phosphorite during heating to produce phosphoric acid and hemihydrate gypsum. To facilitate crystallization of hemihydrate gypsum, Ca is added to the mixed slurry²⁺Reduction to Ca²⁺And SO₄ ^2-After the equilibrium concentration of (a), the gypsum is preferably crystallized by placing the mixed slurry in a crystallization tank and allowing SO in the mixed slurry in the crystallization tank to crystallize₄ ^2-Is maintained at a concentration of 0.3 wt% to 8 wt%, more preferably 5 wt% to 8 wt%, so that the gypsum grows at a suitable growth rate to obtain good filtration performance.

According to the present invention, after hemihydrate gypsum is produced, the hemihydrate gypsum is recrystallized to produce dihydrate gypsum. Recrystallization may be carried out by methods well known to those skilled in the art. For example, hemihydrate gypsum is mixed with phosphoric acid at a concentration P₂O₅Preferably 1 to 30 wt%, more preferably 3 to 20 wt%, and then adding sulfuric acid to recrystallize the hemihydrate gypsum at a temperature of 45 to 85 ℃, more preferably 50 to 70 ℃ to form dihydrate gypsum, SO₄ ^2-The concentration is controlled to be 3 wt% to 15 wt%, more preferably 4 wt% to 12 wt%, and still more preferably 6 wt% to 12 wt%.

Preferably, after the hemihydrate gypsum is dissolved in phosphoric acid for recrystallization, rare earth elements enter the phosphoric acid, and then the phosphoric acid solution containing the rare earth elements is obtained through filtration. In addition, the rare earth-containing phosphoric acid solution can be reused as a recrystallized phosphoric acid solution or for dissolving phosphate ore and pulping.

processing rare earth according to the scheme;

and (3) recovering rare earth elements from the liquid obtained after the recrystallization of the hemihydrate gypsum.

According to the present invention, the recovery of rare earth elements from the liquid after recrystallization of the hemihydrate gypsum can be carried out according to methods well known to those skilled in the art. For example, the recrystallization liquid is first filtered, and then the obtained filtrate is treated to obtain a rare earth phosphate precipitate, and specific examples thereof may be such that the filtrate is treated by a neutralization precipitation method well known to those skilled in the art to obtain a rare earth phosphate solution; or evaporating and concentrating the filtrate to precipitate the rare earth in a phosphate form, and filtering to obtain phosphoric acid and rare earth phosphate precipitate.

In accordance with the present invention, the radioactive element U, Th in the filtrate may also be recovered using an extraction agent, which may be an acidic extraction agent and/or a neutral extraction agent. Specific examples of the acidic extractant include a bis- (2-ethylhexyl) phosphoric acid extractant as a main component, which is commercially available under the trade name P204; if the main component is 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester with the trade name of P507; the acidic extractant is not limited thereto. Specific examples of the neutral extractant are tributyl phosphate (TBP), trialkylphosphine oxide (TRPO), trioctylphosphine oxide (TOPO), but are not limited thereto. When the extracting agent is used for recovering U, Th, the extracting agent is preferably diluted by a diluent, and the volume ratio of the extracting agent to the diluent is preferably 1: 9-4: 1. Herein, the diluent mentioned is preferably at least one of n-hexane, n-heptane, octane, nonane, decane, kerosene, sulfonated kerosene, solvent oil and alcohol.

According to the invention, at least one of ketone, ether, alcohol and ester organic solvent can be selected as the extractant to extract the raffinate after U, Th is recovered, so that refined phosphoric acid and raffinate can be obtained. Preferably, the extractant and the diluent are mixed for use, and the preferred volume ratio of the extractant to the diluent is 1: 9-4: 1. The raffinate obtained in the step can be prepared into rare earth phosphate precipitate by a neutralization precipitation method or extracted by an acidic extractant or a neutral extractant, and then the rare earth chloride is obtained by back extraction by hydrochloric acid.

According to the invention, the method comprisesAfter the liquid of the semi-hydrated gypsum recrystallization is treated by an evaporation concentration or neutralization precipitation method to obtain rare earth phosphate, the rare earth phosphate can be decomposed, washed and filtered according to an alkaline treatment method well known by the technical personnel in the field to obtain rare earth hydroxide, and then the rare earth hydroxide is dissolved by hydrochloric acid to prepare mixed RECl₃Removing impurities from the solution, extracting and separating single rare earth or producing mixed rare earth carbonate by carbonate precipitation; or,

adding a compound and concentrated sulfuric acid into the rare earth phosphate, roasting, leaching, filtering to obtain a rare earth sulfate leaching solution, neutralizing or extracting to remove impurities to obtain a pure rare earth sulfate solution, and further extracting and separating or producing mixed rare earth by adopting carbonate precipitation.

According to the invention, after the rare earth phosphate compound and concentrated sulfuric acid are roasted, soaked in water and filtered to obtain rare earth sulfate water extract, the sulfuric acid water extract can also be mixed with K⁺、Na⁺、NH₄ ⁺Form a rare earth sulfate double salt precipitate, said K⁺、Na⁺、NH₄ ⁺The molar ratio of the added inorganic acid salt to the sulfuric acid roasting water leaching solution is RE to M2-5 to 1, and M is K⁺、Na⁺、NH₄ ⁺. After obtaining rare earth sulfate double salt, decomposing the rare earth sulfate double salt precipitate according to an alkaline method well known by the technical personnel in the field, washing with water, filtering to obtain rare earth hydroxide, and dissolving by adopting hydrochloric acid to prepare mixed RECl₃And (3) removing impurities from the solution, extracting and separating or producing mixed rare earth carbonate by adopting carbonate precipitation.

The alkaline treatment according to the invention is preferably: adding 30-60 wt% NaOH solution into the rare earth phosphate precipitate, wherein the reaction temperature is 120-170 ℃, and the reaction time is 0.5-7 hours. The volume ratio of the solid to the water in the water washing procedure is preferably 1: 3-1: 20, a 5-15-stage continuous countercurrent washing mode well known to those skilled in the art is preferably adopted, and the washing temperature is preferably 30-95 ℃, more preferably 40-80 ℃, and more preferably 50-70 ℃. In the hydrochloric acid dissolving procedure, the concentration of hydrochloric acid is preferably not less than 30 wt%, and the dissolving temperature is preferably 70-95 ℃; the concentration of the finally obtained rare earth chloride solution is preferably 100-300 g/L.

When the rare earth phosphate precipitate is roasted by concentrated sulfuric acid, the concentration of the concentrated sulfuric acid is preferably 90-98 wt%, the roasting temperature is preferably 100-800 ℃, the weight ratio of the concentrated sulfuric acid to the rare earth phosphate precipitate is preferably 1-3: 1, the roasting time is preferably 0.5-5 hours, and the liquid-solid weight ratio is preferably 2-15: 1 during water immersion.

According to the present invention, the phosphoric acid produced in the step of forming hemihydrate gypsum can be treated to enrich rare earth in the same manner as described above for rare earth from the recrystallized filtrate. In the case of enriching the rare earth in the phosphoric acid for producing hemihydrate gypsum, the phosphoric acid may be mixed with a filtrate of recrystallization, and then the rare earth may be enriched by the method described above for enriching the filtrate.

In order to further understand the present invention, the following describes the processing method of rare earth phosphorite and the method for enriching rare earth from rare earth phosphorite, which are provided by the present invention, with reference to the examples.

Example 1

Preparing mixed slurry: taking 100g of rare earth phosphate ore, wherein 13g of monazite ore is contained, and the content of rare earth in the phosphate ore is 7.8 wt%. Mixing the rare earth phosphate ore with P containing 20 wt% according to the liquid-solid ratio of 10: 1₂O₅Uniformly stirring the phosphoric acid solution to obtain mixed slurry;

② addition nucleating agent: adding 30g of calcium sulfate seed crystal and 0.1g of polyethylene glycol additive into the mixed slurry, and uniformly stirring;

③ adding concentrated sulfuric acid: slowly adding concentrated sulfuric acid with the concentration of 98 wt% into the mixed slurry, simultaneously heating the mixed slurry to 150 ℃, and controlling the weight of Al ions and Fe ions in the mixed slurry when heating the mixed slurryAnd (on their oxide basis) 0.1 wt% of the rare earth phosphate ore. Stirring and reacting for 5 hours to ensure that Ca in the mixed slurry is contained²⁺From 2 wt% down to Ca²⁺And SO₄ ^2-After the equilibrium concentration of (3), the SO in the mixed slurry is added₄ ^2-From Ca²⁺And SO₄ ^2-The equilibrium concentration of the raw phosphoric acid is increased to 4 wt% to obtain semi-hydrated gypsum, and the mixed slurry is filtered to obtain crude phosphoric acid and semi-hydrated gypsum, wherein the rare earth in the crude phosphoric acid accounts for 63.5 wt% of the total amount of the rare earth;

fourthly, recrystallization: mixing the semi-hydrated gypsum with 5 wt% of P₂O₅The temperature of the mixed solution was controlled to 85 ℃, the mixed solution was stirred for 5 hours, and free SO in the mixed solution was dissolved by adding 98 wt% of concentrated sulfuric acid₄ ^2-Controlling the concentration to be 15 wt%, recrystallizing the gypsum, then filtering, and measuring the amount of the rare earth entering the filtrate to be 19.8 wt% of the total amount of the rare earth;

neutralizing and precipitating: mixing the filtrate obtained in the step (iv) and the crude phosphoric acid obtained in the step (iii), adding a sodium hydroxide solution with a concentration of 20 wt%, and stirring the mixture to obtain rare earth phosphate precipitation slurry;

sixthly, alkaline decomposition: adding 30 wt% NaOH solution into the rare earth phosphate precipitation slurry, stirring the mixture, controlling the temperature of the mixture at 120 ℃, and reacting for 1 hour to obtain rare earth hydroxide slurry;

and (c) washing with water: washing the obtained rare earth hydroxide slurry by adopting a 10-grade continuous countercurrent washing mode, wherein in the step, the ratio of solid to water is 1: 1, the washing temperature is 40 ℃, and then filtering to obtain solid rare earth hydroxide;

dissolving with hydrochloric acid: dissolving the solid rare earth hydroxide by using a hydrochloric acid solution with the concentration of 30 wt%, wherein in the step, the reaction temperature is controlled to be 70 ℃ to obtain a rare earth chloride solution;

ninthly, preparing mixed rare earth carbonate: and (3) mixing the rare earth chloride solution with 30 wt% of sodium carbonate solution, precipitating mixed rare earth carbonate, and testing that the content of rare earth in the mixed rare earth carbonate accounts for 81.2% of the weight of the raw material rare earth.

Example 2

Preparing mixed slurry: taking 100g of rare earth phosphate ore containing 3g of monazite and 2g of cerite (Ce, Th) O₂The content of rare earth in the phosphorite is 3.4 wt%. Mixing the rare earth phosphate ore with P containing 50 wt% according to the liquid-solid ratio of 1: 1₂O₅Uniformly stirring the phosphoric acid solution to obtain mixed slurry;

② addition nucleating agent: adding 15g of calcium sulfate seed crystal and 0.3g of polyvinyl alcohol additive into the mixed slurry, and uniformly stirring;

③ adding concentrated sulfuric acid: concentrated sulfuric acid with the concentration of 98 wt% is slowly added into the mixed slurry, the mixed slurry is heated to 88 ℃, and when the mixed slurry is heated, the weight sum (calculated by oxides of Fe ions and Si ions) of Fe ions and Si ions in the mixed slurry accounts for 0.3 wt% of the weight of the rare earth phosphate ore. Stirring and reacting for 5 hours to ensure that Ca in the mixed slurry is contained²⁺From 2.5 wt% down to Ca²⁺And SO₄ ^2-After the equilibrium concentration of (3), the SO in the mixed slurry is added₄ ^2-From Ca²⁺And SO₄ ^2-The equilibrium concentration of the mixed slurry is increased to 3.5 wt% to obtain semi-hydrated gypsum, and the mixed slurry is filtered to obtain crude phosphoric acid and semi-hydrated gypsum, wherein the rare earth in the crude phosphoric acid accounts for 65.1 wt% of the total amount of the rare earth;

fourthly, recrystallization: mixing the semi-hydrated gypsum with 30 wt% of P₂O₅The temperature of the mixed solution was controlled at 45 ℃, the mixed solution was stirred for 5 hours, and free SO in the mixed solution was dissolved by adding 98 wt% of concentrated sulfuric acid₄ ^2-Controlling the concentration to be 3 wt%, recrystallizing the gypsum, then filtering, and measuring the content of the rare earth entering the filtrate to be 22.3 wt% of the total content of the rare earth;

ninthly, preparing mixed rare earth carbonate: and (3) mixing the rare earth chloride solution with 30 wt% of sodium carbonate solution, precipitating mixed rare earth carbonate, and testing that the content of rare earth in the mixed rare earth carbonate accounts for 85.3% of the weight of the raw material rare earth.

Example 3

Preparing mixed slurry: taking 100g of rare earth phosphate ore containing 20g of monazite and 5-bastnaesite (Ce, La) F₃The content of rare earth in the phosphorite is 12 wt%. Mixing the rare earth phosphate ore with P containing 50 wt% according to the liquid-solid ratio of 4: 1₂O₅Uniformly stirring the phosphoric acid solution to obtain mixed slurry;

② addition nucleating agent: adding 10g of calcium sulfate crystal seeds and 2.8g of polyacrylamide additive into the mixed slurry, and uniformly stirring;

③ adding concentrated sulfuric acid: slowly adding the concentrate into the mixed slurryConcentrated sulfuric acid with the degree of 98 wt% is simultaneously heated to 140 ℃, and when the mixed slurry is heated, the sum of the weight of Al ions, Fe ions and Si ions (calculated by oxides thereof) in the mixed slurry is controlled to be 3 wt% of the weight of the rare earth phosphate ore. Stirring and reacting for 5 hours to ensure that Ca in the mixed slurry is contained²⁺From 2.6 wt% down to Ca²⁺And SO₄ ^2-After the equilibrium concentration of (3), the SO in the mixed slurry is added₄ ^2-From Ca²⁺And SO₄ ^2-The equilibrium concentration of the raw phosphoric acid is increased to 4 wt% to obtain semi-hydrated gypsum, and the mixed slurry is filtered to obtain crude phosphoric acid and semi-hydrated gypsum, wherein the rare earth in the crude phosphoric acid accounts for 60.2 wt% of the total amount of the rare earth;

fourthly, recrystallization: mixing the semi-hydrated gypsum with 18 wt% of P₂O₅The temperature of the mixed solution was controlled at 50 ℃, the mixed solution was stirred for 5 hours, and free SO in the mixed solution was dissolved by adding 98 wt% of concentrated sulfuric acid₄ ^2-Controlling the concentration to be 12 wt%, recrystallizing the gypsum, then filtering, and measuring the content of the rare earth entering the filtrate to be 22.6 wt% of the total content of the rare earth;

fifthly, extraction: providing a TBP: extracting crude phosphoric acid obtained in the third step by using an extracting agent mixed with kerosene in a weight ratio of 1: 1, adding a sodium hydroxide solution with the concentration of 20 wt% into raffinate, and stirring the mixture to obtain rare earth phosphate precipitation slurry;

ninthly, preparing mixed rare earth carbonate: and (3) mixing the rare earth chloride solution with 30 wt% of sodium carbonate solution, precipitating mixed rare earth carbonate, and testing that the content of rare earth in the mixed rare earth carbonate accounts for 80.1% of the weight of the raw material rare earth.

Example 4

Preparing mixed slurry: taking 100g of rare earth phosphate ore, wherein the content of the rare earth phosphate ore contains 35g of monazite ore, and the content of the rare earth in the phosphate ore is 16 wt%. Mixing the rare earth phosphate ore with P containing 35 wt% according to the liquid-solid ratio of 6: 1₂O₅Uniformly stirring the phosphoric acid solution to obtain mixed slurry;

② addition nucleating agent: adding 25g of calcium sulfate seed crystal into the mixed slurry, and uniformly stirring;

③ adding concentrated sulfuric acid: concentrated sulfuric acid with the concentration of 98 wt% is slowly added into the mixed slurry, the mixed slurry is heated to 140 ℃, and when the mixed slurry is heated, the sum of the weight of Al ions and the weight of Si ions (calculated by oxides of the Al ions and the Si ions) in the mixed slurry accounts for 1.5 wt% of the weight of the rare earth phosphate ore. Stirring and reacting for 5 hours to ensure that Ca in the mixed slurry is contained²⁺From 2.6 wt% down to Ca²⁺And SO₄ ^2-After the equilibrium concentration of (3), the SO in the mixed slurry is added₄ ^2-From Ca²⁺And SO₄ ^2-The equilibrium concentration of the raw phosphoric acid is increased to 5 wt% to obtain semi-hydrated gypsum, and the mixed slurry is filtered to obtain crude phosphoric acid and semi-hydrated gypsum, wherein the rare earth in the crude phosphoric acid accounts for 56.6 wt% of the total amount of the rare earth;

fourthly, recrystallization: mixing the semi-hydrated gypsum with 21 wt% of P₂O₅The temperature of the mixed solution was controlled at 70 ℃, the mixed solution was stirred for 5 hours, and free SO in the mixed solution was dissolved by adding 98 wt% of concentrated sulfuric acid₄ ^2-Controlling the concentration to be 4.3 wt%, recrystallizing the gypsum, then filtering, and measuring the content of the rare earth entering the filtrate to be 23.6 wt% of the total content of the rare earth;

fifthly, extraction: providing an extracting agent mixed by P507, TRPO and nonane according to the weight ratio of 1: 9, mixing the filtrate obtained in the step (iv) and the crude phosphoric acid obtained in the step (iii), extracting by using the extracting agent, adding a sodium hydroxide solution with the concentration of 20 wt% into raffinate, and stirring the mixture to obtain rare earth phosphate precipitation slurry;

sixthly, alkaline decomposition: adding 30 wt% NaOH solution into the rare earth phosphate precipitation slurry, stirring the mixture, controlling the temperature of the mixture to be 110 ℃, and reacting for 2 hours to obtain rare earth hydroxide slurry;

and (c) washing with water: washing the obtained rare earth hydroxide slurry by adopting a 10-grade continuous countercurrent washing mode, wherein in the step, the ratio of solid to water is 1: 2, the washing temperature is 45 ℃, and then filtering to obtain solid rare earth hydroxide;

dissolving with hydrochloric acid: dissolving the solid rare earth hydroxide by using a hydrochloric acid solution with the concentration of 30 wt%, wherein in the step, the reaction temperature is controlled to be 65 ℃ to obtain a rare earth chloride solution;

ninthly, preparing mixed rare earth carbonate: and (3) mixing the rare earth chloride solution with 30 wt% of sodium carbonate solution, precipitating mixed rare earth carbonate, and testing that the content of rare earth in the mixed rare earth carbonate accounts for 78.7% of the weight of the raw material rare earth.

Example 5

Preparing mixed slurry: taking 100g of rare earth phosphate ore containing 20g of monazite and 6-bastnaesite (Ce, La) [ CO ]₃]F, the content of the rare earth in the phosphorite is 9.1 wt%. Mixing the rare earth phosphate ore with P containing 35 wt% according to the liquid-solid ratio of 6: 1₂O₅Uniformly stirring the phosphoric acid solution to obtain mixed slurry;

② addition nucleating agent: to the mixed slurry was added 3g of (NH)₄)₂SO₄Stirring uniformly;

③ adding concentrated sulfuric acid: concentrated sulfuric acid with the concentration of 98 wt% is slowly added into the mixed slurry, the mixed slurry is heated to 140 ℃, and when the mixed slurry is heated, the sum of the weight of Al ions, Fe ions and Si ions (calculated by oxides thereof) in the mixed slurry is controlled to be 2.5 wt% of the weight of the rare earth phosphate ore. Stirring and reacting for 5 hours to ensure that Ca in the mixed slurry is contained²⁺From 2.8 wt% down to Ca²⁺And SO₄ ^2-After the equilibrium concentration of (3), the SO in the mixed slurry is added₄ ^2-From Ca²⁺And SO₄ ^2-The equilibrium concentration of the mixed slurry is increased to 3.8 wt% to obtain semi-hydrated gypsum, and the mixed slurry is filtered to obtain crude phosphoric acid and semi-hydrated gypsum, wherein the rare earth in the crude phosphoric acid accounts for 64.1 wt% of the total amount of the rare earth;

fourthly, recrystallization: mixing the semi-hydrated gypsum with 18 wt% of P₂O₅The temperature of the mixed solution was controlled at 60 ℃, the mixed solution was stirred for 5 hours, and free SO in the mixed solution was dissolved by adding 98 wt% of concentrated sulfuric acid₄ ^2-Controlling the concentration to be 7.8 wt%, recrystallizing the gypsum, then filtering, and measuring the content of the rare earth entering the filtrate to be 23.6 wt% of the total content of the rare earth;

fifthly, extraction: providing an extractant mixed by P204, TOPO and decane according to the weight ratio of 1: 8, mixing the filtrate obtained in the step (v) and the crude phosphoric acid obtained in the step (iv), extracting by using the extractant, adding a sodium hydroxide solution with the concentration of 20 wt% into the extract liquor, stirring the mixture to obtain rare earth phosphate precipitation slurry, and filtering to obtain solid rare earth phosphate;

sixthly, roasting with sulfuric acid: mixing the solid rare earth phosphate precipitate with concentrated sulfuric acid with the concentration of 98 wt% according to the weight ratio of 1: 1, and roasting for 1 hour at 600 ℃;

and (c) soaking in water: taking the roasted product for water leaching, wherein the liquid-solid ratio of the water leaching is 5: 1, the water leaching time is 1 hour, and then filtering to obtain rare earth sulfate water leaching solution;

preparing mixed rare earth carbonate: mixing the rare earth sulfate water extract with a KCl solution with the concentration of 20 wt% to prepare a rare earth sulfate double salt solution;

ninthly, alkaline treatment: adding 30 wt% NaOH solution into the rare earth sulfate double salt precipitation slurry, stirring the mixture, controlling the temperature of the mixture to be 110 ℃, and reacting for 2 hours to obtain rare earth hydroxide slurry;

r, water washing: washing the obtained rare earth hydroxide slurry by adopting a 10-grade continuous countercurrent washing mode, wherein in the step, the ratio of solid to water is 1: 2, the washing temperature is 45 ℃, and then filtering to obtain solid rare earth hydroxide;

(11) dissolving hydrochloric acid: dissolving the solid rare earth hydroxide by using a hydrochloric acid solution with the concentration of 30 wt%, wherein in the step, the reaction temperature is controlled to be 65 ℃ to obtain a rare earth chloride solution;

(12) and preparing mixed rare earth carbonate: and (3) mixing the rare earth chloride solution with 30 wt% of sodium carbonate solution, precipitating mixed rare earth carbonate, wherein the content of rare earth in the mixed rare earth carbonate accounts for 84.2% of the weight of the raw material rare earth through tests.

Example 6

Preparing mixed slurry: taking 100g of rare earth phosphate ore, wherein the rare earth phosphate ore contains 21g of monazite ore, and the content of rare earth in the phosphate ore is 6.8 wt%. Mixing the rare earth phosphate ore with P containing 40 wt% according to the liquid-solid ratio of 6: 1₂O₅Uniformly stirring the phosphoric acid solution to obtain mixed slurry;

② addition nucleating agent: to the mixed slurry were added 18g of calcium sulfate seed crystals and 0.3g of NH₄NO₃Adding the additive, and uniformly stirring;

③ adding concentrated sulfuric acid: the mixingSlowly adding 98 wt% concentrated sulfuric acid into the slurry, heating the mixed slurry to 140 deg.C, stirring for 5 hr to make Ca in the mixed slurry²⁺From 2.2 wt% down to Ca²⁺And SO₄ ^2-After the equilibrium concentration of (3), the SO in the mixed slurry is added₄ ^2-From Ca²⁺And SO₄ ^2-The equilibrium concentration of the mixed slurry is increased to 4.5 wt% to obtain semi-hydrated gypsum, and the mixed slurry is filtered to obtain crude phosphoric acid and semi-hydrated gypsum, wherein the rare earth in the crude phosphoric acid accounts for 67.4 wt% of the total amount of the rare earth;

fourthly, recrystallization: mixing the semi-hydrated gypsum with 16 wt% of P₂O₅The temperature of the mixed solution was controlled to 65 ℃, the mixed solution was stirred for 5 hours, and free SO in the mixed solution was dissolved by adding 98 wt% of concentrated sulfuric acid₄ ^2-Controlling the concentration to be 9.7 wt%, recrystallizing the gypsum, then filtering, and measuring the content of the rare earth entering the filtrate to be 27.1 wt% of the total content of the rare earth;

neutralizing and precipitating: mixing the filtrate obtained in the fifth step with the crude phosphoric acid obtained in the fourth step, adding a sodium hydroxide solution with the concentration of 20 wt%, and stirring the mixture to obtain rare earth phosphate precipitation slurry;

ninthly, preparing mixed rare earth carbonate: and (3) mixing the rare earth chloride solution with 30 wt% of sodium carbonate solution, precipitating mixed rare earth carbonate, and testing that the content of rare earth in the mixed rare earth carbonate accounts for 92.3% of the weight of the raw material rare earth.

Example 7

Preparing mixed slurry: taking 100g of rare earth phosphorite, wherein the rare earth phosphorite contains 11g of monazite ore, and the content of rare earth in the phosphorite is 3.4wt per mill. Mixing the rare earth phosphate ore with P containing 40 wt% according to the liquid-solid ratio of 6: 1₂O₅Uniformly stirring the phosphoric acid solution to obtain mixed slurry;

② addition nucleating agent: adding 5g of sodium dodecyl sulfate into the mixed slurry, and uniformly stirring;

③ adding concentrated sulfuric acid: concentrated sulfuric acid with the concentration of 98 wt% is slowly added into the mixed slurry, the mixed slurry is heated to 140 ℃, and when the mixed slurry is heated, the weight sum (calculated by oxides of the Fe ions and the Si ions) of the mixed slurry accounts for 2.8 wt% of the weight of the rare earth phosphate ore. Stirring and reacting for 5 hours to ensure that Ca in the mixed slurry is contained²⁺From 2.2 wt% down to Ca²⁺And SO₄ ^2-After the equilibrium concentration of (3), the SO in the mixed slurry is added₄ ^2-From Ca²⁺And SO₄ ^2-The equilibrium concentration of the raw phosphoric acid is increased to 4.5 wt% to obtain semi-hydrated gypsum, and the mixed slurry is filtered to obtain crude phosphoric acid and semi-hydrated gypsum, wherein the rare earth in the crude phosphoric acid accounts for 60.6 wt% of the total amount of the rare earth;

fourthly, recrystallization: mixing the semi-hydrated gypsum with 22 wt% of P₂O₅The temperature of the mixed solution was controlled at 62 ℃, the mixed solution was stirred for 5 hours, and free SO in the mixed solution was dissolved by adding 98 wt% of concentrated sulfuric acid₄ ^2-Controlling the concentration to be 7.8 wt%, recrystallizing the gypsum, then filtering, and measuring the amount of the rare earth entering the filtrate to be 26.4 wt% of the total amount of the rare earth;

ninthly, preparing mixed rare earth carbonate: and (3) mixing the rare earth chloride solution with 30 wt% of sodium carbonate solution, precipitating mixed rare earth carbonate, and testing that the content of rare earth in the mixed rare earth carbonate accounts for 82.7% of the weight of the raw material rare earth.

Example 8

Preparing mixed slurry: taking 100g of rare earth phosphate ore, wherein the content of the rare earth in the phosphate ore is 1.8 wt%, and the content of the monazite ore is 3.8 g. Mixing the rare earth phosphate ore with P containing 40 wt% according to the liquid-solid ratio of 6: 1₂O₅Uniformly stirring the phosphoric acid solution to obtain mixed slurry;

② addition nucleating agent: to the mixed slurry were added 18g of calcium sulfate seed crystal and 1.5g of (NH)₄)₂SO₄Adding the additive, and uniformly stirring;

③ adding concentrated sulfuric acid: the mixed slurry is slowly added with the concentration of 98wt percentConcentrated sulfuric acid, and simultaneously heating the mixed slurry to 140 ℃, and heating the mixed slurry. Stirring and reacting for 5 hours to ensure that Ca in the mixed slurry is contained²⁺From 2.2 wt% down to Ca²⁺And SO₄ ^2-After the equilibrium concentration of (3), the SO in the mixed slurry is added₄ ^2-From Ca²⁺And SO₄ ^2-The equilibrium concentration of the mixed slurry is increased to 4.5 wt% to obtain semi-hydrated gypsum, and the mixed slurry is filtered to obtain crude phosphoric acid and semi-hydrated gypsum, wherein the rare earth in the crude phosphoric acid accounts for 63.4 wt% of the total amount of the rare earth;

fourthly, recrystallization: mixing the semi-hydrated gypsum with 23 wt% of P₂O₅The temperature of the mixed solution was controlled at 68 ℃, the mixed solution was stirred for 5 hours, and free SO in the mixed solution was dissolved by adding 98 wt% of concentrated sulfuric acid₄ ^2-Controlling the concentration to be 11.4 wt%, recrystallizing the gypsum, then filtering, and measuring the content of the rare earth entering the filtrate to be 25.1 wt% of the total content of the rare earth;

ninthly, preparing mixed rare earth carbonate: and (3) mixing the rare earth chloride solution with 30 wt% of sodium carbonate solution, precipitating mixed rare earth carbonate, and testing that the content of rare earth in the mixed rare earth carbonate accounts for 81.7% of the weight of the raw material rare earth.

Example 9

② addition nucleating agent: adding 8g of hexadecyl trimethyl ammonium bromide additive into the mixed slurry, and uniformly stirring;

③ adding concentrated sulfuric acid: and slowly adding concentrated sulfuric acid with the concentration of 98 wt% into the mixed slurry, heating the mixed slurry to 140 ℃, and controlling the weight of Al ions, Fe ions and Si ions (calculated by oxides thereof) in the mixed slurry to be 2.8 wt% of the weight of the rare earth phosphate ore when heating the mixed slurry. Stirring and reacting for 5 hours to ensure that Ca in the mixed slurry is contained²⁺From 2.2 wt% down to Ca²⁺And SO₄ ^2-After the equilibrium concentration of (3), the SO in the mixed slurry is added₄ ^2-From Ca²⁺And SO₄ ^2-The equilibrium concentration of the mixed slurry is increased to 4.5 wt% to obtain semi-hydrated gypsum, and the mixed slurry is filtered to obtain crude phosphoric acid and semi-hydrated gypsum, wherein the rare earth in the crude phosphoric acid accounts for 56.3 wt% of the total amount of the rare earth;

fourthly, recrystallization: mixing the semi-hydrated gypsum with 25 wt% of P₂O₅The temperature of the mixed solution was controlled at 75 ℃, the mixed solution was stirred for 5 hours, and free SO in the mixed solution was dissolved by adding 98 wt% of concentrated sulfuric acid₄ ^2-Controlling the concentration to be 10.6 wt%, recrystallizing the gypsum, then filtering, and measuring the content of the rare earth entering the filtrate to be 30.2 wt% of the total content of the rare earth;

ninthly, preparing mixed rare earth carbonate: and (3) mixing the rare earth chloride solution with 30 wt% of sodium carbonate solution, precipitating mixed rare earth carbonate, and testing that the content of rare earth in the mixed rare earth carbonate accounts for 80.3% of the weight of the raw material rare earth.

Example 10

Preparing mixed slurry: taking 100g of rare earth phosphate ore, which contains 12g monazite ore and 3g of xenotime Y [ PO ]₄]1g cerite (Ce, La)₂[CO₃]·8H₂O, 3g rare earth silicates such as scandium-yttrium (Sc, Y)₂[Si₂O₇]The content of rare earth in the phosphorite is 6.8 wt%. Mixing the rare earth phosphate ore with P containing 40 wt% according to the liquid-solid ratio of 6: 1₂O₅Uniformly stirring the phosphoric acid solution to obtain mixed slurry;

② addition nucleating agent: adding 18g of calcium sulfate crystal seeds and 5g of polyethylene glycol additive into the mixed slurry, and uniformly stirring;

③ adding concentrated sulfuric acid: and slowly adding concentrated sulfuric acid with the concentration of 98 wt% into the mixed slurry, heating the mixed slurry to 140 ℃, and controlling the weight of Al ions, Fe ions and Si ions (calculated by oxides thereof) in the mixed slurry to be 2.8 wt% of the weight of the rare earth phosphate ore when heating the mixed slurry. Stirring and reacting for 5 hours to ensure that Ca in the mixed slurry is contained²⁺From 2.2 wt% down to Ca²⁺And SO₄ ^2-After the equilibrium concentration of (3), the SO in the mixed slurry is added₄ ^2-From Ca²⁺And SO₄ ^2-The equilibrium concentration of the mixed slurry is increased to 4.5 wt% to obtain semi-hydrated gypsum, and the mixed slurry is filtered to obtain crude phosphoric acid and semi-hydrated gypsum, wherein the rare earth in the crude phosphoric acid accounts for 51.4 wt% of the total amount of the rare earth;

fourthly, recrystallization: mixing the semi-hydrated gypsum with 28 wt% of P₂O₅The temperature of the mixed solution was controlled to 78 ℃, the mixed solution was stirred for 5 hours, and free SO in the mixed solution was dissolved by adding 98 wt% of concentrated sulfuric acid₄ ^2-Controlling the concentration to be 8.8 wt%, recrystallizing the gypsum, then filtering, and measuring the content of the rare earth entering the filtrate to be 23.3 wt% of the total content of the rare earth;

ninthly, preparing mixed rare earth carbonate: and (3) mixing the rare earth chloride solution with 30 wt% of sodium carbonate solution, precipitating mixed rare earth carbonate, and testing that the content of rare earth in the mixed rare earth carbonate accounts for 70.7% of the weight of the raw material rare earth.

The method for enriching rare earth from rare earth phosphorite provided by the invention is described in detail above. The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. A rare earth phosphorite treatment method comprises the following steps:

(1) mixing rare earth phosphorite with phosphoric acid to form mixed slurry, wherein the rare earth phosphorite also contains monazite;

(2) adding concentrated sulfuric acid into the mixed slurry, wherein the adding mode of the concentrated sulfuric acid is as follows: first, Ca in the mixed slurry is mixed²⁺The concentration is reduced from at least 1 wt% to Ca²⁺And SO₄ ^2-And then the SO in the mixed slurry is added₄ ^2-From Ca in concentration²⁺And SO₄ ^2-The equilibrium concentration of the mixed slurry is increased to at least 2 wt%, the mixed slurry is heated in the process of adding concentrated sulfuric acid, the heating temperature is 90-150 ℃, so that the rare earth phosphorite is dissolved, and semi-hydrated gypsum and liquid obtained after heating the mixed slurry are obtained;

2. The method of treating rare earth phosphate ore according to claim 1, wherein the rare earth phosphate ore further comprises monazite and at least one rare earth independent ore.

3. The method of treating rare earth phosphate ore according to claim 2, wherein the rare earth independent ore is rare earth oxide, rare earth fluoride, rare earth carbonate, rare earth phosphate, and rare earth silicate minerals.

4. The method for treating rare earth phosphate ore according to claim 1, wherein the concentrated sulfuric acid is added in the following manner: first, Ca in the mixed slurry is mixed²⁺The concentration is reduced from at least 2 wt% to Ca²⁺And SO₄ ^2-And then the SO in the mixed slurry is added₄ ^2-From Ca in concentration²⁺And SO₄ ^2-To an equilibrium concentration of at least 2 wt%.

5. The method for treating rare earth phosphate ore according to claim 4, wherein the concentrated sulfuric acid is added in the following manner: first, Ca in the mixed slurry is mixed²⁺The concentration is reduced from at least 2 wt% to Ca²⁺And SO₄ ^2-And then the SO in the mixed slurry is added₄ ^2-From Ca in concentration²⁺And SO₄ ^2-To an equilibrium concentration of at least 3 wt%.

6. Root of herbaceous plantThe method for treating rare earth phosphate ore according to claim 1, wherein the concentration of phosphoric acid in the mixed slurry is P₂O₅The weight percentage is 20wt percent to 50wt percent.

7. The method for treating rare earth phosphate ore according to claim 1, wherein the weight ratio of the phosphoric acid to the rare earth phosphate ore in the mixed slurry is 1: 1-10: 1.

8. the method for treating rare earth phosphate ore according to claim 1, wherein the sum of the weights of Al ion, Fe ion and Si ion in the mixed slurry is controlled to be 0.1-3 wt% in terms of their oxides based on the weight of the rare earth phosphate ore during the heating of the mixed slurry.

9. The method for treating rare earth phosphate ore according to any one of claims 1 to 8, characterized by further comprising the step of adding calcium sulfate seed crystals and/or active additives to the mixed slurry.

10. The method for treating rare earth phosphate ore according to claim 9, wherein the addition amount of the calcium sulfate seed crystal is 0.1-30 wt% of the mass of the rare earth phosphate ore.

11. The method for treating rare earth phosphate ore according to claim 9, wherein the active additive is added in an amount of 0.0001-8 wt% based on the mass of the rare earth phosphate ore.

12. The method for treating rare earth phosphate ore according to claim 9, wherein the active additive is an organic additive and/or an inorganic additive.

13. The method for treating rare earth phosphate ore according to claim 12, wherein the organic additive is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, cetyl trimethyl ammonium bromide, polyacrylamide, polyethylene glycol and polyvinyl alcohol.

14. The method for treating rare earth phosphate ore according to claim 12, wherein the inorganic additive is sodium polyphosphate, (NH)₄)₂SO₄、Na₂SO₄、NaCl、NH₄Cl、NH₄NO₃And NaNO₃One or more of (a).

15. The method for treating rare earth phosphate ore according to claim 12, wherein the inorganic additive is (NH)₄)₂SO₄。

16. The method for treating rare earth phosphate ore according to any one of claims 1 to 8, wherein the hemihydrate gypsum is recrystallized SO in solution₄ ^2-The concentration of (A) is 3 wt% -15 wt%.

17. The method of any one of claims 1 to 8, further comprising filtering the liquid of the hemihydrate gypsum after recrystallization and adding a portion of the filtered filtrate back to the solution of the hemihydrate gypsum after recrystallization.

18. A method for enriching rare earth from rare earth phosphorite is characterized by comprising the following steps: treating rare earth phosphate ore according to the method of any one of claims 1 to 16; then recovering rare earth elements from the liquid obtained after the semi-hydrated gypsum is recrystallized.

19. The method for enriching rare earth from rare earth phosphorite as claimed in claim 18, wherein the recovery of rare earth elements from the liquid after the recrystallization of the hemihydrate gypsum is as follows: recovering rare earth elements by adopting a neutralization precipitation method; or extracting and recovering radioactive elements and other rare earth elements in the liquid by using a solvent; or evaporating and concentrating the liquid to obtain the rare earth phosphate.

20. A method for enriching rare earth from rare earth phosphorite is characterized by comprising the following steps: treating rare earth phosphate ore according to the method of any one of claims 1 to 17; then, the rare earth element is recovered from the liquid obtained by heating the mixed slurry.