Method of iron making from a mixture of various special iron ores

Abstract

The present application belongs to the technical field of smelting reduction ironmaking, and particularly relates to a smelting method of a mixture of multiple special iron ores. The method comprises the following steps: S1. mixing sea sand ore, high-phosphorus ore and red mud into a mixture according to a proportion; the mixing proportion is: sea sand ore (0-50%), high-phosphorus ore (0-50%): red mud (0-50%); S2. preheating the mixture; S3. feeding the preheated mixture into a smelting furnace for ironmaking. The innovation of the present application lies in solving the problem of large use of special iron ores, improving the use amount of special iron ores, realizing the utilization rate of resources, and achieving good economic benefits (the benefit per ton of iron can reach 526.73 yuan).

Description

Technical Field

[0001] This invention belongs to the field of molten reduction ironmaking technology, specifically relating to an ironmaking method using a mixture of various special iron ores. Background Technology

[0002] The special iron ore referred to here refers to iron-containing materials such as sea sand, red mud, and high-phosphate ore that cannot be used in large quantities in blast furnace ironmaking or that cannot produce qualified molten iron in a blast furnace.

[0003] Sea sand: Sea sand is a type of iron ore primarily found in the coastal areas of Southeast and South Asia, containing large reserves in countries such as New Zealand, Australia, India, and Sri Lanka. Sea sand is recognized both domestically and internationally as a difficult-to-smelt and beneficiate iron ore. Sea sand particles are relatively regular in shape, with smooth and dense surfaces, coarse particle size, and high hardness and melting point. After magnetic separation, sea sand contains over 50% iron and has a high TiO2 content (5%–12%), allowing it to be used only in small quantities for sintering and pelletizing. Global sea sand reserves are estimated at approximately 50 billion tons, but due to limitations in current ironmaking methods, large-scale mining has not been undertaken.

[0004] Red mud is an industrial solid waste generated during the production of alumina from bauxite, with a global annual production exceeding 70 million tons. After magnetic separation, red mud containing more than 45% iron and about 10% Al2O3 is obtained. However, due to its poor sintering performance when used as a sintering raw material in ironmaking, only a small amount is utilized, resulting in large-scale stockpiling. The treatment of red mud has become a major challenge for the industry.

[0005] High-phosphorus iron ore refers to iron ore with an iron content greater than 55% and a phosphorus content greater than 0.8%. my country's proven reserves of high-phosphorus iron ore are approximately 7.3 billion tons, mainly distributed in Hubei, Hunan, Jiangxi, Sichuan, Yunnan, Guizhou, Guangxi, and southern Gansu. Large quantities of high-phosphorus iron ore also exist in Northern Europe, Africa (Morocco and Algeria), and Australia. However, because there is currently no technology capable of smelting iron ore with a phosphorus content greater than 0.8% into usable molten iron, high-phosphorus iron ore has not been mined or utilized.

[0006] The above three types of special iron ores each have their own disadvantages: sea sand has high TiO2 and poor sintering properties; red mud has high Al2O3 and poor sintering properties; and high-phosphorus ores have high phosphorus content. Therefore, it is not possible to use a single ore for smelting or producing qualified molten iron.

[0007] Existing failures in blast furnaces and molten reduction furnaces (such as COREX and Finex furnaces) attempting to smelt single-specific ores (e.g., high phosphorus leading to substandard molten iron, high Al2O3) 3、 High TiO2 content leads to poor slag fluidity, both of which present significant technical challenges.

[0008] my country is a country lacking iron ore resources, importing over 1 billion tons of iron ore annually. The import price is around $120 per ton, reaching as high as $180 per ton at its peak. While the price of ordinary iron ore remains high, a large quantity of specialty iron ores are cheaper (approximately: red mud: 150 yuan / ton; sea sand: 450 yuan / ton; high-phosphate ore: 300 yuan / ton). However, due to the lack of suitable smelting technology, these ores remain unused, resulting in idle iron resources. Furthermore, the cost of ironmaking using imported ores is very high, currently leaving steel companies with virtually no profit.

[0009] The existing publicly available information does not provide solutions for the large-scale use of special iron ore. Summary of the Invention

[0010] Methods for solving technical problems:

[0011] Regarding the issue of large-scale use of special iron ore, after research, we propose the following solution:

[0012] A method for ironmaking from various special iron ore mixtures, including the following steps:

[0013] S1 Sea sand, high-phosphorus ore, and red mud are mixed in a certain proportion to form a mixture; the mixing ratio is: sea sand (0-50%), high-phosphorus ore (0-50%), and red mud (0-50%); the sum of the weight percentages of the three is 100%; the particle size of the mixture is <6mm;

[0014] S2 mixture preheating;

[0015] The preheated mixture (S3) is sent to the smelting furnace for ironmaking.

[0016] Furthermore, S1 may contain a certain proportion of ordinary iron ore powder (0-30%) or a certain proportion of other iron-containing materials, and the sum of the weight percentages of ordinary iron ore powder or other iron-containing materials and sea sand, high-phosphate ore and red mud is 100%.

[0017] Furthermore, the preferred ore blending ratio in S1 is: sea sand ore (30±5%), high-phosphorus ore (40±5%), and red mud (30±5%), with the sum of the weight percentages of the three ores being 100%.

[0018] Furthermore, 0.5% to 2% dolomite and 0.5% to 2% lime are added to S1.

[0019] Furthermore, the preheating of the mixture in S2 is carried out using a multi-stage fluidized bed or a multi-layer fluidized bed.

[0020] Furthermore, the preheating temperature of the mixture in S2 is 500℃~800℃.

[0021] Furthermore, the heat source for preheating the mixture in S2 is high-temperature coal gas generated during the ironmaking process.

[0022] Furthermore, the preheating and pre-reduction degree of the mixture in S2 is 10% to 30%.

[0023] Furthermore, the smelting furnace mentioned in S3 is a Hismelt furnace.

[0024] Furthermore, the preheated mixture is fed into the ore powder silo and then sent to the Hismelt furnace ore powder lance via the mixture injection system and injected into the molten pool; granular coal is sent to the Hismelt furnace granular coal lance via the injection system and injected into the molten pool; solvent is sent to the Hismelt furnace granular coal lance via the injection system and injected into the molten pool; oxygen-enriched hot air is injected into the Hismelt furnace through the hot air lance at the top; a reduction reaction occurs in the molten pool to generate iron, slag, and coal gas; the coal gas passes through the molten pool and enters the upper space to burn with oxygen in the hot air, and the heat released by the combustion heats the molten pool, providing heat for the molten pool reaction and slag-iron separation; the generated slag is discharged through the slag outlet, and the generated iron is discharged through the preheater.

[0025] This invention provides a method for ironmaking using a mixture of various special iron ores. The mixed use of different special ores offsets the defects of a single ore, solves the problem of large-scale use of special iron ores, increases the amount of special iron ores used, realizes resource utilization, and can achieve good economic benefits (the benefit per ton of iron can reach 526.73 yuan). Attached Figure Description

[0026] Figure 1 This is a schematic flowchart of a method according to an embodiment of the present invention. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0028] Example 1

[0029] Specifically, ironmaking methods for various special iron ore mixtures include:

[0030] 1) Raw material conditions:

[0031]

[0032] Composition and proportions of various special minerals:

[0033] Particle coal composition

[0034]

[0035] 2) Ironmaking methods using mixtures of various special iron ores

[0036] S1 Mixing process: Mix sea sand (30%), high-phosphate ore (40%), and red mud (30%), and add 0.5% to 1% dolomite. Then, mix the mixture in a high-power mixer. The mixed material is then sent to the preheating process.

[0037] S2 The mixture from the mixing process enters the buffer silo and is fed into the fluidized bed by the quantitative feeding device under the silo; the high-temperature gas (850℃, containing about 30% (CO+H2)) from the smelting furnace is sent to the inlet chamber at the bottom of the multi-layer fluidized bed, and after the air volume is evenly distributed by the fluidized bed air distribution plate, it enters the fluidized bed layer; in the fluidized bed layer, the high-temperature gas exchanges heat with the mixture, heating and pre-reducing the mixture, and the mixture is heated to 800℃ with a pre-reduction degree of 10%; the preheated and pre-reduced mixture is discharged from the fluidized bed and sent to the hot mixture silo.

[0038] A mineral powder injection system is installed below the S3 hot mixing bin. The mixture is quantitatively fed into the molten pool via the injection system through the mineral powder injection lance of the Hismelt furnace. Particle coal is also injected into the molten pool through the injection system through the particle coal injection lance of the Hismelt furnace. Solvents (such as lime) are injected into the molten pool through the injection system through the particle coal injection lance of the Hismelt furnace. Oxygen-enriched hot air is injected into the Hismelt furnace through the hot air lance at the top. A reduction reaction occurs in the molten pool to produce iron, slag, and gas. The gas passes through the molten pool into the upper space and burns with oxygen in the hot air. The heat released from the combustion heats the molten pool, providing heat for the molten pool reaction and slag-iron separation. The generated slag is discharged through the slag outlet, and the generated iron is discharged through the preheating furnace. The molten iron discharged from the furnace is placed in a ladle and undergoes desulfurization treatment by the desulfurization system. Qualified molten iron is sent to the iron casting machine or steelmaking.

[0039] Part of the gas produced by the Hismelt furnace is used to heat the oxygen-enriched air in the hot blast stove, and the other part is used for gas-fired power generation. The power generated can meet the electricity needs of the ironmaking system equipment such as oxygen production and blast furnace.

[0040] The flue gas produced by coal gas combustion is discharged after being desulfurized by the lime method.

[0041] Ironmaking using a mixture of various special iron ores: TiO2 from sea sand and Al2O3 from red mud form a composite slag phase that lowers the melting point; the mixed application of high-phosphorus ores with sea sand and red mud reduces the phosphorus load entering the furnace; phosphorus is converted into stable phosphate in the high-FeO content slag and solidified in the slag, thus synergistically achieving dephosphorization and the smelting of qualified molten iron.

[0042] Composition of molten iron:

[0043]

[0044] The economic benefits of constructing a 5 million-ton-capacity ironmaking plant using this ironmaking method, with 5 Hismelt furnaces, are calculated as follows:

[0045]

[0046] If a smelter with an annual output of 5 million tons is built, it can consume 2.77 million tons of red mud, 3.7 million tons of high-phosphate ore, and 2.77 million tons of sea sand ore annually, with an annual benefit of 2.66 billion yuan.

[0047] Good economic benefits can drive the construction of large-scale plants using this technology, and the extensive use of special iron ore, thus alleviating the pressure of importing large quantities of iron ore from countries such as Australia and Brazil.

[0048] Compare the core differences between this invention and existing technologies:

[0049] Innovative ore blending: By synergistically combining three special ores in varying proportions, the defects of a single ore are offset (complementary combination of high TiO2, high Al2O3, and high phosphorus).

[0050] Process innovation: fluidized bed preheating (500℃~800℃) + pre-reduction degree control (10%~30%), adapted to the melting reduction characteristics of the Hismelt furnace;

[0051] Resource and economic innovation: For the first time, large-scale utilization of three types of industrial solids / refractory ores was achieved, with a profit of 526.73 yuan per ton of iron, alleviating dependence on imported ores.

[0052] Example 2

[0053] Mixing ratio of several minerals:

[0054] Sea sand (50%), high-phosphate ore (50%), red mud (0%)

[0055] Example 3

[0056] Mixing ratio of several minerals:

[0057] Sea sand (0%), high-phosphate ore (60%), red mud (40%)

[0058] Example 4

[0059] Mixing ratio of several minerals:

[0060] Sea sand ore (35%), high-phosphate ore (40%), and common iron ore (25%)

[0061] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for ironmaking from a mixture of various special iron ores, characterized in that, Includes the following steps: S1 sea sand, high-phosphate ore, and red mud are mixed in a certain proportion to form a mixture; The proportions are within the following range: sea sand (0-50%), high-phosphate ore (0-50%), and red mud (0-50%), with the sum of the weight percentages of the three being 100%; the particle size of the mixture is <6mm; S2 mixture preheating; The preheated mixture (S3) is sent to the smelting furnace for ironmaking.

2. The ironmaking method of a mixture of various special iron ores as described in claim 1, characterized in that, The S1 may also contain a certain proportion of ordinary iron ore powder (0-30%), or a certain proportion of other iron-containing materials, and the sum of the weight percentages of ordinary iron ore powder or other iron-containing materials and sea sand, high-phosphate ore and red mud is 100%.

3. The ironmaking method of a mixture of various special iron ores as described in any one of claims 1 and 2, characterized in that, The preferred ore blending ratio in S1 is: sea sand ore (30±5%), high-phosphorus ore (40±5%), and red mud (30±5%), with the sum of the weight percentages of the three ores being 100%.

4. The ironmaking method of a mixture of various special iron ores as described in any one of claims 1, characterized in that, In addition, 0.5% to 2% dolomite and 0.5% to 2% lime are added to S1.

5. The ironmaking method of a mixture of various special iron ores as described in claim 1, characterized in that, The preheating of the mixture in S2 is carried out using a multi-stage fluidized bed or a multi-layer fluidized bed.

6. The ironmaking method of a mixture of various special iron ores as described in any one of claims 1 and 5, characterized in that, The preheating temperature of the mixture in S2 is 500℃~800℃.

7. The ironmaking method of a mixture of various special iron ores as described in any one of claims 1 and 6, characterized in that, The heat source for preheating the mixture in S2 is high-temperature coal gas generated during the ironmaking process.

8. The ironmaking method of a mixture of various special iron ores as described in any one of claims 1 and 7, characterized in that, The preheating and pre-reduction degree of the mixture in S2 is 10% to 30%.

9. The ironmaking method of a mixture of various special iron ores as described in claim 1, characterized in that, The smelting furnace mentioned in S3 is a Hismelt furnace.

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