CN114574702A - Novel method for recovering rare earth from neodymium iron boron reclaimed materials - Google Patents

Abstract

The invention belongs to the technical field of rare earth recovery and extraction, and particularly relates to a novel method for recovering rare earth from a neodymium iron boron recovered material. The method comprises the steps of preparing neodymium iron boron waste into neodymium iron boron waste powder, sieving the neodymium iron boron waste powder, mixing the neodymium iron boron waste powder into slurry, adding quantitative hydrochloric acid to dissolve neodymium iron boron reclaimed materials, adding a conversion agent to enable rare earth in the neodymium iron boron reclaimed materials to be dissolved into feed liquid while iron and boron are both remained in slag, heating to 85-90 ℃ after reaction is completed, adjusting the pH to 3.0-3.5 by using a pH regulator to remove impurity ions, continuing to react for 10-15 minutes, adding a flocculating agent to flocculate and clarify, filtering and washing the slag to obtain feed liquid and material slag containing rare earth, and extracting and separating the feed liquid to obtain single rare earth oxide. Hydrochloric acid and a conversion agent are used as leaching agents to selectively leach rare earth, so that the rare earth is dissolved in feed liquid, iron and boron are remained in slag and are not dissolved, the yield of the rare earth is over 98.6 percent, and the efficient recovery of valuable rare earth in neodymium iron boron waste is realized.

Description

A new method for recovering rare earth from NdFeB recycled material

technical field

The invention belongs to the technical field of rare earth recovery and extraction, and in particular relates to a new method for recovering rare earths from NdFeB recycled materials.

Background technique

NdFeB permanent magnets have excellent performance, and high-performance NdFeB permanent magnet materials are widely used in high-tech fields such as computers, motors, and MRI machines. The production process of NdFeB permanent magnet materials is relatively mature, but there are still certain problems. During the production process of NdFeB magnets, due to equipment and process reasons, wastes that account for about 25% of the raw materials will be generated, and the mass fraction of rare earth components will be generated. About 35% of the rare earth resources are non-renewable. The use of economical and effective processes to recycle valuable rare earths in NdFeB waste can create certain economic value, save resources and reduce environmental pollution.

The generation of NdFeB waste mainly comes from the loss during machining and unqualified products during surface treatment. Due to different production processes, the shape of NdFeB waste is also very different, including powder, granular, block, and mud. The structure and texture of NdFeB waste are also different, which also brings certain difficulties to the treatment of NdFeB waste.

Due to the great recycling value of NdFeB waste, the majority of scientific researchers have done a lot of related research on the recovery of valuable rare earths from NdFeB waste. Acid leaching NdFeB wastes with hydrochloric acid, sulfuric acid, etc., and then further recovering rare earths from the leaching solution. This method is simple to operate and has a high rare earth leaching rate, but will produce a large amount of acidic wastewater, pollute the environment, and have high treatment costs. The other is the hydrochloric acid leaching method. This process requires high-temperature oxidative roasting of the NdFeB waste first. After the high-temperature oxidative roasting, the iron in the NdFeB becomes ferric oxide, which is less soluble in hydrochloric acid, so the hydrochloric acid can be reused. For selective leaching of valuable rare earths, this process requires high temperature and long-term oxidative roasting, which has high requirements on equipment materials, and has a long process, which causes great pollution to the environment during the oxidative roasting process.

SUMMARY OF THE INVENTION

Aiming at the problems of different forms of NdFeB waste in the prior art, it is difficult to handle, the existing recycling method pollutes the environment, the cost is high, the requirements for equipment materials are high, and the process is long. A new method for recovering rare earths from boron recyclate.

The technical scheme adopted in the present invention is as follows:

A new method for recovering rare earth from NdFeB recycled material, comprising the following steps:

Step 1: Mixing: Mixing various forms of NdFeB wastes to obtain NdFeB wastes that are dry and wet evenly and are convenient for abrasive sample preparation;

Step 2: Grinding and preparing samples: adding the NdFeB waste obtained in Step 1 to the sample preparation machine for grinding to obtain NdFeB waste powder;

Step 3: sieving and sizing: sieve the NdFeB waste powder obtained in step 2 by sizing to obtain oversize and undersize, detect the content of rare earth and iron in the undersize, and sieve the undersize. Make a slurry with water;

Step 4: leaching: slowly add hydrochloric acid to the slurry obtained in step 3, and then slowly add the conversion agent after the addition of the hydrochloric acid to leaching the rare earth;

Step 5: flocculation and clarification: the feed liquid obtained in step 4 is heated to 85-90 ℃, then add pH adjuster, adjust the pH value of feed liquid to 3.0-3.5, wait for 10-15min, add flocculant to the feed liquid to flocculate clarify;

Step 6: filter and wash the residue: filter the feed solution obtained in step 5 to obtain filter residue and rare earth chloride feed solution, and rinse the filter residue until the rare earth concentration in the washing water is less than 0.5g/L, and then stop leaching to obtain feed residue and washing water with low concentration of rare earth chloride;

Step 7: Detection: drying and weighing the slag and detecting the grade of rare earth, and calculating the recovery rate of rare earth according to the detection result.

After adopting the technical scheme, the NdFeB waste is first mixed and then sampled with a sample preparation machine to obtain NdFeB waste powder, the NdFeB waste powder is sieved and then adjusted into slurry with water, and then quantitative hydrochloric acid is added to carry out Dissolve the NdFeB recycled material, and then add the conversion agent so that the rare earth in the NdFeB recycled material is dissolved into the feed liquid and both iron and boron remain in the slag. The temperature is strictly controlled during this reaction process. After the reaction is completed, the temperature is raised to 85-90 °C, the pH is adjusted to 3.0-3.5 with a pH regulator to remove impurity ions, the reaction is continued for 10-15 minutes, and then a flocculant is added to flocculate and clarify, and the rare earth chloride feed solution is obtained after filtering and washing the residue. and filter residue, the rare earth chloride feed liquid is extracted and separated to obtain single rare earth oxide, and the filter residue is washed with water to obtain washing water with low concentration of rare earth chloride. . The NdFeB waste is selectively leached out of rare earths through hydrochloric acid and conversion agent as leaching agents, so that rare earths are dissolved into the feed liquid, while iron and boron remain in the slag and are not dissolved. Efficient recovery of valuable rare earths from NdFeB waste.

Preferably, the concentration of the hydrochloric acid in step 4 is 30%, and the mass ratio of the undersize to the added hydrochloric acid is 1:(0.69-0.86).

After adopting this technical scheme, the amount of hydrochloric acid required to dissolve the rare earth is calculated according to the detection result of the rare earth content in the NdFeB waste powder. The amount of hydrochloric acid actually added was 1.2 times the calculated amount.

The conversion agent described in the preferred step 4 is hydrogen peroxide, the concentration of the hydrogen peroxide is 28-30%, and the mass ratio of the undersize to the added hydrogen peroxide is 1:(0.78-0.85).

After adopting this technical scheme, according to the detection result of the iron content in step 3, calculate the amount of hydrogen peroxide required to oxidize the divalent iron ions in the solution after adding hydrochloric acid to trivalent iron ions, but because the pH of the entire reaction system is higher than The hydrolysis pH of ferric ions, so the precipitation of ferric hydroxide is formed while oxidizing ferrous iron and the corresponding hydrogen ions are released, and the hydrogen ions continue to dissolve the recycled material. The utilization rate of hydrogen peroxide in the whole process is only 90%, so the actual addition The amount of hydrogen peroxide is 1.12 times the calculated amount.

Preferably, the temperature of the leaching in step 4 is 50-55° C., and the time is 1.5-3.5 h.

After adopting this technical scheme, adding hydrochloric acid and transforming agent is an exothermic reaction. In order to improve the utilization rate of transforming agent, it is carried out under this temperature condition, and the leaching time is 1.5-3.5 to ensure the leaching rate of rare earth.

Preferably, the pH adjusting agent in step 5 is ammonium bicarbonate.

After adopting this technical scheme, the ferric ions in the feed liquid are removed by adjusting the pH value of ammonium bicarbonate.

Preferably, the flocculant in step 5 is polyacrylamide.

After adopting this technical scheme, the feed liquid is clarified and flocculated by polyacrylamide to prepare for the subsequent filtration step.

Preferably, in step 3, the obtained oversize is added to the sample making machine to continue grinding.

After adopting the technical solution, the NdFeB waste is ground to a sufficient degree of fineness and then the subsequent steps are carried out to improve the recovery rate of rare earth.

Preferably, the mass ratio of the undersize in step 3 to the added water is 1:(1.75-2).

After adopting the technical scheme, the NdFeB waste powder and water are adjusted into a slurry to facilitate leaching.

Preferably, the sample sieve described in step 3 is a 200-mesh sample sieve.

After adopting this technical scheme, it is ensured that the material under the sieve is sufficiently fine, and the leaching rate of rare earth is improved.

Preferably, the washing water with low concentration of rare earth chloride obtained in step 6 is used as sizing water in step 3.

After adopting the technical scheme, the rare earth chloride in the washing water is recovered and reused.

To sum up, due to the adoption of the above-mentioned technical solutions, the beneficial effects of the present invention are:

1. The NdFeB waste is selectively leached by hydrochloric acid and conversion agent as leaching agent, so that the rare earth is dissolved in the feed liquid while iron and boron are left in the slag and will not be dissolved, and the rare earth yield is above 98.6% , to achieve efficient recovery of valuable rare earths in NdFeB waste.

2. The process is simple, the process is short, the rare earth leaching rate is high, and the production operability is strong and pollution-free.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only It is a part of the embodiments of the present application, but not all of the embodiments. The components of the embodiments of the present application generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Thus, the following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the application as claimed, but is merely representative of selected embodiments of the application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

Example 1

A new method for recovering rare earth from NdFeB recycled material, comprising the following steps:

Step 1: Mixing: fully mix the NdFeB wastes in the form of powder, granular, block, mud, etc. to obtain NdFeB wastes that are dry and wet evenly and are convenient for abrasive sample preparation;

Step 2: Grinding and sample preparation: Weigh 500 g of the NdFeB waste obtained in Step 1 and add it to the sample preparation machine for grinding to obtain NdFeB waste powder;

Step 3: sieving and slurrying: sieve the NdFeB waste powder obtained in step 2 with a 200-mesh sample to obtain the oversize and undersize, and detect the content of rare earth and iron in the undersize. The rare earth content is 26%, and the iron content is 67%. Put the material on the sieve into the sample making machine to continue grinding, weigh 200g of the material under the sieve, and add 350ml of water to make it into a slurry;

Step 4: Leaching: slowly add 120 ml of hydrochloric acid with a concentration of 30% to the slurry obtained in step 3, and then slowly add 156 ml of hydrogen peroxide with a concentration of 30% after the hydrochloric acid is added, and the rare earth leaching is controlled at a temperature of 50%. ℃, the reaction time is 2h;

Step 5: flocculation and clarification: the feed liquid obtained in step 4 is heated to 90 ℃, then ammonium bicarbonate is added, the pH value of the feed liquid is adjusted to 3, and after waiting for 10 minutes, polyacrylamide is added to the feed liquid for flocculation and clarification;

Step 6: filter and wash the residue: filter the feed solution obtained in step 5 to obtain filter residue and rare earth chloride feed solution, and rinse the filter residue until the rare earth concentration in the washing water is less than 0.5g/L, and then stop leaching to obtain feed residue and washing water with low concentration of rare earth chloride, the rare earth chloride feed liquid can be used for extraction and separation to obtain single rare earth oxide, and the washing water with low concentration of rare earth chloride is used as sizing water in step three;

Step 7: Detection: Drying and weighing the slag and detecting the grade of rare earth, and calculating the recovery rate of rare earth according to the detection result, the quality of the detected slag is 146g, the grade of rare earth is 0.43%, and the recovery rate of rare earth is 98.8%.

Example 2

Step 1: Mixing: fully mix the NdFeB wastes in the form of powder, granular, block, mud, etc. to obtain NdFeB wastes that are dry and wet evenly and are convenient for abrasive sample preparation;

Step 2: Grinding and sample preparation: Weigh 500 g of the NdFeB waste obtained in Step 1 and add it to the sample preparation machine for grinding to obtain NdFeB waste powder;

Step 3: sieving and slurrying: sieve the NdFeB waste powder obtained in step 2 with a 200-mesh sample to obtain the oversize and undersize, and detect the content of rare earth and iron in the undersize. The rare earth content is 28%, and the iron content is 65%. Put the material on the sieve into the sample making machine to continue grinding, weigh 200g of the material under the sieve, and add 380ml of water to make it into a slurry;

Step 4: Leaching: Slowly add 140ml of hydrochloric acid with a concentration of 30% to the slurry obtained in Step 3, and then slowly add 160ml of hydrogen peroxide with a concentration of 30% after the hydrochloric acid is added to leaching the rare earth, and the temperature during this process is controlled to be 53℃, the reaction time is 1.8h;

Step 5: flocculation and clarification: the feed liquid obtained in step 4 is heated to 88 °C, then ammonium bicarbonate is added, the pH value of the feed liquid is adjusted to 3.5, and after waiting for 13 minutes, polyacrylamide is added to the feed liquid for flocculation and clarification;

Step 6: filter and wash the residue: filter the feed solution obtained in step 5 to obtain filter residue and rare earth chloride feed solution, and rinse the filter residue until the rare earth concentration in the washing water is less than 0.5g/L, and then stop leaching to obtain feed residue and washing water with low concentration of rare earth chloride, the rare earth chloride feed liquid can be used for extraction and separation to obtain single rare earth oxide, and the washing water with low concentration of rare earth chloride is used as sizing water in step three;

Step 7: Detection: drying and weighing the slag and detecting the grade of rare earth, and calculating the recovery rate of rare earth according to the detection results.

Example 3

Step 1: Mixing: fully mix the NdFeB wastes in the form of powder, granular, block, mud, etc. to obtain NdFeB wastes that are dry and wet evenly and are convenient for abrasive sample preparation;

Step 2: Grinding and sample preparation: Weigh 500 g of the NdFeB waste obtained in Step 1 and add it to the sample preparation machine for grinding to obtain NdFeB waste powder;

Step 3: sieving and slurrying: sieve the NdFeB waste powder obtained in step 2 with a 200-mesh sample to obtain the oversize and undersize, and detect the content of rare earth and iron in the undersize. The rare earth content is 30%, and the iron content is 66%. Put the material on the sieve into the sample making machine to continue grinding, weigh 200g of the material under the sieve, and add 400ml of water to make it into a slurry;

Step 4: Leaching: slowly add 150 ml of hydrochloric acid with a concentration of 30% to the slurry obtained in step 3, and then slowly add 172 ml of hydrogen peroxide with a concentration of 30% after the hydrochloric acid is added to leaching the rare earth, and the temperature during this process is controlled to be 55℃, the reaction time is 1.5h;

Step 5: flocculation and clarification: the feed liquid obtained in step 4 is heated to 85 ℃, then ammonium bicarbonate is added, the pH value of the feed liquid is adjusted to 3.5, and after waiting for 15 minutes, polyacrylamide is added to the feed liquid for flocculation and clarification;

Step 6: filter and wash the residue: filter the feed solution obtained in step 5 to obtain filter residue and rare earth chloride feed solution, and rinse the filter residue until the rare earth concentration in the washing water is less than 0.5g/L, and then stop leaching to obtain feed residue and washing water with low concentration of rare earth chloride, the rare earth chloride feed liquid can be used for extraction and separation to obtain single rare earth oxide, and the washing water with low concentration of rare earth chloride is used as sizing water in step three;

Step 7: Detection: drying and weighing the slag and detecting the grade of rare earth, and calculating the recovery rate of rare earth according to the detection result.

Comparative Example 1

This comparative example is the comparative example of Example 3, only quantitative hydrochloric acid is added in this comparative example, and no conversion agent is added.

Step 1: Mixing: fully mix the NdFeB wastes in the form of powder, granular, block, mud, etc. to obtain NdFeB wastes that are dry and wet evenly and are convenient for abrasive sample preparation;

Step 2: Grinding and sample preparation: Weigh 500 g of the NdFeB waste obtained in Step 1 and add it to the sample preparation machine for grinding to obtain NdFeB waste powder;

Step 3: sieving and slurrying: sieve the NdFeB waste powder obtained in step 2 with a 200-mesh sample to obtain the oversize and undersize, and detect the content of rare earth and iron in the undersize. The rare earth content is 30%, and the iron content is 66%. Put the material on the sieve into the sample making machine to continue grinding, weigh 200g of the material under the sieve, and add 400ml of water to make it into a slurry;

Step 4: leaching: slowly add 150ml of hydrochloric acid with a concentration of 30% to the slurry obtained in step 3, control the temperature during this process to be 55°C, and the reaction time to be 1.5h;

Step 5: flocculation and clarification: after testing that the pH in the feed liquid is 4.5-5.0, polyacrylamide is added to the first feed liquid for flocculation and clarification to obtain the second feed liquid;

Step 6: filter and wash the residue: filter the feed solution obtained in step 5 to obtain filter residue and rare earth chloride feed solution, and rinse the filter residue until the rare earth concentration in the washing water is less than 0.5g/L, and then stop leaching to obtain feed residue and washing water with low concentration of rare earth chloride, the rare earth chloride feed liquid can be used for extraction and separation to obtain single rare earth oxide, and the washing water with low concentration of rare earth chloride is used as sizing water in step three;

Step 7: Detection: drying and weighing the slag and detecting the grade of rare earth, and calculating the recovery rate of rare earth according to the detection results.

The recovery rate of rare earth in this comparative example is much lower than that of Example 3. Since only 150 ml of hydrochloric acid was added in Comparative Example 1, most of the solids were not dissolved after the dissolution was completed, so the pH value of the system was between 5.0 or more, so no need to heat up and adjust PH.

Comparative Example 2

This comparative example is also the comparative example of Example 3, and in this comparative example, only excess hydrochloric acid is added, and no conversion agent is added.

Step 1: Mixing: fully mix the NdFeB wastes in the form of powder, granular, block, mud, etc. to obtain NdFeB wastes that are dry and wet evenly and are convenient for abrasive sample preparation;

Step 2: Grinding and sample preparation: Weigh 500 g of the NdFeB waste obtained in Step 1 and add it to the sample preparation machine for grinding to obtain NdFeB waste powder;

Step 3: sieving and slurrying: sieve the NdFeB waste powder obtained in step 2 with a 200-mesh sample to obtain the oversize and undersize, and detect the content of rare earth and iron in the undersize. The rare earth content is 30%, and the iron content is 66%. Put the material on the sieve into the sample making machine to continue grinding, weigh 200g of the material under the sieve, and add 400ml of water to make it into a slurry;

Step 4: leaching: slowly add 800ml of hydrochloric acid with a concentration of 30% to the slurry to leaching rare earth, control the temperature in this process to be 85°C, and the reaction time to be 20min;

Step 5: flocculation and clarification: control the temperature to 85°C, add 600ml of hydrogen peroxide to the feed solution obtained in step 4 to oxidize the ferrous iron to ferric iron, and then slowly add 500ml of concentrated ammonia water to adjust the pH to 3.5 to remove the ferric iron ions, After waiting for 20min, add polyacrylamide to the liquid for flocculation and clarification;

Step 6: filter and wash the residue: filter the feed solution obtained in step 5 to obtain filter residue and rare earth chloride feed solution, and rinse the filter residue until the rare earth concentration in the washing water is less than 0.5g/L, and then stop leaching to obtain feed residue and washing water with low concentration of rare earth chloride, the rare earth chloride feed liquid can be used for extraction and separation to obtain single rare earth oxide, and the washing water with low concentration of rare earth chloride is used as sizing water in step three;

Step 7: Detection: Drying and weighing the slag and detecting the grade of rare earth, and calculating the recovery rate of rare earth according to the detection result, the quality of the detected slag is 148g, the grade of rare earth is 0.65%, and the recovery rate of rare earth is 98.4%.

In this comparative example, although the recovery rate of rare earth is relatively high, iron and rare earth are leached into the feed liquid at the same time, and the consumption of hydrochloric acid, hydrogen peroxide, and ammonia water is relatively large, and the cost is relatively high.

The above examples and comparative examples show that, compared with the prior art, the present invention selectively leaches rare earths from NdFeB waste materials through hydrochloric acid and conversion agent as leaching agents, so that rare earths are dissolved into the feed liquid and both iron and boron remain. It is not dissolved in the slag, and its rare earth yield is above 98.6%, which realizes the efficient recovery of valuable rare earths in NdFeB waste, simple process, short process, high rare earth leaching rate, strong production operability and no pollution, and lower cost.

The above-mentioned embodiments only represent specific implementations of the present application, and the descriptions thereof are specific and detailed, but should not be construed as limiting the protection scope of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the technical solution of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application.

Claims (10)

1. a novel method of reclaiming rare earth from NdFeB reclaimed material, is characterized in that: comprise the following steps: Step 1: Mixing: Mixing various forms of NdFeB wastes to obtain NdFeB wastes that are dry and wet evenly and are convenient for abrasive sample preparation; Step 2: Grinding and preparing samples: adding the NdFeB waste obtained in Step 1 to the sample preparation machine for grinding to obtain NdFeB waste powder; Step 3: sieving and sizing: sieve the NdFeB waste powder obtained in step 2 by sizing to obtain oversize and undersize, detect the content of rare earth and iron in the undersize, and sieve the undersize. Make a slurry with water; Step 4: leaching: slowly add hydrochloric acid to the slurry obtained in step 3, and then slowly add the conversion agent after the addition of the hydrochloric acid to leaching the rare earth; Step 5: flocculation and clarification: the feed liquid obtained in step 4 is heated to 85-90 ℃, then add pH adjuster, adjust the pH value of feed liquid to 3.0-3.5, wait for 10-15min, add flocculant to the feed liquid to flocculate clarify; Step 6: filter and wash the residue: filter the feed solution obtained in step 5 to obtain filter residue and rare earth chloride feed solution, and rinse the filter residue until the rare earth concentration in the washing water is less than 0.5g/L, and then stop leaching to obtain feed residue and washing water with low concentration of rare earth chloride; Step 7: Detection: drying and weighing the slag and detecting the grade of rare earth, and calculating the recovery rate of rare earth according to the detection result. 2. a kind of novel method of reclaiming rare earth from neodymium iron boron reclaimed material according to claim 1, is characterized in that; the concentration of hydrochloric acid described in step 4 is 30%, and described undersize and the hydrochloric acid added are 30%. The mass ratio is 1:(0.69-0.86). 3. a kind of novel method of reclaiming rare earth from neodymium iron boron reclaimed material according to claim 1, is characterized in that: described in the step 4, the conversion agent is hydrogen peroxide, and the concentration of described hydrogen peroxide is 28-30%, so The mass ratio of the undersize and the added hydrogen peroxide is 1:(0.78-0.85). 4. A new method for recovering rare earth from NdFeB reclaimed material according to claim 1, characterized in that: the temperature of leaching in step 4 is 50-55°C, and the time is 1.5-3.5h. 5. a kind of novel method of reclaiming rare earth from neodymium iron boron reclaimed material according to claim 1, is characterized in that: pH regulator described in step 5 is ammonium bicarbonate. 6 . The novel method for recovering rare earths from NdFeB reclaimed material according to claim 1 , wherein the flocculant in step 5 is polyacrylamide. 7 . 7. a kind of novel method of reclaiming rare earth from neodymium iron boron reclaimed material according to claim 1, is characterized in that: in step 3, the obtained oversize material is added in the sample making machine and continues grinding. 8. a kind of novel method of reclaiming rare earth from NdFeB reclaimed material according to claim 1, is characterized in that: in step 3, the mass ratio of undersize and added water is 1:(1.75-2). 9 . The novel method for recovering rare earths from NdFeB reclaimed material according to claim 1 , wherein the sample sieve described in step 3 is a 200-mesh sample sieve. 10 . 10. A new method for recovering rare earths from NdFeB reclaimed material according to claim 1, characterized in that: the washing water with low concentration of rare earth chloride obtained in step 6 is used as sizing water in step 3.

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