阅读说明：本技术 一种稀土湿法冶炼中除去非稀土杂质的方法 (Method for removing non-rare earth impurities in rare earth hydrometallurgy ) 是由 卢立海 蔡蔚 曾永春 邓思祥 毛友平 魏云 李霞 廖丕勇 于 2021-07-14 设计创作，主要内容包括：本发明公开了一种稀土湿法冶炼中除去非稀土杂质的方法,包括以下步骤：S1、稀土精矿经酸碱联合法处理得到混合氯化稀土液,然后向混合氯化稀土液中加入不影响稀土质量的硫酸根溶液,沉淀过滤后取滤液；S2、采用现有萃取方法对滤液进行萃取分离,得到各类氯化稀土液；S3、取萃取分离得到的氯化镧液于反应槽中,然后升温至80℃以上,向氯化镧液中加入碳酸根溶液,调节溶液的pH值至3.5－4,然后加入硫离子溶液,过滤沉淀后取滤液即得。本发明通过在不增加设备和工艺流程的基础上,萃取前先除去钡镭等重金属杂质,萃取分离后铅杂质得到有效富集,更容易除去,该方式不仅可以有效降低镨钕氧化物的物料损失,而且对铅的去除效果极好,无需进行稀土回收处理,克服了现有技术所存在的不足。(The invention discloses a method for removing non-rare earth impurities in rare earth hydrometallurgy, which comprises the following steps: s1, treating the rare earth concentrate by an acid-base combination method to obtain mixed rare earth chloride solution, adding sulfate radical solution which does not influence the quality of rare earth into the mixed rare earth chloride solution, precipitating and filtering to obtain filtrate; s2, extracting and separating the filtrate by adopting the existing extraction method to obtain various chlorinated rare earth liquids; s3, placing the lanthanum chloride solution obtained by extraction separation into a reaction tank, heating to a temperature above 80 ℃, adding a carbonate solution into the lanthanum chloride solution, adjusting the pH value of the solution to 3.5-4, then adding a sulfur ion solution, filtering and precipitating, and taking a filtrate to obtain the lanthanum chloride. According to the method, on the basis of not increasing equipment and process flow, heavy metal impurities such as barium radium and the like are removed before extraction, lead impurities are effectively enriched and are easily removed after extraction and separation, the material loss of praseodymium and neodymium oxides can be effectively reduced, the lead removal effect is excellent, rare earth recovery treatment is not needed, and the defects in the prior art are overcome.)

1. A method for removing non-rare earth impurities in rare earth hydrometallurgy is characterized by comprising the following steps:

s1, treating the rare earth concentrate by an acid-base combination method to obtain mixed chlorinated rare earth liquid, tempering and concentrating the mixed chlorinated rare earth liquid, then adding a sulfate radical solution which does not influence the quality of rare earth into the mixed chlorinated rare earth liquid, precipitating and filtering, and taking filtrate;

s2, extracting and separating the filtrate by adopting the existing extraction method to obtain various chlorinated rare earth liquids;

s3, putting the lanthanum chloride solution obtained through extraction separation into a reaction tank, heating to a temperature higher than 80 ℃, adding a carbonate solution into the lanthanum chloride solution, adjusting the pH value of the solution to 3.5-4, then adding a sulfur ion solution, filtering and precipitating, and taking a filtrate to obtain the lanthanum chloride solution without the non-rare earth impurity PbO.

2. The method for removing non-rare earth impurities in rare earth hydrometallurgy according to claim 1, wherein a concentration of the mixed chlorinated rare earth liquid obtained by quenching and tempering and concentration is 280 ± 10g/L in S1.

3. The method for removing non-rare earth impurities in rare earth hydrometallurgy according to claim 2, wherein in S1 said sulfate solution is soluble sulfate or sulfuric acid.

4. A method for removing non-rare earth impurities in rare earth hydrometallurgy according to any of claims 1 to 3, wherein the concentration of the lanthanum chloride solution obtained by the extraction separation is controlled to 220 ± 20g/L in S3.

5. The method for removing non-rare earth impurities in rare earth hydrometallurgy according to claim 4, wherein in S3, the carbonate solution is selected from at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

6. The method for removing non-rare earth impurities in rare earth hydrometallurgy according to claim 5, wherein in S3, the sulfur ion solution is sodium sulfide or/and potassium sulfide, and the addition of the sulfur ion solution is stopped when the lead ion content in the solution is less than 0.0025g/L, as an index.

7. The method for removing non-rare earth impurities in rare earth hydrometallurgy according to claim 4, wherein in S2, the types of rare earth chloride liquids include lanthanum chloride liquid, cerium chloride liquid, praseodymium neodymium liquid and samarium europium gadolinium chloride liquid.

8. The method for removing non-rare earth impurities in rare earth hydrometallurgy according to claim 6, wherein in S1 and S3, the filtered residue obtained after filtration is transferred to a dangerous waste storehouse for temporary storage.

Technical Field

The invention relates to the technical field of rare earth hydrometallurgy, in particular to a method for removing non-rare earth impurities in rare earth hydrometallurgy.

Background

At present, rare earth ores produced in Sichuan are bastnaesite, the average grade of the ores is over 65 percent, meanwhile, the components of non-rare earth impurities in the ores are relatively complex, and in order to improve the added value of products and increase the profits of enterprises, the removal of the non-rare earth impurities in rare earth in the process of rare earth hydrometallurgy becomes an important research subject in the process of hydrometallurgy.

In the purification and smelting of rare earth for industrial application, the rare earth raw ore is generally enriched, and most of non-rare earth impurities are removed, for example, bastnaesite raw ore (the grade of bastnaesite of current yak plateau mine is about 1.5%) is enriched by gravity separation and flotation or magnetic separation to obtain bastnaesite with grade of more than 65%, which is herein referred to as rare earth concentrate. The content of PbO in the rare earth concentrate is about 0.4 percent generally, iron and thorium are removed firstly from mixed rare earth chloride, lead and barium radium are removed after concentration, lead removal is performed by chemical precipitation, and lead is removed by sodium sulfide or soluble sulfide generally to form lead sulfide precipitate. However, since the soluble rare earth sulfide is a strong base and a weak acid salt in the lead removing process, the soluble rare earth sulfide is hydrolyzed in the lead removing process, and then rare earth hydroxide, rare earth sulfide and lead sulfide are formed to be coprecipitated so as to bring valuable rare earth into lead sulfide impurities. Through carrying out component detection and analysis on the sediment, 0.8% of rare earth is lost in the formation process of the rare earth sulfide, wherein the part of rare earth has the highest value of praseodymium-neodymium oxide, so that how to reduce the loss of the praseodymium-neodymium oxide to improve the yield of the praseodymium-neodymium oxide and remove the lead impurity is very important.

Chinese patent CN1338526A discloses a method for preparing low-lead low-magnesium mischmetal with alkaline material, which has the following processes: taking a mixed rare earth chloride solution prepared by a caustic soda method as raw material 250-270 g/L, adding an extracting agent to perform Nd-Sm extraction separation to obtain a europium-less mixed rare earth chloride solution, then adding solid ammonium bicarbonate to adjust the pH value to 5-8, taking a precipitate after clarification, washing the precipitate for 1-3 times to obtain a rare earth carbonate precipitate, dissolving the rare earth carbonate precipitate in industrial hydrochloric acid, adding soluble sulfide until the pH value of the rare earth chloride solution reaches 2-6, then filtering to remove a filtrate, and concentrating and crystallizing the filtrate to obtain the europium-less mixed rare earth chloride solution. The patent technology can well remove non-rare earth impurities in rare earth, but as mentioned above, the patent technology directly adds sulfide to precipitate mixed rare earth, which can cause the loss of rare earth elements such as high-value praseodymium and neodymium, and because the loss amount reaches 0.8%, the rare earth recovery treatment of waste residue is still needed, and the economical efficiency is poor.

Chinese patent CN111850296A discloses a method for recovering and preparing high-purity strontium compounds from rare earth ores, which has the following processes: leaching the non-roasted rare earth ore by using a chloride solution to obtain a strontium leaching solution, adding an oxidant into the strontium leaching solution, carrying out solid-liquid separation to obtain a filtrate, adding a sulfide into the filtrate to remove heavy metals, carrying out solid-liquid separation to obtain a filtrate, cooling and crystallizing the filtrate to obtain a crude product, extracting and separating the crude product, and carrying out evaporation and concentration to obtain the high-purity strontium compound. When the high-purity strontium compound is prepared by the patented technology, heavy metals are firstly removed by sulfides, and then extraction and separation are carried out, correspondingly, the mode can cause great loss of rare earth, the waste residue needs to be subjected to rare earth recovery treatment, and the economical efficiency is poor.

Disclosure of Invention

The invention aims to: aiming at the existing problems, the invention provides a method for removing non-rare earth impurities in rare earth wet smelting, on the basis of not increasing equipment and process flow, heavy metal impurities such as barium radium and the like are removed before extraction, and lead impurities are removed after extraction separation.

The technical scheme adopted by the invention is as follows: a method for removing non-rare earth impurities in rare earth hydrometallurgy is characterized by comprising the following steps:

s1, treating the rare earth concentrate by an acid-base combination method to obtain mixed chlorinated rare earth liquid, tempering and concentrating the mixed chlorinated rare earth liquid, then adding a sulfate radical solution which does not influence the quality of rare earth into the mixed chlorinated rare earth liquid, precipitating and filtering, and taking filtrate;

s2, extracting and separating the filtrate by adopting the existing extraction method to obtain various chlorinated rare earth liquids;

s3, placing the lanthanum chloride solution obtained by extraction separation into a reaction tank, heating to above 80 ℃, adding soluble carbonate into the lanthanum chloride solution, adjusting the pH value of the solution to 3.5-4 (in the actual production process, the pH value range with least loss of valuable rare earth is 3.5-4 through trial experiment, and the loss of valuable rare earth is larger if the pH value range is beyond the range), then adding a sulfur ion solution, filtering and precipitating, and taking filtrate to obtain the lanthanum chloride solution with non-rare earth impurities removed.

In the invention, rare earth concentrate is treated by an acid-base combination method to obtain mixed chlorinated rare earth liquid, the mixed chlorinated rare earth liquid is tempered and concentrated, the concentration of lead in the mixed chlorinated rare earth liquid is about 2.5g/L, the existing process is that before extraction and separation are carried out, the mixed chlorinated rare earth liquid is heated, sulfide is added to remove lead, soluble salt containing sulfate radical is added to remove heavy metals such as barium and radium, and finally the mixed chlorinated rare earth liquid is sent into an extraction tank to be extracted and separated, the method can cause about 0.8% of rare earth loss, mainly praseodymium and neodymium loss, in order to improve economic value, rare earth recovery treatment needs to be carried out on waste residue, the rare earth recovery treatment cost is higher, and the economic benefit is not high. For this reason, the inventors have found, in studies for rare earth impurity removal, that since lead is more effective than a lanthanide metal ion, which belongs to a component difficult to extract in a hydrochloric acid organic extraction system, lead ions are finally enriched in raffinate during extraction separation, in a hydrochloric acid organic extraction system of lanthanide rare earth, lanthanum ions belong to raffinate phases, so lead ions are finally enriched in a lanthanum chloride solution, the lanthanum chloride solution obtained through industrial extraction and separation is detected to have the concentration of about 220g/L generally, and the lead concentration in the lanthanum chloride solution is about 3.5g/L, so that, even if heavy metal removal treatment is performed before extraction and separation, the lead content in the lanthanum chloride solution obtained by extraction and separation exceeds the standard (the product-grade lanthanum chloride generally requires that the lead content is not higher than 50ppm), so that the lanthanum chloride needs to be subjected to lead removal treatment, and the treatment effect is poor.

Therefore, in the invention, before extraction separation, sulfate radicals are used for mainly removing heavy metals such as barium and radium from the mixed rare earth solution, then extraction separation is carried out, lead impurities are enriched in a lanthanum chloride solution after extraction separation, lead is precipitated and removed through sulfides, and detection is carried out after precipitation, so that the rare earth content in the obtained lead slag is very low, only 20-40 ppm and mainly lanthanum, the economic benefit of recovery is small, rare earth recovery treatment is not needed, and the lead slag is directly transferred to a dangerous waste storehouse for temporary storage.

Further, in S1, the concentration of the mixed chlorinated rare earth solution obtained by quenching and concentrating was 280. + -.10 g/L. In the actual production process, 280g/L can ensure that the loaded organic phase and the water phase are effectively separated during extraction without generating organic three phases under the condition of keeping the maximum extraction production capacity, and can avoid influencing the extraction effect and efficiency.

Further, in S1, the sulfate solution is soluble sulfate or sulfuric acid. The concentration of the sulfate solution is not specifically required, and the adding amount of the sulfate solution takes the content of barium radium impurities in the solution as an index until the ratio of the barium content to the total amount of the rare earth is less than 0.05%.

Further, in S3, the concentration of the lanthanum chloride solution obtained by extraction and separation was controlled to 220. + -.20 g/L. When the concentration of the feed liquid is about 280g/L, the concentration of the lanthanum chloride solution separated by extraction is about 220 g/L.

Further, in S3, the carbonate solution is at least one selected from sodium carbonate, potassium carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate.

Further, in S3, the sulfur ion solution is sodium sulfide or/and potassium sulfide, and the addition of the sulfur ion solution is stopped when the lead ion content in the solution is less than 0.0025g/L, taking the lead ion content in the solution as an index.

Further, in S2, the various types of rare earth chloride liquids include lanthanum chloride liquid, cerium chloride liquid, praseodymium neodymium liquid, and samarium europium gadolinium chloride liquid.

Further, in S1 and S3, filter residues obtained after filtration are transferred to a dangerous waste storehouse for temporary storage.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that: the method can prevent the loss of the chlorinated rare earth with higher economic value (praseodymium-neodymium), and simultaneously, the rare earth with lower economic value is lost without carrying out the recovery treatment of the rare earth. By adopting the process, the direct yield of the praseodymium-neodymium can be improved by 0.5%, the method can be carried out without increasing equipment and working procedures, the economic benefit can be objectively increased, the production cost can be reduced, and the industrial practicability is high.

Drawings

FIG. 1 is a process flow diagram of the method for removing non-rare earth impurities in rare earth hydrometallurgy.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1 (in fig. 1, SEGCl)₃Liquid represents samarium-europium-gadolinium solution), a method for removing non-rare earth impurities in rare earth hydrometallurgy, comprising the following stepsThe method comprises the following steps:

s1, treating the rare earth concentrate by an acid-base combination method to obtain mixed chlorinated rare earth liquid, tempering and concentrating the mixed chlorinated rare earth liquid, then adding a sulfate radical solution which does not influence the quality of rare earth into the mixed chlorinated rare earth liquid, precipitating and filtering, and taking filtrate;

s2, extracting and separating the filtrate by adopting the existing extraction method to obtain lanthanum chloride liquid, cerium chloride liquid, praseodymium-neodymium chloride liquid and samarium-europium-gadolinium chloride liquid;

s3, placing the lanthanum chloride solution obtained by extraction separation into a reaction tank, heating to a temperature above 80 ℃, adding a carbonate solution into the lanthanum chloride solution, adjusting the pH value of the solution to 3.5-4, then adding a sulfur ion solution, filtering and precipitating, and taking a filtrate to obtain the lanthanum chloride solution without non-rare earth impurities.

In the method, sulfate solution which does not influence the quality of the rare earth is added, so that the introduced non-rare earth impurities do not influence the quality of the rare earth.

In order to better highlight the technical effects of the present invention, the following examples of industrial production are listed:

example 1:

the traditional method for producing rare earth in rare earth hydrometallurgy comprises the following steps:

s1, dynamically oxidizing and roasting the rare earth bastnaesite concentrate with the rare earth grade of more than 65 percent and the PbO content of about 0.4 percent for about 2.5 hours in a rotary kiln at the temperature of 450-;

s2, performing primary acid leaching, alkali conversion, water washing and acid leaching on the rare earth bastnaesite concentrate subjected to oxidizing roasting, then performing quenching and tempering on the acid leaching solution, and concentrating the acid leaching solution to obtain a mixed rare earth chloride solution with the concentration of more than 280g/L and the PbO content of about 2.5 g/L;

s3, heating the mixed rare earth chloride to more than 80 ℃, adding sodium sulfide, wherein the addition amount of industrial sodium sulfide with the sodium sulfide content of more than 65 percent is more than 10 times of the theoretical amount of lead-removing sodium sulfide (according to the addition amount, lead in the mixed rare earth chloride can be removed to Pb0 of less than or equal to 0.01 percent), stirring for half an hour, and supplementing a soluble sulfate radical-containing solution into the lead-removing mixed rare earth chloride to remove barium radium until BaO of less than or equal to 0.1 percent; the pH value of the whole mixed rare earth chloride solution is adjusted to be between 3.5 and 4.5 by two times of operation;

s4, aging the mixed rare earth chloride after lead, barium and radium removal for 72 hours, preparing the acidity of the mixed rare earth chloride between 0.02 and 0.05mol/L, and performing organic mixed extraction separation (the organic is P507, and the saponification degree is 0.48) through calcium saponification to obtain single rare earth chloride, wherein PbO in the mixed rare earth chloride solution is enriched in the light rare earth lanthanum chloride solution;

and S5, precipitating, calcining and mixing the lanthanum chloride solution, and packaging to obtain a lanthanum oxide product. Wherein the PbO content in the lanthanum oxide is between 200 and 100ppm, and the lanthanum oxide with lower quality is obtained.

The traditional production process (original production process of the applicant) mainly removes PbO in an extraction tank after mixed rare earth chloride is fed, but in order to reduce the loss of valuable mixed rare earth, lead removal in a lead removal process is incomplete, so that the product quality of lanthanum oxide is influenced after PbO is enriched in a subsequent process, meanwhile, the loss of mixed rare earth chloride is about 3% after the process is adopted, especially the loss of praseodymium-neodymium oxide with higher added value in the mixed rare earth is about 2%, and meanwhile, equipment and raw and auxiliary materials of lost parts are also added for recovering valuable rare earth in lead-barium slag, so that the defect exposure is obvious.

Example 2:

a method for removing non-rare earth impurities in rare earth hydrometallurgy is characterized by comprising the following steps:

s1, dynamically oxidizing and roasting the rare earth bastnaesite concentrate with the rare earth grade of more than 65 percent and the PbO content of about 0.4 percent for about 2.5 hours in a rotary kiln at the temperature of 450-;

s2, performing primary acid leaching, alkali conversion, water washing and acid leaching on the rare earth bastnaesite concentrate subjected to oxidizing roasting, then performing quenching and tempering on the acid leaching solution, and concentrating the acid leaching solution to obtain a mixed rare earth chloride solution with the concentration of more than 280g/L and the PbO content of about 2.5 g/L;

s3, transferring the concentrated mixed rare earth chloride into an impurity removal tank, heating to a temperature above 80 ℃, adding a solution containing soluble sulfate radicals into the mixed rare earth chloride until BaO in the mixed rare earth chloride is less than or equal to 0.1%; then filtering and separating, pumping the filtrate into a storage tank for aging, packaging the filter residue and transferring to a dangerous waste storehouse for temporary storage;

s4, aging the mixed rare earth chloride after barium radium removal for 72 hours; then the acidity of the mixed rare earth chloride is prepared to be between 0.02 and 0.05mol/L, and single rare earth chloride is obtained after organic mixed extraction separation of calcium saponification (the organic phase is P507, and the saponification degree is 0.48), wherein PbO in the mixed rare earth chloride solution is enriched in a light rare earth lanthanum chloride solution, and the content of PbO in lanthanum chloride is about 3.5 g/L;

s5, transferring the lanthanum chloride solution to a lead removing tank, stirring and heating to above 80 ℃, adding sodium sulfide, wherein the content of sodium sulfide is above 65% of industrial-grade sodium sulfide, the addition amount is more than 10 times of the theoretical amount of lead-removing sodium sulfide (according to the addition amount, lead in the mixed rare earth chloride can be removed to Pb0 of less than or equal to 0.01%), stirring for half an hour, stopping stirring and filtering, pumping the filtrate into a precipitation tank, precipitating, spin-drying, calcining, mixing and packaging (finished products), so as to obtain a final lanthanum oxide product, and transferring the filter residue as a dangerous article to a dangerous waste storehouse for temporary storage.

In this example, the PbO in the mixed rare earth chloride is extracted and enriched into the lanthanum chloride solution, and then lead is removed from the PbO-enriched lanthanum chloride solution, so as to obtain a lanthanum oxide product after the subsequent precipitation process is completed, and the following advantages are achieved in the process: firstly, PbO is convenient to remove after being enriched; secondly, lead is removed from the mixed rare earth without chlorination, so that the loss of valuable rare earth is avoided, and the direct yield of praseodymium-neodymium can be improved by about 0.5% (namely the loss of praseodymium-neodymium oxide is below 1.5%); thirdly, because the added value of the lanthanum product is low, the lanthanum lost in lead removal does not need to be separately recovered, and the production equipment and the production cost are saved.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.