A method for preparing coolant by synergistically using rotary hearth furnace return ore and secondary aluminum ash

Abstract

The present invention discloses a method for preparing a coolant by synergistically using return ore from a rotary hearth furnace and secondary aluminum ash. The return ore from the rotary hearth furnace, iron oxide scale, and secondary aluminum ash are mixed according to a proportion, and then a binder, bentonite, and water are added. After being fully stirred, a mixture is formed; the mixture is pressed into blocks, and after curing in a ventilated and dry place, a coolant is obtained. The coolant is directly used in the smelting of high-nitrogen steel in the converter, which solves the problem of difficult treatment in the secondary aluminum ash industry, while releasing the production capacity of the rotary hearth furnace and increasing the amount of dust and mud to be processed; the addition of secondary aluminum ash makes it easier to dissolve during the smelting process, solving the problem of difficulty in melting cold pressed blocks of return ore from a single rotary hearth furnace and iron oxide; and aluminum nitride and metallic aluminum react with oxygen in molten steel to generate aluminum oxide, which plays a role in deoxidation and nitrogenation; it reacts with calcium oxide in the return ore from the rotary hearth furnace to produce calcium aluminate, which plays a role in desulfurization slag, further broadening the application of waste.

Description

Technical Field

[0001] The present invention belongs to the field of high-value utilization of solid waste, and specifically relates to a method for preparing a coolant by synergistically using return ore from a rotary hearth furnace and secondary aluminum ash. Background Art

[0002] The Rotary Hearth Furnace (RHF) process is a typical direct reduction process used by major domestic steel mills to treat zinc-containing iron solid waste. It reduces the zinc-containing iron solid waste through a series of steps, including raw material pretreatment, batching, intensive mixing, pelletizing, and direct reduction in the RHF. This process produces metallized pellets with a high metallization rate. Zinc oxide powder is also recovered through a dust removal system. However, there has been no rational treatment for RHF return ore, which is typically directly reused, but this reuse is of low value and also squeezes the RHF's capacity for dust and sludge treatment.

[0003] The main harmful components in secondary aluminum ash are fluorides, chlorides, and nitrides. The large amount of aluminum nitride in secondary aluminum ash is highly permeable and reactive, reacting with water at room temperature to produce toxic and harmful ammonia with a strong irritating odor. This not only affects human health but also contributes to air pollution. Chlorides, fluorides, and heavy metals in aluminum ash have certain leaching toxicities. These harmful elements, when introduced into the soil, can easily cause soil salinization and groundwater contamination. Aluminum ash has an extremely fine particle size, which easily raises dust during storage, transportation, and handling, causing dust pollution.

[0004] Based on two difficult-to-treat solid wastes, a method of co-processing rotary hearth furnace return ore and secondary aluminum ash to prepare cold-pressed blocks for the smelting of converter high-nitrogen steel was proposed. While processing the two solid wastes, the elements in them can also be utilized, thereby increasing the added value. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a method for preparing a coolant by synergistically using the return ore from the rotary hearth furnace and secondary aluminum ash. By synergistically treating the secondary aluminum ash that is difficult to process industrially with the return ore from the rotary hearth furnace and preparing cold pressed blocks, the coolant can be used as a coolant in the smelting of high-nitrogen steel in the converter, thereby recycling the waste and broadening the application field.

[0006] In order to solve the problems of the prior art, the technical solution adopted by the present invention is:

[0007] A method for preparing a coolant by synergistically using rotary hearth furnace return ore and secondary aluminum ash comprises the following steps:

[0008] Step 1: Mix the rotary hearth furnace return ore, iron oxide scale, and secondary aluminum ash according to a ratio, then add a binder, bentonite, and water, and stir thoroughly to form a mixture;

[0009] Step 2: Press the mixture into blocks and cure them in a ventilated and dry place to obtain the coolant.

[0010] As an improvement, in step 1, the return ore from the rotary hearth furnace, iron oxide scale, and secondary aluminum ash are mixed in a mass ratio of 7:2:1-5:3:2, and then a binder with a mass fraction of 2-4%, a bentonite with a mass fraction of 4-6%, and water with a mass fraction of 8-10% are added for mixing.

[0011] It should be noted that the mass fractions of binder and bentonite are relative to the total mass of rotary hearth furnace return ore, iron oxide scale and secondary aluminum ash, and the mass fraction of water is relative to the total mass of rotary hearth furnace return ore, iron oxide scale, secondary aluminum ash, binder and bentonite.

[0012] As an improvement, the binder is a biological adhesive and the bentonite is sodium-based bentonite.

[0013] As an improvement, the size of the blocks pressed in step 2 is 10×10 cm-15×15 cm.

[0014] As an improvement, the curing time in step 2 is 4-7 days, and the curing conditions are ventilation and drying.

[0015] Reaction principle:

[0016] The return ore from the rotary hearth furnace, iron oxide scale and secondary aluminum ash are mixed and pressed into blocks. During the curing process, a certain proportion of water is added to the mixture, and the water will react with part of the aluminum nitride to generate aluminum hydroxide. The reaction formula is as follows.

[0017] AlN+H2O→Al(OH)3+NH3↑

[0018] Cold pressed blocks are added during steelmaking. Aluminum hydroxide decomposes under heat to form aluminum oxide. Aluminum nitride reacts with oxygen in molten steel to deoxidize it. At the same time, nitrogen enters the molten steel, increasing its nitrogen content. Calcium oxide in the rotary hearth furnace returns reacts with aluminum oxide to produce calcium aluminate, which helps desulfurization and slag reduction. The specific reaction equation is as follows:

[0019]

[0020] AlN+[O]→Al2O3+[N]

[0021] CaO+Al2O3→mCaO·nAl2O3

[0022] Beneficial effects:

[0023] Compared with the prior art, the method of co-processing the return ore from the rotary hearth furnace and the secondary aluminum ash of the present invention has the following advantages:

[0024] (1) Secondary aluminum ash is processed in conjunction with rotary hearth furnace return ore to prepare coolant for the smelting of high-nitrogen steel grades in converters, solving the difficult problem of secondary aluminum ash treatment in the industry, while releasing the production capacity of rotary hearth furnaces and increasing the dust and sludge treatment capacity;

[0025] (2) After curing for 5 days, the cold pressed blocks have an average compressive strength greater than 2500N and are added to the converter high nitrogen steel smelting as a coolant at a mass ratio of 3-5% of the converter charge. Due to the addition of secondary aluminum ash, the cold pressed blocks are easier to melt during the smelting process, solving the problem of difficulty in melting cold pressed blocks made of return ore and iron oxide from a single rotary hearth furnace. In addition, the aluminum nitride in the secondary aluminum ash and the metallic aluminum will react with the oxygen in the molten steel to form aluminum oxide, which plays a role in deoxidation and nitrogenation. The aluminum oxide will react with the calcium oxide in the return ore from the rotary hearth furnace to produce calcium aluminate, which plays a role in desulfurization slag. DETAILED DESCRIPTION

[0026] The following examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0027] Example 1

[0028] A method for preparing a coolant by synergistically using return ore from a rotary hearth furnace and secondary aluminum ash. The composition of the selected materials is as follows:

[0029] Table 1 Chemical composition of rotary hearth furnace return ore

[0030] Element type C <![CDATA[Fe2O3]]> <![CDATA[SiO2]]> MgO <![CDATA[Al2O3]]> CaO ZnO Mass fraction (%) 11.5 65.2 6.72 1.31 2.8 7.03 3.24

[0031] Table 2 Chemical composition of secondary aluminum ash

[0032] Element type Al AlN <![CDATA[Al2O3]]> <![CDATA[SiO2]]> MgO <![CDATA[Na2O]]> CaO F Cl Mass fraction (%) 6.7 10.2 58.3 10.7 5.4 3.2 1.3 1.4 2.8

[0033] Table 3 Chemical composition of iron oxide

[0034] Element type C <![CDATA[Fe2O3]]> <![CDATA[SiO2]]> MgO <![CDATA[Al2O3]]> CaO MnO Mass fraction (%) 0.207 97.6 0.977 0.088 0.346 0.242 0.238

[0035] The preparation method of the above-mentioned coolant comprises the following steps:

[0036] (1) Rotary hearth furnace return ore, iron oxide scale, and secondary aluminum ash were mixed in a mass ratio of 7:2:1, and then 3% by mass of a binder and 5% by mass of bentonite were added. Then, 8% by mass of water was added and mixed thoroughly to form a mixture. It should be noted that the mass fractions of the binder and bentonite are relative to the total mass of the rotary hearth furnace return ore, iron oxide scale, and secondary aluminum ash, and the mass fraction of water is relative to the total mass of the rotary hearth furnace return ore, iron oxide scale, secondary aluminum ash, binder, and bentonite.

[0037] (2) The mixed material was pressed into blocks of 15×15 cm and cured in a ventilated and dry place for 5 days. The mixed material was used as a coolant at a mass fraction of 4% of the converter charge and was directly used for converter high nitrogen steel smelting.

[0038] The average compressive strength of the cured cold-pressed blocks is 2800N. When added as coolants to the converter high-nitrogen steel smelting, the use of ammonia and nitrogen or ammonia-nitrogen mixed gas is reduced by 30%, the silicon manganese consumption is reduced from the original 1.2kg / t to 1.12kg / t, the ferrosilicon consumption is reduced from the original 0.72kg / t to 0.69kg / t, and the aluminum alloy consumption is reduced from the original 1.33kg / t to 1.25kg / t; the refined calcium carbide consumption is reduced from the original 0.27kg / t to 0.22kg / t, and the refined electric ash consumption is reduced from the original 1.8kg / t to 1.46kg / t. In summary, the use of ammonia and nitrogen or ammonia-nitrogen mixed gas is reduced by 30%, the use of deoxidizer is reduced by 15%, and the use of desulfurizer is reduced by 20%. The slagging effect is significantly improved compared to the cold-pressed blocks made of return ore and iron oxide from the single rotary hearth furnace.

[0039] Example 2

[0040] A method for preparing a coolant by synergistically using return ore from a rotary hearth furnace and secondary aluminum ash, the method comprising the following steps:

[0041] (1) Rotary hearth furnace return ore, iron oxide scale, and secondary aluminum ash were mixed in a mass ratio of 5:3:2, and then 3% by mass of a binder and 5% by mass of bentonite were added. Then, 8% by mass of water was added and mixed thoroughly to form a mixture. It should be noted that the mass fractions of the binder and bentonite are relative to the total mass of the rotary hearth furnace return ore, iron oxide scale, and secondary aluminum ash, and the mass fraction of water is relative to the total mass of the rotary hearth furnace return ore, iron oxide scale, secondary aluminum ash, binder, and bentonite.

[0042] (2) The mixed material was pressed into blocks of 15×15 cm and cured in a ventilated and dry place for 5 days. The mixed material was used as a coolant at a mass fraction of 4% of the converter charge and was directly used for converter high nitrogen steel smelting.

[0043] The average compressive strength of the cured cold-pressed blocks is 2900N. When added as coolants to the converter high-nitrogen steel smelting, the use of ammonia and nitrogen or ammonia-nitrogen mixed gas is reduced by 32%, the silicon manganese consumption is reduced from the original 1.2kg / t to 1.10kg / t, the ferrosilicon consumption is reduced from the original 0.72kg / t to 0.68kg / t, and the aluminum alloy consumption is reduced from the original 1.33kg / t to 1.23kg / t; the refined calcium carbide consumption is reduced from the original 0.27kg / t to 0.21kg / t, and the refined electric ash consumption is reduced from the original 1.8kg / t to 1.45kg / t. In summary, the use of ammonia and nitrogen or ammonia-nitrogen mixed gas is reduced by 32%, the use of deoxidizer is reduced by 17%, and the use of desulfurizer is reduced by 22%. The slagging effect is significantly improved compared to the cold-pressed blocks made of return ore and iron oxide from the single rotary hearth furnace.

[0044] Example 3

[0045] A method for preparing a coolant by synergistically using return ore from a rotary hearth furnace and secondary aluminum ash, the method comprising the following steps:

[0046] (1) Rotary hearth furnace return ore, iron oxide scale, and secondary aluminum ash were mixed in a mass ratio of 7:2:1, and then 2% by mass of a binder and 4% by mass of bentonite were added. Then, 9% by mass of water was added and mixed thoroughly to form a mixture. It should be noted that the mass fractions of the binder and bentonite are relative to the total mass of the rotary hearth furnace return ore, iron oxide scale, and secondary aluminum ash, and the mass fraction of water is relative to the total mass of the rotary hearth furnace return ore, iron oxide scale, secondary aluminum ash, binder, and bentonite.

[0047] (2) The mixed material was pressed into blocks of 12×12 cm and cured in a ventilated and dry place for 5 days. The mixed material was used as a coolant at a mass fraction of 4% of the converter charge and was directly used for converter high nitrogen steel smelting.

[0048] The average compressive strength of the cured cold-pressed blocks is 2600N. When added as coolant to the converter high-nitrogen steel smelting, the use of ammonia and nitrogen or ammonia-nitrogen mixed gas is reduced by 30%, the silicon manganese consumption is reduced from the original 1.2kg / t to 1.12kg / t, the ferrosilicon consumption is reduced from the original 0.72kg / t to 0.69kg / t, and the aluminum alloy consumption is reduced from the original 1.33kg / t to 1.25kg / t; the refined calcium carbide consumption is reduced from the original 0.27kg / t to 0.22kg / t, and the refined electric ash consumption is reduced from the original 1.8kg / t to 1.46kg / t. In summary, the use of ammonia and nitrogen or ammonia-nitrogen mixed gas is reduced by 30%, the use of deoxidizer is reduced by 15%, and the use of desulfurizer is reduced by 20%. The slagging effect is significantly improved compared with the cold-pressed blocks made of return ore and iron oxide from the single rotary hearth furnace.

[0049] Example 4

[0050] A method for preparing a coolant by synergistically using return ore from a rotary hearth furnace and secondary aluminum ash, the method comprising the following steps:

[0051] (1) Rotary hearth furnace return ore, iron oxide scale, and secondary aluminum ash were mixed in a mass ratio of 7:2:1, and then 3% by mass of a binder and 5% by mass of bentonite were added. Then, 8% by mass of water was added and mixed thoroughly to form a mixture. It should be noted that the mass fractions of the binder and bentonite are relative to the total mass of the rotary hearth furnace return ore, iron oxide scale, and secondary aluminum ash, and the mass fraction of water is relative to the total mass of the rotary hearth furnace return ore, iron oxide scale, secondary aluminum ash, binder, and bentonite.

[0052] (2) The mixed material is pressed into blocks of 15×15 cm and cured in a ventilated and dry place for 7 days. The mixed material is used as a coolant at a mass fraction of 4% of the converter charge and is directly used in the converter high nitrogen steel smelting.

[0053] The average compressive strength of the cured cold-pressed blocks is 2880N. When added as coolants to the converter high-nitrogen steel smelting, the use of ammonia and nitrogen or ammonia-nitrogen mixed gas is reduced by 30%, the silicon manganese consumption is reduced from the original 1.2kg / t to 1.12kg / t, the ferrosilicon consumption is reduced from the original 0.72kg / t to 0.69kg / t, and the aluminum alloy consumption is reduced from the original 1.33kg / t to 1.25kg / t; the refined calcium carbide consumption is reduced from the original 0.27kg / t to 0.22kg / t, and the refined electric ash consumption is reduced from the original 1.8kg / t to 1.46kg / t. In summary, the use of ammonia and nitrogen or ammonia-nitrogen mixed gas is reduced by 30%, the use of deoxidizer is reduced by 15%, and the use of desulfurizer is reduced by 20%. The slagging effect is significantly improved compared to the cold-pressed blocks made of return ore and iron oxide from the single rotary hearth furnace.

[0054] In summary, the present invention uses the synergistic treatment of secondary aluminum ash and rotary hearth furnace return ore to prepare coolant for the smelting of high-nitrogen steel in the converter, which solves the difficult treatment problems in the secondary aluminum ash industry, while releasing the production capacity of the rotary hearth furnace and increasing the dust and mud processing capacity, and has good application prospects.

Claims

1. A method for preparing coolant by synergistically using return ore from a rotary hearth furnace and secondary aluminum ash, characterized in that: The following steps are involved: Step 1: Mix the rotary hearth furnace return ore, iron oxide scale, and secondary aluminum ash according to a ratio, then add a binder, bentonite, and water, and stir thoroughly to form a mixture; Step 2: Press the mixture into blocks and cure them in a ventilated and dry place to obtain the coolant.

2. The method for preparing coolant by synergistically using return ore from a rotary hearth furnace and secondary aluminum ash according to claim 1, characterized in that: The binder is a biological adhesive, and the bentonite is sodium bentonite.

3. The method for preparing coolant by synergistically using return ore from a rotary hearth furnace and secondary aluminum ash according to claim 1, characterized in that: The size of the blocks pressed in step 2 is 10×10 cm to 15×15 cm.

4. The method for preparing coolant by synergistically using return ore from a rotary hearth furnace and secondary aluminum ash according to claim 1, characterized in that: The curing time in step 2 is 4-7 days, and the curing conditions are ventilation and dryness.

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