Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
  • C21C5/56—Manufacture of steel by other methods
  • C21C5/567—Manufacture of steel by other methods operating in a continuous way
• • 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
• • 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
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• the invention relates to metallurgy and can be used for the efficient processing of red mud, by-products of the production of alumina.
• Red mud is a finely divided substance, an environmentally harmful product containing a large amount of alkali NaOH and up to 50% moisture.
• the moisture content in red mud can be reduced only to 25%.
• Storage of red mud in special sludges requires significant costs, constant monitoring of the state of sludge storages and poses a serious danger to the surrounding territories.
• red muds contain a significant amount of iron oxides (up to 55%), comparable with the content of iron oxides in medium-quality iron ores.
• red mud contains a significant amount of titanium oxides, quite a lot of alumina A1 2 0z. Therefore, the processing of red mud with the extraction of its useful components, primarily iron, can be cost-effective.
• Pyrometallurgical methods for processing red mud have a number of advantages, the main of which is the possibility of practically waste-free processing of mud, with the receipt of marketable products that are in demand on the market.
• the disadvantages of pyrometallurgical methods for processing red mud are the need to use coolants to maintain the high temperature of the process and, most importantly, the need to dry the red mud (lowering the humidity to 10%) before loading into the melting unit.
• the red mud must be pelletized, having received pellets, such a process is expensive and inefficient;
• an addition to the red mud is provided for the preparation of a portion of the charge of a titanium magnetite ore concentrate containing from 1 to 15% titanium, as well as an additional amount of a carbon reducing agent and other materials.
• the cast iron is heated to 1500-1550 ° C, a product containing iron oxide is added to it, from which iron is reduced by carbon of cast iron to convert cast iron to steel to obtain secondary slag. Then the main part of the steel is removed from the smelter, the secondary slag is added to primary, of which silicon and titanium are transferred to the remainder of the steel in the smelter by reduction with aluminum to obtain the final slag and ligature containing iron, titanium, silicon saturated with aluminum (obviously, aluminum oxide).
• the main part of the ligature is removed from the smelting unit, after removal of the final slag, the titanium and silicon of the ligature residue are oxidized and the next portion of the recovered charge is fed into the slag phase formed after the ligature residue is converted to steel.
• the final slag saturated with alumina is removed from the unit after the central part of the hearth of the melting unit is freed from ligature, carried out by rotation of the ligature residues by the electromagnetic field.
• the transfer of the ligature residue into the slag phase of titanium and silicon is carried out by purging with air and / or oxygen supplied through sacrificial iron tubes.
• the next portion of the recovered charge is fed into the slag phase formed after the transfer of the ligature residues to steel, which is rotated in the melting unit by an electromagnetic field.
• the method does not explain how, in a subsequent production cycle, the recovered charge (where was it recovered in another unit?) is fed into the slag phase formed after the remnant of the ligature is transferred to steel;
• the proposed method of pyrometallurgical processing of red muds solves the problem of creating a process of high-performance and efficient processing of red muds.
• the red mud processing carried out in one stage further includes heating and drying the sludge in the drying device to a moisture content of 6-10% by heat of the gases leaving the smelting unit with a temperature of 1750-1850 ° C, into the drying the device to the wet red mud add 3-6% by weight of the sludge of lime production waste containing%:
• dried red mud with a pressurized loading device is loaded from the dryer onto molten slag obtained during the processing of sludge heated to 1640-1680 ° C at a rate of 1, 2-1.4 tons per 1 m 2 of molten slag mirror per hour, iron recovery from the molten mixture is produced with carbon-containing materials loaded onto the slag in an amount ensuring the content of iron oxides in the reduced final slag in the range of 3-5%; separate discharge of the melting products is carried out continuously or periodically, supporting fluctuations in the level of the melt in the melting unit by no more than 200-300 mm due to changes in the drain rate and the amount of smelting products.
• carbon monoxide CO exhaust gases from the smelting unit is used for partial solid-state reduction of iron.
• the content of iron oxides in the reduced slag is adjusted by changing the amount of gaseous oxygen supplied to the fuel-oxygen burners at a constant flow rate of the carbon reducing agent.
• the melting and heating of the charge materials loaded into the melting unit is carried out due to the heat obtained by oxidizing the carbon materials introduced in the required amount with gaseous oxygen, injected with water-cooled lances into the melting unit at a supersonic speed.
• the dried red mud is injected into the melt in the melting unit by injectors.
• red mud is carried out in a continuous fuel and oxygen skull melting unit with cooling of the metal body of the unit with a liquid metal coolant.
• 35-45% of the used carbon reducing agent is loaded into the drying unit together with red mud.
• the reduced low-iron slag is poured from the smelter into an arc furnace with a carbon lining of the bath and a complex alloy Fe-Si-Al-Ti and calcium-aluminum slag are obtained from it by carbon thermal reduction.
• the implementation of the processing of red mud in one stage can significantly increase the performance of the smelter and simplify the processing technology.
• red mud to a moisture content of 6-10% with the exhaust gases from the smelter at a temperature of 1750-1850 ° C makes it possible to safely process sludge without fear of explosion when wet sludge enters the molten heated slag, and also significantly increase the thermal efficiency of the unit. Drying red mud to a moisture content of less than 6% causes a decrease in the productivity of the drying device and will require a significant increase in the size and, accordingly, the cost of the drying device. A moisture content in the loaded red mud of more than 10% can lead to an explosion when it is processed in the smelter.
• the temperature of the gases leaving the melting unit is less than 1750 ° C, and therefore the same temperature of the gases in the working space of the melting unit above the melt, it is possible to heat the slag melt and reduce the speed and completeness of iron reduction from the molten sludge.
• the use of carbon monoxide ⁇ of the exhaust gases for partial solid-phase reduction of iron during heating and drying of red mud reduces the consumption of carbon reducing agent and increases the productivity of a smelter that processes red mud.
• waste lime production in an amount of less than 3% by weight of red mud does not give a sufficient (due) effect.
• the loading of dried red mud from the drying device into the melting unit on molten slag obtained during the processing of sludge heated to 1640-1680 ° C at a speed of 1.2-1.4 tons per 1 m 2 of molten slag mirror per hour provides the highest speed penetration of sludge and reduction of iron from it.
• the charge loading speed is more than 1.4 tons per 1 m 2 of the melt mirror, the loaded charge does not have time to completely melt and heat up to the required temperature. This leads to a decrease in the temperature of the slag melt, a decrease in the rate of iron reduction, makes it difficult to separate droplets of the reduced iron alloy from the slag, and worsens the performance of the red mud processing.
• the loading of carbonaceous materials for iron reduction to the slag in such an amount that the content of iron oxides in the reduced final slag is within 3-5% increases the speed of the red mud processing and allows obtaining the final slag with high mechanical properties suitable for the production of building materials and slag products.
• the content of iron oxides in the reduced final slag of less than 3% does not allow to obtain the necessary high mechanical properties of the slag and reduces the performance of the sludge processing process.
• the content of iron oxides in the final slag of more than 5% although it provides the necessary mechanical properties of the slag, leads to a deterioration in the performance of the sludge processing process as a result of a decrease in the yield of reduced iron in the form of cast iron (reduces the yield of cast iron from the processed sludge).
• Fluctuation (decrease) in the level of the melt in the melting unit when the melting products are released by more than 300 mm results in a significant amount of slag dropping into the metal bath and accelerating the wear of the refractory lining of the metal bath.
• a decrease in the level of the melt in the melting unit when releasing melting products by less than 200 mm is possible only with a very low speed of release and a small amount of melted products being drained.
• This option is disadvantageous because it reduces the performance of the unit and reduces the temperature of the melting products in the casting ladles.
• the injection of dried red mud by injectors into the melt located in the smelting unit makes it possible to simplify the scheme of loading sludge into the aggregate and reduce the capital costs of constructing the aggregate for processing red mud.
• the loading of 30-45% of the carbon reducing agent used in the drying unit together with the red mud ensures accelerated drying of the sludge due to the additional heat input during partial oxidation of the reducing agent, enhances the solid-state reduction of iron and improves the productivity of the melting aggregate.
• Figure 1 shows the technological scheme of the proposed method of pyrometallurgical processing of red mud.
• the method of pyrometallurgical processing of red mud is as follows.
• Red sludge with a moisture content of not more than 25% is loaded into the drying unit 1, to which wastes of lime production in the amount of 3-5% by weight of the sludge are added.
• Low-melting waste of ferrous metals (cast iron and steel shavings, pig iron, small steel trimmings) is loaded into the melting unit 2 through the loading hole 3 in the housing.
• the fuel-oxygen burners 4 are turned on and a liquid metal bath is deposited in order to prevent the refractory lining of the metal bath from being destroyed by the overheated slag melt.
• the gases passing through the loading hole 3 from the melting unit with a temperature of 1750-1850 ° C pass through the drying unit, as a result, the moisture of the red mud is reduced to 6-10%, in the high temperature zone in the drying unit of the exhaust gas ⁇ solid-phase reduction of iron.
• the dried charge is loaded into the melting unit first on the metal and then on the formed slag melt at a speed of 1.2-1.4 tons per 1 m 2 of the melt mirror per hour.
• the slag heated to 1640-1680 ° C is charged with carbon-containing materials in the amount of iron oxides in the recovered final slag in the range of 3-5% through loading hole 3. If necessary, the content of iron oxides in the reduced final slag is adjusted at a constant consumption of the carbon reducing agent by changing the amount of oxygen supplied to the fuel-oxygen burners 4, droplets of the reduced iron are deposited from the slag melt 6 into the metal bath 7, carbonized during passage through the slag melt. In this case, the metal level in the metal bath increases.
• the resulting molten iron and the recovered final slag are separately poured from the melting unit through flight devices 8, 9 into cast iron 10 and slag-filling ladles 1 1 at such a speed and in such quantity that the melt level in the melting unit does not fluctuate by more than 200-300 mm. This allows you to increase the resistance of the refractory lining of a metal bath, to increase the productivity of the process of processing red mud.
• Part or all of the dried sludge can be blown into the slag melt by injectors 12, the dust collected in the gas purification 13 is blown into the melt by the same injectors 13.
• a part (30-45%) of the used carbon reducing agent can be loaded into the drying device to accelerate the drying of the charge and improve the technical and economic indicators of the process of processing red mud.
• the proposed method for processing red sludge is carried out in a continuous fuel-oxygen skull melting unit 2, the body of which is cooled by a liquid metal coolant in order to increase the continuous operation of the melting unit and reduce the consumption of refractories.
• the melting and heating of the charge materials loaded into the melting unit is carried out due to the heat obtained during the oxidation of solid carbon-containing materials introduced through the loading hole 3 by gaseous oxygen injected into the melting unit at a supersonic speed by water-cooled tuyeres 4.
• the recovered final low-iron slag is poured from the smelter into an arc furnace with a carbon lining of the bath and, at high temperature, the complex Fe-Si-Al-Ti alloy and calcium-aluminum slag are obtained from it by carbon thermal reduction.
• Patent RU 2016099 C1. A method of producing iron ore sinter.
• Patent RU 2086659 C A method of processing iron-alumina raw materials.
• the method of disposal of red mud is a waste of alumina production.
• Patent RU 2245371 C2. A method of processing red mud of alumina production.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Metallurgy (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Geology (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Gasification And Melting Of Waste (AREA)
• Treatment Of Sludge (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=48290367

Family Applications (1)

Country Status (3)

Cited By (4)

Families Citing this family (5)

Citations (4)

• 2011
  • 2011-11-07 RU RU2011145140/02A patent/RU2479648C1/ru not_active IP Right Cessation
• 2012
  • 2012-11-16 WO PCT/RU2012/000946 patent/WO2013070121A1/ru not_active Ceased
  • 2012-11-16 IN IN1026MUN2014 patent/IN2014MN01026A/en unknown

Patent Citations (5)

Also Published As

Similar Documents

Legal Events