CN111748686A - Process for producing metallized furnace charge by directly reducing nonferrous smelting slag - Google Patents
Process for producing metallized furnace charge by directly reducing nonferrous smelting slag Download PDFInfo
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- 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
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/242—Binding; Briquetting ; Granulating with binders
- C22B1/243—Binding; Briquetting ; Granulating with binders inorganic
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0066—Preliminary conditioning of the solid carbonaceous reductant
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0073—Selection or treatment of the reducing gases
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/008—Use of special additives or fluxing agents
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
- C21B13/105—Rotary hearth-type furnaces
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- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/02—Roasting processes
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/2406—Binding; Briquetting ; Granulating pelletizing
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- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B5/00—General methods of reducing to metals
- C22B5/02—Dry methods smelting of sulfides or formation of mattes
- C22B5/10—Dry methods smelting of sulfides or formation of mattes by solid carbonaceous reducing agents
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Abstract
The invention discloses a process for producing a metallized furnace charge by directly reducing nonferrous smelting slag, which is used for producing the metallized furnace charge by fully utilizing the nonferrous smelting slag and comprises the following steps: dry-grinding the nonferrous smelting slag to the granularity of 300 meshes below which the nonferrous smelting slag accounts for more than 85 percent, and mixing the nonferrous smelting slag, the high-volatile coal, the binder, the focusing agent and the liquid-phase modifying agent according to the proportion of 100: 20-28: 1-5: 5-13: 1-2, mixing, pelletizing, heating the pellets in a rotary hearth furnace to raise the temperature, and fully pyrolyzing the coal to generate H2And with H2H is generated by carbon gasification reaction with O as gasification agent2Reducing iron oxide, controlling the temperature of a hearth to 1250-1280 ℃ and the roasting time to 28-35 min, so that the colored iron oxide can be obtainedThe smelting slag is fully reduced. The invention can efficiently reduce the metal in the nonferrous smelting slag, and the process has the advantages of high heat transfer efficiency, high reduction speed, high productivity and reduced discharge.
Description
Technical Field
The invention belongs to the technical field of metallurgy and mineral engineering, and particularly relates to a process for producing a metallization furnace material by directly reducing nonferrous smelting slag.
Background
In the non-ferrous smelting process, a large amount of nickel smelting slag and copper smelting slag can be produced, the nickel smelting system can produce nickel flash slag, nickel sedimentation slag and nickel depletion slag, and the copper smelting system can produce synthetic slag.
In the production of pyrometallurgical copper smelting, the copper slag is the tailings discarded after copper selection in copper smelting, and the slag of the copper smelting belongs to FeO-Fe304-SiO2The main mineral composition of the ternary slag system is 2FeO2. The iron in the copper slag is mainly fayalite (Fe)2SiO4) The form of (2) exists, and the recovery difficulty is extremely high. When the direct ore dressing or the oxidation modification method is adopted to extract iron, the iron recovery rate is very low due to the lower magnetism of the copper slag, and when the copper slag is extracted by the smelting reduction method, the production energy consumption and the production cost are higher. In order to dispose the copper slag, some enterprises sell the copper slag to cement plants as admixture, and some enterprises adopt a direct stockpiling mode. Resulting in long-term piling up of a large amount of copper tailings, not only occupying land, but also causing waste and loss of valuable resources such as iron, zinc and the like in the copper tailings, and causing serious pollution to underground water, soil and atmosphere.
Among the nickel smelting furnace slag, the nickel smelting furnace slag belongs to FeO-MgO-SiO2The main mineral composition of the ternary slag system is 2FeO2、FeO.SiO2And MgO. SiO2。
The following table shows the chemical composition (unit:%) of the slag from the copper-nickel smelting furnace
| Name (R) | Ni | Cu | Fe | Co | S | CaO | MgO | SiO2 |
| Nickel slag | 0.21 | 0.24 | 42.24 | 0.09 | 0.78 | 2.10 | 8.85 | 32.81 |
| Copper slag | 0.04 | 0.79 | 44.17 | 0.00 | 0.83 | 2.14 | 1.67 | 35.71 |
When non-ferrous smelting is treated by a direct reduction process, because the oxidation degree of high-temperature copper-nickel slag discharged from a smelting furnace is insufficient in the natural cooling and spray cooling processes, iron in the non-ferrous smelting slag mainly exists in the form of ferric silicate, and a large amount of SiO is mixed between fine iron compound particles2Particles of Fe in3O4Content (wt.)Is very low. Because the melting point of the iron silicate is lower, liquid phase is easily generated on the surface of the material in the high-temperature reduction process of the nonferrous smelting slag, so that the nonferrous smelting slag is difficult to reduce at high temperature.
In nonferrous smelting slag, the iron grade is about 40%, but the comprehensive utilization of the nonferrous smelting slag is difficult. Firstly, the artificial silicate minerals are difficult to enrich through mineral separation methods such as magnetic separation and the like, when the reduced metallized pellets are used for producing iron powder through a grinding and selecting process, the separation of iron and gangue minerals can be realized only by grinding the granularity of the metallized pellets to be small, and the finer grinding granularity brings great difficulty to the magnetic separation process. Secondly, iron mainly exists in the slag in the form of silicate iron, Si contained in the slag is a harmful element in the steelmaking process, and Cu contained in the slag enters molten iron along with Ni and Co in the reduction process, so that difficulty is brought to selection of subsequent products.
At present, the method for extracting iron by using nonferrous smelting slag mainly comprises the following four methods: magnetic separation iron extraction of nonferrous smelting slag, oxidation modification iron extraction of nonferrous smelting slag, smelting reduction iron extraction of nonferrous smelting slag, direct reduction iron extraction of nonferrous smelting slag, and the like. (1) And carrying out magnetic separation on the nonferrous smelting slag to extract iron. Because the content of magnetic iron oxide in the nonferrous smelting slag is low and only accounts for 5-15%, the main iron-containing phases are silicate phases such as non-magnetic fayalite and the like, and the silicate phases completely enter tailings in the magnetic separation and flotation processes, a large amount of mineral tailings can be generated, and the metal recovery rate of the magnetic separation is low. (2) Oxidizing and modifying the nonferrous smelting slag to extract iron. The content of fayalite in the nonferrous smelting slag is high, and the high-temperature slag discharged from the flash smelting furnace is naturally oxidized in the air, so that part of fayalite is oxidized into Fe3O4And SiO2. Because the fayalite in the nonferrous smelting slag is in a compact liquid phase, the natural oxidation effect of the slag after the slag is discharged is poor, and the magnetic separation characteristic of the nonferrous smelting slag is poor. (3) And (4) smelting and reducing nonferrous smelting slag to extract iron. The smelting reduction process is that non-ferrous smelting slag and coal are mixed and agglomerated, lump materials are added into a submerged arc furnace for smelting reduction, lime is added to adjust the alkalinity, and reduced molten iron can be smelted. The process has the advantages of low iron grade in the raw material slag, high iron extraction cost of non-ferrous smelting slag by smelting reduction, and reducing agentAnd the consumption of the fusing agent is high, and the production energy consumption is high. (4) The nonferrous smelting slag is directly reduced to extract iron. In the coal-based direct reduction of the nonferrous smelting slag, carbon is used as a reducing agent to reduce the nonferrous smelting slag, and the carbon gasification temperature in coal is above 1300 ℃, so that the reduction temperature of the nonferrous smelting slag is higher, the softening temperature of fayalite is reached, and a liquid phase is generated on the surface of the nonferrous smelting slag, so that the reduction reaction of an iron compound is difficult to continue, the metallization rate of a reduced material is low, the iron grade of a ground product is low, and the metal recovery rate is low.
Carbon metallurgy is a typical process of traditional development in the steel industry, the reducing agent being carbon and the end product being carbon dioxide. The hydrometallurgical reducing agent is hydrogen, the final product is water, and zero emission of carbon dioxide is realized. The traditional direct reduction process mainly utilizes CO as a reducing agent and uses CO to remove oxygen in iron ore. The molecules of CO are large, so that the CO is difficult to permeate into the iron ore. And H2Has the smallest molecular weight and the smallest molecular diameter, and can easily permeate into the iron ore. Normally, H in ore2Has a permeation rate 5 times that of CO, H2Has a reduction potential 11 times that of CO. Thus, the use of hydrogen as a reductant can multiply the metallurgical reduction efficiency compared to conventional carbonaceous reductants.
The hydrogen metallurgy mainly uses H in the iron ore smelting process2As reducing agent, H2As an active reducing agent, when the reducing agent participates in the gas-solid reduction reaction of iron oxide in a furnace, the main products are metallic iron and water vapor, and the tail gas after reduction can not cause pollution to the environment. Therefore, the hydrogen metallurgy is vigorously developed, the reduction efficiency of the iron ore can be greatly improved, the consumption of the carbon reducing agent in the smelting process is reduced, and the pollution to the environment is reduced.
Large amount of hydrogen is consumed in the metallurgical process, and H needs to be produced in advance2Then adding H2Through storage and transport, thus enabling economical supply of H2Is the premise and the basis of the development of the hydrogen metallurgy process. At present, there are 4 methods for large-scale hydrogen production: coal gasification hydrogen production, natural gas cracking hydrogen production, petroleum gasification and cracking hydrogen production and waterHydrogen is produced by electrolysis. In addition, the coke oven gas is also the gas of choice for preparing hydrogen in large quantities at low cost. Due to the limitation of production cost, the above various hydrometallurgical processes are only based on laboratory tests and mechanism researches, and have no application examples in the aspect of industrialization.
Disclosure of Invention
According to the situation, the invention aims to solve the problems of high reduction temperature, long reduction time, low metallization rate of reduced materials, low iron grade of ground products and low metal recovery rate in the direct reduction process of nonferrous smelting slag, and the H is safely and economically produced2And is combined with H2The invention provides a process for producing a metallization furnace material by directly reducing nonferrous smelting slag.
Therefore, the invention adopts the following technical scheme:
a process for producing a metallized furnace material by directly reducing nonferrous smelting slag comprises the following steps:
s1 raw materials are selected as follows: the raw materials are 38-44% in grade and SiO2The content of the nonferrous smelting slag is 30-40%, the granularity is less than 10mm, and the fuel and the reducing agent adopt high-volatile coal;
and (S2) drying the material: respectively drying the nonferrous smelting slag and the high-volatile coal to remove water carried in the materials;
s3 grinding the materials: grinding the nonferrous smelting slag to below 300 meshes and accounting for more than 85 percent, and grinding the high-volatile coal to below 200 meshes and accounting for more than 80 percent;
preparation of S4 carbon-containing pellets: selecting 100 parts of colored smelting slag, 20-28 parts of high-volatile coal, 1-5 parts of binder, 5-13 parts of focusing agent and 1-2 parts of liquid-phase modifying agent according to parts by weight, mixing uniformly, adding water to prepare wet pellets with the particle size of 15-25 mm, and drying the wet pellets;
s5 rotary hearth furnace burden distribution: paving the dried pellets to the bottom of a rotary hearth furnace, wherein the paving thickness is 50-70 mm;
s6 roasting: controlling the temperature of a hearth to 1250-1280 ℃ and the roasting time to be 28-35 min, so that the nonferrous smelting slag is reduced in the furnace;
s7 discharging: the pellets reach a discharging area of the rotary hearth furnace, are continuously discharged through a discharging device, high-temperature metallized pellets are obtained, the metallization rate of the high-temperature metallized pellets is 92-95%, the carbon content of the high-temperature metallized pellets is 1-3%, the cold strength of the high-temperature metallized pellets is more than 1500N, the high-temperature metallized pellets are subjected to oxygen-free cooling, then dry grinding and dry separation are carried out, and the iron powder is produced after tailings are removed.
Further, in the step S2, the heat accumulating type heat exchanger is used for drying the material, and the temperature of the flue gas discharged by the heat accumulating type heat exchanger is controlled to be 300-400 ℃.
Further, in the step S4, the heat accumulating type heat exchanger is used for drying the wet pellets, and the hot gas temperature of the heat accumulating type heat exchanger is controlled to be 300-400 ℃.
Furthermore, the flue gas discharged by the rotary hearth furnace is at 900-1000 ℃ and enters a heat accumulating type heat exchanger, and high-temperature hot air at 800-900 ℃ is replaced and introduced into the rotary hearth furnace to be used as combustion air.
Further, the iron powder obtained in the step S7 is used by forming an iron powder cold-pressed block through cold pressing.
Further, the iron powder cold-pressing block can be used for smelting molten steel by a furnace, a blast furnace or a cupola furnace or can be directly used as a product.
Further, the high-volatile coal is lignite or peat with 45-50% of volatile, 43-48% of fixed carbon and less than 10mm of particle size.
Further, the nonferrous smelting slag is copper smelting tailings or nickel smelting tailings.
In the invention: the adhesive adopts bentonite, the main component of which is montmorillonite which is a nonmetallic mineral; the metal aggregating agent adopts high-grade iron ore concentrate with iron grade of more than 62 percent and SiO2The content is 6-8%; the liquid phase modifier is sodium carbonate, is white powder or fine grain crystal, and is a smelting fluxing agent.
The reaction principle of the invention is as follows:
in the invention, high-volatile coal with a certain proportion is added into nonferrous smelting slag, and the high-volatile coal is pyrolyzed at high temperature to produce H2And water gas reaction of carbon to produce H2The chemical reaction equation of its reduction:
C+H2O→CO+ H2
H2reducing Fe in nonferrous smelting slags at high temp2SiO4The chemical reaction equation of its reduction:
Fe2SiO4+2H2→SiO2+2Fe+2H2O
when the pellets are heated in a rotary hearth furnace, the surface temperature of the pellets begins to rise firstly, and when the temperature rises to 350-400 ℃, tar, benzene, naphthalene, alkane, alkene, hydrocarbon and H in the raw coal are reduced on the surface2When the volatile matter is separated out, the volatile matter rises along with the hot air flow and enters a high-temperature combustion space of the furnace hearth for full pyrolysis, and finally the volatile matter is converted into fuel burning out. When the temperature of the surface layer of the pellet is raised to about 900 ℃, the iron oxide on the surface layer reaches the reduction temperature, the coal in the core part of the pellet gradually starts to be pyrolyzed from the shallow layer to the deep layer, tar, benzene, naphthalene, alkane, alkene, hydrocarbon and the like generated by pyrolysis can be fully pyrolyzed when passing through the high-temperature environment of the surface layer or the shallow layer of the pellet, and finally active granular carbon and H are generated2Activated granular carbon is deposited on the surface and shallow layer of the pellet, and H2The iron oxide will penetrate into the pellets and undergo a reduction reaction with the iron oxide reaching the reduction temperature, thereby reducing the iron oxide.
The coal pyrolysis hydrogen reduction process of the pellets in the rotary hearth furnace comprises the following steps: in high-volatile coal such as brown coal, the content of hydrogen element is generally 4-5%, and H is obtained by full pyrolysis of coal2About 70 percent of the total amount of the iron ore acts on the reduction of the iron ore, and the part H2About 40 percent of oxygen elements in iron oxides in the pellets can be removed, and the process is also called as a coal pyrolysis hydrogen reduction process.
The carbon hydrogen gasification reduction process of the pellets in the rotary hearth furnace comprises the following steps: h produced by coal pyrolysis2Reduction of iron oxide to produce H2O，H2The O and newly generated active granular carbon or dead carbon are subjected to carbon gasification reaction to generate H2And CO, H2Reducing iron oxide as reducing agent to obtain H2O will gasify carbon to generate new H2And CO, the repeated circulation generates a violent coupling effect, and H is continuously generated2. Due to H2The reducibility is stronger than that of CO, and according to the selectivity of chemical reaction,only a small part of CO generated in the process participates in the reaction of reducing the iron oxide, most of the CO is discharged into a hearth to be used as fuel, and about 50 percent of oxygen elements of the residual iron oxide in the pellets can be removed through the process, so that the process is called as a carbon hydrogen gasification reduction process.
Carbon reduction process of the pellets in the rotary hearth furnace: when the volatile coal in the pellets is separated out to a certain degree, the iron oxide in the pellets and the stagnant carbon generated by coal pyrolysis are subjected to reduction reaction, and CO is used for the reduction reaction2The reduction rate of the rest iron oxide in the pellets is about 10 percent in the process of gasification agent, and the process is called as carbon reduction process.
The invention changes the traditional direct reduction thought:
in the traditional direct reduction of nonferrous smelting slag, it is widely believed in the industry that in order to reduce the iron silicate in the slag, a certain proportion of limestone is required to be added into the nonferrous smelting slag as a fluxing agent, and because the limestone is decomposed at high temperature to generate CaO, and the CaO is then combined with the iron silicate, FeO in the iron silicate can be dissociated, so that the FeO is conveniently reduced by reducing gas. Under the guidance of the above viewpoint, the nonferrous smelting slag, limestone and reducing coal are ground to a certain granularity, then the materials are proportioned, mixed and pelletized, and the pellets are added into a reducing furnace for high-temperature reduction. The reduction process is characterized in that limestone is added into the pellets and is decomposed at high temperature in the furnace to release CO2，CO2And carrying out carbon gasification reaction with carbon to produce CO, and reducing the iron oxide by using the CO as a reducing agent. Because the concentration of reducing gas CO in the carbon-containing pellets is improved, the reduction speed and the reduction quality of the nonferrous smelting slag are improved, and the chemical reaction formula of the reduction is as follows:
Fe2SiO4(s)+2C(s)→2Fe(s)+SiO2(s)+2CO(g)
in order to promote the reduction reaction of the ferric silicate in the nonferrous smelting slag, limestone is added as a fluxing agent, and the chemical reaction formula is as follows:
Fe2SiO4(s)+2CaO(s)+2C(s)→CaSiO4(s)+2Fe(s)+2CO(g)
according to the research on the direct reduction process of the nonferrous smelting slag, the limestone, the reduction coal, the binder and the conditioning agent are added in the traditional disposal process of the nonferrous smelting slag, and then the limestone is decomposed at high temperature to generate CaO and release the oxygenation agent CO2，CO2Carbon gasification reaction is carried out on the carbon to generate CO, and the CO is used as a reducing agent to reduce the iron oxide. Because the volume ratio of coal to carbon in the pellets is large, CaO and Fe in the copper-nickel slag2SiO4Has a small contact area, and in addition, CaO and Fe in the copper-nickel slag2SiO4The reaction of (2) is a solid-solid reaction, which makes it difficult to continue the reaction. Meanwhile, the method is characterized in that limestone is not added in the direct reduction of the nonferrous smelting slag, and CO is introduced instead2The method of adding the oxygen increasing agent can also achieve the aim of adding limestone into the nonferrous smelting slag to reduce the ferric silicate.
According to the condition, the invention firstly provides Fe in nonferrous smelting slag2SiO4Can be covered with H2Metallurgical mechanism for direct reduction. Due to Fe2SiO4Direct quilt H2The reduction temperature range is generally 900-1000 ℃, no liquid phase is generated on the surface of the nonferrous smelting slag at the temperature, and the effect of directly reducing iron compounds in the nonferrous smelting slag into metallic iron in a solid state can be achieved.
The heating reaction process of the metal oxide in the furnace is as follows:
the inside of the hearth supplies heat through the combustion of the upper burner, and the temperature in the furnace can reach over 1250 ℃. During the rotation of the rotary hearth furnace body, the pellets are successively subjected to the preheating of the loading area, the heating of the heating area, the reduction of the reduction area and the discharging of the discharging area, so that the pellets can be reduced. In the process that flue gas generated in the rotary hearth furnace flows above furnace materials in the reverse direction of the material rotation direction, heat generated by fuel combustion is transferred to roasted pellets by means of radiation heat transfer of the furnace wall and flame, and after carbon-containing pellets are heated to a reduction temperature, metal oxide particles in the pellets react with carbon particles and reducing gas to finally generate metallized pellets with high iron content. When the metallized pellet reaches the discharge port, the metallized pellet after reduction is discharged by a discharging machine. Because the temperature in the rotary hearth furnace is up to 1250-1300 ℃, the retention time of the pellets in the rotary hearth furnace can be adjusted according to the reduction condition of the pellets in the period of one rotation of the rotary hearth furnace bottom, so that the metal oxides in the pellets are almost completely reduced, and carbon not consumed in the reduction is still remained in the sponge iron. Since carbon in the carbon-containing pellets is uniformly distributed in the whole pellets, when the pellets reach a certain temperature, countless carbon particles and reducing gas distributed in the pellets undergo reduction reaction with oxides such as iron, zinc and the like, so that the reduction inside the pellets can be called self-reduction.
Compared with the traditional rotary furnace, the process has the following advantages:
(1) through the coal blending process in the pellet, the nonferrous smelting slag and the high volatile coal are mixed according to a certain proportion, then the pellet is made after the binder with a certain proportion is added, and the pellet is subjected to high-temperature reduction reaction in a rotary hearth furnace to realize the reduction of metal oxides.
(2) The metal oxide has fast high temperature reduction speed in the rotary hearth furnace, many harmful elements and substances in the dust can volatilize or decompose at high temperature, and the combustible can be used as fuel for combustion.
(3) The rotary hearth furnace is a closed system, the micro negative pressure operation is carried out in the furnace, the pollution emission is basically avoided in the production process, the final solid product and the purified flue gas meet the environmental protection requirement, and the waste heat of the flue gas is fully utilized.
(4) In the process of reducing iron-containing materials by the rotary kiln, ring formation easily occurs when the temperature in the rotary kiln is too high, so that the temperature of the rotary kiln is controlled to be 1100-1200 ℃; the process has no ring formation problem in the furnace, the temperature in the furnace can be increased to 1250-1280 ℃, the temperature of the furnace is below the softening point temperature of the material, and the heat transfer temperature difference from flame in the furnace to the material can be increased, so that the productivity and the reduction quality of the rotary hearth furnace are improved.
The invention has the beneficial effects that:
1. the non-ferrous smelting slag is reduced efficiently by adopting a direct reduction process
The invention uses H in the reduction process of nonferrous smelting slag2As a reducing agent. Hydrogen is the most active reducing agent, extracted during the gas-solid reduction of nonferrous smelting slagsHigh gas content of reducing agent H2The proportion can obviously improve the reduction rate and the reduction efficiency of the iron compound. In comparison with the reduction potential of CO, H2The reduction potential of the slag is greatly higher than that of CO, so that Fe in nonferrous smelting slag can be reduced2SiO4And high-efficiency reduction is obtained.
2. Reduction of nonferrous smelting slags with H2Is mainly and easily obtained
The high volatile coal in the pellets is fully pyrolyzed to generate a large amount of H2，H2Formation of gaseous H after reduction of iron oxides2O，H2Gasifying carbon O and generating new H2And CO; due to the selectivity of the chemical reaction, H is used in the whole process of iron oxide reduction2Reduced mainly to H2The method is easy to obtain and use in production, and realizes the thermal intersection of the coal full pyrolysis and the iron oxide reduction process.
3. The direct reduction of the nonferrous smelting slag has high heat transfer efficiency, high reduction speed and high productivity
The reaction temperature point of hydrogen metallurgy is low, and more heat can be transferred into the material layer at the same hearth temperature, so that the reduction speed of the pellets is accelerated, the process energy consumption is reduced, and the productivity can be greatly improved on the premise of the same heat transfer quantity.
4. Reduction of CO2Discharging
The invention adopts a coal-based direct reduction process for nonferrous smelting slag, the reducing agent uses high-volatile coal, the fixed carbon content is low, the hydrogen element content is high, and H is used in the metallurgical reduction process2Mainly CO in the discharged flue gas2The content is greatly reduced compared with the traditional 'iron burning' process.
Drawings
FIG. 1 is a process diagram of the present invention.
Detailed Description
The main equipment used in the process comprises: the dry-type coal mill, the dry-type ore mill, the proportioning machine, the mixing machine, the pelletizer, the wet-bulb dryer, the nonferrous slag dryer, the coal dryer, the hydrometallurgy rotary hearth furnace, the regenerative heat exchanger, the blower, the anaerobic cooling device, the dry mill dry separator, the iron powder cold press, the electric furnace, the blast furnace or the cupola furnace, the dust removal system and the smoke extractor.The core of the process is that after nonferrous smelting slag and coal are ground in a dry mode, a binder, a focusing agent and a liquid-phase modifying agent are mixed according to a certain weight proportion, then the mixture is mixed uniformly and pelletized, and H generated by full pyrolysis of the coal is utilized in the process of heating pellets in a rotary hearth furnace and raising the temperature2And H2H is generated by carbon gasification reaction with O as gasification agent2Reducing the iron ore, and controlling the temperature of a hearth to 1250-1280 ℃ and the roasting time to be 28-35 min to fully reduce the nonferrous smelting slag.
The invention is further illustrated by the following specific examples:
example 1:
a process for producing a metallized furnace material by directly reducing nonferrous smelting slag comprises the following steps:
s1 raw materials are selected as follows: the raw materials are 38-44% in grade and SiO230-40% of copper smelting slag with the granularity of less than 10mm, wherein the fuel and the reducing agent adopt high-volatility coal such as lignite with the volatile content of 45-50%, the fixed carbon content of 43-48% and the granularity of less than 10 mm;
and (S2) drying the material: respectively adding copper smelting slag and lignite with high water content into a non-ferrous slag dryer and a coal dryer, and respectively drying the materials by adopting flue gas discharged by a heat accumulating type heat exchanger and with the temperature of 300-400 ℃ as a drying heat source to remove water carried in the materials;
s3 grinding the materials: grinding the copper smelting slag to be below 300 meshes and accounting for more than 85% by using a dry coal mill, and grinding the lignite to be below 200 meshes and accounting for more than 80% by using a dry ore mill;
preparation of S4 carbon-containing pellets: selecting 100 parts of copper smelting slag, 20 parts of lignite, 3 parts of binder, 13 parts of focusing agent and 2 parts of liquid-phase modifying agent according to parts by weight, blending and uniformly mixing, and adding water to prepare wet pellets with the particle size of 15 mm;
paving the wet pellets on a wet pellet dryer material bed, drying by using flue gas discharged from a heat accumulating type heat exchanger and having the temperature of 300-400 ℃ as a heat source, purifying the flue gas discharged after the materials are dried and having the temperature of 150-180 ℃ by using a dust removal system, and then pressurizing and discharging by using a smoke extractor;
s5 rotary hearth furnace burden distribution: conveying the dried pellets to a feeding end of a rotary hearth furnace, uniformly paving the pellets on the bottom of the rotary hearth furnace by using a distributor, and controlling the paving thickness to be 50-70 mm;
s6 roasting: controlling the temperature of a hearth to 1250-1260 ℃, and the roasting time to be 28-31 min, so that the copper smelting slag is reduced in the furnace;
s7 discharging: the pellets reach a discharging area of the rotary hearth furnace, and are continuously discharged through a spiral discharging device to obtain high-temperature metallized pellets, wherein the metallization rate of the high-temperature metallized pellets is 92-95%, the carbon content of the high-temperature metallized pellets is 1-3%, and the cold strength of the high-temperature metallized pellets is more than 1500N; and (3) after anaerobic cooling, sending the iron powder to a dry grinding and dry separation machine, removing tailings to produce iron powder, and performing cold pressing on the obtained iron powder to form an iron powder cold-pressed block, wherein the iron powder cold-pressed block can be used for smelting molten steel by a furnace, a blast furnace or a cupola, or can be directly used as a product.
Example 2:
a process for producing a metallized furnace material by directly reducing nonferrous smelting slag comprises the following steps:
s1 raw materials are selected as follows: the raw materials are 38-44% in grade and SiO2The content of the nickel smelting slag is 30-40%, the granularity of the nickel smelting slag is less than 10mm, and the fuel and the reducing agent adopt high-volatility coal such as lignite, wherein the high-volatility coal comprises 45-50% of volatile components, 43-48% of fixed carbon and the granularity of the coal is less than 10 mm;
and (S2) drying the material: adding nickel smelting slag and lignite with high water content into a non-ferrous slag dryer and a coal dryer respectively, and drying the materials respectively by using flue gas discharged by a heat accumulating type heat exchanger and with the temperature of 300-400 ℃ as a drying heat source to remove water carried in the materials;
s3 grinding the materials: the nickel smelting slag is ground to below 300 meshes by a dry coal mill and accounts for more than 85%, and the lignite is ground to below 200 meshes by a dry ore mill and accounts for more than 80%;
preparation of S4 carbon-containing pellets: selecting 100 parts of nickel smelting slag, 28 parts of lignite, 1 part of binder, 9 parts of focusing agent and 1 part of liquid-phase modifying agent according to parts by weight, blending and uniformly mixing, and adding water to prepare wet pellets with the particle size of 20 mm;
paving the wet pellets on a wet pellet dryer material bed, drying by using flue gas discharged from a heat accumulating type heat exchanger and having the temperature of 300-400 ℃ as a heat source, purifying the flue gas discharged after the materials are dried and having the temperature of 150-180 ℃ by using a dust removal system, and then pressurizing and discharging by using a smoke extractor;
s5 rotary hearth furnace burden distribution: conveying the dried pellets to a feeding end of a rotary hearth furnace, uniformly paving the pellets on the bottom of the rotary hearth furnace by using a distributor, and controlling the paving thickness to be 50-70 mm;
s6 roasting: controlling the temperature of the hearth to 1270-1280 ℃ and the roasting time to be 30-33 min, so that the nickel smelting slag is reduced in the furnace;
s7 discharging: the pellets reach a discharging area of the rotary hearth furnace, and are continuously discharged through a spiral discharging device to obtain high-temperature metallized pellets, wherein the metallization rate of the high-temperature metallized pellets is 92-95%, the carbon content of the high-temperature metallized pellets is 1-3%, and the cold strength of the high-temperature metallized pellets is more than 1500N; and (3) after anaerobic cooling, sending the iron powder to a dry grinding and dry separation machine, removing tailings to produce iron powder, and performing cold pressing on the obtained iron powder to form an iron powder cold-pressed block, wherein the iron powder cold-pressed block can be used for smelting molten steel by a furnace, a blast furnace or a cupola, or can be directly used as a product.
Example 3:
a process for producing a metallized furnace material by directly reducing nonferrous smelting slag comprises the following steps:
s1 raw materials are selected as follows: the raw materials are 38-44% in grade and SiO2The content of the nonferrous smelting slag is 30-40%, the granularity is less than 10mm, and the fuel and the reducing agent adopt high-volatility coal such as lignite, the volatility of which is 45-50%, the fixed carbon content of which is 43-48% and the granularity is less than 10 mm;
and (S2) drying the material: respectively adding copper smelting slag and lignite with high water content into a non-ferrous slag dryer and a coal dryer, and respectively drying the materials by adopting flue gas discharged by a heat accumulating type heat exchanger and with the temperature of 300-400 ℃ as a drying heat source to remove water carried in the materials;
s3 grinding the materials: the copper smelting slag is ground to be below 300 meshes and account for more than 85% by using a dry coal mill, and the lignite is ground to be below 200 meshes and account for more than 80% by using a dry ore mill;
preparation of S4 carbon-containing pellets: selecting 100 parts of copper smelting slag, 24 parts of lignite, 5 parts of binder, 5 parts of focusing agent and 2 parts of liquid-phase modifying agent according to parts by weight, blending and uniformly mixing, and adding water to prepare wet pellets with the particle size of 25 mm;
paving the wet pellets on a wet pellet dryer material bed, drying by using flue gas discharged from a heat accumulating type heat exchanger and having the temperature of 300-400 ℃ as a heat source, purifying the flue gas discharged after the materials are dried and having the temperature of 150-180 ℃ by using a dust removal system, and then pressurizing and discharging by using a smoke extractor;
s5 rotary hearth furnace burden distribution: conveying the dried pellets to a feeding end of a rotary hearth furnace, uniformly paving the pellets on the bottom of the rotary hearth furnace by using a distributor, and controlling the paving thickness to be 50-70 mm;
s6 roasting: controlling the temperature of the hearth to 1260-1270 ℃ and the roasting time to be 32-35 min, so that the copper smelting slag is reduced in the furnace;
s7 discharging: the pellets reach a discharging area of the rotary hearth furnace, and are continuously discharged through a spiral discharging device to obtain high-temperature metallized pellets, wherein the metallization rate of the high-temperature metallized pellets is 92-95%, the carbon content of the high-temperature metallized pellets is 1-3%, and the cold strength of the high-temperature metallized pellets is more than 1500N; and (3) after anaerobic cooling, sending the iron powder to a dry grinding and dry separation machine, removing tailings to produce iron powder, and performing cold pressing on the obtained iron powder to form an iron powder cold-pressed block, wherein the iron powder cold-pressed block can be used for smelting molten steel by a furnace, a blast furnace or a cupola, or can be directly used as a product.
After the pellets are heated, expanded and pulverized, the heat transfer efficiency is reduced, the metal reduction reaction speed is reduced, the reaction time is prolonged, and the reaction energy consumption is increased. In order to prevent the carbon-containing pellets from generating expansion and pulverization in the reduction process, the process mixes the liquid-phase conditioning agent with a proper proportion into the pellets, so that the pellets have proper liquid-phase quantity in the high-temperature reduction process, and the aim of reasonably matching the liquid-phase quantity and the gas-phase quantity in the pellets is fulfilled, thereby effectively controlling the expansion and pulverization degree of the pellets and simultaneously improving the strength of the metallized pellets.
The nonferrous smelting slag is reduced and established on the basis of hydrogen metallurgy, heat is recycled through the heat accumulating type heat exchanger, and the productivity can be greatly improved on the premise of the same heat transfer quantity. More importantly, the reaction temperature point of hydrogen metallurgy is low, iron oxide is reduced at a lower temperature, and the temperature is further reduced when active granular carbon participates in the reaction; because the heat transfer quantity depends on the difference between the temperature of the hearth and the temperature of the material, more heat can be transferred into the material layer under the same temperature of the hearth, and the use efficiency of the heat is improved.
The project realizes the high integration of the full pyrolysis process of coal and the metallurgical reduction process of nonferrous smelting slag in a thermal state, and the whole iron making process only adopts volatile coal without using coke. The reduction of iron oxides is converted from the traditional metallurgical coke-based carbon metallurgy process to "H" iron2And + active granular carbon' as the main hydrogen metallurgy process, so as to achieve the purposes of energy conservation and emission reduction of the iron making process.
Because the iron silicate phase structure in the nonferrous smelting slag is compact, in the reduction process of the iron silicate, reducing gas is difficult to diffuse into copper-nickel smelting slag particles, and meanwhile, gas generated after reduction stays in the particles and is difficult to diffuse out, so that the reduction speed of the nonferrous smelting slag is increased, and the metallization rate after reduction is improved, the nonferrous smelting slag is required to be ground to 0-300 meshes and accounts for more than 85%.
It should be noted that the above are only some embodiments of the present invention, and it should be noted that, for those skilled in the art, many modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.
Claims (8)
1. A process for producing a metallization furnace material by directly reducing nonferrous smelting slag is characterized by comprising the following steps:
s1 raw materials are selected as follows: the raw materials are 38-44% in grade and SiO2The content of the nonferrous smelting slag is 30-40%, the granularity is less than 10mm, and the fuel and the reducing agent adopt high-volatile coal;
and (S2) drying the material: respectively drying the nonferrous smelting slag and the high-volatile coal to remove water carried in the materials;
s3 grinding the materials: grinding the nonferrous smelting slag to below 300 meshes and accounting for more than 85 percent, and grinding the high-volatile coal to below 200 meshes and accounting for more than 80 percent;
preparation of S4 carbon-containing pellets: selecting 100 parts of colored smelting slag, 20-28 parts of high-volatile coal, 1-5 parts of binder, 5-13 parts of focusing agent and 1-2 parts of liquid-phase modifying agent according to parts by weight, mixing uniformly, adding water to prepare wet pellets with the particle size of 15-25 mm, and drying the wet pellets;
s5 rotary hearth furnace burden distribution: paving the dried pellets to the bottom of a rotary hearth furnace, wherein the paving thickness is 50-70 mm;
s6 roasting: controlling the temperature of a hearth to 1250-1280 ℃ and the roasting time to be 28-35 min, so that the nonferrous smelting slag is reduced in the furnace;
s7 discharging: the pellets reach a discharging area of the rotary hearth furnace, are continuously discharged through a discharging device, high-temperature metallized pellets are obtained, the metallization rate of the high-temperature metallized pellets is 92-95%, the carbon content of the high-temperature metallized pellets is 1-3%, the cold strength of the high-temperature metallized pellets is more than 1500N, the high-temperature metallized pellets are subjected to oxygen-free cooling, then dry grinding and dry separation are carried out, and the iron powder is produced after tailings are removed.
2. The process for producing the metallized furnace material by directly reducing the nonferrous smelting slag according to the claim 1, wherein the heat accumulating type heat exchanger is used for drying the material in the step S2, and the temperature of the flue gas discharged by the heat accumulating type heat exchanger is controlled to be 300-400 ℃.
3. The process for producing a metallized furnace material by directly reducing nonferrous smelting slag according to claim 2, wherein in the step S4, a regenerative heat exchanger is used for drying the wet pellets, and the temperature of hot gas of the regenerative heat exchanger is controlled to be 300-400 ℃.
4. The process for producing the metallized furnace material by directly reducing the nonferrous smelting slag according to the claim 2, wherein the flue gas at the temperature of 900-1000 ℃ discharged by the rotary hearth furnace enters a regenerative heat exchanger, and the high-temperature hot air at the temperature of 800-900 ℃ is replaced and introduced into the rotary hearth furnace to be used as combustion air.
5. The process for the direct reduction of nonferrous smelting slag to produce metallized furnace burden according to claim 1, wherein said iron powder obtained in step S7 is cold pressed to form an iron powder cold pressed block for use.
6. The process for producing a metallized furnace charge by direct reduction of nonferrous smelting slag according to claim 5, wherein said iron powder cold-pressed block can be used for smelting molten steel in electric furnaces, blast furnaces or cupola furnaces, or can be used directly as a product.
7. The process for producing a metallized furnace material by directly reducing nonferrous smelting slag according to claim 1, wherein the high-volatile coal is lignite or peat with 45-50% of volatile matter, 43-48% of fixed carbon content and 10mm or less of particle size.
8. The process for producing the metallized furnace material by directly reducing the nonferrous smelting slag according to any one of claims 1 to 7, wherein the nonferrous smelting slag is copper smelting tailings or nickel smelting tailings.
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| CN113955757A (en) * | 2021-11-26 | 2022-01-21 | 内蒙古禹源机械有限公司 | Device and process for preparing carbon dioxide capture agent and co-producing hydrogen and alloy from carbon and gasified slag |
| CN114395697A (en) * | 2022-01-04 | 2022-04-26 | 中冶南方工程技术有限公司 | Method for reducing carbon emission in reduction dezincification process |
| CN114774685A (en) * | 2022-04-24 | 2022-07-22 | 酒泉钢铁(集团)有限责任公司 | Method for treating limonite type laterite-nickel ore hydrometallurgy slag |
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