Titanium ore recovery method and belt magnetic separation device in titanium dioxide production

Abstract

The application discloses a belt magnetic separation device in titanium dioxide production and a titanium ore recovery method, and relates to the technical field of titanium dioxide production waste residue resource utilization, and comprises the following steps: S1, pretreating the sludge generated in an acidolysis process, wherein the pretreatment comprises screening, washing and drying; S2, uniformly feeding the pretreated sludge into the belt magnetic separation device, and separating titanium-containing minerals by using a magnetic field; S3, performing pickling treatment on the titanium-containing minerals after magnetic separation, and removing residual impurities; and S4, drying and crushing the titanium-containing minerals after pickling, and obtaining a high-purity titanium ore product. Through a rotating motor and stirring fan blades, the feeding device can continuously disperse the sludge in the feeding device after feeding, so that the sludge cannot be accumulated at the feeding port. The continuous dispersion effect of the stirring blades can destroy the agglomeration structure of the sludge, so that the sludge can be kept in a loose and flowing state, and the material can be uniformly and stably fed into the magnetic separation system.

Description

Technical Field

[0001] This invention relates to the field of resource utilization technology for waste residue from titanium dioxide production, and particularly to a belt magnetic separator and titanium ore recovery method used in titanium dioxide production. Background Technology

[0002] Titanium dioxide, the world's largest-produced white pigment, is widely used in coatings, plastics, papermaking, and other industries. The resource utilization of waste generated during its production is a key link in achieving environmental protection and a circular economy. Titanium ore recovery technology focuses on the deep treatment of byproducts such as sludge and titanium gypsum from the acidolysis process. Through physical sorting, chemical purification, and comprehensive utilization, it achieves efficient recovery and high-value utilization of titanium resources. In the sulfuric acid process for titanium dioxide production, ilmenite, after acidolysis and sedimentation, produces titanium-containing sludge, mainly composed of unreacted ilmenite, silicates, iron oxides, and sulfates.

[0003] Existing titanium ore recovery methods typically employ belt magnetic separators using a permanent magnet-electromagnetic composite magnetic field, combined with a high-frequency pulsed magnetic field, to separate weakly magnetic ilmenite from strongly magnetic impurities. However, excessive titanium sludge entering the feed inlet during feeding can cause blockages. This excessive material buildup leads to overload on transmission components such as the conveyor belt, motor, and reducer, causing bearing overheating, belt slippage, and motor burnout. Furthermore, the blockage exerts continuous compressive stress on the feed hopper and guide plates, potentially causing cracks in the steel plate welds and accelerated wear of the anti-slip texture.

[0004] There are already relevant invention patents concerning titanium ore recovery, as detailed below:

[0005] Chinese Patent Application No.: 202010655635.0, invention patent title: A titanium ore recycling process. This invention discloses a titanium ore recycling process, including the following steps: (1) leaching the raw ore with sulfuric acid in two stages to obtain a first-stage leaching solution and a second-stage leaching residue; (2) adding ammonium sulfate to the first-stage leaching solution so that the aluminum sulfate in the first-stage leaching solution reacts with the ammonium sulfate to generate aluminum ammonium sulfate, and the aluminum ammonium sulfate in the solution crystallizes out; (3) extracting and hydrolyzing the tail liquid after the aluminum ammonium sulfate crystallization to prepare titanium dioxide; (4) heating and concentrating the extraction waste acid and filtering it to obtain a sulfuric acid concentrate of a certain concentration and iron sulfate crystals of a certain yield, and returning the sulfuric acid concentrate to the first-stage leaching. This invention can realize the comprehensive recycling of the main elements titanium, iron, silicon and aluminum in the ore, and the recycling rate of each element can reach more than 77%, which points the way for the mine to achieve clean production and utilization without tailings and wastewater discharge and improve the economic value of the mine.

[0006] However, while the aforementioned existing patents can achieve clean production and utilization with no tailings or wastewater discharge, they still fail to solve the problem of blockage at the feed inlet of the belt magnetic separator. Excessive accumulation of titanium sludge causes a sudden increase in conveyor belt tension, leading to motor stalling and gear breakage in the reducer. Moreover, the organic matter remaining in the titanium sludge may spontaneously combust at high temperatures, and when blockage causes the local temperature to rise above 200°C, the probability of dust explosion increases eightfold. Summary of the Invention

[0007] The purpose of this application is to provide a belt magnetic separator and a titanium ore recovery method for titanium dioxide production, in order to solve the problem of potential blockage at the feed inlet of existing belt magnetic separators.

[0008] This invention efficiently recovers titanium ore resources from sludge through pretreatment, belt magnetic separation, and acid washing, thereby reducing resource waste and environmental pollution.

[0009] A method for recovering titanium ore in titanium dioxide production specifically includes the following steps:

[0010] S1, pre-treat the sludge produced in the acid hydrolysis process, including screening, washing and drying;

[0011] S2, the pretreated sludge is evenly fed into a belt magnetic separator to separate titanium-containing minerals using a magnetic field.

[0012] S3, acid washing is performed on the titanium-containing minerals after magnetic separation to remove residual impurities;

[0013] S4 involves drying and pulverizing the acid-washed titanium-containing minerals to obtain high-purity titanium ore products.

[0014] As a further improvement of the present invention, in step S1, the screening is carried out by a vibrating screen with a three-layer screening frequency of 28-32Hz. The mud is crushed to <2mm and then enters the screening system. The mud particles >0.5mm are returned to the crusher for recycling. The mud particles of 0.1-0.5mm are qualified and enter the washing process. The washing is carried out by a three-stage countercurrent washing tower with a liquid-to-solid ratio of 6:1. In the first stage of the three-stage countercurrent washing tower, 5% lime milk is added to neutralize the acidity. In the second stage of the three-stage countercurrent washing tower, pure water is used to wash until the conductivity is <100μS / cm. In the third stage of the countercurrent washing tower, deionized water is used for rinsing. The washing temperature is 40-50℃ and the stirring speed is 150rpm. The washing time for each stage is 30 minutes. The drying is carried out by a paddle dryer with the hot air temperature controlled at 120-140℃. The washed mud is left to stand for 45-60 minutes. A three-layer screening process using a 28-32Hz high-frequency vibrating screen, combined with pre-crushing of sludge to <2mm, ensures that particles >0.5mm are returned to the crusher for recycling, while qualified particles of 0.1-0.5mm enter the washing process. This design achieves a screening efficiency of ≥95%, increases the dissociation degree of titanium minerals to over 85%, reduces titanium loss from coarse particles, and improves titanium recovery rate by 5%-8%. The vibration frequency is optimized to 28-32Hz, ensuring screening efficiency while avoiding equipment wear caused by high-frequency vibration or screen clogging caused by low-frequency vibration.

[0015] As a further improvement of the present invention, in step S2, the magnetic field separation adopts a PLC system. The PLC system monitors the material thickness on the conveyor belt, the magnetic field strength distribution, and the separation effect in real time. The PLC system detects the weak magnetic separation section for separating strongly magnetic minerals, and the PLC system detects the strong magnetic separation section for recovering ilmenite. By monitoring the material thickness in real time through the PLC system, the conveyor belt speed and magnetic field strength are automatically adjusted to ensure that the weak magnetic section efficiently separates strongly magnetic impurities such as magnetite, and the strong magnetic section accurately enriches ilmenite. Combined with the 0.1-0.5mm qualified particle size characteristic of the screening stage, the PLC system can dynamically match the magnetic field gradient and material flow rate, enabling the efficient capture of fine ilmenite particles in the strong magnetic section and reducing the loss of fine-particle titanium.

[0016] As a further improvement of the present invention, in step S3, the pickling is carried out in a pickling tank, which is lined with fiberglass and made of titanium alloy. The pickling treatment uses dilute sulfuric acid with a concentration of 8-12%, the temperature of the pickling tank is controlled at 60-70℃, the stirring speed during pickling is 200-250 rpm, and the pickling time is 60-90 minutes. During the pickling process, the pH value and titanium ion concentration are continuously monitored. The waste sulfuric acid after pickling is subjected to three-stage sedimentation and plate and frame filtration. After sedimentation and filtration, the acid solution enters the evaporation and concentration system. The evaporation and concentration acid solution is concentrated to 30% of its original volume and then reused. The inner wall of the pickling tank is lined with fiberglass and the outer layer is made of titanium alloy, forming a double corrosion-resistant barrier. Fiberglass is resistant to strong acids such as sulfuric acid and hydrochloric acid, and titanium alloy has excellent corrosion resistance in oxidizing acids. The combination of the two extends the service life of the pickling tank to more than three times that of traditional carbon steel equipment, reducing the frequency of downtime and maintenance due to corrosion.

[0017] As a further improvement of the present invention, in step S4, the drying process employs an airflow dryer, with the hot air temperature of the airflow dryer controlled at 150-180℃, and the pulverization process employs an ultrafine pulverizer. Compared to traditional paddle dryers, the airflow dryer increases thermal efficiency by 30% and reduces energy consumption per unit product by 20%. High-temperature hot air directly contacts the material, reducing heat loss, and the hot air can be recycled. Furthermore, the ultrafine pulverizer achieves continuous production through high-frequency impact and graded synergy, resulting in improved pulverization efficiency compared to traditional ball mills.

[0018] As a further improvement of the present invention, the three-stage sedimentation involves first injecting the waste acid after pickling into a sedimentation tank, where large solid impurities are separated by gravity sedimentation. The sedimentation time in the sedimentation tank is ≥2 hours. The upper clear liquid is further filtered by a plate and frame filter press. Sodium sulfide is added to the filtered clear liquid, which is used to form insoluble sulfide precipitates with the heavy metals in the clear liquid. After precipitation, the heavy metal content is reduced by pressure filtration. The treated clear liquid is then injected into a vacuum evaporator, where the acid volume is reduced to 30%-40% of its original volume through low-temperature evaporation. The evaporation uses indirect heating with steam to avoid direct contact between the acid and the heat source. After the concentrated acid is cooled to below 40°C, the acid concentration and impurity content are tested. The qualified acid is returned to the pickling process for recycling. Through a three-stage sedimentation and supporting treatment process, a closed-loop system of "solid-liquid separation - chemical precipitation - evaporation concentration - recycling" is implemented, achieving deep removal of heavy metals, zero waste discharge, efficient recycling of acid, energy saving and consumption reduction, and equipment corrosion protection upgrades. At the same time, PLC automation control is combined to improve process stability.

[0019] A belt magnetic separator for titanium dioxide production includes a feeding device for uniformly distributing and conveying pretreated sludge to a magnetic separation zone. The feeding device includes a discharge port, and a conveyor belt is positioned on one side of the discharge port to carry the sludge through the magnetic separation zone. A permanent magnet plate is positioned below the conveyor belt to generate a high-intensity magnetic field to separate titanium-containing minerals. An electromagnetic separation device is positioned above the conveyor belt to further separate weakly magnetic titanium-containing minerals. A discharge device is positioned on the side of the conveyor belt away from the feeding device to collect both magnetic and non-magnetic impurities containing titanium ore.

[0020] As a further improvement of the present invention, the feeding device adopts a screw feeder + vibrating distributor, the conveyor belt is made of polyurethane corrosion-resistant material, the surface of the conveyor belt is engraved with diamond anti-slip texture, the permanent magnet plate is made of neodymium iron boron material, the magnetic field strength of the permanent magnet plate is continuously adjustable from 0.5-2.0T, the electromagnetic separation device adopts a high-frequency pulse power supply, the peak magnetic field strength of the high-frequency pulse power supply can reach 3.0T, and the high-frequency pulse power supply is used to capture weakly magnetic ilmenite.

[0021] As a further improvement of the present invention, a base plate is fixedly connected to the bottom end of the feeding device, a protective frame is fixedly connected to the bottom end of the base plate, a rotary motor is provided inside the bottom end of the protective frame, a connecting rod is fixedly connected to the output end of the rotary motor, a plurality of stirring blades are fixedly connected to the outer surface of the connecting rod, an anti-collision slider is fixedly connected to the top end of the connecting rod, a connecting wire is provided at the bottom end of the rotary motor, the rotary motor and the connecting wire are connected for signal connection, the end of the connecting wire away from the rotary motor is connected for signal connection to a start switch, a funnel inlet is fixedly connected to the top end of the anti-collision slider, and a millimeter-level through-hole is provided through the top end of the funnel inlet.

[0022] Compared with the prior art, the beneficial effects of this invention are as follows:

[0023] 1. The rotating motor and agitator blades continuously disperse the sludge within the feeding device after it has been fed in, preventing sludge accumulation at the inlet. Sludge accumulation at the inlet obstructs material flow, leading to equipment shutdown or uneven feeding. The continuous dispersing action of the agitator blades breaks down the agglomerated structure of the sludge, keeping it loose and flowing, ensuring that the material enters the magnetic separation system uniformly and stably.

[0024] 2. By employing a three-stage sedimentation and plate-and-frame filtration process, the acid solution after sedimentation and filtration enters the evaporation and concentration system. The concentrated acid solution is then concentrated to 30% of its original volume for reuse. This reuse of concentrated acid solution can replace the purchase of some fresh acid solution, directly reducing raw material costs. Furthermore, the concentration process allows for precise control of the acid concentration, ensuring that the acid performance is consistent with that of fresh acid solution during reuse, thus avoiding process instability caused by concentration fluctuations.

[0025] 3. The addition of sodium sulfide can target and remove heavy metals from the clarified liquid, forming insoluble sulfide precipitates. Sulfide precipitates are less sensitive to pH and, compared to hydroxide precipitates, can adapt to fluctuations in the pH of the waste liquid, preventing the redissolution of heavy metals due to pH imbalance. Sodium sulfide reacts with heavy metals in the acid solution to form sulfide precipitates with extremely low Ksp, reducing the heavy metal concentration to below 0.01 mg / L, thus ensuring that the acid solution meets the impurity requirements of the pickling process.

[0026] 4. The PLC system monitors material thickness in real time and automatically adjusts conveyor belt speed and magnetic field strength to ensure efficient separation of strongly magnetic impurities such as magnetite in the weak magnetic section and precise enrichment of ilmenite in the strong magnetic section. Low magnetic field strength and slow conveying ensure complete adsorption of magnetite, while intergrowths or gangue are discharged due to their weak magnetism.

[0027] 5. Due to the potential adhesion of washed and dried sludge through the funnel inlet and millimeter-level through-hole, the sludge entering the feeding device may be too large, causing blockage at the outlet. By rotating the funnel inlet in advance, the millimeter-level through-hole at its top is activated for filtration. The centrifugal force generated during rotation throws larger, easily adhering sludge particles against the inner wall of the funnel, preventing them from directly entering the feeding device. Furthermore, during rotation, the sludge generates shear forces against the edge of the through-hole and the inner wall of the funnel, which can break down the agglomerate structure of the dried sludge. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the steps of the present invention.

[0030] Figure 2 This is a three-dimensional structural diagram of the belt magnetic separator in this invention.

[0031] Figure 3 For the present invention Figure 2 A schematic diagram of the three-dimensional structure at point A in the middle.

[0032] Figure 4 This is a three-dimensional structural diagram of the feeding device and the anti-collision slider in this invention.

[0033] Figure 5 This is a three-dimensional structural diagram of the funnel inlet and the millimeter-level through-hole in this invention.

[0034] Figure 6 This is a three-dimensional structural diagram of the protective frame, stirring blades, and anti-collision slider in this invention.

[0035] Figure 7 This is a three-dimensional structural diagram of the rotary motor, connecting wires, and starter switch in this invention.

[0036] In the diagram: 101, hopper inlet; 102, millimeter-level through-hole; 201, feeding device; 202, discharge port; 203, bottom plate; 204, protective frame; 205, rotary motor; 206, connecting rod; 207, stirring blade; 208, anti-collision slider; 209, connecting wire; 210, start switch. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] A belt magnetic separator and a method for recovering titanium ore in titanium dioxide production, such as Figure 1-7 As shown, it includes the following steps:

[0039] S1. The sludge generated from the acid hydrolysis process is pretreated, including screening, washing, and drying. Screening is performed using a three-layer vibrating screen with a vibration frequency of 28-32Hz. Sludge particles crushed to <2mm enter the screening system. Particles >0.5mm are returned to the crusher for recycling. Sludge particles of 0.1-0.5mm are considered qualified and enter the washing process. Washing is performed using a three-stage countercurrent washing tower with a liquid-to-solid ratio of 6:1. In the first stage of the three-stage countercurrent washing tower, 5% lime milk is added to neutralize the acidity. In the second stage, pure water is used for washing until the conductivity is <100μS / cm. In the third stage, deionized water is used for rinsing. The washing temperature is 40-50℃, the stirring speed is 150rpm, and the washing time for each stage is 30 minutes. Drying is performed using a paddle dryer with the hot air temperature controlled at 120-140℃. The washed sludge is left to stand for 45-60 minutes. The vibrating screen employs a three-layer screening and circulating crushing mechanism, achieving precise separation of qualified particle sizes from 0.1 to 0.5 mm through three-layer screening. This grading control ensures uniform particle size of the material entering the magnetic separator, reducing separation deviations caused by particle size differences and improving the recovery rate of ilmenite. The three-stage countercurrent washing provides deep purification. The first stage adds 5% lime milk to neutralize the acidity, effectively removing acidic impurities such as sulfate and iron ions from the sludge and reducing the risk of corrosion in subsequent processes. The second stage uses pure water washing until the conductivity is <100μS / cm, ensuring deep removal of soluble impurities such as salts and heavy metals. The third stage uses deionized water rinsing to further purify the material and reduce interference from impurities on the magnetic field during magnetic separation.

[0040] Example 1 compares the advantages of the present invention under the following conditions: sieving process, washing process, drying parameters, magnetic separation control, acid washing cycle, and drying and pulverizing. A detailed comparison table is shown below:

[0041] Table 1 Comparison of Refined, Intelligent, and Efficient Titanium Ore Recovery

[0042]

[0043] Based on Table 1 above, it can be concluded that the three-layer screening and circulating crushing mechanism can ensure uniform particle size of the material entering the magnetic separation, reduce separation deviation, and increase the recovery rate of ilmenite from the traditional 70%-75% to 82%-85%. The PLC dynamic magnetic separation system, through real-time monitoring and adaptive adjustment, reduces the loss rate of magnetite tailings in the weak magnetic section from 8% to 3%, and increases the recovery rate of ilmenite in the strong magnetic section from 75% to 85%. The three-stage countercurrent washing, through lime slurry neutralization, pure water washing to a conductivity of <100μS / cm, and deionized water rinsing, increases the TiO2 content of titanium concentrate from 85% to over 92%, and reduces the impurity content (such as Fe2O3) from 3% to below 1%, meeting the requirements for high-end titanium dioxide production.

[0044] S2, the pretreated sludge is uniformly fed into a belt magnetic separator, where titanium-containing minerals are separated using a magnetic field. The magnetic separation employs a PLC system, which monitors the material thickness on the conveyor belt, the magnetic field strength distribution, and the separation effect in real time. The PLC system detects weak magnetic separation sections that separate strongly magnetic minerals, and strong magnetic separation sections used for recovering ilmenite. The belt magnetic separator includes a feeding device 201, which uniformly distributes and conveys the pretreated sludge to the magnetic separation area. The feeding device 201 includes a discharge port 202. A conveyor belt is located on one side of the feeding device 201 at the discharge port 202, carrying the sludge and guiding it through the magnetic separation area. A permanent magnet plate is positioned below the conveyor belt to generate a high-intensity magnetic field for separating titanium-containing minerals. An electromagnetic separation device is positioned above the conveyor belt to further separate weakly magnetic titanium-containing minerals. A discharge device is located on the side of the conveyor belt away from the feeding device 201, collecting both magnetic materials and non-magnetic impurities containing titanium ore. The PLC system monitors the material thickness and magnetic field strength distribution on the conveyor belt in real time, automatically adjusting the magnetic field strength of the permanent magnet plate in the weak magnetic separation section and the conveyor belt speed to ensure that the magnetite is completely adsorbed. The PLC system collects material thickness, magnetic field strength, and separation effect data 10-20 times per second. When the thickness fluctuation exceeds the threshold, it automatically adjusts the conveyor belt speed or magnetic field strength to ensure that the separation parameters always match the material characteristics and reduce the risk of overload or underload.

[0045] Example 2 compares the advantages of the present invention in detail, using dynamic magnetic field control, corrosion-resistant conveyor belt design, gradient magnetic field coordination, and intelligent monitoring as comparative conditions. The specific comparison table is as follows:

[0046] Table 2 Comparison of Titanium Ore Sorting Efficiency Improvements

[0047]

[0048] Based on Table 2 above, it can be concluded that dynamic magnetic field control and uniform feeding increased the recovery rate of ilmenite from 70%-75% to 82%-85%, reduced the loss rate of magnetite tailings from 8% to 3%, and increased the TiO2 content of concentrate from 45% to 52%. Furthermore, the polyurethane conveyor belt and optimized magnetic field parameters reduced unit energy consumption from 12-15 kWh / t to 8-10 kWh / t, resulting in annual electricity savings exceeding one million yuan.

[0049] The feeding device 201 adopts a screw feeder + vibrating distributor. The conveyor belt is made of polyurethane corrosion-resistant material, and the surface of the conveyor belt is engraved with diamond anti-slip texture. The permanent magnet plate is made of neodymium iron boron material, and the magnetic field strength of the permanent magnet plate is continuously adjustable from 0.5-2.0T. The electromagnetic separation device adopts a high-frequency pulse power supply, and the peak magnetic field strength of the high-frequency pulse power supply can reach 3.0T. The high-frequency pulse power supply is used to capture weakly magnetic ilmenite. A base plate 203 is fixedly connected to the bottom of the feeding device 201. A protective frame 204 is fixedly connected to the bottom of the base plate 204. A rotary motor 205 is installed inside the bottom of the protective frame 204. A connecting rod 206 is fixedly connected to the output end of the rotary motor 205. Several stirring blades 207 are fixedly connected to the outer surface of the connecting rod 206. An anti-collision slider 208 is fixedly connected to the top of the connecting rod 206. A connecting line 209 is installed at the bottom of the rotary motor 205. The rotary motor 205 and the connecting line 209 are connected by a signal. The end of the connecting line 209 away from the rotary motor 205 is connected to a start switch 210. A funnel inlet 101 is fixedly connected to the top of the anti-collision slider 208. A millimeter-level through-hole 102 is opened through the top of the funnel inlet 101. The combination of a screw feeder and a vibrating distributor enables continuous and quantitative feeding via the screw feeder, preventing material accumulation or flow interruption. The vibrating distributor uses high-frequency vibration to evenly spread the material on the conveyor belt, ensuring consistent thickness and reducing sorting deviations caused by uneven material distribution. A dual "pre-screening-anti-clogging" mechanism is formed by the hopper inlet 101 and the millimeter-sized through-hole 102, which, in conjunction with the agitator blades 207 driven by the rotary motor 205. When the agitator blades 207 rotate, the anti-collision slider 208 buffers material impact, preventing blockage of the millimeter-sized through-hole 102. The millimeter-sized aperture only allows qualified particle size to enter; coarse particles are intercepted and returned to pre-treatment via a bypass, reducing the load on subsequent magnetic separation and improving sorting accuracy.

[0050] Example 3 compares the advantages of the present invention in detail, using feed control, magnetic field system, anti-clogging mechanism, and diversion accuracy as comparative criteria. The specific comparison table is as follows:

[0051] Table 3 Comparison of Belt Magnetic Separation Mechanisms for Titanium Ore

[0052]

[0053] Based on Table 3 above, it can be concluded that dynamic magnetic field control and uniform feeding increased the recovery rate of ilmenite from 75% to 85%, reduced the loss rate of magnetite tailings from 8% to 3%, and increased the TiO2 content of concentrate to over 52%, thereby meeting the demand for high-end titanium dioxide.

[0054] S3 involves acid rinsing the titanium-containing minerals after magnetic separation to remove residual impurities. The acid rinsing is performed in an acid rinsing tank lined with fiberglass and made of titanium alloy. An 8-12% concentration of dilute sulfuric acid is used, with the tank temperature controlled at 60-70℃. The stirring speed during acid rinsing is 200-250 rpm, and the rinsing time is 60-90 minutes. The pH value and titanium ion concentration are continuously monitored during the acid rinsing process. The waste sulfuric acid after acid rinsing undergoes three-stage sedimentation and plate-and-frame filtration. After sedimentation and filtration, the acid solution enters an evaporation and concentration system. The concentrated acid solution is then reused after being concentrated to 30% of its original volume. Using 8-12% dilute sulfuric acid at 60-70℃ for 60-90 minutes effectively dissolves iron, manganese, and other metal oxides and silicate impurities on the surface of the titanium-containing minerals after magnetic separation. Continuous monitoring of the pH value and titanium ion concentration allows for real-time adjustment of the acid rinsing time or replenishment of acid, preventing over-rinsing leading to titanium dissolution loss or insufficient acid resulting in impurity residue. Suspended solids in the pickling solution are removed through three-stage sedimentation, and further dewatered by plate and frame filter press, yielding a clear acid solution. This treatment reduces the solid impurity content in the acid solution from 5% to below 0.5%, meeting the requirements for recycling.

[0055] Example 4 compares the advantages of the present invention in detail, using precise control of pickling parameters, corrosion-resistant equipment design, and waste acid recycling as comparative conditions. The specific comparison table is as follows:

[0056] Table 4 Comparison of Precise Control of Acid Laying Parameters in Titanium Ore

[0057]

[0058] Table 4 above concludes that precise acid concentration and temperature control increase the TiO2 content of titanium concentrate from 85% to over 92%, and reduce the impurity content from 3% to below 1%, thus meeting the requirements for high-end titanium dioxide production. Real-time monitoring of pH and titanium ion concentration, and dynamic adjustment of pickling parameters, prevents titanium dissolution and loss due to over-pickling. Furthermore, the fiberglass lining and titanium alloy pickling tank offer strong corrosion resistance, extending the equipment's lifespan from 3-5 years to 8-10 years.

[0059] The three-stage sedimentation process involves first injecting the waste acid from pickling into a sedimentation tank. Large solid particles are separated by gravity sedimentation in the tank, with a sedimentation time of at least 2 hours. The supernatant is then further filtered by a plate and frame filter press. Sodium sulfide is added to the filtered supernatant to form insoluble sulfide precipitates with heavy metals in the supernatant. After precipitation, the heavy metal content is further reduced by filter press separation. The treated supernatant is then injected into a vacuum evaporator, where low-temperature evaporation reduces the acid volume to 30%-40% of its original volume. Evaporation uses indirect steam heating to avoid direct contact between the acid and the heat source. The concentrated acid is cooled to below 40°C, and the acid concentration and impurity content are tested. Qualified acid is returned to the pickling process for recycling. This three-stage sedimentation process ensures thorough purification of large solid particles (>50μm) through a gravity sedimentation time of at least 2 hours, reducing the solid content of the supernatant from 5% to below 1%. This reduces the load on subsequent plate and frame filter presses and extends the service life of the filter cloth. The fine filtration by plate and frame filter press further removes fine particles with a diameter of 1-50μm from the clear liquid through a pressure of 0.6-0.8MPa. The moisture content of the filter cake is ≤25%, resulting in a clear acid liquid that meets the requirements for subsequent heavy metal precipitation and evaporation concentration.

[0060] Example 5 compares the advantages of the present invention under the following conditions: three-stage sedimentation deep purification, optimized fine filtration pressure, high-efficiency sodium sulfide precipitation, and low-temperature evaporation circulation. A detailed comparison table is shown below:

[0061] Table 5 Comparison of Precise Control of Acid Laying Parameters in Titanium Ore

[0062]

[0063] Based on Table 5 above, it can be concluded that three-stage sedimentation + fine filtration reduces the solid impurity content of the acid solution from 5% to below 0.5%, and increases the heavy metal removal rate from 70% to 98%. Low-temperature evaporation avoids sulfuric acid decomposition, keeping the concentrated acid solution concentration stable at 24-36%, allowing for direct reuse and reducing the consumption of fresh acid.

[0064] S4 involves drying and pulverizing the acid-washed titanium-containing minerals to obtain high-purity titanium ore products. Drying is performed using an airflow dryer, with the hot air temperature controlled at 150-180℃. Pulverization is done using an ultrafine pulverizer. The airflow dryer utilizes high-speed hot air in parallel flow with the wet material, achieving rapid moisture evaporation through intense convection heat transfer, reducing drying time to several seconds to tens of seconds, increasing efficiency by 3-5 times compared to traditional paddle dryers. The ultrafine pulverizer mechanically pulverizes the titanium ore to micron or even submicron levels, significantly increasing the product's specific surface area. Increased specific surface area enhances the reactivity of the titanium ore in subsequent applications, improving production efficiency and product quality.

[0065] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for recovering titanium ore in titanium dioxide production, characterized in that, Specifically, the steps include the following: S1. The sludge generated from the acid hydrolysis process is pretreated, including screening, washing, and drying. Screening is performed using a three-layer vibrating screen with a vibration frequency of 28-32Hz. The sludge is crushed to <2mm and then enters the screening system. Particles >0.5mm are returned to the crusher for recycling. Sludge particles of 0.1-0.5mm are considered acceptable and enter the washing process. Washing is performed using a three-stage countercurrent washing tower with a liquid-to-solid ratio of 6:

1. The first stage of the washing tower adds 5% lime milk to neutralize the acidity. The second stage of the three-stage countercurrent washing tower uses pure water to wash until the conductivity is <100μS / cm. The third stage of the countercurrent washing tower uses deionized water for rinsing. The washing temperature is 40-50℃, the stirring speed during washing is 150rpm, and the washing time for each stage is 30 minutes. The drying is carried out using a paddle dryer, and the hot air temperature of the paddle dryer is controlled at 120-140℃. The washed sludge is left to stand for 45-60 minutes. S2, the pretreated sludge is evenly fed into a belt magnetic separator to separate titanium-containing minerals using a magnetic field. S3. The titanium-containing minerals after magnetic separation are acid-washed to remove residual impurities. The acid washing is performed in an acid washing tank lined with fiberglass and made of titanium alloy. The acid washing uses 8-12% dilute sulfuric acid. The temperature of the acid washing tank is controlled at 60-70℃. The stirring speed during acid washing is 200-250 rpm, and the acid washing time is 60-90 minutes. The pH value and titanium ion concentration are continuously monitored during the acid washing process. The waste sulfuric acid after acid washing undergoes three-stage sedimentation and plate and frame filtration. After sedimentation and filtration, the acid solution enters an evaporation and concentration system. The evaporated and concentrated acid solution is concentrated to 30% of its original volume for reuse. The three-stage sedimentation first... The solution is injected into a settling tank, where large solid particles are separated by gravity settling. The settling time in the settling tank is ≥2 hours. The supernatant is further filtered by a plate and frame filter press. Sodium sulfide is added to the filtered solution to form insoluble sulfide precipitates with the heavy metals in the solution. After precipitation, the heavy metal content is reduced by filter press separation. The treated solution is then injected into a vacuum evaporator, where the acid volume is reduced to 30%-40% of the original volume through low-temperature evaporation. The evaporation uses indirect steam heating to avoid direct contact between the acid and the heat source. After the concentrated acid is cooled to below 40°C, the acid concentration and impurity content are tested. Qualified acid is returned to the pickling process for recycling. S4 involves drying and pulverizing the acid-washed titanium-containing minerals to obtain high-purity titanium ore products.

2. The method for recovering titanium ore in titanium dioxide production as described in claim 1, characterized in that: In step S2, the magnetic field separation adopts a PLC system. The PLC system monitors the material thickness on the conveyor belt, the magnetic field strength distribution, and the separation effect in real time. The PLC system detects a weak magnetic separation section to separate strong magnetic minerals, and the PLC system detects a strong magnetic separation section for recovering ilmenite.

3. The method for recovering titanium ore in titanium dioxide production as described in claim 1, characterized in that: In step S4, the drying is performed using an airflow dryer, and the hot air temperature of the airflow dryer is controlled at 150-180℃. The pulverization is performed using an ultrafine pulverizer.

4. A belt magnetic separator for titanium ore recovery in titanium dioxide production as described in claim 1, characterized in that, The belt magnetic separator includes a feeding device (201) for uniformly distributing and conveying pretreated sludge to the magnetic separation area. The feeding device (201) includes a discharge port (202). A conveyor belt is provided on one side of the feeding device (201) and the conveyor belt is used to carry the sludge and make it pass through the magnetic separation area. A permanent magnet plate is provided below the conveyor belt and the permanent magnet plate is used to generate a high-intensity magnetic field to separate titanium-containing minerals. An electromagnetic separation device is provided above the conveyor belt and the electromagnetic separation device is used to further separate the weaker titanium-containing minerals. A discharge device is provided on the side of the conveyor belt away from the feeding device (201) and the discharge device is used to collect the magnetic materials and non-magnetic impurities of titanium-containing minerals respectively.

5. The belt magnetic separator in the titanium ore recovery method for titanium dioxide production as described in claim 4, characterized in that: The feeding device (201) adopts a screw feeder and a vibrating distributor. The conveyor belt is made of polyurethane corrosion-resistant material. The surface of the conveyor belt is engraved with diamond-shaped anti-slip patterns. The permanent magnet plate is made of neodymium iron boron material. The magnetic field strength of the permanent magnet plate is continuously adjustable from 0.5 to 2.0T. The electromagnetic separation device adopts a high-frequency pulse power supply. The peak magnetic field strength of the high-frequency pulse power supply can reach 3.0T. The high-frequency pulse power supply is used to capture weakly magnetic ilmenite.

6. The belt magnetic separator in the titanium ore recovery method for titanium dioxide production as described in claim 5, characterized in that: The bottom end of the feeding device (201) is fixedly connected to a base plate (203), and the bottom end of the base plate (203) is fixedly connected to a protective frame (204). The bottom end of the protective frame (204) is provided with a rotary motor (205). The output end of the rotary motor (205) is fixedly connected to a connecting rod (206). Several stirring blades (207) are fixedly connected to the outer surface of the connecting rod (206). The top end of the connecting rod (206) is fixedly connected to an anti-collision slider (208). The bottom end of the rotary motor (205) is provided with a connecting line (209). The rotary motor (205) and the connecting line (209) are connected by a signal. The end of the connecting line (209) away from the rotary motor (205) is connected to a start switch (210). The top end of the anti-collision slider (208) is fixedly connected to a funnel inlet (101). The top end of the funnel inlet (101) is provided with a millimeter-level through-hole (102).

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