CN113322362A - Self-heating balance laterite reduction method - Google Patents
Self-heating balance laterite reduction method Download PDFInfo
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- CN113322362A CN113322362A CN202110426750.5A CN202110426750A CN113322362A CN 113322362 A CN113322362 A CN 113322362A CN 202110426750 A CN202110426750 A CN 202110426750A CN 113322362 A CN113322362 A CN 113322362A
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0066—Preliminary conditioning of the solid carbonaceous reductant
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/02—Making spongy iron or liquid steel, by direct processes in shaft furnaces
Abstract
The invention belongs to the technical field of nonferrous smelting, and particularly relates to a laterite self-heating balance reduction method. According to the reduction process, coal is used as a reducing agent, on one hand, crystal water carried by laterite is evaporated at high temperature and then reacts with coal to generate coal gas, on the other hand, the reduction process also generates the coal gas and decomposed volatile components in the coal, the mixed coal gas is led out at high temperature and returns to a combustion chamber to be combusted as a heat source, extra fuels such as coal gas and the like are not needed, the process is simple, the energy consumption is low, and the energy is saved and the environment is protected. The adopted coal is low-cost low-grade bituminous coal, self-heating reduction is realized, energy is saved, the environment is protected, and the production cost is low. The direct reduction shaft furnace can realize self-heating direct reduction, does not need or only needs a small amount of additional fuel gas, and can effectively reduce energy consumption and production cost.
Description
Technical Field
The invention belongs to the technical field of nonferrous smelting, and particularly relates to a laterite self-heating balance reduction method.
Background
At present, the front end of laterite smelting mainly adopts a rotary kiln process, and the rotary kiln process has the advantages of long process flow, low reduction temperature, low metallization rate, high reducing agent consumption, easy ring formation of the rotary kiln, low operation rate and small scale.
The traditional direct reduction process needs external heat supply to realize the reduction function, heat is supplied through solid or gas fuel, the process is complicated, and the energy utilization efficiency is low.
A plurality of processes using coal as fuel or reducing agent have more heavy tar in the coal, more light tar in lignite, and the tar yield of one ton of bituminous coal of 20-60 kg/Nm3About 0.01 to 0.02kg/Nm in dry gas3. As the temperature of the coal gas is reduced, the tar steam is condensed into tar mist which is condensed and combined with dust in the coal gasDeposition, equipment and pipelines affect the transportation of coal gas, and the coal gas needs to be evolved to remove tar and dust.
There is therefore a need to devise a laterite autothermal equilibrium reduction process to overcome the above problems.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a laterite self-heating balance reduction process, wherein laterite containing crystal water is directly added into a reduction furnace, on one hand, the crystal water evaporated in a high-temperature region can react with coal to generate water gas, on the other hand, the coal gas generated in the reduction process and the volatile component decomposed by the coal are mixed gas which is in a gaseous state in a high-temperature section and can be directly led out by an induced draft fan for self-circulation use, so that the crystal water in the laterite and the tar of the coal are directly utilized, the composite functions of gas making, reduction and heat supply are completed, and the purposes of simple process, short flow, low energy consumption, energy conservation, environmental protection and production cost reduction are achieved.
The invention provides a reduction shaft furnace for laterite smelting, which comprises a combustion chamber (2) and at least one reduction chamber (1), wherein the reduction chamber (1) is of a vertically arranged cylindrical structure, and a plurality of reduction chambers (1) can be arranged in the combustion chamber (2) in an array manner; the top of the reduction chamber (1) is provided with a feed inlet, and the bottom of the reduction chamber (1) is provided with a discharge outlet; the upper portion of reducing chamber (1) is equipped with gaseous eduction port, combustor (2) are equipped with outer gas inlet, combustion air inlet and a plurality of reducing chamber gas inlet, and is a plurality of reducing chamber gas inlet ring is located combustor (2) are located the ascending middle section part of vertical side, and every reducing chamber gas inlet passes through gas pipe and at least one the gaseous eduction port intercommunication, and outer gas inlet that supplies passes through the gas pipeline and is connected with outer gas supply source, and combustion air inlet passes through combustion air pipeline and is connected with the air-blower.
Further, since the combustion chamber 2 and the reduction chamber 1 are arranged in contact with each other in this order, the gas outlet of the reduction chamber 1, the external gas supply inlet of the combustion chamber 2, the reduction chamber gas inlet, and the combustion air inlet may be provided on the side surfaces of the corresponding furnace bodies (i.e., not on the contact surfaces with the adjacent reduction chamber 1 or combustion chamber 2), respectively. As the external gas supply and the gas of the reduction chamber are introduced into the middle part of the combustion chamber 2 for combustion, a middle temperature section, a high temperature section and a low temperature section are sequentially formed in the combustion chamber 2 from top to bottom, and a preheating section, a reduction section and a cooling section are correspondingly sequentially formed in each reduction chamber 1 from top to bottom.
Furthermore, in order to improve the cooling capacity of the cooling section, a cooling mechanism can be arranged in the cooling section, for example, the cooling mode of the cooling section of the existing shaft furnace is adopted, namely a cooling air injection structure is arranged at the lower end of the cooling section, and a cooling air collection structure is arranged at the upper end of the cooling section; or the following structure is adopted: the cooling mechanism comprises cooling water channels arranged in furnace walls 3 of the reduction chambers in corresponding cooling sections, inlets of the cooling water channels are communicated with a cooling water supply pipe, outlets of the cooling water channels are communicated with a cooling water return pipe, and the furnace walls 3 of the reduction chambers in the cooling sections form cooling walls for cooling reduction products; the cooling water channels may be arranged in serpentine fashion in the corresponding reduction chamber furnace walls 3 to increase the heat exchange area.
The reduction shaft furnace is a fixed hearth, and a large number of large and complex transmission devices of the direct reduction shaft furnace are cancelled; the reduction zone is separated from the combustion zone, so that the atmosphere in the reduction furnace can be controlled, the reduced sponge iron is prevented from being secondarily oxidized, and high-quality sponge iron can be produced; the reduction speed can be controlled by adjusting the blanking speed, and the reduction degree of the product is controllable. In addition, because the reduction chambers 1 and the combustion chambers 2 are arranged alternately in sequence, the number of the corresponding reduction chambers 1 and the number of the corresponding combustion chambers 2 can be increased in sequence according to the requirement of production scale, and the large-scale production is realized. According to the shaft furnace, the gas outlet is formed in the upper part of the reduction chamber 1, combustible gas such as coal gas generated in the reduction process can be filled into the middle of the combustion chamber 2 for combustion, and heat is provided for the reduction chamber 1, so that the shaft furnace can realize self-heating direct reduction, a small amount of extra fuel gas is not needed or only needed, and the energy consumption and the production cost can be effectively reduced.
The invention also provides a laterite self-heating equilibrium reduction method, which comprises the following steps:
raw material preparation: mixing the dried laterite containing the internal crystal water with a reducing agent, wherein the reducing agent is pulverized coal, and the coal contains 65-75% of fixed carbon and 20-35% of volatile components by mass percent;
a material distribution step: distributing lump coal and the pellets into the reduction chambers, wherein the molar ratio of carbon to oxygen in the raw materials in each reduction chamber is 0.6-1.2;
a direct reduction step: introducing external gas supply into each combustion chamber to burn and bake the furnace, wherein raw materials in each reduction chamber are subjected to reduction reaction in the furnace baking process, coal gas generated by the reduction reaction and volatile matters generated by thermal decomposition in the coal are led out from each reduction chamber and uniformly introduced into each combustion chamber to burn, and when the coal gas and the volatile matters introduced into the combustion chambers burn and can meet the heat requirement of the reduction reaction, stopping gas supply;
a discharging step: discharging the produced high-metallization-rate products and semi-coke from the bottom of each reduction chamber, and separating and recovering the products.
Furthermore, the coal gas generated by each reduction chamber and the volatile components generated by thermal decomposition in the coal are uniformly introduced into the combustion chamber for combustion at a high-temperature section by an induced draft fan.
Further, in the step of direct reduction, the composite coal gas generated in each reduction chamber is introduced into the middle-lower section of the combustion chamber in the vertical direction by a draught fan to be partially combusted, and a preheating section, a reduction section and a cooling section are sequentially formed in each reduction chamber from top to bottom.
Further, in the direct reduction step, the reduction reaction temperature is within the range of 900-1150 ℃.
Further, in the raw material preparation step, the granularity of the coal and the granularity of the laterite are both less than or equal to 30 mm.
Further, the pulverization rate of the laterite is not limited, and the crystal water is not limited.
Further, in the distributing step, the coal and the ore are both mixed.
Further, in the discharging step, the bottom of each reduction chamber is discharged and simultaneously fed from the top of each reduction chamber, and the discharging speed of each reduction chamber is controlled to be matched with the feeding speed of each reduction chamber, so that continuous operation is realized.
Further, the semi coke discharged from the discharging material can be recycled.
Further, the external supply gas is natural gas or coal gas and the like.
The principle of the direct reduction process of the invention is as follows:
volatile components in the coal are decomposed under the heating condition, C in the coal reacts with iron oxide on the surfaces of the contacted pellets to generate reducing gas CO, the CO and the iron oxide in the pellets undergo a reduction reaction to generate metallic iron and CO2, CO2 and carbon in the coal undergo a gasification reaction to generate CO, and the CO enters the pellets to reduce the iron oxide to generate CO 2; by cycling in this way, the whole reaction can be explained by an unreacted nuclear model, and the driving force of adsorption and desorption of CO and CO2 in the pellets is the concentration gradient. Coal gas (CO) generated by reduction reaction and volatile matter (mainly comprising H) generated by thermal decomposition in coal2、CmHn、CO、CO2) Is introduced into the combustion chamber 2 where the combustible gas combusts exothermically to provide heat to the reduction chamber 1. Under ideal conditions, when the molar ratio of carbon to oxygen is 1, the carbon and oxygen can fully react to generate CO completely; however, considering the insufficiency of carbon-oxygen combination, the molar ratio of carbon to oxygen is set to be more than 1, and the content of volatile components in coal is more than 20%, so that sufficient reducing atmosphere and the amount of coal gas can be ensured, and the full-coal-based self-heating direct reduction is realized.
The gas and volatile components generated in each reduction chamber 1 need to be uniformly distributed to each region in the combustion chamber 2 for combustion, so as to ensure that the temperature of each region at the same height position in the combustion chamber 2 is approximately the same, so as to ensure that the reduction reaction temperature of each reduction chamber 1 is uniform, and further ensure the homogeneity of the reduction product. In order to achieve the purpose, a plurality of reducing chamber gas inlets are formed in the combustion chamber 2, the reducing chamber gas inlets are uniformly and annularly arranged on the middle section part of the combustion chamber 2 in the vertical direction, and each reducing chamber gas inlet is communicated with at least one gas leading-out opening through a gas pipe. In order to improve the combustion uniformity, the gas leading-out ports of the reduction chambers 1 are connected into the same gas collecting pipe, a gas distributor is arranged at the outlet end of the gas collecting pipe, and the gas inlets of the reduction chambers of the combustion chamber 2 are communicated with the gas distributor.
The invention has the following beneficial effects:
according to the reduction process, coal is used as a reducing agent, on one hand, crystal water carried by laterite is evaporated at high temperature and then reacts with coal to generate coal gas, on the other hand, the reduction process also generates the coal gas and decomposed volatile components in the coal, the mixed coal gas is led out at high temperature and returns to a combustion chamber to be combusted as a heat source, extra fuels such as coal gas and the like are not needed, the process is simple, the energy consumption is low, and the energy is saved and the environment is protected. The adopted coal is low-cost low-grade bituminous coal, self-heating reduction is realized, energy is saved, the environment is protected, and the production cost is low. The direct reduction shaft furnace can realize self-heating direct reduction, does not need or only needs a small amount of additional fuel gas, and can effectively reduce energy consumption and production cost.
Drawings
FIG. 1 is a schematic structural diagram of a laterite self-heating equilibrium reduction shaft furnace provided by the invention;
FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;
FIG. 3 is a top view of the present invention;
FIG. 4 is a flow diagram of a laterite autothermal equilibrium reduction process provided by the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example one
Referring to fig. 1-4, the embodiment of the present invention provides a direct reduction process of a low-cost laterite autothermal equilibrium reduction shaft furnace, wherein the reduction furnace is a shaft furnace, the shaft furnace comprises at least one reduction chamber 1, and each reduction chamber 1 is supplied with heat by at least one combustion chamber 2.
The process comprises the following steps:
raw material preparation: after the laterite is dried by external water, the reducing agent is bituminous coal, wherein the content of fixed carbon in the coal is 65-75% by mass percent, and the content of volatile components in the coal is 20-35%. Wherein, the particle size distribution of the coal and the pellets has no requirement, and the larger particle size needs to be crushed and controlled within 30 mm.
A material distribution step: distributing lump coal and the pellets into the reduction chambers 1, wherein the molar ratio of carbon to oxygen in the raw materials in each reduction chamber 1 is 0.8. The coal and the ore are preferably mixed and distributed so as to achieve the aim of uniform reaction and improve the homogeneity of the reduction product.
A direct reduction step: and external gas supply is introduced into each combustion chamber 2 to burn and bake the furnace, raw materials in each reduction chamber 1 are subjected to reduction reaction in the furnace baking process, coal gas generated by the reduction reaction and volatile components generated by thermal decomposition in the coal are led out from each reduction chamber 1 by a high-temperature coal gas induced draft fan 4 and are uniformly fed into each combustion chamber 2 through a burner 3 to be burnt, and when the combustion of the coal gas and the volatile components introduced into the combustion chambers 2 can meet the heat requirement of the reduction reaction, the gas supply is stopped. Wherein, the external supply gas can adopt natural gas or coal gas; the reduction reaction temperature is in the range of 900-1150 ℃, preferably 1100 ℃. The time for stopping gas supply can be controlled by operators in the actual production process, factors such as the combustion amount of externally supplied gas, the calorific value which can be generated by combustion, the content of volatile components in coal, the granularity of ore and coal and the like need to be considered, and a period of time can be delayed from the theoretical time so as to ensure that enough combustible gas is in the combustion chamber 2.
A discharging step: the produced product and semi coke are discharged from the bottom of each reduction chamber 1 and separated and recovered. Further, in this step, the bottom of each reduction chamber 1 is discharged and simultaneously the top of each reduction chamber 1 is charged, and the discharge speed of each reduction chamber 1 is controlled to be matched with the charging speed thereof so as to form continuous operation. By controlling the discharging speed, the retention time of the raw materials in the reduction chamber 1 is controllable, so that the reduction degree of the product is controllable, and the product with the required grade is obtained.
The shaft furnace described in this embodiment adopts the following structure: the shaft furnace comprises a combustion chamber 2, each reduction chamber 1 is of a vertically arranged cylindrical structure, and each reduction chamber 1 is arranged in the combustion chamber 2 in an array manner; the coal gas generated by each reduction chamber 1 and the volatile components generated by the thermal decomposition of the coal are uniformly introduced into the combustion chamber 2 for combustion. Each reduction chamber 1 is separated from the combustion chamber 2 by a reduction chamber furnace wall 3. Namely, the direct reduction process adopts a fixed hearth, and one combustion chamber 2 supplies heat to each reduction chamber 1, so that a large and complicated transmission device of most direct reduction furnaces is eliminated; the reduction zone is separated from the combustion zone, so that the atmosphere in the reduction furnace can be controlled, the reduced sponge iron is prevented from being secondarily oxidized, and high-quality sponge iron can be produced; the reduction speed can be controlled by adjusting the blanking speed, and the reduction degree of the product is controllable. In addition, the internal space of the combustion chamber 2 can be enlarged and the number of the reduction chambers 1 can be increased according to the requirement of production scale, thereby realizing mass production.
In the above-mentioned direct reduction step, the coal gas and volatile matter produced in each reducing chamber 1 are introduced into the middle section of the combustion chamber 2 located in the vertical direction for partial combustion, the high-temperature gas produced by combustion rises and is discharged out of the combustion chamber 2, so that the middle temperature section, the high temperature section and the low temperature section are sequentially formed in the combustion chamber 2 from top to bottom, and correspondingly, the preheating section, the reducing section and the cooling section are sequentially formed in each reducing chamber 1 from top to bottom. Correspondingly, in the reduction reaction process, the temperature in the reduction section is controlled within the range of 1000-1150 ℃. In the downward running process of the high-temperature sponge iron generated in the reduction section, the high-temperature sponge iron is gradually cooled in the cooling section, so that the high-temperature sponge iron is prevented from being secondarily oxidized when being discharged out of the reduction chamber 1. In order to improve the cooling capacity of the cooling section, a cooling mechanism can be arranged in the cooling section, for example, the cooling mode of the cooling section of the existing shaft furnace is adopted, namely a cooling gas injection structure is arranged at the lower end of the cooling section, and a cooling gas collection structure is arranged at the upper end of the cooling section; or the following structure is adopted: the cooling mechanism comprises cooling water channels arranged in furnace walls 3 of the reduction chambers in corresponding cooling sections, inlets of the cooling water channels are communicated with a cooling water supply pipe, outlets of the cooling water channels are communicated with a cooling water return pipe, and the furnace walls 3 of the reduction chambers in the cooling sections form cooling walls for cooling reduction products; the cooling water channels may be arranged in serpentine fashion in the corresponding reduction chamber furnace walls 3 to increase the heat exchange area.
The sponge iron cooled and discharged by the cooling section can be briquetted, so that the sponge iron is convenient to transport or utilize. For the shaft furnace with the cooling section, during initial material distribution, the raw material in the reduction chamber 1 needs to be supported, so the raw material or other supporting materials are distributed in the cooling section, and during initial material distribution, the firstly discharged raw material can return to a material distribution system for re-material distribution (because of the factors of heat radiation and heat conduction, the temperature of the raw material is higher than that of other initial raw materials, which is beneficial to the proceeding of reduction reaction); if other supporting materials are discharged, the material can be used for the material distribution of the next heat. Of course, the cooling mechanism is not needed, and the discharged high-temperature sponge iron is sent into electric furnace steel making or blast furnace iron making in a hot delivery mode; in this case, the combustible gas generated in the reduction chamber 1 can be introduced into the middle and lower portions of the combustion chamber 2 to be combusted simultaneously, but the combustion is not concentrated, which may cause the temperature in the reduction chamber 1 to be less than required; in this case, however, the external gas supply inlet may be provided at the lower portion or bottom of the combustion chamber 2, and during the baking process, the raw material at the lower portion of the reduction chamber 1 is subjected to the reduction reaction first, so that the lower portion of the reduction chamber 1 does not need to be provided with supporting raw material (i.e., the raw material does not need to be returned for reduction) or other supporting material.
Example two
The embodiment provides a coal-based shaft furnace direct reduction process which is low in cost and suitable for smelting laterite, wherein the reduction furnace adopts a shaft furnace, the shaft furnace comprises at least one reduction chamber 1, and each reduction chamber 1 is supplied with heat by at least one combustion chamber 2;
the process comprises the following steps:
raw material preparation: uniformly mixing iron ore concentrate powder and a binder, and pelletizing on a disc pelletizer, wherein the diameter of the pellets is about 20 mm; the bituminous coal is crushed into small lump coal with the diameter of about 24mm, and the lump coal contains 65-70 percent of fixed carbon and 30-35 percent of volatile components by mass percent;
a material distribution step: the pellets and lump coal are continuously and uniformly distributed into the reduction chamber 1 layer by layer in a furnace top feeding mode; in each reduction chamber 1, the molar ratio of carbon to oxygen in the raw materials is 1.1-1.2;
a direct reduction step: and natural gas is introduced into each combustion chamber 2 to burn and bake the furnace, raw materials in each reduction chamber 1 are subjected to reduction reaction in the furnace baking process, coal gas generated by the reduction reaction and volatile matters generated by thermal decomposition in the coal are led out from each reduction chamber 1 and uniformly introduced into each combustion chamber 2 to burn, and when the coal gas and the volatile matters introduced into the combustion chambers 2 burn and can meet the heat requirement of the reduction reaction, the supply of the natural gas is stopped. The temperature of the reduction reaction is controlled to be about 1100 ℃;
a discharging step: the produced sponge iron and coal ash waste materials are discharged from the bottom of each reduction chamber 1 and separated and recycled. In the step, the bottom of each reducing chamber 1 discharges materials and simultaneously the top of each reducing chamber 1 feeds the materials, and the discharging speed of each reducing chamber 1 is controlled to be matched with the feeding speed of the reducing chamber 1, so that continuous operation is realized.
EXAMPLE III
The embodiment provides a coal-based shaft furnace direct reduction process which is low in cost and suitable for smelting laterite, wherein the reduction furnace adopts a shaft furnace, the shaft furnace comprises at least one reduction chamber 1, and each reduction chamber 1 is supplied with heat by at least one combustion chamber 2;
the process comprises the following steps:
raw material preparation: uniformly mixing iron ore concentrate powder and a binder, and pelletizing on a disc pelletizer, wherein the diameter of the pellet is 25 mm; the bituminous coal is crushed into small lump coal with the diameter of about 35mm, and the fixed carbon content and the volatile component content in the lump coal are 71-75% and 20-28% respectively in percentage by mass.
A material distribution step: the pellets and lump coal are continuously and uniformly distributed into the reduction chamber 1 layer by layer in a furnace top feeding mode; in each reduction chamber 1, the molar ratio of carbon to oxygen in the raw materials is 1.3-1.5.
A direct reduction step: and natural gas is introduced into each combustion chamber 2 to burn and bake the furnace, raw materials in each reduction chamber 1 are subjected to reduction reaction in the furnace baking process, coal gas generated by the reduction reaction and volatile matters generated by thermal decomposition in the coal are led out from each reduction chamber 1 and uniformly introduced into each combustion chamber 2 to burn, and when the coal gas and the volatile matters introduced into the combustion chambers 2 burn and can meet the heat requirement of the reduction reaction, the supply of the natural gas is stopped. The temperature of the reduction reaction is controlled to be about 1100 ℃.
A discharging step: the produced sponge iron and coal ash waste materials are discharged from the bottom of each reduction chamber 1 and separated and recycled. In the step, the bottom of each reducing chamber 1 discharges materials and simultaneously the top of each reducing chamber 1 feeds the materials, and the discharging speed of each reducing chamber 1 is controlled to be matched with the feeding speed of the reducing chamber 1, so that continuous operation is realized.
Example four
Referring to fig. 1, the present embodiment provides an all-coal-based self-heating direct reduction shaft furnace, which comprises a combustion chamber 2 and at least one reduction chamber 1, wherein each reduction chamber 1 is in a vertically arranged cylindrical structure, and each reduction chamber 1 is arranged in an array in the combustion chamber 2; the top of each reduction chamber 1 is provided with a charging hole, and the bottom of each reduction chamber 1 is provided with a discharging hole; the upper portion of each reduction chamber 1 is provided with a gas leading-out port, the combustion chamber 2 is provided with an external gas supply inlet, a combustion air inlet and a plurality of reduction chamber gas inlets, the plurality of reduction chamber gas inlets are annularly arranged on the middle section part of the combustion chamber 2 in the vertical direction, and each reduction chamber gas inlet is communicated with at least one gas leading-out port through a gas pipe. The external gas supply inlet is connected with an external gas supply source through a gas pipeline, and the combustion air inlet is connected with the air blower through a combustion air pipeline. As the coal gas and the volatile components generated in each reducing chamber 1 are introduced into the middle section of the combustion chamber 2 in the vertical direction for partial combustion, the high-temperature gas generated by combustion rises and is discharged out of the combustion chamber 2, so that the middle temperature section, the high temperature section and the low temperature section are sequentially formed in the combustion chamber 2 from top to bottom, and correspondingly, the preheating section, the reducing section and the cooling section are sequentially formed in each reducing chamber 1 from top to bottom.
EXAMPLE five
The embodiment provides a full coal-based self-heating direct reduction shaft furnace, which comprises at least one reduction chamber 1 and at least two combustion chambers 2, wherein the reduction chamber 1 and the combustion chambers 2 are of vertically arranged cuboid structures, each combustion chamber 2 and each reduction chamber 1 are sequentially arranged, one reduction chamber 1 is arranged between every two adjacent combustion chambers 2, each reduction chamber 1 and the adjacent combustion chamber 2 are separated by a reduction chamber furnace wall 3, the top of each reduction chamber 1 is provided with a charging opening, and the bottom of each reduction chamber 1 is provided with a discharging opening; the upper part of each reduction chamber 1 is provided with a gas outlet, each combustion chamber 2 is provided with an external fuel gas supply inlet, a reduction chamber gas inlet and a combustion air inlet, the reduction chamber gas inlet is arranged in the middle of the combustion chamber 2, and each reduction chamber gas inlet is communicated with at least one gas outlet through a gas pipe; the external gas supply inlet is connected with an external gas supply source through a gas pipeline, and the combustion air inlet is connected with the air blower through a combustion air pipeline. Since the combustion chamber 2 and the reduction chamber 1 are arranged in contact with each other in sequence, the gas outlet of the reduction chamber 1, the external gas supply inlet of the combustion chamber 2, the gas inlet of the reduction chamber, and the combustion air inlet can be provided on the side surface of the corresponding furnace body (i.e., on the surface not in contact with the adjacent reduction chamber 1 or combustion chamber 2). As the external gas supply and the gas of the reduction chamber are introduced into the middle part of the combustion chamber 2 for combustion, a middle temperature section, a high temperature section and a low temperature section are sequentially formed in the combustion chamber 2 from top to bottom, and a preheating section, a reduction section and a cooling section are correspondingly sequentially formed in each reduction chamber 1 from top to bottom.
EXAMPLE six
In order to improve the cooling capacity of the cooling section, a cooling mechanism is arranged in the cooling section of the reduction shaft furnace in the fourth embodiment, for example, the cooling mode of the cooling section of the existing shaft furnace is adopted, namely a cooling air injection structure is arranged at the lower end of the cooling section, and a cooling air collection structure is arranged at the upper end of the cooling section.
EXAMPLE seven
In order to improve the cooling capacity of the cooling section, a cooling mechanism is arranged in the cooling section of the reduction shaft furnace in the fifth embodiment, the cooling mechanism comprises cooling water channels arranged in the furnace walls 3 of the reduction chambers in the corresponding cooling section, inlets of the cooling water channels are communicated with a cooling water supply pipe, outlets of the cooling water channels are communicated with a cooling water return pipe, and the furnace walls 3 of the reduction chambers in the cooling section form a cooling wall for cooling the reduction products; the cooling water channels may be arranged in serpentine fashion in the corresponding reduction chamber furnace walls 3 to increase the heat exchange area.
The shaft furnace provided by the invention is a fixed hearth, and a large and complex transmission device of most direct reduction furnaces is cancelled; the reduction zone is separated from the combustion zone, so that the atmosphere in the reduction furnace can be controlled, the reduced sponge iron is prevented from being secondarily oxidized, and high-quality sponge iron can be produced; the reduction speed can be controlled by adjusting the blanking speed, and the reduction degree of the product is controllable. In addition, because the reduction chambers 1 and the combustion chambers 2 are arranged alternately in sequence, the number of the corresponding reduction chambers 1 and the number of the corresponding combustion chambers 2 can be increased in sequence according to the requirement of production scale, and the large-scale production is realized. According to the shaft furnace, the gas outlet is formed in the upper part of the reduction chamber 1, combustible gas such as coal gas generated in the reduction process can be filled into the middle of the combustion chamber 2 for combustion, and heat is provided for the reduction chamber 1, so that the shaft furnace can realize self-heating direct reduction, a small amount of extra fuel gas is not needed or only needed, and the energy consumption and the production cost can be effectively reduced.
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 (10)
1. A reduction shaft furnace for laterite smelting comprises a combustion chamber (2) and at least one reduction chamber (1), wherein the reduction chamber (1) is of a vertically arranged cylindrical structure, and a plurality of reduction chambers (1) can be arranged in the combustion chamber (2) in an array manner; the top of the reduction chamber (1) is provided with a feed inlet, and the bottom of the reduction chamber (1) is provided with a discharge outlet; the upper portion of reducing chamber (1) is equipped with gaseous eduction port, combustor (2) are equipped with outer gas inlet, combustion air inlet and a plurality of reducing chamber gas inlet, and is a plurality of reducing chamber gas inlet ring is located combustor (2) are located the ascending middle section part of vertical side, and every reducing chamber gas inlet passes through gas pipe and at least one the gaseous eduction port intercommunication, and outer gas inlet that supplies passes through the gas pipeline and is connected with outer gas supply source, and combustion air inlet passes through combustion air pipeline and is connected with the air-blower.
2. A laterite ore autothermal equilibrium reduction process using a reduction shaft furnace according to claim 1, characterized in that said laterite ore autothermal equilibrium reduction process comprises the steps of:
raw material preparation: the method comprises the following steps of (1) drying powdery or granular laterite containing crystallization water in external water, wherein a reducing agent is common bituminous coal or power coal and other coal types, the fixed carbon content of the coal components is 30-70 wt%, and the volatile content is 20-40 wt%;
a material distribution step: uniformly mixing a coal reducing agent and laterite, and then distributing the mixture into each reduction chamber, wherein the molar ratio of carbon to oxygen in the raw materials in each reduction chamber is 0.6-1.2;
a reduction step: introducing external fuel gas into each combustion chamber to burn and bake the furnace, wherein raw materials in each reduction chamber are subjected to reduction reaction in the furnace baking process, crystal water evaporated in a high-temperature region can react with coal to generate water gas, high-temperature coal gas generated in the reduction process and volatile components generated by coal self-decomposition are recycled, the high-temperature coal gas generated in the reduction process and the volatile components generated by thermal decomposition in the coal are led out from the high-temperature section of each reduction chamber by an induced draft fan and uniformly introduced into each combustion chamber to burn, when the coal gas and the volatile components introduced into the combustion chambers burn to meet the overall heat requirement of the reduction furnace, self-heating balance is achieved at the moment, external fuel gas supply is stopped, and all the coal gas generated by the reduction chambers supplies the heat of the whole reduction furnace;
a discharging step: discharging the produced high-metallization-rate laterite product and semi-coke from the bottom of each reduction chamber, separating the product and the semi-coke through magnetic separation, and recycling the semi-coke;
and (3) recycling: the recovered semi coke is added into a new coal reducing agent according to 50 wt%, and the coal reducing agent can be recycled.
3. The laterite ore autothermal equilibrium reduction process of claim 2, characterized in that: the amount of the coal reducing agent is 50 wt% of the total mass of the raw materials.
4. The laterite ore autothermal equilibrium reduction process of claim 2, characterized in that: the furnace body of the combustion furnace can directly use coal with high volatile content, sufficient high-temperature coal gas is generated by adjusting the adding amount of the coal entering the furnace, and the high-temperature coal gas with the temperature of more than 350 ℃ is led out from the middle upper part of the reduction chamber through a high-temperature coal gas draught fan, so that the requirement of self heat supply of the reduction furnace is met, and the self-balancing utilization of heat is realized.
5. A laterite ore autothermal equilibrium reduction process according to any one of claims 2-4, characterized in that: in the reduction step, the coal gas and volatile components generated in each reduction chamber are introduced into the middle-lower section of the combustion chamber in the vertical direction for combustion, and a preheating section, a reduction section and a cooling section are sequentially formed in each reduction chamber from top to bottom.
6. A laterite ore autothermal equilibrium reduction process according to any one of claims 2-5, characterized in that: in the reduction step, the reduction reaction temperature is in the range of 900-1150 ℃, selective reduction of Ni can be realized at the lower temperature limit, and the enrichment rate of Ni in laterite is improved.
7. A laterite ore autothermal equilibrium reduction process according to any one of claims 2-6, characterized in that: in the raw material preparation step, the granularity of the coal is less than or equal to 30mm, and the coal can be all pulverized coal.
8. A laterite ore autothermal equilibrium reduction process according to any one of claims 2-7, characterized in that: the particle size of the laterite is less than or equal to 30mm, and the laterite can be completely powdery.
9. A laterite ore autothermal equilibrium reduction process according to any one of claims 2-8, characterized in that: in the discharging step, the bottom of each reduction chamber discharges continuously, the top of each reduction chamber feeds intermittently, and the discharging speed of each reduction chamber is controlled to be matched with the feeding speed of each reduction chamber, so that continuous operation is realized.
10. A laterite ore autothermal equilibrium reduction process according to any one of claims 2-9, characterized in that: the heat exchange mode through the induced draft fan is a centralized heat exchange method.
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| US11596988B2 (en) * | 2015-12-17 | 2023-03-07 | Pyro Green Innovations | Method and plant for waste treatment |
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| CN204981930U (en) * | 2015-09-01 | 2016-01-20 | 中冶南方工程技术有限公司 | It is complete coal -based from heat supply direct reduction shaft furnace |
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