A method and device for recovering iron from red mud

Abstract

The present invention discloses a method and apparatus for recovering iron from red mud. The specific process is as follows: red mud slurry in the red mud pipeline of the alumina workshop is mineralized, the mineralized red mud slurry is fed into an electrolysis system for electrolysis, the caustic soda concentration in the electrolyte is controlled to be 5-25 mol / L, the electrolysis voltage is between 1.3V and 1.6V, and the red mud slurry temperature in the electrolysis system is maintained between 110-120°C. The electrolysis is stopped after 2-8 hours, and the iron on the cathode of the electrolysis system is stripped and disposed of to obtain a high-purity iron product. Using the present invention, the iron product recovered from red mud is higher in purity, with lower energy consumption and better environmental protection.

Description

Technical Field

[0001] The present invention relates to the technical field of red mud recovery and utilization, and in particular to a method and device for recovering iron from red mud. Background Art

[0002] In 2021, China produced 77.575 million tons of alumina, accounting for approximately 55% of global alumina production, maintaining its position as the world's largest alumina producer. Based on the calculation that 1.5 tons of red mud are emitted for every ton of alumina produced, China generated approximately 120 million tons of red mud in 2021.

[0003] As domestic bauxite reserves decrease and grades decline, aluminum production capacity based primarily on domestic diaspore ore is gradually declining, while aluminum production capacity based on imported, high-iron gibbsite ore is increasing. It is estimated that more than half of the newly added red mud in China is high-iron red mud (T.Fe ≥ 30%). In recent years, my country's steel production has exceeded 1 billion tons, and its dependence on foreign iron ore has exceeded 80%, making the search for new sources of iron ore imperative. Although the iron grade of red mud is relatively low, given the huge amount of red mud discharged, high-iron red mud is considered a substitute for low-grade iron ore.

[0004] Iron recovery from red mud is one of the key approaches to reducing red mud production. Domestic and international researchers have conducted extensive research on iron separation from red mud. The main iron separation approaches include physical separation, pyrometallurgy, and hydrometallurgy. Table 1 summarizes the advantages and disadvantages of these different approaches.

[0005] Table 1

[0006]

[0007]

[0008] Existing iron recovery technologies from red mud suffer from issues such as low iron concentrate grade, making them difficult for the steel industry to utilize. Other issues include high production and maintenance costs and insufficient energy efficiency, hindering industrialization and promotion. Furthermore, these technologies suffer from poor technical efficiency and economic viability due to lengthy technical processes, high acid consumption, and difficulty in product separation and purification. Existing technologies have failed to effectively utilize the iron resources in red mud, resulting in a red mud utilization rate of less than 5%.

[0009] Therefore, developing a new method to recover iron from red mud, achieving efficient and low-cost recovery of iron while ensuring the high purity of the recovered iron is of great significance to the disposal and utilization of iron-containing solid wastes such as red mud. Summary of the Invention

[0010] In view of the shortcomings of the existing technology, the present invention aims to provide a method and device for recovering iron from red mud, which has a short process, high reaction efficiency, high product purity and significant economic benefits.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] A method for recovering iron from red mud, the specific process is:

[0013] The red mud slurry in the red mud pipeline of the alumina workshop is mineralized and sent to the electrolysis system for electrolysis. The caustic soda concentration in the electrolyte is controlled at 5-25 mol / L, the electrolysis voltage is between 1.3v-1.6v, and the temperature of the red mud slurry in the electrolysis system is maintained between 110-120°C. The electrolysis is stopped after 2-8 hours, and the iron on the cathode of the electrolysis system is stripped to obtain a high-purity iron product.

[0014] The present invention also provides a device for implementing the above method, comprising a red mud mineralization system, a metering feeding system, an electrolysis system, and an iron stripping system connected in sequence; the device also comprises a heating medium storage tank, an alkali solution storage tank, and a gas collection system, and the heating medium storage tank, alkali solution storage tank, and gas collection system are connected to the electrolysis system; the heating medium storage tank is used to store the heating medium and transport the heating medium to the electrolysis system, the alkali solution storage tank is used to store the caustic alkali solution and transport the caustic alkali solution to the electrolysis system, and the gas collection system is used to collect and process the exhaust gas discharged from the electrolysis system.

[0015] Furthermore, the electrolysis system uses an anode, a cathode and a reference electrode to form a three-electrode system, and is powered by a DC power management system.

[0016] Furthermore, the cathode is made of carbonaceous material and has a cylindrical appearance.

[0017] Furthermore, the anode is made of an alloy material and has a mesh structure in appearance.

[0018] The beneficial effects of the present invention are:

[0019] (1) The present invention achieves higher purity of iron products recovered from red mud. By controlling the electrolytic potential, the present invention achieves selective reduction of iron minerals in red mud, resulting in product purity exceeding 99%. This is significantly improved compared to the product purity (45-60%) of traditional physical beneficiation methods (magnetic separation, gravity separation). Compared to high-temperature pyrometallurgy, since no coke reduction and slag-making processes are involved, harmful elements such as phosphorus, sulfur, and aluminum in the iron are also greatly reduced, and the product indicators can meet the standard requirements for pig iron.

[0020] (2) The present invention has lower energy consumption and is more environmentally friendly. The present invention uses electrolysis to recover iron minerals from red mud. Compared with conventional high-temperature smelting technology that recovers iron at temperatures above 1400°C, the reaction temperature only needs to be around 110-120°C, greatly reducing energy consumption. In addition, due to selective electrolysis, the entire treatment process only involves the reduction of iron minerals, and no other side reactions occur. The only gas discharged during the entire reaction process is oxygen, which is pollution-free to the environment.

[0021] Therefore, from the perspective of iron product quality and the economic efficiency of the technical route, the iron recovery method of the present invention has obvious advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the device structure of Example 2 of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to this embodiment.

[0024] Example 1

[0025] This embodiment provides a method for recovering iron from red mud, and the specific process is as follows:

[0026] The red mud slurry in the red mud pipeline of the alumina workshop is mineralized and sent to the electrolysis system for electrolysis. The caustic soda concentration in the electrolyte is controlled at 5-25 mol / L, the electrolysis voltage is between 1.3v-1.6v, and the temperature of the red mud slurry in the electrolysis system is maintained between 110-120°C. The electrolysis is stopped after 4 hours, and the iron on the cathode of the electrolysis system is stripped to obtain a high-purity iron product.

[0027] Example 2

[0028] This embodiment provides a device for implementing the method described in embodiment 1, such as Figure 1 As shown, it includes a red mud mineralization system 1, a metering feeding system 2, an electrolysis system 3, and an iron stripping system 4 connected in sequence; the device also includes a heating medium storage tank 7, an alkali solution storage tank 6 and a gas collection system 5, and the heating medium storage tank 7, the alkali solution storage tank 6 and the gas collection system 5 are connected to the electrolysis system 3, the heating medium storage tank 7 is used to store the heating medium and transport the heating medium to the electrolysis system 3, the alkali solution storage tank 6 is used to store the caustic alkali solution and transport the caustic alkali solution to the electrolysis system 3, and the gas collection system 5 is used to collect and process the tail gas discharged from the electrolysis system 3.

[0029] In the above-described apparatus, red mud slurry enters red mud mineralization system 1 for mineralization. After mineralization is complete, it is fed by metering feeding system 2 to electrolysis system 3 for electrolysis. After electrolysis, iron stripping system 4 strips the iron from the cathode, producing a high-purity iron product. A heating medium storage tank 7 provides heating medium (heating oil in this embodiment) to the electrolysis system. The heating medium maintains the red mud slurry at a temperature of 110-120°C.

[0030] In this embodiment, the electrolysis system 3 uses an anode, a cathode and a reference electrode to form a three-electrode system, and is powered by a DC power management system.

[0031] More specifically, in this embodiment, the cathode is made of a carbonaceous material and has a cylindrical appearance. The carbonaceous material is preferably graphite.

[0032] More specifically, in this embodiment, the anode is made of an alloy material and has a mesh structure in appearance. The alloy material is preferably a titanium / platinum alloy.

[0033] Those skilled in the art can make various corresponding changes and modifications based on the above technical solutions and concepts, and all of these changes and modifications should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for recovering iron from red mud, characterized in that: The red mud slurry in the red mud pipeline of the alumina workshop is mineralized and fed into the electrolysis system for electrolysis. The caustic soda concentration in the electrolyte is controlled to be 5-25 mol / L, the electrolysis voltage is between 1.3v-1.6v, and the temperature of the red mud slurry in the electrolysis system is maintained between 110-120°C. The electrolysis is stopped after 2-8 hours, and the iron on the cathode of the electrolysis system is stripped to obtain a high-purity iron product. The device for recovering iron from red mud includes a red mud mineralization system, a metering feeding system, an electrolysis system, and an iron stripping system connected in sequence; the device also includes a heating medium storage tank, an alkali solution storage tank and a gas collection system, and the heating medium storage tank, alkali solution storage tank and gas collection system are connected to the electrolysis system; the heating medium storage tank is used to store the heating medium and transport the heating medium to the electrolysis system, the alkali solution storage tank is used to store the caustic alkali solution and transport the caustic alkali solution to the electrolysis system, and the gas collection system is used to collect and process the exhaust gas discharged from the electrolysis system.

2. The method according to claim 1, characterized in that The electrolysis system adopts an anode, a cathode and a reference electrode to form a three-electrode system, and is powered by a DC power management system.

3. The method according to claim 2, characterized in that The cathode is made of carbonaceous material and has a cylindrical appearance.

4. The method according to claim 2, characterized in that The anode is made of alloy material and has a mesh structure in appearance.

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