CN111842877A

CN111842877A - Two-way rotary type flame-isolating heating secondary reduction device for metal powder

Info

Publication number: CN111842877A
Application number: CN202010771798.5A
Authority: CN
Inventors: 唐佳; 高军; 唐竹胜
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-08-04
Filing date: 2020-08-04
Publication date: 2020-10-30

Abstract

The invention discloses a metal powder bidirectional rotary type flame-proof heating secondary reduction device which comprises a cylinder, a cylinder driving and supporting mechanism, a screw shaft driving mechanism and a cylinder heating device, wherein the cylinder is provided with a cylinder body; the screw shaft axially penetrates through the cylinder; a plurality of spiral sheets are longitudinally arranged on the spiral shaft; the cylinder body driving and supporting mechanism drives the cylinder body to rotate; the screw shaft driving mechanism drives the screw shaft to rotate; the rotation direction of the cylinder body is opposite to that of the screw shaft. The device has the advantages of simple equipment, less equipment investment, small occupied area, large scale, energy conservation, extremely high powder heating speed, large filling coefficient, decarburization, tempering, annealing, stress relief and re-reduction functions, internal spiral stirring and reverse rotary type flame-proof heating of rotary conveying materials, and optimization of powder performance and re-reduction.

Description

Two-way rotary type flame-isolating heating secondary reduction device for metal powder

Technical Field

The invention belongs to the field of metallurgical equipment, and particularly relates to a metal powder bidirectional rotary type muffle heating secondary reduction device.

Background

The production of mechanical parts in the world mainly adopts cast iron or cast steel to perform blank casting production, and meanwhile, a small amount of forging, powder metallurgy and other methods are used for preparing the mechanical parts.

The powder metallurgy technology is mature, but cannot produce large parts or metal materials, and the produced parts are expensive; the forging (free forging and die forging) technology is also very mature and stable, but still has the problems of high cost, low productivity and the like when being applied to common parts.

The casting enterprises in China have thousands of families, the casting technology is mature, the application amount is large, but various casting methods all cause environmental pollution, and the state always limits the development and the yield limitation of small-scale casting plants.

In order to meet the requirement of 2025 in China to achieve the world of equipment intelligence building and meet the shortage and contradiction of supply and demand of mechanical part blanks caused by casting limited production, the patentee organically combines a powder metallurgy process technology and a forging process technology to form a new technology between the powder metallurgy and the forging technology, namely a metal powder hot forging process technology. The method is characterized in that reduced iron is processed into powder, various alloy powder or nonmetal powder in a trace amount is added according to the component requirements of part products, and the powder is uniformly mixed and then subjected to medium-frequency induction heating and hot forging press to obtain the blank product of the part product.

The powder metallurgy is generally formed by cold pressing and then sintered at high temperature in atmosphere protection, and the density of the iron-based mechanical parts after cold pressing and sintering is still not more than 7.2t/m²The density can not be increased any more, so the pressing process has strict requirements on reduced iron powder (chemical components and physical properties), primary direct reduced iron powder is required to be subjected to secondary reduction, secondary crushing and grinding, and the content of acid-base insoluble substances, the sphericity degree of iron crystal grains (loose flowability), the loose density and the like are also required to have strict requirements; the pressure requirement of cold pressing is large, and the pressure reaches 700MPa/cm²Therefore, the pressed parts have small specifications, can only produce parts below a few kilograms, and have high production cost, the price of each ton of the parts is between tens of thousands yuan and tens of thousands yuan, and the parts are very expensive.

Since transformation of the metallic phase of the pure metal powder starts to occur at 727 ℃, the surface thereof starts to have a tendency to occur in a liquid phase, that is, sticking starts to occur. Since ordinary metallic iron powder contains C, Si, Mn, S, P and other impurities, the temperature at which liquid phase starts to occur on the surface of ordinary metallic iron powder is further lowered, and therefore, ordinary bulk metallic iron powder is heated to a temperature of less than 700 ℃ while ensuring that the iron powder is kept in a bulk state without agglomeration.

The metal powder heating method is many, and there are various heating methods such as internal combustion type rotary kiln method, external heating type rotary kiln method, mesh belt kiln method, sagger mesh belt kiln method, etc., but these methods are not satisfactory to large-scale production, and the large-scale equipment investment is very large; the kiln has short service life, and the electric appliances and heating elements have large loss, so that the kiln has high failure rate.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a metal powder bidirectional rotary type flame-proof heating device, which solves the problems in metal powder heating. The device has the advantages of simple equipment, less equipment investment, small occupied area, large-scale production, energy conservation, extremely high powder heating and temperature rising speed, and also has the functions of decarburization, tempering, annealing, stress relief and re-reduction, and the internal spiral stirring and the reverse rotary type flame-proof heating of rotary conveying materials can optimize the powder performance and the secondary re-reduction.

The specific technical scheme is as follows:

a metal powder bidirectional rotary type flame-proof heating secondary reduction device comprises a cylinder, a cylinder driving and supporting mechanism, a screw shaft driving mechanism and a cylinder heating device;

the screw shaft axially penetrates through the cylinder; the part of the spiral shaft positioned in the cylinder body is provided with a plurality of circles of spiral sheets around the spiral shaft;

the cylinder body driving and supporting mechanism drives the cylinder body to rotate; the screw shaft driving mechanism drives the screw shaft to rotate; the rotation direction of the cylinder body is opposite to that of the screw shaft.

One end of the cylinder body is a feeding end (kiln tail), and the other end of the cylinder body is a discharging end (kiln head).

The feed end is connected with a feed hopper.

The screw shaft driving mechanism is a motor driving mechanism which is connected with the screw shaft through a coupler and drives the screw shaft to rotate.

The heating temperature of the metal powder of the device is 680-700 ℃, generally is not allowed to exceed 700 ℃, and the heating modes are all muffle type external heating. The heating mode can be resistance heating, gas and fuel flame-isolated external heating; or resistance external heating; or medium frequency induction external heating; or by various methods such as microwave external heating. The outside of the heating layer is preferably attached with an insulating layer.

The material of the cylinder is generally 20g, 304 or 316L, and the cylinder is welded into a cylindrical furnace body, the thickness is generally 18-20 mm, and the cylinder rotates.

The screw shaft and the screw plate are integrated, the material of the screw shaft and the screw plate can be 304L or 316L, and the screw shaft and the screw plate can be welded or cast.

In order to ensure the component requirements and the material uniformity of the prepared blank of the mechanical part, the direct reduced iron block is crushed and ground into fine powder, and then a trace amount of alloy powder or nonmetal powder is added. The raw materials suitable for the chemical components of the product can be obtained by batching according to the index conditions of the components, the powder fineness and the like of the product; some alloy powder (such as ferrosilicon powder, ferromanganese powder, ferronickel powder, ferrochromium powder, ferroboron powder, vanadium powder, molybdenum powder, rare earth powder and the like) can be properly added according to the working environment and condition of the product, and even a small amount or trace amount of non-metal powder (such as graphite powder, silicon carbide powder, alumina powder, zirconia powder and the like) is added, so that the hot-forged product has the effects of wear resistance, corrosion resistance, high temperature resistance and the like. Therefore, it is required that various materials are mixed, uniformly stirred and mixed.

The device of the invention has a principle similar to that of a screw conveyor, metal powder enters a cylinder body through a feeding hopper, and the screw shaft and the screw plate are driven by power to stir and convey. In the heating process, spiral conveying is adopted, and meanwhile, powder materials are mixed and stirred for thousands of times, so that the distribution of various alloy powders is more uniform and stable, the materials are also uniformly heated, the stirring dynamic heating speed of the metal powders is improved by more than one time than that of static heating under the same heating condition, the chemical components of forged and pressed part products are ensured to be uniform, the metallographic structure performance of the products is optimized, the phenomena of air holes, shrinkage cavities, component segregation and the like can not occur like liquid casting and pouring blank parts, and the material filling coefficient can reach 50 percent at most.

Furthermore, the spiral shaft is of a hollow tubular structure, and the part of the spiral shaft positioned in the cylinder body is connected with a plurality of gas injection pipes.

And furthermore, one end of the spiral shaft, which is positioned at the discharge end of the cylinder body, is connected with a gas inlet rotary joint.

The third section of the furnace head of the device is additionally provided with a gas inlet rotary joint which can be filled with N₂Inert gas, or pure H gas₂Strong reducing gas, tail gas can be discharged from the feeding hopper.

The protective gas and the reducing gas can protect the reduced iron powder, prevent the reduced iron powder from being oxidized in the heating process and also can ensure that a small amount of Fe is remained in the reduced iron powder₃O₄Continuation and H₂The content of the metallic iron can be further improved by carrying out the reduction reaction again; the content of C in the reduced iron is generally above 0.5%, and when the heating temperature exceeds 565.5 deg.C, H is added₂For Fe in reduced iron powder₃C, decarburization reaction can occur; when the temperature of steel reaches 680-700 ℃, the reduced iron powder is annealed, and the metal powder with higher carbon content is annealed at 500-550 ℃, so that the internal stress of powder particles caused by crushing, grinding and other processes of reduced iron (powder) blocks is eliminated, meanwhile, the crystal sphericity degree of the reduced iron powder is further optimized, the toughness and loose fluidity of the reduced iron powder are increased, the stability and compactness of a metallographic structure are naturally increased after subsequent forging and pressing part products are naturally increased, and the alloy steel has the functions of secondary reduction, decarburization and tempering. The cold pressure of the reduced iron powder is reduced from about 700MPa to about 450MPa of warm pressure, and the density of the product is reduced from less than 7.2t/m³The temperature and pressure density is increased to be more than or equal to 7.6t/m³Further increasing the strength and application field of the product.

Meanwhile, the air injection pipe also plays a role in raising and stirring the materials, so that the materials are always in a continuous and uniform stirring state on the rotary cylinder of the heating furnace, and the materials are uniformly heated.

Still further, the gas ejector pipe is preferably arranged on the back of the spiral piece, so that full contact between gas and materials is facilitated, and material lifting and stirring are also facilitated.

The gas injection pipe can be arranged corresponding to each turn of the spiral sheet.

The shaft close to one side of the feeding end can be provided with no gas injection pipe; and 1-4 air injection pipes are arranged corresponding to each circle of spiral plate in a high-temperature area close to one third of the length of the discharge end.

Furthermore, both ends of the spiral shaft, which are led out of the cylinder body, are provided with water cooling devices; the water cooling device comprises an automatic water spraying pipe; and a plurality of automatic water spraying pipes are arranged in each group and are connected with the spiral shaft along the circumference. And water retaining flanges are arranged at two ends of the spiral shaft part provided with the automatic water spraying pipe.

The automatic water spraying pipe is matched with a water basin arranged at the lower end of the automatic water spraying pipe for use. The screw axis is when rotatory, automatic trickle pipe also follows the rotation, because the root of automatic trickle pipe is connected around the screw axis, when automatic trickle pipe is rotatory, can take place "waterwheel" effect, when automatic trickle pipe is in the low level, can scoop up the water of basin automatically, when transporting to the high level, the water in the automatic trickle pipe is automatic to flow to the root, sprinkle in the screw axis, play the effect of cooling screw axis, effectively prevented motor drive mechanism, the shaft coupling, kiln tail bearing frame mechanism and kiln head bearing frame mechanism's safety.

And furthermore, two groups of automatic water spraying pipes are respectively arranged at two ends of the spiral shaft, and 4-6 automatic water spraying pipes are arranged in each group. The mouth of the water spraying pipe is preferably bent towards the rotating direction of the water spraying pipe, so that water can be taken conveniently.

Furthermore, the feeding device is designed by utilizing a large space between the cylinder body and the screw shaft; the feeding device comprises a part which is positioned in the cylinder body and surrounds the spiral shaft, and a blanking hole is formed in the part in a semicircular way; the blanking hole is communicated with the feed hopper. The feeding device is beneficial to closed feeding.

Further, the interface of the cylinder body and the screw shaft is sealed by sealing high-temperature rock wool. When the feed end sets up feeding device, sealed high temperature rock wool can set up between barrel and feeding device.

Further, the cylinder heating device is characterized in that a heating layer is arranged on the outer wall of the cylinder, and preferably an outer induction heating coil is arranged on the outer wall of the cylinder.

And furthermore, an outer heat insulation sleeve is arranged outside the heating layer. A heat insulation sleeve can be arranged between the external induction heating coil and the cylinder body.

Further, the cylinder driving and supporting mechanism comprises cylinder supporting rings positioned at two ends and the middle part of the cylinder, and supporting wheels are arranged at the bottom of the cylinder supporting rings; riding wheels at two ends of the cylinder are driving riding wheels; the riding wheel positioned in the middle of the cylinder body is a supporting riding wheel.

Furthermore, a kiln head bearing seat mechanism and a kiln tail bearing seat mechanism are respectively arranged at two ends of the spiral shaft.

Further, a kiln head discharging cover is arranged at the discharging end of the cylinder body, and a blanking hole is formed in the cylinder body corresponding to the kiln head discharging cover; the bottom of the kiln head discharging cover is provided with a discharging pipe.

The invention has the following beneficial effects:

1. strong raw material adaptability, large heating capacity, low equipment investment and small occupied area.

The method is suitable for heating various 40-400 mesh powder, TFe 90-99% direct reduced iron powder, regenerated metal iron and metal alloy powder, and can also be used for heating metal particle raw materials containing particle steel of 0-10 mm.

According to the heating device with the effective diameter phi of 450mm, the maximum material filling coefficient can reach 50%, and the annual capacity for heating metal iron powder can reach more than 5 ten thousand tons.

The length of the heating device is not more than 5m, the diameter phi of the heating device is 450mm, the occupied area is only within 2m, and the occupied area is only 10m²Left and right; the maximum investment of production line equipment can be controlled within 50 ten thousand yuan.

2. The heating mode is diversified.

The heating mode can be gas or fuel flame-isolated external heating; or resistance external heating; or medium frequency induction external heating; or by various methods such as microwave external heating.

3. The forged and pressed part blank has less machining allowance and no segregation of alloy components.

The device mixes and stirs powder materials thousands of times while adopting spiral conveying in the heating process, so that the distribution of various alloy powders is more uniform and stable, the materials are uniformly heated, the chemical composition of forged and pressed part products is ensured to be uniform, the metallographic structure performance of the products is optimized, and the phenomena of air holes, shrinkage cavities, component segregation and the like can not occur like liquid-state cast and poured blank parts; the metal powder forging is in a die forging pressing mode, so that the machining allowance of the product is small.

4. Has the functions of decarburization and annealing.

The third section of the furnace head of the device is additionally provided with a gas inlet rotary joint which can be filled with N₂Inert gas, or pure H gas₂Strong reducing gas, which can protect the reduced iron powder and prevent the oxidation phenomenon during the heating process, and can also make a small amount of Fe remained in the reduced iron powder₃O₄Continuation and H₂The content of the metallic iron can be further improved by carrying out the reduction reaction again; the internal stress of powder particles caused by the procedures of crushing, grinding and the like of the reduced iron block is eliminated; meanwhile, the crystal sphericity degree of the reduced iron powder is further optimized, the toughness and loose fluidity of the reduced iron powder are increased, and the stability and compactness of a metallographic structure after a subsequent forged part product is naturally increased.

In addition, the stirring dynamic heating speed of the metal powder is more than doubled compared with the static heating speed under the same heating condition.

The cold pressure of the reduced iron powder is reduced from about 700MPa to about 450MPa of warm pressure, and the density of the product is reduced from less than 7.2t/m³The temperature and pressure density is increased to be more than or equal to 7.6t/m³Further increasing the strength and application field of the product.

5. Has the function of re-reduction.

This device can replace powder metallurgy's the first time reduced iron powder completely, carries out hydrogen secondary reduction's guipure reduction kiln again, and moreover, the material is abundant with hydrogen contact, and the reduction is abundant, and the reduction product still is the likepowder, need not to carry on secondary crushing, crocus again, and the performance of the reduced iron powder of secondary reduction optimizes phase structure, reaches the requirement of metallurgical powder casting die, has reduced the physical requirement to the first time reduced iron powder, has secondary reduction, decarbonization and quenching and tempering function.

And the parts can be directly subjected to warm pressing and modeling, so that the parts subjected to subsequent primary forging and pressing or secondary forging and pressing have higher density and higher strength.

6. The materials are heated evenly

The heating temperature of the metal powder of the device is 680-700 ℃, generally is not allowed to exceed 700 ℃, and the heating modes are all muffle type external heating.

The flight that adopts in this device carries out material mixing and material transport, simultaneously, the jet-propelled pipe of back welding of the epaxial flight, protective gas or reducing gas that gaseous access rotary joint got into are added from gas, many jet-propelled pipes on the rethread screw axis, directly send into protective gas or reducing gas in the material deep layer, make protective gas or reducing gas, can fully contact with the material, and simultaneously, also carry out the raising and stirring effect to the material, also make the material be in succession on the rotary barrel of heating furnace all the time, even stirring state, also make the material heating even.

The thickness of the rotary cylinder is generally more than 18-20 mm, and during heating, the rotary cylinder and the spiral shaft jointly form a heat accumulator, so that the obtained heat can be timely conducted to metal powder in the moving process of the kiln device. Simultaneously, the rotatory direction of flight and gyration barrel rotation direction, the two direction of operation just in time are opposite, make the continuous transform heating position of gyration barrel, have prevented effectively that the gyration barrel from being in a fixed position for a long time, prevent that the material of gyration barrel from taking place phase transition and bending, simultaneously, also help the material to do stirring work, more utilize the stove interior material to be heated evenly.

7. And water cooling devices are arranged at two ends of the heating furnace.

In order to protect components such as a motor driving mechanism, a speed reducer bearing and the like, two ends of the heating furnace device are respectively provided with a kiln tail water cooling device and a kiln head water cooling device, so that the heating furnace device can automatically spray water for cooling, effectively protect the screw shaft and the driving mechanism and the bearing seat mechanism at the two ends of the screw shaft, and prevent the screw shaft and the driving mechanism and the bearing seat mechanism from being damaged due to overheating.

8. Energy conservation and environmental protection.

The induction heating is adopted, so that the heat efficiency can reach 80% at most, and meanwhile, the medium-frequency induction heating temperature is lower, no smoke is discharged, so that the energy conservation and emission reduction are realized, the ecological environment is protected, the zero discharge is realized, and the casting method without smoke is formed.

Drawings

FIG. 1 is a schematic view of the apparatus of the present invention in example 1;

FIG. 2 is a schematic view taken along the line A-A of FIG. 1;

FIG. 3 is a schematic view of FIG. 1 taken along the direction B-B;

FIG. 4 is a schematic view in the direction C-C of FIG. 1;

FIG. 5 is a schematic view in the direction D-D of FIG. 1;

FIG. 6 is a schematic view taken along the line E-E in FIG. 1;

FIG. 7 is a schematic view in the direction F-F of FIG. 1;

FIG. 8 is a schematic view taken along the direction H-H in FIG. 1;

in the figure, 1, a motor driving mechanism; 2. a coupling; 3. a kiln tail bearing seat mechanism; 4. a kiln tail water cooling device; 5. a water retaining flange; 6. an automatic water spraying pipe; 7. a basin; 8. a metal powder; 9. feeding into a hopper; 10. a kiln tail cylinder body supporting ring mechanism; 11. a kiln tail pulley driving mechanism; 12. a barrel; 13. a spiral sheet; 14. a gas ejector tube; 15. an external induction heating coil; 16. an outer insulating sleeve; 17. a middle cylinder support ring mechanism; 18. a middle riding wheel supporting mechanism; 19. a screw shaft; 20. a kiln head discharging cover; 21. a kiln head cylinder support ring mechanism; 22. a kiln head supporting wheel driving mechanism; 24. a kiln head bearing seat mechanism; 25. a hot metal powder; 26. a feeding device; 27. sealing the high-temperature rock wool; 28. a blanking hole; 29. the supporting ring prevents the expansion and the lacing wire; 30. a discharge pipe; 31. a barrel kiln head blanking hole; 32. a cylinder kiln head sealing plate; 33. introducing gas into the rotary joint; 34. charging and sealing;

in fig. 3 to 8, the upper end arrow represents the rotation direction of the screw shaft, and the lower end arrow represents the rotation direction of the cylinder.

Detailed Description

The principles and features of this invention are described below in conjunction with examples, which are set forth to illustrate, but are not to be construed to limit the scope of the invention.

Example 1

A metal powder bidirectional rotary type flame-proof heating secondary reduction device is shown in figures 1-8 and comprises a cylinder body 12, a cylinder body driving and supporting mechanism, a screw shaft 19 and a cylinder body heating device of the screw shaft driving mechanism.

The cylinder 12 is a welded cylindrical furnace body, has the thickness of 18-20 mm and performs rotary motion.

One end of the cylinder 12 is a feeding end (kiln tail), the other end is a discharging end (kiln head), the feeding end is connected with the feeding hopper 9, and the highest material filling coefficient can reach 50%.

The cylinder heating device is an external induction heating coil 15 arranged on the outer wall of the cylinder 12, and an external heat-insulating sleeve 16 is arranged outside the external induction heating coil 15; a thermal insulation sleeve 16 is also arranged between the outer induction heating coil 15 and the cylinder body.

The screw shaft 19 axially penetrates through the cylinder 12; the part of the screw shaft 19 positioned in the cylinder 12 is provided with a plurality of screw sheets 13; the screw shaft 19 and the screw sheet 13 are integrated, and the screw shaft 19 is of a hollow tubular structure; the pitch of the spiral sheet 13 is 150-300 mm, and the rotating speed is 5-10 r/min.

The cylinder 12 rotates in the opposite direction to the screw shaft 19.

The screw shaft 19 and the screw plate 13 have the functions of stirring and conveying;

one end of the spiral shaft 19 corresponding to the discharge end of the cylinder 12 is connected with a gas inlet rotary joint 33, and N can be introduced according to requirements₂Inert gas, or H gas₂Reducing gas is used; the back of the spiral sheet 13 on each circle of the spiral shaft 19 is welded with the gas injection pipe 14, the gas moves along the spiral shaft 19, is sprayed out from the gas injection pipe 14 and can be directly sent into the heated powder material, and the tail gas can be discharged from the feeding hopper 9; the gas injection pipe 14 not only sends gas into the metal powder 8, but also plays a role in material raising and stirring, so that the metal powder 8 in the cylinder body 1 is uniformly stirred; the tail gas can be discharged from the feed hopper 9.

The cylinder driving and supporting mechanism drives the cylinder 12 to rotate; the screw shaft driving mechanism drives the screw shaft 19 to rotate;

the screw shaft driving mechanism is characterized in that the motor driving mechanism 1 is connected with the screw shaft 19 through the coupler 2 and drives the screw shaft to rotate;

the cylinder driving and supporting mechanism of the screw shaft driving mechanism comprises a kiln tail cylinder ring supporting mechanism 10, a kiln tail ring supporting mechanism 11, a kiln head cylinder ring supporting mechanism 21 and a kiln head supporting wheel driving mechanism 22 which are positioned at two ends of a cylinder; a middle cylinder body supporting ring mechanism 17 and a middle supporting wheel supporting mechanism 18 which are positioned in the middle of the cylinder body; the kiln tail riding wheel driving mechanism 11 and the kiln head riding wheel driving mechanism 22 are active driving mechanisms, and the middle riding wheel supporting mechanism 18 is a mechanism for passively supporting the cylinder body 12, so that the middle of the cylinder body 12 is prevented from bending and deforming; the cylinder 12 is driven by friction to rotate by a kiln tail cylinder supporting ring mechanism 10 and a kiln head cylinder supporting ring mechanism 21 at a kiln tail supporting wheel driving mechanism 11 and a kiln head supporting wheel driving mechanism 22, and the rotating speed is 1-2 r/min; a supporting ring anti-expansion lacing wire 29 is arranged between the supporting ring and the cylinder body 12;

the two ends of the screw shaft are respectively provided with a kiln head bearing seat mechanism 24 and a kiln tail bearing seat mechanism 3.

The invention also comprises a feeding and discharging device; the feeding device 26 is arranged at the feeding end of the barrel 12, the feeding device 26 comprises a part which is positioned in the barrel 12 and surrounds the spiral shaft 19, and a blanking hole 28 is arranged on the part in a semicircular way; the blanking hole 28 is communicated with the feeding hopper 9;

the discharge end of the cylinder 12 is provided with a plurality of cylinder kiln head blanking holes 31 which are hermetically wrapped by a kiln head discharging cover 20, and the sealing of the kiln head discharging cover 20 and the cylinder 12 adopts a fish scale sealing method; the bottom of the kiln head discharging cover 20 is provided with a discharging pipe 30; the hot metal powder 25 enters the kiln head discharging cover 20 through the barrel kiln head discharging hole 31 and is discharged through the discharging pipe 30.

The invention also comprises an automatic water cooling device; the two ends of the screw shaft 19 are respectively provided with a kiln tail water cooling device 4 and a kiln head water cooling device 23, and the lower parts of the screw shaft are provided with water basins 7;

the kiln tail water cooling device 4 and the kiln head water cooling device 23 consist of a water retaining flange 5 and an automatic water spraying pipe 6; two groups of automatic water spraying pipes 6 are respectively arranged at two ends of the spiral shaft 19, and 4 automatic water spraying pipes 6 in each group are welded on the outer wall of the spiral shaft 19 along the circumference; the water retaining flanges 5 are arranged at two ends of the spiral shaft part where the automatic water spraying pipe 6 is arranged;

the water retaining flange 5 is arranged to prevent water from covering towards two sides; screw axis 19 is when rotatory, automatic trickle pipe 6 also follows rotatoryly, because the root of automatic trickle pipe 6 is spot welding at screw axis 19, when automatic trickle pipe 6 is rotatory, can take place "waterwheel" effect, when automatic trickle pipe 6 is in the low level, can scoop up the water of basin 7 automatically, when transporting the high level, the water in the automatic trickle pipe 6 automatically flows to the root, spill in screw axis 19, play the effect of cooling screw axis 19, motor drive mechanism 1 has effectively been guaranteed, shaft coupling 2, kiln tail bearing frame mechanism 3 and kiln head bearing frame mechanism 24's safety.

The invention also includes a sealing device; the cylinder 12 and the screw shaft 19 rotate in opposite directions, and the contact positions of the two ends of the cylinder are required to be sealed; the sealing of the screw shaft is simple, and because the positive pressure of the protective gas or the reducing gas in the cylinder body 12 is very low, a layer of sealing high-temperature rock wool 27 with the thickness of 20-30 mm is wrapped on the screw shaft 19 at the interface of the cylinder body 12 and the screw shaft 19 and is sealed by friction; the sealed high-temperature rock wool 27 at the feeding end is arranged between the barrel 12 and the feeding device 26;

towards one end of the kiln tail, a feeding seal 34 is arranged between the feeding device 26 and the spiral shaft 19 in the same way;

the tail end of the cylinder 12 at the discharge end is provided with a cylinder kiln head sealing plate 32, and sealing high-temperature rock wool 27 is arranged between the sealing plate 32 and the spiral shaft 19.

When the device is used, the cylinder body 12 is heated, and the water cooling device is started; conveying metal powder 8 from a feeding hopper 9 into a cylinder 12, and stirring and conveying the materials under the driving of a spiral shaft 19 and a spiral sheet 13; n is fed from the gas feed rotary joint 33 as required₂Inert gas, or pure H₂Strong reducing gas to protect the reduced iron powder and prevent oxidation during heating, and small amount of Fe remains in the reduced iron powder₃O₄Continuation and H₂And carrying out re-reduction reaction to further improve the content of the metallic iron. The hot metal powder 25 enters the kiln head discharging cover 20 through the barrel kiln head discharging hole 31 and is discharged through the discharging pipe 30.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. The metal powder bidirectional rotary type flame-proof heating secondary reduction device is characterized by comprising a cylinder body (12), a cylinder body driving and supporting mechanism, a screw shaft (19), a screw shaft driving mechanism and a cylinder body heating device;

the screw shaft (19) axially penetrates through the cylinder body (12); a plurality of turns of helical fins (13) are arranged around the helical shaft (19);

the cylinder driving and supporting mechanism drives the cylinder (12) to rotate; the screw shaft driving mechanism drives the screw shaft (19) to rotate; the cylinder (12) and the screw shaft (19) rotate in opposite directions.

2. The metal powder bidirectional rotary type muffle heating secondary reduction device according to claim 1, wherein the screw shaft (19) is a hollow tubular structure, and the part of the screw shaft located inside the cylinder (12) is connected with a plurality of gas injection pipes (14).

3. The metal powder bidirectional rotary type muffle heating secondary reduction device according to claim 2, wherein the screw shaft (19) is connected with a gas inlet rotary joint (33) at one end of the discharge end of the cylinder (12).

4. The metal powder bidirectional rotary type muffle heating secondary reduction device as claimed in any one of claims 1 to 3, wherein water cooling devices are arranged at both ends of the spiral shaft (19) which passes through the cylinder (12); the water cooling device comprises an automatic water spraying pipe (6); each group of automatic water spraying pipes (6) is provided with a plurality of automatic water spraying pipes which are connected with the outer wall of the spiral shaft (19) along the circumference; two ends of the part of the screw shaft (19) provided with the automatic water spraying pipe (6) are provided with water retaining flanges (5).

5. The metal powder bidirectional rotary type muffle heating secondary reduction device according to claim 4, wherein two groups of automatic water spraying pipes (6) are respectively arranged at two ends of the spiral shaft (19), and each group of automatic water spraying pipes (6) is 4-6.

6. The metal powder bidirectional rotary type muffle heating secondary reduction device according to any one of claims 1 to 3, further comprising a feeding device (26); the feeding device (26) comprises a part which is positioned in the barrel body (12) and surrounds the screw shaft (19), and the upper part of the part is provided with a blanking hole (28); the blanking hole (28) is communicated with the feeding hopper (9).

7. The metal powder bidirectional rotary type muffle heating secondary reduction device according to any one of claims 1 to 3, wherein the interface between the cylinder (12) and the screw shaft (19) is sealed by sealing high-temperature rock wool (27).

8. The metal powder bidirectional rotary type muffle heating secondary reduction device according to any one of claims 1 to 3, wherein the cylinder heating device is an external induction heating coil (15) arranged on the outer wall of the cylinder (12).

9. The metal powder bidirectional rotary type muffle heating device according to claim 8, wherein an outer insulating sleeve (16) is arranged outside the outer induction heating coil (15).

10. The metal powder bidirectional rotary type muffle heating device according to any one of claims 1 to 3, wherein the cylinder driving and supporting mechanism comprises cylinder supporting rings positioned at two ends and in the middle of the cylinder (12), and supporting wheels are arranged at the bottom of the cylinder supporting rings; riding wheels at two ends of the cylinder body (12) are driving riding wheels; the riding wheel positioned in the middle of the cylinder body (12) is a supporting riding wheel.