Co-processing technology for high-iron red mud and various carbon-containing solid wastes

Abstract

The invention relates to a co-treatment process for high-iron red mud and various carbon-containing solid wastes. The co-treatment process comprises the working procedures of raw material preparation, ball pressing, drying and pre-reduction, iron reduction, titanium-silicon reduction, tailing treatment and the like. According to the method, the problems of low iron grade and high impurity aluminum content of a red mud iron recovery process are solved, the comprehensive utilization problem of other solid wastes and the utilization problem of tailings after extraction are synchronously realized, and the purpose of treating wastes with wastes is realized.

Description

Technical Field

[0001] The present application relates to the technical field of solid waste resource utilization, and in particular to a process for the coordinated disposal of high-iron red mud and various carbon-containing solid wastes. Background Art

[0002] By 2024, my country's total alumina production capacity will be approximately 99.52 million tons, with an operating capacity of approximately 76 million tons. The industry will have a cumulative stockpile of approximately 1.7 billion tons of red mud, covering an area of more than 100,000 mu (approximately 16,000 acres). This not only occupies land but also pollutes the air and soil, posing a certain safety and environmental risk. According to statistics, the national comprehensive utilization rate of red mud is only about 10%. Since red mud contains a large amount of valuable metals such as iron, aluminum, titanium, vanadium, and scandium, it has resulted in a large amount of resource waste. For the utilization of high-iron red mud, the traditional and mature utilization process is magnetic separation to extract iron. However, the iron concentrate obtained contains more impurities and a higher content of alumina, resulting in a lower grade and added value of the iron concentrate. In addition, the recovery rate of iron oxide is low throughout the extraction process.

[0003] Guinea's high-iron red mud has an Fe2O3 content exceeding 60% and a TiO2 content exceeding 5%, making it highly valuable for recycling. Patent CN112442565A discloses a process for reducing and extracting iron from high-iron red mud. The invention first dries and crushes the high-iron red mud to particles smaller than -1mm, then mixes it with a carbon-based compound to produce high-iron red mud pellets. The pellets are then reduced and roasted in a rotary kiln at 1050-1250°C for 90-180 minutes, resulting in a molten material for an electric arc furnace. The molten material is then added to an electric arc furnace at 1350-1550°C for 30-80 minutes. The iron oxides in the melt are reduced to metallic iron, and the resulting calcium aluminate slag is discharged from the electric arc furnace. This method only recycles the iron in the red mud, resulting in waste of other valuable elements and tailings. Summary of the Invention

[0004] In order to solve the problems of low iron grade and high impurity aluminum content in the red mud iron recovery process, and simultaneously realize the comprehensive utilization of other solid wastes and the utilization of tailings after extraction, and achieve the purpose of treating waste with waste, the present application provides a high-iron red mud and a variety of carbon-containing solid waste coordinated disposal process.

[0005] This application provides a process for the coordinated disposal of high-iron red mud and various carbon-containing solid wastes, which adopts the following technical solutions:

[0006] A process for the coordinated disposal of high-iron red mud and multiple carbon-containing solid wastes comprises the following steps:

[0007] S1. Raw material preparation: crushing high-iron red mud to a particle size of 0.1-1 mm to obtain high-iron red mud powder; mixing solid waste fly ash and electrolytic aluminum waste cathode and crushing them to a particle size of 0.1-1 mm to obtain carbon-based reducing agent powder;

[0008] S2. Ball pressing: mixing high iron red mud powder and carbon-based reducing agent powder in a weight ratio of 1: (0.1-0.5), then adding flux and binder, wherein the weight ratio of high iron red mud powder, flux and binder is 1: (0.13-0.14): (0.01-0.03), and pressing into red mud pellets after mixing;

[0009] S3, drying and pre-reduction: sending the red mud pellets into a rotary kiln for reduction roasting at a temperature of 800-1000°C for 20-60 minutes to obtain pre-reduced red mud pellets;

[0010] S4. Iron reduction: The pre-reduced red mud pellets are placed in a heating furnace for melting reduction at a melting temperature of 1400-1600° C. for 60-90 minutes. The iron oxide and iron oxides in the red mud pellets melt at this temperature and undergo a reduction reaction, ultimately reducing to molten elemental iron. The molten elemental iron is discharged from the bottom of the furnace, leaving unmelted slag in the heating furnace to achieve slag-liquid separation. The recovery rate of elemental iron is controlled to be 70-90%.

[0011] S5. Titanium and silicon reduction: Continue to adjust the temperature of the heating furnace to 1500-1700°C for 30-90 minutes to melt the remaining slag, add a carbon, aluminum, and magnesium reducing agent into the heating furnace, and add the carbon, aluminum, and magnesium reducing agent to the remaining slag in a weight ratio of (0.1-0.2):1 to reduce the titanium and silicon elements in the melt, discharge it from the bottom of the furnace, and obtain titanium-silicon ferroalloy after cooling;

[0012] S6. Tailings treatment: The tailings remaining in the furnace are separated, tempered, and ground to produce aluminum oxide enriched powder with an aluminum oxide content of 35%-45% or cementitious materials.

[0013] By adopting the above-mentioned technical scheme, this application utilizes high-iron red mud as raw material and solid wastes such as fly ash and electrolytic aluminum waste cathode as carbon-based reducing agents, thereby achieving the purpose of treating waste with waste. In view of the complex composition of high-iron red mud, the segmented utilization achieves an iron recovery rate of more than 96% and a titanium recovery rate of more than 70% in the red mud. The purity of the obtained elemental iron is higher than 95%. The final tailings are processed into alumina enriched powder or cementitious materials for cement production, thereby realizing the deep utilization of red mud.

[0014] Since high-iron red mud itself contains moisture, it needs to be dried and pre-reduced after being pressed into balls to remove the moisture in the red mud balls. In the pre-reduction process, part of the iron oxide in the red mud pellets is reduced to ferroferric oxide, making the pellets more compact and reducing the breakage and powder loss of the red mud pellets. This ensures that the red mud pellets will not be lost due to the volatilization of powder with high-temperature flue gas, resulting in material loss, and ensures the recovery rate.

[0015] Optionally, the binder is diatomaceous earth.

[0016] The above-mentioned technical solution utilizes diatomaceous earth, a lightweight, porous structure with excellent adsorption properties. Therefore, after being formed into red mud pellets, its adsorption properties enable a tight bond between the high-iron red mud powder and the carbon-based reducing agent powder, thereby promoting a more complete reduction reaction and increasing iron recovery. During the subsequent iron reduction process, the diatomaceous earth binds the slag, allowing it to float above the molten iron, facilitating separation. As the volume of the molten material in the heating furnace decreases, the presence of the diatomaceous earth facilitates the separation of the slag and liquid.

[0017] Optionally, the binder is diatomaceous earth-loaded potassium silicate, the surface of the diatomaceous earth-loaded potassium silicate is further coated with microcrystalline wax, and the diatomaceous earth-loaded potassium silicate coated with microcrystalline wax is prepared by the following steps:

[0018] Diatomaceous earth and potassium silicate are added to an anhydrous ethanol solution in a weight ratio of 1: (0.3-0.5), and the temperature is raised to 60-90°C after ultrasonic treatment. Then, microcrystalline wax is added, wherein the weight ratio of diatomaceous earth to microcrystalline wax is 1: (1.5-2). After ultrasonic dispersion, the solution is filtered and dried to obtain diatomaceous earth-loaded potassium silicate coated with microcrystalline wax.

[0019] By adopting the above technical solution, diatomaceous earth is used as a carrier, and sodium silicate and diatomaceous earth are added to synergistically play a bonding role on the red mud pellets. As the temperature increases, potassium silicate melts and can also play a bonding role at high temperatures, reducing the damage to the internal structure of diatomaceous earth caused by the high temperature environment, which leads to a decrease in the bonding effect. The adsorption bonding of diatomaceous earth and the melting bonding of potassium silicate enable the high-iron red mud and carbon-based reducing agent in the red mud pellets to be more tightly combined, promote the full progress of the reduction reaction, and reduce the loss of powder due to volatilization of high-temperature steam.

[0020] Microcrystalline wax wraps the diatomaceous earth loaded potassium silicate to improve the hydrophobicity of the surface. On the one hand, it promotes the discharge of moisture in the red mud pellets in the pre-reduction process. On the other hand, it helps to further improve the dispersibility of the diatomaceous earth loaded potassium silicate in the red mud powder and the carbon-based reducing agent powder, reduce agglomeration, and enable the binder to more evenly bond the red mud powder and the carbon-based reducing agent powder. In a high-temperature environment, the microcrystalline wax first melts and then carbonizes and evaporates, and evaporates along with the moisture in the red mud pellets, leaving a number of micropores in the pellets. The potassium silicate fills these micropores after melting, further playing the role of bonding the pellets in a high-temperature environment.

[0021] Optionally, in S3, drying and pre-reduction, the calcination temperature is 880-980°C, and the calcination time is 30-40 min. The calcination temperature can be 880°C, 900°C, 920°C, 950°C, or 980°C, and the calcination time can be 30 min, 32 min, 35 min, 38 min, or 40 min.

[0022] By adopting the above technical solution, in the drying and pre-reduction process, within the range of a calcination temperature of 880-980°C and a calcination time of 30-40 minutes, on the one hand, after the diatomaceous earth is first calcined within this temperature range, its internal structure becomes more stable and its adsorption performance is further improved, thereby facilitating better floating on the upper layer of molten elemental iron in the subsequent iron reduction process, thereby facilitating slag-liquid separation; on the other hand, the potassium silicate in the binder can melt to bond the red mud and the carbon-based reducing agent, thereby promoting the full progress of the reduction reaction and reducing the material loss caused by the red mud pellets being broken into powder and volatilized at high temperature.

[0023] Optionally, in the S2 pelletizing process, the diameter of the red mud pellets is 4 cm to 6 cm. The diameter of the red mud pellets can be 4 cm, 4.5 cm, 5 cm, 5.5 cm or 6 cm.

[0024] By adopting the above technical solution, when the diameter of the red mud pellets is within 4-6 cm, it can be ensured that the moisture in the red mud pellets can be fully discharged during the pre-reduction process, and the high temperature environment increases the strength of the pellets. As a result, in the subsequent iron reduction and titanium and silicon reduction, it is less likely that the powder in the pellets will be carried out due to volatilization of high-temperature flue gas, thereby ensuring the yield while promoting the full progress of the reduction reaction.

[0025] Optionally, in the S2 ball pressing, the pressing pressure is 5-10 MPa.

[0026] Optionally, based on the total weight of the high-iron red mud, the components of the high-iron red mud include 55 wt%-70wt% of iron oxide, 8 wt%-15 wt% of aluminum oxide, 5 wt%-8 wt% of titanium dioxide and 3 wt%-8 wt% of silicon dioxide, and the water content of the high-iron red mud is less than 15 wt%.

[0027] Optionally, the flux is one or more of calcium oxide, fluorite or limestone.

[0028] By adopting the above technical solution, adding a flux helps to lower the melting temperature of iron oxide in red mud and promote the reduction reaction.

[0029] In summary, this application has the following beneficial effects:

[0030] 1. This application utilizes high-iron red mud as raw material and solid wastes such as fly ash and electrolytic aluminum waste cathode as carbon-based reducing agents, achieving the purpose of treating waste with waste. In view of the complex composition of high-iron red mud, segmented utilization achieves an iron recovery rate of more than 96% and a titanium recovery rate of more than 70% in the red mud. The purity of the obtained elemental iron is higher than 95%. The final tailings are processed into alumina enriched powder or cementitious materials for cement production, realizing the deep utilization of red mud.

[0031] Since high-iron red mud itself contains moisture, it needs to be dried and pre-reduced after being pressed into balls to remove the moisture in the red mud balls. In the pre-reduction process, part of the iron oxide in the red mud pellets is reduced to ferroferric oxide, making the pellets more compact and reducing the breakage and powder loss of the red mud pellets. This ensures that the red mud pellets will not be lost due to the volatilization of powder with high-temperature flue gas, resulting in material loss, and ensures the recovery rate.

[0032] 2. Diatomaceous earth has a lightweight, porous structure and excellent adsorption properties. Therefore, after being made into red mud pellets, its adsorption properties can be used to tightly bind the high-iron red mud powder and carbon-based reducing agent powder, thereby making the reduction reaction more complete and improving the iron recovery rate. In the subsequent iron reduction process, the diatomaceous earth can bind the slag and float it on the upper layer of the molten iron, facilitating the separation of the two.

[0033] 3. In the drying and pre-reduction process, under the conditions of a roasting temperature of 880-980°C and a roasting time of 30-40 minutes, on the one hand, after the diatomaceous earth is first calcined within this temperature range, its internal structure will become more stable and its adsorption performance will be further improved, thereby helping to better float on the upper layer of molten elemental iron in the subsequent iron reduction process, facilitating slag-liquid separation; on the other hand, the potassium silicate in the binder can melt to bond the red mud and the carbon-based reducing agent, promote the full progress of the reduction reaction, and reduce the situation where the red mud pellets are broken into powder and volatilized with the high-temperature flue gas, resulting in material loss. DETAILED DESCRIPTION

[0034] Experimental procedures in the following examples of the present invention, where specific conditions are not specified, generally followed conventional conditions or those recommended by the manufacturer. The various commonly used chemical reagents used in the examples are all commercially available products. The sources of the following raw materials are disclosed solely for the purpose of sufficient disclosure and are not intended to limit the scope of protection.

[0035] The fixed carbon content of solid waste fly ash is 62-65%, and the fixed carbon content of electrolytic aluminum waste cathode is 65-70%;

[0036] Diatomaceous earth CAS number 61790-53-2, particle size grade 1-5mm;

[0037] Potassium silicate CAS number: 1312-76-1, particle size grade: 1-3mm;

[0038] Microcrystalline wax CAS number: 8001-75-0, particle size grade 1-3mm;

[0039] Paraffin wax CAS number: 8002-74-2, particle size grade 1-3mm;

[0040] Calcium oxide CAS number: 73018-51-6, particle size grade 1-3mm;

[0041] The carbon-aluminum-magnesium reducing agent accounts for 40% carbon, 40% aluminum and 20% magnesium.

[0042] Example

[0043] Examples 1.1-1.3

[0044] A process for the coordinated disposal of high-iron red mud and multiple carbon-containing solid wastes comprises the following steps:

[0045] S1. Raw material preparation: crushing high-iron red mud to a particle size of 0.1-1 mm to obtain high-iron red mud powder; mixing solid waste fly ash and electrolytic aluminum waste cathode and crushing them to a particle size of 0.1-1 mm to obtain carbon-based reducing agent powder; wherein the high-iron red mud comprises 55 wt%-70 wt% of iron oxide, 8 wt%-15 wt% of aluminum oxide, 5 wt%-8 wt% of titanium dioxide and 3 wt%-8 wt% of silicon dioxide, and the water content of the high-iron red mud is less than 15 wt%.

[0046] S2. Ball pressing: Mix high-iron red mud powder and carbon-based reducing agent powder in a weight ratio of 1: (0.1-0.5), then add flux and binder. The weight ratio of high-iron red mud powder, flux and binder is 1: (0.13-0.14): (0.01-0.03). After mixing, put it into a ball press. Set the pressing pressure to 6 MPa and press it into red mud pellets at room temperature. The diameter of the red mud pellets is 5 cm. Among them, the flux is calcium oxide and the binder is diatomaceous earth.

[0047] S3, drying and pre-reduction: sending the red mud pellets into a rotary kiln for reduction roasting at a temperature of 800-1000°C for 20-60 minutes to obtain pre-reduced red mud pellets;

[0048] S4. Iron reduction: The pre-reduced red mud pellets are placed in a heating furnace for melting reduction. The heating furnace is an electric furnace with a melting temperature of 1400-1600°C and a melting time of 60-90 minutes. The iron oxide and iron oxides in the red mud pellets melt at this temperature and undergo a reduction reaction, ultimately reducing to molten elemental iron. The molten elemental iron is discharged from the discharge port at the bottom of the furnace, while the unmelted slag remains in the heating furnace to achieve slag-liquid separation. The recovery rate of elemental iron is controlled to be 80%;

[0049] S5. Titanium and silicon reduction: Continue to adjust the temperature of the heating furnace to 1500-1700°C for 30-90 minutes to melt the remaining slag. Add carbon, aluminum, and magnesium reducing agents into the heating furnace. The weight ratio of the carbon, aluminum, and magnesium reducing agents to the remaining slag is (0.1-0.2):1. After the titanium and silicon elements are reduced, the tailings float on the upper layer of the melt. The melt is discharged from the bottom of the furnace and cooled to obtain titanium-silicon ferroalloy. The composition of the titanium-silicon ferroalloy is 35% titanium, 50% silicon, and 15% iron.

[0050] S6. Tailings treatment: The tailings remaining in the heating furnace are separated, tempered, and ground to produce aluminum oxide enriched powder with an aluminum oxide content of 45% or cementitious materials.

[0051] The process parameters of each step of the coordinated treatment process of high-iron red mud and various carbon-containing solid wastes in Examples 1.1-1.3 are shown in Table 1.

[0052] Table 1 Process parameters of Examples 1.1-1.3

[0053]

[0054] Examples 2.1-2.3

[0055] A process for the coordinated disposal of high-iron red mud and multiple carbon-containing solid wastes is described, which differs from Example 1.2 in that diatomaceous earth is replaced with an equal amount of diatomaceous earth coated with microcrystalline wax and loaded with potassium silicate.

[0056] The preparation steps of diatomaceous earth-loaded potassium silicate coated with microcrystalline wax are as follows: diatomaceous earth and potassium silicate are added into an anhydrous ethanol solution in a weight ratio of 1:(0.3-0.5), the temperature is raised to 80°C after ultrasonic treatment, and then microcrystalline wax is added in a weight ratio of diatomaceous earth to microcrystalline wax of 1:(1.5-2). After ultrasonic dispersion for 20 minutes, the solution is filtered and dried at 20°C to obtain diatomaceous earth-loaded potassium silicate coated with microcrystalline wax.

[0057] In Example 2.1, the weight ratio of diatomaceous earth to potassium silicate is 1:0.3; the weight ratio of diatomaceous earth to microcrystalline wax is 1:1.5;

[0058] In Example 2.2, the weight ratio of diatomaceous earth to potassium silicate is 1:0.4; the weight ratio of diatomaceous earth to microcrystalline wax is 1:1.7;

[0059] In Example 2.3, the weight ratio of diatomaceous earth to potassium silicate is 1:0.5; the weight ratio of diatomaceous earth to microcrystalline wax is 1:2.

[0060] Example 3

[0061] A process for the coordinated disposal of high-iron red mud and multiple carbon-containing solid wastes, which differs from Example 2.2 in that an equal amount of paraffin wax is used to replace microcrystalline wax.

[0062] Example 4

[0063] A process for the coordinated disposal of high-iron red mud and multiple carbon-containing solid wastes, which differs from Example 2.2 in that an equal amount of calcium silicate is used to replace potassium silicate.

[0064] Example 5

[0065] A process for the coordinated disposal of high-iron red mud and multiple carbon-containing solid wastes, which differs from Example 2.2 in that the amount of microcrystalline wax used is 0 kg.

[0066] Examples 6.1-6.4

[0067] A process for the coordinated disposal of high-iron red mud and various carbon-containing solid wastes, which differs from Example 1.2 in that, in S3, drying and pre-reduction, the roasting temperature and roasting time are different;

[0068] The calcination temperature in Example 6.1 is 980° C. and the calcination time is 30 min.

[0069] The calcination temperature in Example 6.2 is 880°C and the calcination time is 40 min.

[0070] The calcination temperature in Example 6.3 is 1100°C and the calcination time is 30 min.

[0071] The calcination temperature in Example 6.4 is 650°C and the calcination time is 30 min.

[0072] Comparative Example 1

[0073] A process for the coordinated disposal of high-iron red mud and multiple carbon-containing solid wastes, which differs from Example 1.2 in that the amount of binder used is 0 kg.

[0074] Comparative Example 2

[0075] A process for the coordinated disposal of high-iron red mud and multiple carbon-containing solid wastes is described, which differs from Example 1.2 in that diatomaceous earth is replaced by an equal amount of bentonite.

[0076] Comparative Example 3

[0077] A process for the coordinated disposal of high-iron red mud and multiple carbon-containing solid wastes, which differs from Example 1.2 in that the amount of flux used is 0 kg.

[0078] Performance testing experiment

[0079] 1. Component Analysis

[0080] For the coordinated treatment process of high-iron red mud and various carbon-containing solid wastes in Example 1.2, the elemental iron and iron slag produced in the iron reduction process, the titanium-silicon-iron alloy produced in the titanium and silicon reduction process, and the final slag obtained were sampled and analyzed for composition using fluorescence analysis. The test results are shown in Table 2.

[0081] 2. Compressive strength test of red mud pellets

[0082] The red mud pellets prepared in Examples 1.1-1.3, Examples 2.1-2.3, Examples 3-5, Examples 6.1-6.2 and Comparative Examples 1-3 were sampled after S2 pelletizing and after S3 drying and pre-reduction, and the compressive strength of the red mud pellets was tested respectively, and the strength improvement rate was calculated. The greater the strength improvement rate, the more fully dried the red mud pellets were and the better the tightness.

[0083] Strength improvement rate = (S3 pre-reduction ball strength - S2 ball initial ball strength) ÷ S2 ball initial ball strength

[0084] 3. Recovery rate and purity test

[0085] The elemental iron recovered according to Example 1.2, Example 2.2 and Comparative Examples 1-3 was tested for recovery rate and purity, and the recovery rate of titanium was tested.

[0086] Recovery rate of elemental iron = mass of iron in the obtained metal product / iron content in high-iron red mud

[0087] Titanium recovery rate in titanium-silicon ferrosilicon alloy = mass of titanium in the obtained metal product / titanium content in high-iron red mud

[0088] The compressive strength test results of Examples 1.1-1.2, Examples 2.1-2.3, Examples 3-5, Examples 6.1-6.2 and Comparative Examples 1-3 are shown in Table 3, and the recovery and purity test results of Example 1.2, Example 2.2 and Comparative Examples 1-3 are shown in Table 4.

[0089] Table 2 Composition analysis of elemental iron, titanium-ferrosilicon alloy and final slag obtained in Example 1.2

[0090]

[0091] Table 3 Strength test results

[0092]

[0093] Table 4 Recovery rate and purity test results

[0094]

[0095] Combining Examples 1.1-1.3 and Comparative Examples 1-3 with Tables 2-4, it can be seen that Examples 1.1-1.3 are all better than Comparative Examples 1-3, indicating that since the high-iron red mud itself contains moisture, the high-iron red mud needs to be dried and pre-reduced after being pelletized to remove the moisture in the red mud pellets. In addition, the temperature conditions of the pre-reduction process reduce part of the iron oxide in the red mud pellets to ferroferric oxide, making the pellets more compact and reducing the breakage and powdering of the red mud pellets. This ensures that the red mud pellets will not be lost due to the volatilization of powder into high-temperature flue gas, resulting in material loss, thereby ensuring the recovery rate.

[0096] In conjunction with Example 1.2 and Comparative Example 2 and in conjunction with Table 3, it can be seen that the present application selects diatomite as a binder, and utilizes its lightweight porous structure and good adsorption properties, therefore after making red mud pellets, its adsorptivity can make high iron red mud powder and carbon-based reducing agent powder closely combined, and then make reduction reaction more sufficient, improve the recovery rate of iron. In the subsequent iron reduction process, diatomite can bond slag material to float on the upper layer of molten iron element, facilitate the separation of the two, and then improve extraction purity. Although bentonite has good cohesiveness as a binder, due to the high temperature environment bentonite will expand, causing the powder in the red mud pellets to expose powder, the powdered material will volatilize with the high temperature flue gas and cause the recovery rate to decrease, and the reduction reaction is insufficient, causing solid waste to be not fully utilized.

[0097] Combining Examples 1.1-1.3 and Comparative Examples 1-3 and Table 4, it can be seen that Examples 1.1-1.3 are all better than Comparative Examples 1-3, indicating that the present application utilizes high-iron red mud as raw material and solid wastes such as fly ash and electrolytic aluminum waste cathodes as carbon-based reducing agents, thereby achieving the purpose of treating waste with waste. In view of the complex composition of high-iron red mud, the segmented utilization achieves an iron recovery rate of more than 96% and a titanium recovery rate of more than 70% in the red mud. The purity of the obtained elemental iron is higher than 95%. The final tailings are processed into alumina enriched powder or cementitious materials for producing cement, thereby achieving deep utilization of red mud.

[0098] Combining Examples 2.1-2.3 with Example 1.2 and Table 2-4, it can be seen that the pellets of Examples 2.1-2.3 have better tightness after calcination than the pellets of Example 1.2, indicating that the diatomaceous earth loaded with potassium silicate coated with microcrystalline wax helps to improve the dryness and bonding tightness of the red mud pellets, thereby helping to reduce the subsequent breakage and powdering of the red mud pellets during high-temperature melting, resulting in the loss of powder due to high-temperature volatilization and a decrease in recovery rate.

[0099] Combining Example 2.2 with Examples 3-5 and Table 3, it can be seen that Example 2.2 is superior to Examples 3-5, indicating that the use of diatomaceous earth and sodium silicate has a synergistic bonding effect on the red mud pellets. As the temperature increases, potassium silicate melts and can also play a bonding role at high temperatures. The adsorption bonding of diatomaceous earth and the melting bonding of potassium silicate enable the high-iron red mud in the red mud pellets to be more tightly bonded to the carbon-based reducing agent, promoting the full progress of the reduction reaction and reducing the loss of powder due to volatilization of high-temperature steam.

[0100] Microcrystalline wax wraps the diatomaceous earth loaded potassium silicate to improve the hydrophobicity of the surface. On the one hand, it promotes the discharge of moisture in the red mud pellets in the pre-reduction process. On the other hand, it helps to further improve the dispersibility of the diatomaceous earth loaded potassium silicate in the red mud powder and the carbon-based reducing agent powder, reduce agglomeration, and enable the binder to more evenly bond the red mud powder and the carbon-based reducing agent powder. In a high-temperature environment, the microcrystalline wax first melts and then carbonizes and evaporates, and evaporates along with the moisture in the red mud pellets, leaving a number of micropores in the pellets. The potassium silicate fills these micropores after melting, further playing the role of bonding the pellets in a heated environment until the metal components in the red mud pellets fully complete the reduction reaction.

[0101] Combining Examples 6.1-6.4 of the present application and Table 3, it can be seen that Examples 6.1-6.2 are better than Examples 6.3-6.4. The reason may be that in the drying and pre-reduction process, the calcination temperature is 880-980°C and the calcination time is 30-40 min. On the one hand, after the diatomaceous earth is first calcined within this temperature range, its internal structure becomes more stable and the adsorption performance is further improved, which helps in the subsequent iron reduction process. It can better float on the upper layer of the molten elemental iron, facilitate slag-liquid separation, and improve purity; on the other hand, the potassium silicate in the binder can melt to bond the red mud and the carbon-based reducing agent, promote the full progress of the reduction reaction, and reduce the red mud pellets. The situation of material loss caused by high-temperature volatilization is reduced due to the crushing of powder. When the temperature is too low (i.e., Example 6.3), the roasting process will result in poor calcination effect on diatomaceous earth, which is not conducive to adsorption at high temperatures, and the bonding effect of potassium silicate at this temperature is poor. When the roasting temperature is too high (i.e., Example 6.4), the powder in the high-iron red mud and potassium silicate will melt and flow out of the red mud pellets, making it difficult to tighten the red mud pellets, and easily causing the pellets to break and lose powder, reducing the recovery rate.

[0102] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A process for the coordinated disposal of high-iron red mud and various carbon-containing solid wastes, characterized by: The following steps are involved: S1. Raw material preparation: crushing high-iron red mud to a particle size of 0.1-1 mm to obtain high-iron red mud powder; mixing solid waste fly ash and electrolytic aluminum waste cathode and crushing them to a particle size of 0.1-1 mm to obtain carbon-based reducing agent powder; S2. Ball pressing: mixing high iron red mud powder and carbon-based reducing agent powder in a weight ratio of 1: (0.1-0.5), then adding flux and binder, wherein the weight ratio of high iron red mud powder, flux and binder is 1: (0.13-0.14): (0.01-0.03), and pressing into red mud pellets after mixing; S3, drying and pre-reduction: sending the red mud pellets into a rotary kiln for reduction roasting at a temperature of 800-1000°C for 20-60 minutes to obtain pre-reduced red mud pellets; S4. Iron reduction: The pre-reduced red mud pellets are placed in a heating furnace for melting reduction at a melting temperature of 1400-1600° C. for 60-90 minutes. The iron oxide and iron oxides in the red mud pellets melt at this temperature and undergo a reduction reaction, ultimately reducing to molten elemental iron. The molten elemental iron is discharged from the bottom of the furnace, leaving unmelted slag in the heating furnace to achieve slag-liquid separation. The recovery rate of elemental iron is controlled to be 70-90%. S5. Titanium and silicon reduction: Continue to adjust the temperature of the heating furnace to 1500-1700°C for 30-90 minutes to melt the remaining slag, add a carbon, aluminum, and magnesium reducing agent into the heating furnace, and add the carbon, aluminum, and magnesium reducing agent to the remaining slag in a weight ratio of (0.1-0.2):1 to reduce the titanium and silicon elements in the melt, discharge it from the bottom of the furnace, and obtain titanium-silicon ferroalloy after cooling; S6. Tailings treatment: The tailings remaining in the furnace are separated, tempered, and ground to produce aluminum oxide enriched powder with an aluminum oxide content of 35%-45% or cementitious materials.

2. The process for co-processing high-iron red mud and multiple carbon-containing solid wastes according to claim 1, characterized in that: The binder is diatomaceous earth.

3. The process for co-processing high-iron red mud and various carbon-containing solid wastes according to claim 1, characterized in that: The binder is diatomaceous earth loaded potassium silicate, the surface of the diatomaceous earth loaded potassium silicate is further coated with microcrystalline wax, and the diatomaceous earth loaded potassium silicate coated with microcrystalline wax is prepared by the following steps: Diatomaceous earth and potassium silicate are added to an anhydrous ethanol solution in a weight ratio of 1: (0.3-0.5), and the temperature is raised to 60-90°C after ultrasonic treatment. Then, microcrystalline wax is added, wherein the weight ratio of diatomaceous earth to microcrystalline wax is 1: (1.5-2). After ultrasonic dispersion, the solution is filtered and dried to obtain diatomaceous earth-loaded potassium silicate coated with microcrystalline wax.

4. The process for co-processing high-iron red mud and multiple carbon-containing solid wastes according to claim 1, characterized in that: In the drying and pre-reduction step S3, the calcination temperature is 880-980° C., and the calcination time is 30-40 minutes.

5. The process for co-processing high-iron red mud and multiple carbon-containing solid wastes according to claim 1, characterized in that: In the S2 pelletizing process, the diameter of the red mud pellets is 4 cm to 6 cm.

6. The process for co-processing high-iron red mud and various carbon-containing solid wastes according to claim 1, characterized in that: In the S2 pelletizing process, the pressing pressure is 5-10 MPa.

7. The process for co-processing high-iron red mud and multiple carbon-containing solid wastes according to claim 1, characterized in that: Based on the total weight of the high-iron red mud, the components of the high-iron red mud include 55 wt%-70 wt% of iron oxide, 8 wt%-15 wt% of aluminum oxide, 5 wt%-8 wt% of titanium dioxide and 3 wt%-8 wt% of silicon dioxide, and the water content of the high-iron red mud is less than 15 wt%.

8. The process for co-processing high-iron red mud and multiple carbon-containing solid wastes according to claim 1, characterized in that: The flux is one or more of calcium oxide, fluorite or limestone.

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