Method and device for smelting nonferrous metallurgical slag

Abstract

The invention relates to a smelting method of nonferrous metallurgical slag, which is characterized by comprising the following steps of: adding the slag into a molten pool smelting furnace, and immersing a reducing agent and a fluxing agent into the slag; and current is introduced into the slag, the temperature of the slag is controlled to be the smelting temperature of 1450-1800 DEG C through resistance heating of the slag, and the iron oxide reduction and slagging technological process is completed. According to the smelting method, the recovery rate of iron is close to 100%. The final slag has higher use value than the original slag, only the minimum amount of low-temperature high-purity CO furnace gas is discharged, and the environmental benefit and the economic benefit are particularly obvious.

Description

Technical Field

[0001] The invention relates to a smelting method and an ironmaking device for nonferrous metallurgical slag. Background Art

[0002] In the prior art, the side-blown furnace slag and the fuming furnace slag from the post-treatment of non-ferrous metallurgical slags such as copper, lead, zinc, and tin contain about 30% Fe and other valuable metals Pb and Zn, which have high energy and high utilization value. The prior art processes all use molten waste slag to quench it into solid waste slag with water and use it as an iron-containing auxiliary material for building material manufacturers, which is a waste of resources and energy. Summary of the invention

[0003] The purpose of the present invention is to solve the problems in the prior art and provide a smelting method for nonferrous metallurgical slag capable of recovering iron.

[0004] In order to achieve the above objectives, the present invention is implemented by the following technical solutions:

[0005] The smelting method of non-ferrous metallurgical slag is characterized in that the slag is added into a molten pool smelting furnace, and a reducing agent and a flux are immersed in the slag; an electric current is passed through the slag, and the temperature of the slag is controlled at a smelting temperature of 1450°C to 1800°C by using the resistance heating of the slag to complete the iron oxide reduction and slag making process.

[0006] According to one embodiment of the present invention, the slag exists in the molten pool smelting furnace in the form of a melt; the reducing agent and the flux are solid block materials, the reducing agent and the flux are added from above the slag, and accumulate in the furnace to form a solid material column, and the solid material column is partially immersed in the melt under the action of its own weight and / or mechanical pressure.

[0007] According to one embodiment of the present invention, before the reducing agent and the flux come into contact with the slag, the reducing agent and the flux are preheated using high-temperature furnace gas generated during the smelting process in the molten pool smelting furnace.

[0008] According to one embodiment of the present invention, the reducing agent includes coke, or a mixture of coke and coal.

[0009] According to one embodiment of the present invention, the flux comprises quicklime, fluorite and / or caustic soda.

[0010] According to one embodiment of the present invention, the slag is liquid iron-containing slag.

[0011] According to one embodiment of the present invention, the electric heating is direct current heating; a top graphite electrode is provided on the top of the molten pool smelting furnace, and a graphite bottom electrode is provided on the bottom; the top graphite electrode is inserted from the top of the furnace down to a selected depth of the slag; the graphite bottom electrode is inserted from the bottom of the furnace and connected to the dead iron layer area at the bottom of the furnace, and the bottom graphite electrode and the dead iron layer at the bottom of the furnace together constitute the bottom electrode.

[0012] According to one embodiment of the present invention, the space in the molten pool smelting furnace can be divided into a molten pool and a furnace. The molten pool is divided into a dead iron layer area, an iron-changing layer area, a precipitation area and a reaction area from bottom to top; the dead iron layer area is a stable molten iron layer, and the iron-changing layer area is a molten iron layer formed in the furnace by liquid molten iron generated after slag reduction in an iron discharge cycle; the precipitation area is liquid slag, which is a mixing area of ​​original slag and final slag; the reaction area is a mixing area of ​​liquid slag, solid reducing agent and flux; the furnace is a solid material column area from the liquid level of the reaction zone to the top of the furnace, and the empty furnace area is from the top of the solid material column to the top of the furnace.

[0013] According to one embodiment of the present invention, the molten pool smelting furnace has a material discharge flue at the top, a slag input port at the bottom, a molten iron discharge port at the bottom, and a molten final slag discharge port at the top.

[0014] According to one embodiment of the present invention, the solid reducing agent and flux move from top to bottom, and the molten slag moves in countercurrent from bottom to top, so that the molten iron-containing slag contacts the solid reducing agent and flux.

[0015] According to one embodiment of the present invention, it also includes a pre-furnace, which is placed on one side of the molten pool furnace and connected to the molten pool smelting furnace. Before the raw slag enters the molten pool smelting furnace, the pre-furnace is used to heat and keep the raw slag warm.

[0016] According to one embodiment of the present invention, a pressure pusher is provided on the top of the molten pool smelting furnace, and the pressure pusher can be reciprocated and lifted; during the reciprocating lifting process of the pressure pusher, the reducing agent and the flux are pressed into the slag to a selected depth.

[0017] Another object of the present invention is to provide an ironmaking apparatus for non-ferrous metallurgical slag capable of recovering iron in the slag.

[0018] The ironmaking device for non-ferrous metallurgical slag is characterized in that it includes a molten pool smelting furnace, which is provided with a top graphite electrode and a graphite bottom electrode; the top graphite electrode can be raised and lowered; the molten pool smelting furnace is provided with a slag input port, a molten iron discharge port, a final slag discharge port and a discharge flue; the discharge flue is arranged at the upper part of the molten pool smelting furnace; a material pressing pusher is arranged on the top of the molten pool smelting furnace, and the material pressing pusher can be reciprocated and raised and lowered.

[0019] According to one embodiment of the present invention, a power source is further included, and the power source is used to supply power so that the top graphite electrode, the graphite bottom electrode, and the slag in the furnace form a current loop.

[0020] According to one embodiment of the present invention, the power supply is a direct current power supply, or the power supply is an alternating current power supply and further comprises a rectifier transformer, and the alternating current is inverted into direct current through the rectifier transformer.

[0021] According to one embodiment of the present invention, it further comprises a pre-furnace, wherein the pre-furnace is used for heating and / or keeping the slag warm; the pre-furnace is connected to the molten pool smelting furnace.

[0022] According to one embodiment of the present invention, the pre-furnace is an electric heating furnace.

[0023] According to one embodiment of the present invention, the slag inlet is located lower than the final slag tapping port and higher than the molten iron tapping port.

[0024] The inventors found through research that:

[0025] 1. The iron in the slag exists in the form of FeO. During the smelting process of FeO, the reduction reaction of FeO can be decomposed into:

[0026]

[0027] According to the above reaction formula, the reducing agent of FeO is CO, and the reduction reaction produces CO2 gas. When the temperature of CO2 gas reaches 900℃ under the condition of C, the reduction reaction of CO2 occurs. 1 mol of CO2 reacts to generate 2 mol of CO, which is a gasification reaction. 1 mol of CO is used for the reduction reaction of FeO, and the other 1 mol of CO gas is discharged. According to the above theoretical reaction equation, enough CO can be generated, indicating that the reduction reaction of FeO does not lack CO reducing agent. However, in the actual smelting process, any injection will reduce the reducing atmosphere, resulting in a decrease in the recovery rate of iron.

[0028] According to the reaction formula, the reaction of CO2+C=2CO is an endothermic reaction. Therefore, the reduction reaction of FeO, the reduction reaction of CO2 and C, and the heat supply must be carried out simultaneously at the same time and place. The most important thing is to provide enough heat to the system in time. Because the two reactions are in a high-carbon environment, the reaction temperature is about 900℃, and the melting point of the iron-containing slag increases significantly after the iron is reduced. If enough heat is not provided in time, a freezing cylinder accident will occur. Similarly, the reduction reaction of CO2 and C absorbs a lot of heat. To ensure the smelting temperature of 1500℃, enough heat must also be provided in time. If enough heat cannot be provided, the reduction reaction of the slag cannot continue.

[0029] The bulk specific gravity of the reducing agent and the flux is relatively small, which is less than the specific gravity of the slag. They naturally float above the liquid surface of the slag. If sufficient external force is not applied to immerse them in the molten pool, they cannot contact the iron-containing slag, which will inevitably cause the reduction reaction to be ineffective. In order to make carbon available for the reaction, the present invention relies on the dead weight of the solid material column and / or mechanical operation to partially immerse the solid material column into the slag in the reaction zone, so that the reducing agent and the flux are fully in contact with the slag to provide carbon for the reduction reaction.

[0030] Since the specific gravity of molten slag is the highest, followed by final slag, and solid materials such as flux and reducing agent have the lowest specific gravity, the molten slag is input from the bottom and solid materials are added from the top. The two flow in reverse, which greatly increases the contact opportunity of the reaction materials. The molten iron is discharged from the bottom of the furnace, and the final slag after reduction is discharged from the top of the reaction zone.

[0031] The electric heating system of this molten pool smelting furnace does not generate arcs. Otherwise, under the condition of arc discharge, the melt will be heated to an extremely high temperature, and under the condition of strong reducing atmosphere, the extremely high temperature will cause a large amount of silicon to be reduced, causing the silicon content of pig iron to exceed the standard. This molten pool smelting furnace adopts resistance heating and is a resistance molten pool smelting furnace.

[0032] The invention has low investment, simple and reliable operation, and the iron recovery rate is close to 100%. The final slag has higher use value than the original slag, and only emits at least two times of low-temperature high-concentration CO furnace gas, and the environmental and economic benefits are particularly obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structure of the smelting device for nonferrous metallurgical slag in the present invention.

[0034] Figure 2 The figure is a flow chart of the smelting method of nonferrous metallurgical slag in the present invention. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below through specific examples.

[0036] like Figure 1As shown, one of the ironmaking devices for nonferrous metallurgical slag used in the present invention includes a molten pool smelting furnace 1 and a pre-furnace 2. The molten pool smelting furnace 1 is provided with a top graphite electrode 3 and a graphite bottom electrode 4. The top graphite electrode 3 is used as a negative electrode, and the graphite bottom electrode 4 is used as a positive electrode. The top graphite electrode 3 can be raised and lowered. The lifting and lowering of the top graphite electrode 3 can be driven by a motor or a hydraulic cylinder. According to specific structural requirements, corresponding transmission devices such as gears, chains or transmission belts can also be provided. The molten pool smelting furnace 1 is provided with a slag input port 13, a molten iron discharge port 14 and a final slag discharge port 15. The slag input port 13 is located lower than the final slag discharge port 15 and higher than the molten iron discharge port 14. A material discharge flue 16 is provided on the upper part of the molten pool smelting furnace 1. The material discharge flue 16 is used to discharge two solid materials, flux and reducing agent, and furnace gas. A material pressing pusher 17 is provided on the top of the molten pool smelting furnace 1. The material pressing pusher 17 is reciprocatingly raised and lowered. The pressure pusher 17 is used to apply mechanical thrust to the solid material, so that the flux and the reducing agent move downward, so that the solid material is partially immersed in the slag. The pressure pusher 17 can adopt various suitable shapes, as long as you can push down the solid material column. In this embodiment, the pressure pusher 17 is cylindrical. The reciprocating lifting of the pressure pusher 17 can be driven by a motor or a hydraulic cylinder, and a transmission device such as a gear, a chain or a transmission belt can be configured according to actual needs. The number of pressure pushers 17 can be set to multiple, and they are arranged around the top graphite electrode 3. In this embodiment, the number of pressure pushers 17 is four, which are arranged around the top graphite electrode 3.

[0037] The present invention further comprises a DC power supply (not shown in the figure), which is used to supply power so that the top graphite electrode 3, the bottom graphite electrode 4, the slag or the melt form a current loop. The power supply is a DC power supply.

[0038] A positive electrode 5 and a negative electrode 6 are provided in the pre-furnace 2 for heating and heat preservation of the raw slag so as to keep the slag in a molten and flowable state. The pre-furnace 2 is an electric heating furnace that uses electric current to heat the slag. The pre-furnace 2 is connected to the molten pool smelting furnace 1 through the slag input port 13. The raw slag in the pre-furnace 2 is transported to the molten pool smelting furnace 1 through the slag input port 13.

[0039] The smelting method of nonferrous metallurgical slag of the present invention is as follows: Figure 2 The process flow shown is to use Figure 1 Taking the ironmaking device of nonferrous metallurgical slag shown in the figure as an example, the method comprises:

[0040] The smelting method of nonferrous metallurgical slag is to keep the liquid slag at a high temperature of 1300°C to 1350°C in the pre-furnace 2 by electric heating, so that the slag is in a flowable state, and ensure that the slag can be continuously transported to the molten pool smelting furnace 1 through the slag input port 13. The liquid slag and the graphite bottom electrode 4 and the top graphite electrode 3 form a circuit loop. The current is transported to the slag through the graphite bottom electrode 4 and the top graphite electrode 3, and the resistance of the slag is used to generate heat.

[0041] The reducing agent and flux are added into the molten pool smelting furnace 1 from the discharge flue 16 at the upper part of the molten pool smelting furnace 1, and naturally accumulate in the furnace to form a solid material column. The solid material is preheated to a high temperature in the furnace using high temperature furnace gas.

[0042] When smelting first begins, the steps are as follows:

[0043] 1. Insert the top graphite electrode 3 into the molten pool smelting furnace 1 so that the end of the top graphite electrode 3 is close to the furnace bottom.

[0044] 2. Add reducing agent and flux into the molten pool smelting furnace 1 from the unloading flue 16 until the reducing agent and flux reach a predetermined height. The predetermined height can be determined according to actual needs, the amount of reducing agent and flux can be determined according to the amount of slag entering, and the amount of reducing agent and flux added can also be excessive. This is a prior art and will not be repeated here. The reducing agent includes coke, or a mixture of coke and coal. If a mixture of coke and coal is used, the weight ratio of coke is greater than 50%, for example, the weight ratio of coke is 60%, 75%, 95%, etc. This embodiment is illustrated by the reducing agent being coke. The coke is in a solid block, and the block diameter is preferably 30 to 40 mm. The flux includes quicklime, fluorite and / or caustic soda. This example takes the flux as block quicklime as an example. Quicklime is in a solid block, and the block diameter is preferably 30 to 40 mm. The amount of reducing agent added is equal to the amount consumed by the reduction reaction in the furnace. Quicklime is used to assist fluxing, which has the same function as that used in existing metallurgy, and the amount added can be determined based on the designed pH value of the slag.

[0045] 3. The top graphite electrode 3 and the bottom graphite electrode 4 are energized to form an arc, which heats the molten pool smelting furnace 1, so that the temperature of the reducing agent and the flux rises to above 1500°C.

[0046] 4. Breaded iron is put into the molten pool smelting furnace 1. The breaded iron is melted at high temperature and sinks to the bottom of the furnace, and part of it forms a dead iron layer area 7. The dead iron layer area 7 contacts the graphite bottom electrode 4 to form a positive electrode.

[0047] 5. The raw slag is kept in a molten and flowable state in the pre-furnace 2. The raw slag in the pre-furnace 2 continuously enters the molten pool smelting furnace 1 from the slag input port 13 according to the designed processing capacity. The raw slag contacts the reducing agent and flux, and starts the reduction reaction and slag-making process in a high-temperature and high-carbon environment. As the raw slag is continuously added, the liquid level in the molten pool smelting furnace 1 continues to rise, and the top graphite electrode 3 is lifted accordingly and maintains a certain gap with the slag liquid level. Before the top graphite electrode 3 contacts the slag, the slag is mainly heated by electric arc to provide the heat required for the reduction reaction. Until finally, as the liquid level rises, when the liquid level reaches the designed height, the end of the top graphite electrode 3 is inserted to the designed depth below the liquid level, and the arc heating is converted to resistance heating. At this point, the furnace opening process is completed. The depth of the top graphite electrode 3 inserted into the liquid surface is aimed at ensuring that the slag can be smoothly heated by electric current, and its specific depth can be determined according to actual conditions.

[0048] As smelting progresses, the smelting enters a continuous and normal smelting process:

[0049] 1. The smelting process in the molten pool smelting furnace 1 forms the following functional zones: from bottom to top, there are dead iron layer zone 7, iron-changing layer zone 8, precipitation zone 9, reaction zone 10, solid material column zone 11 and empty furnace zone 12. The height of each functional zone is determined according to material consumption and output. The molten iron at the bottom and the graphite bottom electrode 4 form a positive electrode. The dead iron layer is the molten iron layer below the tapping port 14, and the height of the tapping port is required to be greater than or equal to 100; the iron-changing layer zone 8 is mainly molten iron generated after the slag is reduced in an iron-discharging cycle. The molten iron outlet 14 is set in this area to discharge the generated molten iron. The precipitation zone 9 is mainly slag. The reduced iron is liquid particles, which form droplets after collision. Under the action of gravity, they pass through the precipitation zone 9 and sink to the bottom of the furnace. The slag input port 13 is set at the upper position of the precipitation zone 9. The reaction zone 10 is a solid-liquid mixed zone of molten slag, reducing agent and solvent. The original slag passes through the reaction zone from bottom to top, FeO is continuously reduced, the concentration of FeO decreases, and finally it is completely reduced, and the original slag becomes final slag.

[0050] 2. Before the raw slag is fed into the molten pool smelting furnace 1, it must be heated to above 1300°C to maintain the necessary fluidity of the slag. The amount of raw slag added must be balanced in basic flow and cannot be interrupted.

[0051] 3. The iron can be tapped continuously or intermittently, and continuous tapping is preferred.

[0052] 4. The slag can be discharged continuously or intermittently, preferably continuously.

[0053] 5. The furnace gas generated in the reaction zone passes through the solid material column area 11, heats the reducing agent and the co-solvent in the solid material column area 11, and then enters the furnace 12 and is discharged from the unloading flue 16.

[0054] 6. Solid materials are added into the molten pool smelting furnace 1 from multiple discharge flues 16 respectively.

[0055] 7. The reducing agent and the solvent are partially pressed into the reaction zone 10 below the liquid surface by utilizing their own weight and the material pusher 17 in the solid material column area 11, so that the reducing agent and the solvent are in contact with the slag to provide the reducing agent for FeO reduction.

[0056] The working conditions in the furnace are:

[0057] 1. Melting reduction ironmaking requires a reducing atmosphere with a molar ratio of (CO+H2) / (CO+CO2+N2+H2O) greater than or equal to 85%. This process uses electric heating and does not require gas injection into the molten pool smelting furnace. The reducing atmosphere has a CO concentration of nearly 100%, which is very easy to achieve the reducing atmosphere requirements.

[0058] 2. The melting temperature is controlled between 1450℃ and 1800℃.

[0059] 3. This process adopts negative pressure operation, and the negative pressure value is controlled at -30 to -80Pa, which can prevent the leakage of furnace gas. Maintaining it at negative pressure is conducive to meeting environmental protection requirements. However, the smelting method of the present invention does not have to be carried out under negative pressure.

[0060] In the present invention, the precipitation zone 9 is a carbon-free slag with a large specific resistance, which is a high-temperature zone in the furnace. The raw slag enters the furnace and is quickly heated to a high temperature. The slag enters from the bottom of the furnace, and as the slag is continuously added and flows upward, it contacts with the descending solid material reducing agent and combustion-supporting agent, and a reduction reaction occurs. The molten iron produced by the reduction reaction has a large specific gravity, and the molten iron passes through the precipitation zone 9 to reach the iron-changing layer zone 8. In order to protect the furnace bottom, a dead iron layer zone 7 is provided at the bottom of the furnace cylinder. The final slag generated by the reduction reaction has a smaller specific gravity than the raw slag, and the raw slag is continuously added, so the final slag flows upward, passes through the reaction zone 10, and is discharged from the final slag discharge port 15 at the top of the reaction zone 10. The high-temperature furnace gas generated during smelting passes upward through the reaction zone 10, the solid material column 11, and the empty furnace 12, and is discharged from the solid material discharge flue 16.

[0061] The raw slag input port 13 is located in the precipitation zone 9, which is mainly the mutual melting zone of raw slag and final slag. The raw slag enters from this zone and mixes with the melt staying in the precipitation zone 9. It is actually a mixed melt zone of raw slag and final slag, which is the raw material zone. The mixed melt in the precipitation zone 9 does not contain carbon and has a relatively large relative resistivity. It is the main heating zone of electric heating. The FeO-containing slag to be reduced is heated to 1600℃~1800℃ here. The precipitation zone 9 is also a buffer zone for the insertion of the top graphite electrode 3. Without this sufficient buffer zone, the insertion of the top graphite electrode 3 is impossible.

[0062] Above the precipitation zone 9, a solid-liquid mixed zone is formed by slag, solid block reducing agent and combustion aid, which is the reaction zone 10. The main substances are slag, reducing agent and flux. This zone is a secondary hot zone. Because the mixed melt in the reaction zone contains a large amount of coke, the specific resistance is small and the calorific value is low. The reduction reaction of FeO mainly occurs at the bottom of the reaction zone 10, that is, at the junction with the precipitation zone 9. FeO that is not completely reduced is completely reduced in the reaction zone 10 in the countercurrent upward direction.

[0063] Above the reaction zone 10 is a solid material column zone 11 formed by the reducing agent and the flux. In this zone, the solid material is preheated by the physical heat of the CO furnace gas generated by the reduction reaction. This is the most efficient waste heat utilization method, which can reduce the exhaust temperature of the furnace gas to about 200°C. At the same time, when the solid material descends to the surface of the molten pool, it can reach about 1400°C.

[0064] During the smelting process, since the bulk specific gravity of the solid material is relatively small, a material pusher 17 must be used to apply mechanical thrust to the material column so that part of the material column is immersed in the slag in the reaction zone 10 .

[0065] In the present invention, the temperature of the original slag is between 1250°C and 1300°C, carrying physical heat; the slag is liquid, and as a metallurgical charge, it no longer needs to consume phase change heat; Fe exists in the form of 2FeO.SiO2, and has completed the primary price reduction process of Fe2O3→Fe3O4→FeO, and as a metallurgical process, it has saved 1 / 3 of the reducing C and the corresponding heat consumption; although the grade of Fe is not high and the amount of slag is too large, it seems to have no smelting value, in fact, there is only a sensible heat supplement of 200°C between the original slag and the final slag, which has no major impact on the smelting process. Compared with the original ore, it is a high-energy and low-cost raw material.

[0066] In the metallurgical process of the smelting method of the present invention, FeO is reduced and decomposed into:

[0067]

[0068] FeO exists in the original slag in the form of 2FeO.SiO2, but not always. Due to the reducing atmosphere and smelting temperature of nonferrous metallurgy, Fe is used for slag making and flux, and iron cannot be reduced. Therefore, the iron phase of the produced slag is iron olivine. If the reducing atmosphere and smelting temperature are increased, Fe can be reduced. Moreover, 2FeO.SiO2 is the result of chemical analysis under cooling state, and FeO under high temperature conditions may not be in the form of 2FeO.SiO2. They are in the scope of silicate engineering technology, not chemical bonds, and it is impossible for them to be too tightly combined with each other under high temperature.

[0069] The melting point of FeO is 1630℃, but in the multi-element phase diagram, the eutectic point is not high, so it is believed that FeO exists in the original slag in liquid state.

[0070] More importantly, C cannot directly participate in the reduction reaction of FeO. The present invention believes that all solid or liquid fuels (or reducing agents) must be gasified before combustion and reaction can occur. Many natural phenomena can explain this. Therefore, we believe that CO is a reducing agent, not solid C, and its reaction is a liquid-gas reaction. This is very important. The above chemical reaction equation reflects the process of the reaction and the result of the reaction.

[0071] In addition, the reduction reaction of FeO+CO=Fe+CO2, under the condition of reducing atmosphere, has a reaction temperature of 800℃~900℃, which means the reduction temperature is not high. For example, the direct reduction smelting temperature is controlled between 900℃~1100℃. The iron-containing slag is definitely liquid at 1250℃, but the melting point of the quaternary slag formed after Fe is reduced is increased, so the smelting temperature must be above 1500℃.

[0072] According to the above reaction equation, when the temperature of the generated CO2 reaches 900℃, in the presence of C, the reduction reaction of CO2+C=2CO will immediately occur, which will absorb a large amount of heat. If the heat is not replenished in time and in sufficient quantity, the cylinder will freeze immediately. This is also the reason why in the prior art, although in theory FeO can be reduced by adding carbon, it is difficult to implement in practice.

[0073] The reduction temperature is determined by the reduction reaction, which is about 900°C, while the smelting temperature is determined by the melting point of the slag, which must be about 1500°C. The two are not at the same level. In order to complete the smelting process, heat must be added in time and at the same place to ensure the smelting temperature of 1500°C. Therefore, this patent application proposes that FeO+CO=Fe+CO2, CO2+C=2CO and heat supply must be carried out at the same time, at the same place and synchronously, and none of them can be missing.

[0074] We use high melting point carbon (coke, pellet coke, natural coke) and add it into the furnace through the discharge flue. We will use mechanical operation to press the lighter carbon and quicklime into the mixed melt in the reaction zone to achieve a true density of 2.0t / m 3 , it will stay well in the mixed solution in the reaction zone, providing C guarantee for the CO2 reduction reaction of CO2+C=2CO. The coke in the mixed solution is subject to a small buoyancy. After calculation, the specific gravity of the mixed solution (slag+coke+quicklime) is 2.4t / m 3 , while the density of coke is 2.0t / m 3 , the difference is not big, which determines that the solid material area floating above the liquid surface in the reaction zone does not need to be very high.

[0075] In the thermal process, the precipitation zone is the main heating zone, where 70-80% of the electric heat is generated. Due to the heat transfer process, there is no radiation heat transfer, and the conduction heat transfer is also very weak, because the thermal conductivity of the slag is very poor. The only remaining heat transfer is convection heat transfer, but the melt in the furnace does not have a strong flow power, and only the phase interface between the precipitation zone and the reaction zone will produce a relative exchange of hot and cold melts. These reflect that the heat conduction process in the furnace is very poor.

[0076] According to heat consumption, the above reaction equation will consume 70-80% of the heat, while increasing the sensible heat of the raw slag and the heat dissipation of the furnace only accounts for a small part, estimated to be between 20% and 30%.

[0077] According to the heat supply and heat consumption, the present invention injects the raw slag (containing FeO slag) from the precipitation zone. Since the raw slag has a large specific gravity, it is infinitely interfused with the original slag after being injected into the precipitation zone, and is in the precipitation zone at the bottom of the furnace. The raw slag obtains heat in the precipitation zone and flows upward through the reaction zone. Since the bottom of the reaction zone has C, FeO and high temperature at the same time, the above-mentioned reduction reaction and slag-making smelting process occur at the interface between the precipitation zone and the reaction zone, realizing the reduction of FeO, the reduction of CO2 and heat supply, and realizing the simultaneous and synchronous operation of the three at the same time and in the same place. The heat demand of the reaction at the phase interface is like a black hole, which consumes a large amount of heat generated in the precipitation zone. In this way, the process is satisfied without causing the temperature of the precipitation zone to be too high. Because the temperature of the precipitation zone is too high, it is not good for the furnace lining.

[0078] The electric heat generated in the reaction zone can ensure that the remaining FeO continues to be reduced in the reaction zone, and can also ensure the smelting temperature of 1500°C in the reaction zone.

[0079] Since the smelting temperature of the reaction zone is guaranteed, the discharge of the final slag has good fluidity. After passing through the carbon zone of the reaction zone, the final slag reaches the liquid surface and is siphoned out below the liquid surface.

[0080] The invention has low investment, simple and reliable operation, and the iron recovery rate is close to 100%. The final slag has higher use value than the original slag, and only emits a minimum amount of low-temperature high-purity CO furnace gas, and the environmental and economic benefits are particularly obvious.

[0081] The smelting method and metallurgical device of non-ferrous metallurgical slag in the present invention further smelts the slag to recover iron. The slag temperature is 1250°C-1300°C. During the smelting process, only slight heating is needed to maintain the temperature required for smelting, and the energy consumption is low. The present invention uses mechanical thrust to make the reducing agent and flux contact the slag, ensuring that the iron in the slag can be fully reduced, and the recovery rate is high. The slag used in the present invention is non-ferrous metallurgical slag, which is iron-containing and a small amount of valuable metal liquid waste discharged from a side-blown furnace and a fuming furnace. It has low investment, simple and reliable operation, low energy consumption, few harmful impurities in the product, and particularly significant environmental and economic benefits. The smelting method of the present invention has an iron recovery rate of more than 99%. The final slag has a higher use value than the original slag, and only a very small amount of low-temperature high-purity CO furnace gas is discharged, and the environmental and economic benefits are particularly obvious.

[0082] The above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modification, equivalent substitution or improvement within the spirit of the present invention is included in the scope of the claims of the present invention.

Claims

1. A method for smelting nonferrous metallurgical slag, characterized in that: The molten slag is added into the molten pool smelting furnace, and the reducing agent and the flux are immersed in the molten slag; an electric current is passed through the molten slag, and the temperature of the slag is controlled at a smelting temperature of 1450° C. to 1800° C. by using the resistance heating of the molten slag, thereby completing the iron oxide reduction and slag making process.

2. The smelting method of nonferrous metallurgical slag according to claim 1, characterized in that: The slag exists in the molten pool smelting furnace in the form of a melt; the reducing agent and the flux are solid block materials, the reducing agent and the flux are added from above the slag, and accumulate in the furnace to form a solid material column, and the solid material column is partially immersed in the melt under the action of its own weight and / or mechanical pressure.

3. The smelting method of nonferrous metallurgical slag according to claim 1, characterized in that: Before the reducing agent and the flux come into contact with the slag, the reducing agent and the flux are preheated by utilizing the high-temperature furnace gas generated during the smelting process in the molten pool smelting furnace.

4. The smelting method of nonferrous metallurgical slag according to claim 1, characterized in that: The reducing agent includes coke, or a mixture of coke and coal.

5. The smelting method of nonferrous metallurgical slag according to claim 1, characterized in that: The flux includes quicklime, fluorite and / or caustic soda.

6. The smelting method of nonferrous metallurgical slag according to claim 1, characterized in that: The slag is liquid iron-containing slag.

7. The smelting method of nonferrous metallurgical slag according to claim 1, characterized in that: The electric heating is direct current heating; a top graphite electrode is arranged at the top of the molten pool smelting furnace, and a graphite bottom electrode is arranged at the bottom; the top graphite electrode is inserted from the top of the furnace down to a selected depth of the slag; the graphite bottom electrode is inserted from the bottom of the furnace and connected to the dead iron layer area at the bottom of the furnace, and the bottom graphite electrode and the dead iron layer at the bottom of the furnace together constitute the bottom electrode.

8. The smelting method of nonferrous metallurgical slag according to claim 1, characterized in that: The molten pool smelting furnace is provided with a material discharge flue at the upper part, a slag input port at the lower part, a molten iron discharge port at the lower part, and a molten final slag discharge port at the upper part.

9. The smelting method of nonferrous metallurgical slag according to claim 1, characterized in that The solid reducing agent and flux move from top to bottom, and the molten slag moves in countercurrent from bottom to top, so that the molten iron-containing slag contacts the solid reducing agent and flux.

10. The smelting method of nonferrous metallurgical slag according to claim 1, characterized in that: It also includes a pre-furnace, which is placed on one side of the molten pool furnace and is connected to the molten pool smelting furnace. Before the raw slag enters the molten pool smelting furnace, the pre-furnace is used for heating and keeping the raw slag warm.

11. The smelting method of nonferrous metallurgical slag according to claim 1, characterized in that: A material pressing pusher is arranged on the top of the molten pool smelting furnace, and the material pressing pusher can be reciprocated and lifted; during the reciprocating lifting process of the material pressing pusher, the reducing agent and the flux are pressed into the slag to a selected depth.

12. An ironmaking device for non-ferrous metallurgical slag, characterized in that: It comprises a molten pool smelting furnace, which is provided with a top graphite electrode and a graphite bottom electrode; the top graphite electrode can be raised and lowered; the molten pool smelting furnace is provided with a slag input port, a molten iron discharge port, a final slag discharge port and a material discharge flue; the material discharge flue is arranged at the upper part of the molten pool smelting furnace; a material pressing pusher is arranged on the top of the molten pool smelting furnace, and the material pressing pusher can be reciprocated and raised and lowered.

13. The ironmaking device for non-ferrous metallurgical slag according to claim 12, characterized in that: It also includes a power source, which is used to supply power so that the top graphite electrode, the bottom graphite electrode and the slag in the furnace form a current loop.

14. The ironmaking device for nonferrous metallurgical slag according to claim 12, characterized in that: The power supply is a direct current power supply, or the power supply is an alternating current power supply, and further includes a rectifier transformer, and the alternating current is inverted into direct current through the rectifier transformer.

15. The ironmaking device for nonferrous metallurgical slag according to claim 12, characterized in that: It also includes a pre-furnace, which is used to heat and / or keep the slag warm; the pre-furnace is connected to the molten pool smelting furnace.

16. The ironmaking device for nonferrous metallurgical slag according to claim 15, characterized in that: The pre-furnace is an electric heating furnace.

17. The ironmaking device for nonferrous metallurgical slag according to claim 12, characterized in that: The slag inlet is located lower than the final slag outlet and higher than the molten iron outlet.

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