A method for comprehensive recovery of rare earth and iron from rare earth ore with high iron content

Abstract

The present invention provides a method for comprehensive recovery of rare earth and iron from rare earth ores with high iron content, and relates to the technical field of hydrometallurgy. The present invention mixes the ore powder of the rare earth ore with high iron content with concentrated sulfuric acid, and then roasts it after pre-ripening, so as to have a high decomposition rate of the minerals in the ore and improve the extraction rate of the target element; the present invention adopts a sulfuric acid double salt precipitation method to precipitate the rare earth in the rare earth leaching solution obtained after water leaching, so as to effectively separate the rare earth from a large amount of iron elements; the present invention adopts sodium hydroxide to transform the rare earth sulfate double salt and hydrochloric acid to obtain a rare earth chloride solution product; the present invention utilizes the characteristics of high sulfate content and high acidity in the precipitation mother liquor, and controls the iron-sulfur ratio, acidity and hydrolysis temperature in the mother liquor to complete the oxidation and precipitation process of iron at high temperature to generate a relatively pure iron alum enrichment. The present invention realizes the comprehensive recovery of rare earth and iron in the rare earth ore with high iron content, with a total recovery rate of rare earth exceeding 91.2% and a total recovery rate of iron exceeding 72%.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for comprehensively recovering rare earth and iron from rare earth ores with high iron content. Background Art

[0002] Rare earth is a general term for 17 elements, including lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium and scandium, which have similar properties to lanthanide elements. The world is rich in rare earth resources. There are about 169 known rare earth minerals, but only a dozen of them are used by the metallurgical industry. They are mainly bastnaesite, monazite, xenotime, weathering crust leaching ion adsorption type ore, etc. The lowest industrial grade of rare earth primary ore is 1.5% to 2.0%, and it needs to be concentrated and concentrated to obtain rare earth concentrate that meets the smelting requirements. Rare earth concentrates are generally made into various rare earth compound products by acid and alkali enhanced decomposition, leaching, purification, concentration or burning.

[0003] The rare earth grade and impurity content in rare earth concentrate are key factors affecting the rare earth extraction process and efficiency, especially the impurity iron has a great impact on the recovery rate of rare earth. For concentrates with low iron content (iron content <5wt%), a high-temperature enhanced roasting process is generally used to decompose iron sulfate into basic iron sulfate or iron trioxide that is not easily dissolved under high temperature conditions, inhibiting its entry into the leaching solution. However, when the iron content is high, the recovery rate of rare earths will be reduced. For example, for rare earth concentrates with high iron content, Geng Zhiqiang and others from Jiangxi Copper Research Institute have developed a "directional impurity removal technology for impurity iron in rare earth concentrates". By reducing and roasting rare earth concentrates and removing iron by magnetic separation, the iron content in rare earth concentrates is reduced, but it cannot achieve a complete separation of rare earths and iron, and the recovery rate of rare earths still needs to be improved. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for comprehensively recovering rare earth and iron from rare earth ores with high iron content. The method provided by the present invention can achieve efficient separation of rare earth and iron in rare earth ores with high iron content, and the recovery rate of rare earth and iron is high.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for comprehensively recovering rare earth and iron from rare earth ore with high iron content, comprising the following steps:

[0007] (1) mixing ore powder of a rare earth ore with high iron content with concentrated sulfuric acid, pre-cooking and roasting in sequence to obtain roasted clinker; the mass content of iron in the rare earth ore with high iron content is 5 to 20%;

[0008] (2) leaching the roasted clinker in water to obtain rare earth leaching solution and leaching residue through solid-liquid separation;

[0009] (3) mixing the rare earth leaching solution with an alkali metal sulfate to carry out a precipitation reaction, and obtaining a rare earth sulfate double salt precipitate and a precipitation mother liquor through solid-liquid separation;

[0010] (4) washing the rare earth sulfate double salt precipitate and then slurrying, mixing the obtained rare earth sulfate double salt slurry with a sodium hydroxide solution to transform the rare earth double salt, and performing solid-liquid separation to obtain a transformation material and a transformation liquid;

[0011] (5) slurrying the transition material, adjusting the pH value of the transition material slurry to 1-2 with hydrochloric acid for dissolution reaction to obtain a dissolved reaction material; adding the transition material to the dissolved reaction material to adjust the pH value of the dissolved reaction material to 4-4.5 for boiling reaction, and obtaining a rare earth chloride solution product through solid-liquid separation;

[0012] (6) subjecting the precipitation mother liquor or the precipitation mother liquor after adjustment to high temperature oxidation-precipitation reaction under the condition of introducing oxygen, and obtaining an iron alum concentrate by solid-liquid separation; the hydrogen ion concentration in the precipitation mother liquor or the adjusted precipitation mother liquor is 0.8-1.5 mol / L, and the molar concentration ratio of iron ion to sulfate ion is 0.1-0.4:1; the temperature of the high temperature oxidation-precipitation reaction is 200-280° C.;

[0013] (7) calcining the iron alum concentrate to obtain an iron oxide product;

[0014] There is no time limit for step (4) and step (6).

[0015] Preferably, in the step (1), the mass content of rare earth oxides in the rare earth ore with high iron content is 5-40%; the mass fraction of concentrated sulfuric acid is 92-98%, and the mass ratio of the ore powder to concentrated sulfuric acid is 1:0.8-1.2.

[0016] Preferably, the pre-ripening temperature in step (1) is 40-60°C, and the holding time is 0.5-2h; the roasting temperature is 180-250°C, and the roasting includes a curing stage and a aging stage performed sequentially; the material is turned over once every 5-10 minutes during the curing stage, and the total number of turning overs is 3-6 times; the reaction time of the aging stage is 4-5h.

[0017] Preferably, in the step (2), the mass ratio of the roasted clinker to the water used for water immersion is 1:1.8-3.5; the temperature of the water immersion is 20-60°C, and the time is 0.5-4h.

[0018] Preferably, when mixing with alkali metal sulfate in step (3), the temperature of the rare earth leaching solution is 60-80°C; the mass ratio of the rare earth leaching solution to the alkali metal sulfate is 4.5-12:1; the temperature of the precipitation reaction is 90-98°C, and the time is 0.5-2h.

[0019] Preferably, the detergent used for washing in step (4) is a sodium sulfate aqueous solution, the mass fraction of the sodium sulfate aqueous solution is 5-20%; the washing is displacement washing, the displacement washing is 3-6 stages of countercurrent washing, the washing ratio of each stage is 0.3-1.5:1, and the washing temperature is 75-80°C.

[0020] Preferably, the mass concentration of the sodium hydroxide solution in step (4) is 15-25%; the mass of the sodium hydroxide in the sodium hydroxide solution is 35-45% of the mass of the rare earth sulfate double salt; the temperature of the rare earth double salt transformation is 90-100° C., and the time is 1-3 hours.

[0021] Preferably, the concentration of hydrochloric acid in step (5) is 10-12 mol / L; the temperature of the dissolution reaction is 90-100° C., and the time is 0.5-2 h; and the time of the boiling reaction is 1-2 h.

[0022] Preferably, the oxygen partial pressure of the high temperature oxidation-precipitation reaction in step (6) is 0.2-1.0 MPa, and the reaction time is 0.5-4 h.

[0023] Preferably, the calcination temperature in step (7) is 850-1100° C. and the calcination time is 2-4 hours.

[0024] The invention provides a method for comprehensively recovering rare earth and iron from rare earth ore with high iron content. The invention mixes ore powder of rare earth ore with concentrated sulfuric acid, pre-ripens and then roasts. The method of high-temperature acidolysis with concentrated sulfuric acid has strong applicability to minerals in the ore and high decomposition rate, can improve the extraction rate of target elements, and can also effectively reduce the decomposition and volatilization of sulfuric acid, and reduce the amount of sulfuric acid used. The invention mixes the rare earth leachate obtained after water leaching with alkali metal sulfate for precipitation reaction, and adopts a sulfuric acid double salt precipitation method to separate the rare earth in the leachate, thereby avoiding the disadvantage of high acidity requirement in the solution for separating rare earth by neutralization-extraction, oxalic acid precipitation and the like, and at the same time realizes separation of a large amount of rare earth from the solution. Effective separation of iron element; the present invention uses sodium hydroxide to transform rare earth sulfate complex salt, which can react to generate sodium hydroxide rare earth with lower solubility; the present invention uses hydrochloric acid to adjust the pH value of the obtained transformation material slurry to 1-2, which can improve the dissolution rate of rare earth, and then adds the transformation material to adjust the pH, and then hydrolyzes and precipitates the dissolved impurities into the slag to achieve effective separation of rare earth; the present invention utilizes the characteristics of high sulfate content and high acidity in the precipitation mother liquor, controls the iron-sulfur ratio, acidity and temperature in the mother liquor, completes the oxidation and precipitation process of iron under high temperature conditions, generates a relatively pure iron alum enrichment, achieves efficient separation of iron, and also reduces the sulfate concentration in the mother liquor. The method provided by the present invention has strong adaptability to rare earth ores, and is not only applicable to rare earth concentrates, but also to rare earth-containing polymetallic ores. The present invention overcomes the technical difficulties of incomplete separation of iron and rare earth and low recovery rates of rare earth and iron in existing processes, and realizes efficient comprehensive recovery of rare earth and iron in rare earth ores with high iron content, thereby reducing metallurgical costs. The method provided by the present invention has a total recovery rate of rare earths of more than 91.2% and a total recovery rate of iron of more than 72% in rare earth ores with high iron content. DETAILED DESCRIPTION

[0025] The present invention provides a method for comprehensively recovering rare earth and iron from rare earth ore with high iron content, comprising the following steps:

[0026] (1) mixing ore powder of a rare earth ore with high iron content with concentrated sulfuric acid, pre-cooking and roasting in sequence to obtain roasted clinker; the mass content of iron in the rare earth ore with high iron content is 5 to 20%;

[0027] (2) leaching the roasted clinker in water to obtain rare earth leaching solution and leaching residue through solid-liquid separation;

[0028] (3) mixing the rare earth leaching solution with an alkali metal sulfate to carry out a precipitation reaction, and obtaining a rare earth sulfate double salt precipitate and a precipitation mother liquor through solid-liquid separation;

[0029] (4) washing the rare earth sulfate double salt precipitate and then slurrying, mixing the obtained rare earth sulfate double salt slurry with a sodium hydroxide solution to transform the rare earth double salt, and performing solid-liquid separation to obtain a transformation material and a transformation liquid;

[0030] (5) slurrying the transition material, adjusting the pH value of the transition material slurry to 1-2 with hydrochloric acid for dissolution reaction to obtain a dissolved reaction material; adding the transition material to the dissolved reaction material to adjust the pH value of the dissolved reaction material to 4-4.5 for boiling reaction, and obtaining a rare earth chloride solution product through solid-liquid separation;

[0031] (6) subjecting the precipitation mother liquor or the precipitation mother liquor after adjustment to high temperature oxidation-precipitation reaction under the condition of introducing oxygen, and obtaining an iron alum concentrate by solid-liquid separation; the hydrogen ion concentration in the precipitation mother liquor or the adjusted precipitation mother liquor is 0.8-1.5 mol / L, and the molar concentration ratio of iron ion to sulfate ion is 0.1-0.4:1; the temperature of the high temperature oxidation-precipitation reaction is 200-280° C.;

[0032] (7) calcining the iron alum concentrate to obtain an iron oxide product;

[0033] There is no time limit for step (4) and step (6).

[0034] The present invention mixes the ore powder of the rare earth ore with high iron content with concentrated sulfuric acid, performs pre-mature processing and roasting in sequence, and obtains roasted clinker. In the present invention, the mass content of iron in the rare earth ore with high iron content is 5-20%, preferably 13.5-14.5%, and the mass content of rare earth oxide in the rare earth ore with high iron content is preferably 5-40%, more preferably 21-30%. The present invention has no special requirements for the source of the rare earth ore with high iron content, and the rare earth ores with high iron content well known to those skilled in the art are suitable for the present invention. The present invention has strong adaptability to rare earth ores, and is not only suitable for rare earth concentrates, but also for rare earth-containing polymetallic ores. In the present invention, the water content of the ore powder of the rare earth ore with high iron content is preferably less than 0.5wt%. When the water content of the ore powder is greater than or equal to 0.5wt%, it can be dried to make its water content reach the requirement of less than 0.5wt%. In the present invention, the mass fraction of the concentrated sulfuric acid is preferably 92-98%, more preferably 98%; the mass ratio of the mineral powder to the concentrated sulfuric acid is preferably 1:0.8-1.2, specifically 1:0.8, 1:0.9, 1:1.2; the present invention has no special requirements for the method of mixing the mineral powder with the concentrated sulfuric acid, as long as the mixing is uniform. In the present invention, the pre-ripening temperature is preferably 40-60°C, and the insulation time is preferably 0.5-2h, more preferably 0.5-1h; the reaction heat after the mineral powder and the concentrated sulfuric acid are mixed can reach a temperature of 40-60°C, that is, the pre-ripening does not require additional heating. Through the pre-ripening, the present invention can, on the one hand, fully infiltrate the concentrated sulfuric acid with the mineral powder particles, infiltrate the concentrated sulfuric acid into the mineral powder particles, and contact the target mineral inside the mineral particles; on the other hand, it can react with the reactive substances in the ore, such as some carbonates, sulfide minerals, etc., so that the generated carbon dioxide, sulfide, etc. are slowly released, and the temperature is directly increased to prevent the gas from escaping quickly and taking away too much concentrated sulfuric acid, resulting in excessive loss of reagents.

[0035] In the present invention, the calcination temperature is preferably 180-250°C, more preferably 180-230°C; the calcination is preferably carried out in a muffle furnace or a high temperature box. In the present invention, the calcination preferably includes a solidification stage and a maturation stage carried out in sequence; the solidification stage is preferably turned over once every 5-10 minutes, and the total number of turning overs is preferably 3-6 times; the reaction time of the maturation stage is preferably 4-5 hours. In the solidification stage, the slurry mixed with the ore powder and concentrated sulfuric acid is mainly made to quickly form solid particles at high temperature, and the appropriate turning method can effectively solve the problem of material agglomeration, and at the same time form particles with uniform particles and a particle size of no more than 15mm, which is convenient for the rapid decomposition of the roasted clinker in the water immersion stage; in the maturation stage, the concentrated sulfuric acid reacts with difficult-to-decompose minerals, such as xinganshi, monazite, ilmenite, magnetite, etc., so that the minerals are fully decomposed and the dissolution rate of rare earth and iron is increased.

[0036] After obtaining the roasted clinker, the present invention soaks the roasted clinker in water, and obtains rare earth leaching solution and leaching residue through solid-liquid separation. In the present invention, the mass ratio of the roasted clinker to the water used for water soaking is preferably 1:1.8-3.5, more preferably 1:1.85-2; the temperature of the water soaking is preferably 20-60°C, more preferably 40-50°C, and the time is preferably 0.5-4h, more preferably 1.5-2h. The present invention has no special requirements for the solid-liquid separation method, and a solid-liquid separation method well known to those skilled in the art can be used. The present invention also preferably washes the obtained leaching residue, and the washing is preferably countercurrent washing, the number of washing stages is preferably 3-5 stages, more preferably 3-4 stages, and the washing ratio of each stage is preferably 0.5-1.0:1, more preferably 0.5-0.6:1; in the process of the countercurrent washing, the first-stage water washing liquid is preferably combined with the leaching liquid, and the second-stage water washing liquid is preferably used as the first-stage washing water in the next cycle, and so on. In the present invention, the washing rate of the rare earth in the leached residue by water washing is above 98%, and the loss of rare earth is reduced by water washing.

[0037] After obtaining the leachate, the present invention mixes the rare earth leachate with an alkali metal sulfate for precipitation reaction, and obtains a rare earth sulfate double salt precipitate and a precipitation mother liquor through solid-liquid separation. In the present invention, the alkali metal sulfate is preferably sodium sulfate; when mixed with the alkali metal sulfate, the temperature of the rare earth leachate is preferably 60 to 80°C, specifically, the rare earth leachate is heated to 60 to 80°C, and then the alkali metal sulfate is added thereto. In the present invention, the mass ratio of the rare earth leachate to the alkali metal sulfate is preferably 4.5 to 12:1, more preferably 8 to 10:1; the temperature of the precipitation reaction is preferably 90 to 98°C, more preferably 95°C, and the time is preferably 0.5 to 2h, more preferably 1.5h. During the precipitation reaction, the rare earth sulfate in the rare earth leachate (the rare earth in the rare earth ore mainly exists in the form of rare earth sulfate), especially the light rare earth sulfate, can react with the alkali metal sulfate to form a stable rare earth sulfate complex salt and precipitate. Taking the alkali metal sulfate as sodium sulfate as an example, the reaction formula involved is shown in Formula A (in Formula A, RE represents rare earth). In view of the characteristics of high acid and high iron in the leachate, the present invention adopts a sulfate complex salt precipitation method for precipitation, and the precipitation rate of rare earth is more than 95.2%, while the precipitation rate of iron is less than 3%, thereby realizing efficient separation of rare earth and iron.

[0038] xR 2 (SO 4 ) 3 +yNa 2 SO 4 +zH 2 O=xRE 2 (SO 4 ) 3 ·yNa 2SO 4 ·zH 2 O formula A.

[0039] After obtaining the rare earth sulfate double salt precipitate and the precipitate mother liquor, the present invention processes the rare earth sulfate double salt precipitate and the precipitate mother liquor respectively, specifically as follows:

[0040] The present invention washes the rare earth sulfate double salt precipitate and then makes pulp, mixes the obtained rare earth sulfate double salt slurry with sodium hydroxide solution to transform the rare earth double salt, and obtains transformation material and transformation liquid through solid-liquid separation. In the present invention, the detergent used in the washing is preferably an aqueous sodium sulfate solution, and the mass fraction of the aqueous sodium sulfate solution is preferably 5-20%, more preferably 10-15%; the present invention uses an aqueous sodium sulfate solution to wash the rare earth sulfate double salt precipitate, which can reduce the rare earth dissolution loss during the washing process. In the present invention, the washing is preferably displacement washing, and the displacement washing is preferably 3-6 stage countercurrent washing, more preferably 4-5 stage countercurrent washing, and the washing ratio of each stage is preferably 0.3-1.5:1, more preferably 1.3-1.5:1, and the washing temperature is preferably 75-80°C, more preferably 80°C. The present invention adopts a sodium sulfate aqueous solution heating countercurrent washing method, which has the advantages of low rare earth elution rate and high elution rate of impurities such as acid; the washing has an elution rate of less than 2.0% for rare earth in rare earth sulfate double salt precipitation, and an elution rate of greater than or equal to 94.8% for acid in rare earth sulfate double salt precipitation. The present invention has no special requirements for the pulping method, and the washed rare earth sulfate double salt precipitation can be made into slurry with water using a pulping method well known to those skilled in the art; the solid content of the slurry is preferably 35-50wt%. In the present invention, the mass concentration of the sodium hydroxide solution is preferably 15-25%, more preferably 20-22%; the mass of sodium hydroxide in the sodium hydroxide solution is preferably 35-45% of the mass of the rare earth sulfate double salt, more preferably 40-42%. In the present invention, the temperature of the transformation of the rare earth double salt is preferably 90-100°C, more preferably 95°C, and the time is preferably 1-3h, more preferably 1.5-2h. In the process of rare earth double salt transformation, rare earth sulfate double salt reacts with concentrated alkali to generate rare earth hydroxide with lower solubility (i.e., transformation material), while sodium sulfate and some impurities such as calcium are transferred into the transformation liquid, which is then separated by solid-liquid separation; the reaction formula involved in the transformation of rare earth double salt is shown in Formula B:

[0041] RE 2 (SO 4 ) 3 ·Na 2 SO 4 +6NaOH=2RE(OH) 3(S) +4Na 2 SO 4 Formula B.

[0042] After obtaining the transformation material, the present invention pulps the transformation material, uses hydrochloric acid to adjust the pH value of the obtained transformation material slurry to 1-2 for dissolution reaction, and obtains a dissolution reaction material; adds the transformation material to the dissolution reaction material to adjust the pH value of the dissolution reaction material to 4-4.5 for boiling reaction, and obtains a rare earth chloride solution product through solid-liquid separation. In the present invention, the concentration of the hydrochloric acid is preferably 10-12 mol / L; the temperature of the dissolution reaction is preferably 90-100°C, more preferably 95°C, the time is preferably 0.5-2h, and the dissolution reaction is preferably carried out under stirring. In the present invention, the boiling reaction time is preferably 1-2h, more preferably 2h. The present invention adjusts the pH value of the transition material slurry to 1-2 in order to improve the dissolution rate of rare earths. However, when the rare earth dissolution rate is improved, the dissolution of impurities such as iron, uranium and thorium will also be increased. Then, by adding the transition material to adjust the pH value and boiling, the dissolved impurities can be hydrolyzed and precipitated into the slag, thereby achieving effective separation of the rare earths. A qualified rare earth chloride solution product (meeting the product quality standard: GB / T4148-2015 "Mixed Rare Earth Chloride") can be obtained through solid-liquid separation.

[0043] The present invention uses the precipitation mother liquor or adjusts the precipitation mother liquor, and then conducts a high-temperature oxidation-precipitation reaction under the condition of introducing oxygen, and obtains an iron alum concentrate through solid-liquid separation. In the present invention, the hydrogen ion concentration in the precipitation mother liquor or the adjusted precipitation mother liquor is 0.8-1.5 mol / L, preferably 0.8-1.2 mol / L, and the molar concentration ratio of iron ions to sulfate ions is 0.1-0.4:1, preferably 0.1-0.21:1. In the present invention, the adjustment reagent used in the adjustment preferably includes NaOH, Na 2 CO 3 , ammonia, CaO, CaCO 3 and Ca(OH) 2 One or more of the following, wherein NaOH, Na 2 CO 3 and ammonia water to adjust the hydrogen ion concentration in the precipitation mother liquor, using CaO, CaCO 3 and Ca(OH) 2One or more of the above are used to adjust the sulfate ion concentration in the precipitation mother liquor, and the concentration is specifically selected according to the ion content in the precipitation mother liquor, so as to meet the requirements of the hydrogen ion concentration and the molar concentration ratio of iron ions to sulfate ions; when the precipitation mother liquor has met the requirements of the hydrogen ion concentration and the molar concentration ratio of iron ions to sulfate ions, no adjustment is required, and the high-temperature oxidation-precipitation reaction is directly carried out. In the present invention, the temperature of the high-temperature oxidation-precipitation reaction is preferably 200-280°C, more preferably 200-230°C; the oxygen partial pressure of the high-temperature oxidation-precipitation reaction is preferably 0.2-1.0MPa, more preferably 0.85-1.0MPa, and the reaction time is preferably 0.5-4h, more preferably 1-2h; the high-temperature oxidation-precipitation reaction is specifically carried out in a pressurized reactor.

[0044] The existing hematite precipitation method generally precipitates iron under conditions of relatively low acidity and sulfate concentration to produce hematite (Fe 2 O 3 ), its acidity is generally controlled at 0.01-0.8 mol / L, and the iron content in the solution after iron removal is 1-5 g / L. Since the sulfate concentration in the solution is relatively low, the sulfur content of the hematite generally generated is below 1 wt%. The present invention utilizes the characteristics of the research object, that is, the high sodium content, high acidity, and high sulfate concentration in the precipitation mother liquor, and controls the acidity, iron and sulfate concentrations, and then achieves oxidation and precipitation of iron in the solution in one step through high-temperature oxidation (also known as high-temperature enhanced oxidation), so that the iron is generated in the form of a relatively pure iron alum enrichment (complex compound containing Na, iron, and sulfur, the possible composition is Na 2 Fe 6 (SO 4 ) x (OH) y ) is precipitated, thereby further reducing the sulfate concentration in the solution while recovering iron, and it can be returned to the water leaching process; and the iron alum enrichment generated at high temperature (200-280°C) has the advantage of low water content, which can reduce the subsequent precipitate slag washing and calcination consumption.

[0045] After the high-temperature oxidation-precipitation reaction, the iron ion concentration in the precipitation mother liquor is reduced to below 150 mg / L, and the iron recovery rate in the solution is above 96.7%; and the iron alum concentrate is obtained through solid-liquid separation.

[0046] After obtaining the iron alum concentrate, the present invention calcines the iron alum concentrate to obtain an iron oxide product. In the present invention, the calcination temperature is preferably 850-1100°C, more preferably 1000°C, the time is preferably 2-4h, more preferably 2h; the calcination is preferably carried out in a muffle furnace. After the calcination, the iron alum concentrate is converted into an iron oxide product.

[0047] The present invention overcomes the technical difficulties of incomplete separation of iron and rare earth and low recovery rate of rare earth and iron in the existing process for treating rare earth ores with high iron content, realizes the comprehensive recovery of rare earth and iron in rare earth ores with high iron content, and reduces metallurgical costs.

[0048] The method for comprehensive recovery of rare earth and iron from high iron content rare earth ore provided by the present invention is described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0049] Example 1

[0050] A rare earth concentrate containing minerals such as yttrium silicate, bastnaesite, monazite, etc., with a rare earth oxide content of 30wt% and a total iron content of 14.5wt%.

[0051] S1. Take 200g of the above concentrate powder and 98wt% concentrated sulfuric acid, mix them evenly in a mass ratio of ore to acid of 1:0.8, and pre-mature for 0.5h after mixing evenly.

[0052] S2. Set the temperature of the muffle furnace to 180°C. After the furnace temperature is constant, put the pre-matured material into the muffle furnace and turn the material over every 10 minutes. After turning the material over three times, the slurry is completely solidified and no more turning is performed. Continue to react at this temperature for 5 hours to obtain the roasted clinker.

[0053] S3. Grind the roasted clinker and mix it with clean water, the mass ratio of clean water to clinker is 3.5:1, the reaction temperature is 60°C, and the reaction is carried out for 1.5 hours; after the leaching is completed, the solid-liquid separation is carried out to obtain rare earth leaching solution and leaching residue, and the leaching residue is countercurrent washed, the washing ratio is 0.5:1, the washing stage number is 3 (the first stage water washing liquid is combined with the leaching liquid), and the rare earth washing rate is 98.2%.

[0054] S4. Heat the rare earth leaching solution to 60°C, add sodium sulfate at a mass ratio of 4.5:1 between the rare earth leaching solution and sodium sulfate, and heat at 95°C for 1.5h; obtain rare earth sulfate complex salt precipitate and precipitate mother liquor through solid-liquid separation; the rare earth precipitation rate is 98.2%, and the iron precipitation rate is <3%.

[0055] S5. The rare earth sulfate double salt precipitate is subjected to displacement washing, and a 10% by mass sodium sulfate solution is used as a detergent. The washing conditions are: 5-stage countercurrent washing, a washing ratio of 1.3:1 in each stage, and a washing water temperature of 80°C. During the washing process, the rare earth washing rate in the rare earth double salt is <1.3%, and the acid washing rate is ≥97.5%.

[0056] S6. The washed rare earth sulfate complex salt is pulped and transformed using a NaOH solution (concentration of 22 wt%), wherein the mass of NaOH in the NaOH solution is 42% of the mass of the rare earth sulfate complex salt, and the reaction is carried out at 95° C. for 2 h; after the transformation, the solid and liquid are separated to obtain a transformation material and a transformation liquid.

[0057] S7. Slurry the transformation material with clean water, adjust the pH to 1 with 12 mol / L hydrochloric acid, stir and heat to 95°C for dissolution reaction; then add the transformation material to adjust the pH to 4, boil and react for 2 hours; after the reaction is completed, perform solid-liquid separation to prepare a qualified rare earth chloride solution product (total rare earth recovery rate 91.2%).

[0058] S8, adjust the precipitate mother solution, solution C H+ =0.8mol / L, C Fe :C (SO4)2- =0.1:1; add the adjusted solution into a pressure reactor and heat to 200°C; introduce oxygen and react for 1 hour at an oxygen partial pressure of 1.0 MPa; after the reaction is completed, separate the solid and liquid to obtain an iron-enriched product (iron alum-enriched product). The iron recovery rate in the solution is 96.7%.

[0059] S9. Put the iron-enriched material into a muffle furnace and calcine it at 1000° C. for 2 hours to prepare an iron oxide product.

[0060] Example 2

[0061] A rare earth flotation concentrate containing niobium iron ore, yttrium silicate, fluorocarbon cerium and other minerals, the rare earth oxide content of the concentrate is 5wt%, the total iron content is 20wt%, and the niobium content is 3.5wt%.

[0062] S1. Take 200g of the above concentrate powder and 98wt% concentrated sulfuric acid, mix them evenly in a mass ratio of 1:1.2 between ore and acid, and pre-mature them for 1h after mixing evenly;

[0063] S2. Set the temperature of the muffle furnace to 230°C. After the furnace temperature is constant, put the pre-matured material into the muffle furnace and turn the material over every 8 minutes. After turning the material over 5 times, the slurry is completely solidified and no more turning is performed. Continue to react at this temperature for 5 hours to obtain the roasted clinker.

[0064] S3. Grind the roasted clinker and mix it with clean water, the mass ratio of clean water to clinker is 1.85:1, the reaction temperature is 40°C, and the reaction is carried out for 2 hours; after the leaching is completed, the solid-liquid separation is carried out to obtain rare earth leaching solution and leaching residue, and the leaching residue is countercurrent washed, the washing ratio is 0.6:1, the washing stage number is 4 (the first stage water washing liquid is combined with the leaching liquid), and the rare earth washing rate is 98.7%.

[0065] S4. Heat the rare earth leaching solution to 75°C, add sodium sulfate in a mass ratio of 8:1 between the rare earth leaching solution and sodium sulfate, and heat at 95°C for 1.5h; obtain rare earth sulfate complex salt precipitate and precipitate mother liquor through solid-liquid separation; the rare earth precipitation rate is 95.2%, and the iron precipitation rate is <2.8%.

[0066] S5. The rare earth sulfate double salt precipitate is subjected to displacement washing, and a 15% by mass sodium sulfate solution is used as a detergent. The washing conditions are: 4-stage countercurrent washing, a washing ratio of 1.5:1 in each stage, and a washing water temperature of 75°C. During the washing process, the rare earth washing rate in the rare earth sulfate double salt is <1.5%, and the acid washing rate is ≥94.8%.

[0067] S6. The washed rare earth sulfate double salt is pulped and transformed using a NaOH solution (concentration 20 wt%), the mass of NaOH in the NaOH solution is 40% of the mass of the rare earth sulfate double salt, and the reaction is carried out at 95° C. for 1.5 h; after the transformation, the solid and liquid are separated to obtain a transformation material and a transformation liquid.

[0068] S7. Slurry the transformation material with clean water, adjust the pH to 1 with 12 mol / L hydrochloric acid, stir and heat to 95°C for dissolution reaction; then add the transformation material to adjust the pH to 4, boil and react for 2 hours; after the reaction is completed, perform solid-liquid separation to prepare a qualified rare earth chloride solution product (total rare earth recovery rate 91.3%).

[0069] S8, adjust the rare earth double salt precipitation mother solution, solution C H+ =1.2mol / L, C Fe :C (SO4)2- =0.18:1; add the adjusted solution into a pressure reactor and heat to 210°C; introduce oxygen and react for 1 hour at an oxygen partial pressure of 1.0 MPa; after the reaction is completed, separate the solid and liquid to obtain an iron-enriched product. The iron recovery rate in the solution is 97.8%.

[0070] S9. Put the iron-enriched material into a muffle furnace and calcine it at 1000° C. for 2 hours to prepare an iron oxide product.

[0071] Example 3

[0072] A rare earth concentrate containing minerals such as monazite and bastnaesite, the rare earth oxide content of the concentrate is 21wt%, and the total iron content is 13.5wt%.

[0073] S1. Take 200g of the above concentrate powder and 98wt% concentrated sulfuric acid, mix them evenly according to the mass ratio of ore to acid of 1:0.9, and pre-mature for 2h after mixing evenly;

[0074] S2. Set the temperature of the muffle furnace to 250°C. After the furnace temperature is constant, put the pre-matured material into the muffle furnace and turn the material over every 6 minutes. After turning the material over 5 times, the slurry is completely solidified and no more turning is performed. Continue to react at this temperature for 4 hours to obtain the roasted clinker.

[0075] S3. Grind the roasted clinker and mix it with clean water, the mass ratio of clean water to clinker is 2:1, the reaction temperature is 50°C, and the reaction is carried out for 2 hours; after the leaching is completed, the solid-liquid separation is carried out to obtain rare earth leaching solution and leaching residue, and the leaching residue is countercurrent washed, the washing ratio is 1:1, the washing stage number is 4 (the first stage water washing liquid is combined with the leaching liquid), and the rare earth washing rate is 98.3%.

[0076] S4. Heat the rare earth leaching solution to 60°C, add sodium sulfate in a mass ratio of 10:1 between the rare earth leaching solution and sodium sulfate, and heat at 95°C for 1.5h; obtain rare earth sulfate complex salt precipitate and precipitate mother liquor through solid-liquid separation; the rare earth precipitation rate is 98.5%, and the iron precipitation rate is <3%.

[0077] S5. The rare earth sulfate double salt precipitate is subjected to displacement washing, and a 20% by mass sodium sulfate solution is used as a detergent. The washing conditions are: 4-stage countercurrent washing, a washing ratio of 1.2:1 in each stage, and a washing water temperature of 80°C. During the washing process, the rare earth washing rate in the rare earth sulfate double salt is <2.0%, and the acid washing rate is ≥97.5%.

[0078] S6. The washed rare earth sulfate complex salt is pulped and transformed using a NaOH solution (concentration 15 wt%), wherein the mass of NaOH in the NaOH solution is 45% of the mass of the rare earth sulfate complex salt, and the reaction is carried out at 95° C. for 2 h; after the transformation, the solid and liquid are separated to obtain a transformation material and a transformation liquid.

[0079] S7. Slurry the transformation material with clean water, adjust the pH to 2 with 10 mol / L hydrochloric acid, stir and heat to 95°C for dissolution reaction; then add the transformation material to adjust the pH to 4, boil and react for 2 hours; after the reaction is completed, perform solid-liquid separation to prepare a qualified rare earth chloride solution product (total rare earth recovery rate 92.5%).

[0080] S8, adjust the rare earth double salt precipitation mother solution, solution C H+ =0.8mol / L, C Fe :C (SO4)2- =0.21:1; add the adjusted solution into a pressure reactor and heat to 230°C; introduce oxygen and react for 2 hours at an oxygen partial pressure of 0.85MPa; after the reaction is completed, separate the solid and liquid to obtain an iron-enriched product. The iron recovery rate in the solution is 98.1%.

[0081] S9. Put the iron-enriched material into a muffle furnace and calcine it at 1000° C. for 2 hours to prepare an iron oxide product.

[0082] It can be seen from the above embodiments that the present invention overcomes the technical difficulties of incomplete separation of iron and rare earth and low recovery rate of rare earth and iron in the existing process, and realizes the efficient comprehensive recovery of rare earth and iron in high-iron content rare earth ores.

[0083] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for comprehensive recovery of rare earth and iron from rare earth ores with high iron content, It is characterized in that The following steps are involved: (1) mixing ore powder of a high-iron-content rare earth ore with concentrated sulfuric acid, pre-cooking and roasting in sequence to obtain roasted clinker; the mass content of iron in the high-iron-content rare earth ore is 5-20%, and the mass content of rare earth oxide is 5-40%; the roasting temperature is 180-230° C.; (2) leaching the roasted clinker in water to obtain rare earth leaching solution and leaching residue through solid-liquid separation; (3) mixing the rare earth leaching solution with an alkali metal sulfate to carry out a precipitation reaction, and obtaining a rare earth sulfate double salt precipitate and a precipitation mother liquor through solid-liquid separation; (4) washing the rare earth sulfate double salt precipitate and then slurrying, mixing the obtained rare earth sulfate double salt slurry with a sodium hydroxide solution to transform the rare earth double salt, and performing solid-liquid separation to obtain a transformation material and a transformation liquid; (5) slurrying the transition material, adjusting the pH value of the obtained transition material slurry to 1-2 with hydrochloric acid for dissolution reaction to obtain a dissolved reaction material; adding the transition material to the dissolved reaction material to adjust the pH value of the dissolved reaction material to 4-4.5 for boiling reaction, and obtaining a rare earth chloride solution product through solid-liquid separation; (6) subjecting the precipitation mother liquor or the adjusted precipitation mother liquor to a high-temperature oxidation-precipitation reaction under the condition of introducing oxygen, and obtaining an iron alum concentrate by solid-liquid separation; the hydrogen ion concentration in the precipitation mother liquor or the adjusted precipitation mother liquor is 0.8-1.5 mol / L, and the molar concentration ratio of iron ion to sulfate ion is 0.1-0.4:1; the temperature of the high-temperature oxidation-precipitation reaction is 200-280° C.; (7) calcining the iron alum concentrate to obtain an iron oxide product; There is no time limit for step (4) and step (6).

2. The method according to claim 1, It is characterized in that The mass fraction of concentrated sulfuric acid in step (1) is 92-98%, and the mass ratio of the mineral powder to concentrated sulfuric acid is 1:0.8-1.

2.

3. The method according to claim 1 or 2, It is characterized in that The pre-ripening temperature in step (1) is 40-60° C., and the holding time is 0.5-2 h. The roasting includes a curing stage and a aging stage, which are carried out in sequence. The material is turned over once every 5-10 minutes during the curing stage, and the total number of turning overs is 3-6 times. The reaction time of the aging stage is 4-5 h.

4. The method according to claim 1, It is characterized in that In the step (2), the mass ratio of the roasted clinker to the water used for water immersion is 1:1.8-3.5; the temperature of the water immersion is 20-60°C, and the time is 0.5-4h.

5. The method according to claim 1, It is characterized in that When mixing with alkali metal sulfate in step (3), the temperature of the rare earth leaching solution is 60-80°C; the mass ratio of the rare earth leaching solution to the alkali metal sulfate is 4.5-12:1; the temperature of the precipitation reaction is 90-98°C, and the time is 0.5-2h.

6. The method according to claim 1, It is characterized in that The washing detergent used in step (4) is a sodium sulfate aqueous solution, the mass fraction of which is 5-20%; the washing is displacement washing, which is 3-6 stages of countercurrent washing, the washing ratio of each stage is 0.3-1.5:1, and the washing temperature is 75-80°C.

7. The method according to claim 1, It is characterized in that The mass concentration of the sodium hydroxide solution in step (4) is 15-25%; the mass of the sodium hydroxide in the sodium hydroxide solution is 35-45% of the mass of the rare earth sulfate double salt; the temperature of the rare earth double salt transformation is 90-100° C., and the time is 1-3 hours.

8. The method according to claim 1, It is characterized in that The concentration of hydrochloric acid in step (5) is 10-12 mol / L; the temperature of the dissolution reaction is 90-100° C., and the time is 0.5-2 h; and the time of the boiling reaction is 1-2 h.

9. The method according to claim 1, It is characterized in that In the step (6), the oxygen partial pressure of the high temperature oxidation-precipitation reaction is 0.2-1.0 MPa, and the reaction time is 0.5-4 h.

10. The method according to claim 1, It is characterized in that The calcination temperature in step (7) is 850-1100° C. and the calcination time is 2-4 hours.