High-iron red mud recycling method

Abstract

A kind of high-iron red mud recycling method, comprising the following steps: 1) take high-iron red mud, lime, after mixing, press into block raw material;2) after block raw material is dried, send into electric furnace, and add coke, auxiliary material;3) under the condition of oxygen deficiency, 1-10min, arc starting stage, voltage is 140-150V, current is 6000-12000A, 10-120min, smelting stage, voltage is 185-195V, current is 13000-16000A, 120-150min, refining stage, voltage is 150-170V, current is 16000-19000A;4) discharge, get molten iron and slag, upper layer slag is used as aluminate cement raw material, lower layer molten iron is used as cast iron raw material.The present application has simple process and low cost, can smelt high-iron red mud into molten iron and high-aluminum slag, change waste into treasure, make high-iron red mud get comprehensive utilization.

Description

Technical Field

[0001] This invention relates to the field of metallurgy, and in particular to a method for recycling high-speed iron red mud. Background Technology

[0002] Red mud is a solid waste generated during alumina production. my country produces over 100 million tons of red mud annually, with historical stockpiles exceeding 1 billion tons, which have remained largely unutilized. High-iron red mud is a potential iron source; however, compared to iron concentrate, it has a lower grade and contains sodium, making it unsuitable for direct use as raw material in ironmaking. Currently, it is typically utilized through magnetic separation for iron extraction or a pretreatment process involving reduction roasting followed by magnetic separation. Magnetic separation for iron extraction suffers from low recovery rates, low iron content in the product, and the need for landfill disposal of tailings. Reduction roasting followed by magnetic separation for iron extraction is costly and produces difficult-to-utilize magnetic separation tailings. If the red mud generated during alumina production is not effectively utilized, it will generate substantial amounts of industrial solid waste, impacting the environment without generating economic benefits.

[0003] Therefore, how to effectively recycle and utilize these high-iron red muds is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for recycling high-speed iron red mud. This method is simple and low-cost, and can smelt high-speed iron red mud into molten iron and high-alumina slag, turning waste into treasure and enabling the comprehensive utilization of high-speed iron red mud.

[0005] The technical solution of this invention is: a method for recycling high-speed iron red mud, comprising the following steps:

[0006] 1) Take high-iron red mud and lime, mix them, and press them into block-shaped raw materials;

[0007] 2) After drying the lumpy raw materials, they are fed into an electric furnace, along with coke and auxiliary materials;

[0008] 3) Under oxygen-deficient conditions, during the arc initiation and feeding stage (1-10 min), the voltage is 140-150V and the current is 6000-12000A; during the smelting stage (10-120 min), the voltage is 185-195V and the current is 13000-16000A; and during the refining stage (120-150 min), the voltage is 150-170V and the current is 16000-19000A.

[0009] 4) Discharge the material to obtain molten iron and slag. The upper slag is used as raw material for aluminate cement, and the lower molten iron is used as raw material for cast iron.

[0010] Furthermore, in step 1), bauxite is also added. The mass ratio of high-iron red mud to bauxite is 1:0.1-0.12. The bauxite has a particle size ≤40mm, a moisture content ≤2%, and SiO2 ≤5%.

[0011] Furthermore, the high-iron red mud mentioned in step 1) has a particle size ≤40mm and a moisture content ≤2%, and the lime has a moisture content ≤1% and SiO2 ≤2.6%.

[0012] Furthermore, in step 1), the weight ratio of high-speed iron red mud to lime is 1:0.1-0.15.

[0013] Furthermore, the auxiliary materials mentioned in step 2) are silica and lime. The mass ratio of the added coke to the high-iron red mud in the lumpy raw material is 0.23-0.3:1, the mass ratio of the added lime to the high-iron red mud is 0.1-0.15:1, and the mass ratio of the added silica to the high-iron red mud is 0.2-0.35:1.

[0014] Furthermore, in step 4), the upper slag is washed by high-pressure water through a flow channel to become water slag, which is used as a raw material for aluminate cement. The lower molten iron is then cast into shape and sold.

[0015] The above technical solution has the following beneficial effects:

[0016] 1. The recycling method of this invention first mixes high-iron red mud and lime, then presses them into block raw materials. This provides good kinetic conditions for the reduction reaction and exhibits good metallurgical properties. After reduction, it maintains a reasonable slag shape, facilitating slag formation and subsequent slag discharge. Furthermore, preparing the raw materials into block form effectively avoids material loss due to electric furnace dust extraction, improving the utilization rate of high-iron red mud. Then, it is dried to improve the permeability of the block raw materials and effectively reduce the adverse effects of moisture. The raw materials are then fed into an electric furnace with coke and auxiliary materials. The coke acts as a reducing agent, reducing the iron oxide in the high-iron red mud to elemental iron and generating carbon dioxide to form a protective atmosphere, preventing the oxidation of the molten iron obtained from reduction and improving the utilization rate of iron in the high-iron red mud. The silica in the auxiliary materials effectively lowers the melting point of the slag, preventing excessively high slag temperature and energy loss, thus reducing the power consumption for high-iron red mud recycling. In addition, the added silica also facilitates the discharge of the formed slag. In addition, it can ensure that the generated slag is mainly composed of aluminum oxide, calcium oxide and silicon dioxide, which can be directly used as raw material for high-alumina cement, effectively improving the utilization rate and recycling value of high-iron red mud.

[0017] 2. The recycling method of this invention also adds bauxite to the lumpy raw materials to increase the alumina content of the slag, meeting the alumina content requirements of high-alumina cement. It can be used directly as a raw material for high-alumina cement. Furthermore, the added bauxite also has a slag-forming effect.

[0018] 3. The recycling method of this invention controls the voltage at 140-150V and the current at 6000-12000A for 1-10 minutes during the feeding stage to preheat the raw materials; during the smelting stage, the voltage is 185-195V and the current is 13000-16000A for 120-150 minutes; and during the refining stage, the voltage is 150-170V and the current is 16000-19000A. ， During the smelting stage, the raw materials are in a solid state. By using high voltage and low current, multiple electric arcs are formed, which promotes the heating of the solid raw materials to carry out the reduction reaction. The iron obtained from the reduction is kept in a molten state. In the later stage, the raw materials are in a molten state and the conductivity is enhanced. By reducing the voltage and increasing the current, the amount of electric arc is reduced, while the resistance heat is increased, which can effectively improve the electrical efficiency of high-iron red mud recycling.

[0019] 4. The recycling method of this invention controls the mass ratio of high-iron red mud to lime to be 1:0.1-0.15. The purpose is to maintain a reasonable slag shape after reduction of the lumpy raw material, facilitating slag formation and subsequent slag discharge. By controlling the mass ratio of added coke to high-iron red mud in the lumpy raw material to be 0.23-0.3:1, the generation of carbon monoxide can be minimized while achieving the goal of reducing iron oxide.

[0020] The following is a further explanation of specific implementation methods. Detailed Implementation

[0021] In this invention, the high-iron red mud used is a solid waste generated by Chongqing Jiulong Wanbo New Material Technology Co., Ltd. during the production of alumina. The composition of the high-iron red mud is shown in the table below:

[0022]

[0023]

[0024] It is dried to a moisture content of less than 2% and used as raw material.

[0025] The method for recycling red mud from high-speed railways includes the following steps:

[0026] 1) Take high-iron red mud and lime according to the proportions in Table 2, mix them, and press them into block-shaped raw materials;

[0027] 2) After drying the lumpy raw materials, they are fed into an electric furnace, along with coke and auxiliary materials, as shown in Table 2.

[0028] 3) Under oxygen-deficient conditions, during the arc initiation and feeding stage (1-10 min), the voltage is 140-150V and the current is 6000-12000A; during the melting stage (10-120 min), the voltage is 185-195V and the current is 13000-16000A; and during the refining stage (120-150 min), the voltage is 150-170V and the current is 16000-19000A; this achieves the purpose of melting and sorting.

[0029] 4) Discharge the material to obtain molten iron and slag. The upper slag is used as raw material for aluminate cement, and the lower molten iron is used as raw material for cast iron. The results are shown in Tables 3 and 4, respectively.

[0030] Table 2

[0031]

[0032] Table 3

[0033]

[0034]

[0035] Table 4

[0036]

Claims

1. A method for recycling high-speed iron red mud, characterized in that, Includes the following steps: 1) Take high-iron red mud and lime, mix them and press them into block raw materials. The weight ratio of high-iron red mud to lime is 1:0.1-0.

15. Also add bauxite. The mass ratio of high-iron red mud to bauxite is 1:0.1-0.

12. The particle size of bauxite is ≤40mm, the moisture content is ≤2%, and the SiO2 is ≤5%. 2) After drying the lumpy raw materials, they are fed into an electric furnace, along with coke and auxiliary materials, namely silica and lime. The mass ratio of the coke added to the high-iron red mud in the lumpy raw materials is 0.23-0.3:1, the mass ratio of the lime added to the high-iron red mud is 0.1-0.15:1, and the mass ratio of the silica added to the high-iron red mud is 0.2-0.35:

1. 3) Under oxygen-deficient conditions, during the arc initiation and feeding stage (1-10 min), the voltage is 140-150V and the current is 6000-12000A; during the smelting stage (10-120 min), the voltage is 185-195V and the current is 13000-16000A; and during the refining stage (120-150 min), the voltage is 150-170V and the current is 16000-19000A. 4) Discharge the material to obtain molten iron and slag. The upper slag is used as raw material for aluminate cement, and the lower molten iron is used as raw material for cast iron.

2. The method for recycling high-speed railway red mud according to claim 1, characterized in that, Step 1) The high-iron red mud has a particle size ≤40mm and a moisture content ≤2%, while the lime has a moisture content ≤1% and SiO2 ≤2.6%.

3. The method for recycling high-speed iron red mud according to claim 1, characterized in that, Step 4) The upper layer of slag is washed by high-pressure water through a flow channel to become water slag, which is used as raw material for aluminate cement. The lower layer of molten iron is cast into shape and sold.

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