A method for preparing high-purity silica from copper metallurgical tailings

Abstract

This invention discloses a method for preparing high-purity silica from copper metallurgical tailings, comprising: S1: drying; S2: crushing and sieving; S3: acid leaching; S4: impurity removal treatment; S5: silica precipitation; and S6: post-treatment. This method achieves a technological breakthrough in preparing high-purity silica from copper metallurgical tailings through the complete impurity removal process in S4, resulting in improved silica content and whiteness of the product, and a significant reduction in iron, heavy metals, and total impurities, thereby further improving the purity and whiteness of the silica.

Description

Technical Field

[0001] This invention relates to the field of silica preparation technology, and in particular to a method for preparing high-purity silica using copper metallurgical tailings. Background Technology

[0002] Copper smelting tailings are solid waste generated during copper smelting. Their output is enormous. Direct storage not only occupies a large amount of land resources, but may also cause soil and water pollution due to the leakage of heavy metal ions. Therefore, the resource utilization of copper smelting tailings has important environmental significance and economic value.

[0003] Copper metallurgical tailings contain a certain amount of silicon (in the form of silicates). Based on this composition, existing technologies have developed processes for preparing silica (an electronic-grade silicon micropowder functional filler) from copper metallurgical tailings. The core process typically includes drying, crushing, acid leaching, silica precipitation, and post-treatment steps. This type of process converts the silicon in the tailings into soluble silicates through acid leaching, which then enters the filtrate. Silica is then generated through the silica precipitation step, achieving resource recovery of the tailings and reducing waste discharge pressure to some extent.

[0004] However, existing processes for preparing silica from copper metallurgical tailings have the following problems in practical applications:

[0005] Copper metallurgical tailings contain a significant amount of iron, which enters the filtrate as ferric ions during acid leaching. In the subsequent silica precipitation process, the residual ferric ions easily combine with hydroxide ions to form ferric hydroxide precipitate. This precipitate adheres firmly to the surface of silica particles, not only causing the finished silica to appear yellowish-gray and fail to meet whiteness standards, but also resulting in a high iron content in the product. In addition to iron ions, the acid leaching filtrate also contains trace amounts of heavy metal ions such as copper and zinc. These heavy metal ions will co-precipitate with silica particles during silica precipitation or form stable impurities in subsequent processing, leading to excessive heavy metal content in the product and seriously affecting the purity and whiteness of the silica.

[0006] Therefore, this application provides a method for preparing high-purity silica using copper metallurgical tailings to meet the demand. Summary of the Invention

[0007] The purpose of this application is to provide a method for preparing high-purity silica using copper metallurgical tailings, in order to solve the technical problem that the presence of ferric ions and trace heavy metal ions in the existing acid leaching process leads to a decrease in the purity and whiteness of the silica.

[0008] To achieve the above objectives, this application provides the following technical solution: a method for preparing high-purity silica using copper metallurgical tailings, comprising the following steps;

[0009] S1: Drying: Place the copper metallurgical tailings in a drying oven and dry them at 105-120℃ for 2-4 hours to obtain dried tailings.

[0010] At 105-120℃, free water in the tailings can be effectively removed, while avoiding changes in certain components in the tailings due to excessively high temperatures. The setting of the drying time is to ensure that the free water is completely removed. If the time is too short, the free water will not be completely removed, which will affect the subsequent crushing and other processes.

[0011] S2: Crushing and sieving: The dried tailings are crushed using a planetary ball mill with a ball-to-material ratio of 5-8:1, a rotation speed of 300-400 r / min, a crushing time of 1-2 hours, and then passed through a 400-600 mesh sieve to obtain tailings powder with a particle size ≤38μm.

[0012] The selection of the ball-to-material ratio, rotation speed, and crushing time was determined through multiple experiments. This combination of parameters ensures that the tailings are fully crushed, increasing the specific surface area, which is beneficial for the leaching of silicon in the subsequent acid leaching process. Passing the tailings through a 400-600 mesh sieve is to ensure that the tailings powder has a uniform particle size, meeting the requirements of subsequent reactions.

[0013] S3: Acid leaching. The tailings powder is mixed with sulfuric acid with a concentration of 1.5 mol / L at a liquid-to-solid ratio of (5-8):1 (mL / g). The mixture is placed in a reaction vessel and stirred at 50-80℃ for 2-4 hours at a stirring rate of 200-300 r / min. After the reaction is completed, a plate and frame filter is used to separate the solid and liquid to obtain acid leaching filtrate and acid leaching residue.

[0014] The liquid-to-solid ratio is chosen to ensure sufficient contact and reaction between the tailings powder and dilute acid. If the liquid-to-solid ratio is too low, the amount of dilute acid will be insufficient, resulting in incomplete reaction; if it is too high, it will increase subsequent processing costs. The reaction temperature and time are set because under these conditions, the silicates in the tailings can react fully with the dilute acid, improving the silicon dissolution rate. The stirring rate is controlled to ensure a uniform reaction system and promote the reaction.

[0015] S4: Impurity removal process, including the following steps;

[0016] S41: Add reduced iron powder to the acid leaching filtrate, and add reduced iron powder with a mass fraction of 92%-98%, the reduced iron powder being 1.2-1.5 times the content of ferric iron in the liquid. Stir and react at 40-60℃ for 0.5-1 hours. After the reaction is completed, use a plate and frame filter press to separate the solid and liquid to obtain a filtrate free of ferric iron.

[0017] The amount of reduced iron powder added is 1.2-1.5 times the content of ferric iron to ensure that Fe is reduced. 3+ Completely reduced to Fe 2 +This also causes the unreacted iron powder to become an "easily separable simple precipitate"; the reaction temperature and time are set because the reduction reaction can proceed efficiently under these conditions. If the temperature is too low or the time is too short, the reduction reaction will be incomplete and the Fe2+ will not be completely removed. 3+ All reduced to Fe 2+ .

[0018] S42: Take the filtrate after filtering S41, slowly add sulfuric acid with a concentration of 1.5 mol / L to it, adjust the pH of the filtrate to 2.5-3.0, stir at a speed of 200 r / min for 5 minutes;

[0019] The optimal pH range for citric acid to complex metal ions is 2.5-3.0. This range can increase the complexation constant of citric acid with ferrous iron and heavy metal ions (such as copper and zinc) by 2-3 times. Furthermore, sulfuric acid is a reagent already used in the original process, and no new impurities are introduced. This avoids incomplete complexation due to excessively high pH or damage to the structure of citric acid due to excessively low pH, thus laying the foundation for subsequent complexation and impurity removal.

[0020] Citric acid is a common and safe complexing agent. Its carboxyl group can form stable and soluble complexes with metal ions, preventing these ions from forming precipitates that adhere to the surface of silica during S5 silica precipitation. Furthermore, citric acid will be completely decomposed into carbon dioxide and water during the subsequent S64 spray drying (550-650℃), leaving no residue.

[0021] S43: Add 0.3-0.5% of food-grade citric acid (purity ≥99.5%) by weight of the filtrate, and continue stirring for 15 minutes to allow the citric acid to form stable complexes with metal ions such as ferrous iron, copper, and zinc in the filtrate.

[0022] S44: Dry the acid leaching residue in S3, pulverize it to 600 mesh, and add it to the filtrate of S43. The amount is 0.5-0.8% of the filtrate mass. After stirring for 20 minutes, filter it using a plate and frame filter press to obtain purified filtrate.

[0023] The acid leaching residue in S3 is rich in silanol groups (-Si-OH). After being crushed to 600 mesh, its specific surface area increases, which can physically adsorb trace impurities and citric acid complexes that have not been complexed. Moreover, the acid leaching residue is a by-product of the original process, so there is no need to prepare additional adsorbents, thus realizing waste utilization.

[0024] The S42, S43, and S44 steps in the entire S4 impurity removal process can further purify the filtrate after reduction, remove trace heavy metals and colloidal impurities not covered in S41, and provide a high-purity, low-turbidity reaction matrix for silica precipitation. This reduces impurity encapsulation in the silica during the precipitation stage, ultimately improving the purity and whiteness of the silica. The entire impurity removal process introduces new impurities into the subsequent finished silica.

[0025] S5: Precipitate silica. Transfer the purified filtrate to the reaction vessel, heat it to 60-80℃, stir at a speed of 250-350r / min, and slowly add surfactant and dispersant to separate the formed silica suspension into solid and liquid components.

[0026] S6: Post-processing, including the following steps;

[0027] S61: Centrifuge the silica suspension at 3000-4000 r / min for 10-15 minutes to obtain a filter cake;

[0028] The centrifugation speed and time are set to effectively separate the filter cake. If the speed is too low or the time is too short, the separation will be incomplete.

[0029] S62: Wash the filter cake with deionized water until the pH of the filtrate is 3-4 to remove residual iron salts and heavy ion residues, so that the impurity content of the finished silica product is less than 60ppm.

[0030] S63: Mix the filter cake with deionized water to form a slurry with a solid content of 20%, and adjust the pH to 6-8 using ammonia water so that the pH of the silica meets the industry requirements.

[0031] S64: Place the washed filter cake in a spray dryer with an inlet temperature of 550-650℃ and an outlet temperature of 100-120℃ to remove organic matter and hydroxyl groups, and obtain a high-purity silica product with a silica content of over 99.5%.

[0032] S65: High-purity silica is finely ground using an ultrafine grinding mill to form ultrafine silica powder.

[0033] In a preferred embodiment of this example, in step S41, reduced iron powder and deionized water are mixed at a mass ratio of 1:10 to form a suspension, which is then slowly added dropwise to the acid leaching filtrate at a rate of 10-15 mL / min using a metering pump. During the dropwise addition, the system stirring rate is maintained at 200-250 r / min to ensure that the suspension and filtrate are fully mixed.

[0034] In a preferred embodiment of this example, in step S46, food-grade citric acid is first mixed with a small amount of deionized water at a mass ratio of 1:5, and stirred at 40°C for 10 minutes to prepare a saturated solution. This solution is then added dropwise to the filtrate at a rate of 8-10 mL / min using a metering pump. During the addition process, the stirring rate is maintained at 200 r / min. After the addition is completed, stirring is continued for 15 minutes to ensure that the complexation reaction is complete.

[0035] As a preferred embodiment of this invention, the constant temperature vessel includes a vessel body, a stirring system, and an anti-stacking unit;

[0036] The upper and lower ends of the reactor body are respectively provided with a material inlet and a material outlet pipe;

[0037] The stirring system includes a stirring shaft with a stirring rod, and the stirring shaft is driven by a drive motor mounted on the upper end of the vessel body.

[0038] The anti-stacking unit is used to prevent the accumulation of reduced iron powder in the discharge pipe at the bottom.

[0039] As a preferred embodiment of this invention, the anti-stacking unit includes a blocking block adapted to the opening of the discharge pipe, a movable column, a rotating shaft, and a drive cylinder.

[0040] The stirring shaft is hollow, and the lower end of the stirring shaft is rotatably connected to the upper end of the blockage block;

[0041] The rotating shaft is rotatably mounted on the vessel body, with its lower end located in the inner cavity of the vessel body. The lower end of the rotating shaft is slidably mounted in the inner cavity of the stirring shaft. A limiting strip is provided on the outer wall of the rotating shaft, and a limiting groove adapted to the limiting strip is provided in the hollow cavity of the stirring shaft. A driven gear is mounted on the upper end of the rotating shaft, and the driven gear meshes with a drive gear mounted on the output shaft of the drive motor.

[0042] The rotating shaft is hollow, and the lower end of the movable column passes through the hollow cavity of the rotating shaft and is rotatably connected to the upper end of the blocking block.

[0043] The drive cylinder is installed at the upper end of the vessel body, and the movable end of the drive cylinder is connected to the movable column.

[0044] The blocking block is provided from bottom to top with an insertion part adapted to the opening of the discharge pipe, a frustum-shaped sealing part adapted to the opening, and a guide ring with an annular bevel.

[0045] As a preferred embodiment of this invention, a centrifugal throwing unit is also provided, which removes the impurities attached to the blockage block by causing the blockage block to rotate rapidly and using centrifugal force.

[0046] As a preferred embodiment of this invention, the centrifugal feeding unit includes a positioning rod, a first pinion, a second pinion, and a third large gear mounted on a mounting plate.

[0047] The movable column is provided with a hollow cavity in the vertical direction;

[0048] The mounting plate is installed on the upper end of the vessel body, the upper end of the positioning rod is rotatably connected to the mounting plate, the lower end of the positioning rod is located in the hollow cavity of the movable column, and a first magnet is provided in the bottom groove of the lower end of the positioning rod.

[0049] A second magnet is provided in the groove at the upper end of the blocking block;

[0050] The first and second pinions have the same specifications and are smaller than the third large gear. The first pinion is mounted on the positioning rod, and the first pinion, the second pinion, and the third large gear are meshed together.

[0051] The third large gear is driven by the drive motor.

[0052] As a preferred embodiment of this invention, an energy-saving unit is also provided, so that when the blocking block blocks the pipe opening, the drive motor cannot drive the third large gear to rotate.

[0053] When the blockage block moves upward to release the blockage at the pipe opening, the drive motor can drive the third large gear to rotate.

[0054] As a preferred embodiment of this example, the energy-saving unit includes a plate fixedly mounted on the movable column, a hollow tube rotatably mounted on the plate, a plug-in gear disk coaxially mounted with the third large gear, and a plug-in gear ring mounted on the outer wall of the hollow tube.

[0055] The hollow tube is sleeved on the output shaft of the drive motor, a limit rod is installed on the output shaft of the drive motor, and a vertical groove adapted to the limit rod is provided on the inner wall of the hollow tube.

[0056] In a preferred embodiment of this invention, a sliding column is slidably disposed in the inner cavity of the output end of the drive cylinder, and the upper end of the sliding column is fixedly connected to the movable column. A spring is disposed around the sliding column, and the upper and lower ends of the spring are fixedly connected to the movable column and the output end of the drive cylinder, respectively.

[0057] In summary, the technical effects and advantages of this invention are as follows:

[0058] 1. The present invention has a reasonable structure. The method achieves a technical breakthrough in the preparation of high-purity silica from copper metallurgical tailings through the S4 complete impurity removal process, which improves the silica content and whiteness of the product, and significantly reduces the content of iron, heavy metals and total impurities, thereby further improving the purity and whiteness of silica.

[0059] 2. In this invention, an anti-stacking unit is added to the constant temperature reactor body to avoid the accumulation of reduced iron powder at the discharge pipe, which would lead to incomplete reduction reaction and affect the quality of subsequent products.

[0060] 3. In this invention, a centrifugal throwing unit is also provided, which can automatically clean the impurities attached to the upper end of the blockage block, so as to avoid the formation of iron hydroxide precipitate during the silicon precipitation process due to the introduction of additional iron ions by iron powder particles, thereby reducing the black and white color of white carbon. Attached Figure Description

[0061] 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.

[0062] Figure 1 Tables showing experimental data for examples and comparative examples;

[0063] Figure 2 This is a schematic diagram of the cross-sectional structure of the thermostatic reactor.

[0064] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure of the stirring shaft and the rotating shaft;

[0065] Figure 4 for Figure 2 Schematic diagram of a partial structure of the constant temperature autoclave;

[0066] Figure 5 for Figure 4 Enlarged structural diagram at point A in the middle;

[0067] Figure 6 for Figure 4 Enlarged structural diagram at point B;

[0068] Figure 7 for Figure 2 Enlarged structural diagram at point C.

[0069] In the diagram: 1. Kettle body; 2. Stirring shaft; 3. Stirring rod; 4. Blocking block; 401. Guide ring; 402. Frustum-shaped sealing part; 403. Insertion part; 5. Rotating shaft; 501. Limiting strip; 6. Drive motor; 7. Drive gear; 8. Driven gear; 9. Drive cylinder; 10. Movable column; 11. First pinion; 12. Second pinion; 13. Third large gear; 14. Positioning rod; 15. Plate; 16. Insertion gear ring; 17. Hollow tube; 18. Limiting rod; 19. Sliding column; 20. Spring; 21. Insertion gear disc. Detailed Implementation

[0070] 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.

[0071] To verify the effectiveness of the method described in claim 1 in improving the purity and whiteness of silica, this experiment used the same batch of copper metallurgical tailings as raw material, set up 3 sets of example examples and 2 sets of comparative examples, and compared the core indicators of the products by controlling the variable method.

[0072] Experimental materials: Copper metallurgical tailings produced by a copper smelter were selected. The main components (mass fraction) were: SiO2 38.2%, Fe2O3 22.5%, CuO 0.35%, ZnO 0.28%, and the remainder were calcium and magnesium oxides and impurities.

[0073] Detection indicators and methods:

[0074] Silica content: determined using X-ray fluorescence spectrometry;

[0075] Whiteness: Measured using a Hunter LabScanXE whiteness meter, expressed as Hunter whiteness value (L*), with higher values ​​indicating better whiteness;

[0076] Iron content and heavy metal (Cu, Zn) content: detected by ICP-MS inductively coupled plasma mass spectrometry;

[0077] Total impurity content: determined by gravimetric method, unit is ppm.

[0078] Example 1

[0079] S1 Drying: Copper metallurgical tailings are placed in a drying oven and dried at 115℃ for 3 hours to obtain dried tailings.

[0080] S2 Crushing and Sieving: Planetary ball mill with a ball-to-material ratio of 6:1, rotation speed of 350 r / min, crushing for 1.5 h, passing through a 500 mesh sieve, yielding tailings powder with a particle size ≤38μm.

[0081] S3 acid leaching: Tailings powder is mixed with 1.5 mol / L sulfuric acid at a liquid-to-solid ratio of 6:1 (mL / g), placed in a reaction vessel, and reacted at 65℃ and a stirring rate of 250 r / min for 3 h. The acid leaching filtrate and acid leaching residue are obtained by plate and frame filtration.

[0082] S4 impurity removal process (core step)

[0083] S41: The acid leaching filtrate is transferred to a constant temperature reactor, and reduced iron powder (purity 95%, particle size ≤100μm) with a trivalent iron content 1.3 times that of the liquid is added. The mixture is stirred at 50℃ for 0.8h and filtered through a plate and frame filter to obtain a filtrate free of trivalent iron.

[0084] S42: Slowly add 1.5 mol / L sulfuric acid, adjust the pH of the filtrate to 2.8, stir at 200 r / min for 5 min.

[0085] S43: Add 0.4% (by weight of filtrate) of food-grade citric acid (99.6% purity), stir for 15 minutes to allow the citric acid to form stable complexes with ferrous, copper, and zinc ions.

[0086] S44: Dry and pulverize the S3 acid leaching residue to 600 mesh, add it at 0.6% of the filtrate mass, stir for 20 minutes, and filter through a plate and frame filter to obtain purified filtrate.

[0087] S5 Precipitation of Silica: The purified filtrate is transferred to a reaction vessel. At 70°C and a stirring rate of 300 r / min, a surfactant (sodium dodecylbenzenesulfonate, 0.1% added) and a dispersant (ammonium bicarbonate, 2 mol / L) are slowly added. The reaction is carried out for 2 hours to obtain a silica suspension.

[0088] S6 Post-processing

[0089] S61: Centrifuge the suspension for 12 minutes at a speed of 3500 r / min to obtain a filter cake.

[0090] S62: Wash the filter cake with deionized water until the filtrate pH=3.5 to remove residual salts.

[0091] S63: The filter cake is mixed with deionized water to form a slurry with a solid content of 20%, and the pH is adjusted to 7.0 with ammonia water.

[0092] S64: Spray drying, inlet temperature 600℃, outlet temperature 110℃, removes organic matter and hydroxyl groups.

[0093] S65: Grinding with an ultrafine grinder to obtain high-purity white carbon black powder.

[0094] Example 2

[0095] The differences from Example 1 are as follows:

[0096] S1: Dry at 105℃ for 2 hours;

[0097] S2: Particle-to-material ratio 5:1, rotation speed 300r / min, pulverize for 1 hour, pass through 400 mesh sieve;

[0098] S3: Liquid-to-solid ratio 5:1, reaction at 50℃ for 2 hours, stirring rate 200r / min;

[0099] S4: S41 Reduced iron powder addition is 1.2 times the ferric iron content, reaction at 40℃ for 0.5h; S42 Adjust pH to 2.5; S43 Citric acid addition is 0.3%; S44 Acid leaching residue addition is 0.5%;

[0100] S5: 60℃, stirring rate 250r / min; S6: centrifugation speed 3000r / min, time 10min; spray drying inlet 550℃, outlet 100℃; the remaining steps are the same as in Example 1.

[0101] Example 3

[0102] The differences from Example 1 are as follows:

[0103] S1: Dry at 120℃ for 4 hours; S2: Pellet-to-particle ratio 8:1, rotation speed 400r / min, pulverize for 2 hours, and pass through a 600-mesh sieve.

[0104] S3: Liquid-to-solid ratio 8:1, reaction at 80℃ for 4 hours, stirring rate 300r / min.

[0105] S4: S41 Reduced iron powder added at 1.5 times the content of ferric iron, reacted at 60℃ for 1 hour; S42 Adjusted pH to 3.0; S43 Citric acid added at 0.5%; S44 Acid leaching residue added at 0.8%.

[0106] S5: 80℃, stirring rate 350r / min; S6: centrifugation speed 4000r / min, time 15min; spray drying inlet 650℃, outlet 120℃; the remaining steps are the same as in Example 1.

[0107] Comparative Example 1 (Completely traditional process, without any impurity removal steps)

[0108] S1–S3: The steps are exactly the same as those in Example 1, yielding acid leaching filtrate and acid leaching residue.

[0109] S5 Precipitation of Silica (without S4 purification): The acid leaching filtrate is directly transferred into the reaction vessel, and the precipitation conditions are the same as in Example 1;

[0110] S6 post-processing: The process is exactly the same as step S6 in Example 1, yielding silica powder.

[0111] Comparative Example 2 (Traditional process + single reduction for impurity removal, without S42–S44)

[0112] S1–S3: Consistent with Example 1;

[0113] Simplified impurity removal: Only the S41 step of reducing iron powder to remove ferric iron is performed, and after filtration, the S5 step of silica precipitation is performed directly (without S42 pH adjustment, S43 complexation, or S44 adsorption).

[0114] S5–S6: Consistent with Example 1.

[0115] The experimental data of the above embodiments and comparative examples are as follows: Figure 1 As shown, by Figure 1 The experimental data shows that;

[0116] The silica content of Examples 1-3 is ≥99.5%, which is higher than that of Comparative Example 1 (97.2%) and Comparative Example 2 (98.5%). This is because the impurity removal process in S4 of claim 1 forms a purification system of "reduction + pH adjustment + complexation + adsorption".

[0117] S41 reduces ferric iron to easily separable ferrous iron precipitate, S42 adjusts the pH to the optimal range for citric acid complexation, S43 avoids co-precipitation by complexing heavy metal ions with citric acid, and S44 uses the silanol groups of acid leaching residue to adsorb residual impurities. The four stages work together to achieve deep purification.

[0118] In Comparative Example 1, there was no impurity removal step. Iron, copper, and zinc ions in the acid leaching filtrate directly entered the silica precipitation stage and co-precipitated with silica, significantly diluting the silica content.

[0119] The Hunter whiteness value of the example is ≥95.1, exceeding the industry standard and 13.6-15.0 units higher than that of Comparative Example 1;

[0120] The key factor affecting whiteness is iron content. In the example, the iron content is ≤18ppm, while in the comparative example, the iron content reaches 325ppm. The ferric hydroxide precipitate formed by ferric iron will make the silica appear yellowish-gray. The S4 process completely solves the problem of residual iron impurities.

[0121] The total Cu+Zn content of the example is ≤8ppm, which meets the requirements for electronic-grade silica applications; the heavy metal content of Comparative Example 1 is 7–11 times that of the example, making it unsuitable for high-end applications.

[0122] Conclusion: The method described in claim 1 achieves a technological breakthrough in the preparation of high-purity silica from copper metallurgical tailings through the complete S4 impurity removal process. Compared with the traditional process without the S4 step, the silica content of the product is increased by 2.3-2.6 percentage points, the whiteness is increased by more than 13 percentage points, the iron and heavy metal content is reduced by more than 90%, and the total impurity content is controlled within 60 ppm, fully meeting the stringent standards for electronic-grade silica.

[0123] like Figure 2 As shown, the thermostatic reactor includes a reactor body, a stirring system, and an anti-stacking unit;

[0124] The upper and lower ends of the vessel body 1 are respectively provided with a material inlet and a material outlet pipe;

[0125] The stirring system includes a stirring shaft 2 with a stirring rod 3, and the stirring shaft 2 is driven by a drive motor 6 mounted on the upper end of the vessel body 1.

[0126] The anti-stacking unit is used to prevent the accumulation of reduced iron powder in the discharge pipe located at the bottom.

[0127] In actual operation, there is a certain depth between the feed inlet of the discharge pipe and the electric valve installed at the lower end. In this space, reduced iron powder (granular) is prone to accumulate, resulting in incomplete reduction reaction and affecting the quality of subsequent products. Therefore, an anti-stacking unit is set up to solve this problem.

[0128] As a preferred embodiment of this example, Figure 2-4 and Figure 7 As shown, the anti-stacking unit includes a blocking block 4 adapted to the opening of the discharge pipe, a movable column 10, a rotating shaft 5, and a drive cylinder 9.

[0129] The stirring shaft 2 is hollow, and the lower end of the stirring shaft 2 is rotatably connected to the upper end of the blockage block 4;

[0130] The rotating shaft 5 is rotatably mounted on the vessel body 1. The lower end of the rotating shaft 5 is located in the inner cavity of the vessel body 1. The lower end of the rotating shaft 5 is slidably mounted in the inner cavity of the stirring shaft 2. A limiting strip 501 is provided on the outer wall of the rotating shaft 5, and a limiting groove adapted to the limiting strip 501 is provided in the hollow cavity of the stirring shaft 2. A driven gear 8 is installed on the upper end of the rotating shaft 5, and the driven gear 8 is meshed with the driving gear 7 installed on the output shaft of the drive motor 6.

[0131] The rotating shaft 5 is hollow, and the lower end of the movable column 10 passes through the hollow cavity of the rotating shaft 5 and is rotatably connected to the upper end of the blocking block 4.

[0132] The drive cylinder 9 is installed at the upper end of the vessel body 1, and the movable end of the drive cylinder 9 is connected to the movable column 10.

[0133] The blockage block 4 is provided with, from bottom to top, a plug-in part 403 that is adapted to the opening of the discharge pipe, a frustum-shaped sealing part 402 that is adapted to the opening, and a guide ring 401 with an annular inclined surface.

[0134] When using it, the initial state is as follows: Figure 1 As shown, the blocking block 4 (with an elastic sealing sleeve on its outer surface) seals the pipe opening, ensuring that iron powder does not accumulate in the discharge pipe cavity when the constant temperature reactor is working.

[0135] During operation, the drive motor 6 drives the rotating shaft 5 to rotate, and the rotating shaft 5 drives the stirring rod 3 on the stirring shaft 2 to rotate and stir the internal fluid. At the same time, since the stirring shaft 2 is rotatably connected to the blockage block 4, the blockage block 4 remains stationary during this process.

[0136] When it is necessary to discharge the fluid in the constant temperature reactor, the moving column 10 is driven upward by the drive cylinder 9. The moving column 10 will drive the stirring shaft 2 and the blockage block 4 to move upward as a whole, thereby releasing the seal blockage of the discharge pipe by the blockage block 4, so that there is a certain distance between the blockage block 4 and the bottom of the inner cavity of the reactor body 1, so as to avoid affecting the discharge speed of the fluid.

[0137] After the material discharge is completed, the control drive cylinder 9 drives the movable column 10 to move downward, thereby causing the blocking block 4 to block and seal the discharge pipe again.

[0138] It should be noted that: First, since this anti-accumulation unit is installed, there is no need to install an electric valve on its discharge pipe; Second, the setting of the frustum-shaped sealing part 402 makes the blockage block 4 form a block and fit tightly with the end of the pipe opening; and through the annular inclined surface on the guide ring 401, it is not easy for impurities to stay and accumulate on the upper end of the blockage block 4.

[0139] As a preferred embodiment of this invention, a centrifugal throwing unit is also provided, which removes the impurities attached to the blockage block 4 by rapidly rotating the blockage block 4 using centrifugal force.

[0140] During operation, impurities inevitably adhere to the upper end of the blockage block 6. To prevent these impurities from affecting the quality of subsequent fluids, cleaning is required. Therefore, a centrifugal slinging unit is set up to automatically clean the impurities on it (including unreacted reduced iron powder particles, a small amount of silicon-based colloids or other suspended impurities remaining after adsorption by acid leaching residue. These impurities will seriously affect the quality of subsequent fluids. Iron powder particles will introduce additional iron ions, leading to the formation of iron hydroxide precipitate during silicon precipitation, which reduces the blackness and whiteness of white carbon).

[0141] As a preferred embodiment of this example, Figure 4 and Figure 6 As shown, the centrifugal feeding unit includes a positioning rod 14, a first pinion 11, a second pinion 12, and a third large gear 13 mounted on the mounting plate;

[0142] The movable column 10 has a hollow cavity in the vertical direction;

[0143] The mounting plate is installed on the upper end of the vessel body 1. The upper end of the positioning rod 14 is rotatably connected to the mounting plate. The lower end of the positioning rod 14 is located in the hollow cavity of the movable column 10. A first magnet is provided in the bottom groove of the lower end of the positioning rod 14.

[0144] A second magnet is installed in the groove at the upper end of the shaft of the blocking block 4;

[0145] The first pinion 11 and the second pinion 12 have the same specifications and are smaller than the size of the third large gear 13. The first pinion 11 is mounted on the positioning rod 14, and the first pinion 11, the second pinion 12 and the third large gear 13 are meshed with each other.

[0146] The third gear 13 is driven by the drive motor 6.

[0147] When the drive motor 6 is working, it drives the stirring shaft 2 to rotate. When it is necessary to discharge material, the drive cylinder 9 causes the movable column 10 to move the block block 4 upward (without affecting the rotation of the stirring shaft 2). After moving to a certain height, the upward-moving block block 4 is fixed to the positioning rod 14 by the magnetic attraction between the first magnet and the second magnet (without affecting the subsequent separation).

[0148] The drive motor 6 drives the third large gear 13 to rotate, and the third large gear 13 drives the positioning rod 14 to rotate rapidly through two sets of small gears, which in turn drives the blockage block 4 to rotate rapidly. Through centrifugal force, the impurities on the blockage block 4 are thrown off, forming an automatic cleaning process.

[0149] As a preferred embodiment of this invention, an energy-saving unit is also provided so that when the blocking block 4 blocks the pipe opening, the drive motor 6 cannot drive the third large gear 13 to rotate.

[0150] When the blockage block 4 moves upward to release the blockage at the pipe opening, the drive motor 6 can drive the third large gear 13 to rotate.

[0151] By setting up an energy-saving unit, the drive motor 6 will drive the third gear 3 to rotate only when the blockage block 4 needs to be rotated to remove impurities. At other times, the drive motor 6 cannot drive the third gear 3 to rotate, thereby saving some power consumption.

[0152] As a preferred embodiment of this example, Figure 6 As shown, the energy-saving unit includes a plate 15 fixedly mounted on the movable column 10, a hollow tube 17 rotatably mounted on the plate 15, a plug-in gear 21 coaxially mounted with the third large gear 13, and a plug-in gear ring 16 mounted on the outer wall of the hollow tube 17.

[0153] Hollow tube 17 is sleeved on the output shaft of drive motor 6. Limiting rod 18 is installed on the output shaft of drive motor 6, and vertical grooves adapted to limiting rod 18 are provided on the inner wall of hollow tube 17.

[0154] When the drive cylinder 9 drives the movable column 10 to move upward, its rotating hollow tube 17 will move upward relative to the output axis of the drive motor 6, and complete the insertion of the toothed ring 16 and the toothed disc 21. At this time, the movable column 10 stops moving. Through the insertion of the toothed ring 16 and the toothed disc 21, the third large gear 13 is driven to rotate. Through the cooperation of the two sets of small gears, the positioning rod 14 drives the block block 4 to rotate rapidly. The impurities on it are removed by the action of centrifugal force. After the material is thrown (the material is thrown during the discharge operation, the stirring shaft 2 can stir the fluid, and the flowing fluid can scour the surface of the block block 4, which is more conducive to the removal of impurities on it) and after the discharge is completed, the drive cylinder 9 is controlled to move the movable column 10 and the hollow tube 17 downward, and finally complete the sealing and blocking of the discharge pipe by the block block 4 and the insertion and separation of the toothed ring 16 and the toothed disc 21.

[0155] It should be noted that: First, during centrifugal discharge, the rotation direction of the blockage block 4 is opposite to that of the stirring shaft 2. This causes the rotation direction of the fluid inside the vessel 1 to be opposite to that of the blockage block 4, which greatly increases the relative velocity between the fluid and the surface of the blockage block 4, and enhances the scouring force of the fluid on the surface of the blockage block. This reverse scouring can quickly remove the impurities that have been thrown off by centrifugal force, preventing the impurities from re-attaching to the surface of the blockage block 4, and further improving the cleaning effect. Second, the upper ends of the insertion toothed ring 16 and the insertion toothed disc 21 are both circumferentially equipped with positioning teeth of isosceles triangular structure, and there is an insertion gap between adjacent sets of positioning teeth.

[0156] As a preferred embodiment of this example, Figure 5 As shown, a sliding column 19 is slidably arranged in the inner cavity of the output end of the drive cylinder 9, and the upper end of the sliding column 19 is fixedly connected to the movable column 10. A spring 20 is arranged around the sliding column 19, and the upper and lower ends of the spring 20 are fixedly connected to the movable column 10 and the output end of the drive cylinder 9, respectively.

[0157] The spring 20 can buffer the contact pressure between the blockage block 4 and the discharge pipe.

[0158] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is 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 preparing high-purity silica using copper metallurgical tailings, characterized in that: Includes the following steps; S1: Drying: Place the copper metallurgical tailings in a drying oven and dry them at 105-120℃ for 2-4 hours to obtain dried tailings. S2: Crushing and sieving: The dried tailings are crushed using a planetary ball mill with a ball-to-material ratio of 5-8:1, a rotation speed of 300-400 r / min, a crushing time of 1-2 hours, and then passed through a 400-600 mesh sieve to obtain tailings powder with a particle size ≤38μm. S3: Acid leaching. The tailings powder is mixed with sulfuric acid with a concentration of 1.5 mol / L at a liquid-to-solid ratio of (5-8):1 (mL / g). The mixture is placed in a reaction vessel and stirred at 50-80℃ for 2-4 hours at a stirring rate of 200-300 r / min. After the reaction is completed, a plate and frame filter is used to separate the solid and liquid to obtain acid leaching filtrate and acid leaching residue. S4: Impurity removal process, including the following steps; S41: Pour the acid leaching filtrate into a constant temperature vessel and add reduced iron powder with a mass fraction of 92%-98%, the reduced iron powder being 1.2-1.5 times the content of ferric iron in the liquid. Stir and react at 40-60℃ for 0.5-1 hours. After the reaction is completed, use a plate and frame filter press to separate the solid and liquid to obtain a filtrate free of ferric iron. S42: Take the filtrate after filtering S41, slowly add sulfuric acid with a concentration of 1.5 mol / L to it, adjust the pH of the filtrate to 2.5-3.0, stir at a speed of 200 r / min for 5 minutes; S43: Add 0.3-0.5% of food-grade citric acid (purity ≥99.5%) by weight of the filtrate, and continue stirring for 15 minutes to allow the citric acid to form stable complexes with metal ions such as ferrous iron, copper, and zinc in the filtrate. S44: Dry the acid leaching residue in S3, pulverize it to 600 mesh, and add it to the filtrate of S43. The amount is 0.5-0.8% of the filtrate mass. After stirring for 20 minutes, filter it using a plate and frame filter press to obtain purified filtrate. S5: Precipitate silica. Transfer the purified filtrate to the reaction vessel, heat it to 60-80℃, stir at a speed of 250-350r / min, and slowly add surfactant and dispersant to separate the formed silica suspension into solid and liquid components. S6: Post-processing, including the following steps; S61: Centrifuge the silica suspension at 3000-4000 r / min for 10-15 minutes to obtain a filter cake; S62: Wash the filter cake with deionized water until the pH of the filtrate is 3-4 to remove residual iron salts and heavy ion residues, so that the impurity content of the finished silica product is less than 60ppm. S63: Mix the filter cake with deionized water to form a slurry with a solid content of 20%, and adjust the pH to 6-8 using ammonia water so that the pH of the silica meets the industry requirements. S64: Place the washed filter cake in a spray dryer with an inlet temperature of 550-650℃ and an outlet temperature of 100-120℃ to remove organic matter and hydroxyl groups, and obtain a high-purity silica product with a silica content of over 99.5%. S65: High-purity silica is finely ground using an ultrafine grinding mill to form ultrafine silica powder.

2. The method for preparing high-purity silica from copper metallurgical tailings according to claim 1, characterized in that: The thermostatic reactor includes a reactor body, a stirring system, and an anti-stacking unit; The upper and lower ends of the vessel body (1) are respectively provided with a material inlet and a material discharge pipe; The stirring system includes a stirring shaft (2) with a stirring rod (3), and the stirring shaft (2) is driven by a drive motor (6) mounted on the upper end of the vessel body (1); The anti-stacking unit is used to prevent the accumulation of reduced iron powder in the discharge pipe at the bottom.

3. The method for preparing high-purity silica from copper metallurgical tailings according to claim 2, characterized in that: The anti-stacking unit includes a blocking block (4) adapted to the opening of the discharge pipe, a movable column (10), a rotating shaft (5), and a drive cylinder (9). The stirring shaft (2) is hollow, and the lower end of the stirring shaft (2) is rotatably connected to the upper end of the block (4); The rotating shaft (5) is rotatably mounted on the vessel body (1). The lower end of the rotating shaft (5) is located in the inner cavity of the vessel body (1). The lower end of the rotating shaft (5) is slidably mounted in the inner cavity of the stirring shaft (2). A limiting strip (501) is provided on the outer wall of the rotating shaft (5). A limiting groove adapted to the limiting strip (501) is provided in the hollow cavity of the stirring shaft (2). A driven gear (8) is installed on the upper end of the rotating shaft (5). The driven gear (8) is meshed with the driving gear (7) installed on the output shaft of the drive motor (6). The rotating shaft (5) is hollow, and the lower end of the movable column (10) passes through the hollow cavity of the rotating shaft (5) and is rotatably connected to the upper end of the blocking block (4). The drive cylinder (9) is installed at the upper end of the vessel body (1), and the movable end of the drive cylinder (9) is connected to the movable column (10). The blocking block (4) is provided from bottom to top with a plug-in part (403) adapted to the opening of the discharge pipe, a frustum-shaped sealing part (402) adapted to the opening, and a guide ring (401) with an annular inclined surface.

4. The method for preparing high-purity silica from copper metallurgical tailings according to claim 3, characterized in that: It is also equipped with a centrifugal throwing unit, which removes the impurities attached to the block (4) by making the block (4) rotate rapidly and using centrifugal force.

5. The method for preparing high-purity silica from copper metallurgical tailings according to claim 4, characterized in that: The centrifugal feeding unit includes a positioning rod (14), a first pinion (11), a second pinion (12), and a third large gear (13) mounted on the mounting plate. The movable column (10) has a hollow cavity in the vertical direction; The mounting plate is installed on the upper end of the vessel body (1), the upper end of the positioning rod (14) is rotatably connected to the mounting plate, the lower end of the positioning rod (14) is located in the hollow cavity of the movable column (10), and a first magnet is provided in the bottom groove of the lower end of the positioning rod (14). A second magnet is provided in the groove at the upper end of the blocking block (4); The first pinion (11) and the second pinion (12) have the same specifications and are smaller than the size of the third large gear (13). The first pinion (11) is mounted on the positioning rod (14). The first pinion (11), the second pinion (12) and the third large gear (13) are meshed with each other. The third large gear (13) is driven by the drive motor (6).

6. The method for preparing high-purity silica from copper metallurgical tailings according to claim 5, characterized in that: An energy-saving unit is also provided so that when the blockage block (4) blocks the pipe opening, the drive motor (6) cannot drive the third large gear (13) to rotate. When the blockage block (4) moves upward to release the blockage of the pipe opening, the drive motor (6) can drive the third large gear (13) to rotate.

7. The method for preparing high-purity silica from copper metallurgical tailings according to claim 6, characterized in that: The energy-saving unit includes a plate (15) fixedly mounted on the movable column (10), a hollow tube (17) rotatably mounted on the plate (15), a plug-in gear disc (21) coaxially mounted with the third large gear (13), and a plug-in gear ring (16) mounted on the outer wall of the hollow tube (17). The hollow tube (17) is sleeved on the output shaft of the drive motor (6), and a limit rod (18) is installed on the output shaft of the drive motor (6). A vertical groove adapted to the limit rod (18) is provided on the inner wall of the hollow tube (17).

8. The method for preparing high-purity silica from copper metallurgical tailings according to claim 3, characterized in that: The output end cavity of the drive cylinder (9) is slidably provided with a sliding column (19), and the upper end of the sliding column (19) is fixedly connected to the movable column (10). A spring (20) is provided around the sliding column (19), and the upper and lower ends of the spring (20) are fixedly connected to the movable column (10) and the output end of the drive cylinder (9), respectively.

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