Magnetite-hematite micro-fine refractory iron ore separation method

Abstract

A magnetite-hematite micro-fine refractory iron ore separation method, comprising the specific steps: 1) performing crushing and screening on micro-fine-particle magnetite-hematite mixed raw iron ore and performing grinding and screening on same to obtain an ore grinding product; 2) performing weak magnetic and strong magnetic grading operation on the ore grinding product to obtain magnetic separation concentrate and magnetic separation tailings; 3) performing nanobubble pretreatment on a flotation reagent and then adding the pretreated flotation reagent to the magnetic separation concentrate to obtain the flotation feed mineral slurry; and 4) performing ultrasonic pretreatment on the flotation ore feeding slurry, and then performing reverse flotation closed-loop operation to obtain reverse flotation concentrate and reverse flotation tailings.

Description

A magnetic-red fine refractory iron ore separation method Technical Field

[0001] The invention belongs to the technical field of mineral processing, relates to a separation technology for fine-grained refractory iron ore, and particularly relates to a separation method for magnetic-heterobaric fine-grained refractory iron ore. Background Art

[0002] Iron ore is a relatively important industrial resource for the entire international community and has a huge impact on the national economy. However, with the reduction of iron ore resources and the decline in ore quality, the characteristics of iron ore resources such as "poor, fine and mixed" have gradually emerged. The ore particle size is getting finer and finer, the grinding fineness is gradually increasing, and the difficulty of flotation is constantly increasing. This makes it difficult to adapt to the traditional "crushing-stage grinding-gravity magnetic flotation combined separation" process, and the recovery rate is greatly reduced.

[0003] In recent years, with the increasing maturity of nanobubble technology, its application in mineral flotation has become increasingly common. Its stable foam properties can improve the flotation recovery of fine-grained minerals. For example, Chinese patent application number CN 115041293 A, "A New Method for Enhanced Efficient Recovery of Fine-Grained Refractory Iron Ore by Microbubble Flotation," demonstrates that nanobubble flotation can achieve efficient recovery of fine-grained iron minerals, improving concentrate grade and recovery rate. However, practice has shown that the application of nanobubble technology in flotation also has certain shortcomings. First, the nanobubble effect can negatively impact the flotation of coarse-grained minerals, reducing their recovery rate and grade. When the particle size range in the flotation slurry is large, the overall flotation effect is often poor. Second, nanobubble pretreatment of the flotation agent alone often results in unsatisfactory flotation results. However, nanobubble pretreatment of the slurry with the addition of flotation agents overloads the equipment, significantly increasing equipment wear and tear and making long-term operation difficult.

[0004] Therefore, the development of new fine-grained iron ore sorting methods is of great significance for fully utilizing the global lean iron ore resources, achieving efficient recovery of iron ore, reducing tailings storage pressure, and maintaining high-quality iron ore raw material supply.

[0005] Summary of the Invention

[0006] The existing "crushing-stage grinding-gravity magnetic flotation combined separation" process is limited to purifying iron ore with a particle size range of 200 mesh to 325 mesh, while it is difficult to process iron ore with a particle size less than 325 mesh, the recovery efficiency is extremely low, and the application of nanobubble technology in flotation still has defects and other problems. The present invention provides a fine-grained iron ore separation method based on the combined action of nanobubbles and ultrasound to effectively solve the recovery efficiency of fine-grained refractory iron ore. The purpose is to enhance the dispersion ability of the flotation agent in the ore pulp through the pretreatment of the flotation reagent by nanobubbles and the pretreatment of the flotation feed slurry by ultrasound, improve the flotation ability of fine-grained minerals in the ore pulp and the separation effect of useful minerals and gangue minerals during the flotation process, thereby effectively realizing the recovery and utilization of fine-grained refractory iron ore, improving the flotation recovery rate, and reducing the iron grade in the flotation tailings.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions:

[0008] The chemical composition of the fine-grained magnetic-hematite mixed ore processed by the present invention is as follows by weight: TFe 25%-35%, CaO 0.1%-1.5%, MgO 0.1%-1.5%, SiO2 30%-40%, S 0.01%-0.1%, P 0.01%-0.1%, and the remainder is impurities.

[0009] The iron phase composition of the fine-grained magnetic-hematite mixed ore processed by the present invention is as follows: 25% to 35% hematite, 15% to 30% magnetite, 1% to 3% siderite, 0.1% to 1% pyrite, and the remainder is iron-containing silicate and other impurities.

[0010] Aiming at the above-mentioned fine-grained magnetic-hematite mixed iron ore, the present invention proposes a method for separating magnetic-hematite fine refractory iron ore. The separation process includes crushing, grinding, magnetic separation, flotation dosing, and flotation. In the flotation dosing process, the flotation agent is pretreated with nanobubbles. In the flotation process, the flotation feed slurry is pretreated with ultrasonic waves. The specific steps include:

[0011] 1) Grinding: The fine-grained magnetic-hematite mixed ore is crushed, screened, ground and screened to obtain the grinding product.

[0012] The fineness of the crushed product after the crushing-screening closed-circuit operation is ≤12mm, and the part >12mm is returned to the crusher for further crushing; after the crushed product undergoes the grinding-screening closed-circuit operation, the grinding product with a particle size of ≤400 mesh, accounting for more than 85%, is obtained.

[0013] 2) Magnetic separation: The ground ore products are subjected to weak magnetic and strong magnetic classification operations to obtain magnetic concentrate and magnetic tailings.

[0014] Among them, the concentrate obtained after weak magnetic treatment is classified, and the concentrate with a particle size of less than 325 mesh enters the flotation pretreatment, and the concentrate with a particle size of ≥325 mesh is returned to the ball mill for regrinding; the tailings obtained after weak magnetic treatment are concentrated, the upper clear liquid enters the clarifier, and the precipitated slurry enters the strong magnetic separation operation. The concentrate produced by the strong magnetic separation operation is merged with the weak magnetic separation concentrate and enters the classification operation together to obtain the magnetic separation concentrate; the tailings from the strong magnetic separation operation are concentrated to obtain the magnetic separation tailings.

[0015] After the grinding products are subjected to weak magnetic and strong magnetic classification operations, the obtained magnetic separation concentrate contains 40% to 50% TFe by weight and the iron recovery rate is 70% to 90%.

[0016] 3) Flotation dosing: First, the flotation reagent is pretreated with nanobubbles, and the mixed flotation reagent is cavitated to form nanobubbles in the flotation reagent. The pretreated flotation reagent is added to the magnetic separation concentrate to obtain the flotation feed slurry.

[0017] The flotation reagent is mixed as follows: first, starch as an inhibitor is added to a mixing barrel and stirred for 2 to 3 minutes. The amount of starch added is 200 to 500 g / t of magnetic concentrate; then, CaO as a pH adjuster is added and stirred for 2 to 3 minutes. The amount of CaO added is 30 to 80 g / t of magnetic concentrate; finally, sodium oleate as a collector is added and stirred for 2 to 3 minutes. The amount of sodium oleate added is 100 to 150 g / t of magnetic concentrate.

[0018] Nanobubble pretreatment uses a Venturi tube for cavitation to form nanobubbles in the flotation reagent. The fluid velocity in the cavitation tube is greater than 12.5m / s, and the cavitation time is greater than 5min. The flotation reagent pretreated with nanobubbles is mixed with the magnetic separation concentrate to form a flotation feed slurry.

[0019] 4) Flotation: The flotation feed slurry is ultrasonically pretreated, and then reverse flotation closed-circuit operation is carried out to obtain reverse flotation concentrate and reverse flotation tailings.

[0020] The ultrasonic equipment is placed in the flotation feed slurry, and the flotation feed slurry is pretreated by ultrasonic waves. The ultrasonic frequency is between 60 and 120 kHz, and the ultrasonic time is 15 to 30 minutes.

[0021] After ultrasonic pretreatment, the flotation feed pulp is subjected to reverse flotation closed-circuit operation to obtain reverse flotation concentrate and reverse flotation tailings. The reverse flotation closed-circuit operation is preferably a one-roughing, one-fine, three-sweeping operation.

[0022] The flotation feed slurry enters the flotation cell and undergoes reverse flotation roughing. The concentrate from the reverse flotation roughing process enters the reverse flotation cleaning process, and the tailings from the reverse flotation roughing process enter the reverse flotation scavenging process. When the concentrate enters the cleaning process, water is added to the reverse flotation roughing concentrate to prepare a reverse flotation roughing concentrate slurry with a weight concentration of 30% to 40%. At the same time, sodium oleate, a collector, is added and stirred for 2 to 3 minutes. The amount of sodium oleate added is 20 to 50 g / t of reverse flotation roughing concentrate slurry.

[0023] When the reverse flotation scavenging is carried out once, the concentrate obtained from the first reverse flotation scavenging is returned to the flotation slurry and reverse flotation roughing is carried out again; when the reverse flotation roughing tailings are subjected to the second reverse flotation scavenging, the concentrate obtained from the second reverse flotation scavenging is mixed with the reverse flotation roughing tailings and the first reverse flotation scavenging is carried out together; when the reverse flotation roughing tailings are subjected to the third reverse flotation scavenging, the concentrate obtained from the third reverse flotation scavenging is mixed with the reverse flotation roughing tailings and the second reverse flotation scavenging is carried out together.

[0024] By adopting the above method, the reverse flotation concentrate obtained contains TFe of 65.5% to 68% by weight, and the iron recovery rate is 70% to 90%.

[0025] Compared with the existing technology, the beneficial effects of the present invention are:

[0026] 1. The present invention adopts the combined action of nanobubbles and ultrasonic waves to separate magnetic-red fine refractory iron ore. Compared with the conventional stage grinding, coarse and fine separation, magnetic separation-anion reverse flotation process, the ore particle size range is wider, especially for iron ore with a particle size of less than 325 mesh, it can still be effectively processed.

[0027] 2. The present invention adopts the combined action of nanobubbles and ultrasound to separate magnetic-red fine refractory iron ore. Compared with the conventional stage grinding, coarse and fine separation, magnetic separation-anion reverse flotation process, the present invention adds a nanobubble and ultrasonic combined pretreatment process before flotation. It can better prevent the fine-grained minerals from becoming slime and adhering to the surface of large-grained minerals during the flotation process, resulting in poor concentrate recovery and high iron grade in tailings, and can also reduce the amount of reagents used.

[0028] 3. Compared to a single nanobubble pretreatment process, the present invention's combined nanobubble and ultrasonic separation method for separating fine, refractory magnetic-hematite iron ore effectively improves the emulsification and dispersion of flotation reagents, ensuring more uniform attachment of the flotation reagent to the mineral surface. It also reduces the impact strength of the nanobubble generator, minimizing equipment loss. The combined effect of ultrasonic waves reduces the adhesion of fine particles to the surface of useful minerals, preventing surface clogging. This further enhances selective dissolution of the mineral surface, positively impacting the flotation of coarse-grained minerals and, consequently, the separation of useful minerals from gangue minerals.

[0029] 4. In the method of separating magnetic-hematite fine refractory iron ore by the combined action of nanobubbles and ultrasound adopted in the present invention, when the ultrasonic frequency is between 60kHz and 120kHz and the ultrasonic time is between 15min and 30min, it will not cause strong turbulence in the ore pulp and affect the action of nanobubbles. Instead, it can enhance the dispersion of nanobubbles in the ore pulp and increase the collision probability between mineral particles and nanobubbles, thereby achieving a synergistic effect between ultrasonic technology and nanobubble flotation.

[0030] 5. The present invention provides a resource recovery process for the development and utilization of similar complex and difficult-to-select lean iron ores, which can effectively improve the recovery rate of fine particles and has important industrial significance for the effective utilization of global fine iron ore resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is a process flow chart of the present invention. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only for illustration and are not intended to limit the present invention.

[0033] The magnetic-hematite mixed iron ore used in the embodiment of the present invention is a mineral produced in Anshan, Liaoning, China. The ore is mined from a mining field and crushed by a jaw crusher.

[0034] In the embodiment of the present invention, the magnetic separator selected for weak magnetic operation is a drum magnetic separator, and the magnetic separator selected for strong magnetic operation is a Slon vertical ring high gradient magnetic separator.

[0035] The ball mill used in the embodiment of the present invention is an XMCQ type porcelain-lined ball mill, and the equipment used for reverse flotation is an XFLB type micro closed-circuit continuous flotation machine.

[0036] The crusher used in the embodiment of the present invention is a laboratory-grade jaw crusher.

[0037] The nano bubble generating device used in the embodiment of the present invention is a Venturi tube type circulating cavitation device.

[0038] The ultrasonic generating device used in the embodiment of the present invention is a 60L multi-frequency ultrasonic cleaner.

[0039] The inhibitor starch, pH regulator CaO, and collector sodium oleate used in the examples of the present invention were all of analytical grade.

[0040] Example 1:

[0041] In this example, mixed magnetic and hematite ore from Anshan, Liaoning, China was selected and the process flow shown in Figure 1 was used. After closed-circuit crushing and screening, material with a particle size of ≤12 mm was obtained. Ore with a particle size greater than 12 mm was returned to the crusher for further crushing. The chemical composition of the crushed material, by weight, was 30.8% TFe, 0.59% CaO, 0.23% MgO, 35.3% SiO2, 0.018% S, 0.035% P, with the remainder being impurities.

[0042] The crushed products are subjected to a closed-circuit grinding and screening process of semi-autogenous grinding and ball milling to obtain grinding products with a mesh size of ≤400, accounting for 86%.

[0043] The grinding products are subjected to weak magnetic and strong magnetic classification operations to obtain magnetic concentrate and magnetic tailings. Among them, the concentrate obtained after weak magnetic treatment is classified, and those with less than 325 mesh enter the flotation pretreatment, while those with ≥325 mesh are returned to the ball mill for regrinding. The tailings obtained after weak magnetic treatment are concentrated, and the supernatant enters the clarifier, and the precipitated slurry enters the strong magnetic separation operation. The concentrate produced by the strong magnetic separation operation is combined with the weak magnetic separation concentrate and enters the classification operation together, which is the magnetic separation concentrate. The tailings from the strong magnetic separation operation are concentrated to obtain magnetic separation tailings.

[0044] The magnetic separation concentrate obtained by the above method contains 43.8% TFe by weight, with an iron recovery rate of 88.3% and the remainder being impurities.

[0045] The final iron concentrate TFe grade and TFe recovery rate under five different pretreatment conditions were compared.

[0046] (1) Nanobubble and ultrasonic combined pretreatment, ultrasonic frequency 75 kHz, ultrasonic time 16 min.

[0047] Before pre-treating the flotation agent with nanobubbles, starch as an inhibitor was added to the mixing barrel and stirred for 3 minutes. The amount of starch added was 300g / t of magnetic concentrate. Then, CaO as a pH adjuster was added and stirred for 3 minutes. The amount of CaO added was 40g / t of magnetic concentrate. Finally, sodium oleate as a collector was added and stirred for 3 minutes. The amount of sodium oleate added was 120g / t of magnetic concentrate.

[0048] The flotation reagent is then passed through a Venturi tube for cavitation, forming nanobubbles within the flotation reagent, achieving nanobubble pretreatment of the slurry. The cavitated slurry serves as the flotation feed slurry. The fluid velocity in the cavitation tube is 13 m / s, and the cavitation time is 6 minutes.

[0049] The ultrasonic equipment is placed in the flotation feed slurry, and the flotation feed slurry is pretreated by ultrasonic waves. The ultrasonic frequency is 75kHz and the ultrasonic time is 16min.

[0050] After ultrasonic treatment, the flotation feed pulp enters the flotation cell and undergoes reverse flotation roughing. The concentrate from the reverse flotation roughing enters the cleaning process, and the tailings from the reverse flotation roughing enter the scavenging process. When the concentrate undergoes reverse flotation cleaning, water is added to the reverse flotation roughing concentrate to prepare a reverse flotation roughing concentrate pulp with a weight concentration of 35%. Sodium oleate, a collector, is added and stirred for 3 minutes. The amount of sodium oleate added is 20g / t of reverse flotation roughing concentrate pulp. When the reverse flotation rougher tailings are subjected to one reverse flotation scavenging, the concentrate obtained from the first reverse flotation scavenging is returned to the flotation slurry and reverse flotation rougher is subjected to another reverse flotation rougher; when the reverse flotation rougher tailings are subjected to two reverse flotation scavengings, the concentrate obtained from the second reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the first reverse flotation scavenging is carried out together; when the reverse flotation rougher tailings are subjected to three reverse flotation scavengings, the concentrate obtained from the third reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the second reverse flotation scavenging is carried out together.

[0051] The composition of the reverse flotation concentrate of the magnetic-hematite mixed iron ore obtained by the above method is that the TFe content is 66.5% by weight, the iron recovery rate is 79.4%, and the balance is impurities.

[0052] (2) Single nanobubble pretreatment

[0053] Before pre-treating the flotation agent with nanobubbles, starch as an inhibitor was added to the mixing barrel and stirred for 3 minutes. The amount of starch added was 300g / t of magnetic concentrate. Then, CaO as a pH adjuster was added and stirred for 3 minutes. The amount of CaO added was 40g / t of magnetic concentrate. Finally, sodium oleate as a collector was added and stirred for 3 minutes. The amount of sodium oleate added was 120g / t of magnetic concentrate.

[0054] The flotation reagent is then passed through a Venturi tube for cavitation, forming nanobubbles within the flotation reagent, achieving nanobubble pretreatment of the slurry. The cavitated slurry serves as the flotation feed slurry. The fluid velocity in the cavitation tube is 13 m / s, and the cavitation time is 6 minutes.

[0055] After nanobubble pretreatment, the flotation feed pulp is fed directly into the flotation cell without ultrasonic treatment. The reverse flotation roughing process begins, with the concentrate entering the cleaning process and the tailings entering the scavenging process. For reverse flotation cleaning, the roughing concentrate is watered to a 35% by weight concentration. Sodium oleate, a collector, is then added and stirred for 3 minutes. The amount of sodium oleate added is 20g / t of the roughing concentrate pulp. When the reverse flotation rougher tailings are subjected to one reverse flotation scavenging, the concentrate obtained from the first reverse flotation scavenging is returned to the flotation slurry and reverse flotation rougher is subjected to another reverse flotation rougher; when the reverse flotation rougher tailings are subjected to two reverse flotation scavengings, the concentrate obtained from the second reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the first reverse flotation scavenging is carried out together; when the reverse flotation rougher tailings are subjected to three reverse flotation scavengings, the concentrate obtained from the third reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the second reverse flotation scavenging is carried out together.

[0056] The composition of the reverse flotation concentrate of the mixed magnetic-hematite ore obtained by the above method was 60.3% TFe by weight, with an iron recovery rate of 66.8%, and the remainder being impurities. The comparative example used nanobubble pretreatment alone for the slurry, resulting in a lower iron recovery rate.

[0057] (3) No pre-processing

[0058] Add inhibitor starch to the mixing barrel and stir for 3 minutes. The amount of starch added is 300g / t magnetic concentrate. Then add pH regulator CaO and stir for 3 minutes. The amount of CaO added is 40g / t magnetic concentrate. Finally, add collector sodium oleate and stir for 3 minutes. The amount of sodium oleate added is 120g / t magnetic concentrate.

[0059] The stirred pulp is directly fed into the flotation tank for reverse flotation roughing. The concentrate from the reverse flotation roughing process enters the cleaning process, and the tailings from the reverse flotation roughing process enters the scavenging process. When the concentrate undergoes reverse flotation cleaning, water is added to the reverse flotation roughing concentrate to create a 35% by weight reverse flotation roughing concentrate slurry. Sodium oleate, a collector, is added and stirred for 3 minutes. The amount of sodium oleate added is 20g / t of reverse flotation roughing concentrate slurry. When the reverse flotation rougher tailings are subjected to one reverse flotation scavenging, the concentrate obtained from the first reverse flotation scavenging is returned to the flotation slurry and reverse flotation rougher is subjected to another reverse flotation rougher; when the reverse flotation rougher tailings are subjected to two reverse flotation scavengings, the concentrate obtained from the second reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the first reverse flotation scavenging is carried out together; when the reverse flotation rougher tailings are subjected to three reverse flotation scavengings, the concentrate obtained from the third reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the second reverse flotation scavenging is carried out together.

[0060] The composition of the reverse flotation concentrate of the mixed magnetic-hematite ore obtained by the above method was 60.1% TFe by weight, with an iron recovery rate of 60.5%, and the remainder being impurities. This comparative example was performed without any pretreatment conditions, and the iron recovery rate was lower in this case.

[0061] (4) Nanobubble and ultrasonic combined pretreatment, ultrasonic frequency 20 kHz, ultrasonic time 10 min.

[0062] Before pre-treating the flotation agent with nanobubbles, starch as an inhibitor was added to the mixing barrel and stirred for 3 minutes. The amount of starch added was 300g / t of magnetic concentrate. Then, CaO as a pH adjuster was added and stirred for 3 minutes. The amount of CaO added was 40g / t of magnetic concentrate. Finally, sodium oleate as a collector was added and stirred for 3 minutes. The amount of sodium oleate added was 120g / t of magnetic concentrate.

[0063] The flotation reagent is then passed through a Venturi tube for cavitation, forming nanobubbles within the flotation reagent, achieving nanobubble pretreatment of the slurry. The cavitated slurry serves as the flotation feed slurry. The fluid velocity in the cavitation tube is 13 m / s, and the cavitation time is 6 minutes.

[0064] The ultrasonic equipment is placed in the flotation feed slurry, and the flotation feed slurry is pretreated by ultrasonic waves. The ultrasonic frequency is 20kHz and the ultrasonic time is 10min.

[0065] After ultrasonic treatment, the flotation feed pulp enters the flotation cell and undergoes reverse flotation roughing. The concentrate from the reverse flotation roughing enters the cleaning process, and the tailings from the reverse flotation roughing enter the scavenging process. When the concentrate undergoes reverse flotation cleaning, water is added to the reverse flotation roughing concentrate to prepare a reverse flotation roughing concentrate pulp with a weight concentration of 35%. Sodium oleate, a collector, is added and stirred for 3 minutes. The amount of sodium oleate added is 20g / t of reverse flotation roughing concentrate pulp. When the reverse flotation rougher tailings are subjected to one reverse flotation scavenging, the concentrate obtained from the first reverse flotation scavenging is returned to the flotation slurry and reverse flotation rougher is subjected to another reverse flotation rougher; when the reverse flotation rougher tailings are subjected to two reverse flotation scavengings, the concentrate obtained from the second reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the first reverse flotation scavenging is carried out together; when the reverse flotation rougher tailings are subjected to three reverse flotation scavengings, the concentrate obtained from the third reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the second reverse flotation scavenging is carried out together.

[0066] The composition of the reverse flotation concentrate of the magnetic-hematite mixed iron ore obtained by the above method is that the TFe content is 61.2% by weight, the iron recovery rate is 69.5%, and the balance is impurities.

[0067] (5) Nanobubble and ultrasonic combined pretreatment, ultrasonic frequency 150 kHz, ultrasonic time 40 min.

[0068] Before pre-treating the flotation agent with nanobubbles, starch as an inhibitor was added to the mixing barrel and stirred for 3 minutes. The amount of starch added was 300g / t of magnetic concentrate. Then, CaO as a pH adjuster was added and stirred for 3 minutes. The amount of CaO added was 40g / t of magnetic concentrate. Finally, sodium oleate as a collector was added and stirred for 3 minutes. The amount of sodium oleate added was 120g / t of magnetic concentrate.

[0069] The flotation reagent is then passed through a Venturi tube for cavitation, forming nanobubbles within the flotation reagent, achieving nanobubble pretreatment of the slurry. The cavitated slurry serves as the flotation feed slurry. The fluid velocity in the cavitation tube is 13 m / s, and the cavitation time is 6 minutes.

[0070] The ultrasonic equipment is placed in the flotation feed slurry, and the flotation feed slurry is pretreated by ultrasonic waves. The ultrasonic frequency is 150kHz and the ultrasonic time is 40min.

[0071] After ultrasonic treatment, the flotation feed pulp enters the flotation cell and undergoes reverse flotation roughing. The concentrate from the reverse flotation roughing enters the cleaning process, and the tailings from the reverse flotation roughing enter the scavenging process. When the concentrate undergoes reverse flotation cleaning, water is added to the reverse flotation roughing concentrate to prepare a reverse flotation roughing concentrate pulp with a weight concentration of 35%. Sodium oleate, a collector, is added and stirred for 3 minutes. The amount of sodium oleate added is 20g / t of reverse flotation roughing concentrate pulp. When the reverse flotation rougher tailings are subjected to one reverse flotation scavenging, the concentrate obtained from the first reverse flotation scavenging is returned to the flotation slurry and reverse flotation rougher is subjected to another reverse flotation rougher; when the reverse flotation rougher tailings are subjected to two reverse flotation scavengings, the concentrate obtained from the second reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the first reverse flotation scavenging is carried out together; when the reverse flotation rougher tailings are subjected to three reverse flotation scavengings, the concentrate obtained from the third reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the second reverse flotation scavenging is carried out together.

[0072] The composition of the reverse flotation concentrate of the magnetic-hematite mixed iron ore obtained by the above method is that the TFe content is 62.7% by weight, the iron recovery rate is 69.4%, and the balance is impurities.

[0073] A comparative analysis of the flotation concentrate indicators under five different conditions in Table 1 shows that when the ultrasonic frequency is between 60 and 120 kHz and the ultrasonic time is between 15 and 30 minutes, the combined pretreatment of nanobubbles and ultrasound can increase the TFe grade of the flotation concentrate by more than 5% and the TFe recovery rate of the flotation concentrate by more than 12% compared with other pretreatment conditions, which has a significant effect on improving the separation efficiency of fine-grained lean iron ore.

[0074] Table 1 Comparative analysis of flotation concentrate indicators under five different pretreatment conditions

[0075] Example 2:

[0076] In this example, mixed magnetic and hematite iron ore from Anshan, Liaoning Province, China was selected and the process flow shown in Figure 1 was used. After closed-circuit crushing and screening, material with a particle size of ≤12 mm was obtained. Ore with a particle size greater than 12 mm was returned to the crusher for further crushing. The chemical composition of the crushed material, by weight, was 31.5% TFe, 0.35% CaO, 0.85% MgO, 37.2% SiO2, 0.016% S, 0.032% P, with the remainder being impurities.

[0077] The crushed products are subjected to a closed-circuit grinding and screening process of semi-autogenous grinding and ball milling to obtain grinding products with a mesh size of ≤400, accounting for 89%.

[0078] The grinding products are subjected to weak magnetic and strong magnetic classification operations to obtain magnetic concentrate and magnetic tailings. Among them, the concentrate obtained after weak magnetic treatment is classified, and those with less than 325 mesh enter the flotation pretreatment, while those with ≥325 mesh are returned to the ball mill for regrinding. The tailings obtained after weak magnetic treatment are concentrated, and the supernatant enters the clarifier, and the precipitated slurry enters the strong magnetic separation operation. The concentrate produced by the strong magnetic separation operation is combined with the weak magnetic separation concentrate and enters the classification operation together, which is the magnetic separation concentrate. The tailings from the strong magnetic separation operation are concentrated to obtain magnetic separation tailings.

[0079] The magnetic separation concentrate obtained by the above method contains 42.6% TFe by weight, with an iron recovery rate of 87.5% and the remainder being impurities.

[0080] Before pre-treating the flotation reagent with nanobubbles, starch inhibitor was added to the mixing barrel and stirred for 2 minutes. The amount of starch added was 250g / t of magnetic concentrate. Then, CaO pH regulator was added and stirred for 2 minutes. The amount of CaO added was 60g / t of magnetic concentrate. Finally, sodium oleate collector was added and stirred for 2 minutes. The amount of sodium oleate added was 140g / t of magnetic concentrate.

[0081] The flotation reagent is then passed through a Venturi tube for cavitation, forming nanobubbles within the flotation reagent, achieving nanobubble pretreatment of the slurry. The cavitated slurry serves as the flotation feed slurry. The fluid velocity in the cavitation tube is 15 m / s, and the cavitation time is 8 minutes.

[0082] Ultrasonic equipment is introduced into the flotation feed pulp to pretreat the flotation feed pulp using ultrasonic waves. The ultrasonic frequency is 90 kHz and the ultrasonic time is 18 minutes.

[0083] The flotation feed slurry, which has undergone ultrasonic pretreatment, is fed into the flotation cell for reverse flotation roughing. The concentrate from the reverse flotation roughing process enters the cleaning process, and the tailings from the reverse flotation roughing process enters the scavenging process. When the concentrate undergoes reverse flotation cleaning, water is added to the reverse flotation roughing concentrate to create a 40% by weight reverse flotation roughing concentrate slurry. Sodium oleate, a collector, is then added and stirred for 2 minutes. The amount of sodium oleate added is 30g / t of reverse flotation roughing concentrate slurry. When the reverse flotation rougher tailings are subjected to one reverse flotation scavenging, the concentrate obtained from the first reverse flotation scavenging is returned to the flotation slurry and reverse flotation rougher is subjected to another reverse flotation rougher; when the reverse flotation rougher tailings are subjected to two reverse flotation scavengings, the concentrate obtained from the second reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the first reverse flotation scavenging is carried out together; when the reverse flotation rougher tailings are subjected to three reverse flotation scavengings, the concentrate obtained from the third reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the second reverse flotation scavenging is carried out together.

[0084] The composition of the reverse flotation concentrate of the magnetic-hematite mixed iron ore obtained by the above method is that the TFe content is 66.9% by weight, the iron recovery rate is 81%, and the balance is impurities.

[0085] Example 3:

[0086] In this example, mixed magnetic and hematite ore from Anshan, Liaoning, China was selected and the process flow shown in Figure 1 was used. After closed-circuit crushing and screening, material with a particle size of ≤12 mm was obtained. Ore with a particle size greater than 12 mm was returned to the crusher for further crushing. The chemical composition of the crushed material, by weight, was 28.9% TFe, 0.85% CaO, 0.19% MgO, 37.8% SiO2, 0.013% S, 0.028% P, with the remainder being impurities.

[0087] The crushed products are subjected to a closed-circuit grinding and screening process of semi-autogenous grinding and ball milling to obtain grinding products with a mesh size of ≤400, accounting for 86%.

[0088] The grinding products are subjected to weak magnetic and strong magnetic classification operations to obtain magnetic concentrate and magnetic tailings. Among them, the concentrate obtained after weak magnetic treatment is classified, and those with less than 325 mesh enter the flotation pretreatment, while those with ≥325 mesh are returned to the ball mill for regrinding. The tailings obtained after weak magnetic treatment are concentrated, and the supernatant enters the clarifier, and the precipitated slurry enters the strong magnetic separation operation. The concentrate produced by the strong magnetic separation operation is combined with the weak magnetic separation concentrate and enters the classification operation together, which is the magnetic separation concentrate. The tailings from the strong magnetic separation operation are concentrated to obtain magnetic separation tailings.

[0089] The magnetic separation concentrate obtained by the above method contains 41.3% TFe by weight, with an iron recovery rate of 86.6% and the remainder being impurities.

[0090] Before pre-treating the flotation reagent with nanobubbles, starch inhibitor was added to the mixing barrel and stirred for 2.5 minutes. The amount of starch added was 500g / t of magnetic concentrate. Then, CaO pH regulator was added and stirred for 2.5 minutes. The amount of CaO added was 60g / t of magnetic concentrate. Finally, sodium oleate collector was added and stirred for 2.5 minutes. The amount of sodium oleate added was 100g / t of magnetic concentrate.

[0091] The flotation reagent is then passed through a Venturi tube for cavitation, forming nanobubbles within the flotation reagent, achieving nanobubble pretreatment of the slurry. The cavitated slurry serves as the flotation feed slurry. The fluid velocity in the cavitation tube is 16 m / s, and the cavitation time is 10 minutes.

[0092] Ultrasonic equipment is introduced into the flotation feed pulp to pretreat the flotation feed pulp using ultrasonic waves. The ultrasonic frequency is 100 kHz and the ultrasonic time is 20 minutes.

[0093] The flotation feed slurry, which has undergone ultrasonic pretreatment, is fed into the flotation cell for reverse flotation roughing. The concentrate from the reverse flotation roughing process enters the cleaning process, and the tailings from the reverse flotation roughing process enters the scavenging process. During reverse flotation cleaning, the reverse flotation roughing concentrate is watered to a 30% by weight reverse flotation roughing concentrate slurry. Sodium oleate, a collector, is then added and stirred for 2.5 minutes. The amount of sodium oleate added is 40g / t of reverse flotation roughing concentrate slurry. When the reverse flotation rougher tailings are subjected to one reverse flotation scavenging, the concentrate obtained from the first reverse flotation scavenging is returned to the flotation slurry and reverse flotation rougher is subjected to another reverse flotation rougher; when the reverse flotation rougher tailings are subjected to two reverse flotation scavengings, the concentrate obtained from the second reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the first reverse flotation scavenging is carried out together; when the reverse flotation rougher tailings are subjected to three reverse flotation scavengings, the concentrate obtained from the third reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the second reverse flotation scavenging is carried out together.

[0094] The composition of the reverse flotation concentrate of the magnetic-hematite mixed iron ore obtained by the above method is that the TFe content is 67.2% by weight, the iron recovery rate is 80.5%, and the balance is impurities.

[0095] Example 4:

[0096] In this example, mixed magnetic and hematite iron ore from Anshan, Liaoning Province, China was selected. After closed-circuit crushing and screening, material with a particle size of ≤12 mm was obtained. Ore with a particle size greater than 12 mm was returned to the crusher for further crushing. The chemical composition of the crushed material, by weight, was 30.8% TFe, 0.59% CaO, 0.23% MgO, 35.3% SiO2, 0.018% S, 0.035% P, and the remainder being impurities.

[0097] The crushed products are subjected to a closed-circuit grinding and screening process of semi-autogenous grinding and ball milling to obtain grinding products with a mesh size of ≤400, accounting for 86%.

[0098] The grinding products are subjected to weak magnetic and strong magnetic classification operations to obtain magnetic concentrate and magnetic tailings. Among them, the concentrate obtained after weak magnetic treatment is classified, and those with less than 325 mesh enter the flotation pretreatment, while those with ≥325 mesh are returned to the ball mill for regrinding. The tailings obtained after weak magnetic treatment are concentrated, and the supernatant enters the clarifier, and the precipitated slurry enters the strong magnetic separation operation. The concentrate produced by the strong magnetic separation operation is combined with the weak magnetic separation concentrate and enters the classification operation together, which is the magnetic separation concentrate. The tailings from the strong magnetic separation operation are concentrated to obtain magnetic separation tailings.

[0099] The magnetic separation concentrate obtained by the above method contains 43.8% TFe by weight, with an iron recovery rate of 88.3% and the remainder being impurities.

[0100] Before pre-treating the flotation agent with nanobubbles, starch as an inhibitor was added to the mixing barrel and stirred for 3 minutes. The amount of starch added was 300g / t of magnetic concentrate. Then, CaO as a pH adjuster was added and stirred for 3 minutes. The amount of CaO added was 40g / t of magnetic concentrate. Finally, sodium oleate as a collector was added and stirred for 3 minutes. The amount of sodium oleate added was 150g / t of magnetic concentrate.

[0101] The flotation reagent is then passed through a Venturi tube for cavitation, forming nanobubbles within the flotation reagent, achieving nanobubble pretreatment of the slurry. The cavitated slurry serves as the flotation feed slurry. The fluid velocity in the cavitation tube is 13 m / s, and the cavitation time is 6 minutes.

[0102] Ultrasonic equipment is introduced into the flotation feed pulp to pretreat the flotation feed pulp using ultrasonic waves. The ultrasonic frequency is 75 kHz and the ultrasonic time is 16 minutes.

[0103] The flotation feed slurry, which has undergone ultrasonic pretreatment, is fed into the flotation cell for reverse flotation roughing. The concentrate from the reverse flotation roughing process enters the cleaning process, and the tailings from the reverse flotation roughing process enters the scavenging process. During reverse flotation cleaning, the reverse flotation roughing concentrate is watered to a 35% by weight reverse flotation roughing concentrate slurry. Sodium oleate, a collector, is then added and stirred for 3 minutes. The amount of sodium oleate added is 20g / t of reverse flotation roughing concentrate slurry. When the reverse flotation rougher tailings are subjected to one reverse flotation scavenging, the concentrate obtained from the first reverse flotation scavenging is returned to the flotation slurry and reverse flotation rougher is subjected to another reverse flotation rougher; when the reverse flotation rougher tailings are subjected to two reverse flotation scavengings, the concentrate obtained from the second reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the first reverse flotation scavenging is carried out together; when the reverse flotation rougher tailings are subjected to three reverse flotation scavengings, the concentrate obtained from the third reverse flotation scavenging is mixed with the reverse flotation rougher tailings and the second reverse flotation scavenging is carried out together.

[0104] The composition of the reverse flotation concentrate of the magnetic-hematite mixed iron ore obtained by the above method is that the TFe content is 66.2% by weight, the iron recovery rate is 85.5%, and the balance is impurities.

Claims

1. A magnetic-red fine refractory iron ore separation method, comprising crushing, grinding, magnetic separation, flotation dosing, and flotation; characterized in that: The flotation reagent is pretreated with nanobubbles during flotation dosing; the flotation feed pulp is pretreated with ultrasonic waves during flotation. The specific steps include: 1) Grinding: crushing, screening, grinding and screening the fine-grained magnetic-hematite mixed ore to obtain the grinding product; 2) Magnetic separation: The grinding products are subjected to weak magnetic and strong magnetic classification operations to obtain magnetic concentrate and magnetic tailings; 3) Flotation dosing: First, the flotation reagent is pretreated with nanobubbles, the mixed flotation reagent is cavitated to form nanobubbles in the flotation reagent, and the pretreated flotation reagent is added to the magnetic separation concentrate to obtain the flotation feed slurry; 4) Flotation: The flotation feed slurry is ultrasonically pretreated, and then reverse flotation closed-circuit operation is carried out to obtain reverse flotation concentrate and reverse flotation tailings.

2. A magnetic-red fine refractory iron ore separation method according to claim 1, characterized in that: The nanobubble pretreatment adopts a venturi tube to perform cavitation to form nanobubbles in the flotation reagent. The fluid velocity in the venturi tube is greater than 12.5 m / s, and the cavitation time is greater than 5 min.

3. A magnetic-red fine refractory iron ore separation method according to claim 1, characterized in that: The ultrasonic pretreatment has an ultrasonic frequency of 60kHz≤120kHz and an ultrasonic time of 15min≤30min.

4. A magnetic-red fine refractory iron ore separation method according to claim 1, characterized in that: The flotation reagents in the above step 3) are mixed as follows: first, starch is added to a stirring barrel and stirred for 2 to 3 minutes, the amount of starch added is 200 to 500 g / t of magnetic concentrate; then, CaO is added and stirred for 2 to 3 minutes, the amount of CaO added is 30 to 80 g / t of magnetic concentrate; finally, sodium oleate is added and stirred for 2 to 3 minutes, the amount of sodium oleate added is 100 to 150 g / t of magnetic concentrate.

5. The method for separating magnetic-red fine refractory iron ore according to claim 1, characterized in that: The fineness of the crushed product after the closed-circuit operation of crushing and screening is ≤12mm. After the crushed product is subjected to the closed-circuit operation of grinding and screening, more than 85% of the grinding products have a particle size of ≤400 mesh; after the grinding products are subjected to weak magnetic and strong magnetic classification operations, the magnetic separation concentrate obtained contains 40% to 50% TFe by weight, and the iron recovery rate is 70% to 90%.

6. [Corrected 06.02.2024 according to Rule 91] A magnetic-red fine refractory iron ore separation method according to claim 1, characterized in that: In the reverse flotation closed-circuit operation, the concentrate from the reverse flotation roughing enters the reverse flotation cleaning process, and the tailings from the reverse flotation roughing enters the reverse flotation scavenging process; When the concentrate enters the concentration process, the reverse flotation roughing concentrate is added with water to prepare a reverse flotation roughing concentrate slurry with a weight concentration of 30% to 40%, and sodium oleate is added and stirred for 2 to 3 minutes. The amount of sodium oleate added is 20 to 50 g / t of reverse flotation roughing concentrate slurry.

7. A magnetic-red fine refractory iron ore separation method according to claim 1 or 6, characterized in that: In the reverse flotation closed-circuit operation, when the reverse flotation scavenging is performed once, the concentrate obtained by the reverse flotation scavenging is returned to the flotation slurry, and reverse flotation roughing is performed again; when the reverse flotation roughing tailings are subjected to the reverse flotation scavenging twice, the concentrate obtained by the reverse flotation scavenging twice is mixed with the reverse flotation roughing tailings, and the first reverse flotation scavenging is performed together; When the reverse flotation rougher tailings are subjected to three reverse flotation scavengings, the concentrates obtained from the three reverse flotation scavengings are mixed with the tailings from the first reverse flotation scavenging and are subjected to the second reverse flotation scavenging together.

8. The method for separating magnetic-red fine refractory iron ore according to claim 1, characterized in that: The obtained reverse flotation concentrate contains TFe of 65.5% to 68% by weight, and the iron recovery rate is 70% to 90%.

9. A magnetic-red fine refractory iron ore separation method according to claim 1, characterized in that: The chemical composition of the fine-grained magnetic-hematite mixed ore is calculated by weight percentage as follows: TFe 25%-35%, CaO 0.1%-1.5%, MgO 0.1%-1.5%, SiO2 30%-40%, S 0.01%-0.1%, P 0.01%-0.1%, and the remainder is impurities.

10. A magnetic-red fine refractory iron ore separation method according to claim 1, characterized in that: The iron phase composition of the fine-grained magnetic-hematite mixed ore is as follows by weight: 25% to 35% hematite, 15% to 30% magnetite, 1% to 3% siderite, 0.1% to 1% pyrite, and the remainder is iron-containing silicate and other impurities.

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