Method for co-disposal and utilization of red mud and steel dust

Abstract

The application provides a method for cooperatively disposing and utilizing red mud and steel dust, and relates to the technical field of red mud. The method for cooperatively disposing and utilizing red mud and steel dust specifically comprises the following steps: S1. drying and fine grinding; S2. batching and pelletizing; S3. roasting, grinding and selecting; and S4. hydrothermal reaction and separating. The method for cooperatively disposing and utilizing red mud and steel dust can sequentially emit zinc, magnetically select iron powder, and separate tobermorite products and sodium aluminate solution through hydrothermal reaction, thereby providing a new scheme for the efficient separation and recovery of valuable elements such as iron, zinc, aluminum, silicon and sodium in red mud and steel dust, and realizing the cooperative disposal and value-added utilization of the two.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgical solid waste treatment, in particular to a method for co-treating and utilizing red mud and steel dust. BACKGROUND

[0002] Red mud is an industrial solid waste discharged in the extraction of alumina in the aluminum industry. It is called red mud because it contains iron oxide and looks like red soil. Due to the difference in ore grade, production method and technical level, about 1.0-1.8 tons of red mud are discharged for every ton of alumina produced. The mineral composition of red mud is complex. The existing technology generally only considers recovering iron from red mud or recovering iron at a low recovery rate while recovering aluminum. There is no effective method for comprehensive recovery and utilization of valuable components such as iron, aluminum, sodium and silicon in red mud. SUMMARY

[0003] (I) Technical problems solved

[0004] In view of the deficiencies of the prior art, the present application provides a method for co-treating and utilizing red mud and steel dust, which solves the problem of complex and low efficiency of recovering valuable components from existing red mud, and also reasonably utilizes and recovers valuable components in steel dust.

[0005] (II) Technical solutions

[0006] To achieve the above object, the present application is realized by the following technical solutions: a method for co-treating and utilizing red mud and steel dust, specifically comprising the following steps:

[0007] S1. Drying and fine grinding

[0008] Drying and fine grinding the red mud to obtain fine-grained powder material;

[0009] S2. Proportioning and pelletizing

[0010] Proportioning and uniformly mixing the above fine-ground red mud with steel dust, reducing agent and additive according to the mass ratio to form lumps or pellets;

[0011] S3. Roasting and grinding

[0012] The above lumps or pellets are reduced and roasted at 800-1400℃ for 1-4h, and the volatile matter is collected to obtain zinc-rich dust. The roasted material is then ground and separated by magnetic separation to obtain iron powder product and slag containing aluminum, silicon, sodium and calcium;

[0013] S4. Hydrothermal reaction separation

[0014] The aluminum-silicon-sodium-calcium slag phase obtained by magnetic separation is subjected to hydrothermal reaction in a NaOH-Ca(OH)2 composite system at a reaction temperature of 100-400℃ for 1-4h, and tobermorite and sodium aluminate solution are separated by filtration.

[0015] Preferably, the red mud or tailings obtained after the selective iron removal of the red mud in step S1.

[0016] Preferably, the steel dust in step S2 is preferably a mixture of one or more of blast furnace gravity dust, blast furnace bag dust and blast furnace gas mud.

[0017] Preferably, the reducing agent in step S2 is a mixture of one or more of coke, anthracite, bituminous coal, lignite, semi coke and biochar.

[0018] Preferably, the additive in step S2 is a mixture of one or more of sodium carbonate, sodium sulfate, borax, sodium chloride and sodium hydroxide.

[0019] Preferably, the iron grade of the iron powder product in step S3 is above 90wt.%.

[0020] Preferably, the hydrothermal reaction system in step S2 has a CaO / SiO2 molar ratio of 0.5-2.0, a NaOH concentration of 5-50g / L and a liquid-solid ratio of 10-50mL / g.

[0021] (III) Beneficial effects

[0022] The present application provides a method for the collaborative disposal and utilization of red mud and steel dust.

[0023] The present application provides a method for the collaborative disposal and utilization of red mud and steel dust. Based on the complementarity of the components of red mud and steel dust and the similarity of the utilization routes, the present application proposes the idea of collaboratively disposing red mud and steel dust. Carbon in steel dust can be fully utilized as a reducing agent. Through direct reduction roasting, multiple functions such as the metallization of iron in red mud + dust, the activation of aluminum-silicon minerals (which can improve the dissolution performance of aluminum-silicon minerals in subsequent hydrothermal processes), and the reduction and volatilization of zinc in dust can be achieved simultaneously. This provides a material basis for the separation and productized recovery of valuable components. Through grinding-magnetic separation, productized recovery of iron can be achieved and separated from aluminum, silicon, sodium, calcium and other components. By using hydrothermal reaction dissolution-crystallization of silicon and calcium components to prepare tobermorite and separate it from aluminum and sodium components (sodium aluminate solution), productization of silicon and calcium can be achieved and recovered together with aluminum and sodium components. This provides a new technology for the efficient recovery and utilization of valuable components such as iron, aluminum, silicon, sodium, zinc and carbon in red mud and steel dust. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The present application is a flowchart. DETAILED DESCRIPTION

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1:

[0027] like Figure 1 As shown in the figure, this invention provides a method for the co-processing and utilization of red mud and steel dust, specifically including the following steps:

[0028] S1. Drying and fine grinding

[0029] Red mud is dried and finely ground to obtain fine-grained powder, of which the content of particles <0.1mm accounts for more than 70% by mass;

[0030] S2. Ingredient preparation and dough making

[0031] The finely ground red mud is mixed with steel dust, reducing agent, and additives in a mass ratio of red mud: steel dust: reducing agent: additives = 100:100:30:30. After mixing, the mixture is formed into lumps or pellets.

[0032] S3. Roasting and Grinding

[0033] The above-mentioned lumps or pellets are reduced and roasted at 1400℃ for 1 hour. The volatiles are collected to obtain zinc-rich flue dust. The roasted material is then separated into iron powder products and aluminum-silicon-sodium-calcium slag by grinding and magnetic separation.

[0034] S4 hydrothermal reaction separation

[0035] The aluminosilicate sodium calcium slag phase obtained by magnetic separation was subjected to hydrothermal reaction in a NaOH-Ca(OH)2 composite system at a reaction temperature of 400℃ for 4 hours. The tobermorite and sodium aluminate solution were then separated by filtration.

[0036] The red mud or tailings obtained after iron beneficiation of red mud in step S1 has an iron grade of 10wt.% to 60wt.%, an Al2O3 content of 5wt.% to 40wt.%, an SiO2 content of 3wt.% to 20wt.%, a CaO content of 0wt.% to 20wt.%, and a Na2O content of 0wt.% to 20wt.%.

[0037] The steel dust in step S2 is preferably a mixture of one or more of blast furnace gravity dust, blast furnace bag dust and blast furnace gas mud, with an iron grade of 15wt.% to 60wt.%, a carbon content of 5wt.% to 30wt.%, an Al2O3 content of 0 to 10wt.%, a SiO2 content of 0 to 15wt.%, a CaO content of 0 to 5wt.%, a Na2O content of 0 to 5wt.%, and a zinc content of 0 to 15wt.%.

[0038] The reducing agent in step S2 is a mixture of one or more of coke, anthracite, bituminous coal, lignite, semi-coke and biochar, and the additive in step S2 is a mixture of one or more of sodium carbonate, sodium sulfate, borax, sodium chloride and sodium hydroxide, the iron grade of the iron powder product in step S3 is above 90wt.%, and the hydrothermal reaction system in step S2 has a CaO / SiO2 molar ratio of 0.5 to 2.0, a NaOH concentration of 5 to 50g / L, and a liquid-solid ratio of 10 to 50mL / g.

[0039] Example 2:

[0040] As shown in Figure 1 , the embodiment of the present application provides a method for the synergistic disposal and utilization of red mud and steel dust, which specifically comprises the following steps:

[0041] S1. Drying and fine grinding

[0042] The red mud is dried and finely ground to obtain a fine-grained powder material, wherein the <0.1mm particle size content accounts for more than 70% by mass;

[0043] S2. Proportioning and pelletizing

[0044] The above finely ground red mud, steel dust, reducing agent and additive are proportioned and uniformly mixed according to the mass ratio of red mud: steel dust: reducing agent: additive = 100:30:0:0 to form pellets or briquettes;

[0045] S3. Roasting and grinding

[0046] The above pellets or briquettes are reduced and roasted at 800℃ for 1h, and the volatiles are collected to obtain zinc-rich flue dust, and the roasted material is then ground and separated by magnetic separation to obtain an iron powder product and an aluminum-silicon-sodium-calcium-containing residue;

[0047] S4. Hydrothermal reaction separation

[0048] The aluminum-silicon-sodium-calcium residue obtained by magnetic separation is subjected to a hydrothermal reaction in a NaOH-Ca(OH)2 composite system at a reaction temperature of 100℃ for 1h, and tobermorite and sodium aluminate solution are separated by filtration.

[0049] The iron grade of the red mud or tailings after iron selection in step S1 is 10wt.% to 60wt.%, the Al2O3 content is 5wt.% to 40wt.%, the SiO2 content is 3wt.% to 20wt.%, the CaO content is 0 to 20wt.%, and the Na2O content is 0 to 20wt.%.

[0050] The steel dust in step S2 is preferably a mixture of one or more of blast furnace gravity dust, blast furnace bag dust and blast furnace gas mud, and the iron grade is 15wt.% to 60wt.%, the carbon content is 5wt.% to 30wt.%, the Al2O3 content is 0 to 10wt.%, the SiO2 content is 0 to 15wt.%, the CaO content is 0 to 5wt.%, the Na2O content is 0 to 5wt.%, and the zinc content is 0 to 15wt.%.

[0051] The reducing agent in step S2 is a mixture of one or more of common reducing agents such as coke, anthracite, bituminous coal, lignite, semi-coke and biochar, and the additive in step S2 is a mixture of one or more of common sodium salts such as sodium carbonate, sodium sulfate, borax, sodium chloride and sodium hydroxide.

[0052] The iron grade of the iron powder product in step S3 is above 90wt.%, and the hydrothermal reaction system in step S2 has a CaO / SiO2 molar ratio of 0.5 to 2.0, a NaOH concentration of 5 to 50g / L, and a liquid-solid ratio of 10 to 50mL / g.

[0053] Although embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for synergistic disposal and utilization of red mud and steel dust, characterized in that, Specifically comprising the following steps: S1. Dry and finely grind Dry and finely grind the red mud to obtain a fine-grained powder material, with a particle size of <0.1 mm accounting for more than 70% by mass; S2. Mix and make into briquettes Mix and uniformly mix the finely ground red mud, steel dust, reducing agent, and additives in a mass ratio of 100:100:30:30 to make briquettes or pellets; S3. Roasting and grinding and separation Roast the briquettes or pellets at 800-1400℃ for 1-4h, collect the volatile matter to obtain zinc-rich dust, and separate the iron powder product and the aluminum-silicon-sodium-calcium-containing slag from the roasted material by grinding and magnetic separation; S4. Hydrothermal reaction and separation React the aluminum-silicon-sodium-calcium slag phase obtained by magnetic separation in a NaOH-Ca(OH)2 composite hydrothermal system at a reaction temperature of 100-400℃ for 1-4h, and separate tobermorite and sodium aluminate solution by filtration; The steel dust in step S2 is a mixture of one or more of blast furnace gravity dust, blast furnace bag dust, and blast furnace gas mud; The reducing agent in step S2 is a mixture of one or more of common reducing agents such as coke, anthracite, bituminous coal, lignite, semi-coke, and biochar; The additive in step S2 is a mixture of one or more of common sodium salts such as sodium carbonate, sodium sulfate, borax, sodium chloride, and sodium hydroxide; The hydrothermal reaction system in step S4 has a CaO / SiO2 molar ratio of 0.5-2.0, a NaOH concentration of 5-50g / L, and a liquid-solid ratio of 10-50mL / g.

2. A method for co-treatment and utilization of red mud and steel dust according to claim 1, characterized in that: The red mud in step S1 is the tailings obtained after iron is selected from red mud.

3. A method for co-treatment and utilization of red mud and steel dust according to claim 1, characterized in that: The iron powder product in step S3 has an iron grade of 90wt.% or higher.

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