CN112375856B - Method for improving iron content of converter slag and nickel slag and/or copper slag by melt coupling modification - Google Patents

Method for improving iron content of converter slag and nickel slag and/or copper slag by melt coupling modification Download PDF

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CN112375856B
CN112375856B CN202011168603.4A CN202011168603A CN112375856B CN 112375856 B CN112375856 B CN 112375856B CN 202011168603 A CN202011168603 A CN 202011168603A CN 112375856 B CN112375856 B CN 112375856B
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王楠
陈敏
李小傲
信建疆
张春明
曹博文
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Northeastern University China
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B3/00—General features in the manufacture of pig-iron
    • C21B3/04—Recovery of by-products, e.g. slag
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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    • C04B7/147—Metallurgical slag
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B15/00—Other processes for the manufacture of iron from iron compounds
    • C21B15/02—Metallothermic processes, e.g. thermit reduction
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B15/00—Obtaining copper
    • C22B15/0026—Pyrometallurgy
    • C22B15/0056—Scrap treating
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B23/00—Obtaining nickel or cobalt
    • C22B23/02—Obtaining nickel or cobalt by dry processes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/001—Dry processes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/04—Working-up slag
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies

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Abstract

The invention discloses a method for improving iron content by melt coupling of converter slag and nickel slag and/or copper slag, which comprises the steps of discharging the molten converter slag with the slag temperature of not less than 1450 ℃ into a slag pot, and adding the nickel slag and/or the copper slag and aluminum ash into the slag pot under the stirring state of the molten converter slag to obtain molten and mixed slag; continuously stirring the molten and mixed slag to ensure that the nickel slag and/or the copper slag and the aluminum ash are/is fully mixed with the molten converter slag in the slag tank to complete the melt coupling modification and reduction reaction, and obtaining final molten slag containing a large amount of metallic iron drops; stopping stirring, naturally cooling the final molten slag in the slag tank to room temperature, taking out the metallic iron lumps settled at the bottom of the slag tank, and recovering the metallic iron in the tailings through magnetic separation. The method provided by the invention realizes the simultaneous dissociation of complex iron minerals in the converter slag and the nickel slag and/or the copper slag into simple iron oxides without additional supplementary heat, thereby promoting the co-extraction and recovery of iron resources in the multi-source metallurgical slag.

Description

Method for improving iron content of converter slag and nickel slag and/or copper slag by melt coupling modification
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a method for improving iron content by melt coupling modification of converter slag and nickel slag and/or copper slag.
Technical Field
With the rapid development of the nonferrous metallurgy industry in China, a large amount of nonferrous metallurgy slag is generated every year, wherein the total iron content in nickel slag and copper slag is about 30-45% and is higher than the recoverable grade of iron ore in China, and the extraction and recovery of iron resources in nickel slag and copper slag are beneficial to the development of iron ore resource channels in China and the promotion of the synergistic development of the iron and steel and nonferrous metallurgy industries. The iron in the nickel slag is mainly fayalite (2F)eO·SiO2) The iron-containing phase in the copper slag mainly exists in the form of fayalite and magnetite. Because the fayalite belongs to silicate minerals and is a stable and compact network structure formed by Si-O, iron resources in the nickel slag and the copper slag are difficult to directly recover. Therefore, when the iron resources in the nickel slag and the copper slag are extracted by adopting a high-temperature oxidation method or a reduction method, an alkaline modifier such as CaO is usually required to be added to promote the dissolution of the fayalite and release simple iron oxide (FeO), thereby promoting the deep extraction and recovery of the iron resources.
Converter slag is a byproduct of converter steelmaking, and has large production quantity and high alkalinity (binary alkalinity CaO/SiO)2About 3.0-4.0), iron-containing, etc. The total iron content in the converter slag can reach 15-25%, and the iron-containing phase is mainly calcium ferrite (2 CaO. Fe)2O3) Complex iron-containing minerals such as RO phase (solid solution formed by FeO, MgO and MnO) and the like exist; the calcium-containing minerals in the converter slag mainly comprise free calcium oxide (f-CaO) and tricalcium silicate (3 CaO. SiO)2) Dicalcium silicate (2 CaO. SiO)2) Etc.; the phosphorus-containing mineral phase in the converter slag is mainly dicalcium silicate (2 CaO. SiO)2) With tricalcium phosphate (Ca)3P2O8) The formed solid solution exists. At present, the comprehensive utilization rate of converter slag is less than 30%, and the main problems to be solved in the aspect of bulk resource utilization include: the hydration of free calcium oxide easily causes poor volume stability, the iron content causes poor grindability, and the phosphorus content limits the cyclic utilization in the steel process. In order to solve the above problems, it is common in the industry to add a siliceous modifier (silica or silica fume, fly ash, etc.) to the converter slag for the purpose of inerting the free calcium oxide; at the same time, the siliceous modifier can promote calcium ferrite (2 CaO. Fe) in the converter slag2O3) Dissociation into simple iron oxides (Fe)2O3) The method is beneficial to the extraction and recovery of iron resources in the converter slag, so that the converter slag with poor iron-containing grindability is converted into stable slag without iron and easy to grind, and the efficient cyclic utilization of the converter slag is realized.
Therefore, by means of the interactive reaction of calcium minerals such as free calcium oxide, tricalcium silicate, dicalcium silicate and calcium ferrite in the converter slag and fayalite in the nickel slag and/or the copper slag, the coupling modification between the converter slag and the nickel slag and/or the copper slag can be realized without an additional modifier, the aim of simultaneously dissociating the calcium ferrite in the converter slag and the fayalite in the nickel slag and/or the copper slag into simple iron oxides is fulfilled, and the joint extraction and recovery of iron resources in the converter slag and the nickel slag and/or the copper slag are promoted.
When the converter slag and the nickel slag and/or the copper slag are subjected to interactive reaction, the interactive reaction of the calcium-containing minerals and the fayalite is shown in formulas (1) to (6), namely, the free calcium oxide, the tricalcium silicate, the dicalcium silicate, the calcium ferrite and other calcium-containing minerals in the converter slag are subjected to coupling modification reaction with the fayalite in the nickel slag and/or the copper slag, so that the calcium ferrite in the converter slag and the fayalite in the nickel slag and/or the copper slag are simultaneously dissociated, and the simple Fe iron oxide is generated2O3And FeO.
CaO+2FeO·SiO2＝CaO·SiO2+2FeO (1)
2CaO+2FeO·SiO2＝2CaO·SiO2+2FeO (2)
1/2(3CaO·SiO2)+2FeO·SiO2＝3/2(CaO·SiO2)+2FeO (3)
2(3CaO·SiO2)+2FeO·SiO2＝3(CaO·SiO2)+2FeO (4)
2CaO·SiO2+2FeO·SiO2＝2(CaO·SiO2)+2FeO (5)
1/2(3CaO·Fe2O3)+2FeO·SiO2＝CaO·SiO2+2FeO+1/2Fe2O3 (6)
Therefore, the reducing agent is added into the coupling modified slag formed by the converter slag and the nickel slag and/or the copper slag, and FeO and Fe generated by the coupling modification reaction can be treated2O3And reducing the simple iron oxide to finally realize the co-extraction and recovery of iron resources in the coupling modified slag.
As the slag discharging temperature of the converter slag in the steel plant is usually over 1450 ℃, the sensible heat of each ton of slag is equivalent to 60kg of standard coal, and the converter slag is a high-quality high-temperature waste heat resource. If the doped nickel slag and/or copper slag is heated to a molten state by utilizing the physical sensible heat carried by the molten converter slag, the molten coupling modification of the converter slag and the nickel slag and/or the copper slag can be realized, and the modification efficiency is further improved.
However, because the physical sensible heat carried by the molten converter slag is limited, if the nickel slag and/or the copper slag are heated to a molten state only by utilizing the physical sensible heat of the molten converter slag, the amount of the nickel slag and/or the copper slag which can be mixed and melted by the molten converter slag is limited, so that the coupled modified slag cannot reach the target alkalinity, the complex iron oxide existing in the converter slag and the nickel slag and/or the copper slag cannot be completely dissociated, and the deep extraction and recovery of the iron resource in the modified slag are influenced finally. Therefore, in order to obtain the upgraded slag with the target basicity, additional heat is required to heat and melt more nickel slag and/or copper slag in addition to directly utilizing the physical sensible heat of the molten converter slag.
Therefore, a method for melt-coupled modification and co-iron extraction of converter slag and nickel slag and/or copper slag without heat supplementation is in need of development.
Disclosure of Invention
Aiming at the current technical situation of extraction of iron resources in converter slag, nickel slag and copper slag, the invention provides a method for extracting iron by fusion coupling modification of converter slag and nickel slag and/or copper slag, which realizes that complex iron minerals in converter slag and nickel slag and/or copper slag are simultaneously dissociated into simple iron oxides under the condition of not additionally supplementing heat, thereby promoting the joint extraction and recovery of iron resources in multi-source metallurgical slag.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
a method for improving iron content by fusion coupling of converter slag and nickel slag and/or copper slag comprises the following steps:
discharging the melting converter slag with the slag temperature of not less than 1450 ℃ into a slag pot, and adding nickel slag and/or copper slag and aluminum ash into the slag pot under the stirring state of the melting converter slag to obtain melt-mixed slag;
continuously stirring the molten and mixed slag to ensure that the nickel slag and/or the copper slag and the aluminum ash are/is fully mixed with the molten converter slag in the slag tank to complete coupling modification and reduction reaction, and obtaining final molten slag containing a large amount of metallic iron drops;
stopping stirring, naturally cooling the final molten slag in the slag tank to room temperature, taking out the metallic iron lumps settled at the bottom of the slag tank, and recovering the metallic iron in the tailings through magnetic separation.
Further, when discharging the melting converter slag with the slag temperature of not less than 1450 ℃ into a slag pot and adding nickel slag and/or copper slag and aluminum ash into the slag pot while the melting converter slag is in a stirring state, the method comprises the following steps:
after the melting converter slag with the slag temperature of not less than 1450 ℃ is discharged into a slag pot, nickel slag and/or copper slag and aluminum ash are mixed into the melting converter slag in batches, so that the temperature of the molten and mixed slag in the slag pot is maintained at 1400-1700 ℃.
Further, when nickel slag and/or copper slag and aluminum ash are incorporated into the molten converter slag by batch, the method includes:
and stirring the slag tank in a mechanical stirring manner to uniformly mix the nickel slag and/or the copper slag and the aluminum ash of each batch with the molten converter slag, wherein the mixing time interval between the nickel slag and/or the copper slag and the aluminum ash of two adjacent batches is 10-40 min.
Further, when two batches of nickel slag and/or copper slag and aluminum ash are mixed into the molten converter slag, the method comprises the following steps:
adding a first batch of nickel slag and/or copper slag and aluminum ash into a slag pot immediately after the molten converter slag is discharged into the slag pot; and after the first batch of nickel slag and/or copper slag and aluminum ash and the molten converter slag are continuously stirred for 30-40min, adding a second batch of nickel slag and/or copper slag and aluminum ash into the slag pot.
Further, the doping amount of the nickel slag and/or the copper slag in the first batch and the second batch is respectively 50-70% and 30-50% of the total doping amount of the nickel slag and/or the copper slag according to the mass ratio; the doping amount of the aluminum ash in the first batch and the second batch is respectively 50-70% and 30-50% of the total adding amount of the aluminum ash according to the mass ratio.
Further, when the metallic iron in the tailings is recovered by magnetic separation, the method comprises the following steps:
crushing the tailings to 10-400 mu m, and recovering the metallic iron in the tailings by magnetic separation.
Further, the total doping amount of the nickel slag and/or the copper slag is 60-120% of the mass of the molten converter slag, and the total doping amount of the aluminum ash is 30-40% of the total mass of the molten converter slag and the nickel slag and/or the copper slag.
Further, the particle size of the nickel slag and/or the copper slag is less than or equal to 5 mm; the aluminum ash is added into the slag pot in the form of aluminum ash balls, and the diameter of the aluminum ash balls is less than or equal to 10 mm.
Compared with the prior art of reducing and extracting iron resources in metallurgical slag, the method for improving the iron content of the converter slag and the nickel slag and/or the copper slag by melt coupling modification has the following advantages:
1) the method has the advantages that no extra modifier is added, and the fusion coupling modification of the converter slag and the nickel slag and/or the copper slag is realized to extract iron and jointly recover iron resources;
2) the coupling modification and the reduction iron extraction operation can be carried out by utilizing the slag pot in the converter slag-off process, and no extra disposal equipment is needed.
3) The heat requirements of melt coupling modification and reduction iron extraction are met by simultaneously utilizing the physical heat of the molten converter slag and the chemical heat of aluminothermic reduction reaction, and no additional heat is required;
4) the recovery rate of iron is high and can reach more than 93 percent;
5) alkalinity CaO/SiO of tailings after iron extraction20.75-1.5, can be used as a cement raw material, and realizes the maximum resource utilization.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
FIG. 1 is an XRD pattern of raw nickel slag of exemplary embodiments 1 to 3 of the present invention
FIG. 2 is an XRD pattern of raw converter slag of exemplary embodiments 1 to 3 of the present invention;
fig. 3 is an XRD pattern of the finally obtained tailings of exemplary examples 1 to 3 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The invention provides a method for improving iron content by melt coupling modification of converter slag and nickel slag and/or copper slag, which comprises the following steps:
(1) discharging the molten converter slag with the slag temperature of not less than 1450 ℃ into a slag pot, and adding nickel slag and/or copper slag with the total doping amount of 60-120% of the mass of the molten converter slag and aluminum ash with the total doping amount of 30-40% of the total mass of the molten converter slag and the nickel slag and/or the copper slag into the slag pot under the stirring state of the molten converter slag to obtain molten and mixed slag;
(2) continuously stirring the molten and mixed slag to ensure that the nickel slag and/or the copper slag and the aluminum ash are/is fully mixed with the molten converter slag in the slag tank to complete the melt coupling modification and reduction reaction, and obtaining final molten slag containing a large amount of metallic iron drops;
(3) stopping stirring, naturally cooling the final molten slag in the slag tank to room temperature, taking out the metallic iron lumps settled at the bottom of the slag tank, simultaneously crushing the tailings to 10-400 mu m, and recovering the metallic iron in the tailings through magnetic separation to finish the common iron extraction of the converter slag and the nickel slag and/or the copper slag.
The metallic aluminum is not only a strong reducing agent, but also the thermite reduction reaction is accompanied by a great deal of heat generation, and 1kg of the metallic aluminum releases about 17500kJ of heat for reducing the iron oxide. Therefore, when the metallic aluminum is used as a reducing agent to reduce the simple iron oxide released in the coupling modification, the exothermic heat of the thermite reaction can be fully utilized to provide heat compensation for the coupling modification and the common iron extraction process. And because the aluminum ash is metallurgical solid waste generated in the aluminum electrolysis and fusion casting processes, and the content of metallic aluminum in the aluminum ash is about 10-40 wt%, the aluminum ash is adopted to replace the metallic aluminum to be used as a reducing agent, so that the cost of the reducing agent can be reduced, more importantly, the coupling modification and reduction processes are thermally compensated by means of the chemical heat of the metallic aluminum in the aluminum ash for reducing iron oxide, the dual utilization of the physical sensible heat of the molten converter slag and the chemical heat of the aluminothermic reaction can be realized, the heat requirements of the molten modification and the molten reduction iron extraction are met, and the smooth proceeding of the coupling modification and the reduction iron extraction processes is ensured.
Therefore, the molten slag contains free calcium oxide (f-CaO) and tricalcium silicate (3 CaO. SiO)2Dicalcium silicate 2CaO SiO2Calcium ferrite 2 CaO. Fe2O3Calcium-containing minerals, and fayalite 2 FeO. SiO in nickel slag and/or copper slag2Under the slag discharging temperature of the molten converter slag and the heat provided by the chemical heat of the aluminothermic reduction reaction, the molten converter slag, the nickel slag and/or the copper slag are subjected to an interactive reaction, so that the calcium ferrite in the molten converter slag and the fayalite in the nickel slag and/or the copper slag are simultaneously dissociated, and Fe is released2O3And FeO, by simultaneous reaction of aluminum ash with Fe2O3And FeO to complete the reduction of iron oxide.
As a preferred embodiment, when the molten converter slag with the slag temperature of not less than 1450 ℃ is discharged into a slag pot, and nickel slag and/or copper slag and aluminum ash are added into the slag pot under the stirring state of the molten converter slag, the method comprises the following steps:
after the melting converter slag with the slag temperature of not less than 1450 ℃ is discharged into a slag pot, nickel slag and/or copper slag and aluminum ash are mixed into the melting converter slag in batches, so that the temperature of the molten and mixed slag in the slag pot is maintained at 1400-1700 ℃.
Because a large amount of heat is generated when the aluminum ash is used as a reducing agent to reduce the simple iron oxide released in the coupling modification, and the melt coupling modification iron extraction of the molten converter slag and the nickel slag and/or the copper slag needs to be carried out at the temperature of 1400-1700 ℃, the temperature of the molten mixed slag in the processes of the melt coupling modification and the reduction iron extraction of the converter slag and the nickel slag and/or the copper slag can be controlled between 1400-1700 ℃ by mixing the nickel slag and/or the copper slag and the aluminum ash into the molten converter slag in batches, and further the heat supplement of the slag tank from the outside is not needed.
Preferably, the slag pot is mechanically stirred when each batch of nickel slag and/or copper slag and aluminum ash is mixed into the molten converter slag, so as to promote the uniform distribution of the nickel slag and/or copper slag and the aluminum ash in the molten converter slag, and further promote the full progress of the coupling modification and reduction reaction. Meanwhile, the speed of coupling modification and reduction reaction can be controlled by controlling the rotating speed of mechanical stirring of the slag tank, so that the thermite reaction speed is controlled, and the temperature of the molten and mixed slag is controlled to be between 1400 ℃ and 1700 ℃.
Specifically, when nickel slag and/or copper slag and aluminum ash are mixed into the molten converter slag by a batch process, the method comprises the following steps:
and stirring the slag tank in a mechanical stirring manner to uniformly mix the nickel slag and/or the copper slag and the aluminum ash of each batch with the molten converter slag, wherein the mixing time interval between the nickel slag and/or the copper slag and the aluminum ash of two adjacent batches is 10-40 min.
After one batch of nickel slag and/or copper slag and aluminum ash are mixed into the molten converter slag, the slag pot is continuously mechanically stirred, so that the molten converter slag reacts with the batch of nickel slag and/or copper slag and aluminum ash for 10-40min, and then another batch of nickel slag and/or copper slag and aluminum ash are mixed into the molten converter slag, so that the temperature in the slag pot is controlled to be maintained at 1400-1700 ℃.
Further, when two batches incorporate nickel slag and/or copper slag and aluminum ash into the molten converter slag, it includes:
adding a first batch of nickel slag and/or copper slag and aluminum ash into a slag pot immediately after the molten converter slag is discharged into the slag pot; and after the first batch of nickel slag and/or copper slag and aluminum ash and the molten converter slag are continuously stirred for 30-40min, adding a second batch of nickel slag and/or copper slag and aluminum ash into the slag pot.
Wherein the doping amount of the nickel slag and/or the copper slag in the first batch and the second batch is respectively 50-70% and 30-50% of the total doping amount of the nickel slag and/or the copper slag according to the mass ratio; the doping amount of the aluminum ash in the first batch and the second batch is respectively 50-70% and 30-50% of the total adding amount of the aluminum ash according to the mass ratio.
As a preferred embodiment, the particle size of the nickel slag and/or the copper slag is less than or equal to 5 mm; the aluminum ash is added into the slag pot in the form of aluminum ash balls, and the diameter of the aluminum ash balls is less than or equal to 10 mm.
The following are examples of the present invention, and the chemical compositions of the slag, nickel slag and aluminum ash of the melting converter used in the examples are shown in tables 1 to 3, respectively.
TABLE 1 chemical composition of slag of melting converter used in examples
Figure BDA0002746559720000081
TABLE 2 chemical composition of nickel slag for examples
Figure BDA0002746559720000082
TABLE 3 chemical composition of aluminum ash for examples
Figure BDA0002746559720000083
Example 1
A method for improving quality and extracting iron by fusion coupling of converter slag and nickel slag comprises the following steps:
(1) discharging 25 tons of molten converter slag with slag temperature of 1600 ℃ into a slag pot, and adding a first batch of nickel slag with particle size less than or equal to 5mm and aluminum ash balls with diameter of 10mm into the slag pot to obtain initial-stage molten mixed slag; wherein the adding amount of the nickel slag is 19.6 tons, the adding amount of the aluminum ash balls is 14.7 tons, and the slag is continuously stirred and melted for 40 minutes by mechanical stirring after the first feeding;
(2) adding a second batch of nickel slag with the particle size less than or equal to 5mm and aluminum ash balls with the diameter of 10mm into the slag pot under the stirring state of the initial-stage melt-mixed slag to obtain middle-stage melt-mixed slag; wherein the adding amount of the nickel slag is 8.4 tons, and the adding amount of the aluminum ash balls is 6.3 tons;
(3) after the second charging, continuously stirring the middle-stage melt-mixed slag for 20 minutes to complete the coupling modification and reduction reaction of the nickel slag and the aluminum ash in a state of being fully mixed with the melt converter slag, wherein in the whole melt coupling modification and reduction process, the temperature of the melt-mixed slag in the slag pot is controlled at 1403-;
(4) stopping stirring, naturally cooling the final molten slag in the slag tank to room temperature, then tipping the slag tank, taking out the metallic iron lumps settled at the bottom of the slag tank, crushing the tailings to 50-100 mu m, and recovering the metallic iron in the tailings through magnetic separation.
The results of chemical composition measurement of metallic iron extracted by example 1 are shown in table 4, and contain 99.21% by mass of Fe, while the iron recovery rates of this example were 95.9% and 98.0% with respect to the original converter slag and nickel slag, respectively.
The results of measuring the chemical composition of the tailings obtained in example 1 are shown in Table 5, and the basicity of the tailings CaO/SiO2About 1.00, the main phase of the tailings is CaMg2Al16O27、MgAl2O4Thus, it can be seen that the tailings obtained in this example can be used as a cement raw material.
Example 2
A method for improving quality and extracting iron by fusion coupling of converter slag and nickel slag comprises the following steps:
(1) discharging 25 tons of molten converter slag with the slag temperature of 1500 ℃ into a slag pot, and then adding a first batch of nickel slag with the particle size of less than or equal to 4mm and aluminum ash balls with the diameter of 9mm into the slag pot to obtain initial-stage molten mixed slag; wherein the adding amount of the nickel slag is 11 tons, the adding amount of the aluminum ash balls is 8.8 tons, and the initial-stage melt-mixed slag is continuously stirred for 35 minutes by adopting mechanical stirring after the first feeding;
(2) adding a second batch of nickel slag with the particle size of less than or equal to 4mm and aluminum ash balls with the diameter of 9mm into the slag pot under the stirring state of the initial-stage melt-mixed slag to obtain middle-stage melt-mixed slag; wherein the adding amount of the nickel slag is 5 tons, and the adding amount of the aluminum ash balls is 7.2 tons;
(3) after the second charging, continuously stirring the medium-term melt-mixed slag for 25 minutes to complete the coupling modification and reduction reaction under the condition that the nickel slag and the aluminum ash are fully mixed with the melt converter slag, wherein the temperature of the melt-mixed slag in the slag tank is controlled at 1411-1685 ℃, and the final slag containing a large amount of metallic iron drops is obtained;
(4) stopping stirring, naturally cooling the final molten slag in the slag tank to room temperature, then tipping the slag tank, taking out the metallic iron lumps settled at the bottom of the slag tank, crushing the tailings to 50-100 mu m, and recovering the metallic iron in the tailings through magnetic separation.
The results of chemical composition measurement of metallic iron extracted by example 2 are shown in table 4, and contain 99.00% by mass of Fe, while the iron recovery rates of this example were 95.6% and 97.4% with respect to the original converter slag and nickel slag, respectively.
The results of measuring the chemical composition of the tailings obtained in example 2 are shown in Table 5, and the basicity of the tailings is CaO/SiO2About 1.25, the main phase of the tailings is Ca2Al2SiO7、MgAl2O4Thus, it can be seen that the tailings obtained in this example can be used as a cement raw material.
Example 3
A method for improving quality and extracting iron by fusion coupling of converter slag and nickel slag comprises the following steps:
(1) discharging 25 tons of melting converter slag with the slag temperature of 1450 ℃ into a slag pot, and then adding a first batch of nickel slag with the grain diameter less than or equal to 3mm and aluminum ash balls with the diameter of 8mm into the slag pot to obtain initial-stage melt-mixed slag; wherein the adding amount of the nickel slag is 7 tons, the adding amount of the aluminum ash balls is 4.8 tons, and the initial-stage melt-mixed slag is continuously stirred for 30 minutes by adopting mechanical stirring after the first feeding;
(2) adding a second batch of nickel slag with the particle size less than or equal to 3mm and aluminum ash balls with the diameter of 8mm into the slag pot under the stirring state of the initial-stage melt-mixed slag to obtain middle-stage melt-mixed slag; wherein the adding amount of the nickel slag is 8 tons, and the adding amount of the aluminum ash balls is 7.2 tons;
(3) after the second charging, continuously stirring the medium-term molten mixed slag for 30 minutes to complete the coupling modification and reduction reaction under the condition that the nickel slag and the aluminum ash are fully mixed with the molten converter slag, wherein in the whole coupling modification and reduction process, the temperature of the molten mixed slag in the slag pot is controlled to be 1422-1679 ℃, and the final slag containing a large amount of metallic iron drops is obtained;
(4) stopping stirring, naturally cooling the final molten slag in the slag tank to room temperature, then tipping the slag tank, taking out the metallic iron lumps settled at the bottom of the slag tank, crushing the tailings to 50-100 mu m, and recovering the metallic iron in the tailings through magnetic separation.
The chemical composition of metallic iron extracted by example 3 was measured as shown in table 4, and it contained 98.81% by mass of Fe, while the iron recovery rates of this example were 93.3% and 96.7% with respect to the original converter slag and nickel slag, respectively.
The results of measuring the chemical composition of the tailings obtained in example 3 are shown in Table 5, and the basicity of the tailings is CaO/SiO2About 1.25, the main phase of the tailings is Ca2Al2SiO7、MgAl2O4、CaMg2Al16O27、CaAl2Si2O8Thus, it can be seen that the tailings obtained in this example can be used as a cement raw material.
Table 4 composition of metallic iron extracted in examples 1 to 3
Figure BDA0002746559720000111
Table 5 tailings chemistries and iron recoveries in examples 1-3
Figure BDA0002746559720000112
Through the analysis of the above embodiment, compared with the existing reduction extraction technology of iron resources in metallurgical slag, the method for extracting iron by melt coupling modification of converter slag and nickel slag and/or copper slag provided by the invention has the following advantages:
1) the method has the advantages that no extra modifier is added, and the fusion coupling modification of the converter slag and the nickel slag and/or the copper slag is realized to extract iron and jointly recover iron resources;
2) the coupling modification and the reduction iron extraction operation can be carried out by utilizing the slag pot in the converter slag-off process, and no extra disposal equipment is needed.
3) The heat requirements of melt coupling modification and reduction iron extraction are met by simultaneously utilizing the physical heat of the molten converter slag and the chemical heat of aluminothermic reduction reaction, and no external heat supplementation is needed;
4) the recovery rate of iron is high and can reach more than 93 percent;
5) CaO/SiO alkalinity of tailings after iron extraction20.75-1.5, can be used as a cement raw material, and realizes the maximum resource utilization.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (7)

1. A method for improving quality and extracting iron by fusion coupling of converter slag and nickel slag and/or copper slag is characterized by comprising the following steps:
discharging the melting converter slag with the slag temperature of not less than 1450 ℃ into a slag pot, and adding nickel slag and/or copper slag and aluminum ash into the slag pot under the stirring state of the melting converter slag to obtain melt-mixed slag;
continuously stirring the molten and mixed slag to ensure that the nickel slag and/or the copper slag and the aluminum ash are/is fully mixed with the molten converter slag in the slag tank to complete the melt coupling modification and reduction reaction, and obtaining final molten slag containing a large amount of metallic iron drops;
stopping stirring, naturally cooling the final molten slag in the slag tank to room temperature, taking out the metallic iron lump settled at the bottom of the slag tank, recovering the metallic iron in the tailings through magnetic separation, and extracting the alkalinity CaO/SiO of the tailings after iron extraction20.75-1.5;
wherein, when the melting converter slag with the slag temperature of not less than 1450 ℃ is discharged into a slag pot and the nickel slag and/or the copper slag and the aluminum ash are added into the slag pot under the stirring state of the melting converter slag, the method comprises the following steps:
after the melting converter slag with the slag temperature of not less than 1450 ℃ is discharged into a slag pot, nickel slag and/or copper slag and aluminum ash are mixed into the melting converter slag in batches, so that the temperature of the molten and mixed slag in the slag pot is maintained at 1400-1700 ℃.
2. The method for improving the quality of the iron by the melt-coupling of the converter slag and the nickel slag and/or the copper slag according to claim 1, wherein when the nickel slag and/or the copper slag and the aluminum ash are mixed into the molten converter slag by batches, the method comprises the following steps:
and stirring the slag tank in a mechanical stirring manner to uniformly mix the nickel slag and/or the copper slag and the aluminum ash of each batch with the molten converter slag, wherein the mixing time interval between the nickel slag and/or the copper slag and the aluminum ash of two adjacent batches is 10-40 min.
3. The method for improving the quality of the iron by the fusion coupling of the converter slag and the nickel slag and/or the copper slag according to claim 2, wherein when two batches of the nickel slag and/or the copper slag and the aluminum ash are mixed into the molten converter slag, the method comprises the following steps:
adding a first batch of nickel slag and/or copper slag and aluminum ash into a slag pot immediately after the molten converter slag is discharged into the slag pot; and after the first batch of nickel slag and/or copper slag and aluminum ash and the molten converter slag are continuously stirred for 30-40min, adding a second batch of nickel slag and/or copper slag and aluminum ash into the slag pot.
4. The method for improving the quality of the iron by the melt-coupling of the converter slag and the nickel slag and/or the copper slag according to claim 3, wherein the mixing amount of the nickel slag and/or the copper slag in the first batch and the second batch is 50-70% and 30-50% of the total mixing amount of the nickel slag and/or the copper slag respectively according to the mass ratio; the doping amount of the aluminum ash in the first batch and the second batch is respectively 50-70% and 30-50% of the total adding amount of the aluminum ash according to the mass ratio.
5. The method for improving the quality of the iron by the melt coupling of the converter slag and the nickel slag and/or the copper slag according to claim 1, which is characterized by comprising the following steps when the metallic iron in the tailings is recovered by magnetic separation:
crushing the tailings to 10-400 mu m, and recovering the metallic iron in the tailings by magnetic separation.
6. The method for improving the quality of the iron by the fusion coupling of the converter slag and the nickel slag and/or the copper slag according to claim 1, wherein the total adding amount of the nickel slag and/or the copper slag is 60 to 120 percent of the mass of the molten converter slag, and the total adding amount of the aluminum ash is 30 to 40 percent of the total mass of the molten converter slag and the nickel slag and/or the copper slag.
7. The method for improving the quality and extracting the iron by the melt coupling of the converter slag and the nickel slag and/or the copper slag according to claim 1, wherein the particle size of the nickel slag and/or the copper slag is less than or equal to 5 mm; the aluminum ash is added into the slag pot in the form of aluminum ash balls, and the diameter of the aluminum ash balls is less than or equal to 10 mm.
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