Physical separation process for enriching titanium concentrate from iron separation tailings based on cooperation of multi-stage magnetic separation and high-frequency screening

Abstract

The invention belongs to the technical field of mineral processing and comprehensive utilization of resources, and particularly relates to a physical separation process for enriching titanium concentrate from iron separation tailings based on multi-stage magnetic separation and high-frequency screening collaboration.The physical separation process comprises the steps that firstly, the iron separation tailings and water are mixed and pretreated according to the mass ratio of 1: 2-1: 3, and then rough titanium concentrate is obtained through one-time flat plate high-intensity magnetic separation; and then high-frequency screening and grading are performed, oversize materials return to the ball mill, and undersize materials enter a subsequent process. And then gravity water separation enhanced classification is carried out, and titanium middlings are obtained in cooperation with a hydrocyclone. And finally, the titanium middlings are subjected to drying and dry magnetic separation, the titanium concentrate with the TiO2 grade larger than or equal to 48%, the sulfur content smaller than or equal to 0.1% and the recovery rate larger than or equal to 65% is obtained through successful separation, the TiO2 grade of the titanium concentrate larger than or equal to 48% is achieved through the synergistic effect of multi-stage magnetic separation and high-frequency screening, and the titanium concentrate TiO2 grade is improved by 25%-30% compared with a traditional magnetic separation technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of mineral processing and comprehensive resource utilization, and specifically relates to a physical separation process for enriching titanium concentrate from iron ore tailings based on the coordination of multi-stage magnetic separation and high-frequency screening. It is particularly suitable for the efficient recovery and resource utilization of titanium-containing magnetite tailings. Background Art

[0002] The existing titanium mineral recovery technology mainly has the following problems:

[0003] U.S. Patent No. 4192738A discloses a method for recovering iron from flotation tailings. This method uses wet high-intensity magnetic separation (WHIMS) to treat flotation tailings. However, this technology primarily targets iron recovery and does not consider titanium enrichment. Furthermore, it uses only a single magnetic separation process, resulting in insufficient recovery efficiency for weakly magnetic ilmenite.

[0004] Chinese patent CN101403036A discloses a method for separating ilmenite ore, which utilizes crushing, primary and secondary ball milling, low-intensity magnetic separation, high-intensity magnetic separation, tertiary ball milling, spiral separation, and concentrating to produce a fine titanium powder containing 45%-55%. While this method combines magnetic separation and gravity separation, it lacks a coordinated closed-loop design for high-frequency screening and magnetic separation, limiting its effectiveness in recovering fine-grained titanium minerals.

[0005] Chinese patent CN107597413B introduces a method for beneficiating ilmenite, which uses a flotation process to treat low-grade ilmenite. However, the chemical agents used in the flotation process not only increase process costs but also bring environmental pollution risks.

[0006] In general, the existing technology has the following limitations in the recovery of titanium from iron ore tailings:

[0007] 1. Low efficiency of single separation process: Traditional titanium recovery from iron ore tailings relies on single magnetic separation (such as drum magnetic separator), which is not very effective for weakly magnetic ilmenite (magnetic susceptibility < 5×10 -7 m 3 Inadequate separation efficiency (1000 tonnes / kg) resulted in titanium recoveries generally below 50%, and residual TiO2 in tailings exceeding 3%. High-frequency screening and magnetic separation processes failed to form a closed-loop synergy, leading to a significant loss of fine-grained titanium minerals (-0.074 mm) due to insufficient screening accuracy (error rate >15%).

[0008] 2. Conventional processes are lengthy and energy-intensive: The conventional process requires multiple stages of gravity separation (e.g., spiral chutes) and flotation, increasing equipment investment costs by 40%. Flotation reagents (e.g., hydroxamic acid) also introduce environmental pollution risks. The dry-wet process is poorly integrated, resulting in a high return rate of 25% for titanium middlings after drying, resulting in an overall energy consumption of >180 kW·h per ton of titanium concentrate.

[0009] 3. The degree of resource utilization of tailings is insufficient: magnetically separated tailings are directly stored (containing TiO2 2-4%), and resource recovery is not achieved through sand making and re-selection; tailings (SiO2>60%) are not graded and utilized, and the utilization rate of building materials is less than 30%.

[0010] 4. Poor particle size adaptability: The particle size distribution of iron ore tailings is wide (0.1-5mm). The traditional process requires additional crushing for the separation of coarse particles (+0.5mm) and lacks effective enrichment methods for fine particles (-0.038mm), resulting in a difference in the recovery rate of all particle sizes of >40%.

[0011] Therefore, there is an urgent need to develop an efficient, environmentally friendly and adaptable process for enriching titanium concentrate from iron ore tailings to improve the recovery rate of titanium resources, reduce energy consumption and achieve comprehensive utilization of resources. Summary of the Invention

[0012] In response to the above problems in the prior art, the present invention provides a physical separation process for enriching titanium concentrate from iron ore tailings based on the synergy of multi-stage magnetic separation and high-frequency screening, aiming to achieve the following technical goals:

[0013] 1. Build a cascade sorting system, combining primary intensive sorting with secondary refining and sorting to significantly improve the grade of titanium concentrate;

[0014] 2. Establish a full-size closed-loop recovery system, and achieve efficient recovery of titanium minerals of different size through a dynamic adjustment mechanism of over-screen sand making and under-screen grinding;

[0015] 3. Optimize energy consumption and environmental performance. Through the concentrated return water of the wet magnetic separation system and the waste heat recovery of the dry magnetic separation system, the overall energy consumption is reduced and the environmental pollution risk caused by the use of chemical agents is avoided.

[0016] The present invention provides a physical separation process for enriching titanium concentrate from iron ore tailings based on the coordination of multi-stage magnetic separation and high-frequency screening, comprising the following steps:

[0017] (1) Raw material pretreatment: Mix the iron ore tailings with water in a mass ratio of 1:2 to 1:3, control the slurry concentration to 25% to 30%, adjust the pH value to 6.5 to 7.5, and use a stirring barrel with a speed of 80 to 120 rpm to evenly disperse the slurry. The stirring time is ≥ 10 min.

[0018] (2) Single-stage flat plate strong magnetic separation: Use a vertical ring high gradient magnetic separator with a background magnetic field strength of 1.2 to 1.5 T, a separation gap of 5 to 8 mm, a magnetic medium of 2 mm diameter and 3 mm spacing of magnetic conductive stainless steel rods, a pulse frequency of ≥ 300 times / min, and a slurry flow rate of 1.0 to 1.5 m 3 / h, obtaining a titanium crude concentrate with a TiO2 grade of 15% to 18%;

[0019] (3) High-frequency screening and grading: A double-layer high-frequency vibrating screen with a vibration frequency of 1800-2400 times / min and an amplitude of 2-4 mm is used. The upper screen hole is 0.1 mm and the lower screen hole is 0.074 mm. The material on the screen is returned to the ball mill for re-crushing. The ball filling rate of the ball mill is 30%-40%. The material under the screen enters the subsequent sorting process, of which the particle size of ≤0.074 mm accounts for ≥90%;

[0020] (4) Gravity water separation and enhanced classification: Use a spiral chute with an inclination angle of 15° to 20° and a trough surface made of polyurethane, and the slurry flow rate is 0.8 to 1.2 m 3 / h; and cooperate with a hydrocyclone with an inlet pressure of 0.15-0.25MPa and a separation particle size of 10-25μm to obtain titanium ore with a TiO2 grade of ≥25% and a sulfur content of ≤0.3%;

[0021] (5) Secondary flat plate high-intensity magnetic separation: A double-ring high-gradient magnetic separator with a magnetic field strength of 0.8 to 1.0 T is used. The magnetic medium is a composite magnetic block of neodymium iron boron and magnetic conductive stainless steel. The pulse frequency is 350 to 400 times / min. The slurry concentration is adjusted to 20% to 25%, and titanium ore with a TiO2 grade of 35% to 38% is obtained.

[0022] (6) Dry magnetic separation of titanium middlings: Dry the titanium middlings at 80-100°C for 20-30 min, control the moisture content to ≤3%, and maintain the particle size of -200 mesh at ≥85% after drying; use a permanent magnetic drum dry magnetic separator with a magnetic field strength of 0.4-0.6T and a drum speed of 60-80rpm for final purification to obtain titanium concentrate with a TiO2 grade of ≥48%, a sulfur content of ≤0.1%, and a recovery rate of ≥65%.

[0023] Preferably, the high-frequency screening system and the ball milling system in step (3) constitute a closed-loop control system, which monitors the particle size of the material on the screen in real time through an online particle size analyzer, and automatically adjusts the ball mill speed to 15-25 rpm and the steel ball ratio, wherein the steel ball diameter is Φ30-50 mm, to ensure that the crushing efficiency is maximized and the over-grinding rate is ≤5%.

[0024] Preferably, a flow stabilizer is added in the gravity water separation stage in step (4) to control the slurry flow rate fluctuation to ≤±0.1m 3 / h, improving the sorting stability; at the same time, the tailings of the primary magnetic separation are subjected to secondary sorting in a spiral chute to recover the lost fine-grained ilmenite.

[0025] Preferably, a high-pressure airflow nozzle is added to the inlet of the dry magnetic separator in step (6) with a pressure of 0.3 to 0.5 MPa to remove the fine mineral mud adsorbed on the surface of the mineral and avoid charge interference; at the same time, a tungsten carbide coating with a thickness of 50 to 100 μm is used on the surface of the drum to reduce mineral adhesion.

[0026] In addition, the magnetic field intensity of each stage of magnetic separation decreases gradually, from 1.2 to 1.5 T for the first magnetic separation, from 0.8 to 1.0 T for the second magnetic separation, and from 0.4 to 0.6 T for the dry magnetic separation, thus achieving selective separation for different magnetic minerals.

[0027] The hydrocyclone in step (4) can effectively recover -25 μm fine-particle titanium minerals by controlling the inlet pressure to 0.15-0.25 MPa.

[0028] After the high-frequency screening in step (3) is completed, the gravity water separation tailings are put into the high-frequency screen for classification for the second time, and the classification requirements are the same as those in step (3).

[0029] The drying system in step (6) adopts a waste heat recovery device, with a heat energy utilization rate of ≥80%, thereby reducing energy consumption.

[0030] The process of the present invention does not require the addition of any chemical agents throughout the entire process; after the process wastewater is treated in a sedimentation tank, the suspended matter content is ≤50 mg / L, and the reuse rate is ≥90%.

[0031] The sorted tailings in the process are finely ground to -25μm with a proportion of ≥80%, mixed with cement at a mass ratio of 1:3, and pressed into unfired bricks with a compressive strength of ≥15MPa, thereby realizing resource utilization of the tailings.

[0032] The physical separation process for enriching titanium concentrate from iron ore tailings based on the synergy of multi-stage magnetic separation and high-frequency screening provided by the present invention has the following beneficial effects:

[0033] 1. Significantly improved sorting indicators: Through the synergistic effect of multi-stage magnetic separation and high-frequency screening, the titanium concentrate TiO2 grade is ≥48%, the sulfur content is ≤0.1%, and the comprehensive recovery rate is ≥65%, which is 25% to 30% higher than the traditional magnetic separation process;

[0034] 2. Significantly reduced energy consumption: Through concentrated return water from the wet magnetic separation system and waste heat recovery from the dry magnetic separation system, the power consumption per ton of ore processed is reduced to ≤15kWh, a 50% reduction compared to the flotation process. At the same time, the closed-loop design enables coarse particles to be recycled and crushed, reducing energy consumption.

[0035] 3. Obvious environmental advantages: No chemical agents are added throughout the process, and the wastewater recycling rate is ≥90%, reducing the risk of environmental pollution; the tailings can be directly used to prepare building materials after treatment, and the resource utilization rate reaches 100%;

[0036] 4. Enhanced full-size particle size processing capacity: Through the dynamic adjustment mechanism of "sand making above the screen - grinding below the screen", the recovery rate of titanium minerals in the full size range of 0.1-5mm is greater than 65%, which significantly improves the adaptability to materials of different particle sizes;

[0037] 5. High degree of intelligent process control: Through online particle size analyzer, real-time monitoring of magnetic field strength and other equipment, automatic adjustment of process parameters is achieved, which improves the sorting stability and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a process flow chart for the tiered separation of titanium concentrate from iron ore tailings according to the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood by those skilled in the art that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0040] Example 1

[0041] This embodiment provides a physical separation process for enriching titanium concentrate from iron ore tailings based on the synergy of multi-stage magnetic separation and high-frequency screening. The raw material is titanium-containing tailings produced by an iron ore beneficiation plant, with a TiO2 content of 5.3%, an iron content of 12.5%, and a particle size distribution of 0.1-4.5 mm. The process includes the following steps:

[0042] (1) Raw material pretreatment: The iron ore tailings were mixed with water in a mass ratio of 1:2.5, the slurry concentration was controlled to 27%, the pH value was adjusted to 7.0, and the slurry was evenly dispersed in a stirring barrel at a speed of 100 rpm for 12 min;

[0043] (2) Single-stage flat plate strong magnetic separation: A vertical ring high gradient magnetic separator with a background magnetic field strength of 1.3T is used, the separation gap is 6mm, the magnetic medium is a magnetic conductive stainless steel rod with a diameter of 2mm and a spacing of 3mm, the pulse frequency is 320 times / min, and the slurry flow rate is 1.2m 3 / h, obtaining a titanium crude concentrate with a TiO2 grade of 16.5%;

[0044] (3) High-frequency screening and grading: A double-layer high-frequency vibrating screen with a vibration frequency of 2000 times / min and an amplitude of 3 mm is used. The upper screen hole is 0.1 mm and the lower screen hole is 0.074 mm. The material on the screen is returned to the ball mill for re-crushing. The ball filling rate of the ball mill is 35%; the material under the screen enters the subsequent sorting process, of which the particle size of ≤0.074 mm accounts for 92%;

[0045] (4) Gravity water separation and enhanced classification: a spiral chute with an inclination angle of 18° and a trough surface made of polyurethane is used, and the slurry flow rate is 1.0m 3 / h; and with the help of a hydrocyclone with an inlet pressure of 0.2MPa and a separation particle size of 15μm, titanium ore with a TiO2 grade of 26.3% and a sulfur content of 0.25% was obtained;

[0046] (5) Secondary flat plate high-intensity magnetic separation: A double-ring high-gradient magnetic separator with a magnetic field strength of 0.9T was used. The magnetic medium was a composite magnetic block of NdFeB and magnetically conductive stainless steel. The pulse frequency was 375 times / min. The slurry concentration was adjusted to 22%, and a titanium ore with a TiO2 grade of 36.2% was obtained.

[0047] (6) Dry magnetic separation of titanium middlings: Dry the titanium middlings at 90°C for 25 minutes, control the moisture content to 2.5%, and maintain the particle size of -200 mesh at 87% after drying. Use a permanent magnetic drum dry magnetic separator with a magnetic field strength of 0.5T and a drum speed of 70rpm for final purification to obtain titanium concentrate with a TiO2 grade of 48.5%, a sulfur content of 0.09%, and a recovery rate of 66.3%.

[0048] In this embodiment, the high-frequency screening system and the ball milling system constitute a closed-loop control system. The particle size of the material on the screen is monitored in real time by an online particle size analyzer, and the ball mill speed is automatically adjusted to 20 rpm and the steel ball ratio is automatically adjusted. The steel ball diameter is Φ40 mm to ensure maximum crushing efficiency and an over-grinding rate of 4.5%.

[0049] A flow stabilizer is added during the gravity water separation stage to control the slurry flow rate fluctuation within ±0.08m 3 / h, improving the sorting stability; at the same time, the tailings of the first magnetic separation are subjected to secondary sorting in a spiral chute to recover the lost fine-grained ilmenite.

[0050] A high-pressure airflow nozzle with a pressure of 0.4MPa is added to the inlet of the dry magnetic separator to remove fine mineral mud adsorbed on the surface of the mineral and avoid charge interference; at the same time, the drum surface is coated with tungsten carbide with a thickness of 75μm to reduce mineral adhesion.

[0051] The magnetic field intensity of each stage of magnetic separation decreases gradually, with the first magnetic separation being 1.3T, the second magnetic separation being 0.9T, and the dry magnetic separation being 0.5T, thus forming a selective separation for different magnetic minerals.

[0052] The hydrocyclone can effectively recover -25μm fine-grained titanium minerals by controlling the inlet pressure to 0.2MPa. After high-frequency screening, the gravity water separation tailings are fed into the high-frequency screen for secondary classification. The classification requirements are the same as those in step (3).

[0053] The drying system utilizes a waste heat recovery device, achieving a heat utilization rate of 82%, reducing energy consumption. No chemical agents are added throughout the process, and after treatment in the sedimentation tank, the suspended solids content of the process wastewater is reduced to 45mg / L, with a reuse rate of 92%.

[0054] After the sorted tailings are finely ground to -25μm, accounting for 83%, they are mixed with cement at a mass ratio of 1:3 and pressed into unfired bricks with a compressive strength of 16.3MPa, realizing the resource utilization of the tailings.

[0055] Example 2

[0056] This embodiment provides a physical separation process for enriching titanium concentrate from iron tailings based on the synergy of multi-stage magnetic separation and high-frequency screening. The raw material is titanium-containing tailings produced by a vanadium-titanium magnetite beneficiation plant, with a TiO2 content of 6.8%, an iron content of 10.2%, and a particle size distribution of 0.1-5.0 mm. The process includes the following steps:

[0057] (1) Raw material pretreatment: The iron ore tailings were mixed with water in a mass ratio of 1:3, the slurry concentration was controlled to 25%, the pH value was adjusted to 6.8, and the slurry was evenly dispersed in a stirring barrel at a speed of 90 rpm for 15 min;

[0058] (2) Single-stage flat plate strong magnetic separation: A vertical ring high gradient magnetic separator with a background magnetic field strength of 1.5T is used, the separation gap is 5mm, the magnetic medium is a magnetic conductive stainless steel rod with a diameter of 2mm and a spacing of 3mm, the pulse frequency is 350 times / min, and the slurry flow rate is 1.0m 3 / h, obtaining a titanium crude concentrate with a TiO2 grade of 17.8%;

[0059] (3) High-frequency screening and grading: A double-layer high-frequency vibrating screen with a vibration frequency of 2400 times / min and an amplitude of 4 mm is used. The upper screen hole is 0.1 mm and the lower screen hole is 0.074 mm. The material on the screen is returned to the ball mill for re-crushing. The ball filling rate of the ball mill is 40%. The material under the screen enters the subsequent sorting process, of which the particle size of ≤0.074 mm accounts for 95%;

[0060] (4) Gravity water separation and enhanced classification: a spiral chute with an inclination angle of 20° and a trough surface made of polyurethane is used, and the slurry flow rate is 0.8m 3 / h; and with a hydrocyclone with an inlet pressure of 0.25MPa and a separation particle size of 10μm, titanium ore with a TiO2 grade of 28.2% and a sulfur content of 0.18% was obtained;

[0061] (5) Secondary flat plate high-intensity magnetic separation: A double-ring high-gradient magnetic separator with a magnetic field strength of 0.8T was used. The magnetic medium was a composite magnetic block of NdFeB and magnetically conductive stainless steel. The pulse frequency was 400 times / min, and the slurry concentration was adjusted to 20%. A titanium ore with a TiO2 grade of 37.5% was obtained.

[0062] (6) Dry magnetic separation of titanium middlings: Dry the titanium middlings at 100°C for 20 minutes, control the moisture content to 2.0%, and maintain the particle size of -200 mesh at 90% after drying; use a permanent magnetic drum dry magnetic separator with a magnetic field strength of 0.6T and a drum speed of 80rpm for final purification to obtain titanium concentrate with a TiO2 grade of 50.2%, a sulfur content of 0.07%, and a recovery rate of 68.5%.

[0063] In this embodiment, the high-frequency screening system and the ball milling system constitute a closed-loop control system. The particle size of the material on the screen is monitored in real time by an online particle size analyzer, and the ball mill speed is automatically adjusted to 25 rpm and the steel ball ratio is automatically adjusted. The steel ball diameter is Φ30 mm, ensuring maximum crushing efficiency and an over-grinding rate of 3.5%.

[0064] A flow stabilizer is added during the gravity water separation stage to control the slurry flow rate fluctuation within ±0.05m 3 / h, improving the sorting stability; at the same time, the tailings of the first magnetic separation are subjected to secondary sorting in a spiral chute to recover the lost fine-grained ilmenite.

[0065] A high-pressure airflow nozzle with a pressure of 0.5MPa is added to the inlet of the dry magnetic separator to remove fine mineral mud adsorbed on the surface of the mineral and avoid charge interference; at the same time, the drum surface is coated with tungsten carbide with a thickness of 100μm to reduce mineral adhesion.

[0066] The magnetic field intensity of each stage of magnetic separation decreases gradually, with the first magnetic separation being 1.5T, the second magnetic separation being 0.8T, and the dry magnetic separation being 0.6T, thus forming a selective separation for different magnetic minerals.

[0067] The hydrocyclone can effectively recover -25μm fine-grained titanium minerals by controlling the inlet pressure to 0.25MPa. After high-frequency screening, the gravity water separation tailings are fed into the high-frequency screen for secondary classification. The classification requirements are the same as those in step (3).

[0068] The drying system utilizes a waste heat recovery device, achieving a heat utilization rate of 85%, reducing energy consumption. No chemical agents are added throughout the process, and after treatment in the sedimentation tank, the suspended solids content of the process wastewater is reduced to 38mg / L, with a reuse rate of 95%.

[0069] After the sorted tailings are finely ground to -25μm, accounting for 88%, they are mixed with cement at a mass ratio of 1:3 and pressed into unfired bricks with a compressive strength of 18.5MPa, realizing the resource utilization of the tailings.

[0070] Example 3

[0071] This embodiment provides a physical separation process for enriching titanium concentrate from iron ore tailings based on the synergy of multi-stage magnetic separation and high-frequency screening. The raw material is titanium-containing tailings produced by an iron ore beneficiation plant, with a TiO2 content of 4.2%, an iron content of 14.8%, and a particle size distribution of 0.1-3.5 mm. The process includes the following steps:

[0072] (1) Raw material pretreatment: The iron ore tailings were mixed with water in a mass ratio of 1:2, the slurry concentration was controlled to 30%, the pH value was adjusted to 7.5, and the slurry was evenly dispersed in a stirring barrel at a speed of 120 rpm for 10 min;

[0073] (2) Single-stage flat plate strong magnetic separation: A vertical ring high gradient magnetic separator with a background magnetic field strength of 1.2T is used, the separation gap is 8mm, the magnetic medium is a magnetic conductive stainless steel rod with a diameter of 2mm and a spacing of 3mm, the pulse frequency is 300 times / min, and the slurry flow rate is 1.5m 3 / h, obtaining a titanium crude concentrate with a TiO2 grade of 15.0%;

[0074] (3) High-frequency screening and grading: A double-layer high-frequency vibrating screen with a vibration frequency of 1800 times / min and an amplitude of 2 mm is used. The upper screen hole is 0.1 mm and the lower screen hole is 0.074 mm. The material on the screen is returned to the ball mill for re-crushing. The ball filling rate of the ball mill is 30%. The material under the screen enters the subsequent sorting process, of which the particle size of ≤0.074 mm accounts for 90%;

[0075] (4) Gravity water separation and enhanced classification: a spiral chute with an inclination angle of 15° and a trough surface made of polyurethane is used, and the slurry flow rate is 1.2m 3 / h; and with a hydrocyclone with an inlet pressure of 0.15MPa and a separation particle size of 20μm, titanium ore with a TiO2 grade of 25.0% and a sulfur content of 0.30% is obtained;

[0076] (5) Secondary flat plate high-intensity magnetic separation: A double-ring high-gradient magnetic separator with a magnetic field strength of 1.0T was used. The magnetic medium was a composite magnetic block of NdFeB and magnetically conductive stainless steel. The pulse frequency was 350 times / min and the slurry concentration was adjusted to 25%. A titanium ore with a TiO2 grade of 35.0% was obtained.

[0077] (6) Dry magnetic separation of titanium middlings: Dry the titanium middlings at 80°C for 30 min, control the moisture content to 3.0%, and maintain the particle size of -200 mesh at 85% after drying. Use a permanent magnetic drum dry magnetic separator with a magnetic field strength of 0.4T and a drum speed of 60rpm for final purification to obtain titanium concentrate with a TiO2 grade of 48.0%, a sulfur content of 0.10%, and a recovery rate of 65.0%.

[0078] In this embodiment, the high-frequency screening system and the ball milling system constitute a closed-loop control system. The particle size of the material on the screen is monitored in real time by an online particle size analyzer, and the ball mill speed is automatically adjusted to 15 rpm and the steel ball ratio is automatically adjusted. The steel ball diameter is Φ50 mm to ensure maximum crushing efficiency and an over-grinding rate of 5.0%.

[0079] A flow stabilizer is added during the gravity water separation stage to control the slurry flow rate fluctuation within ±0.1m 3 / h, improving the sorting stability; at the same time, the tailings of the first magnetic separation are subjected to secondary sorting in a spiral chute to recover the lost fine-grained ilmenite.

[0080] A high-pressure airflow nozzle with a pressure of 0.3MPa is added to the inlet of the dry magnetic separator to remove fine mineral mud adsorbed on the surface of the mineral and avoid charge interference; at the same time, the drum surface is coated with tungsten carbide with a thickness of 50μm to reduce mineral adhesion.

[0081] The magnetic field intensity of each stage of magnetic separation decreases gradually, with the first magnetic separation being 1.2T, the second magnetic separation being 1.0T, and the dry magnetic separation being 0.4T, thus forming a selective separation for different magnetic minerals.

[0082] The hydrocyclone can effectively recover -25μm fine-grained titanium minerals by controlling the inlet pressure to 0.15MPa. After high-frequency screening, the gravity water separation tailings are fed into the high-frequency screen for secondary classification. The classification requirements are the same as those in step (3).

[0083] The drying system utilizes a waste heat recovery device, achieving a heat utilization rate of 80%, reducing energy consumption. No chemical agents are added throughout the process, and after treatment in the sedimentation tank, the suspended solids content of the process wastewater is reduced to 50mg / L, with a reuse rate of 90%.

[0084] After the sorted tailings are finely ground to -25μm, accounting for 80%, they are mixed with cement at a mass ratio of 1:3 and pressed into unfired bricks with a compressive strength of 15.0MPa, realizing the resource utilization of the tailings.

[0085] Example 4

[0086] This embodiment provides a physical separation process for enriching titanium concentrate from iron tailings based on the synergy of multi-stage magnetic separation and high-frequency screening. The raw material is titanium-containing tailings produced by a vanadium-titanium magnetite beneficiation plant, with a TiO2 content of 7.8%, an iron content of 9.5%, and a particle size distribution of 0.15-4.8 mm. The process includes the following steps:

[0087] (1) Raw material pretreatment: The iron ore tailings were mixed with water at a mass ratio of 1:2.8, the slurry concentration was controlled to 26%, the pH value was adjusted to 7.2, and the slurry was evenly dispersed in a stirring barrel at a speed of 110 rpm for 13 min;

[0088] (2) Single-plate strong magnetic separation: A vertical ring high gradient magnetic separator with a background magnetic field strength of 1.4T was used, the separation gap was 7mm, the magnetic medium was a magnetic conductive stainless steel rod with a diameter of 2mm and a spacing of 3mm, the pulse frequency was 335 times / min, and the slurry flow rate was 1.3m 3 / h, obtaining a titanium crude concentrate with a TiO2 grade of 17.2%;

[0089] (3) High-frequency screening and grading: A double-layer high-frequency vibrating screen with a vibration frequency of 2200 times / min and an amplitude of 3.5 mm is used. The upper screen hole is 0.1 mm and the lower screen hole is 0.074 mm. The material on the screen is returned to the ball mill for re-crushing. The ball filling rate of the ball mill is 38%. The material under the screen enters the subsequent sorting process, of which the particle size of ≤0.074 mm accounts for 93%;

[0090] (4) Gravity water separation and enhanced classification: a spiral chute with an inclination angle of 17° and a trough surface made of polyurethane is used, and the slurry flow rate is 1.1m 3 / h; and with the help of a hydrocyclone with an inlet pressure of 0.22MPa and a separation particle size of 12μm, titanium ore with a TiO2 grade of 27.8% and a sulfur content of 0.20% was obtained;

[0091] (5) Secondary flat plate high-intensity magnetic separation: A double-ring high-gradient magnetic separator with a magnetic field strength of 0.85T was used. The magnetic medium was a composite magnetic block of NdFeB and magnetically conductive stainless steel. The pulse frequency was 385 times / min. The slurry concentration was adjusted to 23%, and a titanium ore with a TiO2 grade of 37.0% was obtained.

[0092] (6) Dry magnetic separation of titanium middlings: Dry the titanium middlings at 95°C for 23 minutes, control the moisture content to 2.2%, and maintain the particle size of -200 mesh at 89% after drying. Use a permanent magnetic drum dry magnetic separator with a magnetic field strength of 0.55T and a drum speed of 75rpm for final purification to obtain titanium concentrate with a TiO2 grade of 49.5%, a sulfur content of 0.08%, and a recovery rate of 67.5%.

[0093] In this embodiment, the high-frequency screening system and the ball milling system constitute a closed-loop control system. The particle size of the material on the screen is monitored in real time by an online particle size analyzer, and the ball mill speed is automatically adjusted to 22 rpm and the steel ball ratio is automatically adjusted. The steel ball diameter is Φ35 mm, ensuring maximum crushing efficiency and an over-grinding rate of 4.0%.

[0094] A flow stabilizer is added during the gravity water separation stage to control the slurry flow rate fluctuation within ±0.07m 3 / h, improving the sorting stability; at the same time, the tailings of the first magnetic separation are subjected to secondary sorting in a spiral chute to recover the lost fine-grained ilmenite.

[0095] A high-pressure airflow nozzle with a pressure of 0.45MPa is added to the inlet of the dry magnetic separator to remove fine mineral mud adsorbed on the surface of the mineral and avoid charge interference; at the same time, the drum surface is coated with tungsten carbide with a thickness of 85μm to reduce mineral adhesion.

[0096] The magnetic field intensity of each stage of magnetic separation decreases gradually, with the first magnetic separation being 1.4T, the second magnetic separation being 0.85T, and the dry magnetic separation being 0.55T, thus forming a selective separation for different magnetic minerals.

[0097] The hydrocyclone can effectively recover -25μm fine-grained titanium minerals by controlling the inlet pressure to 0.22MPa. After high-frequency screening, the gravity water separation tailings are fed into the high-frequency screen for secondary classification. The classification requirements are the same as those in step (3).

[0098] The drying system utilizes a waste heat recovery device, achieving a heat utilization rate of 83%, reducing energy consumption. No chemical agents are added throughout the process, and after treatment in the sedimentation tank, the suspended solids content of the process wastewater is reduced to 42 mg / L, with a reuse rate of 93%.

[0099] After the sorted tailings are finely ground to -25μm, accounting for 85%, they are mixed with cement at a mass ratio of 1:3 and pressed into unfired bricks with a compressive strength of 17.2MPa, realizing the resource utilization of the tailings.

[0100] Example 5

[0101] This embodiment provides a physical separation process for enriching titanium concentrate from iron ore tailings based on the synergy of multi-stage magnetic separation and high-frequency screening. The raw material is titanium-containing tailings produced by an iron ore beneficiation plant, with a TiO2 content of 3.5%, an iron content of 15.5%, and a particle size distribution of 0.08-4.0 mm. The process includes the following steps:

[0102] (1) Raw material pretreatment: The iron ore tailings were mixed with water in a mass ratio of 1:3, the slurry concentration was controlled to 25%, the pH value was adjusted to 6.5, and the slurry was evenly dispersed in a stirring barrel at a speed of 85 rpm for 11 min;

[0103] (2) Single-plate strong magnetic separation: A vertical ring high gradient magnetic separator with a background magnetic field strength of 1.45T is used, the separation gap is 5.5mm, the magnetic medium is a magnetic conductive stainless steel rod with a diameter of 2mm and a spacing of 3mm, the pulse frequency is 330 times / min, and the slurry flow rate is 1.1m 3 / h, obtaining a titanium crude concentrate with a TiO2 grade of 15.5%;

[0104] (3) High-frequency screening and grading: A double-layer high-frequency vibrating screen with a vibration frequency of 1900 times / min and an amplitude of 2.5 mm is used. The upper screen hole is 0.1 mm and the lower screen hole is 0.074 mm. The material on the screen is returned to the ball mill for re-crushing. The ball filling rate of the ball mill is 32%; the material under the screen enters the subsequent sorting process, of which the particle size of ≤0.074 mm accounts for 91%;

[0105] (4) Gravity water separation and enhanced classification: a spiral chute with an inclination angle of 16° and a trough surface made of polyurethane is used, and the slurry flow rate is 0.9m 3 / h; and with a hydrocyclone with an inlet pressure of 0.18MPa and a separation particle size of 18μm, titanium ore with a TiO2 grade of 25.8% and a sulfur content of 0.28% was obtained;

[0106] (5) Secondary flat plate high-intensity magnetic separation: A double-ring high-gradient magnetic separator with a magnetic field strength of 0.95T was used. The magnetic medium was a composite magnetic block of NdFeB and magnetically conductive stainless steel. The pulse frequency was 360 times / min. The slurry concentration was adjusted to 21%, and titanium ore with a TiO2 grade of 35.8% was obtained.

[0107] (6) Dry magnetic separation of titanium middlings: Dry the titanium middlings at 85°C for 28 minutes, control the moisture content to 2.8%, and maintain the particle size of -200 mesh at 86% after drying. Use a permanent magnetic drum dry magnetic separator with a magnetic field strength of 0.45T and a drum speed of 65rpm for final purification to obtain titanium concentrate with a TiO2 grade of 48.3%, a sulfur content of 0.09%, and a recovery rate of 65.6%.

[0108] In this embodiment, the high-frequency screening system and the ball milling system constitute a closed-loop control system. The particle size of the material on the screen is monitored in real time by an online particle size analyzer, and the ball mill speed is automatically adjusted to 18 rpm and the steel ball ratio is automatically adjusted. The steel ball diameter is Φ45 mm, ensuring maximum crushing efficiency and an over-grinding rate of 4.8%.

[0109] A flow stabilizer is added during the gravity water separation stage to control the slurry flow rate fluctuation within ±0.09m 3 / h, improving the sorting stability; at the same time, the tailings of the first magnetic separation are subjected to secondary sorting in a spiral chute to recover the lost fine-grained ilmenite.

[0110] A high-pressure airflow nozzle with a pressure of 0.35MPa is added to the inlet of the dry magnetic separator to remove fine mineral mud adsorbed on the surface of the mineral and avoid charge interference; at the same time, the drum surface is coated with tungsten carbide with a thickness of 60μm to reduce mineral adhesion.

[0111] The magnetic field intensity of each stage of magnetic separation decreases gradually, with the first magnetic separation being 1.45T, the second magnetic separation being 0.95T, and the dry magnetic separation being 0.45T, thus forming a selective separation for different magnetic minerals.

[0112] The hydrocyclone can effectively recover -25μm fine-grained titanium minerals by controlling the inlet pressure to 0.18MPa. After high-frequency screening, the gravity water separation tailings are fed into the high-frequency screen for secondary classification. The classification requirements are the same as those in step (3).

[0113] The drying system utilizes a waste heat recovery device, achieving a heat utilization rate of 81%, reducing energy consumption. No chemical agents are added throughout the process, and after treatment in the sedimentation tank, the suspended solids content of the process wastewater is reduced to 48mg / L, with a reuse rate of 91%.

[0114] After the sorted tailings are finely ground to -25μm, accounting for 82%, they are mixed with cement at a mass ratio of 1:3 and pressed into unfired bricks with a compressive strength of 15.8MPa, realizing the resource utilization of the tailings.

[0115] Comparative Example 1

[0116] This comparative example uses a traditional single magnetic separation process to treat iron tailings to enrich titanium concentrate. The raw materials are the same as those in Example 1, with a TiO2 content of 5.3%, an iron content of 12.5%, and a particle size distribution of 0.1-4.5 mm. The process flow is as follows:

[0117] (1) Raw material pretreatment: The iron ore tailings were mixed with water in a mass ratio of 1:2.5, the slurry concentration was controlled to 27%, the pH value was adjusted to 7.0, and the slurry was evenly dispersed in a stirring barrel at a speed of 100 rpm for 12 min;

[0118] (2) Primary magnetic separation: A vertical ring high gradient magnetic separator with a background magnetic field strength of 1.3 T was used for magnetic separation to obtain a titanium crude concentrate with a TiO2 grade of 16.5%;

[0119] (3) Secondary magnetic separation: The titanium concentrate was dried at 90°C for 25 min and then subjected to secondary magnetic separation using a permanent magnetic drum dry magnetic separator with a magnetic field strength of 0.5 T to obtain a titanium concentrate with a TiO2 grade of 38.2% and a recovery rate of 42.5%.

[0120] Compared with Example 1, this comparative example lacks high-frequency screening and classification, gravity water separation and enhanced classification, and a complete multi-stage magnetic separation system. The final product TiO2 grade is only 38.2% (lower than 48.5% in Example 1), and the recovery rate is only 42.5% (lower than 66.3% in Example 1). This shows that the multi-stage magnetic separation and high-frequency screening synergistic process of the present invention can significantly improve the grade and recovery rate of titanium concentrate.

[0121] Comparative Example 2

[0122] This comparative example uses a flotation process to treat iron tailings to enrich titanium concentrate. The raw materials are the same as those in Example 2, with a TiO2 content of 6.8%, an iron content of 10.2%, and a particle size distribution of 0.1-5.0 mm. The process flow is as follows:

[0123] (1) Raw material pretreatment: After the iron ore tailings are ball-milled to -0.074 mm and accounted for ≥90%, they are mixed with water at a mass ratio of 1:3, the slurry concentration is controlled to 25%, and the pH value is adjusted to 6.8;

[0124] (2) Rough flotation: Sodium oleate was added as a collector (dosage 800 g / t) and pine oil as a frother (dosage 100 g / t), and rough flotation was performed in a flotation machine to obtain a rough concentrate with a TiO2 grade of 20.5%;

[0125] (3) Flotation: The coarse concentrate was subjected to secondary flotation and concentration, and sodium oleate (dosage 400 g / t) and pine oil (dosage 50 g / t) were added to obtain titanium concentrate with a TiO2 grade of 46.8% and a recovery rate of 58.2%.

[0126] Compared with Example 2, this comparative example uses chemical reagents, which not only increases process costs but also poses environmental risks. Furthermore, its overall energy consumption is 28.5 kWh / t (higher than the 14.2 kWh / t in Example 2), and its recovery rate is 58.2% (lower than the 68.5% in Example 2). This demonstrates that the physical separation process of the present invention offers significant environmental and energy advantages over flotation processes.

[0127] Comparative Example 3

[0128] This comparative example uses a single high-frequency screening process to treat iron tailings to enrich titanium concentrate. The raw materials are the same as those in Example 3, with a TiO2 content of 4.2%, an iron content of 14.8%, and a particle size distribution of 0.1-3.5 mm. The process flow is as follows:

[0129] (1) Raw material pretreatment: The iron ore tailings were mixed with water in a mass ratio of 1:2, the slurry concentration was controlled to 30%, the pH value was adjusted to 7.5, and the slurry was evenly dispersed in a stirring barrel at a speed of 120 rpm for 10 min;

[0130] (2) High-frequency screening and grading: The high-frequency vibrating screen with a vibration frequency of 1800 times / min and an amplitude of 2 mm is used for screening, and the screen opening is 0.074 mm. The material on the screen is returned to the ball mill for further crushing;

[0131] (3) Gravity separation: The undersize material is passed through a spiral chute for gravity separation to obtain titanium concentrate with a TiO2 grade of 30.5% and a recovery rate of 38.2%.

[0132] Compared with Example 3, this comparative example lacks a multi-stage magnetic separation system and a complete coordinated processing flow, and the final product TiO2 grade is only 30.5% (lower than 48.0% in Example 3), and the recovery rate is only 38.2% (lower than 65.0% in Example 3). This shows that the coordinated process of multi-stage magnetic separation and high-frequency screening of the present invention has a significant effect on improving the grade and recovery rate of titanium concentrate.

[0133] To evaluate the performance of the process of the present invention, the above-mentioned examples and comparative examples were systematically tested, with test indicators including titanium concentrate grade, recovery rate, energy consumption, and environmental protection indicators. The test results are shown in Table 1.

[0134] Table 1 Performance test results of various embodiments and comparative examples

[0135]

[0136] As can be seen from Table 1, the process provided by the present invention is superior to the comparative example in terms of titanium concentrate grade, recovery rate, energy consumption and environmental performance. This is specifically reflected in the following aspects:

[0137] 1. Titanium Concentrate Grade: The TiO2 grade of the titanium concentrate obtained by the process of the present invention (Examples 1-5) was ≥48.0%, with a maximum of 50.2% (Example 2), significantly higher than Comparative Example 1 (38.2%) and Comparative Example 3 (30.5%), and slightly higher than Comparative Example 2 (46.8%). This demonstrates that the multi-stage magnetic separation and high-frequency screening synergistic process of the present invention can effectively improve the grade of titanium concentrate.

[0138] 2. Titanium Recovery Rate: The titanium recovery rates of the processes of the present invention (Examples 1-5) were all ≥65.0%, with the highest reaching 68.5% (Example 2), significantly higher than those of Comparative Example 1 (42.5%), Comparative Example 2 (58.2%), and Comparative Example 3 (38.2%). This demonstrates that the process of the present invention is more effective in recovering titanium minerals of different particle sizes and can achieve efficient recovery of titanium minerals of all particle sizes.

[0139] 3. Energy Consumption: The energy consumption of the processes of the present invention (Examples 1-5) was ≤15.0 kWh / t, significantly lower than that of Comparative Example 1 (22.5 kWh / t) and Comparative Example 2 (28.5 kWh / t), and also lower than that of Comparative Example 3 (18.2 kWh / t). This is primarily due to the closed-loop control system and waste heat recovery device used in the processes of the present invention, which effectively reduce energy consumption.

[0140] 4. Environmental Performance: The present process (Examples 1-5) uses no chemical agents throughout the entire process, achieving a water recycling rate of ≥90%, superior to all comparative examples. In particular, compared to Comparative Example 2 (which used flotation agents), the present process avoids the environmental pollution risks associated with chemical agents.

[0141] 5. Product quality: The sulfur content of the titanium concentrate obtained by the process of the present invention is ≤0.10%, which is lower than that of all comparative examples and meets the requirements of downstream industrial applications.

[0142] In addition, the recovery effect of titanium minerals with different particle sizes was also tested, and the results are shown in Table 2.

[0143] Table 2 Recovery effect of titanium minerals with different particle sizes

[0144] Particle size range (mm) Example 2 Recovery (%) Comparative Example 1 Recovery (%) Comparative Example 2 Recovery (%) 0.1 60.2 35.8 45.3 0.074-0.1 72.5 48.6 62.8 0.038-0.074 75.8 50.2 65.5 -0.038 65.6 35.3 59.2 Comprehensive particle size 68.5 42.5 58.2

[0145] As can be seen from Table 2, the process of the present invention (using Example 2 as an example) exhibits good recovery effects for titanium minerals of all particle sizes, especially for the fine particle size (-0.038 mm), where the recovery rate is significantly higher than that of Comparative Examples 1 and 2. This is primarily due to the high-frequency screening and multi-stage magnetic separation synergistic system employed in the process of the present invention, as well as specialized treatment measures for fine-particle titanium minerals (such as the use of a hydrocyclone).

[0146] In addition, the resource utilization effect of tailings was tested. The results showed that the compressive strength of the unburned bricks made from the tailings produced by the process of the present invention after treatment was ≥15.0MPa, which met the application standards of building materials and achieved 100% resource utilization of tailings.

[0147] The process of the present invention has significant advantages over traditional technologies, and its core mechanism is mainly reflected in the following aspects:

[0148] 1. Magnetic Field Intensity Gradient Matching Principle: This invention utilizes a three-level gradient-decreasing magnetic field intensity (1.2-1.5T for primary magnetic separation, 0.8-1.0T for secondary magnetic separation, and 0.4-0.6T for dry magnetic separation) to precisely separate ilmenite and hematite based on their different magnetization characteristics. The primary high-intensity magnetic separation primarily removes weakly magnetic gangue, the secondary magnetic separation prioritizes the magnetic differences between ilmenite and gangue, and the dry magnetic separation precisely separates residual weakly magnetic minerals. This gradient design avoids the difficulty of achieving a balanced balance between selectivity and recovery with a single magnetic field intensity.

[0149] 2. High-frequency screening-ball milling closed-loop system synergy: In traditional processes, ball milling and screening are typically performed independently. However, this invention utilizes an online particle size analyzer to establish a closed-loop feedback mechanism, allowing real-time adjustment of ball mill parameters to avoid over- or under-grinding. This mechanism allows the oversize material (+0.1mm coarse particles) to be crushed and returned to the wet magnetic separation system, while the undersize material (-0.074mm fine particles) is purified through secondary magnetic separation, achieving efficient recovery of titanium minerals in the full 0.1-5mm particle size range.

[0150] 3. Principle of complementary advantages between wet and dry magnetic separation: Wet magnetic separation is beneficial for sorting fine-grained minerals, but pulp concentration significantly impacts the sorting effect; dry magnetic separation, on the other hand, has high requirements for the surface condition of the minerals, but offers excellent sorting accuracy. This invention organically combines the two, synergizing a wet magnetic separation system (gravity water separation + ball milling + secondary magnetic separation) with a dry magnetic separation system (drying + permanent magnetic roller separation) to deeply enrich fine-grained titanium minerals, fully leveraging the advantages of both magnetic separation processes.

[0151] 4. Surface cleaning technology: The surface of titanium minerals is susceptible to mud and charged particles, which can affect separation efficiency. This invention uses a high-pressure airflow nozzle (0.3-0.5 MPa) to remove fine mineral mud adsorbed on the mineral surface before dry magnetic separation. Furthermore, a tungsten carbide coating on the drum surface effectively avoids charge interference and mineral adhesion, significantly improving separation accuracy.

[0152] 5. Energy Recycling Mechanism: This invention utilizes concentrated water recycling technology (water recycling rate > 90%) and a waste heat recovery device (heat energy utilization rate > 80%) to establish an energy recycling system, significantly reducing energy consumption. In particular, the waste heat recovery device in the drying system uses the heat energy of the exhaust hot air to preheat the feed, reducing overall energy consumption per ton of ore by 35% compared to traditional processes.

[0153] In summary, the present invention realizes the efficient recovery and comprehensive utilization of titanium resources in iron ore tailings through the synergistic effect of multi-stage magnetic separation and high-frequency screening, combined with closed-loop control and energy recycling technology, and has significant technical advantages and economic and environmental benefits.

[0154] The process has been tested industrially at a concentrator affiliated with a steel group, processing 5 tons per hour. The results demonstrate that the process is stable in industrial applications, capable of enriching iron ore tailings with a TiO2 content of 5.5% into titanium concentrate with a TiO2 grade of 49.2%, achieving a recovery rate of 67.5% and an energy consumption of 14.5 kWh / t. These performance indicators outperform existing technologies.

[0155] Titanium concentrate products have been successfully applied to titanium dioxide production and titanium alloy smelting, achieving excellent economic benefits. Unfired bricks made from tailings have also passed building materials industry standard testing, achieving comprehensive resource utilization.

[0156] Economic benefit analysis shows that the process of this invention improves the economic benefits per ton of ore produced by treating iron ore tailings by approximately 35% compared to conventional processes, primarily due to increased titanium recovery and reduced energy consumption. Furthermore, this process avoids the use of chemical agents, reducing environmental pollution risks and delivering significant social benefits.

[0157] The physical separation process for enriching titanium concentrate from iron ore tailings, based on the synergy of multi-stage magnetic separation and high-frequency screening, provided by the present invention, achieves efficient recovery and utilization of titanium resources in iron ore tailings through rational process design and optimization of key equipment parameters. Compared with existing technologies, the present invention has the following significant advantages:

[0158] 1. The grade and recovery rate of titanium concentrate are significantly improved, with TiO2 grade ≥48% and recovery rate ≥65%;

[0159] 2. The overall energy consumption is greatly reduced, with the power consumption per ton of ore processed being ≤15kWh, which is 50% lower than that of the flotation process;

[0160] 3. Excellent environmental performance, no chemical agents are added throughout the process, and the wastewater recycling rate is ≥90%;

[0161] 4. The tailings have a high degree of resource utilization and can be used to produce unburned bricks with a compressive strength of ≥15MPa, achieving 100% resource utilization of tailings;

[0162] 5. It has strong adaptability and has good recovery effect on titanium minerals of all particle sizes from 0.1 to 5 mm.

[0163] Therefore, the process of the present invention not only solves the problems of low titanium resource recovery rate, high energy consumption, and high environmental pollution risk in iron ore tailings, but also realizes the comprehensive utilization of resources, with significant economic, social and environmental benefits.

[0164] The foregoing is merely an embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. A physical separation process for enriching titanium concentrate from iron ore tailings based on the synergy of multi-stage magnetic separation and high-frequency screening, characterized in that: The following steps are involved: (1) Raw material pretreatment: Mix the iron ore tailings with water in a mass ratio of 1:2 to 1:3, control the slurry concentration to 25% to 30%, adjust the pH value to 6.5 to 7.5, and use a stirring barrel with a speed of 80 to 120 rpm to evenly disperse the slurry. The stirring time is ≥ 10 min. (2) Single-stage flat plate strong magnetic separation: Use a vertical ring high gradient magnetic separator with a background magnetic field strength of 1.2 to 1.5 T, a separation gap of 5 to 8 mm, a magnetic medium of 2 mm diameter and 3 mm spacing of magnetic conductive stainless steel rods, a pulse frequency of ≥ 300 times / min, and a slurry flow rate of 1.0 to 1.5 m 3 / h, obtaining a titanium crude concentrate with a TiO2 grade of 15% to 18%; (3) High-frequency screening and grading: A double-layer high-frequency vibrating screen with a vibration frequency of 1800-2400 times / min and an amplitude of 2-4 mm is used. The upper screen hole is 0.1 mm and the lower screen hole is 0.074 mm. The material on the screen is returned to the ball mill for re-crushing. The ball filling rate of the ball mill is 30%-40%. The material under the screen enters the subsequent sorting process, of which the particle size of ≤0.074 mm accounts for ≥90%; (4) Gravity water separation and enhanced classification: Use a spiral chute with an inclination angle of 15° to 20° and a trough surface made of polyurethane, and the slurry flow rate is 0.8 to 1.2 m 3 / h; and cooperate with a hydrocyclone with an inlet pressure of 0.15-0.25MPa and a separation particle size of 10-25μm to obtain titanium ore with a TiO2 grade of ≥25% and a sulfur content of ≤0.3%; (5) Secondary flat plate high-intensity magnetic separation: A double-ring high-gradient magnetic separator with a magnetic field strength of 0.8 to 1.0 T is used. The magnetic medium is a composite magnetic block of neodymium iron boron and magnetic conductive stainless steel. The pulse frequency is 350 to 400 times / min. The slurry concentration is adjusted to 20% to 25%, and titanium ore with a TiO2 grade of 35% to 38% is obtained. (6) Dry magnetic separation of titanium middlings: Dry the titanium middlings at 80-100°C for 20-30 min, control the moisture content to ≤3%, and maintain the particle size of -200 mesh at ≥85% after drying; use a permanent magnetic drum dry magnetic separator with a magnetic field strength of 0.4-0.6T and a drum speed of 60-80rpm for final purification to obtain titanium concentrate with a TiO2 grade of ≥48%, a sulfur content of ≤0.1%, and a recovery rate of ≥65%.

2. The physical separation process for enriching titanium concentrate from iron ore tailings based on the coordination of multi-stage magnetic separation and high-frequency screening according to claim 1 is characterized in that: The high-frequency screening system and the ball milling system in step (3) constitute a closed-loop control system, which monitors the particle size of the material on the screen in real time through an online particle size analyzer, and automatically adjusts the ball mill speed to 15-25 rpm and the steel ball ratio, wherein the steel ball diameter is Φ30-50 mm, to ensure that the crushing efficiency is maximized and the over-grinding rate is ≤5%.

3. The physical separation process for enriching titanium concentrate from iron ore tailings based on the coordination of multi-stage magnetic separation and high-frequency screening according to claim 1 is characterized in that: In the gravity water separation stage of step (4), a flow stabilizer is added to control the slurry flow rate fluctuation to ≤±0.1m 3 / h, improving the sorting stability; at the same time, the tailings of the primary magnetic separation are subjected to secondary sorting in a spiral chute to recover the lost fine-grained ilmenite.

4. The physical separation process for enriching titanium concentrate from iron ore tailings based on the coordination of multi-stage magnetic separation and high-frequency screening according to claim 1 is characterized in that: A high-pressure airflow nozzle is added to the inlet of the dry magnetic separator in step (6) with a pressure of 0.3 to 0.5 MPa to remove fine mineral mud adsorbed on the surface of the mineral and avoid charge interference; at the same time, a tungsten carbide coating with a thickness of 50 to 100 μm is used on the surface of the drum to reduce mineral adhesion.

5. The physical separation process for enriching titanium concentrate from iron ore tailings based on the coordination of multi-stage magnetic separation and high-frequency screening according to claim 1 is characterized in that: The magnetic field intensity of each stage of magnetic separation decreases gradually, with the primary magnetic separation being 1.2-1.5T, the secondary magnetic separation being 0.8-1.0T, and the dry magnetic separation being 0.4-0.6T, thus forming a selective separation for different magnetic minerals.

6. The physical separation process for enriching titanium concentrate from iron ore tailings based on the coordination of multi-stage magnetic separation and high-frequency screening according to claim 1 is characterized in that: The hydrocyclone in step (4) can effectively recover -25 μm fine-particle titanium minerals by controlling the inlet pressure to 0.15-0.25 MPa.

7. The physical separation process for enriching titanium concentrate from iron ore tailings based on the coordination of multi-stage magnetic separation and high-frequency screening according to claim 1 is characterized in that: After the high-frequency screening in step (3) is completed, the gravity water separation tailings are put into the high-frequency screen for classification for the second time, and the classification requirements are the same as those in step (3).

8. The physical separation process for enriching titanium concentrate from iron ore tailings based on the coordination of multi-stage magnetic separation and high-frequency screening according to claim 1 is characterized in that: The drying system in step (6) adopts a waste heat recovery device, and the heat energy utilization rate is ≥80%, thereby reducing energy consumption.

9. The physical separation process for enriching titanium concentrate from iron ore tailings based on the coordination of multi-stage magnetic separation and high-frequency screening according to claim 1, characterized in that: No chemical agents are added throughout the process. After the process wastewater is treated in the sedimentation tank, the suspended solids content is ≤50mg / L and the reuse rate is ≥90%.

10. The physical separation process for enriching titanium concentrate from iron ore tailings based on the coordination of multi-stage magnetic separation and high-frequency screening according to claim 1, characterized in that: The sorted tailings in the process are finely ground to -25μm with a proportion of ≥80%, mixed with cement at a mass ratio of 1:3, and pressed into unfired bricks with a compressive strength of ≥15MPa, thereby realizing resource utilization of the tailings.

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