Method for closed-circuit rare earth flotation with backwater

Abstract

The application provides a method for closed-circuit desliming and flotation of rare earths by using backwater, and relates to the technical field of water treatment, and comprises the following steps: S1, performing first desliming on raw ore slurry to obtain upper layer slurry and bottom layer slurry; S2, performing roughing on the bottom layer slurry to obtain roughing froth and roughing slurry; S3, performing scavenging on the roughing slurry to obtain scavenging tailings and scavenging froth; S4, performing first cleaning on the scavenging froth and the roughing froth to obtain first middlings and first cleaning froth; S5, performing second cleaning on the first cleaning froth to obtain second middlings and second cleaning froth; S6, performing second desliming on the second cleaning froth to obtain clean water of concentrate and rare earth concentrate; and S7, feeding the clean water of concentrate and the second middlings into raw ore slurry in the next experimental step S1 to continue rare earth flotation, so that the closed circuit is realized. The backwater is used for flotation production, and the quality and yield of the rare earth production concentrate are ensured.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a method for closed-loop de-drug flotation of rare earth elements using recycled water. Background Technology

[0002] The production targets for rare earth flotation at Baogang Baoshan Mining Company are a rare earth concentrate grade REO ≥ 58% and an operational recovery rate ≥ 50%. In the rare earth flotation process, recycled water is typically used as production water for closed-circuit flotation. The advantages of using recycled water include: 1. Reducing the amount of fresh water added, thus lowering production costs; 2. Recycled water carries some rare earth flotation reagents, which, when returned to the system, reduces the amount of new reagents used, further lowering production costs; 3. Recycling water reduces the discharge of mineral processing wastewater, contributing to environmental protection.

[0003] The recycled water from Baoshan Mining Company is the total recycled water from the entire "iron-rare earth-fluorite" beneficiation process. Specifically, it includes overflow water and filtration water generated during the operation of various thickening, grinding, and filtering equipment in the "iron-rare earth-fluorite" beneficiation process. This water flows to the tailings pond along with the tailings in the process, and after settling and clarification, it becomes production recycled water and is returned to the "iron-rare earth-fluorite" beneficiation system through pipelines for recycling. The entire "iron-rare earth-fluorite" beneficiation process involves first beneficiating iron from the raw ore, then using the tailings from iron beneficiation to beneficiate rare earths, and finally using the tailings from rare earth beneficiation to beneficiate. Some middlings and fluorite tailings are ultimately discharged. The quality of the production recycled water is unstable and is affected by factors such as whether production is normal, evaporation, and pH levels. Table 1 shows the water quality of the recycled water taken at a certain time point.

[0004] Table 1. Water quality indicators of production wastewater collected at a certain time point.

[0005]

[0006]

[0007] The reagents added in the entire iron-rare earth-fluorite beneficiation process include reverse flotation reagents for iron, such as oxidized paraffin soap and modified starch; forward flotation reagents for rare earth, such as hydroxamic acid; and forward flotation reagents for fluorite, such as oleic acid and linoleic acid. As the process runs longer, the amount of residual reagents and suspended solids in the reflux water increases, causing changes in reflux water quality and directly affecting beneficiation production indicators. The collector in fluorite flotation is the primary factor affecting rare earth flotation; residual reagents in the collector exist freely in the slurry water, continuously interfering with flotation. Practice shows that using the existing process and reagents, and conducting rare earth flotation on-site with reflux water, it is difficult to achieve the specified production targets, either with a concentrate grade REO ≤ 55% or an operating recovery rate ≤ 50%. Under otherwise unchanged conditions, the continuous accumulation of other types of residual reagents in the reflux water is the main factor interfering with rare earth flotation, and these residual reagents exist freely in the reflux water and are difficult to remove.

[0008] This invention is proposed to improve the quality of the return water and enhance the flotation separation index. Summary of the Invention

[0009] The purpose of this invention is to provide a closed-circuit desliming flotation method for rare earth elements using recycled water. In one embodiment, after desliming the raw ore slurry, a flotation test is conducted using water glass, KYR-1 rare earth collector, and No. 2 oil, involving a "one-stage roughing-one-stage scavenging-two-stage cleaning" process. The desliming water from the middlings cleaning process is combined and returned to the ore feed to achieve closed-circuit flotation. The separation parameters can stably achieve a concentrate grade REO ≥ 58% and an operating recovery rate ≥ 55%. This method solves the current difficulty of using recycled water for flotation production, ensuring the quality and yield of rare earth concentrates while reducing water and reagent costs and wastewater discharge, resulting in significant economic and social benefits.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] This invention provides a method for closed-circuit decanting and flotation of rare earth elements using recycled water, comprising the following steps:

[0012] S1: Perform the first desliming process on the raw ore slurry to obtain upper layer slime and lower layer slurry;

[0013] S2: Add water glass, collector and frother to the bottom slurry obtained in step S1, and carry out roughing to obtain roughing foam and roughing slurry;

[0014] S3: Collector and frother are added to the slurry after roughing to carry out scavenging to obtain scavenging tailings and scavenging foam;

[0015] S4: Add water glass and collector to the scavenging foam and roughing foam to carry out the first cleaning process and obtain the first middlings and the first cleaned foam.

[0016] S5: Perform a second refinement on the first selected foam to obtain the second medium ore and the second selected foam;

[0017] S6: Perform a second desliming process on the second selected foam to obtain concentrate desliming water and rare earth concentrate;

[0018] S7: The concentrate desliming water obtained in step S6 and the second intermediate ore obtained in step S5 are fed into the raw ore slurry in step S1 to continue rare earth flotation, thus achieving a closed circuit.

[0019] Furthermore, based on the above technical solution, the collector in steps S2, S3 and S4 is a rare earth collector, which includes KYR-1 type collector or LF8# collector.

[0020] And / or, the foaming agent in steps S2 and S3 includes one or more of No. 2 oil, H103 or J102, preferably No. 2 oil.

[0021] Furthermore, based on the above technical solution, the preparation method of the KYR-1 type collector includes the following steps:

[0022] Fatty acid methyl ester and hydroxylamine hydrochloride were heated and mixed to obtain KYR-1 type collector;

[0023] Preferably, the mass ratio of the fatty acid methyl ester to hydroxylamine hydrochloride is (1-3):(1-3);

[0024] Preferably, the heating and mixing temperature is 50-80℃, and the heating and mixing time is 2-4 hours.

[0025] Furthermore, based on the above technical solution, the concentration of the raw ore slurry in step S1 is 60-65%, and the temperature is 20-30℃.

[0026] Screening and analysis of raw ore slurry includes the following steps:

[0027] Multi-element analysis and particle size analysis were performed on the raw ore slurry to obtain the content ratio of each element in the raw ore and the distribution of minerals of different particle sizes in the raw ore.

[0028] Furthermore, based on the above technical solution, in step S1, the first desliming operation includes:

[0029] The raw ore slurry is placed in a container, production return water is added, and the mixture is stirred. After stirring, the mixture is allowed to stand to obtain the upper layer of ore mud and the lower layer of ore slurry.

[0030] The production wastewater refers to the total wastewater from the entire "iron-rare earth-fluorite" beneficiation process.

[0031] The mass-to-volume ratio of raw ore slurry to production recycled water is 1.6 g: 1 mL;

[0032] The stirring time is 3 to 5 minutes, and the stirring speed is 150 to 200 rad / min; after stirring, let it stand for 8 to 12 minutes.

[0033] Furthermore, based on the above technical solution, step S2 includes the following coarse selection process:

[0034] Pour the bottom slurry obtained in step S1 into the flotation cell, and then add water glass, collector and frother in sequence. After an interval of 2 to 3 minutes, start roughing and frothing to obtain roughing froth and roughing slurry.

[0035] The roughing temperature is 60-65℃, the pulp concentration of the bottom pulp is 60-65%, and the pH is 8-9.

[0036] The water glass, collector, and foaming agent should be added at intervals of 3-5 minutes.

[0037] The amount of water glass added is 10,000-15,000 mL / t, the amount of collector added is 50,000-70,000 mL / t, and the amount of foaming agent added is 100-150 mL / t.

[0038] The time for rough selection and foaming is 2 to 3 minutes.

[0039] Furthermore, based on the above technical solution, step S3 includes the scanning process as follows:

[0040] Collector and frother are added sequentially to the roughing pulp. After an interval of 2 to 3 minutes, scavenging and frothing are started to obtain scavenging foam and scavenging tailings.

[0041] The scavenging temperature is 60-65℃, the pulp concentration of the pulp after roughing is 50-55%, and the pH is 8-9.

[0042] The time interval between adding the collector and the foaming agent is 1 to 2 minutes;

[0043] The amount of collector added is 30,000 to 4,000 mL / t, and the amount of foaming agent added is 50 to 100 mL / t;

[0044] The time for the sweeping and skimming process is 2 to 3 minutes.

[0045] Furthermore, based on the above technical solution, in step S4, the first selection includes:

[0046] Pour the scavenging foam and roughing foam into the flotation cell, add water glass and collector in sequence, and after an interval of 1 to 2 minutes, start the first cleaning and frothing process to obtain the first middlings and the first cleaned foam.

[0047] The first fine-graining process is carried out at a temperature of 60–65℃, and the pulp concentration of the scavenging foam and roughing foam is 50–55%, with a pH of 8–9.

[0048] The time interval between adding water glass and the collector is 1 to 2 minutes;

[0049] The amount of water glass added is 1000-1200 mL / t, and the amount of collector added is 15000-20000 mL / t;

[0050] The first selection and scraping time is 3 to 4 minutes.

[0051] Furthermore, based on the above technical solution, in step S5, the second selection includes:

[0052] The first refined froth is poured into the flotation cell for a second refined froth removal process to obtain the second middlings and the second refined froth.

[0053] The second refining process takes place at a temperature of 60–65°C, while the first refining process produces a foam with a pulp concentration of 40–45% and a pH of 8–9.

[0054] The second round of fine-scraping and foaming should take 2-3 minutes.

[0055] Furthermore, based on the above technical solution, in step S6, the second desliming operation includes:

[0056] Pour the second selected foam into a container, add production return water, stir, and let it stand after stirring to obtain concentrate desliming water and rare earth concentrate.

[0057] The volume ratio of the second selected foam to the production recycled water is 1 mL: 3 mL.

[0058] The stirring refers to stirring using a JJ-1 type electric mechanical stirrer;

[0059] The stirring time is 3 to 5 minutes, and the stirring speed is 150 to 200 rad / min; after stirring, let it stand for 5 to 10 minutes.

[0060] The present invention provides a closed-circuit de-drug flotation method for rare earth elements using recycled water, which has the following advantages:

[0061] 1. In a specific embodiment of the present invention, the rare earth collectors contained in the closed-loop return water and concentrate desliming water in the process flow can interact with the residual fluorite flotation collectors in the raw ore slurry (i.e., tailings after iron ore beneficiation) and the fluorite flotation collectors in the return water used to dilute the raw ore slurry, producing substances that are easy to float. In the first desliming operation, the residual fluorite flotation collectors are dynamically removed by manually pouring out the upper layer of ore slime (laboratory method) or by overflowing through a thickener (actual production method), thereby reducing the interference of residual fluorite flotation collectors on flotation. After the raw ore is deslimed, a flotation test of "one roughing-one scavenging-two cleaning" is conducted using water glass, KYR-1 type rare earth collectors, and No. 2 oil. The desliming water from the middlings cleaning froth is combined and returned to the ore to achieve closed-loop flotation. The separation index can stably reach a concentrate grade REO≥58% and an operating recovery rate≥55%.

[0062] 2. In this invention, the residual KYR-1 rare earth collector in the closed-circuit returned slurry and concentrate desliming water can react with the fluorite flotation collector and iron flotation residues in the raw ore slurry. The residues are removed through overflow, reducing their interference with flotation. Simultaneously, it can combine with the slime in the raw ore, removing it through overflow and reducing its interference with flotation. This invention simultaneously achieves desliming and dereagent removal, improving flotation water quality and ensuring production targets are met under closed-circuit conditions. This method is simple, effective, and easy to implement industrially, effectively solving the problem of unsatisfactory production targets in closed-circuit rare earth flotation.

[0063] 3. The process provided by this invention dynamically de-recycles the production wastewater, then uses it for closed-circuit flotation of rare earth elements. The concentrate grade REO is ≥58%, and the operating recovery rate is ≥50%, both key indicators meeting the standards. This method can be widely applied to rare earth ore beneficiation production, solving the current difficulty of using wastewater for flotation, ensuring the quality and yield of rare earth concentrates, while reducing water and reagent costs and wastewater discharge, resulting in significant economic and social benefits. Attached Figure Description

[0064] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0065] Figure 1 This is a process flow diagram for improving rare earth flotation parameters through closed-loop decanting in a specific embodiment of the present invention. Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0067] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0068] According to a first aspect of the present invention, a method for closed-circuit decanting and flotation of rare earth elements using recycled water is provided, specifically comprising the following steps:

[0069] S1: Perform the first desliming process on the raw ore slurry to obtain upper layer slime and lower layer slurry;

[0070] Among them, raw ore refers to rare earth raw ore slurry, which is also the tailings after iron beneficiation. In the iron beneficiation process, recycled water is needed for grinding, flotation and other processes. Therefore, the raw ore slurry obtained contains residual fluorite flotation collectors and other reagents in the recycled water.

[0071] S2: Add water glass, collector and frother to the bottom slurry obtained in step S1, and carry out roughing to obtain roughing foam and roughing slurry;

[0072] S3: Collector and frother are added to the slurry after roughing to carry out scavenging to obtain scavenging tailings and scavenging foam;

[0073] S4: Add water glass and collector to the scavenging foam and roughing foam to carry out the first cleaning process and obtain the first middlings and the first cleaned foam.

[0074] S5: Perform a second refinement on the first selected foam to obtain the second medium ore and the second selected foam;

[0075] S6: Perform a second desliming process on the second selected foam to obtain concentrate desliming water and rare earth concentrate.

[0076] S7: The concentrate desliming water obtained in step S6 and the second intermediate ore obtained in step S5 are fed into the raw ore slurry in step S1 to continue rare earth flotation, thus achieving a closed circuit.

[0077] Specifically, the present invention feeds the concentrate desliming water obtained in step S6 into the raw ore slurry in the next experimental step S1 because the rare earth collector contained in the concentrate desliming water can interact with the fatty acid collectors of residual fluorite flotation in the production return water to produce substances that are easy to float. In the first desliming operation, the upper layer of ore slime is manually poured out (laboratory method) or discharged through the thickener overflow (actual production method), thus avoiding the influence of the fatty acid collectors of residual fluorite flotation in the return water on the subsequent rare earth flotation process.

[0078] Furthermore, the present invention feeds the second intermediate ore obtained in step S5 into the raw ore slurry in the next test step S1 because the second intermediate ore has a high rare earth content. The rare earth in the second intermediate ore was not selected in the roughing and first cleaning processes because of its coarse particle size or because it is an intergrowth. Therefore, feeding the second intermediate ore into the raw ore slurry in the next test step S1 can increase the total rare earth metal content in the next test, thereby improving the recovery rate of the operation.

[0079] As an optional embodiment of the present invention, the collector in steps S1, S3 and S4 is a rare earth collector, including KYR-1 type collector or LF8# collector.

[0080] Specifically, the LF8# collector was purchased from Baogang Linfeng Rare Earth Technology Co., Ltd.

[0081] As an optional embodiment of the present invention, the preparation method of the KYR-1 type collector includes the following steps:

[0082] Fatty acid methyl ester and hydroxylamine hydrochloride were heated and mixed to obtain KYR-1 type collector;

[0083] Preferably, the mass ratio of the fatty acid methyl ester to hydroxylamine hydrochloride is (1-3):(1-3), such as 1:1, 1:1.5, 1:2, 1:2.5, 1.5:2, 2:2, 2.5:2, 2.5:2.5, 3:1, 3:1.5, 1:3, 3:2.5, etc.

[0084] Preferably, the heating and mixing temperature is 50-80℃ (e.g., 55℃, 60℃, 65℃, 70℃, 75℃, etc.), and the heating and mixing time is 2-4h (e.g., 2.5h, 3h, 3.5h, etc.).

[0085] Specifically, residual fatty acid reagents from fluorite flotation are adsorbed on the surface of the mineral particles in the raw ore, affecting the rare earth flotation process using recycled water. The rare earth collector contains hydroxamic acid, which has a stronger adsorption force on the rare earth mineral particles in the raw ore. During the competitive adsorption process, the fatty acid reagents, due to their weaker adsorption force on the mineral particle surface, are forced to desorb, causing them to detach from the rare earth mineral particles and float to the surface of the pulp. In the first desliming operation, the upper layer of slime is manually poured out (laboratory method) or discharged through thickener overflow (actual production method) to avoid interfering with the rare earth flotation process using recycled water.

[0086] As an optional embodiment of the present invention, the foaming agent in steps S1, S3 and S4 includes one or more of No. 2 oil (pine oil), H103 or J102, preferably No. 2 oil.

[0087] Specifically, water glass, as a modifier, primarily functions to inhibit the floatability of certain minerals. During flotation, it can suppress the floatability of gangue minerals in rare earth ores, such as pyrite, fluorite, barite, calcite, feldspar, and quartz, thereby increasing the recovery rate of the target mineral.

[0088] The KYR-1 type collector or LF8# collector used in this invention are both rare earth collectors and are hydroxamic acid preparations. They can selectively adsorb onto the surface of the target mineral, thereby enhancing the hydrophobicity of the target mineral surface, making it easier for mineral particles to adhere to the bubbles and float to the surface of the slurry with the bubbles.

[0089] The foaming agents used in this invention, such as No. 2 oil, H103, or J102, are specifically designed for rare earth flotation. Their function is to reduce the surface tension at the water-air interface, promoting the formation of numerous stable microbubbles in the slurry. These bubbles adhere to the hydrophobic mineral particles, helping them float to the slurry surface and form a foam layer, thereby achieving separation from gangue minerals.

[0090] As an optional embodiment of the present invention, the raw ore slurry obtained before the first desliming operation has a slurry concentration of 60-65% (e.g., 61%, 62%, 63%, 64%, etc.) and a temperature of 20-30℃ (e.g., 22℃, 24℃, 26℃, 28℃, etc.).

[0091] As an optional embodiment of the present invention, the raw ore slurry is screened and analyzed, including the following steps:

[0092] Multi-element analysis and particle size analysis were performed on the raw ore slurry to obtain the content ratio of each element in the raw ore and the distribution of minerals of different particle sizes in the raw ore.

[0093] As an optional embodiment of the present invention, step S1 includes the following:

[0094] The raw ore slurry is placed in a container, production return water is added, and the mixture is stirred. After stirring, the mixture is allowed to stand to obtain the upper layer of ore mud and the lower layer of ore slurry.

[0095] Specifically, in the first desliming process, the desliming water from the second medium ore and concentrate obtained in the previous test is added to the raw ore slurry and mixed to simulate the desliming process of the raw ore well. After stirring and settling, the upper layer of ore sludge is poured out or discharged through the overflow of the thickener. The removed residue exists in this part of the upper layer of ore sludge or the overflow. In actual production, the overflow is directly discharged into the tailings.

[0096] The production wastewater refers to the total wastewater from the entire "iron-rare earth-fluorite" beneficiation process.

[0097] The mass-to-volume ratio of raw ore slurry to production recycled water is 1.6 g: 1 mL;

[0098] In one embodiment of the present invention, the stirring is performed using a JJ-1 type electric mechanical stirrer; in actual production, other large-scale stirring equipment can also be used to achieve full mixing of the added production return water and the raw ore slurry, so that the residual fluorite flotation collector and other reagents in the return water can combine with the middlings mud in the raw ore slurry, so as to facilitate the desliming of the raw ore slurry.

[0099] The stirring time is 3 to 5 minutes (e.g., 3.5 minutes, 4 minutes, 4.5 minutes, etc.), and the stirring speed is 150 to 200 rad / min (e.g., 160 rad / min, 170 rad / min, 180 rad / min, 190 rad / min, etc.). After stirring, let it stand for 8 to 12 minutes (e.g., 9 minutes, 10 minutes, 11 minutes, etc.).

[0100] As an optional embodiment of the present invention, step S2, the coarse selection process includes:

[0101] Pour the bottom slurry obtained in step S1 into the flotation cell, and then add water glass, collector and frother in sequence. After an interval of 2 to 3 minutes (e.g. 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes, etc.), start roughing and frothing to obtain roughing froth and roughing slurry.

[0102] The roughing temperature is 60-65℃ (e.g., 61℃, 62℃, 63℃, 64℃, etc.), the pulp concentration of the bottom pulp is 60-65% (e.g., 61%, 62%, 63%, 64%, etc.), and the pH is 8-9.

[0103] The water glass, collector, and foaming agent should be added at intervals of 3-5 minutes (e.g., 3.5 minutes, 4 minutes, 4.5 minutes, etc.).

[0104] The addition amount of water glass is 10,000-15,000 mL / t (e.g., 11,000 mL / t, 12,000 mL / t, 13,000 mL / t, 14,000 mL / t, etc.), the addition amount of collector is 50,000-70,000 mL / t (e.g., 55,000 mL / t, 60,000 mL / t, 65,000 mL / t, etc.), and the addition amount of foaming agent is 100-150 mL / t (e.g., 110 mL / t, 120 mL / t, 130 mL / t, 140 mL / t, etc.).

[0105] The time for roughing and skimming is 2 to 3 minutes (e.g., 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes, etc.).

[0106] In an optional embodiment of the present invention, step S3 includes the following scanning operation:

[0107] Collector and frother are added sequentially to the roughing pulp. After 2-3 minutes (e.g., 2.2 min, 2.4 min, 2.6 min, 2.8 min, etc.), scavenging and frothing are started to obtain scavenging froth and scavenging tailings.

[0108] The scavenging temperature is 60-65℃ (e.g., 61℃, 62℃, 63℃, 64℃, etc.), the pulp concentration after roughing is 50-55% (e.g., 51%, 52%, 53%, 54%, etc.), and the pH is 8-9.

[0109] The time interval between adding the collector and the foaming agent is 1 to 2 minutes (e.g., 1.2 minutes, 1.4 minutes, 1.6 minutes, 1.8 minutes, etc.);

[0110] The amount of collector added is 30,000 to 4,000 mL / t (e.g., 32,000 mL / t, 34,000 mL / t, 36,000 mL / t, 38,000 mL / t, etc.), and the amount of foaming agent added is 50 to 100 mL / t (e.g., 60 mL / t, 70 mL / t, 80 mL / t, 90 mL / t, etc.).

[0111] The time for sweeping and skimming is 2 to 3 minutes (e.g., 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes, etc.).

[0112] Specifically, the purpose of scavenging is to continue to float the rare earth elements in the remaining slurry in the flotation cell after roughing. Most of the gangue minerals that need to be suppressed have already been suppressed in the first roughing step, so water glass does not need to be added in step S3.

[0113] As an optional embodiment of the present invention, step S4, the first selection includes:

[0114] Pour the scavenging froth and roughing froth into the flotation cell, add water glass and collector in sequence, and after 1 to 2 minutes (e.g., 1.2 minutes, 1.4 minutes, 1.6 minutes, 1.8 minutes, etc.), start the first cleaning froth removal to obtain the first middlings and the first cleaned froth.

[0115] The first fine-graining process is carried out at a temperature of 60–65℃ (e.g., 61℃, 62℃, 63℃, 64℃, etc.), and the pulp concentration of the scavenging froth and roughing froth is 50–55% (e.g., 51%, 52%, 53%, 54%, etc.), with a pH of 8–9.

[0116] The main components of the scavenging foam and the roughing foam are rare earth minerals.

[0117] The time interval between adding water glass and the collector is 1 to 2 minutes (e.g., 1.2 minutes, 1.4 minutes, 1.6 minutes, 1.8 minutes, etc.);

[0118] The amount of water glass added is 1000-1200 mL / t (e.g., 1050 mL / t, 1100 mL / t, 1120 mL / t, 1140 mL / t, 1160 mL / t, 1180 mL / t, etc.), and the amount of collector added is 15000-20000 mL / t (e.g., 16000 mL / t, 17000 mL / t, 18000 mL / t, 19000 mL / t, etc.).

[0119] The time for the first selection and scraping is 3 to 4 minutes (e.g., 3.2 minutes, 3.4 minutes, 3.6 minutes, 3.8 minutes, etc.).

[0120] Specifically, foaming agents such as No. 2 oil are helpful for mineral collection but have poor selectivity and tend to collect gangue minerals as well. They are suitable for roughing steps but not for fine selection steps where higher product purity is required. Therefore, no foaming agent is added in step S4.

[0121] As an optional embodiment of the present invention, the scavenging tailings and the first intermediate ore are used as feed for the next step of comprehensive fluorite recovery.

[0122] As an optional embodiment of the present invention, step S5, the second selection includes:

[0123] The first refined froth is poured into the flotation cell for a second refined froth removal process to obtain the second middlings and the second refined froth.

[0124] The second refining temperature is 60-65℃ (e.g., 61℃, 62℃, 63℃, 64℃, etc.), the pulp concentration of the first refining froth is 40-45% (e.g., 41%, 42%, 43%, 44%, etc.), and the pH is 8-9.

[0125] The main component of the first selected foam is rare earth minerals;

[0126] The second fine-scraping time is 2 to 3 minutes (e.g., 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes, etc.).

[0127] As an optional embodiment of the present invention, step S6 includes the second desliming operation:

[0128] Pour the second selected foam into a container, add production return water, stir, and let it stand after stirring to obtain concentrate desliming water and rare earth concentrate.

[0129] The volume ratio of the second selected foam to the production recycled water is 1 mL: 3 mL.

[0130] The stirring refers to stirring using a JJ-1 type electric mechanical stirrer;

[0131] The stirring time is 3 to 5 minutes (e.g., 3.5 minutes, 4 minutes, 4.5 minutes, etc.), and the stirring speed is 150 to 200 rad / min (e.g., 160 rad / min, 170 rad / min, 180 rad / min, 190 rad / min, etc.). After stirring, let it stand for 5 to 10 minutes (e.g., 6 minutes, 7 minutes, 8 minutes, 9 minutes, etc.).

[0132] As an optional embodiment of the present invention, the scavenging tailings and the first intermediate ore are used as feed for the next step of comprehensive fluorite recovery.

[0133] The present invention will now be described in further detail with reference to specific embodiments and comparative examples.

[0134] The preparation method of the KYR-1 collector used in the embodiments and comparative examples of this invention is as follows:

[0135] Fatty acid methyl ester and hydroxylamine hydrochloride were mixed at a mass ratio of 1:1 and reacted at 70°C for 4 hours to obtain KYR-1 type collector.

[0136] Example 1

[0137] 1L of circulating raw ore slurry (i.e., tailings after iron ore beneficiation) was taken from the dilute ore separation bin of Baogang Baoshan Mining Company. The slurry concentration was approximately 65%, and the temperature was approximately 25℃. The raw ore slurry was then screened and analyzed.

[0138] Multi-element analysis and particle size analysis were performed on the raw ore slurry to obtain the content ratio of each element in the raw ore and the distribution of minerals of different particle sizes in the raw ore.

[0139] The results of the element content ratio analysis in the raw ore are shown in Table 2:

[0140] Table 2. Results of multi-element chemical analysis of the raw ore.

[0141] Components REO TFe F P S CaO MgO <![CDATA[K2O]]> content / % 8.40 13.22 6.899 1.56 1.120 22.00 2.55 0.71 Components <![CDATA[Na2O]]> <![CDATA[Al2O3]]> <![CDATA[SiO2]]> <![CDATA[Nb2O5]]> <![CDATA[Sc2O3]]> <![CDATA[TiO2]]> BaO <![CDATA[ThO2]]> content / % 1.25 0.58 17.43 0.16 290.66ppm 0.35 3.28 0.010

[0142] According to Table 2, the mass percentage of rare earth oxides (REO) in the raw ore is 8.4%.

[0143] The distribution of minerals of different grain sizes in the raw ore is shown in Table 3:

[0144] Table 3. Sieve analysis results of minerals of different particle sizes in the raw ore.

[0145] Particle size Yield / % REO / % Distribution rate / % -500 mesh 48.71 10.12 59.18 -400~+500 mesh 9.10 9.82 10.68 -300~+400 mesh 12.67 9.20 14.05 -200~+300 mesh 12.85 6.35 9.84 +200 mesh 16.67 3.11 6.25 total 100.00 8.33 100.00

[0146] As shown in Table 3, the analysis of the raw ore particle size in Table 3 is to ensure that the raw ore particle size is within the range most conducive to recovery. Generally, when carrying out rare earth flotation, the raw ore is required to have a particle size of -200 mesh ≥ 85%. Under this particle size condition, the degree of liberation of rare earth minerals is better, and the flotation index is better under the same conditions. It can be used as a general requirement for the feed of rare earth flotation.

[0147] A method for closed-circuit de-dosing flotation of rare earth elements using recycled water includes:

[0148] S1: Perform the first desliming process on the raw ore slurry to obtain the upper layer slime and the lower layer slurry.

[0149] Place the raw ore slurry in a 5000ml glass beaker, add 1000ml of production return water, and stir for 3 minutes using a JJ-1 electric mechanical stirrer at a speed of 180rad / min. After stirring, let it stand for 10 minutes to obtain the upper layer of ore mud and the lower layer of ore slurry. Pour out the upper layer of ore mud manually.

[0150] S2: Perform roughing on the bottom slurry obtained in step S1 to obtain roughing froth and roughing slurry:

[0151] Pour the bottom slurry obtained in step S1 into a 1L plastic flotation cell for roughing. The roughing temperature is 60℃, the concentration is 65%, and the pH is approximately 8.5. Add 13ml of water glass, wait 3 minutes, then add 60ml of KYR-1 type collector, wait 5 minutes, then add 2 drops of No. 2 oil, wait 2 minutes, and then start roughing froth scraping for 2 minutes to obtain roughing froth and roughing slurry.

[0152] S3: Scavenging is performed on the slurry after roughing to obtain scavenging tailings and scavenging froth.

[0153] Pour the roughing pulp into the flotation cell, add 30ml of KYR-1 collector to the pulp, add 1 drop of No. 2 oil after 1 minute, and start scavenging and skimming after 2 minutes. Skim for 2 minutes and 30 seconds to obtain scavenging froth and scavenging tailings.

[0154] S4: Perform a first-stage refining process on the scavenging foam and roughing foam to obtain the first-stage medium ore and the first-stage refined foam:

[0155] The scavenging froth and roughing froth were combined and poured into a 0.75L plastic flotation cell for the first cleaning process. The cleaning temperature was 60℃, the concentration was 50%, and the pH was approximately 8.5. 1ml of water glass was added, and after a 1-minute interval, 15ml of KYR-1 collector was added. After another 1-minute interval, the first cleaning froth scraping began and lasted for 3 minutes. The first middlings and the first cleaned froth were obtained. The first middlings and the scavenging tailings can be used as feed for the next step of fluorite comprehensive recovery.

[0156] S5: Perform a second refinement on the first selected foam to obtain the second medium-grade ore and the second selected foam:

[0157] The first selected foam is poured into a 0.5L plastic flotation cell for a second selection. The selection temperature is 60℃, the concentration is 40%, and the pH is approximately 8.5. The second selection foam scraping begins and lasts for 2 minutes and 30 seconds. The second middlings and the second selected foam are obtained. All of the second middlings are poured into the raw ore slurry from step S1.

[0158] S6: Perform a second desliming operation in the second fine foam to obtain concentrate desliming water and rare earth concentrate:

[0159] Pour the second batch of selected foam into a 2000ml glass beaker, add 500ml of production return water, and stir for 3 minutes using a JJ-1 electric mechanical stirrer at a speed of 180 rad / min. After stirring, let it stand for 8 minutes to obtain concentrate desliming water and rare earth concentrate with a concentrate grade REO≥58%.

[0160] S7: The concentrate desliming water obtained in step S6 and the second medium ore obtained in step S5 are fed into the raw ore slurry in step S1 to achieve a closed loop.

[0161] Following the closed-loop water return and reagent removal experimental method and conditions described above, four sets of experiments were conducted. The first set of experiments only included steps S1-S6. The concentrate desliming water obtained in step S6 of the first set of experiments and the second intermediate ore obtained in step S5 were fed into the raw ore slurry of the second set of experiments. Then, the concentrate desliming water obtained in step S6 of the second set of experiments and the second intermediate ore obtained in step S5 were fed into the raw ore slurry of the third set of experiments. Finally, the concentrate desliming water obtained in step S6 of the third set of experiments and the second intermediate ore obtained in step S5 were fed into the raw ore slurry of the fourth set of experiments, thus achieving a closed loop.

[0162] The experimental results of the second to fourth groups are shown in Table 4 below:

[0163] Table 4 Closed-circuit stability test data

[0164]

[0165] Comparative Example 1

[0166] The difference between this comparative example and Example 1 is that the concentrate desliming water obtained in step S6 of the first group of experiments and the second middlings obtained in step S5 are fed into step S4 of the second group for further refining; the concentrate desliming water obtained in step S6 of the second group of experiments and the second middlings obtained in step S5 are fed into step S4 of the third group for further refining; and the concentrate desliming water obtained in step S6 of the third group of experiments and the second middlings obtained in step S5 are fed into step S4 of the fourth group for further refining. All other steps and technical parameters are the same as in Example 1. The experimental results are shown in Table 5.

[0167] Table 5. Results of Comparative Example 1

[0168]

[0169] As shown in Table 5, in the first to fourth groups of experiments in Comparative Example 1, the concentrate desliming water obtained in step S6 and the second medium ore obtained in step S5 were fed into step S4 for further refining. The interference of residual reagents in the reflux water was not completely eliminated, which resulted in the rare earth concentrate grade REO and recovery rate indicators not meeting the requirements at the same time.

[0170] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for closed-circuit de-drug flotation of rare earth elements using recycled water, characterized in that, Includes the following steps: S1: Perform the first desliming process on the raw ore slurry to obtain upper layer slime and lower layer slurry; The first desliming process includes: placing the raw ore slurry in a container, adding production return water, stirring, and allowing it to stand after stirring to obtain upper ore slime and lower ore slurry; wherein, the production return water is the total return water of the entire "iron-rare earth-fluorite" beneficiation process; S2: Add water glass, collector and frother to the bottom slurry obtained in step S1, and carry out roughing to obtain roughing foam and roughing slurry; S3: Collector and frother are added to the slurry after roughing to carry out scavenging to obtain scavenging tailings and scavenging foam; S4: Add water glass and collector to the scavenging foam and roughing foam to perform the first cleaning process and obtain the first middlings and the first cleaned foam. S5: Perform a second refinement on the first selected foam to obtain the second medium ore and the second selected foam; S6: Perform a second desliming process on the second selected foam to obtain concentrate desliming water and rare earth concentrate; The second desliming process includes: Pour the second selected foam into a container, add production return water, stir, and let it stand after stirring to obtain concentrate desliming water and rare earth concentrate. S7: The concentrate desliming water obtained in step S6 and the second intermediate ore obtained in step S5 are fed into the raw ore slurry in step S1 to continue rare earth flotation, thus achieving a closed circuit. The collectors in steps S2, S3 and S4 are rare earth collectors, including KYR-1 type collectors or LF8# collectors.

2. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 1, characterized in that, The foaming agent in steps S2 and S3 includes one or more of No. 2 oil, H103, or J102.

3. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 2, characterized in that, The foaming agent in steps S2 and S3 is No. 2 oil.

4. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 1, characterized in that, The preparation method of the KYR-1 type collector includes the following steps: Fatty acid methyl ester and hydroxylamine hydrochloride were heated and mixed to obtain KYR-1 type collector.

5. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 4, characterized in that, The mass ratio of the fatty acid methyl ester to hydroxylamine hydrochloride is (1-3):(1-3).

6. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 4, characterized in that, The heating and mixing temperature is 50-80℃, and the heating and mixing time is 2-4 hours.

7. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 1, characterized in that, The raw ore slurry in step S1 has a slurry concentration of 60-65% and a temperature of 20-30℃; Screening and analysis of raw ore slurry includes the following steps: Multi-element analysis and particle size analysis were performed on the raw ore slurry to obtain the content ratio of each element in the raw ore and the distribution of minerals of different particle sizes in the raw ore.

8. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 1, characterized in that, In step S1, the mass-to-volume ratio of raw ore slurry to production recycled water is 1.6 g: 1 mL; The stirring time is 3 to 5 minutes, and the stirring speed is 150 to 200 rad / min; after stirring, let it stand for 8 to 12 minutes.

9. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 1, characterized in that, In step S2, the coarse selection process includes: Pour the bottom slurry obtained in step S1 into the flotation cell, and then add water glass, collector and frother in sequence. After an interval of 2 to 3 minutes, start roughing and frothing to obtain roughing froth and roughing slurry. The roughing temperature is 60-65℃, the pulp concentration of the bottom pulp is 60-65%, and the pH is 8-9. The water glass, collector, and foaming agent should be added at intervals of 3-5 minutes. The amount of water glass added is 10,000-15,000 mL / t, the amount of collector added is 50,000-70,000 mL / t, and the amount of foaming agent added is 100-150 mL / t. The time for rough selection and foaming is 2-3 minutes.

10. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 1, characterized in that, In step S3, the scanning operation includes: Collector and frother are added sequentially to the roughing pulp. After an interval of 2-3 minutes, scavenging and frothing are started to obtain scavenging foam and scavenging tailings. The scavenging temperature is 60~65℃, the pulp concentration of the pulp after roughing is 50~55%, and the pH is 8~9. The time interval between adding the collector and the foaming agent is 1 to 2 minutes; The amount of collector added is 30,000~4,000 mL / t, and the amount of foaming agent added is 50~100 mL / t; The time for the sweeping and skimming process is 2-3 minutes.

11. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 1, characterized in that, In step S4, the first selection includes: Pour the scavenging foam and roughing foam into the flotation cell, add water glass and collector in sequence, and after an interval of 1 to 2 minutes, start the first cleaning and frothing process to obtain the first middlings and the first cleaned foam. The first fine-graining process is carried out at a temperature of 60-65℃, and the pulp concentration of the scavenging foam and roughing foam is 50-55%, with a pH of 8-9. The time interval between adding water glass and the collector is 1-2 minutes; The amount of water glass added is 1000~1200mL / t, and the amount of collector added is 15000~20000mL / t; The first selection and scraping time is 3-4 minutes.

12. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 1, characterized in that, In step S5, the second selection includes: The first refined froth is poured into the flotation cell for a second refined froth removal process to obtain the second middlings and the second refined froth. The second refining temperature is 60~65℃, the first refining foam has a pulp concentration of 40~45% and a pH of 8~9; The second round of fine-scraping and foaming should take 2-3 minutes.

13. The method for closed-circuit de-drug flotation of rare earth elements using recycled water according to claim 1, characterized in that, In step S6, the volume ratio of the second selected foam to the production return water is 1 mL: 3 mL; The stirring refers to stirring using a JJ-1 type electric mechanical stirrer; The stirring time is 3-5 minutes, and the stirring speed is 150-200 rad / min; after stirring, let it stand for 5-10 minutes.

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