Method for stably producing high-grade rare earth concentrate in bayan obo ore

Abstract

The invention discloses a method for stably producing high-grade rare earth ore concentrate in bayan obo ore, which comprises the following steps of: 1, feeding the bayan obo ore into a crushing process and crushing the ore to 12-0mm by adopting a crushing closed-loop screening process, and 2, feeding the crushed material into a continuous ore grinding process which comprises two processes, the method comprises the following steps: step 1, carrying out a magnetic separation process to separate ferromagnetic minerals so that the grade of rare earth minerals reaches 6-8%, step 2, carrying out desliming and concentration operation through a thickener, and carrying out overflow and taking out gangue minerals through the thickener due to small specific gravity, fine granularity and slow settling velocity so that the gangue minerals are separated out and the grade of the rare earth minerals reaches 6-8%, and step 3, carrying out desliming and concentration operation through the thickener. By means of the method, part of gangue substances in the rare earth concentrate are further reduced, the grade of the rare earth raw ore reaches 8%-10%, the concentration of the rare earth raw ore ranges from 60% to 62%, the grade of rare earth flotation can be improved, part of agents can be saved, and therefore the production cost of the rare earth concentrate is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of ore dressing, and in particular to a method for stably producing high-grade rare earth concentrate in the Bayan Obo mine. Background Art

[0002] At present, the research on the beneficiation technology of 65% rare earth concentrate has only undergone multi-stage beneficiation, and has not carried out grinding, washing, desludging, and de-refining treatment on the coarse-grained and low-dissociation medium ore, resulting in a long beneficiation process, making the internal tailings grade high and difficult to reduce to below 2%, and the rare earth medium ore with a grade of 45%-55% has not been reprocessed, so that the gangue minerals are also seriously coated with reagents due to multiple selections, which reduces the flotation efficiency, increases the amount of flotation reagents, and makes it difficult to control the flotation conditions. When producing high-grade rare earth concentrate, the recovery rate will naturally be very low, making it difficult to prepare high-grade and high-recovery rare earth concentrates with the original beneficiation technology.

[0003] As the main mining base of light rare earths in China, Bayan Obo is a rare super-large deposit of iron, rare earths, fluorite, niobium, scandium and other mineral resources coexisting in the world. The rare earth oxide reserves are about 100 million tons and the industrial reserves are 43 million tons.

[0004] At present, the average rare earth grade of Bayan Obo Mine is 4%-6%. First, magnetic separation is used to recover iron concentrate, and then flotation is used to recover rare earth concentrate. It is difficult to stably achieve a grade of more than 60% for rare earth concentrate. The beneficiation process of rare earth concentrate does not grind the rougher tailings with coarser particle size and lower mineral dissociation degree, and does not wash or desludging the concentrated ore, resulting in a longer beneficiation process and a high grade of tailings. The recovery rate is low when producing high-grade rare earth concentrate, making it difficult to prepare high-grade and high-recovery rare earth concentrate with the original beneficiation process.

[0005] In view of the above factors, in order to meet the actual needs, a method for stably producing high-grade rare earth concentrate in the Bayan Obo mine was developed, so that the grade of rare earth concentrate can be stabilized at more than 60% during production. The grade of rare earth concentrate with a grade of about 50% can be stably increased to more than 60% through a 1.7T strong magnetic machine, and the grade of rare earth flotation concentrate only needs to be controlled at about 50%. It can not only improve the grade of rare earth flotation, but also save some reagents, thereby reducing the production cost of rare earth concentrate. Summary of the invention

[0006] In order to make up for the deficiencies of the prior art, the present invention provides a method for stably producing high-grade rare earth concentrate from Bayan Obo ore. The rare earth concentrate with a grade of more than 53% obtained by the method of one roughing and two cleaning in actual production is fed into a cylindrical screen by a concentrate pump to remove large impurities in the rare earth concentrate, and then the rare earth concentrate enters a 1.7T high-intensity magnetic separator by gravity flow, and rare earth concentrate with a grade of more than 60% can be stably output, which can save some reagents and reduce the production cost of rare earth concentrate.

[0007] The purpose of the present invention is to provide a method for stably producing high-grade rare earth concentrate from Bayan Obo ore, which specifically includes the following steps;

[0008] In the first step, the Bayan Obo ore is fed into a crushing process, and the ore is crushed to 12mm - 0mm by a closed-circuit screening crushing process;

[0009] In the second step, the crushed material is fed into a continuous grinding process. The continuous grinding process includes two processes to obtain Bayan Obo ore with more than 90% -200 mesh;

[0010] In the third step, it enters a magnetic separation process to separate ferromagnetic minerals, so that the grade of rare earth ore reaches between 6% and 8%;

[0011] In the fourth step, a thickener is used for de-sludging and concentration operations. Gangue minerals have a small specific gravity, fine particle size, and slow sedimentation speed, and are carried out by the overflow of the thickener, further reducing some gangue substances in the rare earth concentrate, so that the grade of the rare earth raw ore reaches 8% - 10%, and the concentration is between 60% and 62%;

[0012] In the fifth step, a method of one roughing, two scavenging, and two cleaning is used to stably output rare earth concentrate with a grade of more than 60%. The specific operations are as follows;

[0013] Salicylhydroxamic acid is selected as the rare earth collector, and water glass is used as the inhibitor. The temperature is between 70 - 80°C. Stirring tanks with different numbers are set. Heating operations are carried out in the first stirring tank to reach the flotation temperature. Water glass is added to the second stirring tank to inhibit the floating of iron and gangue minerals. The collector is added to the third stirring tank. After roughing, the rare earth grade is between 30% and 35%;

[0014] A small amount of collector is added in the first cleaning. After the first cleaning, the rare earth grade is between 45% and 48%. No flotation reagents are added in the second cleaning. After the second cleaning, the grade of the rare earth concentrate is more than 50%. Then, the rare earth concentrate with a grade of more than 50% is fed into the thickener again for re-de-sludging to obtain rare earth concentrate with a grade of about 53%. Then, the pulp concentration is adjusted to about 30% by pulp adjustment, and it is fed into a cylindrical screen by a concentrate pump to remove large impurities in the rare earth concentrate;

[0015] Then, utilize the self-flow of the elevation difference to make the rare earth concentrate enter the 1.7T high-intensity magnetic separator. By taking advantage of the weak magnetism of rare earth, more than 60% of the rare earth concentrate can be stably output. The grade of the medium ore in the high-intensity magnetic separation is about 50% and can enter the filtration system.

[0016] Further, feed the crushed material into the first grinding process and the second grinding process for treatment. After passing through a rod mill and a spiral classifier in the first grinding process, the particle size reaches more than 68%. Then enter the second grinding process, which consists of a ball mill and a hydrocyclone. By connecting the above two groups of grinding processes in series, Bayan Obo ore with a particle size of -200 mesh over 90% can be obtained.

[0017] Further, in step five, add the rare earth raw ore in step four to the stirring system, add water to mix and adjust the pulp, and start stirring. While stirring, add water glass in sequence. After rough selection, the rare earth grade is between 30% and 35%.

[0018] Further, for the tailings after rough selection with a tailing grade of 4%, enter the scavenging operation again. 10% of the rare earth concentrate obtained from scavenging is returned to the original ore shaft, and 2% of the rare earth tailings are discarded.

[0019] Further, during scavenging, the rough selection tailings are ground and classified to obtain a product with a particle size of -300 mesh of 76%. After scavenging, add the tailings after grinding and classification to the stirring flotation cell, add water to mix and adjust the pulp, and stir to control the pulp mass concentration at 50% and the pulp temperature at 50°C;

[0020] While stirring, add 0.2 - 0.5 kg / t of water glass in sequence. During scavenging, the pH of the pulp is 9.1. The final tailings with a rare earth grade less than 1.3% are discharged, and the scavenging middlings are returned to the rough selection cell.

[0021] Further, scavenging is set twice. After the first rough selection, the tailings are subjected to the first scavenging. Add the rough selection tailings to the flotation cell, add water to mix and adjust the pulp, and stir to control the pulp mass concentration at 50% and the pulp temperature at 50°C;

[0022] After the first scavenging, it is returned to the rough selection cell to continue the next rough selection. The product tailings after the second scavenging are returned to the first scavenging.

[0023] Further, the products of scavenging are scavenging concentrate and scavenging tailings. The rare earth grade of the scavenging concentrate is 60%. It is subjected to the next step of washing, de-sludging, and de-dosing. The scavenging tailings are returned to the first-stage rough selection cell to continue the next rough selection.

[0024] Further, the average particle size of the flotation concentrate is -200 mesh at 97.84%, and the average concentration is 29.79%.

[0025] Application of a method for stably producing high-grade rare earth concentrate from Bayan Obo ore, characterized in that: it is applicable to the production of high-grade rare earth concentrate from Bayan Obo. By utilizing the weak magnetism of rare earth, more than 60% of rare earth concentrate can be stably output. The grade of medium magnetic concentrate is about 50% and can enter the filtration system. High-grade rare earth concentrate can reduce the smelting cost during rare earth smelting, reduce waste discharge, has good process guiding effect on the resumption of production of rare earth smelting enterprises, and significantly improves the recovery rate of rare earth.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] The average particle size of flotation concentrate of the present invention is -200 mesh at 97.84%, and the average concentration is 29.79%, meeting the separation conditions of the high-intensity magnetic separator. By reselecting rare earth concentrate through the high-intensity magnetic separator, the concentrate grade can be well improved, with an average increase from 52.55% to 61.10%, an increase of 8.55%.

[0028] By reselecting rare earth concentrate through the high-intensity magnetic separator in the present invention, the tailings and medium magnetic concentrate have relatively high grades. The average grade of tailings is 47.97%, a decrease of 4.58% compared with the original ore grade of 52.55%; the average grade of medium magnetic concentrate is 56.22%, an increase of 3.67% compared with the original ore grade of 52.55%.

[0029] There are 8 shifts in total with flotation concentrate greater than 53% in the present invention. The indexes of the high-intensity magnetic separator are: average original ore grade 56.45%, average concentrate grade 62.73%, average tailings grade 53.85%, average medium magnetic concentrate grade 60.00%, belt concentrate grade 58.69%, and output 139.93t; there are 21 shifts in total with flotation concentrate less than 53%. The indexes of the high-intensity magnetic separator are: average original ore grade 51.06%, average concentrate grade 60.48%, average tailings grade 45.73%, average medium magnetic concentrate grade 54.73%, belt concentrate grade 60.11%, and output 244.19t.

[0030] The present invention can stably maintain the grade of rare earth concentrate above 60% during production. Through a 1.7T high-intensity magnetic separator, rare earth concentrate with a grade of about 50% can be stably increased to above 60%. As long as the grade of rare earth flotation concentrate is controlled at about 50%, it can not only improve the grade of rare earth flotation but also save a part of the reagent, thereby reducing the production cost of rare earth concentrate. Detailed implementation manners

[0031] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention and make the above-mentioned objects, features, and advantages of the present invention more obvious and understandable, the following further explains the detailed implementation manners of the present invention.

[0032] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the values between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0033] A method for stably producing high-grade rare earth concentrate from Bayan Obo ore, specifically including the following steps;

[0034] In the first step, feed the Bayan Obo ore into the crushing process, and use the closed-circuit screening crushing process to crush the ore to 12mm - 0mm;

[0035] In the second step, feed the crushed material into the continuous grinding process. The continuous grinding process includes two processes to obtain Bayan Obo ore with more than 90% -200 mesh;

[0036] In the third step, enter the magnetic separation process to separate ferromagnetic minerals, so that the grade of rare earth ore products reaches between 6% and 8%;

[0037] In the fourth step, carry out the operation of de-sludging and thickening by a thickener. Gangue minerals, due to their small specific gravity, fine particle size, and slow settling speed, are carried out by the thickener overflow, further reducing some gangue substances in the rare earth concentrate, so that the grade of rare earth raw ore reaches 8% - 10%, and the concentration is between 60% - 62%;

[0038] In the fifth step, use the method of one roughing, two scavengings, and two cleanings to stably output rare earth concentrate of more than 60%. The specific operation is as follows;

[0039] Select salicylhydroxamic acid as the rare earth collector and water glass as the inhibitor. The temperature is between 70 - 80 °C. Set stirring tanks with different numbers. Carry out heating operation in the first stirring tank to reach the flotation temperature. Add water glass in the second stirring tank to inhibit the floating of iron and gangue minerals. Add the collector in the third stirring tank. After roughing, the rare earth grade is between 30% and 35%;

[0040] Add a small amount of collector in the first cleaning. After the first cleaning, the rare earth grade is between 45% and 48%. No flotation reagent is added in the second cleaning. After the second cleaning, the grade of rare earth concentrate is more than 50%. Then, the rare earth concentrate with a grade of more than 50% is fed into the thickener again for re-de-sludging to obtain rare earth concentrate with a grade of about 53%. Then, adjust the pulp to keep the pulp concentration at about 30%, and use the concentrate pump to send it into the cylindrical screen to clean the large impurities in the rare earth concentrate;

[0041] Then, by taking advantage of the self-flow of the height difference, the rare earth concentrate is fed into a 1.7T high-intensity magnetic separator. By utilizing the weak magnetism of rare earth, more than 60% of the rare earth concentrate can be stably output. The grade of the medium ore in the high-intensity magnetic separation is about 50% and can enter the filtration system.

[0042] The crushed materials are fed into the first grinding process and the second grinding process for treatment. After passing through a rod mill and a spiral classifier in the first grinding process, the particle size reaches more than 68%. Then it enters the second grinding process, which consists of a ball mill and a hydrocyclone. By connecting these two grinding processes in series, Bayan Obo ore with a particle size of less than 200 mesh of more than 90% can be obtained.

[0043] In step 5, the rare earth raw ore from step 4 is added to the stirring system, water is added for mixing and pulp adjustment, and stirring is started. While stirring, water glass is added successively. After rough selection, the rare earth grade is between 30% and 35%.

[0044] After rough selection, the tailings have a grade of 4%. They enter the scavenging operation again, and 10% of the rare earth concentrate obtained from scavenging is returned to the original ore shaft, and 2% of the rare earth tailings are discarded.

[0045] During scavenging, the rough selection tailings are ground and classified to obtain a product with a particle size of -300 mesh of 76%. After scavenging, the tailings after grinding and classification are added to the stirring flotation cell, water is added for mixing and pulp adjustment, and stirring is carried out to control the pulp mass concentration at 50% and the pulp temperature at 50°C.

[0046] While stirring, 0.2 - 0.5 kg / t of water glass is added successively. During scavenging, the pH of the pulp is 9.1. The final tailings with a rare earth grade of less than 1.3% are discharged, and the scavenging middlings are returned to the rough selection cell.

[0047] The products of scavenging are scavenging concentrate and scavenging tailings. The rare earth grade of the scavenging concentrate is 60%. It is subjected to the next step of washing, de-sludging, and de-drugging. The scavenging tailings are returned to the first-stage rough selection cell to continue the next rough selection.

[0048] Scavenging is set twice. After the first rough selection, the tailings are subjected to the first scavenging. The rough selection tailings are added to the flotation cell, water is added for mixing and pulp adjustment, and stirring is carried out to control the pulp mass concentration at 50% and the pulp temperature at 50°C.

[0049] After the first scavenging, it is returned to the rough selection cell to continue the next rough selection. The tailings of the products after the second scavenging are returned to the first scavenging.

[0050] The average particle size of the flotation concentrate is -200 mesh at 97.84%, and the average concentration is 29.79%.

[0051] The present invention feeds the Bayan Obo ore into a crushing process, uses a closed-circuit screening process for crushing the ore, and then enters a continuous grinding process. After passing through a rod mill and a hydrocyclone, the particle size reaches over 68%. Then it enters a grinding process consisting of a ball mill and a hydrocyclone in a group. By connecting two groups of grinding processes in series, Bayan Obo ore with a particle size of -200 mesh over 90% can be obtained. It enters a magnetic separation process to separate ferromagnetic minerals, so that the grade of the rare earth ore product reaches between 6% and 8%. Then, a thickener is used for desliming and thickening operations. Gangue minerals have a small specific gravity, fine particle size, and slow settling speed, and are carried out by the overflow of the thickener, further reducing some gangue substances in the rare earth concentrate, so that the grade of the rare earth raw ore reaches 8% - 10% and the concentration is between 60% and 62%.

[0052] The rare earth minerals flotation of the present invention can obtain rare earth concentrate over 60%, reducing the ore volume for subsequent treatment. And for the rare earth concentrate with a yield of 45% - 55%, a washing, desliming, and de-dosing process is carried out to purify the surface properties of the minerals from the raw materials, avoiding the surface contamination of the minerals caused by the previous multi-stage iron and rare earth separation processes, which makes it difficult to improve the grade of the minerals. Moreover, it saves flotation reagents, reduces the number of flotation process stages, is easy to operate and control.

[0053] The application of a method for stably producing high-grade rare earth concentrate from Bayan Obo ore is suitable for the production of high-grade rare earth concentrate in Bayan Obo. Utilizing the weak magnetism of rare earth, rare earth concentrate over 60% can be stably output. The grade of the medium magnetic concentrate is about 50% and can enter the filtration system. High-grade rare earth concentrate can reduce the smelting cost during rare earth smelting, reduce waste emissions, has good process guiding significance for the resumption of production of rare earth smelting enterprises, and significantly improves the recovery rate of rare earth.

[0054] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed by the present invention.

[0055] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for stably producing high-grade rare earth concentrate in Bayan Obo ore, characterized in that: Specifically, it includes the following steps; In the first step, send the Bayan Obo ore into the crushing process, and use the closed-circuit screening crushing process to crush the ore to 12mm - 0mm; In the second step, send the crushed material into the continuous grinding process. The continuous grinding process includes two processes to obtain Bayan Obo ore with over 90% -200 mesh; In the third step, enter the magnetic separation process to separate ferromagnetic minerals, so that the rare earth ore grade reaches between 6% and 8%; In the fourth step, carry out the desliming and thickening operation through a thickener. Gangue minerals have a small specific gravity, fine particle size, and slow settling speed, and are carried out by the overflow of the thickener, further reducing some gangue substances in the rare earth concentrate, so that the rare earth raw ore grade reaches 8% - 10%, and the concentration is between 60% and 62%; In the fifth step, use the method of one roughing, two scavenging, and two cleaning to obtain rare earth concentrate with a stable output of over 60%. The specific operation is as follows; Select salicylhydroxamic acid as the rare earth collector and water glass as the inhibitor. The temperature is between 70 - 80°C. Set stirring tanks with different numbers. Carry out heating operation in the first stirring tank to reach the flotation temperature. Add water glass to the second stirring tank to inhibit the floating of iron and gangue minerals. Add the collector to the third stirring tank. After roughing, the rare earth grade is between 30% and 35%; Add a small amount of collector in the first cleaning. After the first cleaning, the rare earth grade is between 45% and 48%. No flotation reagent is added in the second cleaning. After the second cleaning, the rare earth concentrate grade is over 50%. Then send the rare earth concentrate with a grade of over 50% into the thickener again for re-desliming to obtain rare earth concentrate with a grade of about 53%. Then adjust the pulp to keep the pulp concentration at about 30%, and use a concentrate pump to send it into a cylindrical screen to clean large impurities in the rare earth concentrate; Then use the head difference to make the rare earth concentrate flow into a 1.7T high-intensity magnetic separator by gravity. Utilize the weak magnetism of rare earth to stably output rare earth concentrate of over 60%. The grade of the high-intensity magnetic separator middlings is about 50% and can enter the filtration system.

2. The method for stably producing high-grade rare earth concentrate in Bayan Obo Mine according to claim 1, characterized in that: Send the crushed material into the first grinding process and the second grinding process for treatment. After passing through a rod mill and a spiral classifier in the first grinding process, the particle size reaches over 68%. Then enter the second grinding process, which consists of a ball mill and a hydrocyclone in a set of grinding processes. Connect the above two sets of grinding processes in series to obtain Bayan Obo ore with over 90% -200 mesh.

3. The method for stably producing high-grade rare earth concentrate in Bayan Obo Mine according to claim 2, wherein: In step 5, add the rare earth raw ore from step 4 into the stirring system, add water to mix and adjust the pulp, and start stirring. While stirring, add water glass in sequence. After roughing, the rare earth grade is between 30% and 35%.

4. The method for stably producing high-grade rare earth concentrate in Bayan Obo ore according to claim 3, characterized in that: For the tailings after roughing, the tailings grade is 4%. Enter the scavenging operation again to obtain 10% rare earth concentrate from scavenging and return it to the original ore main shaft, and discard 2% rare earth tailings.

5. The method for stably producing high-grade rare earth concentrate in Bayan Obo ore as claimed in claim 3, wherein: During scavenging, the roughing tailings are ground and classified to obtain a product of 76% -300 mesh and then scavenged. Add the tailings after grinding and classification into the stirring flotation cell, add water to mix and adjust the pulp, stir, and control the pulp mass concentration at 50%, and the pulp temperature is 50°C; While stirring, 0.2 - 0.5 kg / t of water glass is added successively. During the scavenging process, the pH of the pulp is 9.1, and the final tailings are discharged with a rare earth grade of less than 1.3%. The scavenged middlings are returned to the rougher cell.

6. The method for stably producing high-grade rare earth concentrate in Bayan Obo ore as claimed in claim 5, characterized in that: The products of scavenging are scavenged concentrate and scavenged tailings. The rare earth grade of the scavenged concentrate is 60%. It is then subjected to the next step of washing, desliming, and dephlegming. The scavenged tailings are returned to the first-stage rougher cell for the next rougher separation.

7. The method for stably producing high-grade rare earth concentrate in Bayan Obo ore, according to claim 6, is characterized in that: Scavenging is set twice. After the first cleaning, the tailings are subjected to the first scavenging. The rougher tailings are added to the flotation cell, mixed with water for pulp adjustment, and stirred to control the pulp mass concentration at 50% and the pulp temperature at 50 °C. After the first scavenging, it is returned to the rougher cell for the next rougher separation. The tailings of the products after the second scavenging are returned to the first scavenging.

8. The method for stably producing high-grade rare earth concentrate in Bayan Obo Mine according to claim 7, characterized in that: The average particle size of the flotation concentrate is -200 mesh at 97.84%, and the average concentration is 29.79%.

9. Use of a method for stably producing high-grade rare earth concentrate in Bayan Obo ore according to any one of claims 1-8, characterized in that: It is applicable to the production of high-grade rare earth concentrate from Bayan Obo. By utilizing the weak magnetism of rare earths, rare earth concentrate with a grade of over 60% can be stably output. The grade of the strong magnetic middlings is about 50% and can enter the filtration system. The high-grade rare earth concentrate can reduce the smelting cost during rare earth smelting, reduce waste emissions, has good process guiding significance for the resumption of production of rare earth smelting enterprises, and significantly improves the recovery rate of rare earths.