Method for increasing content of iron oxide in red mud

Abstract

The invention discloses a method for increasing the content of iron oxide in red mud. Compared with the prior art, the method has the following beneficial effects: the problems of high ore consumption caused by insufficient recovery of AL2O3 dissolved out from the laterite type high-iron low-silicon guineite at low temperature, influence on system efficiency, energy consumption and product quality due to harsh desilicication conditions, incapability of realizing full-quantitative utilization of red mud and low comprehensive utilization degree of resources are solved; comprising the following steps: preparing materials: obtaining red mud ore pulp, diluting and separating the red mud ore pulp, adding an auxiliary agent into diluted and separated underflow, and adding mother liquor for secondary adjustment to obtain red mud slurry; dissolving out at high temperature; heating the red mud slurry to a preset temperature T1, and maintaining for 1-2 hours at the preset temperature T1; filtering the slurry; and diluting and separating the slurry subjected to high-temperature dissolution treatment.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum oxide preparation, and in particular to a method for increasing the iron oxide content in red mud. Background Art

[0002] In recent years, my country's alumina production has been increasing year by year. With the increase in alumina production capacity and increasingly stringent environmental protection requirements, the problem of domestic bauxite resource shortage has become more prominent, resulting in a surge in the use of imported bauxite. Among the imported ores, Guinea has become one of my country's main sources of bauxite because of its high ore resources, good mining conditions, high ore grade, and an average alumina content of more than 45%.

[0003] Guinea's ore is mainly laterite bauxite, which is typically characterized by high iron (iron oxide content) and low silicon (silicon dioxide content is 1-3.5% on average). Therefore, my country's use of this type of ore to produce alumina mainly relies on the low-temperature (140-145°C) dissolution process.

[0004] Guinea bauxite is mainly laterite-type high-iron low-silicon bauxite. Because it contains a small amount of boehmite (3-5%), it cannot undergo dissolution reaction under low-temperature dissolution (145-155°C), resulting in a high content of alumina in the dissolved red mud, which increases the consumption of product ore. At the same time, since the Fe2O3 content in the low-temperature dissolved red mud is 53%-58%, it does not meet the requirement of downstream utilization content ≥60%. Only 10-20% can be selected through the existing red mud iron selection technology, and the tailings after selection have no economic value and can only be stored, and a large amount of red mud is forced to be stored.

[0005] By analyzing the operating conditions of the Guinea mine that was used in the past, due to its high iron and low silicon characteristics, if the Al2O3 in the red mud can be reduced to below 10%, the iron oxide content in the red mud can reach the target of ≥60%.

[0006] This requires the dissolution of boehmite in the ore. At present, the industry mainly adopts high-temperature dissolution to improve the dissolution of boehmite. However, high-temperature dissolution has disadvantages and problems such as high steam cost, high alkali consumption, and easy to cause the increase of oxalate (high-temperature decomposition of organic matter). Therefore, low-temperature dissolution of Guinea ore is still the main method in China, which not only wastes resources, but also affects the resource utilization of red mud. Large-scale storage causes land waste and increases environmental risks.

[0007] Therefore, for the high-iron and low-silicon Guinea bauxite, there is an urgent need for a technology that is easy to industrialize and can be easily integrated into the existing alumina production process to further recover alumina and increase the iron oxide content in red mud to meet downstream utilization requirements. Summary of the invention

[0008] The purpose of the present invention is to solve the above problems and provide a method for increasing the iron oxide content in red mud so that the red mud can meet the full quantitative utilization.

[0009] To achieve the above object, the technical solution of the present invention is: a method for increasing the iron oxide content in red mud, comprising the following steps: Batching: obtaining red mud slurry, diluting and separating the red mud slurry, adding additives to the underflow after dilution and separation, and adding mother liquor for secondary adjustment to obtain red mud slurry; High temperature dissolution: heating the red mud slurry to a predetermined temperature T1 and maintaining the temperature at T1 for 1-2 hours; Slurry filtration; dilution and separation of slurry after high temperature dissolution treatment.

[0010] Furthermore, the adding of an auxiliary agent to the underflow after dilution and separation comprises: The slurry is diluted and separated, and when the liquid-to-solid ratio of the underflow reaches 1: (1.8-2.2), additives are added to the underflow.

[0011] Furthermore, the additive is lime, and the addition ratio of lime is 1%-10%.

[0012] Furthermore, after the mother liquor is added for secondary adjustment, the caustic soda concentration of the red mud slurry is obtained to be 160 g / l-200 g / l.

[0013] Furthermore, the predetermined temperature T1 has a value range of 200°C-300°C.

[0014] Further, obtaining red mud slurry includes: First batching: control the caustic soda concentration in the slurry to 180 g / l -200 g / l; Pre-desiliconization: The slurry obtained from the first batch is heated to 90°C-100°C and maintained at this temperature for 12-16 hours for desiliconization treatment; Low temperature dissolution: add alkali solution to the ore pulp that has undergone pre-desiliconization dissolution treatment, keep it warm at 140℃-145℃ for 50 minutes-70 minutes to dissolve it, and obtain red mud slurry.

[0015] Furthermore, in the first batching, the concentration of sodium aluminate in the slurry is 200g / l-240g / l, and the solid content is 350g / l-450g / l. Furthermore, in low temperature dissolution, after adding alkali solution to the ore pulp, the caustic soda concentration in the ore pulp is 190 g / l-200 g / l, and the solid content is 200 g / l-300 g / l.

[0016] Further, in the batching step, diluting the red mud slurry includes: A predetermined amount of diluent is filled in the dilution chamber, and the low-temperature dissolved slurry is introduced into the dilution chamber through an introduction pipe arranged at the top of the dilution chamber. The slurry enters the dilution chamber from top to bottom through the leak plate, and is stirred by the stirring shaft to improve the dilution efficiency.

[0017] Furthermore, it also includes: The liquid pump works to suck and pump the material at the bottom of the dilution chamber to the inlet pipe.

[0018] The method for increasing the iron oxide content in red mud disclosed in the present invention has the following beneficial effects compared with the prior art: 1. This process technology solves the problems of insufficient recovery of AL2O3 from low-temperature dissolution of laterite-type high-iron and low-silicon Guinea bauxite, resulting in high ore consumption, harsh desiliconization conditions affecting system efficiency, energy consumption and product quality, inability to fully utilize red mud, and low comprehensive resource utilization.

[0019] 2. After the low-temperature leached red mud is subjected to secondary batching, high-temperature leaching is performed again to further recover the boehmite that was not dissolved in the low-temperature leaching process and the gibbsite that was not completely dissolved, thereby improving the recovery rate of bauxite. The Al2O3 content in the leached red mud drops to less than 10%. Under the condition of unchanged ore consumption, the unit capacity is increased by more than 15%.

[0020] 3. The batching conditions of this type of ore have been optimized, and the silicon content index of the semen has been increased through high-temperature dissolution, which solves the problem of difficulty in desiliconization of Guinea bauxite with high NK concentration under low-temperature dissolution conditions. The NK concentration of the ore can reach more than 195g / l, which solves the restrictive effects of the silicon content index and production capacity and improves the production capacity under low-temperature dissolution conditions.

[0021] 4. The reduction of red mud has been achieved. The increase of iron content in red mud has created conditions for the subsequent application of solid waste.

[0022] 5. The goethite in red mud is modified into hematite under high temperature conditions, the sedimentation performance of red mud is greatly improved, and the flocculant consumption is reduced by more than 10%.

[0023] 6. The modified red mud can meet the production needs of the downstream steel industry, achieve full quantitative utilization, and increase the resources for the iron ore source of steel enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a process flow diagram of a method for increasing the iron oxide content in red mud.

[0025] Figure 2 The present invention is a schematic diagram of the structure of a treatment system in a method for increasing the iron oxide content in red mud.

[0026] Figure 3 The present invention is a schematic diagram of the structure of a dilution unit in a method for increasing the iron oxide content in red mud.

[0027] Figure 4 The figure is a schematic diagram of the external structure of a dilution chamber in a method for increasing the iron oxide content in red mud according to the present invention.

[0028] Figure 5 The figure is a schematic diagram of the internal structure of a dilution chamber in a method for increasing the iron oxide content in red mud of the present invention.

[0029] Figure 6 Schematic diagram of the connection structure of the drain plate and the stirring shaft in the method for increasing the iron oxide content in red mud of the present invention Figure 1 .

[0030] Figure 7 Schematic diagram of the connection structure of the material mixing plate and the stirring shaft in the method for increasing the iron oxide content in red mud of the present invention Figure 2 .

[0031] Figure 8 The present invention is a schematic diagram of the structure of a suction assembly in a method for increasing the iron oxide content in red mud.

[0032] Fig. 9 The present invention is a schematic diagram of the structure of a suction pipe in a method for increasing the iron oxide content in red mud.

[0033] Fig.10 For the present invention Figure 5 Schematic diagram of the enlarged structure at point A in the middle.

[0034] Fig.11 For the present invention Figure 5 Schematic diagram of the enlarged structure at point B in the middle.

[0035] Fig.12 For the present invention Fig.11 Schematic diagram of the enlarged structure at point C in the middle.

[0036] In the figure: 1. Pre-desiliconization tank 1; 21. Low temperature dissolution unit 1; 22. Low temperature dissolution unit 2; 3. Dilution unit; 30. Dilution chamber; 301. Inlet pipe; 302. Discharge pipe; 31. Liquid pump; 310. Delivery pipe; 311. Rotary sleeve; 3110. Connecting pipe; 32. Stirring motor; 33. Top cover; 34. Stirring shaft; 341. Stirring rod; 343. Wire arrangement channel; 35. Leakage plate; 36, suction pipe; 36a, suction hole; 36b, comb teeth; 36c, connecting flange; 360, first rotating sleeve; 361, first connecting sleeve; 3610, gear ring; 3611, connecting shaft; 3612, flow channel; 362, intermediate gear shaft; 363, first gear shaft; 3631, first friction plate; 364, spline sleeve; 3641, guide rod; 3642, guide sleeve; 365, third connecting sleeve; 366, electromagnet; 367, second friction plate; 3671, second permanent magnet; 37, material leveling plate; 370, first permanent magnet; 371, second connecting sleeve; 372, coil; 373, second rotating sleeve; 374, third rotating sleeve; 4. First separation tank; 5. Second pre-desiliconization tank; 6. High-temperature dissolution unit; 7. Second separation tank; 8. Washing tank. DETAILED DESCRIPTION

[0037] The present invention will now be described in further detail with reference to the accompanying drawings. The accompanying drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and thus only show the components related to the present invention.

[0038] Please refer to Figure 1-2 The present application provides a method for increasing the iron oxide content in red mud, comprising the following steps: Batching: obtaining red mud slurry, diluting and separating the red mud slurry, adding additives to the underflow after dilution and separation, and adding mother liquor for secondary adjustment to obtain red mud slurry; High temperature dissolution: heating the red mud slurry to a predetermined temperature T1 and maintaining the temperature at T1 for 1-2 hours; Slurry filtration; dilution and separation of slurry after high temperature dissolution treatment.

[0039] Furthermore, the adding of an auxiliary agent to the underflow after dilution and separation comprises: The slurry is diluted and separated, and when the liquid-to-solid ratio of the underflow reaches 1: (1.8-2.2), additives are added to the underflow.

[0040] Specifically, the present application is based on obtaining red mud slurry after low-temperature dissolution of bauxite, specifically: low-temperature dissolution is performed after derailment dissolution through a pre-desiliconization tank 1, and low-temperature dissolution is performed simultaneously with a low-temperature dissolution unit 1 21 and a low-temperature dissolution unit 2 22 during low-temperature dissolution, and the dissolution slurry is obtained after low-temperature dissolution, that is, red mud slurry is obtained, and then the red mud slurry is diluted by a dilution unit 3 and separated by a first separation tank 4 to obtain an underflow, and an auxiliary agent is added to the underflow according to a ratio, and the mother liquor is added to adjust the concentration of the alkali solution to obtain a red mud slurry, and then the red mud slurry is subjected to high-temperature dissolution treatment by a high-temperature dissolution unit 6. High-temperature dissolution can improve the recovery rate of bauxite for the soluble monohydrate soft stone and the incompletely dissolved gibbsite in the red mud slurry, and improve the recovery rate of bauxite. The Al2O3 content in the dissolved red mud drops to below 10%. Under the condition that the ore consumption remains unchanged, the unit capacity is increased by more than 15%. Then, the high-temperature dissolved slurry is diluted and separated by another set of dilution units 3 and a second separation tank 7, and the overflow after separation is mixed with the overflow obtained in the batching step and filtered by a leaf filter system to obtain qualified semen. The dissolved slag obtained is washed by a washing tank 8 to obtain the treated red mud. In the above manner, the goethite in the red mud is modified into hematite under high temperature conditions, and the sedimentation performance of the red mud is greatly improved, which can reduce the amount of flocculant used, and the flocculant consumption is reduced by more than 10%; the iron oxide content in the obtained red mud can reach more than 60%, which can meet the production needs of the downstream steel industry, and can be used as a raw material for slag-making agents, pellets, etc. in the steel industry, to achieve full-scale utilization of sludge, increase resources for the iron ore source of steel enterprises, and make better use of the red mud produced by Guinea bauxite, reduce red mud accumulation, and improve environmental protection.

[0041] Furthermore, as a specific implementation, the additive is lime, and the addition ratio of lime is 1%-10%.

[0042] Further, as a specific implementation, after the mother liquor is added for secondary adjustment, the caustic soda concentration of the obtained red mud slurry is: 160g / l-200g / l.

[0043] Further, as a specific implementation, the predetermined temperature T1 has a value range of 200°C-300°C.

[0044] Further, as a specific implementation, the obtaining of red mud slurry includes: First batching: Control the caustic soda concentration in the slurry to 195 g / l -200 g / l; By optimizing the batching, the caustic soda concentration of the batched slurry is controlled above 195 g / l to improve the dissolution effect in the dissolution stage.

[0045] Pre-desiliconization: The slurry obtained from the first batch is heated to 90°C-100°C and maintained at this temperature for 12-16 hours for desiliconization treatment; Low temperature dissolution: add alkali solution to the ore pulp that has undergone pre-desiliconization dissolution treatment, keep it warm at 140℃-145℃ for 50 minutes-70 minutes to dissolve it, and obtain red mud slurry.

[0046] Furthermore, in the first batching, the concentration of sodium aluminate in the slurry is 200g / l-240g / l, and the solid content is 350g / l-450g / l. Further, as a specific implementation, in low temperature dissolution, after adding alkali solution to the ore pulp, the caustic soda concentration in the ore pulp is 190 g / l-200 g / l, and the solid content is 200 g / l-300 g / l.

[0047] Further, as a specific implementation, in the batching step, diluting the red mud slurry includes: A predetermined amount of diluent is filled in the dilution chamber 30, and the low-temperature dissolved slurry is introduced into the dilution chamber 30 through the introduction pipe 301 arranged at the top of the dilution chamber 30. The slurry enters the dilution chamber 30 from top to bottom through the leak plate 35, and the dilution efficiency is improved by stirring the stirring shaft. By setting the red mud slurry in the above manner, the dilution efficiency of the slurry and the diluent can be improved, and the production efficiency can be improved.

[0048] Furthermore, it also includes: The liquid pump 31 works to pump the material at the bottom of the dilution chamber 30 to the inlet pipe 301. During the dilution operation, if the slurry is not broken up and the diluent is not mixed evenly, the dense slurry sinks to the bottom of the dilution chamber 30. The slurry at the bottom of the dilution chamber 30 is pumped back to the inlet pipe 301 by the liquid pump 31 and mixed again with the slurry entering the pump, thereby further improving the mixing efficiency. As a preferred embodiment, refer to Figure 2 After high-temperature dissolution in the high-temperature dissolution unit, the slurry is diluted by another set of dilution units, which can also improve the dilution efficiency.

[0049] Further, as a specific implementation method, refer to Figure 3-Figure 12The specific structure of the dilution unit 3 is as follows: it includes a columnar dilution chamber 30, a top cover 33 arranged on the top of the dilution chamber, a leak plate 35 arranged on the upper end of the dilution chamber 30, and a stirring shaft 34 rotatably arranged on the top cover 33. A through hole for the stirring shaft to pass through is arranged at the center of the leak plate. A stirring rod 341 is arranged on the outer peripheral surface of the stirring shaft below the leak plate 35. Leakage holes are evenly distributed on the leak plate 35. An inlet pipe 301 is arranged on the top cover 33, which is located above the leak plate. The stirring shaft is connected to at least one material mixing plate 37. Along the rotation direction of the stirring shaft, the material mixing plate is arranged to be inclined upward from one end to the other end. The lower part of the material mixing plate 37 is arranged to be inclined upward from one end to the other end. The end portion contacts the upper surface of the leak plate 35. When working, a certain amount of diluent is filled in the dilution chamber 30, and the stirring motor 32 drives the stirring shaft to rotate and drives the leveling plate 37 to rotate. The red mud slurry is introduced from the inlet pipe 301, falls on the leak plate 35, and is spread by the leveling plate 37 to improve the uniformity, and then falls through the through hole on the leak plate 35 to the dilution chamber below, and then is stirred and mixed by the stirring rod for dilution, thereby improving the dilution efficiency. After a predetermined amount of red mud slurry is introduced in proportion, the introduction of the slurry is stopped. After the materials in the dilution chamber are evenly mixed, the dilution requirement is met, and then it can be discharged from the discharge pipe 302.

[0050] Further, as a preferred embodiment, the lower end of the stirring shaft 34 is driven to be connected to a suction pipe 36, and the suction pipe is arranged along the radial direction of the dilution chamber. Fig. 9 The outer circumferential surface of the suction pipe is provided with a suction hole 36a facing downward, a comb tooth 36b extending downward, and a connecting flange 36c is provided at the end thereof, which is connected to the stirring shaft through the connecting flange. A connecting shaft 3611 coaxially arranged with the stirring shaft is connected near the suction pipe 36, and the connecting shaft extends out of the bottom of the dilution chamber 30. A rotating sleeve 311 is rotatably provided at the lower end of the connecting shaft, and a flow channel 3612 connecting the inside of the suction pipe and the rotating sleeve is provided in the connecting shaft 3611. The rotating sleeve is connected to the liquid pump 31 through the connecting pipe 3110, and the output end of the liquid pump is connected to the introduction pipe 301 through the delivery pipe 310. When the stirring shaft 34 rotates, the suction pipe 36 can be driven to rotate. The comb teeth of the suction pipe 36 can comb and break the slurry deposited at the bottom of the dilution chamber. At this time, the liquid pump works to provide suction force to the suction pipe, so that the slurry broken by the comb teeth can be sucked into the introduction pipe 301 through the suction hole 36a, and then enters the dilution chamber from top to bottom again, and is diluted again to ensure the effect of mixing and dilution. In addition, by introducing the slurry at the bottom of the dilution chamber into the introduction pipe, it is mixed with the red mud slurry introduced by the introduction pipe to reduce the concentration of the slurry, disperse the slurry, improve the fluidity, increase the speed of passing through the leak plate, and improve the mixing efficiency.

[0051] Further, refer to Figure 6-Figure 11The outer rotating sleeve 373 of the stirring shaft 34 is provided with a second rotating sleeve 373 with axial limiting cooperation, and the stirring shaft 34 is also provided with a third rotating sleeve 374. The second rotating sleeve 373 is coaxially arranged and detachably fixedly connected with the second connecting sleeve 371. The second connecting sleeve 371 is connected to the third rotating sleeve 374. A coil 372 is arranged on the side wall of the second connecting sleeve 371 and on the outer area of ​​the stirring shaft 34 surrounded by the second connecting sleeve 371, and the other is provided with a first permanent magnet 370. The material leveling plate 37 is connected to the outer wall of the second connecting sleeve 371.

[0052] refer to Fig.10 , Fig.11 The lower end of the stirring shaft is rotatably connected and axially limited with a first rotating sleeve 360, the lower end of the first rotating sleeve 360 ​​is coaxially and detachably fixedly connected with a first connecting sleeve 361, the lower end of the first connecting sleeve is sealed, the connecting shaft 3611 is coaxially arranged at the lower end of the first connecting sleeve, the suction pipe is detachably fixedly connected to the first connecting sleeve through a connecting flange 36c, the lower end of the stirring shaft 34 extending into the first connecting sleeve is reduced in diameter and provided with a step shaft, the outer peripheral surface of the step shaft is provided with a spline groove along the axial direction, and the step shaft is sleeved with a spline groove The key sleeve 364, the lower end of the spline sleeve is detachably fixedly connected with the third connecting sleeve 365, the lower end of the third connecting sleeve is coaxially rotatably provided with a first gear shaft 363, the first gear shaft and the third connecting sleeve are axially limited, the upper end of the first gear shaft extending into the third connecting sleeve is coaxially provided with a first friction plate 3631, a gear ring 3610 is provided on the inner circumferential surface of the first connecting sleeve, an intermediate gear shaft 362 is rotatably provided on the lower end surface of the first connecting sleeve 361, and the intermediate gear shaft is transmission-connected with the gear ring 3610 and the first gear shaft 363, reference Fig.10 The lower end of the spline sleeve 364 is provided with at least two guide rods 3641 around the axis. The guide sleeve on the guide rod 3641 is provided with a guide sleeve 3642. The lower end of the guide sleeve is connected to a second friction plate 367. The second friction plate 367 is coaxially arranged with the first friction plate. The upper surface of the second friction plate 367 is provided with a second permanent magnet 3671. The lower end of the stirring shaft is provided with an electromagnet 366. The stirring shaft is provided with a wire arrangement channel 343. The wire arrangement channel is provided with a connecting wire harness connecting the second electromagnet 366 and the coil 372. Through the above-mentioned arrangement, magnetic resistance is generated between the first permanent magnet 370 on the second connecting sleeve 371 and the coil. Figure 7When the stirring shaft rotates in the rotation direction, the magnetic resistance can drive the second connecting sleeve 371 to rotate, thereby driving the material leveling plate 37 to rotate. When the slurry is stirred and diluted by the dilution component, the slurry enters from the inlet pipe and falls on the leak plate 35. The slurry is evenly spread by the material leveling plate 37, and then the material falls through the leak plate. Due to the high concentration of the slurry, the speed of falling through the leak plate is slow, so it will provide a reaction force to the material leveling plate, and control the stirring shaft to rotate at a certain speed. At the same time, the stirring shaft drives the second connecting sleeve 371 to rotate, and the rotating sleeve and the stirring shaft rotate relative to each other. At this time, the coil 372 can cut the magnetic flux lines to generate electromotive force, generate electrical energy, and the electric The energy can be supplied to the electromagnet 366, which is an AC electromagnet. After being energized, the electromagnet 366 can generate a magnetic force of repulsion from the second permanent magnet 3671, pushing the second friction plate 367 to contact the first friction plate 3631, and limiting the rotation of the first gear shaft 363 by the friction force. After the first gear shaft cannot rotate, the stirring shaft can drive the first connecting sleeve 361 to rotate synchronously, thereby driving the suction pipe 36 to rotate, and the liquid pump works to suck the slurry at the bottom of the dilution chamber into the introduction pipe 301. As the dilution work proceeds, after the red mud slurry is introduced, the liquid pump and the stirring motor continue to work. In the initial stage of stopping the introduction of the red mud slurry, due to the sedimentation at the bottom of the dilution chamber 30 The red mud slurry that has not been fully stirred and diluted is accumulated. Therefore, the concentration of the slurry pumped to the inlet pipe 301 by the liquid pump is still high at this time. At this time, the speed of the slurry passing through the leaking plate is still not high. A certain amount of material will accumulate on the upper surface of the leaking plate. The material leveling plate is still subject to greater resistance. The second connecting sleeve 371 and the stirring shaft 34 will still rotate relative to each other. At this time, the coil still cuts the magnetic flux lines to generate electrical energy, and the stirring shaft drives the suction pipe 36 to continue to rotate synchronously. As the work continues, the materials are mixed and diluted evenly, and the slurry at the bottom of the dilution chamber is also mixed evenly. The red mud slurry accumulated at the bottom of the dilution chamber is mixed evenly, and the comb teeth are no longer needed to comb at this time, and the evenly mixed slurry can be quickly discharged. The liquid flows through the leakage plate at a high speed, and no material will accumulate on the surface of the leakage plate. At this time, the reaction force of the slurry on the material leveling plate is very small. At this time, the resistance on the material leveling plate is smaller than the magnetic resistance between the coil and the first electromagnet. At this time, the second connecting sleeve 371 can rotate synchronously with the stirring shaft, and the electromagnet does not generate magnetism, and the thrust on the second friction plate disappears. At this time, the first gear shaft 363 can rotate freely. At this time, when the stirring shaft rotates, the first connecting sleeve 361 rotates relative to the stirring shaft, and no longer drives the first connecting sleeve 361 to rotate synchronously, thereby reducing the rotation resistance of the stirring shaft and reducing energy consumption. The stirring motor and the liquid pump continue to work for 5-10 minutes and then stop to complete the dilution work.

[0053] Specifically, in actual use, a detection device for detecting the second connecting sleeve 371 and the rotation speed can also be provided. When the red mud slurry is introduced through the introduction pipe 301, if the introduction speed of the red mud slurry is too fast, too much material will accumulate above the leakage plate, which will cause the material leveling plate to encounter too much resistance and be unable to rotate around the axis of the stirring shaft, thereby losing the material leveling effect. By providing a detection device, when the rotation speed of the stirring shaft is too low, the introduction speed of the red mud slurry is controlled to be reduced to ensure the material leveling effect of the material leveling plate.

[0054] The following is further described by specific examples: Example 1 Taking an alumina plant in Henan as an example, the mass percentage (%) of the chemical cost of red mud dissolved at low temperature in the plant is as follows: project <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> <![CDATA[SiO2]]> CaO <![CDATA[TiO2]]> <![CDATA[Na2O]]> A / S N / S C / S A / F Low temperature line red mud 20.80 53.85 5.19 3.74 3.63 1.75 4.01 0.34 0.72 0.39 The red mud was mixed with the evaporated seed fraction with an alkali concentration of 210g / l, and the solid content was 300 / l. Lime milk was added according to the total calcium-silicon ratio of the slurry of 0.80, and the temperature was raised to 270°C and reacted for 1 hour. The slurry was cooled to 80°C, then filtered, separated and washed. After the filter residue was dried and analyzed, its aluminum oxide content was 8.4% and the iron oxide content was 61.2%.

[0055] Example 2 Taking an alumina plant in Henan as an example, a high-temperature re-dissolution test was conducted on the low-temperature dissolution of red mud based on the low-temperature dissolution of ore. Through the experiment, the mass percentage (%) of the solid phase chemical components at each stage is as follows: name <![CDATA[SiO2]]> <![CDATA[Fe2O3]]> <![CDATA[Al2O3]]> CaO <![CDATA[TiO2]]> <![CDATA[K2O]]> <![CDATA[Na2O]]> Guinea Alumina Bauxite 2.17 24.19 46.5 0.05 2.37 0.03 0.05 Low temperature dissolved red mud 4.71 56.40 14.19 0.48 6.47 0.19 1.79 High temperature redissolution of red mud 4.97 60.02 9.25 2.20 6.40 0.24 3.23 Direct high temperature dissolution 5.35 57.91 10.45 2.70 6.22 0.20 3.25 It can be seen from the test data that the same ore can be effectively dissolved (recovered) from the low-temperature red mud by re-dissolving the red mud at high temperature after low-temperature dissolution, thereby improving the recovery rate of Guinea bauxite.

[0056] Example 3 Taking an alumina plant in Henan as an example, the plant used this technology to transform an original low-temperature production line, which was equipped with a high-temperature dissolution capacity of 270~280℃ after the transformation. On the basis of optimizing the pre-desiliconization and ore preparation conditions, the low-temperature dissolution solid content was increased from 230g / l to 260g / l (the preparation amount was reduced by 17%), and the dissolution was carried out at a low temperature of 140~145℃, and the dissolution red mud alumina content was 18%. After low-temperature dissolution, the red mud was adjusted by settling and washing liquid once to form a slurry with a solid content of 300-400g / l and ak of about 1.6. It was pumped into the high-temperature dissolution unit through a slurry pump and dissolved at 250~280℃. After dissolution, the content of monohydrate soft stone in low-temperature red mud was ≤0.5%, the average alumina content in red mud was 10.12%, the lowest monthly was 9.21%, and the average Fe2O3 content in red mud was above 61.36%.

[0057] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for increasing the iron oxide content in red mud, characterized in that: The following steps are involved: Batching: obtaining red mud slurry, diluting and separating the red mud slurry, adding additives to the underflow after dilution and separation, and adding mother liquor for secondary adjustment to obtain red mud slurry; High temperature dissolution; The red mud slurry is heated to a predetermined temperature T1 and maintained at the predetermined temperature T1 for 1-2 hours; Slurry filtration; dilution and separation of slurry after high temperature dissolution treatment.

2. A method for increasing the iron oxide content in red mud according to claim 1, characterized in that: The adding of an auxiliary agent to the underflow after dilution and separation comprises: The slurry is diluted and separated, and when the liquid-to-solid ratio of the underflow reaches 1: (1.8-2.2), additives are added to the underflow.

3. A method for increasing the iron oxide content in red mud according to claim 1 or 2, characterized in that: The additive is lime, and the addition ratio of lime is 1%-10%.

4. The method for increasing the iron oxide content in red mud according to claim 1, characterized in that: After the mother liquor is added for secondary adjustment, the caustic soda concentration of the red mud slurry is obtained to be 160 g / l-200 g / l.

5. The method for increasing the iron oxide content in red mud according to claim 1, characterized in that: The predetermined temperature T1 has a value range of 200°C-300°C.

6. The method for increasing the iron oxide content in red mud according to claim 1, characterized in that: The obtaining of red mud slurry comprises: First batching: control the caustic soda concentration in the slurry to 180 g / l -200 g / l; Pre-desiliconization: The slurry obtained from the first batch is heated to 90°C-100°C and maintained at this temperature for 12-16 hours for desiliconization treatment; Low temperature dissolution: add alkali solution to the ore pulp that has undergone pre-desiliconization dissolution treatment, keep it warm at 140℃-145℃ for 50 minutes-70 minutes to dissolve it, and obtain red mud slurry.

7. A method for increasing the iron oxide content in red mud according to claim 6, characterized in that: In the first batching, the concentration of sodium aluminate in the slurry is 200g / l-240g / l, and the solid content is 350g / l-450g / l.

8. The method for increasing the iron oxide content in red mud according to claim 6, characterized in that: In low temperature dissolution, after adding alkali solution to the slurry, the caustic soda concentration in the slurry is 190 g / l -200 g / l, and the solid content is 200 g / l -300 g / l.

9. The method for increasing the iron oxide content in red mud according to claim 1, characterized in that: In the batching step, diluting the red mud slurry includes: A predetermined amount of diluent is filled in the dilution chamber (30), and the low-temperature dissolved slurry is introduced into the dilution tank (3) through an introduction pipe (301) arranged at the top of the dilution chamber (30). The slurry enters the dilution chamber (30) from top to bottom through a material leveling plate (35), and is stirred by a stirring shaft to improve dilution efficiency.

10. A method for increasing the iron oxide content in red mud according to claim 9, characterized in that: Also includes: The liquid pump (311) works to suck and pump the material at the bottom of the dilution chamber (30) to the introduction pipe (301).

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