CN211921662U

CN211921662U - Rotary hearth furnace for recycling production of metallurgical dust and sludge

Info

Publication number: CN211921662U
Application number: CN202020138702.7U
Authority: CN
Inventors: 王�锋; 严定鎏; 万新宇; 高建军; 齐渊洪
Original assignee: Central Iron and Steel Research Institute; CISRI Sunward Technology Co Ltd
Current assignee: Central Iron and Steel Research Institute; CISRI Sunward Technology Co Ltd
Priority date: 2020-01-21
Filing date: 2020-01-21
Publication date: 2020-11-13
Anticipated expiration: 2030-01-21

Abstract

The utility model relates to a rotary hearth furnace for metallurgical dust and mud resource production again belongs to rotary hearth furnace technical field, has solved the problem that current rotary hearth furnace can't satisfy the high-efficient resource production again of metallurgical dust and mud. The utility model discloses a rotary hearth furnace, which comprises a rotary hearth furnace body, a water seal unit and an air supply unit, wherein the rotary hearth furnace body comprises an annular fixed furnace body and an annular rotary furnace bottom arranged at the bottom of the annular fixed furnace body, and the annular fixed furnace body and the annular rotary furnace bottom are sealed by the water seal unit; the bottom end of the annular rotating furnace bottom is provided with a bottom plate provided with a first hole, a mixture is paved on the bottom plate, an air supply unit is arranged below the bottom plate and used for providing combustion-supporting gas for the mixture, and the air supply unit synchronously rotates along with the annular rotating furnace bottom; a single exhaust port is arranged at the top of the annular fixed furnace body, the exhaust port is communicated with the heat exchanger and the dust remover, and the flue gas after dust removal is discharged after being qualified through desulfurization and denitration. Realizes the high-productivity production of recycling the metallurgical dust and mud.

Description

Rotary hearth furnace for recycling production of metallurgical dust and sludge

Technical Field

The utility model relates to a rotary hearth furnace technical field especially relates to a rotary hearth furnace for metallurgical dirt mud resourceful production again.

Background

A large amount of waste iron-containing dust and mud containing zinc and lead are generated by steel plants every year, blast furnaces are not suitable for use, the discharge output of the blast furnaces is limited by environmental protection, and how to economically recover the waste iron-containing dust and mud is a difficult problem which troubles the metallurgical industry, so that the coal-based reduction of the rotary hearth furnace becomes a main technological measure for recycling solid waste resources at present.

The most prominent characteristic of the existing rotary hearth furnace is that cold-bonded carbon-containing pellets are used, metallurgical waste is used as iron-containing raw material, coke powder or coal is used as internal reducing agent, raw fuel is mixed and ground uniformly to produce cold-bonded pellets, then the cold-bonded pellets are continuously added into the rotary hearth furnace, and a layer of furnace burden is uniformly distributed on a furnace plate. Burners are arranged around the furnace plate, natural gas is used as fuel, high-temperature fuel gas is blown into the furnace and flows in the direction opposite to the direction of the furnace plate, and heat is transferred to furnace materials.

However, the rotary hearth furnace has some problems, for example, the rotary hearth furnace process suffers from the disadvantages of the industry due to the factors of large investment, low yield of the hearth per unit area, need of high-calorific-value gas as fuel and the like, the advantages of the rotary hearth furnace are gradually lost in the competition with the rotary kiln, and the rotary kiln also has the inherent defects due to the easy ring formation and low operation rate, so that the rotary hearth furnace has to be innovated in process technology and equipment to improve the competitiveness, and becomes an effective replacement process and device for the traditional rotary hearth furnace and the rotary kiln.

SUMMERY OF THE UTILITY MODEL

In view of the above analysis, the utility model aims at providing a rotary hearth furnace for metallurgical dirt mud resourceful production again for solve the technical problem that current rotary hearth furnace can't satisfy the high-efficient resourceful production of metallurgical dirt mud again.

The purpose of the utility model is mainly realized through the following technical scheme:

the utility model discloses a rotary hearth furnace for recycling production of metallurgical dust and mud, which comprises a rotary hearth furnace body, a water seal unit and an air supply unit, wherein the rotary hearth furnace body comprises an annular fixed furnace body and an annular rotary furnace bottom arranged at the bottom of the annular fixed furnace body, and the annular fixed furnace body and the annular rotary furnace bottom are sealed by the water seal unit;

the bottom end of the annular rotating furnace bottom is provided with a bottom plate provided with a first hole, a mixture is paved on the bottom plate, the air supply unit is arranged below the bottom plate and used for providing combustion-supporting gas for the mixture, and the air supply unit synchronously rotates along with the annular rotating furnace bottom.

In one possible design, the bottom plate is laid by adopting a grate, gaps among the grate and the bottom plate form first holes when the grate is laid, annular retaining walls are arranged at the inner side and the outer side of the annular rotary furnace bottom, and the height of a mixed material layer on the grate is equal to that of the annular retaining walls.

In one possible design, second holes are uniformly distributed on the inner side and the outer side of the annular fixed furnace body along the circumferential direction, secondary combustion burners are arranged on the second holes, and the secondary combustion burners are used for supplementing combustion-supporting gas into a hearth of the rotary hearth furnace.

In one possible design, the air supply unit comprises a plurality of air distribution air boxes arranged below the annular rotating furnace bottom, the air distribution air boxes are uniformly distributed along the circumferential direction of the annular rotating furnace bottom, and the air distribution air boxes are communicated with the annular rotating furnace bottom and synchronously rotate;

and combustion-supporting gas enters the mixed material layer through the corresponding air distribution bellows and the first holes.

In one possible design, the air supply unit further comprises an annular gas supply pipe and an annular air distribution pipe connected with a fan, the upper part of the annular air distribution pipe is opened to form an annular through groove, an inverted U-shaped annular cover plate is arranged at the top of the annular through groove, an air inlet hole is formed in the top plate of the inverted U-shaped annular cover plate along the circumferential direction, and the inner side plate and the outer side plate of the inverted U-shaped annular cover plate are respectively matched with the inner side wall and the outer side wall of the annular through groove, so that the inverted U-shaped annular cover plate can move circumferentially along the annular through groove, combustion-supporting gas is conveyed into the annular air distribution pipe through the fan, and enters the mixture layer through the annular through groove, the air inlet hole of the inverted; the inverted U-shaped annular cover plate is suspended at the bottom of the annular rotating furnace bottom through a steel structure and synchronously rotates with the annular rotating furnace bottom;

the annular gas supply pipe and the annular air distribution pipe are identical in structure and are arranged in the same circle center, namely a plurality of annular gas supply pipes and a plurality of annular air distribution pipes are respectively arranged on two concentric circles with different radiuses. Specifically, an annular through groove is formed in the upper portion of the annular gas supply pipe in an opening mode, an inverted U-shaped annular cover plate is arranged at the top of the annular through groove, an air inlet hole is formed in the top plate of the inverted U-shaped annular cover plate in the circumferential direction, the inner side plate and the outer side plate of the inverted U-shaped annular cover plate are respectively matched with the inner side wall and the outer side wall of the annular through groove, the inverted U-shaped annular cover plate can move circumferentially along the annular through groove, gas is conveyed into the annular gas supply pipe through a fan, and enters a mixture layer through the annular through groove, the air inlet hole of the inverted U-shaped annular cover plate; the inverted U-shaped annular cover plate is suspended at the bottom of the annular rotating furnace bottom through a steel structure and synchronously rotates with the annular rotating furnace bottom.

In one possible design, the air supply unit further comprises a plurality of air inlet pipes, and one ends of the air inlet pipes are connected with the air supply bellows; the air inlet pipe comprises an air inlet main pipe, a first air inlet branch pipe and a second air inlet branch pipe; the other end of the air inlet pipe is communicated with the annular air distribution pipe through a first air inlet branch pipe and is communicated with the annular gas supply pipe through a second air inlet branch pipe; the main air inlet pipe is a sleeve pipe and comprises an inner pipe and a circular seam pipe, the inner pipe is communicated with one end of the first air inlet branch pipe, and the circular seam pipe is communicated with one end of the second air inlet branch pipe;

combustion-supporting gas enters the mixed material layer through the annular air distribution pipe, the annular through groove, the air inlet hole, the air inlet pipe, the air distribution bellows and the first holes; the fuel gas enters the mixed material layer through the annular fuel gas supply pipe, the annular through groove, the air inlet hole, the air inlet pipe, the air distribution air box and the first holes.

In one possible design, the inverted U-shaped annular cover plate comprises an annular top plate, an annular inner side plate and an annular outer side plate, and the annular top plate is provided with an air inlet hole; a first annular water tank is arranged on the inner side of the annular through groove, a second annular water tank is arranged on the outer side of the annular through groove, an annular inner side plate of the inverted U-shaped annular cover plate is inserted into the first annular water tank, and an annular outer side plate of the inverted U-shaped cover plate is inserted into the second annular water tank; the first annular water tank and the second annular water tank are used for sealing air between the annular air distribution pipe and the inverted U-shaped annular cover plate.

In one possible design, the outer wall of the air distribution bellows is provided with an air blower connected with a variable frequency motor, the variable frequency motor gets electricity through a sliding contact line, and the outlet of the air blower is communicated with the corresponding air distribution bellows through a pipeline; the blower is used for supplementing combustion-supporting gas to the air distribution bellows.

In one possible design, the inner side of the annular air distribution pipe is provided with heat-insulating refractory materials.

In a possible design, the water seal unit comprises an annular water seal groove, the annular water seal groove is arranged on the outer side of the bottom plate, a water seal scraper is arranged on the groove wall of the annular water seal groove, the bottom of the water seal groove is communicated with the sludge deposition groove, a blow-off pipe is arranged in the sludge deposition groove, sludge is pumped into the sedimentation tank through the blow-off pipe by a sewage pump, and precipitated water is introduced into the annular water seal groove again.

In one possible design, the rotary hearth furnace further comprises a feeding unit, the feeding unit comprises a conical roller type distributor, the conical roller type distributor is arranged on the annular fixed furnace body along the radial direction, the conical roller type distributor comprises a conical roller, the roller diameter of the conical roller is gradually reduced from the outer side to the inner side, a distributing groove is formed in the conical roller, and the distributing groove rotates along with the conical roller;

the mixture enters the bottom plate paved with the grate bars through the conical rollers and the distribution grooves.

In one possible design, a plurality of material distribution rings are uniformly distributed on the conical roller along the circumferential direction of the conical roller, and material distribution grooves are uniformly distributed along the circumferential direction of the material distribution rings; the charging amount of the distributing chute corresponds to the area of the hearth.

In a possible design, the feeding unit further comprises a scraper, the scraper is fixed in the annular fixed furnace body through a connecting steel plate, the scraper is arranged on the rear side of the conical roller type distributor, and the scraper is used for scraping the mixture distributed on the bottom plate.

In a possible design, a water cooling part is arranged in the scraper, the water cooling part comprises a cooling water inlet and a cooling water outlet which are arranged at one end of the scraper, a cooling water conveying pipe which is arranged in parallel is arranged in the scraper, one end of the cooling water conveying pipe is communicated with the cooling water inlet, and the other end of the cooling water conveying pipe is communicated with the cooling water outlet.

In one possible design, the discharging unit comprises a material shoveling device and a spiral discharging device, the spiral discharging device is arranged on the annular fixed furnace body, and the material shoveling device is used for lifting the furnace burden to the upper part of the annular retaining wall at the bottom of the annular rotating furnace and then discharging the furnace burden out of the furnace through the fixed spiral discharging device.

In a possible design, the annular rotating furnace bottom is connected with a furnace bottom driving device, the furnace bottom driving device comprises a driving motor, and the driving motor drives the mixed material layer on the annular rotating furnace bottom to rotate for a circle and then discharge through a discharging unit.

In one possible design, the top of the annular fixed furnace body is provided with a first exhaust port and a second exhaust port, and the first exhaust port is used for recovering unqualified zinc oxide powder at the early stage volatilization part; the second exhaust port is used for recovering qualified zinc oxide powder at the later stage volatilization part; the first exhaust port and the second exhaust port are communicated with the heat exchanger and the dust remover, and the flue gas after dust removal is discharged after being qualified through desulfurization and denitration.

Compared with the prior art, the invention can realize at least one of the following beneficial effects:

(1) the invention relates to a traditional rotary hearth furnace which supplies heat by burning high-calorific-value coal gas through an upper burner, changes the heat supply mode of the traditional rotary hearth furnace, classifies different types of solid waste resources or industrial zinc oxide production raw materials or iron ore concentrate to be treated and necessary amount of coal powder into a storage bin, mixes the materials in proportion by a metering and feeding facility arranged below the storage bin, uniformly mixes the materials by a mixing device, directly distributes the mixture into the rotary hearth furnace through a conveying device and a conical roller type distributor, ignites the mixture by an ignition device, blows air, oxygen-enriched air and fuel gas into a hearth of the rotary hearth furnace through an air supply unit to provide necessary conditions for the combustion of carbon in a mixture layer, heats the mixture to the temperature required by direct reduction reaction by the heat released by the combustion of the carbon, and effectively recycles and utilizes related valuable metal oxides in the mixture layer to generate direct reduction reaction with the carbon.

(2) The bottom plate of the invention is paved by adopting the grate bars, gaps are reserved between the grate bars to form first holes which are round or square, and annular retaining walls with the same height are arranged on the inner side and the outer side of the bottom plate, so that the discharge of the mixture can be prevented, the charging amount of the mixture on the bottom plate can be improved (namely the thickness of the mixture layer is increased), after combustion-supporting gas (comprising combustion-supporting air, oxygen-enriched air or preheated air) and fuel gas provided by the air supply unit enter the mixture layer through the first holes, the mixture is promoted to complete physicochemical processes of combustion, heating, reduction and the like, the thick-layer operation can be finally realized, high-heat-value gas is not needed, the area of a furnace bed can be greatly reduced on the premise of the same capacity, the equipment investment is reduced, and the competitiveness of the rotary hearth furnace process is improved.

(3) According to the invention, the secondary combustion burner is arranged on the annular fixed furnace body, and the secondary combustion burner is used for supplementing combustion-supporting gas to secondarily oxidize substances such as fuel gas, zinc vapor and the like overflowing from the material layer, and generate certain heat to reversely heat the mixture, so that the primary energy consumption of the rotary hearth furnace is effectively reduced.

(4) The air supply unit is arranged at the bottom of the annular rotating furnace bottom, and combustion-supporting gas enters the mixed material layer through the annular air distribution pipe, the annular through groove, the air inlet hole, the air inlet pipe, the air distribution air box and the first holes; the gas enters the mixed material layer through the annular gas supply pipe, the annular through groove, the air inlet hole, the air inlet pipe, the air distribution air box and the first holes, and carbon in the mixed material layer can be fully combusted after blast ignition, so that heat is supplied to the rotary hearth furnace; the method changes the radiation heat supply mode of the traditional rotary hearth furnace through the upper burner, and can realize the laying of a thicker mixed material layer on the bottom plate by arranging the air supply unit below the bottom plate, thereby greatly improving the productivity of unit hearth area and having low unit productivity investment; the carbon in the mixture is a reducing agent and a heating agent, and the carbon in the mixture layer is combusted to supply heat, so that the dependence of the traditional rotary hearth furnace on high-calorific-value coal gas is eliminated, and a new path is provided for non-coke smelting.

The utility model discloses in, can also make up each other between the above-mentioned each technical scheme to realize more preferred combination scheme. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout the drawings.

FIG. 1 is a schematic view of a rotary hearth furnace according to embodiment 1 of the present invention;

fig. 2 is a schematic view of a material shoveling device and a material discharging device provided in embodiment 1 of the present invention;

fig. 3 is a schematic structural view of a conical roller type distributor provided in embodiment 1 of the present invention;

FIG. 4 is a top plan view of the rotary hearth furnace;

fig. 5 is a schematic structural diagram of an annular air distribution pipe.

Reference numerals:

1-ring-shaped fixed furnace body; 2-annular rotating furnace bottom; 3-furnace bottom driving device; 4-air distribution bellows; 5-a first air inlet branch pipe; 6-a material shoveling device; 7-water seal scraper; 8-water sealing the tank; 9-a sludge deposition tank; 10-a sewage draining pipe; 11-a support frame; 12-a spiral discharger; 13-annular air distribution pipes; 14-annular through groove; 15-an inverted U-shaped annular cover plate; 16-temperature refractory material; 17-a first annular water tank; 18-conical roller type distributor; 19-a rotary hearth furnace body; 20-a second annular water tank; 21-blower.

Detailed Description

The following detailed description of the preferred embodiments of the invention, which is to be read in connection with the accompanying drawings, forms a part of the invention, and together with the embodiments of the invention, serve to explain the principles of the invention and not to limit the scope of the invention.

Example 1

The embodiment discloses a rotary hearth furnace for recycling metallurgical dust and mud, which comprises a rotary hearth furnace body 19, a water seal unit and an air supply unit, wherein the rotary hearth furnace body comprises an annular fixed furnace body and an annular rotary hearth 2 arranged below the annular fixed furnace body 1, and the annular fixed furnace body 1 and the annular rotary hearth 2 are sealed through the water seal unit; the bottom end of the annular rotating furnace bottom 2 is a bottom plate provided with a hole, a mixture is paved on the bottom plate, an air supply unit is arranged below the bottom plate and used for providing combustion-supporting gas for the mixture, and the air supply unit rotates along with the annular rotating furnace bottom 2.

Specifically, the rotary hearth furnace comprises a rotary hearth furnace body 19, a water seal unit and an air supply unit, wherein the rotary hearth furnace body 19 comprises an annular fixed furnace body 1 and an annular rotary furnace bottom 2, the annular rotary furnace bottom 2 is arranged right below the annular fixed furnace body 1, and the annular fixed furnace body 1 and the annular rotary furnace bottom 2 are sealed through the water seal unit; the annular rotary furnace bottom 2 is connected with a furnace bottom driving device 3, and the annular rotary furnace bottom 2 can realize rotation under the driving of the furnace bottom driving device 3; the bottom end of the annular rotating furnace bottom 2 is a bottom plate, holes are formed in the bottom plate, and when the mixture is laid on the bottom plate, combustion-supporting air, oxygen-enriched air or preheated air supplied by the air supply unit enters the mixture layer through the holes to support combustion of the mixture. It should be noted that the air supply unit is arranged below the bottom plate, and the air supply unit synchronously rotates along with the annular rotating furnace bottom.

The invention relates to a traditional rotary hearth furnace which supplies heat by burning high-calorific-value coal gas through an upper burner, changes the heat supply mode of the traditional rotary hearth furnace, classifies different types of solid waste resources or industrial zinc oxide production raw materials or iron ore concentrate to be treated and necessary amount of coal powder into a storage bin, mixes the materials in proportion by a metering and feeding facility arranged below the storage bin, uniformly mixes the materials by a mixing device, directly distributes the mixture into the rotary hearth furnace through a conveying device and a conical roller type distributor 18, ignites the mixture by an ignition device, blows combustion-supporting gas (including combustion-supporting air, oxygen-enriched air or preheated air) and fuel gas into a hearth of the rotary hearth furnace through an air supply unit, provides necessary conditions for the combustion of carbon in a mixture layer, heats the mixture to the temperature required by direct reduction reaction by the heat released by the combustion of the carbon, and directly reduces relevant valuable metal oxides in the mixture layer and the carbon, is effectively recycled.

In order to realize the direct reduction of the powdery materials, the bottom plate of the annular rotary furnace bottom 2 is paved by using a grid section, a first hole is formed when the grid section is paved, annular retaining walls with the same height are arranged at the inner side and the outer side of the annular rotary furnace bottom 2, and the height of a mixed material layer on the grid section is less than or equal to the height of the annular retaining walls.

Specifically, the bottom plate is paved by adopting a grate, gaps are reserved among the grate to form first holes when the grate is paved, and the first holes are round or square; the inner side and the outer side of the bottom plate are both provided with annular retaining walls with the same height, the area formed by the annular retaining wall on the inner side, the annular retaining wall on the outer side and the bottom plate is a mixture placing area, and the annular retaining wall on the inner side and the annular retaining wall on the outer side are used for preventing mixture from being discharged outwards and improving the charging amount of the mixture on the bottom plate; wherein, the height of the annular retaining wall is the maximum height of the mixed material layer; after combustion-supporting gas (including combustion-supporting air, oxygen-enriched air or preheated air) and fuel gas provided by the air supply unit enter the mixed material layer through the first hole, the mixed material rotates along with the annular rotating furnace bottom 2, simultaneously, physical and chemical processes such as combustion, heating, reduction and the like are completed, the mixed material which rotates for a circle and completes roasting is discharged out of the rotary hearth furnace and directly enters the finished product bin, and flue gas generated by combustion and reaction is discharged after being processed by the flue gas processing unit.

In order to reduce energy consumption, second holes are uniformly distributed on the inner side wall and the outer side wall of the annular fixed furnace body 1 along the circumferential direction, the second holes are used for installing secondary combustion burners, and the secondary combustion burners are used for supplementing combustion-supporting gas into a hearth of the rotary hearth furnace.

Specifically, second holes with the same height are formed in the inner side wall and the outer side wall of the annular fixed furnace body 1 and are arranged along the circumferential direction of the annular fixed furnace body 1, and secondary combustion burners are correspondingly arranged in the second holes and penetrate through the inner side wall and the outer side wall of the annular fixed furnace body 1; the secondary combustion burner is used for supplementing combustion-supporting gas (comprising combustion-supporting air, oxygen-enriched air or preheated air) into a hearth of the rotary hearth furnace, related valuable metal oxides in the mixed material layer and carbon are subjected to direct reduction reaction, metal steam such as CO gas or zinc generated by direct reduction is subjected to secondary combustion through air supplemented by the secondary combustion burner on the upper part of the material bed, and the mixed material can be heated by heat generated by secondary combustion; through setting up the afterburning nozzle and utilizing its supplementary combustion-supporting gas can make full use of the heat energy and the chemical energy in the reaction process, reduce once energy consumption, the flue gas is discharged into the atmosphere after handling up to standard by flue gas processing unit.

In order to uniformly provide combustion-supporting gas for the mixed material layer, the air supply unit comprises a plurality of air distribution air boxes 4 arranged below the annular rotating furnace bottom 2, the air distribution air boxes 4 are uniformly distributed along the circumferential direction of the annular rotating furnace bottom 2, and the air distribution air boxes 4 are communicated with the annular rotating furnace bottom 2 and synchronously rotate; combustion-supporting gas (including combustion-supporting air, oxygen-enriched air or preheated air) enters the mixed material layer through the corresponding air distribution air box 4 and the first holes.

Specifically, the below at the bottom of annular rotation stove 2 is located to the air feed unit, and the air feed unit includes a plurality of four pyramid shape cloth wind bellows 4 that fall, and four pyramid shape cloth wind bellows 4 set up along 2 circumference equipartitions at the bottom of annular rotation stove, and the four pyramid shape cloth wind bellows 4 that fall rotates with annular rotation stove bottom 2 synchronous revolutions, and combustion-supporting gas gets into in the mixture layer through four pyramid shape cloth wind bellows 4 and first hole.

In the traditional rotary hearth furnace, high-calorific-value gas is combusted by an upper burner to supply heat through radiation, the laying thickness of a material layer on a hearth cannot be too thick, and the mixed material layer cannot be fully combusted due to too thick material layer; the air supply unit is arranged at the bottom of the annular rotary hearth 2, combustion-supporting gas is blown into the mixed material layer through the first holes in the bottom plate, and carbon in the mixed material layer can be fully combusted after blast ignition, so that heat is supplied to the rotary hearth; on one hand, the method changes the radiation heat supply mode of the traditional rotary hearth furnace through the upper burner, and can realize the laying of a thicker mixed material layer on the bottom plate by arranging the air supply unit below the bottom plate, thereby greatly improving the productivity of unit hearth area and having low unit productivity investment; on the other hand, carbon in the mixture is not only a reducing agent, but also a heating agent, and heat is supplied by combustion of the carbon in the mixture layer, so that the dependence of the traditional rotary hearth furnace on high-calorific-value coal gas is eliminated, and a new path is provided for the coke-free smelting.

In order to supply combustion-supporting gas and fuel gas to the annular rotary furnace bottom, the air supply unit further comprises an annular gas supply pipe and an annular air distribution pipe 13 connected with a fan, an opening in the upper part of the annular air distribution pipe 13 forms an annular through groove 14, an inverted U-shaped annular cover plate 15 is arranged at the top of the annular through groove 14, an air inlet hole is formed in the top plate of the inverted U-shaped annular cover plate 15 along the circumferential direction, an inner side plate and an outer side plate of the inverted U-shaped annular cover plate 15 are respectively matched with the inner side wall and the outer side wall of the annular through groove 14, so that the inverted U-shaped annular cover plate 15 can move circumferentially along the annular through groove 14, the combustion-supporting gas is conveyed into the annular air distribution pipe 13 through the fan, and enters the mixture layer through the annular through groove 14, the air inlet; the inverted U-shaped annular cover plate 15 is suspended at the bottom of the annular rotating furnace bottom through a steel structure and rotates synchronously with the annular rotating furnace bottom; the annular gas supply pipe and the annular air distribution pipe 13 have the same structure and are arranged concentrically.

Specifically, the annular air distribution pipe 13 is connected with a fan, the annular air distribution pipe 13 is fixed through a support frame 11, an annular through groove 14 is formed in an opening in the upper portion of the annular air distribution pipe 13, an inverted U-shaped annular cover plate 15 is arranged at the top of the annular through groove 14, the inverted U-shaped annular cover plate 15 comprises an annular top plate at the top, annular inner side plates and annular outer side plates at two sides, the annular inner side plates and the annular outer side plates are arranged at two sides of the top end of the annular through groove 14 and are in tight contact with the annular through groove 14, air inlet holes are uniformly distributed in the annular top plate along the circumferential direction, first air inlet branch pipes 5 are connected to the air inlet holes, and the air inlet holes are connected with the air distribution air boxes; in the rotation process of the annular rotating furnace bottom 2, the air distribution bellows 4, the first air inlet branch pipe 5 and the inverted U-shaped annular cover plate 15 rotate together with the annular rotating furnace bottom 2, the annular air distribution pipe is fixed through the supporting frame 11, the inverted U-shaped annular cover plate 15 can rotate on the annular through groove 14, and then combustion-supporting gas in the fan sequentially passes through the annular through groove 14, the air inlet hole, the first air inlet branch pipe 5, the air distribution bellows 4 and the first hole and continuously supplies combustion-supporting gas to the mixed material layer.

It should be noted that, a plurality of annular gas supply pipes and a plurality of annular gas distribution pipes 13 are respectively arranged on two concentric circles with different radiuses, the upper part of each annular gas supply pipe is opened to form an annular through groove, an inverted U-shaped annular cover plate is arranged at the top of the annular through groove, an air inlet hole is arranged on the top plate of the inverted U-shaped annular cover plate along the circumferential direction, and the inner side plate and the outer side plate of the inverted U-shaped annular cover plate are respectively matched with the inner side wall and the outer side wall of the annular through groove, so that the inverted U-shaped annular cover plate can move circumferentially along the annular through groove, gas is delivered into the annular gas supply pipes through a fan and enters a mixture layer through the annular through groove, the air inlet holes of; the inverted U-shaped annular cover plate is suspended at the bottom of the annular rotating furnace bottom through a steel structure and synchronously rotates with the annular rotating furnace bottom.

The application changes the radiation heat supply mode that the traditional rotary hearth furnace is heated by burning high-calorific-value gas by the upper burner, the laying thickness of the mixed material layer in the traditional rotary hearth furnace cannot be too thick, and the mixed material layer cannot be fully combusted if being too thick; the air supply unit is arranged at the bottom of the annular rotary furnace bottom 2, combustion-supporting gas continuously supplies combustion-supporting gas and fuel gas to the mixed material layer through the annular through groove 14, the air inlet hole, the first air inlet branch pipe 5, the air distribution air box 4 and the first hole in sequence (the fuel gas is supplied only in an ignition stage, and the fuel gas is stopped to be supplied after the mixed material in the furnace is ignited by blast air), and then carbon in the mixed material layer can be fully combusted, so that heat is supplied to the rotary hearth furnace; the method changes the radiation heat supply mode of the traditional rotary hearth furnace through the upper burner, and can realize the laying of a thicker mixed material layer on the bottom plate by arranging the air supply unit below the bottom plate, thereby greatly improving the productivity of unit hearth area and having low unit productivity investment; carbon (coal powder) in the mixture is a reducing agent and a heating agent, and heat is supplied by burning carbon in the mixture layer, so that the dependence of a traditional rotary hearth furnace on high-calorific-value coal gas is avoided, and a new path is provided for non-coke smelting.

In order to ensure that the air supply bellows can continuously supply combustion-supporting gas to the mixed material layer when rotating along with the annular rotating furnace bottom 2, the air supply unit comprises a plurality of air inlet pipes, and one end of each air inlet pipe is connected with the air supply bellows 4; the air inlet pipe comprises an air inlet main pipe, a first air inlet branch pipe and a second air inlet branch pipe; the other end of the air inlet pipe is communicated with an annular air distribution pipe 13 through a first air inlet branch pipe and is communicated with an annular gas supply pipe through a second air inlet branch pipe; the main air inlet pipe is a sleeve pipe and comprises an inner pipe and a circular seam pipe, the inner pipe is communicated with one end of the first air inlet branch pipe, and the circular seam pipe is communicated with one end of the second air inlet branch pipe; combustion-supporting gas enters the mixed material layer through the annular air distribution pipe 13, the annular through groove 14, the air inlet hole, the air inlet pipe, the air distribution bellows 4 and the first holes; coal gas enters the mixed material layer through the annular gas supply pipe, the annular through groove 14, the air inlet hole, the air inlet pipe, the air distribution air box 4 and the first hole; the annular gas supply pipe and the annular air distribution pipe are identical in structure and are arranged in the same circle center, namely a plurality of annular gas supply pipes and a plurality of annular air distribution pipes are respectively arranged on two concentric circles with different radiuses.

It should be noted that the fuel gas supplied by the annular fuel gas supply pipe is only used for igniting the mixture together with the combustion-supporting gas, and after the pulverized coal in the mixture is ignited, the fuel gas supply is stopped, but the combustion-supporting gas needs to be supplied continuously.

In order to ensure that the annular air distribution pipe 13 leaks air during air supply, a first annular water tank 17 is arranged on the inner side of the annular through groove 14, a second annular water tank 20 is arranged on the outer side of the annular through groove 14, an annular inner side plate of the inverted U-shaped annular cover plate is inserted into the first annular water tank 17, and an outer side plate of the inverted U-shaped cover plate is inserted into the second annular water tank 20; the first annular water tank 17 and the second annular water tank 20 are used for water sealing the annular air distribution pipe 13.

Specifically, the first annular water tank 17 is arranged on the inner side of the annular through groove 14, the second annular water tank 20 is arranged on the outer side of the annular through groove 14, the first annular water tank 17 and the second annular water tank 20 are independent of each other, the annular inner side plate is inserted into the first annular water tank 17, the annular outer side plate is inserted into the second annular water tank 20, when combustion-supporting gas in the annular air distribution pipe 13 passes through the annular through groove 14, the combustion-supporting gas can only enter the first air inlet branch pipe 5 through the air inlet hole, and the combustion-supporting gas can be prevented from leaking through a gap between the inverted U-shaped annular cover plate 15 and the annular through groove 14 when the annular inner side plate is inserted into the first annular water tank 17 and the annular outer side plate is inserted into.

In order to ensure that the air supply bellows can continuously supply combustion-supporting gas to the mixed material layer when rotating along with the annular rotating furnace bottom 2, the combustion-supporting gas needs to be supplemented into the air distribution bellows, a blower 21 connected with a variable frequency motor is arranged on the outer wall of the air distribution bellows 4, the variable frequency motor takes electricity through a sliding contact line, and the outlet of the blower 21 is communicated with the corresponding air distribution bellows 4 through a pipeline; the blower 21 is used to supply combustion-supporting gas to the air distribution bellows 4.

In order to avoid heat loss of combustion-supporting gas in the annular air distribution pipe 13, the inner side of the annular air distribution pipe 13 is provided with a heat-insulating refractory material 16, and the heat-insulating material can play a role in heat insulation, so that heat loss of the combustion-supporting gas in the annular air distribution pipe 13 is reduced.

In order to ensure the sealing performance between the annular fixed furnace body 1 and the annular rotating furnace bottom 2, the water sealing unit comprises an annular water sealing groove 8, the annular water sealing groove 8 is arranged on the outer side of the bottom plate, a water sealing scraper 7 is arranged on the wall of the annular water sealing groove 8, the bottom of the water sealing groove 8 is communicated with a sludge deposition groove 9, a sewage discharge pipe is arranged in the sludge deposition groove 9, sludge is pumped into the sedimentation tank through a sewage discharge pipe 10 by a sewage pump, and the precipitated water is introduced into the annular water sealing groove 8 again.

In order to ensure continuous feeding to the rotary hearth furnace and uniform laying of mixed materials on a hearth, the rotary hearth furnace further comprises a feeding unit, the feeding unit comprises a conical roller type distributor 18, the conical roller type distributor 18 is arranged on the annular fixed furnace body 1 along the radial direction, the conical roller type distributor 18 comprises a conical roller, the diameter of the conical roller is gradually reduced from the outer side to the inner side of the rotary hearth furnace, a distributing groove is formed in the conical roller, and the distributing groove rotates along with the conical roller; the mixture enters the bottom plate paved by the grate bars through the conical rollers and the distribution grooves, and the roller diameters of the conical rollers are sequentially decreased progressively from outside to inside so as to ensure that the mixture can be uniformly paved on the bottom plate.

In order to further ensure that the mixture can be uniformly laid on the bottom plate, the conical roller is provided with a plurality of material distribution rings which are uniformly distributed along the circumferential direction of the conical roller, and material distribution grooves are uniformly distributed along the circumferential direction of the material distribution rings; the charging amount of the distributing chute corresponds to the area of the hearth.

In order to ensure that the heights of the mixture layers at all positions of the hearth after the mixture is laid are the same, the feeding unit further comprises a scraper, the scraper is fixed in the annular fixed furnace body 1 through a connecting steel plate and is arranged on the rear side of the conical roller type distributor 18, and the scraper is used for scraping the mixture laid on the bottom plate.

In order to avoid the overhigh temperature of the scraper, a water-cooling part is arranged in the scraper, the water-cooling part comprises a cooling water inlet and a cooling water outlet which are arranged at one end of the scraper, cooling water conveying pipes which are arranged in parallel are arranged in the scraper, one end of each cooling water conveying pipe is communicated with the cooling water inlet, and the other end of each cooling water conveying pipe is communicated with the cooling water outlet.

In order to discharge the roasted mixture out of the rotary hearth furnace in time, the discharge unit comprises a material shoveling device 6 and a spiral discharge device, the spiral discharge device is arranged on the annular fixed furnace body 1, and the material shoveling device 6 is used for lifting the furnace burden above the annular retaining wall and then discharging the furnace burden out of the furnace through the fixed spiral discharge device.

Specifically, the discharging unit includes a shoveling device 6 and a spiral discharging device, the spiral discharging device adopts a conventional spiral discharger 12, and the specific structure and working process are not described in detail; the material shoveling device 6 comprises a supporting and shoveling plate, one end of the shoveling plate is hinged with the supporting plate, and the other end of the shoveling plate is used for shoveling materials; when the roasted mixture rotates to the discharge opening, the shoveling plate fixed at the discharge opening gradually lifts the part of the material, when the height of the mixture reaches the set height of the spiral discharger 12, the mixture is discharged into the spiral discharger 12, and finally the roasted mixture is discharged out of the rotary hearth furnace.

In order to ensure the normal rotation of the annular rotating furnace bottom 2, the annular rotating furnace bottom 2 is connected with a furnace bottom driving device 3, the furnace bottom driving device 3 comprises a driving motor, and the driving motor drives a mixed material layer on the annular rotating furnace bottom 2 to rotate for a circle and then discharge materials through a discharging unit.

The flue gas treatment unit comprises a coarse dust collector, a heat exchanger, a bag-type dust collector, a desulfurization tower, a denitration tower, an induced draft fan and a chimney which are communicated with the rotary hearth furnace; a flue gas treatment unit is used for recovering and treating sensible heat, volatilized valuable metals and oxides thereof and dust in the flue gas. Specifically, aiming at short-flow direct reduction of iron ore concentrate or recycling production of metallurgical dust and mud, a single exhaust port is arranged to be connected with a heat exchanger and a dust remover.

Aiming at the direct method production of industrial zinc oxide, the top of a rotary hearth furnace is provided with two exhaust ports, namely a first exhaust port and a second exhaust port, the first exhaust port is used for recovering unqualified zinc oxide powder volatilized earlier, the second exhaust port is used for recovering qualified zinc oxide powder volatilized later, and the first exhaust port and the second exhaust port are connected with a heat exchanger and a dust remover through pipelines; and the flue gas after dust removal is qualified after desulfurization and denitration and then is discharged into the atmosphere through a chimney.

Example 2

The embodiment provides a direct reduction method by using a rotary hearth furnace, which adopts the rotary hearth furnace in the embodiment 1, and when the air distribution wind box 4 is connected with a blower, the direct reduction method by using the rotary hearth furnace comprises the following steps:

step 1, weighing and feeding various materials in a 1 st bin to an nth bin through the 1 st belt scale to a belt conveyor P, conveying the materials to a mixer through the belt conveyor P for mixing, conveying the uniformly mixed materials to a conical roller type distributor 18 of a rotary hearth furnace through the belt conveyor P, and uniformly distributing the materials to a hearth of the rotary hearth furnace through the conical roller type distributor 18;

step 2, combustion-supporting gas enters the mixed material layer through the annular gas distribution pipe 13, the gas distribution air box 4 and the first holes, and meanwhile, gas enters the mixed material layer through the annular gas supply pipe, the gas distribution air box 4 and the first holes; after the blast ignition, the combustion-supporting gas and the fuel gas are ignited, and then the coal powder in the mixed material layer is ignited;

and 3, rotating along with the annular rotating furnace bottom 2, performing direct reduction reaction on related valuable metal oxides and carbon in the mixed material layer, discharging the roasted mixed material out of the rotary hearth furnace through a discharging unit, entering a finished product bin, feeding flue gas generated in the combustion and reaction processes into a coarse dust collector through an exhaust port and a flue, removing relatively large-particle dust, then feeding the dust into a heat exchanger for heat exchange, then feeding the dust into a bag-type dust collector, performing desulfurization and denitrification on the flue gas subjected to fine dust removal treatment, and finally conveying the flue gas to a chimney through a draught fan for discharging.

Compared with the prior art, the technical scheme of the invention at least has the following advantages:

(1) the invention adopts the direct reduction method of the rotary hearth furnace, realizes that the powdery raw material and the coal powder are directly fed into the furnace after being mixed, does not need agglomeration, and simplifies and shortens the process flow.

(2) The coal powder (carbon) in the mixture is a reducing agent and is also a heating agent, so that the dependence of the traditional rotary hearth furnace on high-calorific-value coal gas is eliminated, and a new path is provided for the coke-free smelting.

(3) The carbon combustion heat supply in the mixed material layer changes the radiation heat supply mode of the upper burner of the traditional rotary hearth furnace, can realize the operation of a thick material layer, greatly improves the productivity of unit hearth area, and has low unit productivity investment.

(4) The air burner at the upper part of the hearth of the rotary hearth furnace secondarily oxidizes substances such as coal gas, zinc vapor and the like overflowing from the material layer, generates certain heat to reversely heat the mixed material, and can effectively reduce the primary energy consumption of the rotary hearth furnace.

(5) The method for directly reducing by using the rotary hearth furnace has wide adaptability, the iron concentrate can be used as a raw material to produce directly reduced iron, the industrial zinc oxide can be produced by using an industrial zinc oxide production raw material, and the metallurgical dust and mud can be used as a raw material to realize the recycling of the metallurgical dust and mud.

(6) This application provides the gas for the mixture through the air feed unit when rotary hearth furnace just begins to work, and this part gas and combustion-supporting gas are arranged in making the carbon element in the mixture to be lighted, and the rotary hearth furnace stops to supply the gas in the rotary hearth furnace after being lighted, only supply combustion-supporting gas can, this application regards coal carbon in the mixture as the energy medium, and the low price, the system energy consumption is low, and unit productivity investment is low, has very strong competitiveness.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention should be covered by the present invention.

Claims

1. A rotary hearth furnace for recycling production of metallurgical dust and mud is characterized by comprising a rotary hearth furnace body, a water seal unit and an air supply unit, wherein the rotary hearth furnace body comprises an annular fixed furnace body and an annular rotary furnace bottom arranged at the bottom of the annular fixed furnace body, and the annular fixed furnace body and the annular rotary furnace bottom are sealed through the water seal unit; the bottom end of the annular rotating furnace bottom is provided with a bottom plate provided with a first hole, a mixture is paved on the bottom plate, and the air supply unit is arranged below the bottom plate and used for providing combustion-supporting gas for the mixture;

and the top of the annular fixed furnace body is provided with a single exhaust port, the exhaust port is communicated with the heat exchanger and the dust remover, and the flue gas after dust removal is discharged after being qualified through desulfurization and denitration.

2. The rotary hearth furnace for recycling metallurgical dust and sludge according to claim 1, wherein the annular rotary hearth is connected with a hearth driving device, the hearth driving device comprises a driving motor, and the driving motor drives the mixed material layer on the annular rotary hearth to rotate for a circle and then discharges materials through the discharging unit.

3. The rotary hearth furnace for recycling metallurgical dust and sludge according to claim 2, wherein the bottom plate is laid by using a grate, gaps among the grate and the bottom plate form first holes when the grate is laid, annular retaining walls are arranged on the inner side and the outer side of the annular rotary hearth, and the height of the mixed material layer on the grate is equal to that of the annular retaining walls.

4. The rotary hearth furnace for recycling metallurgical dust and sludge as claimed in claim 3, wherein the discharging unit comprises a material shoveling device and a spiral discharging device, the spiral discharging device is arranged on the annular fixed furnace body, and the material shoveling device is used for lifting the mixture to be above the annular retaining wall at the bottom of the annular rotary furnace and then discharging the mixture out of the furnace through the fixed spiral discharging device.

5. The rotary hearth furnace for recycling metallurgical dust and sludge according to claim 1, wherein the air supply unit comprises a plurality of air distribution bellows arranged below the annular rotary hearth, the air distribution bellows are uniformly distributed along the circumferential direction of the annular rotary hearth, and the air distribution bellows are communicated with the annular rotary hearth and synchronously rotate;

6. The rotary hearth furnace for recycling metallurgical dust and sludge according to claim 5, wherein the air supply unit further comprises an annular gas supply pipe and an annular air distribution pipe connected with a fan, the upper part of the annular air distribution pipe is opened to form an annular through groove, an inverted U-shaped annular cover plate is arranged at the top of the annular through groove, an air inlet hole is formed in the top plate of the inverted U-shaped annular cover plate along the circumferential direction, the inner side plate and the outer side plate of the inverted U-shaped annular cover plate are respectively matched with the inner side wall and the outer side wall of the annular through groove, so that the inverted U-shaped annular cover plate can move circumferentially along the annular through groove, combustion-supporting gas is delivered into the annular air distribution pipe through the fan, and enters the mixture layer through the annular through groove, the air inlet hole of the inverted U-shaped annular cover plate, the air distribution; the inverted U-shaped annular cover plate is suspended at the bottom of the annular rotating furnace bottom through a steel structure and synchronously rotates with the annular rotating furnace bottom;

the annular gas supply pipe and the annular air distribution pipe are identical in structure and concentric in circle.

7. The rotary hearth furnace for recycling metallurgical dust and sludge according to claim 6, wherein the air supply unit further comprises a plurality of air inlet pipes, and one end of each air inlet pipe is connected with the air supply bellows; the air inlet pipe comprises an air inlet main pipe, a first air inlet branch pipe and a second air inlet branch pipe; the other end of the air inlet pipe is communicated with the annular air distribution pipe through the first air inlet branch pipe and is communicated with the annular gas supply pipe through the second air inlet branch pipe; the main air inlet pipe is a sleeve pipe and comprises an inner pipe and an annular seam pipe, the inner pipe is communicated with one end of the first air inlet branch pipe, and the annular seam pipe is communicated with one end of the second air inlet branch pipe;

8. The rotary hearth furnace for recycling metallurgical dust and sludge according to claim 7, wherein the inverted U-shaped annular cover plate comprises an annular top plate, an annular inner side plate and an annular outer side plate, and the annular top plate is provided with an air inlet hole; a first annular water tank is arranged on the inner side of the annular through groove, a second annular water tank is arranged on the outer side of the annular through groove, an annular inner side plate of the inverted U-shaped annular cover plate is inserted into the first annular water tank, and an annular outer side plate of the inverted U-shaped cover plate is inserted into the second annular water tank; the first annular water tank and the second annular water tank are used for sealing air between the annular air distribution pipe and the inverted U-shaped annular cover plate.

9. The rotary hearth furnace for recycling metallurgical dust and sludge according to claim 8, further comprising a feeding unit, wherein the feeding unit comprises a conical roller type distributor, the conical roller type distributor is arranged on the annular fixed furnace body along the radial direction, the conical roller type distributor comprises a conical roller, the roller diameter of the conical roller is gradually reduced from the outer side wall to the inner side wall, the conical roller is provided with a distributing chute, and the distributing chute rotates along with the conical roller;

10. The rotary hearth furnace for recycling metallurgical dust and sludge according to claim 9, wherein the feeding unit further comprises a scraper, the scraper is fixed in the annular fixed furnace body through a connecting steel plate, the scraper is arranged at the rear side of the conical roller type distributor, and the scraper is used for leveling the mixture distributed on the bottom plate.