CN105132720B - Method for recovering rare earth in ion adsorption type rare earth ore leaching solution through fractional precipitation - Google Patents

Abstract

The invention discloses a method for recovering rare earth in an ion adsorption type rare earth ore leaching solution through fractional precipitation. According to the method, firstly, a magnesium-containing alkaline compound is added to a purified ion adsorption type rare earth ore leaching solution for a precipitation reaction; and then a calcium-containing alkaline compound is further added for a precipitation reaction, and rare earth precipitation concentrates and precipitation mother liquor are obtained after solid-liquid separation. According to the method, raw materials adopted are cheap and easy to obtain, and the process is simple and easy to control, so that the production cost is lowered; the problem of ammonia and nitrogen pollution in the precipitation process of the ion adsorption type rare earth ore leaching solution is solved; meanwhile, the adding amount of the magnesium-containing/calcium-containing alkaline compound is controlled, so that a precipitant is dissolved fully as much as possible, and the purity of the rare earth precipitation concentrates is improved; in addition, sulfate ions and calcium ions in the leaching solution can form a small amount of calcium sulfate precipitate with the good crystallization property; crystals of rare earth hydrate can be induced, and the problem that the rare earth hydrate is not liable to form a crystal form precipitate can be also solved.

Description

A method for step-by-step precipitation recovery of rare earth in leach solution of ion-adsorption type rare earth ore

technical field

The invention relates to the field of rare earth hydrometallurgy, in particular to a method for step-by-step precipitation recovery of rare earth in leach solution of ion-adsorption type rare earth ore.

Background technique

Since the 1970s, the strategic position of rare earth elements has been increasing day by day, and has become an indispensable and important strategic resource in the process of high-tech development and traditional industry transformation. It is known as the "vitamin of modern industry" and "treasure house of new materials". Developed countries such as the United States and Japan have listed rare earths as "strategic elements in the 21st century" for strategic reserves and key research; my country has also listed rare earth materials as Priority themes and key support directions for basic raw materials in the manufacturing industry.

According to the differences in physical and chemical properties among rare earth elements, they are grouped into light, medium and heavy rare earth elements. Among them, europium, terbium, dysprosium and other medium and heavy rare earths have small reserves, large gaps, high value, and low substitutability. They are widely used in high-tech fields such as national defense, aerospace, and aerospace. They are ideal for preparing high-performance magnetic materials, luminescent materials, and laser crystals. , high-tech ceramics and other key materials. At present, medium and heavy rare earths mainly come from ion-adsorption rare earth ores in my country, and the distribution of medium and heavy rare earth elements such as terbium, dysprosium, europium, and yttrium is more than ten times or even dozens of times higher than that of light rare earth ores. Ion-adsorption rare earth ore is a new type of exogenous rare earth mineral, which was first discovered in Ganzhou, Jiangxi Province, my country in 1969, and is widely distributed in seven southern provinces including Jiangxi, Guangdong, Guangxi, Hunan, Fujian, Yunnan, and Zhejiang. This kind of minerals has a complete distribution of rare earths, low radioactivity, and is rich in medium and heavy rare earth elements. It is a valuable strategic mineral resource in my country.

In general, the full-phase rare earth grade in ion-adsorption rare earth ores is generally 0.05%-0.3%, of which 60%-95% of the rare earth elements exist in the ionic phase, and the rare earth elements in the ionic phase are in the form of rare earth hydrated ions or hydroxyl hydrated ions Adsorbed on clay minerals through electrostatic interaction, when these rare earth ions (ionic phase rare earths) adsorbed on clay minerals meet chemically active cations (such as Na ⁺ , Mg ²⁺ , Ca ²⁺ , NH ₄ ⁺ , etc.) , it can be desorbed by its exchange. Based on this characteristic, Chinese scientific and technological workers have successively developed leaching agents such as sodium chloride and ammonium sulfate, as well as leaching processes such as bucket leaching, pool leaching, heap leaching and in-situ leaching. At present, ion-adsorption type rare earth ores are usually leached with ammonium sulfate, and the obtained rare earth leachate is removed by ammonium bicarbonate, precipitated with ammonium bicarbonate or oxalic acid to recover rare earths, and then roasted to obtain a mixed rare earth oxide with a rare earth content of 90% based on REO. ore concentrate. The concentration of rare earth in ion ore rare earth leach solution is low, generally around 2g/L, and the impurity content is high. The existing ammonium bicarbonate/oxalic acid precipitation recovery rare earth recovery rate is low, the consumption of chemical reagents is large, the production cost is high, and ammonia nitrogen wastewater exists. Oxalic acid wastewater discharge and other issues.

In order to reduce production costs and reduce ammonia nitrogen pollution, CN101037219 uses magnesium oxide slurry as a precipitating agent to precipitate rare earths in rare earth solutions; CN101475202 uses calcium oxide or a mixture of calcium oxide and seed crystals as a precipitating agent to precipitate rare earths in rare earth solutions . Although the precipitant used in the above-mentioned patent can reduce the cost and eliminate ammonia nitrogen pollution at the same time, when the above-mentioned method is used to precipitate ion-adsorption type rare earth ore leachate, since magnesium oxide is a very slightly soluble substance, the precipitation reaction time is long, and in order to ensure For the precipitation rate of rare earth in the solution, the precipitation agent needs to be excessive. At this time, the excessive unreacted precipitation agent will enter the rare earth precipitation enrichment, which greatly reduces the purity of the rare earth concentrate product. Calcium oxide is a slightly soluble substance, and the precipitation reaction is fast. However, since the ionic ore leachate contains a large amount of sulfate radicals, calcium oxide is used as a precipitant alone, which will produce a large amount of calcium sulfate in the process of precipitating the ion ore leachate. Precipitation, Also reduce the purity of rare earth concentrate products.

In order to solve the above-mentioned problem of the purity of rare earth concentrate products, CN103436720 proposes to use a two-step precipitation method of magnesium hydroxide/calcium hydroxide and sodium hydroxide to precipitate a low-concentration rare earth leachate. However, expensive sodium hydroxide is used in this process, which greatly increases the production cost. At the same time, it is difficult to obtain rare earth hydroxide with good crystallization properties, which makes the rare earth precipitate enrichment have a high water content, reduces production capacity, and increases production energy consumption. CN102190325 (a method for recovering rare earths from ionic rare earth ore) discloses that magnesium bicarbonate or/and calcium bicarbonate aqueous solution is used as a precipitating agent to precipitate rare earths in the leaching solution to obtain rare earth carbonates, which reduces production costs, but the prepared pure Magnesium bicarbonate or/and calcium bicarbonate aqueous solution equipment is more complicated, and investment is larger. CN104152693 discloses the use of a magnesium-containing precipitant to precipitate a low-concentration rare earth leaching solution, and then passes carbon dioxide gas into the magnesium-containing rare earth precipitate. The purpose of introducing carbon dioxide is to speed up the reaction and remove the magnesium in the precipitated product, so that the precipitate in the precipitate The magnesium is converted into easily soluble magnesium bicarbonate into the solution, and the rare earth is converted into a rare earth carbonate precipitate. However, the results of the paper "Effect of impurity ions on the preparation of novel saponifier forrare earth extraction" (Jounal of rare earth, 2013, Volume 34, Issue 1) show that most magnesium compounds cannot be carbonized in the presence of rare earths Magnesium bicarbonate solution, but generate magnesium carbonate precipitation, can't substantially improve the purity of rare earth concentrate product.

Therefore, the current method for recovering rare earths from the leach solution of ion-adsorption rare earth ores still cannot not only reduce production costs, reduce ammonia nitrogen pollution, but also ensure the purity of rare earths in the product.

Contents of the invention

The main purpose of the present invention is to provide a step-by-step precipitation recovery method for rare earth in leach solution of ion-adsorption type rare earth ore, so as to reduce production cost, reduce ammonia nitrogen pollution, ensure the purity of rare earth in the product, and facilitate industrialization.

In order to achieve the above object, a method for recovering rare earths in ion-adsorption type rare earth ore leachate by stepwise precipitation is provided, comprising the following steps: firstly, adding magnesium-containing basic compound to the ion-adsorption type rare earth ore leachate after impurity removal treatment for precipitation reaction, and then add a calcium-containing basic compound to carry out a precipitation reaction, and obtain a rare earth precipitation enrichment and a precipitation mother liquor after solid-liquid separation; wherein, in terms of magnesium oxide, the addition amount of a magnesium-containing basic compound is the rare earth ion in the leachate X wt% of the theoretical amount required for complete precipitation; calculated as calcium oxide, the amount of the calcium-containing basic compound is Y wt% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, 10%≤X%≤80% , 25%≤Y%≤120%, 105%≤X%+Y%≤130%.

Further, the concentration of sulfate ions in the leach solution of the ion-adsorption type rare earth ore after impurity removal treatment is 0.2 g/L-20 g/L.

Further, in terms of REO, the concentration of rare earth in the ion-adsorption type rare earth ore leachate after impurity removal treatment is 0.2-30 g/L.

Further, the magnesium-containing basic compound is at least one of magnesium oxide, magnesium hydroxide, and a roasted product of magnesium-containing minerals.

Further, the calcium-containing basic compound is at least one of calcium oxide, calcium hydroxide, and calcined products of calcium-containing minerals.

Further, the magnesium-containing mineral is at least one of serpentine, magnesite and brucite.

Further, the calcium-containing mineral is at least one of limestone, marble, and calcite.

Further, in terms of magnesium oxide, the addition of the magnesium-containing basic compound is X wt% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate; in terms of calcium oxide, the addition of the calcium-containing basic compound is the Y wt% of the theoretical amount required for the complete precipitation of rare earth ions in the leach solution, 30%≤X%≤70%, 35%≤Y%≤100%, 105%≤X%+Y%≤130%.

Further, in the step of adding a magnesium-containing basic compound for precipitation reaction, the reaction temperature is 5°C-90°C; in the step of adding a calcium-containing basic compound for precipitation reaction, the reaction temperature is 5°C-90°C.

Further, based on REO, the rare earth content in the precipitation mother liquor obtained after precipitation is less than 0.1 g/L.

In the present invention, the magnesium-containing basic compound is firstly added as a precipitating agent into the ion-adsorption type rare earth ore leachate after impurity removal treatment. At this time, the higher rare earth concentration is beneficial to the dissolution of the slightly soluble magnesium basic compound, making it After fully reacting, the calcium-containing basic compound is added as a precipitating agent into the leaching solution to precipitate the remaining rare earth, and solid-liquid separation is carried out to obtain the rare earth precipitation enrichment. The raw materials used in the method are cheap and easy to obtain, and the process is simple and easy to control, which reduces the production cost and eliminates the problem of ammonia nitrogen pollution in the precipitation process of the leach solution of the ion-adsorbed rare earth ore. The precipitant should be dissolved as completely as possible to improve the purity of the rare earth precipitate enrichment, and the sulfate ions and calcium ions in the leaching solution can form a small amount of calcium sulfate precipitate with good crystallization properties, which can induce the crystallization of rare earth hydroxide and solve the problem of hydroxide Rare earth is not easy to form the problem of crystalline precipitation.

detailed description

It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below in conjunction with embodiments.

It can be seen from the background technology that the existing methods for recovering rare earths from the leach solution of ion-adsorption rare earth ores cannot not only reduce production costs, reduce ammonia nitrogen pollution, but also ensure the purity of rare earths in the product.

The invention provides a step-by-step precipitation recovery method for rare earth in ion-adsorption type rare earth ore leachate, which comprises the following steps: firstly, adding magnesium-containing alkaline compound to the ion-adsorption type rare earth ore leachate after impurity removal treatment for precipitation reaction, Then add calcium-containing basic compound to carry out precipitation reaction, obtain rare earth precipitation enrichment and precipitation mother liquor after solid-liquid separation; X wt% of the required theoretical amount; in terms of calcium oxide, the amount of the calcium-containing basic compound is Y wt% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, 10%≤X%≤80%, 25 %≤Y%≤120%, 105%≤X%+Y%≤130%.

The present invention is aimed at stepwise precipitation and recovery of rare earths from ion-adsorption type rare earth ore leachate after impurity removal treatment. The concentration of sulfate ions in the leachate is 0.2g/L~20g/L, and the concentration of rare earths is 0.2~30g/L. L (calculated in REO). The leaching solution is obtained from the existing industrial extraction process of ion-adsorption rare earth ores. The ion-adsorption rare earth ores are leached through ammonium sulfate/magnesium sulfate and other leaching agent solutions, and then ammonium bicarbonate/sodium hydroxide/ After removing impurities such as sodium bicarbonate/magnesium oxide, the ion-adsorption type rare earth ore leachate after impurity removal treatment is directly obtained. In addition, since sulfate radicals exist in the ion-adsorption type rare earth mineral soil itself, non-sulfate leaching agents (such as ammonium nitrate, ammonium chloride, sodium chloride, calcium chloride, etc.) can also be used to obtain the present invention. The ion-adsorption type rare earth ore leachate.

First add magnesium-containing basic compound for precipitation reaction, then add calcium-containing basic compound for precipitation reaction, and control the amount of magnesium-containing/calcium-containing basic compound 10 %≤X %≤80%, 25%≤Y%≤ 120%, 105%≤X%+Y%≤130%, after solid-liquid separation, rare earth precipitation enrichment and precipitation mother liquor are obtained. Since the basic compound containing magnesium/calcium has the advantage of being simple and easy to obtain, the cost of rare earth used in the precipitation recovery leachate is low, and there is no ammonia nitrogen pollution in the precipitation process, and the calcium and magnesium ions produced by the precipitation can be used in the leaching process. However, magnesium-containing basic compounds have low solubility in water and weak alkalinity, and their precipitation alone may affect the purity of the final rare earth product. Calcium-containing alkaline compounds have higher solubility in water and stronger alkalinity, which is beneficial to reduce the precipitation reaction time and control the purity of the final precipitated product, but there is also the problem that a large amount of calcium sulfate precipitates are easily formed and the purity of the product is reduced when it is used alone for precipitation. Therefore, in the present invention, a certain amount of magnesium-containing basic compound is first added to the leaching solution to accelerate the dissolution reaction under the condition of high rare earth concentration and reduce the residue of insoluble matter. Then add the calcium-containing basic compound to precipitate the remaining rare earth in the leachate. Because of its high solubility, it is difficult to have insoluble residues. At the same time, the addition of calcium-containing basic compounds provides calcium ions, which is beneficial to the formation of a small amount of calcium sulfate in the system and is beneficial to inducing the crystallization of rare earth hydroxides.

Preferably, the added amount of the magnesium/calcium-containing basic compound is 30%≤X%≤70%, 35%≤Y%≤100%, and 105%≤X%+Y%≤130%. In the above preferred range, it is to better ensure that the precipitation process of magnesium-containing basic compounds is carried out at a higher rare earth concentration, which is conducive to improving the precipitation rate, and at the same time helps to control the amount of insolubles in the final precipitation product, and improve the rare earth product. purity. At the same time, taking into account the Ksp of calcium sulfate, so that the remaining rare earth ions can be completely precipitated during the precipitation of calcium-containing basic compounds, and at the same time react with sulfate ions in the raw material to form a small amount of calcium sulfate precipitation, which is beneficial to induce the crystal form of rare earth hydroxides Precipitate without generating too much calcium sulfate so as to affect the purity of the precipitated product.

The magnesium-containing basic compound used is at least one of magnesium oxide, magnesium hydroxide, and roasted products of magnesium-containing minerals. The magnesium-containing mineral is at least one of serpentine, magnesite and brucite. The calcium-containing basic compound used is at least one of calcium oxide, calcium hydroxide, and calcined products of calcium-containing minerals. The calcium-containing mineral is at least one of limestone, marble and calcite. Compared with traditional precipitating agents such as sodium hydroxide, sodium carbonate, oxalic acid, etc., the above-mentioned magnesium/calcium-containing alkaline compounds are cheap and easy to obtain, and the process is simple and easy to control, which is conducive to reducing production costs.

In the step of adding the basic compound containing magnesium to carry out the precipitation reaction, the reaction temperature is 5°C-90°C. The reaction can be carried out at normal temperature, and can also be properly heated, which is conducive to accelerating the precipitation reaction speed. The reaction time can be adjusted according to the actual situation.

In the step of adding calcium-containing basic compound to carry out precipitation reaction, the reaction temperature is 5°C-90°C. Similarly, the reaction can be carried out at normal temperature, and can also be properly heated, which is conducive to accelerating the precipitation reaction speed. The reaction time can be adjusted according to the actual situation.

The invention adopts step-by-step precipitation to recover the rare earth in the ion-adsorption type rare earth ore, and finally obtains the rare earth precipitation concentrate and precipitation mother liquor. Rare earth precipitate concentrates can be calcined to obtain rare earth concentrate products; the content of rare earth in the precipitated mother liquor obtained after precipitation is less than 0.1g/L (calculated by REO), so as to ensure a high recovery rate of rare earth.

The method for step-by-step precipitation recovery of rare earths in ion-adsorption type rare earth ore leachate provided by the present invention will be further described below in conjunction with examples.

Comparative Example 1

Take 10L of ion-adsorption type rare earth ore leaching solution after impurity removal treatment, its rare earth concentration is 1.5g/L (REO calculation), sulfate radical concentration is 4.0g/L. According to 110% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, add 9.12g of calcium oxide to the leachate, react at 40°C for 3 hours, and perform solid-liquid separation after the reaction to obtain the rare earth precipitation enrichment and precipitation mother liquor , the rare earth concentration in the precipitation mother liquor is 0.03g/L (REO calculation), and the rare earth precipitation enrichment is calcined at 800°C to obtain the rare earth concentrate product, and its rare earth purity is 86.5wt% (REO calculation).

Comparative Example 2

Take 10L of ion-adsorption type rare earth ore leaching solution after impurity removal treatment, its rare earth concentration is 1.5g/L (REO calculation), sulfate radical concentration is 4.0g/L. According to 110% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, add 6.51g of magnesium oxide to the leachate, react at 40°C for 3 hours, and perform solid-liquid separation after the reaction to obtain the rare earth precipitation enrichment and precipitation mother liquor , the solid-liquid separation time is 110min. The rare earth concentration in the precipitation mother liquor is 0.05g/L (REO calculation), and the rare earth precipitation enrichment is calcined at 800°C to obtain a rare earth concentrate product with a rare earth purity of 79.7wt% (REO calculation).

Example 1

Take 10L of ion-adsorption type rare earth ore leaching solution after impurity removal treatment, its rare earth concentration is 1.5g/L (REO calculation), sulfate radical concentration is 4.0g/L. First, according to 60% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, add 3.55g of magnesium oxide to the leachate, react at 40°C for 2 hours, and then use the theoretical amount required for the complete precipitation of rare earth ions in the leachate 50%, add 4.14g of calcium oxide to the leaching solution, and react at 40°C for 1 hour. After the reaction, solid-liquid separation is carried out to obtain the rare earth precipitation enrichment and precipitation mother liquor, and the solid-liquid separation takes 20 minutes. The rare earth concentration in the precipitation mother liquor is 0.02g/L (REO calculation), and the rare earth precipitation concentrate is calcined at 800°C to obtain a rare earth concentrate product with a rare earth purity of 92.5wt% (REO calculation).

Example 2

Take 100L of ion-adsorption type rare earth ore leaching solution after impurity removal treatment, the rare earth concentration is 0.2g/L (REO calculation), and the sulfate concentration is 2.0g/L. First, according to 30% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, add 2.37g of magnesium hydroxide (calculated as magnesium oxide) to the leachate, react at 60°C for 2 hours, and then press the amount of rare earth ions in the leachate 85% of the theoretical amount required for complete precipitation, add 9.39g of calcium hydroxide (calculated as calcium oxide) to the leaching solution, and react at 60°C for 1 hour. After the reaction, solid-liquid separation is carried out to obtain rare earth precipitate enrichment and precipitation mother liquor. The concentration of rare earth in the precipitation mother liquor is 0.005g/L (REO calculation), and the rare earth precipitation enrichment is calcined at 800°C to obtain rare earth concentrate products. It is 91.7wt% (REO calculation).

Example 3

Take 100L of ion-adsorption type rare earth ore leaching solution after impurity removal treatment, the rare earth concentration is 0.2g/L (REO calculation), and the sulfate concentration is 2.0g/L. First, according to 13% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, add 1.03g of magnesium hydroxide (calculated as magnesium oxide) to the leachate, react at 60°C for 2 hours, and then press the rare earth ion in the leachate 102% of the theoretical amount required for complete precipitation, add 11.27g of calcium hydroxide (calculated as calcium oxide) to the leaching solution, and react at 60°C for 1 hour. After the reaction, solid-liquid separation is carried out to obtain rare earth precipitate enrichment and precipitation mother liquor. The concentration of rare earth in the precipitation mother liquor is 0.004g/L (REO calculation), and the rare earth precipitation enrichment is calcined at 800°C to obtain rare earth concentrate products. It is 90.3wt% (REO calculation).

Example 4

Take 10L of ion-adsorption type rare earth ore leach solution after impurity removal treatment, its rare earth concentration is 10g/L (REO calculation), and the sulfate concentration is 0.2g/L. First, according to 10% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, add 3.95g of magnesium oxide to the leachate, react at 80°C for 1 hour, and then use the theoretical amount required for the complete precipitation of rare earth ions in the leachate 120%, add 66.32g of calcium hydroxide (calculated as calcium oxide) to the leaching solution, and react at 5°C for 2 hours. After the reaction, solid-liquid separation is carried out to obtain rare earth precipitate enrichment and precipitation mother liquor. The concentration of rare earth in the precipitation mother liquor is 0.02g/L (REO calculation), and the rare earth precipitation enrichment is calcined at 800°C to obtain rare earth concentrate products. It is 90.7wt% (REO calculation).

Example 5

Take 10L of ion-adsorption type rare earth ore leach solution after impurity removal treatment, its rare earth concentration is 30g/L (REO), and the sulfate concentration is 20g/L. First, according to 80% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, add 94.74g of magnesium hydroxide (calculated as magnesium oxide) to the leachate, react at 90°C for 2 hours, and then press the rare earth ion in the leachate 25% of the theoretical amount required for complete precipitation, add 41.45g of calcium hydroxide (calculated as calcium oxide) to the leaching solution, and react at 15°C for 2 hours. After the reaction, solid-liquid separation is carried out to obtain rare earth precipitate enrichment and precipitation mother liquor. The concentration of rare earth in the precipitation mother liquor is 0.1g/L (REO calculation), and the rare earth precipitation enrichment is calcined at 800°C to obtain rare earth concentrate products. It is 89.1wt% (REO calculation).

Example 6

Take 10L of ion-adsorption type rare earth ore leach solution after impurity removal treatment, the concentration of rare earth is 20g/L (REO), and the concentration of sulfate is 8g/L. First, according to 70% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, add 55.26g of magnesite roasting product (calculated as magnesium oxide) containing 98.5wt% magnesium oxide to the leachate, and react at 25°C for 3 hours, and then according to 35% of the theoretical amount required for complete precipitation of rare earth ions in the leachate, add 38.68g of calcium hydroxide (calculated as calcium oxide) to the leachate, and react at 90°C for 0.5 hours. After the reaction, solid-liquid separation is carried out to obtain rare earth precipitate enrichment and precipitation mother liquor. The concentration of rare earth in the precipitation mother liquor is 0.1g/L (REO calculation), and the rare earth precipitation enrichment is calcined at 800°C to obtain rare earth concentrate products. It is 90.2wt% (REO calculation).

Example 7

Take 10L of ion-adsorption type rare earth ore leach solution after impurity removal treatment, the concentration of rare earth is 5g/L (REO), and the concentration of sulfate is 1g/L. First, according to 20% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, add 3.95g of magnesium oxide to the leachate, react at 5°C for 2 hours, and then press the theoretical amount required for the complete precipitation of rare earth ions in the leachate 100%, add 27.63g calcite roasted product (calculated as calcium oxide) containing 98wt% calcium oxide to the leaching solution, and react at 25°C for 3 hours. After the reaction, solid-liquid separation is carried out to obtain rare earth precipitate enrichment and precipitation mother liquor. The rare earth concentration in the precipitation mother liquor is 0.05g/L (REO calculation), and the rare earth precipitation enrichment is calcined at 800°C to obtain rare earth concentrate products. It is 89.4wt% (REO calculation).

Example 8

Take 10L of ion-adsorption type rare earth ore leach solution after impurity removal treatment, its rare earth concentration is 3g/L (REO calculation), sulfate radical concentration is 15g/L. First, add 8.88g of a mixture of magnesium oxide and magnesium hydroxide (the mass ratio of magnesium oxide and magnesium hydroxide is 1:1) to the leach solution according to 75% of the theoretical amount required for the complete precipitation of rare earth ions in the leach solution (in the form of oxidation magnesium), reacted at 25°C for 3 hours, and then added 5.80 g of a mixture of calcium oxide and calcium hydroxide (calcium oxide and hydroxide The mass ratio of calcium is 1:1) (calculated as calcium oxide), react at 25°C for 1 hour. After the reaction, solid-liquid separation is carried out to obtain rare earth precipitate enrichment and precipitation mother liquor. The concentration of rare earth in the precipitation mother liquor is 0.04g/L (REO calculation), and the rare earth precipitation enrichment is calcined at 800°C to obtain rare earth concentrate products. It is 89.7wt% (REO calculation).

Example 9

An ion-type rare earth mine in Longnan, the thickness of the rare earth layer is 6 meters, and the average grade of rare earth is 0.13%. The rare earth reserves of the ore body are 54 tons. The in-situ leaching process is adopted to complete the processes of injecting liquid wells on the surface of the ore body, collecting liquid holes, and laying pipelines. Prepare 8000m ³ of 2% ammonium sulfate leaching agent. Use the liquid injection pump to inject 350m ³ of the leaching agent every day. The rare earth concentration in the leachate is less than 0.2g/L at the beginning, and all pumps are pumped back to continue leaching. Reduce the concentration of ammonium sulfate in the leaching agent, and when the rare earth content in the leachate to be collected is close to the reserve, add clean water to rinse the liquid. The collected leachate is treated with 10g/L ammonium bicarbonate solution to adjust the pH to about 5 for impurity removal.

Take 10L of ion-adsorption type rare earth ore leach solution after magnesium oxide removal treatment, the rare earth concentration is 1.0g/L (REO), and the sulfate concentration is 3.6g/L. First, according to 65% of the theoretical amount required for the complete precipitation of rare earth ions in the leaching solution, add 2.57g of a mixture of magnesium hydroxide (calculated as magnesium oxide) to the leaching solution, react at 25°C for 3 hours, and then press the leaching solution 35% of the theoretical amount required for complete precipitation of rare earth ions, 2.49g of calcium oxide was added to the leaching solution, and the reaction was carried out at 25°C for 1.5 hours. After the reaction, solid-liquid separation is carried out to obtain rare earth precipitate enrichment and precipitation mother liquor. The concentration of rare earth in the precipitation mother liquor is 0.02g/L (REO calculation), and the rare earth precipitation enrichment is calcined at 800°C to obtain rare earth concentrate products. It is 92.2wt% (REO calculation).

Claims (8)

1. A method for step-by-step precipitation recovery of rare earth in ion-adsorption type rare earth ore leachate, characterized in that, firstly, adding magnesium-containing alkaline compound in the ion-adsorption type rare earth ore leachate after impurity removal treatment and carrying out precipitation reaction, and then Add calcium-containing basic compound to carry out precipitation reaction, and obtain rare earth precipitation enrichment and precipitation mother liquor after solid-liquid separation; Wherein, the concentration of sulfate ion in the leaching solution is 0.2g/L～20g/L; In terms of magnesium oxide, the addition amount of the magnesium-containing basic compound is X wt% of the theoretical amount required for the complete precipitation of rare earth ions in the leaching solution; In terms of calcium oxide, the amount of the calcium-containing basic compound is Y wt% of the theoretical amount required for the complete precipitation of rare earth ions in the leachate, 30%≤X%≤70%, 35%≤Y%≤100%, 105 %≤X%+Y%≤130%. 2. The method according to claim 1, characterized in that, in terms of REO, the concentration of rare earth in the leachate is 0.2 ~ 30g/L. 3. The method according to claim 1, characterized in that, the magnesium-containing basic compound is at least one of magnesium oxide, magnesium hydroxide, and a roasted product of magnesium-containing minerals. 4. The method according to claim 1, characterized in that the calcium-containing basic compound is at least one of calcium oxide, calcium hydroxide, and calcined products of calcium-containing minerals. 5. The method according to claim 3, wherein the magnesium-containing mineral is at least one of serpentine, magnesite, and brucite. 6. The method according to claim 4, wherein the calcium-containing mineral is at least one of limestone, marble, and calcite. 7. The method according to claim 1, characterized in that, in the step of adding a magnesium-containing basic compound to carry out a precipitation reaction, the reaction temperature is 5° C. to 90° C.; the adding a calcium-containing basic compound to carry out a precipitation reaction In the step, the reaction temperature is 5°C to 90°C. 8. The method according to claim 1, characterized in that, based on REO, the rare earth content in the precipitation mother liquor is below 0.1 g/L.