CN103484668A - Weathering crust illuviation-type rare-earth ore leaching agent and method for extracting rare earths by using same - Google Patents

Abstract

The invention provides a weathering crust leaching type rare earth ore leaching agent and a method for extracting rare earth. Specifically, it is a leaching agent solution for weathering crust leaching type rare earth ore, and its active ingredient is citrate; the citrate is any of ammonium citrate, sodium citrate, potassium citrate and magnesium citrate One, or a combination of sodium citrate, potassium citrate, and magnesium citrate. The method for extracting rare earth from weathering crust leaching type rare earth ore includes using citrate as the active component of ore leaching agent to obtain rare earth leaching mother liquor, removing impurities, and adding a precipitant to obtain rare earth enrichment. In the process of extraction of weathering crust elution-type rare earths, in addition to the exchange of cations, the present invention also has the cooperation of anions (citrate ions), and the synergy of the two effects can improve the recovery rate of rare earths and reduce the concentration and dosage of leaching agents.

Description

A weathering crust leaching type rare earth ore leaching agent and method for extracting rare earth

technical field

The invention belongs to the field of hydrometallurgy, and in particular relates to a weathering crust leaching type rare earth ore leaching agent and a method for extracting rare earth.

Background technique

The weathering crust elution-type rare earth ore is a special rare earth mineral with a high proportion of medium and heavy rare earth, and it is a strategic mineral for national development. The rare earth elements in the weathering crust leaching type rare earth ores are mainly adsorbed on the clay minerals in the form of hydrated or hydroxyl hydrated ions, and the rare earth grade is low, only 0.05-0.3%. The ore particle size is extremely fine, and more than 50% of the rare earths are stored in the -0.78mm particle size with a yield of 24-32%. Conventional physical beneficiation cannot enrich rare earths into corresponding rare earth concentrates, so chemical leaching can only be used technology.

When the weathering crust elution-type rare earth ore is washed with a salt electrolyte solution, the rare earth ions will be exchanged, similar to the ion exchange process. Whether it is strong alkali, strong acid, weak acid salt, strong acid weak alkali salt, high-valent salt or low-valent salt or organic acid, as well as alkali that can form complexes with rare earths, when the solution concentration is appropriate, it can effectively leach weathering crust. Ionic phase rare earths in deposit-type rare earth ores.

In order to improve the leaching efficiency, reduce resource consumption, reduce environmental pollution, and realize the efficient utilization of weathering crust leaching type rare earth resources, people have improved the leaching process from various aspects. Among them, the choice of leaching agent directly affects The level of leaching rate and the cost required for production are therefore very important and are currently the focus of research by many scientists. At present, the commonly used leaching agent is generally 1-4% ammonium sulfate, which has a high recovery rate of rare earths, but it is less produced in the south, and the demand for rare earth beneficiation is very large, so the supply is often in short supply. Therefore, it is necessary to find a leaching agent to replace ammonium sulfate.

Contents of the invention

The purpose of the present invention is to provide a new weathering crust leaching type rare earth ore leaching agent. In the process of leaching rare earth, this novel ore leaching agent not only has the exchange effect of cations but also the coordination leaching effect of anions, which is different from the current one. Compared with the commonly used ammonium sulfate leaching agent, it has the characteristics of lower leaching concentration and less dosage.

In order to achieve the above purpose, the following technical solutions are adopted:

A leaching agent solution for weathering crust elution type rare earth ore, the active ingredient of which is citrate.

According to the above scheme, the citrate is any one or any mixture of ammonium citrate, sodium citrate, potassium citrate and magnesium citrate.

According to the above scheme, the content of the citrate active ingredient is 0.5-2.0wt%.

According to the above scheme, the pH value of the ore leaching agent solution is between 3.0-8.0.

A method for extracting rare earths from weathering crust leaching type rare earth ores, comprising using citrate as an active ingredient of a leaching agent to obtain a rare earth leaching mother liquor, removing impurities, and adding a precipitating agent to obtain a rare earth enrichment.

According to the above scheme, the citrate is any one or any mixture of ammonium citrate, sodium citrate, potassium citrate and magnesium citrate.

According to the above scheme, the content of the citrate active ingredient is 0.5-2wt%.

According to the above scheme, it also includes adjusting the pH value of the ore leaching agent solution to 3.0-8.0.

According to the above scheme, hydrochloric acid was used to adjust the pH value.

According to the above scheme, the precipitation agent is oxalic acid or ammonium bicarbonate.

The leaching of weathering crust leaching type rare earth ore is essentially an ion exchange reaction, that is, the exchange process of rare earth ions in clay and cations in leaching agent. The chemical reaction equation when ammonium sulfate is used as a leaching agent is as follows:

[Al ₄ (Si ₄ O ₁₀ )(OH) ₈ ] _m ·nRE ³⁺ _(s) +3nNH ₄ ⁺ _(aq) =[Al ₄ (Si ₄ O ₁₀ )(OH) ₈ ] _m ·3nNH ₄ ⁺ _{( s)} +nRE _(aq)

The leaching exchange cations are exchanged with the rare earth ions on the mineral surface so that the cations are adsorbed to the mineral surface and the rare earth ions enter the solution. When the leaching agent used is citrate, the following chemical reactions take place:

[Al ₄ (Si ₄ O ₁₀ )(OH) ₈ ] _m nRE ³⁺ _(s) +nC ₆ H ₅ O ₇ ^3- +3nM _(aq) =[Al ₄ (Si ₄ O ₁₀ )(OH) ₈ ] _m 3nM _(s) +nC ₆ H ₅ O ₇ REM=NH ₄ ⁺ ,Na ⁺ ,K ⁺ ,Mg ²⁺ /2

From the above reactions, it can be known that during the leaching process, the cation of citric acid plays an ion exchange role with rare earth ions, and the anion (citrate ion) participates in the cooperation of rare earth ions, which promotes the leaching reaction to the right and promotes The leaching of rare earths improves the recovery rate of rare earths.

The beneficial effects of the present invention are:

1) The present invention uses one or a mixture of several kinds of citrates as the ore leaching agent. Compared with other ore leaching agents currently used, in the process of extracting the weathering crust leaching type rare earth, there is also a positive ion exchange effect. There is a synergistic effect of anion (citrate ion), and the synergy of the two effects can improve the recovery rate of rare earths and reduce the concentration and amount of leaching agent used.

2) The citrate used contains a small amount or no ammonium root, which can reduce the pollution of ammonia nitrogen wastewater. If ammonium-free salt is used, the pollution of ammonia nitrogen wastewater can be eliminated.

Detailed ways

The present invention will be further described below in conjunction with example, but does not limit the present invention.

Determination of the total content of rare earth in the ionic phase: Weigh 250.0 g of the dried weathering crust leaching type rare earth ore, use 2% ammonium sulfate solution as the leaching agent, and carry out column leaching to the weathering crust leaching type rare earth ore. Until almost no rare earth is leached out, the leachate is combined and collected, and the total ionic phase rare earth content is determined by EDTA volumetric method to be REO1.139mmol/250g rare earth ore.

Example 1

Take by weighing 250.0g of the dried weathering crust leaching type rare earth ore, and prepare an ammonium citrate ((NH ₄ ) ₃ C ₆ H ₅ O ₇ ) solution with a mass percentage of 0.5% as the ore leaching agent, according to the solid-to-liquid ratio (solid mass to leaching agent volume ratio) at a ratio of 1:2, adjust the flow rate at 0.4mL/min, perform column leaching on the weathering crust leaching type rare earth ore, and obtain the rare earth leaching mother liquor, and use the EDTA volumetric method to measure the rare earth content as REO1. 119mmol/250g rare earth ore, enriched by oxalic acid precipitation after removal of impurities, filtered, washed and burned at 900°C.

According to analysis and determination, the recovery rate of rare earth is 94.3% (the recovery rate is obtained by directly weighing the burning material and comparing the total ionic phase rare earth content), and the purity is 92.6% (using GB/T14635-2008).

Example 2

Weigh 250.0g of dried weathering crust elution-type rare earth ore, prepare a 1.5% by mass magnesium citrate (Mg ₂ (C ₆ H ₅ O ₇ ) ₃ ) solution as a leaching agent, add hydrochloric acid to adjust the pH to 5.0 According to the solid-liquid ratio of 1:2, the flow rate is adjusted to be controlled at 0.4mL/min, and the weathering crust leaching type rare earth ore is column leached to obtain the rare earth leaching mother liquor. The rare earth content is measured by EDTA volumetric method as REO0.0962mmol/250g Rare earth ores are enriched by oxalic acid precipitation after impurity removal, filtered and washed, and burned at 900°C.

After analysis and determination, the recovery rate of rare earth was 92.3%, and the purity was 92.3%.

Example 3

Weigh 250.0g of the dried weathered crust elution-type rare earth ore, and prepare a sodium citrate (Na ₃ C ₆ H ₅ O ₇ 2H ₂ O) solution with a mass percentage of 1.0% as the ore leaching agent. :2 ratio, adjust the flow rate to be controlled at 0.4mL/min, carry out column leaching to the weathering crust leaching type rare earth ore, obtain the rare earth leaching mother liquor and use the EDTA volumetric method to measure the rare earth content to be REO1.108mmol/250g rare earth ore, after removing impurities It is enriched by ammonium bicarbonate precipitation, filtered and washed, and burned at 900 °C.

After analysis and determination, the recovery rate of rare earth was 93.4%, and the purity was 92.1%.

Example 4

Weigh 250.0g of the dried weathering crust elution-type rare earth ore, prepare a 1.0% mass percent potassium citrate (K ₃ C ₆ H ₅ O ₇ ·H ₂ O) solution as the ore leaching agent, and use a solid-to-liquid ratio of 1 :2 ratio, adjust the flow rate to be controlled at 0.4mL/min, carry out column leaching to the weathering crust leaching type rare earth ore, obtain the rare earth leaching mother liquor and use the EDTA volumetric method to measure the rare earth content to be REO1.110mmol/250g rare earth ore, after removing impurities It was enriched by ammonium bicarbonate precipitation, filtered and washed, and burned at 900°C.

After analysis and determination, the recovery rate of rare earth was 93.6%, and the purity was 92.7%.

Example 5

Weigh 250.0g of the dried weathering crust leaching type rare earth ore, and prepare the following mixed citrate leaching agent (mass percentage): 0.5% sodium citrate, 0.5% potassium citrate, 0.5% magnesium citrate, and the rest is water , add hydrochloric acid to adjust the pH to 7.3, adjust the flow rate at 0.4mL/min according to the ratio of solid to liquid ratio of 1:2, carry out column leaching to the weathering crust leaching type rare earth ore, and obtain the rare earth leaching mother liquor and use the EDTA volumetric method to determine the rare earth The content is REO1.111mmol/250g rare earth ore. After removing impurities, it is enriched by oxalic acid precipitation, filtered and washed, and burned at 900 ° C.

After analysis and determination, the recovery rate of rare earth was 94.2%, and the purity was 92.2%.

Example 6

Weigh 250.0g of dried weathering crust elution-type rare earth ore, and use 1% ammonium sulfate and 1.28% ammonium citrate ((NH ₄ ) ₃ C ₆ H ₅ O ₇ ) solution is the ore leaching agent, and the ammonium ion content in the two ammonium salts used this time is the same (0.151mol/L NH ₄ ⁺ ), and column leaching is performed on the weathering crust leaching type rare earth ore to obtain the rare earth leaching mother liquor using EDTA capacity Rare earth content was determined by the method, enriched by oxalic acid precipitation after removal of impurities, filtered and washed, and burned at 900°C.

After analysis and determination, the rare earth content in the ammonium sulfate leaching solution is REO0.9646mmol/250g rare earth ore, the recovery rate of rare earth is 81.3%, and the purity is 92.3%; while the rare earth content in the ammonium citrate leaching solution is REO1.127mmol/250g rare earth ore, and the rare earth recovery rate is 81.3%. The yield was 95.0%, and the purity was 92.2%.

Example 7

Weigh 250.0g of dried weathering crust elution-type rare earth ore, and use 2% sodium citrate (Na ₃ C ₆ H ₅ O ₇ 2H ₂ O) and 1.192% Sodium chloride solution is the ore leaching agent. The sodium ion content in the two ammonium salts used this time is the same (0.204mol/LNa ⁺ ). Column leaching is performed on the weathering crust leaching type rare earth ore to obtain the rare earth leaching mother liquor using EDTA capacity Rare earth content was determined by the method, enriched by oxalic acid precipitation after removal of impurities, filtered and washed, and burned at 900°C.

After analysis and determination, the rare earth content in the sodium chloride leaching solution is 0.3319mmol/250g rare earth ore, the rare earth recovery rate is 28.1%, and the purity is 92.6%; while the rare earth content in the ammonium citrate leaching solution is 1.126mmol/250g rare earth ore, the rare earth recovery rate It is 94.9%, and the purity is 92.3%.

Example 8

Weigh 250.0g of dried weathering crust elution-type rare earth ore, and use 1.5% magnesium sulfate and 1.88% magnesium citrate solution (Mg ₂ (C ₆ H ₅ O ₇ ) ₃ ) is the leaching agent. The content of magnesium ions in the two leaching agents used this time is the same (0.125mol/L Mg ²⁺ ). Column leaching is performed on the weathering crust leaching type rare earth ore to obtain the rare earth leaching mother liquor using EDTA The content of rare earths was determined by volumetric method, enriched by oxalic acid precipitation after removal of impurities, filtered and washed, and burned at 900°C.

After analysis and determination, the rare earth content in the magnesium sulfate leaching solution is 0.7393mmol/250g. The recovery rate of rare earth ore is 62.3%, and the purity is 92.0%. The rare earth content in the ammonium citrate leaching solution is 1.112mmol/250g. The recovery rate of rare earth ore is 93.7%. , with a purity of 92.1%.

As can be seen from the results of examples 6, 7, and 8, when the cation concentration of the ore leaching agent was constant, the rare earth leaching rate of the citrate ore leaching agent was higher, because the coordination of citrate and rare earth ions promoted the carrying out of the leaching reaction , Improve the recovery rate of rare earth.

Claims (10)

1. One kind for weathered superficial leaching rare-earth ore soak the ore deposit agent solution, it is characterized in that activeconstituents is Citrate trianion.
2. As claimed in claim 1 for weathered superficial leaching rare-earth ore soak the ore deposit agent solution, it is characterized in that described Citrate trianion be ammonium citrate, Trisodium Citrate, Tripotassium Citrate and magnesium citrate any one or mix arbitrarily.
3. As claimed in claim 1 for weathered superficial leaching rare-earth ore soak the ore deposit agent solution, it is characterized in that described Citrate trianion active component content is 0.5-2.0wt%.
4. As claimed in claim 1 for weathered superficial leaching rare-earth ore soak the ore deposit agent solution, it is characterized in that the described ore deposit agent solution pH value of soaking between 3.0-8.0.
5. 5. the method for an Extraction of rare earth from weathered superficial leaching rare-earth ore, comprise and use Citrate trianion to obtain rare earth leaching mother liquor as soaking ore deposit agent activeconstituents, and removal of impurities, add precipitation agent to obtain rareearth enriching material.
6. 6. the method for Extraction of rare earth from weathered superficial leaching rare-earth ore as claimed in claim 5, it is characterized in that described Citrate trianion be ammonium citrate, Trisodium Citrate, Tripotassium Citrate and magnesium citrate any one or mix arbitrarily.
7. 7. the method for Extraction of rare earth from weathered superficial leaching rare-earth ore as claimed in claim 5, is characterized in that described Citrate trianion active component content is 0.5-2wt%.
8. 8. the method for Extraction of rare earth from weathered superficial leaching rare-earth ore as claimed in claim 5, characterized by further comprising and regulate the pH value to 3.0-8.0 to soaking the ore deposit agent solution.
9. 9. the method for Extraction of rare earth from weathered superficial leaching rare-earth ore as claimed in claim 5, adopt hydrochloric acid while it is characterized in that regulating the pH value.
10. 10. the method for Extraction of rare earth from weathered superficial leaching rare-earth ore as claimed in claim 5, is characterized in that described precipitation agent is oxalic acid or bicarbonate of ammonia.