Device and method for extracting iron from red mud and preparing iron oxide red

Abstract

The purpose of this invention is to provide an apparatus and method for extracting iron from red mud and preparing ferric oxide red, belonging to the field of resource utilization technology. This invention uses hydrochloric acid to leach iron from red mud and then separates ferric chloride solution from the leachate through an extraction process. Subsequently, high-purity ferric oxide red is prepared through alkaline precipitation, washing, and calcination. By using the method of this invention, iron resources in red mud can be recovered, achieving the dual goals of resource utilization and environmentally friendly treatment.

Description

Technical Field

[0001] This invention belongs to the field of resource utilization technology, specifically relating to an apparatus and method for extracting iron from red mud and preparing iron oxide red. Background Technology

[0002] Red mud is a solid waste generated during alumina production. It gets its name from its red color due to its high iron oxide content. The yield of red mud is closely related to the ore grade and the alumina production process. Typically, producing 1 ton of alumina generates approximately 0.8-1.5 tons of red mud, and current domestic red mud reserves exceed 1.5 billion tons.

[0003] Red mud is a highly alkaline and corrosive hazardous substance. Its large-scale accumulation not only occupies land resources but also poses a serious threat to the surrounding environment, resulting in a huge ecological burden. With the gradual increase in domestic alumina production, the treatment and resource utilization of red mud has become one of the important issues that urgently need to be addressed in my country's environmental protection and comprehensive resource utilization field.

[0004] Red mud contains abundant elements such as iron, aluminum, calcium, silicon, sodium, and titanium, making it an important secondary resource with development value. Iron accounts for approximately 20-45% of the total weight of red mud. Therefore, extracting valuable elements from red mud can not only realize the utilization of iron resources and create economic benefits, but also effectively reduce the environmental pollution caused by red mud accumulation.

[0005] Against this backdrop, there is an urgent need for a simple and efficient technology to recover iron resources from red mud, so as to achieve the dual goals of resource utilization and environmentally friendly treatment. Summary of the Invention

[0006] The purpose of this invention is to provide a simple, efficient, and clean technique for extracting iron from red mud and preparing high-purity iron oxide red. This invention uses hydrochloric acid to leach iron from red mud, and then separates a ferric chloride solution from the leachate through an extraction process. Subsequently, high-purity iron oxide red is prepared through alkaline precipitation, washing, and calcination.

[0007] The second objective of this invention is to design an industrial-scale device for the extraction of iron from red mud and the preparation of iron oxide red, so as to improve the efficient recovery of iron from red mud and achieve stable, efficient and clean industrial applications.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] An apparatus for extracting iron from red mud and preparing iron oxide red includes a pulping device, a leaching device, an extraction device and a precipitation device;

[0010] The pulping device includes a cylinder made of steel. A water inlet is provided on one side of the top of the cylinder, and a screw conveyor is provided on the other side. A stirring motor is provided at the center of the top of the cylinder. The output end of the stirring motor is connected to a stirring paddle that extends into the cylinder. A discharge port is provided at the bottom of the cylinder.

[0011] One end of the screw conveyor is equipped with a motor, and the output end of the motor is connected to a screw rod. The bottom of the screw conveyor is equipped with a feed inlet, and the top is equipped with a discharge outlet, which is connected to the cylinder body.

[0012] Furthermore, the leaching device includes a leaching reactor, the top of which is provided with a top cover. The outer walls of the leaching reactor and the top cover are made of steel, and the inner walls are made of glass.

[0013] The leaching reactor has a feed inlet and a thermocouple inlet on both sides of its top. The thermocouple inlet is connected to a thermocouple that extends into the leaching reactor. The discharge port of the pulping device is connected to the feed inlet of the leaching reactor. The leaching reactor has a steam inlet on both sides of its upper end and a steam outlet on both sides of its bottom end. The leaching reactor has a discharge outlet and a condensate outlet at its bottom. The discharge outlet of the leaching reactor is connected to a plate and frame filter press. The outlet of the plate and frame filter press is connected to a leachate storage tank.

[0014] A cooling water outlet is provided on one side of the top cover, and a steel condensing device is provided above the top cover. A cooling water inlet is provided on one side of the top of the condensing device. The bottom of the condensing device is connected to the top cover through a pipe. A PVC condensing pipe is provided inside the condensing device, and both ends of the condensing pipe are connected to the inside of the leaching reactor.

[0015] A second stirring motor is located at the center of the top cover, and a second stirring paddle is connected to the output end of the second stirring motor.

[0016] Furthermore, the extraction apparatus includes an extraction tank, a back-extraction tank, several extraction settling tanks, and a back-extraction settling tank;

[0017] The top of the extraction tank is provided with a leachate inlet, and the outlet of the leachate storage tank is connected to the leachate inlet of the extraction tank; the top of the back-extraction tank is provided with a back-extractant inlet.

[0018] The bottom of the extraction tank is equipped with a mixed liquid outlet 1. The bottom of the mixed liquid outlet 1 is equipped with an electric valve and a raffinate outlet. The mixed liquid outlet 1 and the raffinate outlet are connected to the liquid inlet and outlet at the bottom of the extraction settling tank through an electric valve and an electric water pump. The liquid inlet and outlet are connected to an electric valve. The organic phase outlet on one side of the extraction settling tank is connected to the mixed liquid outlet 2 at the bottom of the back extraction tank through an electric valve and an electric water pump. The bottom of the mixed liquid outlet 2 is equipped with an electric valve and a back-extraction outlet. The mixed liquid outlet 2 and the back-extraction outlet are connected to the inlet at the bottom of the back extraction settling tank through an electric valve and an electric water pump. The inlet at the bottom of the back extraction settling tank is equipped with an electric valve.

[0019] Both the extraction tank and the back-extraction tank are equipped with a stirring motor three at the top, and the output end of the stirring motor three is connected to a stirring paddle three.

[0020] Furthermore, the precipitation device includes an alkali storage tank and a precipitation tank. The alkali storage tank has a precipitant inlet at the top and an alkali outlet at the bottom. The precipitation tank has an alkali discharge inlet and a back-extraction liquid inlet at the top and a precipitated suspension discharge outlet at the bottom. The back-extraction liquid inlet is connected to an electric pump. The back-extraction liquid discharge outlet of the extraction device is connected to the back-extraction liquid inlet of the precipitation device.

[0021] The alkali outlet of the alkali storage tank is connected to the alkali discharge inlet of the sedimentation tank through a pipeline. The pipeline is equipped with an electric valve and an electric alkali pump. A heat exchanger is installed on the outside of the pipeline. A steam inlet and a steam outlet are respectively provided above and below the heat exchanger.

[0022] The sedimentation tank is equipped with a thermocouple and a pH meter. The side wall of the sedimentation tank is equipped with a supernatant overflow port. The sedimentation suspension outlet at the bottom of the sedimentation tank is connected to an electric valve and an electric mud pump.

[0023] Both the alkali storage tank and the sedimentation tank are equipped with stirring motors at the top, and the output end of the stirring motors is connected to a stirring paddle.

[0024] A method for extracting iron from red mud and preparing iron oxide red includes the following steps:

[0025] Step 1, pulping: Add washing water and red mud to the cylinder of the pulping device at a ratio of 0.5-3L:1kg. Driven by the stirring motor, the first stirring paddle is stirred at a stirring rate of 500-3000r / min to prepare the red mud into a slurry. The stirring and pulping time is 5-30min.

[0026] The second step is leaching: the slurry-like red mud is pumped into the leaching reactor of the leaching device, and concentrated hydrochloric acid is added to the leaching reactor. The temperature inside the leaching reactor is raised to 50-105℃, and the mixture is stirred at a constant speed throughout the process. The leaching is carried out for 30-180 minutes to obtain a slurry mixture of leachate and leaching residue. The amount of concentrated hydrochloric acid added is 0.5-8L of concentrated hydrochloric acid with a mass fraction of 28-37% per 1kg of red mud.

[0027] The third step is filtration: After leaching is completed, the slurry mixture of the leachate obtained in the second step and the leachate residue is pumped to a plate and frame filter press using an acid-resistant mud pump. The leachate is obtained by squeezing and filtration, and then stored in a leachate storage tank for 1-12 hours.

[0028] Step 4, extraction: Use an acid-resistant pump to transfer the leachate from the leachate storage tank to the extraction tank. Add 0.5-5L of extractant per 1L of leachate. Adjust the extraction temperature to 10-65℃. Turn on the stirring motor 3 of the extraction tank and stir at a rate of 500-3000r / min. After stirring for 10-60min, the extraction operation is complete.

[0029] Step 5, settling and separation: The mixture after extraction in step 4 is transferred to the extraction settling tank and settling for 10-60 minutes. During the settling period, the temperature is kept at 25-60℃. After settling, the upper organic phase is extracted to obtain the iron-loaded organic phase; the lower aqueous phase, i.e., the raffinate, is discharged from the raffinate outlet. The remaining raffinate and organic phase in the settling tank are extracted.

[0030] Step 6, back-extraction: Pump the iron-loaded organic phase into the back-extraction tank, add 0.5-5L of back-extraction agent for every 1L of iron-loaded organic phase, the back-extraction temperature is 0-65℃, turn on the stirring motor three of the back-extraction tank, and stir the stirring paddle three of the back-extraction tank at a rate of 500-3000r / min. After stirring for 10-60min, the back-extraction operation is completed.

[0031] Step 7, settling and separation: The mixture after back-extraction in step 6 is transferred to the back-extraction settling tank and settling for 10-60 minutes. During the settling period, the temperature is kept at 25-60℃. After the settling period, the lower back-extraction liquid is discharged from the back-extraction liquid outlet. Then, the upper non-iron-loaded organic phase and a small amount of aqueous phase are pumped to the extraction settling tank for regeneration treatment before use.

[0032] Step 8, Neutralization and precipitation: Pump the back-extraction liquid obtained in step 7 to the precipitation tank, slowly add the alkaline precipitant into the precipitation tank, stir at a constant speed throughout the process, control the temperature of the precipitation process at 25-80℃, control the pH of the solution in the precipitation tank at 4.5-6.5, after the precipitation reaction is completed, let it settle for 5-30 minutes, remove the upper clear liquid, and the bottom is the precipitate slurry;

[0033] Step 9, settling: Use a mud pump to pump the slurry obtained in step 8 into the settling tank, let it stand for 1-72 hours, and then remove the supernatant.

[0034] Step 10, Filtration and Washing: After the upper clear liquid is extracted in step 9, the lower precipitate slurry is transported to a plate and frame filter press for filtration and washing to obtain ferric hydroxide precipitate and washing water.

[0035] Step 11, calcination: Place the ferric hydroxide precipitate in a kiln for calcination at a temperature of 500-1000℃ for 10-180 minutes. After calcination, ferric oxide red product is obtained.

[0036] Furthermore, the extractant described in step four comprises 15-65% by volume of extractant A, 1-25% by volume of extraction aid B, and 10-60% by volume of diluent C;

[0037] The extractant A includes one or more of the following: P507 (2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester), N235 (sec-octyl quaternary ammonium salt), TBP (tributyl phosphate), N1923 (sec-octyl dimethyl tertiary amine), P204 (di(2-ethylhexyl) phosphate), and TOPO (trioctylphosphine oxide);

[0038] Extraction aid B includes one or a mixture of DBP (dibutyl phosphate), TOP (trioctyl phosphate), isodecanol, palmitol, 1-octanol, 2-octanol, and isodecanol;

[0039] Diluent C includes one or more of sulfonated kerosene, toluene, xylene, octane, petroleum ether, and kerosene.

[0040] Furthermore, in step six, the back-extraction agent is composed of an acidic chloride solution with a pH of 3-6 and a concentration of 0.1-20 mol / L; the acidic chloride solution includes sodium chloride, calcium chloride, magnesium chloride, and potassium chloride.

[0041] Furthermore, the regeneration process described in step seven is as follows: the non-iron-supported organic phase is heated to 25-55°C, and the extractant is added according to the proportion described in step four and stirred evenly. The volume ratio of the extractant to the returned non-iron-supported organic phase is 0.001-0.2:1.

[0042] Further, the mass concentration of the precipitant in step eight is 1-500 g / L; the precipitant includes an aqueous solution or suspension prepared from one or more substances selected from NaOH, Ca(OH)2, CaO, MgO, Mg(OH)2, Na2CO3 and ammonia water.

[0043] The beneficial effects of this invention are as follows:

[0044] This invention provides a simple, efficient, and clean technique for extracting iron from red mud and preparing high-purity iron oxide red. The invention uses hydrochloric acid to leach iron from the red mud, and then separates a ferric chloride solution from the leachate through an extraction process. Subsequently, high-purity iron oxide red is prepared through alkaline precipitation, washing, and calcination.

[0045] This invention provides an industrial-scale device for the extraction of iron from red mud and the preparation of iron oxide red, thereby improving the efficient recovery of iron from red mud and achieving stable, efficient, and clean industrial applications. Attached Figure Description

[0046] Figure 1 This is a process flow diagram of the extraction of iron from red mud and the preparation of iron oxide red according to the present invention;

[0047] Figure 2 This is a schematic diagram of the pulping device of the present invention;

[0048] Figure 3 This is a schematic diagram of the leaching device of the present invention;

[0049] Figure 4 This is a schematic diagram of the extraction device of the present invention;

[0050] Figure 5 This is a schematic diagram of the precipitation device of the present invention;

[0051] Wherein: 1-Cylinder body; 2-Water inlet; 3-Agitator motor one; 4-Agitator paddle one; 5-Discharge port; 6-Motor; 7-Inlet one; 8-Screw conveyor; 9-Outlet one; 10-Thermocouple inlet; 11-Agitator motor two; 12-Inlet two; 13-Steam outlet; 14-Steam inlet; 15-Cooling water outlet; 16-Cooling water inlet; 17-Condensate outlet; 18-Outlet two; 19-Steam jacket; 20-Cooling water jacket; 21-Condensation device; 22-Condensate tube; 23-Thermocouple; 24-Agitator paddle two; 25-Steel outer shell; 26-Enameled inner wall; 27-Extraction tank; 28-Back-extraction tank; 29-Agitator motor three; 30-Agitator paddle three; 31-Leachate inlet; 32-Back-extraction agent inlet; 33-Mixed liquid 34-Mixed liquid outlet 2; 35-Extraction settling tank; 36-Liquid inlet / outlet; 37-Organic phase outlet; 38-Electric water pump; 39-Back-extraction liquid outlet; 40-Raffinate outlet; 41-Back-extraction settling tank; 42-Electric valve; 43-Alkali storage tank; 44-Precipitant inlet; 45-Stirring motor; 46-Stirring paddle; 47-Alkali outlet; 48-Settling tank; 49-Electric valve 1; 50-Electric alkali pump; 51-Electric mud pump; 52-Electric pump; 53-Electric valve 2; 54-Alkali outlet; 55-Supernatant overflow; 56-Back-extraction liquid inlet; 57-Precipitated suspension outlet; 58-Heat exchanger; 59-Steam inlet 1; 60-Steam outlet 1; 61-Thermocouple 1; 62-pH meter. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0053] An apparatus for extracting iron from red mud and preparing iron oxide red includes a pulping device, a leaching device, an extraction device and a precipitation device;

[0054] like Figure 2 As shown, the pulping device includes a cylinder 1 made of steel. A water inlet 2 is provided on one side of the top of the cylinder 1, and a screw conveyor 8 is provided on the other side. A stirring motor 3 is provided at the center of the top of the cylinder 1. The output end of the stirring motor 3 is connected to a stirring paddle 4 that extends into the cylinder 1. A discharge port 5 is provided at the bottom of the cylinder 1.

[0055] One end of the screw conveyor 8 is equipped with a motor 6, the output end of the motor 6 is connected to a screw rod, the bottom of the screw conveyor 8 is equipped with a feed inlet 7, the top is equipped with a discharge outlet 9, and the discharge outlet 9 is connected to the cylinder 1.

[0056] The instructions for using the pulping device are as follows: Red mud is loaded into the feed inlet 7 of the screw conveyor 8. Driven by the motor 6, the red mud is transported to the discharge outlet 9 and put into the cylinder 1. Washing water is pumped into the cylinder 1 through the water inlet 2. During the process of continuously feeding red mud and water into the cylinder 1, the stirring paddle 4 is slowly and uniformly stirred under the drive of the stirring motor 3. When the red mud and water in the cylinder 1 reach the rated quantity, the speed of the stirring motor 3 is slowly adjusted to high speed. After high-speed pulping and stirring for 5-30 minutes, the slurry is pumped out through the discharge outlet 5.

[0057] like Figure 3 As shown, the leaching device includes a leaching reactor, the top of which is provided with a top cover. The outer walls of the leaching reactor and the top cover are made of steel shell 25, and the inner walls are made of glass-lined inner walls 26.

[0058] The leaching reactor has a feed inlet 12 and a thermocouple inlet 10 on both sides of its top. The thermocouple inlet 10 is connected to a thermocouple 23 that extends into the leaching reactor. The discharge port 5 of the cylinder 1 of the pulping device is connected to the feed inlet 12 of the leaching reactor. The upper end of the leaching reactor has a steam inlet 14 on both sides and the bottom end has a steam outlet 13 on both sides. The bottom of the leaching reactor has a discharge port 18 and a condensate outlet 17. The discharge port 18 of the leaching reactor is connected to a plate and frame filter press, and the outlet of the plate and frame filter press is connected to a leachate storage tank.

[0059] A cooling water outlet 15 is provided on one side of the top cover, and a steel condensing device 21 is provided on the top of the top cover. A cooling water inlet 16 is provided on one side of the top of the condensing device 21. The bottom of the condensing device 21 is connected to the top cover through a pipe. A PVC condensing pipe 22 is provided inside the condensing device. Both ends of the condensing pipe 22 are connected to the inside of the leaching reactor.

[0060] A stirring motor 21 is located at the center of the top cover, and the output end of the stirring motor 21 is connected to a stirring paddle 24.

[0061] The operating instructions for the leaching device are as follows: Red mud slurry is pumped from the slurrying device to the inlet 12 of the leaching reactor and loaded into the reactor. Concentrated hydrochloric acid is also loaded into the leaching reactor through inlet 12. During the loading process, the stirring paddle 24 is slowly and uniformly stirred under the drive of the stirring motor 11. Once the hydrochloric acid and red mud slurry in the leaching reactor reach the predetermined quantity, the stirring motor 11 is adjusted to the predetermined speed. Simultaneously, steam is introduced into the steam jacket 19 of the leaching reactor through the steam inlet 14, heating the material by heating the enamel inner wall 26. The released steam is discharged through the steam outlet 13, and the condensate generated by the steam heating the enamel inner wall 26 is discharged through the condensate outlet 17. Thermocouple 23 is used to monitor the solution temperature in the leaching reactor. When the temperature reaches the preset temperature, the amount of steam input to the steam inlet 14 is controlled to ensure constant temperature leaching. The cooling water jacket 20 of the top cover is connected to the condenser 21. Cooling water enters through the cooling water inlet 16 and circulates to the cooling water outlet 15 before being discharged. The condenser 21 is lined with PVC condenser pipes 22, which are connected to the interior of the leaching reactor. During leaching, the cooling water circulation system is turned on, and cold water enters through the cooling water inlet 16 and exits through the cooling water outlet 15. Hydrochloric acid vapor in the leaching reactor enters the condenser pipes 22, condenses there, and then flows back into the leaching reactor. After leaching is complete, the mixed liquid is discharged through the discharge port 18 and transported to the next process.

[0062] A schematic diagram of the extraction device structure for the extraction-separation-back-extraction-separation process is shown below. Figure 4 As shown, it includes an extraction tank 27, a back-extraction tank 28, several extraction settling tanks 35 and a back-extraction settling tank 41;

[0063] The top of the extraction tank 27 is provided with a leachate inlet 31, and the outlet of the leachate storage tank is connected to the leachate inlet 31 of the extraction tank 27; the top of the back extraction tank 28 is provided with a back extractant inlet 32.

[0064] The bottom of the extraction tank 27 is provided with a mixed liquid outlet 33. The bottom of the mixed liquid outlet 33 is provided with an electric valve 42 and a raffinate outlet 40. The mixed liquid outlet 33 and the raffinate outlet 40 are connected to the liquid inlet 36 at the bottom of the extraction settling tank 35 through the electric valve 42 and the electric water pump 38. The liquid inlet 36 is connected to the electric valve 42. The organic phase outlet 37 on one side of the extraction settling tank 35 is connected to the mixed liquid outlet 34 at the bottom of the back extraction tank 28 through the electric valve 42 and the electric water pump 38. The bottom of the mixed liquid outlet 34 is provided with an electric valve 42 and a back extraction liquid outlet 39. The mixed liquid outlet 34 and the back extraction liquid outlet 39 are connected to the inlet at the bottom of the back extraction settling tank 41 through the electric valve 42 and the electric water pump 38. The inlet at the bottom of the back extraction settling tank 41 is provided with an electric valve 42.

[0065] Both the top of the extraction tank 27 and the reverse extraction tank 28 are equipped with a stirring motor 3 29, and the output end of the stirring motor 3 29 is connected to a stirring paddle 3 30.

[0066] The operating instructions for the extraction device are as follows: The leachate is added to the extraction tank 27 through the leachate inlet 31. After regeneration treatment in the extraction settling tank 35, the extractant, driven by the electric water pump 38, enters the extraction tank 27 through the liquid inlet / outlet 36 and the extraction tank mixed liquid outlet 33. The electric valve 42 is closed, and the stirring motor 29 is turned on to drive the stirring paddle 30 for extraction. After extraction, the mixed liquid in the extraction tank 27 enters the extraction settling tank 35 through the mixed liquid outlet 33 and the liquid inlet / outlet 36 for a settling separation process. After settling, the upper iron-loaded organic phase is first transported to the back-extraction tank 28 through the organic phase outlet 37 and the mixed liquid outlet 34, and then the lower aqueous phase is discharged through the liquid inlet / outlet 36 and the raffinate outlet 40. After the iron-loaded organic phase is loaded into the back-extraction tank 28, the back-extraction agent is transported into the back-extraction tank 28 through the back-extraction agent inlet 32. The stirring motor 29 of the back-extraction tank 28 is turned on, and back-extraction is carried out under the stirring of the stirring paddle 30. After the back-extraction is completed, the mixed liquid enters the back-extraction settling tank 41 through the mixed liquid outlet 34 and the liquid inlet / outlet at the bottom of the back-extraction settling tank. After standing for a period of time, the lower aqueous phase, i.e., the back-extraction liquid, is first released from the back-extraction settling tank 41. The back-extraction liquid is discharged through the liquid inlet / outlet at the bottom of the back-extraction settling tank 41 and the back-extraction liquid outlet 39. Then, the upper organic phase is pumped into the extraction settling tank 35 for regeneration treatment and is ready for use.

[0067] The precipitation device is as follows Figure 5 As shown, it includes an alkali storage tank 43 and a precipitation tank 48. The top of the alkali storage tank 43 is provided with a precipitant inlet 44 and the bottom is provided with an alkali outlet 47. The top of the precipitation tank 48 is provided with an alkali discharge inlet 54 and a back-extraction liquid inlet 56, and the bottom is provided with a precipitate suspension discharge outlet 57. The back-extraction liquid inlet 56 is connected to an electric pump 52. The back-extraction liquid outlet 39 of the extraction device is connected to the back-extraction liquid inlet 56 of the precipitation device.

[0068] The alkali outlet 47 of the alkali storage tank 43 is connected to the alkali discharge inlet 54 of the sedimentation tank 48 through a pipe. The pipe is equipped with an electric valve 49 and an electric alkali pump 50. A heat exchanger 58 is provided on the outside of the pipe. A steam inlet 59 and a steam outlet 60 are provided above and below the heat exchanger 58, respectively.

[0069] The sedimentation tank 48 is equipped with a thermocouple 61 and a pH meter 62. The side wall of the sedimentation tank 48 is equipped with a supernatant overflow port 55. The sedimentation suspension outlet 57 at the bottom of the sedimentation tank 48 is connected to an electric valve 53 and an electric mud pump 51.

[0070] Both the alkali storage tank 43 and the sedimentation tank 48 are equipped with a stirring motor 45 at the top, and the output end of the stirring motor 45 is connected to a stirring paddle 46.

[0071] The instructions for using the precipitation device are as follows: The alkaline precipitant is discharged into the alkaline storage tank 43 through the precipitant inlet 44. Driven by the stirring motor 45, the stirring paddle 46 slowly and uniformly stirs the precipitant solution to ensure uniformity and prevents sedimentation. The back-extraction solution obtained from the back-extraction is pumped into the precipitation tank 48 through the back-extraction solution inlet 56. The stirring motor is turned on, driving the stirring paddle to stir at a uniform speed. During the precipitation process, thermocouple 61 is used to monitor the temperature inside the precipitation tank 48, controlling the amount of steam flowing through the heat exchanger 58 and the temperature of the precipitant flowing in, thereby controlling the reaction temperature inside the precipitation tank 48. Steam flows in through the steam inlet 59, and condensate and low-temperature steam flow out through the steam outlet 60. During the precipitation process, pH meter 62 is used to monitor the pH value of the solution. The electric valve 49 and the electric alkaline pump 50 are controlled to slowly add the precipitant through the alkaline discharge inlet 54 until the solution pH reaches the predetermined value. After the pH stabilizes, open the electric valve 53, and the mixed slurry is discharged through the sedimentation suspension outlet 57 under the drive of the electric mud pump 51.

[0072] Example 1

[0073] The process flow diagram for preparing high-purity iron oxide red in this embodiment is as follows: Figure 1 As shown in Table 1, the specific composition of the red mud used is as shown in the table.

[0074] Table 1. Chemical composition of the red mud used in Example 1, mass fraction %

[0075]

[0076] The preparation process is as follows:

[0077] (1) Turn on the stirring motor 3 and adjust the stirring paddle 4 to slow speed. While using the screw conveyor 8 to add 100kg of red mud with a moisture content of 1% into the tank 1, add 50L of washing water into the tank 1 through the water inlet 2. After all the water is added, adjust the stirring motor 3 to fast speed and pulverize at high speed for 15 minutes.

[0078] (2) Turn on the stirring motor 11 of the leaching reactor, adjust the speed of the stirring paddle 24 to slow speed, use the mud pump to pump the mud-like red mud in the tank 1 to the leaching reactor through the feed port 12, and then add 250L of 37% concentrated hydrochloric acid through the feed port 12 while stirring. Adjust the stirring motor 11 to fast speed, then turn on the cooling water circulation of the condenser 21, and then input steam into the steam jacket 19 through the steam inlet 14. Under the monitoring of the thermocouple 23, control the solution temperature to 105℃ and leach for 1.5 hours.

[0079] (3) The leached slurry is pumped to a plate and frame filter press for filtration and separation. After filtration, it is washed once with 168L of washing water. The filtrate and washing liquid are mixed to obtain 366.69L of leachate. The iron leaching recovery rate is 95%, and the iron concentration in the leachate is 31.88g / L.

[0080] (4) 366.69 L of leachate at 50 °C is pumped into extraction tank 27 through leachate inlet 31. The extractant in extraction settling tank 35 is pumped into extraction tank 27 by electric water pump 38. The amount of extractant added is 733.38 L. The electric valve 42 at the bottom of extraction tank 27 is closed, and the stirring motor 39 of extraction tank 27 is turned on to drive the stirring paddle 30 for extraction. The extraction is completed after stirring for 30 minutes. Here, the volume ratio of extractant A in the extractant is 45%, the volume ratio of extraction aid B is 10%, and the volume ratio of diluent C is 45%. Extractant A is composed of N1923 and TBP in a 1:1 ratio, extraction aid B is 2-octanol, and diluent C is sulfonated kerosene.

[0081] (5) After the extraction is completed in the previous step, the mixture is transported to the extraction settling tank 35 and left to stand for 40 minutes. During the standing period, the temperature is kept at 50°C. After the standing period, the upper organic phase is extracted through the organic phase outlet 37 to obtain 731.58L of iron-loaded organic phase.

[0082] (6) Pump 731.58L of iron-loaded organic phase into the back-extraction tank 28, and add 730L of back-extraction agent aqueous solution at 60℃ through the back-extraction agent inlet 32. The pH of the back-extraction agent aqueous solution is 4, and the concentrations of sodium chloride and calcium chloride in the back-extraction agent are 2mol / L and 3mol / L, respectively. Turn on the stirring motor 39 and the stirring paddle 30 of the back-extraction tank 28 at high speed. After stirring for 30 minutes, the back-extraction operation is completed.

[0083] (7) The mixture after the previous back-extraction is transferred to the back-extraction settling tank 41 and left to stand for 40 minutes. During the standing period, the temperature is kept at 50°C. After the standing period, the lower back-extraction liquid is discharged through the back-extraction liquid outlet 39 to obtain 725.65L of back-extraction liquid. Then, the upper non-iron-loaded organic phase and the residual aqueous phase are pumped to the extraction settling tank 35 for regeneration treatment and then put into use. During the regeneration treatment, extractant A, extraction aid B and diluent C are added according to the ratio of extractant in step 4 and stirred evenly. The total volume ratio of the three solvents to the volume of the returned non-iron-loaded organic phase is 0.005:1.

[0084] (8) The back-extraction solution obtained in step 7 is pumped to the precipitation tank 48. The alkaline precipitant is slowly transported from the alkaline storage tank 43 to the precipitation tank 48. The stirring paddle 46 in the precipitation tank 48 is stirred at a constant speed throughout the process. The system temperature is monitored by thermocouple 61, and the amount of steam introduced into the heat exchanger 58 is controlled to maintain the precipitation temperature at 50°C. The pH of the system is monitored by pH meter 62, and the flow rate and velocity of the alkaline precipitant are controlled. When the pH of the solution in the precipitation tank 48 reaches 5.5, the precipitation reaction ends. After settling for 15 minutes, the supernatant is extracted through the supernatant overflow port 55. The precipitant is a suspension prepared from NaOH and Ca(OH)2, with a molar ratio of NaOH to Ca(OH)2 of 1:5. The mass concentration of NaOH is 20 g / L, and the mass concentration of Ca(OH)2 is 185 g / L.

[0085] (9) Use electric mud pump 51 to pump the precipitated slurry obtained in the previous step from the precipitated suspension outlet 57 to the sedimentation tank. After standing for 48 hours, the upper clear liquid is extracted.

[0086] (10) After the upper clear liquid is extracted in step nine, the lower sediment slurry is transported to a plate and frame filter press for filtration and washing. 43.67 kg of ferric hydroxide precipitate filter cake with a water content of 51% is obtained and the washing water consumption is 89.08 L.

[0087] (11) The precipitated filter cake of ferric hydroxide was placed in a kiln for calcination at a temperature of 900℃ for 120 minutes. After calcination, 16.65 kg of ferric oxide red product was obtained, with a ferric oxide mass fraction of 95.3% and an iron recovery rate of 93.12%.

[0088] Example 2

[0089] The process flow diagram for preparing high-purity iron oxide red in this embodiment is as follows: Figure 1 As shown in Table 2, the specific composition of the red mud used is as shown in the table.

[0090] Table 2. Chemical composition of the red mud used in Example 2, mass fraction %

[0091]

[0092] The preparation process is as follows:

[0093] (1) Turn on the stirring motor 3 and adjust the stirring paddle 4 to slow speed. While using the screw conveyor 8 to add 100kg of red mud with a moisture content of 2% into the tank 1, add 80L of washing water into the tank 1 through the water inlet 2. After all the water is added, adjust the stirring motor 3 to fast speed and pulverize at high speed for 15 minutes.

[0094] (2) Turn on the stirring motor 11 of the leaching reactor, adjust the speed of the stirring paddle 24 to slow speed, use the mud pump to pump the mud-like red mud in the tank 1 to the leaching reactor through the feed port 12, and then add 320L of 35% concentrated hydrochloric acid through the feed port 12 while stirring. Adjust the stirring motor 11 to fast speed, then turn on the cooling water circulation of the condenser 21, and then input steam into the steam jacket 19 through the steam inlet 14. Under the monitoring of the thermocouple 23, control the solution temperature to 100℃ and leach for 2 hours.

[0095] (3) The leached slurry is pumped to a plate and frame filter press for filtration and separation. After filtration, it is washed once with 182L of washing water. The filtrate and washing liquid are mixed to obtain 452.01L of leachate. The iron leaching recovery rate is 96.2%, and the iron concentration in the leachate is 23.29g / L.

[0096] (4) 452.01L of leachate at 50℃ is pumped into extraction tank 27 through leachate inlet 31. The extractant in extraction settling tank 35 is pumped into extraction tank 27 by electric water pump 38. The amount of extractant added is 460L. The electric valve 42 at the bottom of extraction tank 27 is closed, and the stirring motor 39 of extraction tank 27 is turned on to drive the stirring paddle 30 for extraction. The extraction is completed after stirring for 30 minutes. Here, the volume ratio of extractant A in the extractant is 52%, the volume ratio of extraction aid B is 8%, and the volume ratio of diluent C is 40%. Extractant A is composed of N235 and TBP in a 5:1 ratio, extraction aid B is composed of 2-octanol and isodecanol in a 2:1 ratio, and diluent C is sulfonated kerosene.

[0097] (5) After the extraction is completed in the previous step, the mixture is transported to the extraction settling tank 35 and left to stand for 30 minutes. During the standing period, the temperature is kept at 45°C. After the standing period, the upper organic phase is extracted through the organic phase outlet 37 to obtain 456.6L of iron-loaded organic phase.

[0098] (6) Pump 456.6L of iron-loaded organic phase into the back-extraction tank 28, and add 460L of back-extraction agent aqueous solution at 50℃ through back-extraction agent inlet 32. The pH of the back-extraction agent aqueous solution is 5, and the concentrations of sodium chloride and calcium chloride in the back-extraction agent are 1mol / L and 4mol / L, respectively. Turn on the stirring motor 39 and the stirring paddle 30 of the back-extraction tank 28 at high speed. After stirring for 20 minutes, the back-extraction operation is completed.

[0099] (7) The mixture after the previous back-extraction is transferred to the back-extraction settling tank 41 and left to stand for 30 minutes. During the standing period, the temperature is kept at 45°C. After the standing period, the lower back-extraction liquid is discharged through the back-extraction liquid outlet 39 to obtain 457.5L of back-extraction liquid. Then, the upper non-iron-loaded organic phase and the residual aqueous phase are pumped to the extraction settling tank 35 for regeneration treatment and then put into use. During the regeneration treatment, extractant A, extraction aid B and diluent C are added according to the ratio of extractant in step 4 and stirred evenly. The total volume ratio of the three solvents to the volume of the returned non-iron-loaded organic phase is 0.003:1.

[0100] (8) The back-extraction solution obtained in step 7 is pumped to the precipitation tank 48. The alkaline precipitant is slowly transported from the alkaline storage tank 43 to the precipitation tank 48. The stirring paddle 46 in the precipitation tank 48 is stirred at a constant speed throughout the process. The system temperature is monitored by thermocouple 61, and the amount of steam introduced into the heat exchanger 58 is controlled to maintain the precipitation temperature at 60°C. The pH of the system is monitored by pH meter 62, and the flow rate and velocity of the alkaline precipitant are controlled. When the pH of the solution in the precipitation tank 48 reaches 5.0, the precipitation reaction ends. After settling for 15 minutes, the supernatant is extracted through the supernatant overflow port 55. The precipitant is a suspension prepared from NaOH and Ca(OH)2, with a molar ratio of NaOH to Ca(OH)2 of 1:9. The mass concentration of NaOH is 4 g / L, and the mass concentration of Ca(OH)2 is 66.6 g / L.

[0101] (9) Use electric mud pump 51 to pump the precipitated slurry obtained in the previous step from the precipitated suspension outlet 57 to the sedimentation tank. After standing for 48 hours, the upper clear liquid is extracted.

[0102] (10) After the upper clear liquid is extracted in step nine, the lower sediment slurry is transported to a plate and frame filter press for filtration and washing to obtain 36.5 kg of ferric hydroxide precipitate filter cake with a water content of 46% and a washing water volume of 78.84 L.

[0103] (11) The precipitated filter cake of ferric hydroxide was placed in a kiln for calcination at a temperature of 950°C for 100 minutes. After calcination, 15.3 kg of ferric oxide red product was obtained, with a ferric oxide mass fraction of 96.1% and an iron recovery rate of 94.07%.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for extracting iron from red mud and producing red iron oxide, characterized by: It includes a pulping device, a leaching device, an extraction device, and a sedimentation device; The pulping device includes a cylinder (1) made of steel material. A water inlet (2) is provided on one side of the top of the cylinder (1), and a screw conveyor (8) is provided on the other side. A stirring motor (3) is provided at the center of the top of the cylinder (1). The output end of the stirring motor (3) is connected to a stirring paddle (4) that extends into the cylinder (1). A discharge port (5) is provided at the bottom of the cylinder (1). One end of the screw conveyor (8) is equipped with a motor (6), the output end of the motor (6) is connected to a screw rod, the bottom of the screw conveyor (8) is equipped with a feed inlet (7), the top is equipped with a discharge outlet (9), and the discharge outlet (9) is connected to the cylinder (1). The leaching device includes a leaching reactor with a top cover. The outer walls of the leaching reactor and the top cover are made of steel (25), and the inner walls are made of glass (26). The top two sides of the leaching reactor are respectively provided with a second feed inlet (12) and a thermocouple inlet (10). The thermocouple inlet (10) is connected to a thermocouple (23) that extends into the leaching reactor. The discharge port (5) of the cylinder (1) of the pulping device is connected to the second feed inlet (12) of the leaching reactor. The upper two sides of the leaching reactor are respectively provided with a steam inlet (14) and the lower two sides are respectively provided with a steam outlet (13). The bottom of the leaching reactor is provided with a second discharge port (18) and a condensate outlet (17). The second discharge port (18) of the leaching reactor is connected to a plate and frame filter press. The outlet of the plate and frame filter press is connected to a leachate storage tank. A cooling water outlet (15) is provided on one side of the top cover, and a steel condensing device (21) is provided above the top cover. A cooling water inlet (16) is provided on one side of the top of the condensing device (21). The bottom of the condensing device is connected to the top cover through a pipe. A PVC condensing pipe (22) is provided inside the condensing device. Both ends of the condensing pipe (22) are connected to the inside of the leaching reactor. The center of the top cover is equipped with a stirring motor 2 (11), and the output end of the stirring motor 2 (11) is connected to a stirring paddle 2 (24). The extraction apparatus includes an extraction tank (27), a back-extraction tank (28), several extraction settling tanks (35) and a back-extraction settling tank (41). The top of the extraction tank (27) is provided with an extractant inlet (31), and the outlet of the extractant storage tank is connected to the extractant inlet (31) of the extraction tank (27); the top of the back-extraction tank (28) is provided with a back-extractant inlet (32). The bottom of the extraction tank (27) is provided with a mixed liquid outlet (33), and the bottom of the mixed liquid outlet (33) is provided with an electric valve (42) and a raffinate outlet (40). The mixed liquid outlet (33) and the raffinate outlet (40) are connected to the liquid inlet / outlet (36) at the bottom of the extraction settling tank (35) through the electric valve (42) and the electric water pump (38). The liquid inlet / outlet (36) is connected to the electric valve (42). The organic phase outlet (36) on one side of the extraction settling tank (35) is provided with a mixed liquid outlet (33). 7) The mixture outlet (34) at the bottom of the back-extraction tank (28) is connected to the electric valve (42) and the electric water pump (38). The bottom of the mixture outlet (34) is equipped with an electric valve (42) and a back-extraction outlet (39). The mixture outlet (34) and the back-extraction outlet (39) are connected to the bottom inlet of the back-extraction settling tank (41) through the electric valve (42) and the electric water pump (38). The bottom inlet of the back-extraction settling tank (41) is equipped with an electric valve (42). Both the top of the extraction tank (27) and the back extraction tank (28) are equipped with a stirring motor three (29), and the output end of the stirring motor three (29) is connected to a stirring paddle three (30). The precipitation device includes an alkali storage tank (43) and a precipitation tank (48). The top of the alkali storage tank (43) is provided with a precipitant inlet (44) and the bottom is provided with an alkali outlet (47). The top of the precipitation tank (48) is provided with an alkali discharge inlet (54) and a back-extraction liquid inlet (56), and the bottom is provided with a precipitated suspension discharge outlet (57). The back-extraction liquid inlet (56) is connected to an electric pump (52). The back-extraction liquid discharge outlet (39) of the extraction device is connected to the back-extraction liquid inlet (56) of the precipitation device. The alkali outlet (47) of the alkali storage tank (43) is connected to the alkali discharge inlet (54) of the sedimentation tank (48) through a pipe. An electric valve (49) and an electric alkali pump (50) are provided on the pipe. A heat exchanger (58) is provided on the outside of the pipe. A steam inlet (59) and a steam outlet (60) are provided above and below the heat exchanger (58), respectively. The sedimentation tank (48) is equipped with a thermocouple (61) and a pH meter (62). The side wall of the sedimentation tank (48) is equipped with a supernatant overflow port (55). The sedimentation suspension outlet (57) at the bottom of the sedimentation tank (48) is connected to an electric valve (53) and an electric mud pump (51). Both the top of the alkali storage tank (43) and the sedimentation tank (48) are equipped with a stirring motor (45), and the output end of the stirring motor (45) is connected to a stirring paddle (46).

2. A method for extracting iron from red mud and preparing iron oxide red using the apparatus described in claim 1, characterized in that: Includes the following steps: Step 1, pulping: Washing water and red mud are loaded into the cylinder (1) of the pulping device at a ratio of 0.5-3L:1kg. The stirring paddle (4) is driven by the stirring motor (3) at a stirring rate of 500-3000r / min to prepare the red mud into a slurry. The stirring and pulping time is 5-30min. The second step is leaching: the slurry-like red mud is pumped into the leaching reactor of the leaching device, and concentrated hydrochloric acid is added to the leaching reactor. The temperature inside the leaching reactor is raised to 50-105℃, and the mixture is stirred at a constant speed throughout the process. The leaching is carried out for 30-180 minutes to obtain a slurry mixture of leachate and leaching residue. The amount of concentrated hydrochloric acid added is 0.5-8L of concentrated hydrochloric acid with a mass fraction of 28-37% per 1kg of red mud. The third step is filtration: After leaching is completed, the slurry mixture of the leachate obtained in the second step and the leachate residue is pumped to a plate and frame filter press using an acid-resistant mud pump. The leachate is obtained by squeezing and filtration, and then stored in a leachate storage tank for 1-12 hours. Step 4, extraction: Use an acid-resistant pump to transport the leachate from the leachate storage tank to the extraction tank (27), add 0.5-5L of extractant per 1L of leachate, adjust the extraction temperature to 10-65℃, turn on the stirring motor 3 (29) of the extraction tank (27), stir at a rate of 500-3000r / min, stir for 10-60min, and the extraction operation is completed; Step 5, settling and separation: The mixture after extraction in step 4 is transported to the extraction settling tank (35) and settling for 10-60 minutes. During the settling period, the temperature is kept at 25-60℃. After settling, the upper organic phase is extracted to obtain the iron-loaded organic phase; the lower aqueous phase, i.e. the raffinate, is discharged from the raffinate outlet (40). The remaining raffinate and organic phase in the extraction settling tank (35) are separated. Step 6, back-extraction: Pump the iron-loaded organic phase into the back-extraction tank (28), add 0.5-5L of back-extraction agent for every 1L of iron-loaded organic phase, the back-extraction temperature is 0-65℃, turn on the stirring motor three (29) of the back-extraction tank (28), and stir the stirring paddle three (30) of the back-extraction tank (28) at a rate of 500-3000r / min. After stirring for 10-60min, the back-extraction operation is completed. Step 7, settling and separation: The mixture after back-extraction in step 6 is transported to the back-extraction settling tank (41) and settling for 10-60 minutes. During the settling period, the temperature is kept at 25-60℃. After the settling period, the lower back-extraction liquid is discharged from the back-extraction liquid outlet (39), and then the upper non-iron-loaded organic phase and a small amount of aqueous phase are pumped to the extraction settling tank (35) for regeneration treatment and then put into use. Step 8, neutralization and precipitation: Pump the back-extraction liquid obtained in step 7 to the precipitation tank (48), slowly add the alkaline precipitant into the precipitation tank (48), stir at a constant speed throughout the process, control the temperature of the precipitation process to 25-80℃, control the pH of the solution in the precipitation tank (48) to 4.5-6.5, after the precipitation reaction is completed, let it settle for 5-30 minutes, remove the upper clear liquid, and the bottom is the precipitate slurry; Step 9, settling: Use a mud pump to pump the slurry obtained in step 8 into the settling tank, let it stand for 1-72 hours, and then remove the supernatant. Step 10, Filtration and Washing: After the upper clear liquid is extracted in step 9, the lower precipitate slurry is transported to a plate and frame filter press for filtration and washing to obtain ferric hydroxide precipitate and washing water. Step 11, calcination: Place the ferric hydroxide precipitate in a kiln for calcination at a temperature of 500-1000℃ for 10-180 minutes. After calcination, ferric oxide red product is obtained. The extractant mentioned in step four includes 15-65% by volume of extractant A, 1-25% by volume of extraction aid B, and 10-60% by volume of diluent C; The extractant A includes one or more of the following: P507 (2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester), N235 (sec-octyl quaternary ammonium salt), TBP (tributyl phosphate), N1923 (sec-octyl dimethyl tertiary amine), P204 (di(2-ethylhexyl) phosphate), and TOPO (trioctylphosphine oxide); Extraction aid B includes one or a mixture of DBP (dibutyl phosphate), TOP (trioctyl phosphate), isodecanol, palmitol, 1-octanol, 2-octanol, and isodecanol; Diluent C includes one or more of sulfonated kerosene, toluene, xylene, octane, petroleum ether, and kerosene; The mass concentration of the precipitant mentioned in step 8 is 1-500 g / L; the precipitant includes an aqueous solution or suspension prepared from one or more substances selected from NaOH, Ca(OH)2, CaO, MgO, Mg(OH)2, Na2CO3 and ammonia water.

3. The method for extracting iron from red mud and preparing iron oxide red according to claim 2, characterized in that: The back-extraction agent mentioned in step six is ​​composed of an acidic solution of chloride salts, the pH of the back-extraction agent is 3-6, and the concentration of the acidic solution of chloride salts is 0.1-20 mol / L; the acidic solution of chloride salts includes sodium chloride, calcium chloride, magnesium chloride and potassium chloride.

4. The method for extracting iron from red mud and preparing iron oxide red according to claim 2, characterized in that: The regeneration process described in step seven is as follows: heat the non-iron-supported organic phase to 25-55℃, add the extractant according to the ratio in step four, and stir evenly. The volume ratio of the extractant to the returned non-iron-supported organic phase is 0.001-0.2:1.

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