CN109913604B - Method for extracting iron from high-iron red mud and directly cementing - Google Patents

Abstract

A method for extracting iron from high-iron red mud and directly cementing the high-iron red mud comprises the following steps: (1) preparing high-iron red mud treated by a raw material calcification-carbonization method; (2) drying and dehydrating the raw materials, preparing a mixture with a solid carbonaceous reducing agent and a slagging agent, blowing the mixture to the vortex center of a vortex stirring high-temperature furnace, and carrying out vortex stirring reduction: (3) layering the formed molten iron and the molten slag, and performing overflow separation; adding ferrochromium and ferromanganese into molten iron to prepare wear-resistant cast iron; (4) adjusting the components of the molten slag to meet the requirements of cement clinker, and then cooling in air. The method of the invention has the advantages that the raw materials are not sintered, the additional value of the red mud utilization is increased, and the red mud utilization rate reaches 100 percent.

Description

Method for extracting iron from high-iron red mud and directly cementing

Technical Field

The invention relates to the technical field of environmental protection, in particular to a method for extracting iron from high-iron red mud and directly cementing the iron.

Technical Field

The red mud is strong alkaline solid waste generated after preparing aluminum oxide or aluminum hydroxide by taking bauxite as a raw material. Currently, worldwide red mud reserves are estimated to exceed 30 million tons and are growing at a rate of approximately 1.2 million tons per year, with a world red mud average utilization of 15%. The accumulated stock of Chinese red mud is increased to 6 hundred million tons and is increased at a rate of about 1 hundred million tons every year, and the utilization rate of Chinese red mud is only 4 percent. Most of the red mud is still disposed by adopting a land stockpiling method. The red mud piling not only wastes secondary resources and occupies a large amount of land, but also destroys the surrounding environment of the red mud yard, brings serious environmental problems, and causes the environmental protection pressure of the aluminum industry to increase dramatically. The environmental risk of red mud stacking has already attracted attention of governments and enterprises of alumina producing countries, and the key to solving the problem of red mud is to research and develop a comprehensive utilization technology of red mud.

In order to realize the efficient utilization of the red mud and the extraction of valuable elements, the aluminum industry of China carries out a great deal of research and development work, and the existing red mud utilization technology can be generally divided into two types: one method is used as a general industrial raw material and is invented by people of Zhao Guangming and the like, for example, a method for producing cement clinker by using red mud (application number: CN201210031710.1) is characterized in that dealkalized gypsum and fly ash are added into dealkalized red mud, the three materials are uniformly mixed in a stirring tank, water is added to adjust the concentration of the dealkalized red mud to 30 percent, a plate-frame high-pressure filter press is used for filter pressing until the water content of a solid mixture is lower than 25 percent, and then the solid mixture is sent into a rotary kiln to be calcined into the cement clinker; the invention relates to a process and a method for transforming all waste residues of an aluminum industrial process into ecological building materials (application number: CN200710105971), which are invented by Wangwangmao et al, and the waste residues of the aluminum industry in the production process are transformed into novel road materials and building wall materials by drying, crushing, reasonable proportioning, processing and forming (rolling and extruding) consolidation or sintering processes by utilizing the material properties of the solid waste red mud (sintering method and Bayer method), boiler slag, mineral processing tailings, chemical ash slag, coal gas generation slag and sludge produced in the production process.

There is also a technique for extracting valuable metal elements such as Na, Al, Fe, rare metals and the like from red mud; the invention relates to a dealkalization method of Bayer process red mud (application number: CN201810572642.7), which is invented by Luo Dongmen and the like, the red mud is firstly ground to update the surface of the red mud, then the red mud subjected to surface updating treatment is mixed with lime milk to carry out dealkalization reaction, the red mud slurry subjected to dealkalization reaction is washed and subjected to liquid-solid separation to obtain alkali-containing solution, the alkali-containing solution is returned to the alumina production flow, and the red mud with low alkali content after separation is sent to a red mud dam for stockpiling;

invented "Red mud from the Dongdong army, etcThe method for comprehensively recovering valuable metals such as iron, aluminum, scandium, titanium, vanadium and the like in the application No. CN201410121083.X mixes red mud with a reducing agent for reduction roasting to ensure that Fe₂O₃Conversion to Fe₃O₄Magnetic separation to obtain magnetic iron ore concentrate and non-magnetic product, dissolving out alumina from the non-magnetic product with ammonia water, mixing the washing slag with water to obtain ore pulp as absorbent for absorbing SO in coal-fired flue gas₂Adding high-concentration acid into washing slag for acidolysis, dissolving out scandium and titanium in acidolysis solution, filtering out acidolysis slag, adding metatitanic acid seed crystal into acidolysis solution, separating out titanium in the form of metatitanic acid through hydrolysis, using 13% P204, 7% TBP and 80% kerosene as extracting agents for acidolysis solution after extracting titanium, extracting scandium in solution, adding ammonia water for neutralization for solution after extracting scandium, and using 19% P204, 8% TBP and 73% kerosene as extracting agents for extraction to obtain vanadium.

When the red mud is used as a general industrial raw material, the problems of red mud alkalinity restriction, low product price, poor income and the like exist; the methods for respectively extracting valuable elements also have the problems of overlong treatment process flow, large wastewater quantity, unavailable tailings and the like. Zhang an 'a method for dissolving red mud' (application No. CN201110275030.X) is prepared by mixing Bayer process red mud with slaked lime, calcifying to dealkalize, and introducing CO into container₂Obtaining carbide slag with main components of calcium silicate, calcium carbonate and aluminum hydroxide, finally extracting the aluminum hydroxide by using a sodium hydroxide solution or a sodium aluminate solution, and changing the structure and the composition of the red mud through calcification transformation and carbonization transformation, thereby obtaining the calcification-carbonization red mud with the calcium silicate and the calcium carbonate as main phases.

Disclosure of Invention

In order to better realize the comprehensive utilization of the red mud, the invention provides a method for extracting iron from the high-iron red mud and directly cementing the high-iron red mud.

The technical scheme for realizing the invention is carried out according to the following steps:

(1)preparing high-iron red mud treated by a raw material calcification-carbonization method, wherein the raw material comprises 20-45% of Al by mass percent of TFe₂O₃ 8～12％，SiO₂ 5～20％，Na₂O 0.1～1.0％，H₂5-20% of O; and Al₂O₃With SiO₂The mass ratio A/S is 0.2-0.9;

(2) drying the raw material until the mass percent of water is less than or equal to 1 percent to obtain a dehydrated raw material; mixing a dehydration raw material, a solid carbonaceous reducing agent and a slagging constituent to prepare a mixture, directly blowing the mixture to the vortex center of a vortex stirring high-temperature furnace, rolling the mixture into a molten pool, and carrying out vortex stirring reduction for 10-60 min at 1300-1600 ℃; the solid carbonaceous reducing agent is coking coal, the molar ratio of the amount of the solid carbonaceous reducing agent to Fe in the raw material is 1.2-1.5, and the slagging agent is CaO and CaF₂Wherein CaO is added according to the alkalinity of the mixture of 1.0-1.4, and CaF₂10-30% of the total mass of CaO:

(3) layering molten iron and molten slag formed after reduction, and performing continuous overflow separation; adding ferrochromium and ferromanganese into the separated molten iron for direct smelting and casting to prepare a wear-resistant cast iron product;

(4) the components of the separated molten slag are adjusted in a smelting furnace to meet the requirements of cement clinker, then the molten slag is cooled to normal temperature by air, and then the molten slag is crushed and ground to prepare the cement clinker.

In the method, the alkalinity is calculated according to the following formula:

wherein mCaO is the mass of calcium oxide in the mixture, mAl₂O₃Is the mass of alumina in the mix, mSiO₂Is the mass of silica in the mixture.

In the above method, the main reaction formula involved in the reduction process is as follows:

Fe_xO_y+yC＝yCO+xFe (2)、

Fe_xO_y+yCO＝yCO₂+xFe (3)

and

Fe_xO_y+y/2C＝y/2CO₂+xFe (4)。

in the method, the recovery rate of the iron is more than or equal to 90 percent.

Compared with the prior art, the invention has the characteristics and beneficial effects that:

(1) the high-iron red mud treated by the calcification-carbonization method adopted by the raw materials belongs to low-alkali low-aluminum red mud, so that the limitation of alkali in the red mud on the production of cement clinker is eliminated, and the addition amount of the cement clinker fired by the red mud can be increased;

(2) the monomer dissociation degree of the iron-containing phase in the high-iron red mud treated by the calcification-carbonization method is high, so that the extraction of iron in the reduction process is facilitated, and the extraction rate of iron can reach more than 95%;

(3) vortex stirring, melting and reducing are adopted, raw materials do not need to be sintered, the raw materials can be directly fed into a furnace for reduction, and the reduction kinetic conditions are sufficient;

(4) the obtained molten iron is added with ferrochromium and ferromanganese to be directly smelted into wear-resistant cast iron, so that the additional value of red mud utilization is increased;

(5) the molten slag after reduction iron making can be directly added with regulating powder under the high-temperature vortex stirring, and can be directly made into cement clinker after cooling, crushing and grinding, the tailings are completely used for producing the cement clinker, and the utilization rate of the red mud reaches 100%.

Drawings

FIG. 1 is a schematic flow chart of the method for extracting iron from high-iron red mud and directly cementing the high-iron red mud.

Detailed Description

In the embodiment of the invention, the cement clinker comprises 62-64% of CaO and SiO by mass₂ 20～24％，Al₂O₃ 4.8～6％，Fe₂O₃ 2.5～3.2％。

The wear-resistant cast iron product in the embodiment of the invention is wear-resistant cast iron with the trade mark HBW555Cr13(ISO 21988/JN/HB).

In the embodiment of the invention, the high-iron red mud treated by the calcification-carbonization method is a dissolved slag formed by calcification, carbonization and aluminum dissolution of the Bayer process red mud in the invention patent of 'a method for dissolving red mud' (application number 201110275030, X), wherein the calcification temperature is 160 ℃, the carbonization temperature is 120 ℃, and the aluminum dissolution temperature is 60 ℃.

In the embodiment of the invention, the temperature of the raw material is 150-200 ℃ when the raw material is dried.

The vortex stirring reduction of the invention is a method disclosed by the invention of a vortex stirring smelting reduction iron-making method, and the related vortex stirring reduction high-temperature furnace is used as equipment for the method.

The invention discloses a vortex stirring smelting reduction iron making method, which is a patent application with a publication number of CN 106435080A.

The adjusting component in the embodiment of the invention is added with a calcareous raw material, a siliceous raw material and/or a ferrous raw material. The calcareous raw material is at least one of limestone and carbide slag; the siliceous raw material is at least one of kaolin, clay, fly ash and tailing slag; the iron raw material is at least one of high-iron red mud, iron slag and steel slag.

The present invention will be described in further detail with reference to examples.

Example 1

(1) Preparing high-iron red mud treated by a calcification-carbonization method of raw materials, wherein the raw materials comprise 45% of TFe and Na by mass percentage₂O 0.62％；A/S＝0.74；

(2) Drying the raw material until the mass percent of water is less than or equal to 1 percent to obtain a dehydrated raw material; mixing the dehydrated raw material with a solid carbonaceous reducing agent and a slagging constituent to prepare a mixture, directly blowing the mixture to the vortex center of a vortex stirring high-temperature furnace, rolling the mixture into a molten pool, and carrying out vortex stirring reduction for 60min at 1600 ℃; the solid carbonaceous reducing agent is coking coal, the molar ratio of the amount of the solid carbonaceous reducing agent to Fe in the raw material is 1.2, and the slagging agent is CaO and CaF₂In which CaO is added according to the basicity of the mixture of 1.0, CaF₂Accounting for 10 percent of the total weight of CaO:

(3) layering molten iron and molten slag formed after reduction, and performing continuous overflow separation; the recovery rate of iron is 95 percent; adding ferrochromium and ferromanganese into the separated molten iron, directly smelting, and casting to prepare ISO 21988/JN/HBW555Cr13 brand wear-resistant cast iron containing 13% of Cr and 1.1% of Mn;

(4) regulating the components of the separated molten slag in a smelting furnace to meet the requirements of cement clinker, then air-cooling to normal temperature, crushing and grinding to prepare the cement clinker, CaO and SiO₂、Al₂O₃And Fe₂O₃The contents of (A) are 64%, 20%, 6% and 2.5%, respectively.

Example 2

(1) Preparing high-iron red mud treated by a calcification-carbonization method of raw materials, wherein the raw materials comprise 20 mass percent of TFe and Na₂O 0.33％；A/S＝0.81；

(2) Drying the raw material until the mass percent of water is less than or equal to 1 percent to obtain a dehydrated raw material; mixing a dehydration raw material, a solid carbonaceous reducing agent and a slagging constituent to prepare a mixture, directly blowing the mixture to the vortex center of a vortex stirring high-temperature furnace, rolling the mixture into a molten pool, and carrying out vortex stirring reduction for 10-60 min at 1300 ℃; the solid carbonaceous reducing agent is coking coal, the molar ratio of the amount of the solid carbonaceous reducing agent to Fe in the raw material is 1.5, and the slagging agent is CaO and CaF₂In which CaO is added according to the basicity of the mixture of 1.4, CaF₂Accounting for 30 percent of the total weight of CaO:

(3) layering molten iron and molten slag formed after reduction, and performing continuous overflow separation; the recovery rate of iron is 90 percent; adding ferrochromium and ferromanganese into the separated molten iron, directly smelting and casting to prepare ISO 21988/JN/HBW555Cr13 wear-resistant cast iron containing 11% of Cr and 0.9% of Mn;

(4) regulating the components of the separated molten slag in a smelting furnace to meet the requirements of cement clinker, then air-cooling to normal temperature, crushing and grinding to prepare the cement clinker, CaO and SiO₂、Al₂O₃And Fe₂O₃The contents of (A) are respectively 62%, 24%, 6% and 3%.

Example 3

(1) Preparing high-iron red mud treated by a calcification-carbonization method of raw materials, wherein the raw materials comprise 32% of TFe and Na by mass percentage₂O 0.27％；A/S＝0.6；

(2) Drying the raw material until the mass percent of water is less than or equal to 1 percent to obtain a dehydrated raw material; mixing the dehydrated raw material with a solid carbonaceous reducing agent and a slag formerPreparing the materials into a mixture, directly blowing the mixture to the vortex center of a vortex stirring high-temperature furnace, rolling the mixture into a molten pool, and carrying out vortex stirring reduction for 10min at 1500 ℃; the solid carbonaceous reducing agent is coking coal, the molar ratio of the amount of the solid carbonaceous reducing agent to Fe in the raw material is 1.3, and the slagging agent is CaO and CaF₂In which CaO is added according to the basicity of the mixture of 1.2, CaF₂Accounting for 20 percent of the total weight of CaO:

(3) layering molten iron and molten slag formed after reduction, and performing continuous overflow separation; the recovery rate of iron is 91%; adding ferrochromium and ferromanganese into the separated molten iron, directly smelting and casting to prepare ISO 21988/JN/HBW555Cr13 wear-resistant cast iron containing 12% of Cr and 0.8% of Mn;

(4) regulating the components of the separated molten slag in a smelting furnace to make the molten slag meet the requirements of cement clinker, then air-cooling the molten slag to normal temperature, and crushing and grinding the molten slag to prepare the cement clinker CaO and SiO₂、Al₂O₃And Fe₂O₃The contents of (A) were 63%, 23%, 4.8% and 3.2%, respectively.

Claims (1)

1. A method for extracting iron from high-iron red mud and directly cementing the high-iron red mud is characterized by comprising the following steps of:

(1) preparing high-iron red mud treated by a calcification-carbonization method of raw materials, wherein the raw materials contain Al according to the mass percent of TFe 20 percent₂O₃ 8～12％，SiO₂ 5～20％，Na₂O 0.33％，H₂5-20% of O; and Al₂O₃With SiO₂The mass ratio of (A)/S is 0.81;

(2) drying the raw material until the mass percent of water is less than or equal to 1 percent to obtain a dehydrated raw material; mixing a dehydration raw material, a solid carbonaceous reducing agent and a slagging constituent to prepare a mixture, directly blowing the mixture to the vortex center of a vortex stirring high-temperature furnace, rolling the mixture into a molten pool, and carrying out vortex stirring reduction for 10-60 min at 1300 ℃; the solid carbonaceous reducing agent is coking coal, the molar ratio of the amount of the solid carbonaceous reducing agent to Fe in the raw material is 1.5, and the slagging agent is CaO and CaF₂In which CaO is added according to the basicity of the mixture of 1.4, CaF₂Accounting for 30 percent of the total weight of CaO:the alkalinity is calculated according to the formula:

wherein mCaO is the mass of calcium oxide in the mixture, mAl₂O₃Is the mass of alumina in the mix, mSiO₂The mass of the silicon oxide in the mixture;

(3) layering molten iron and molten slag formed after reduction, and performing continuous overflow separation; adding ferrochromium and ferromanganese into the separated molten iron for direct smelting and casting to prepare a wear-resistant cast iron product; the recovery rate of iron is 90 percent;

(4) the components of the separated molten slag are adjusted in a smelting furnace to meet the requirements of cement clinker, then the molten slag is cooled to normal temperature by air, and then the molten slag is crushed and ground to prepare the cement clinker.

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