CN106367600A - A method of treating high-zinc and iron-containing dust sludge by using a rotary kiln - Google Patents

Abstract

The present invention relates to a method for treating high-zinc iron-containing dust and mud by using a rotary kiln, wherein blast furnace gas ash and converter OG mud are mixed and pelletized; wet pellets are dried and preheated, and the drying and preheating heat source is the hot air generated by the high-temperature flue gas of the rotary kiln through a high-low temperature composite air heat exchanger; a granular coal spray gun, a residual carbon spray gun and a granular ore spray gun are arranged at the kiln head of the rotary kiln, and high-volatile coal, residual carbon and high-grade iron ore are sprayed into the kiln; the dried pellets are sent to the rotary kiln, and high-temperature metallized pellets are obtained after direct reduction and high-temperature consolidation in the rotary kiln; the metallized pellets and materials such as excess residual carbon are cooled to room temperature and magnetically separated to obtain metallized pellets; the high-temperature flue gas out of the rotary kiln is subjected to large-particle dust removal, and then enters the high-low temperature composite air heat exchanger for cooling, and then enters the bag filter to recover zinc oxide powder. The present invention makes efficient use of the high-zinc iron-containing dust and mud generated by steel enterprises, and solves the environmental pollution caused by the accumulation of high-zinc iron-containing dust and mud.

Description

A method of treating high-zinc and iron-containing dust sludge by using a rotary kiln

technical field

The invention relates to the technical field of metallurgy and mineral engineering, and relates to a process for producing metallized charge and recovering zinc oxide powder from high-zinc and iron-containing dust in iron and steel enterprises.

Background technique

Iron-containing dust is the solid waste with the most types and the most complex components in the iron and steel industry. The total production volume accounts for about 5-6% of the iron and steel production, and it is the third largest solid waste after blast furnace slag and steel slag. The iron-containing dust generated in the steel production process mainly includes: sintering dust, pellet dust, blast furnace gas dust, converter OG mud, steelmaking dust, casthouse dust, etc. The main component of iron-containing dust sludge is iron, and its iron content is generally TFe30-65%, and it also contains certain harmful elements such as Zn, K, Na, etc. Among them, the Zn content of blast furnace gas mortar can reach 7-10%. This is called high-zinc iron-containing dust.

In iron and steel enterprises, zinc in ironmaking and steelmaking dust mainly exists in the form of ZnO. When iron-containing dust is used for sintering, since the sintering process is an oxidizing atmosphere, the zinc oxide contained in the material will still remain in the sintering process. In the mine, it will eventually cause the cyclic enrichment of zinc in the blast furnace, affecting the normal production of the blast furnace. At present, except for sintering dust removal and pellet dust removal, which are used by sintering machines, other high-zinc iron-containing dust sludge is accumulated in large quantities.

At present, there is a process of using a rotary kiln to treat high-zinc and iron-containing dust, but there are problems such as low ZnO content in the collected zinc ash, low dezincification rate, low metallization rate of the reduced material, and low production capacity of the rotary kiln. At present, the rotary kiln process for processing high-zinc and iron-containing dust sludge does not make pellets, so a large amount of dust is generated during the rotation of the rotary kiln, and the dust enters the dust removal system with the flue gas, and enters the zinc ash after bag dust removal, making the collected zinc ash ZnO As no measures have been taken to strengthen the reducing atmosphere in the kiln, the reducing atmosphere is weak in the middle and later stages of high-temperature reduction, and the reduction reaction speed decreases or even stagnates, resulting in low metallization rate of the reduced material and zinc content in the reduced material Still high (about 1%), low dezincification rate, low production capacity of rotary kiln and other problems.

Contents of the invention

In order to solve the above technical problems, the present invention proposes a method for treating high-zinc iron-containing dust and sludge by using a rotary kiln.

The technical scheme adopted in the present invention is: a method for treating high-zinc iron-containing dust sludge by using a rotary kiln, the steps of which are: (1) Blast furnace gas ash and converter OG mud are mixed in a ratio of 30-40:60-70 and mixed , using the disc pelletizing method to produce wet pellets with a particle size of 8-15mm; (2) The wet pellets are transported to the chain grate machine or belt dryer through the belt for drying and preheating. The heat source required for drying and preheating is rotary The high-temperature flue gas of the kiln passes through the hot air generated by the air heat exchanger; (3) The temperature of the pellets after drying and preheating is about 500°C, and the pellets are sent into the rotary kiln by a chain grate machine or a belt dryer. After direct reduction and high-temperature consolidation at a kiln temperature of 1050-1100°C for 90-120 minutes, high-temperature metallized pellets are obtained. The rotary kiln burns carbon-containing fuel to release heat, and the high-temperature metallized pellets are mixed with residual carbon; (4 ) After the high-temperature metallized pellets mixed with residual carbon are cooled to normal temperature, they are separated by magnetic separation through a dry magnetic separator to separate magnetic materials and non-magnetic materials, and obtain metallized pellets with high metallization rate and strength and For non-magnetic materials, the obtained metallized pellets are used in blast furnaces or converters. After the non-magnetic materials are screened by a 3mm vibrating screen, the -3mm part is discharged as the ash discharge point of the entire system, and the +3mm part is separated by a mineral separator. Waste rocks, waste rocks are discharged, and residual charcoal is used as recyclable materials for recycling; (5) The rotary kiln is equipped with a secondary combustion chamber, and the high-temperature flue gas exiting the rotary kiln passes through the secondary combustion chamber to incompletely exhaust the flue gas discharged from the rotary kiln. The burned combustibles undergo secondary combustion. The flue gas is further removed by the gravity dust collector to remove large particles of dust, and then enters the high-low temperature composite air heat exchanger for cooling. After the flue gas is cooled, the temperature drops to 180-200°C, and then enters the bag filter. , Recovery of dust containing zinc oxide powder, the recovery of dust containing zinc oxide powder contains ZnO 50 ~ 60%.

The flue gas temperature received by the high-low temperature composite air heat exchanger is not greater than 1000°C, and the communication channel between the high-low temperature composite air heat exchanger and the secondary combustion chamber is provided with a cooling fan, and when the secondary combustion chamber discharges the flue gas When the temperature is higher than 1000°C, the cooling fan is turned on, and cold air is blown into the communication channel. After the high-temperature flue gas is mixed with cold air, the temperature is lowered to below 1000°C. The high-low temperature composite air heat exchanger is a secondary heat exchanger, and the first stage The high-temperature section is a ceramic heat exchanger, which can reduce the temperature of high-temperature flue gas to about 600°C and generate high-temperature hot air at 500-700°C. The second-stage low-temperature section is a metal heat exchanger, which can reduce the temperature of high-temperature flue gas from about 600°C. Lower to 180-200°C, and generate 300-400°C low-temperature hot air; 300-400°C hot air generated by the high-low temperature composite air heat exchanger is blown into the drying section of the chain grate machine or belt dryer, as a heat source for drying wet pellets , part of the 500-700°C hot air generated is blown into the preheating section of the chain grate machine or belt dryer as a heat source for pellet preheating; part of it is blown into the kiln from the rotary kiln head as high-temperature combustion-supporting air.

The drying and preheating time of the wet pellets is 20-40 minutes.

The cooling mechanism used when the high-temperature metallized pellets mixed with residual carbon are cooled to normal temperature is an indirect water-cooled cooling cylinder.

A dust collection funnel is arranged in the flue gas channel of the high-low temperature composite air heat exchanger to further remove dust in the flue gas, thereby increasing the ZnO content in the recycled flue dust containing zinc oxide powder.

At the kiln head of the rotary kiln, a granulated coal spray gun, a residual carbon spray gun and a granulated ore spray gun are installed. The granular coal spray gun sprays high-volatile coal with a particle size of 5-15mm, and the proportion of the granulated coal injected is 5-10% of the pellet mass; The particle size of the carbon spray gun is 3-15mm residual carbon, and the proportion of the injected residual carbon is 3-5% of the mass of the pellets; The proportion is 15-20% of the pellet mass.

Further, take the outlet of the kiln head as the starting point of the length of the rotary kiln, inject high-volatile coal with a particle size of 5-15mm to 1/2-1/3 of the length of the rotary kiln, and inject residual carbon with a particle size of 3-15mm To 3/5~1/2 of the length of the rotary kiln, the high-grade iron ore with a particle size of 5~10mm is injected to 1/2~1/3 of the length of the rotary kiln; the high volatile coal injected into the kiln At high temperature in the kiln, the volatile matter is released, and the _H2 in the volatile matter acts as a reducing agent when passing through the material layer, and the C in the high-volatile coal and the C in the residual carbon and the _CO2 produced in the material layer generate carbon gas The reaction releases CO, realizes the combined reduction of carbon and hydrogen, and increases the reduction reaction speed. After the high-grade iron ore particles are sprayed into the kiln, the iron oxides in the granular ore react with the CO in the material layer to release CO under high temperature in the kiln. ₂ , CO ₂ is used as an "oxygenating agent" to undergo a carbon gasification reaction with C in the highly volatile granular coal and C in the residual carbon injected into the kiln to release twice as much CO, which enhances the reducing atmosphere in the material layer, Improve the kinetic conditions of the reduction reaction, which is the "oxygenation" effect of high-grade granular ore.

The beneficial effects obtained by the present invention are: 1. The present invention effectively utilizes the iron and carbon resources in the dust and greatly reduces the harmful alkali metals such as zinc, potassium and sodium in the dust while processing high-zinc and iron-containing dust; elements, reducing the alkali metal load of the blast furnace, which is of great significance to improving the service life of the blast furnace;

2. By using the rotary kiln to process high-zinc iron-containing dust and sludge, not only can high-quality zinc oxide powder be recovered, but also metallized pellets with high metallization rate and strength can be produced for use in blast furnaces;

3. By injecting high-volatile granular coal, residual carbon, and granular ore at the kiln head, the joint reduction of carbon and hydrogen is realized, the reducing atmosphere in the middle and later stages of the reduction reaction is enhanced, and the reduction reaction of iron and zinc oxides is strengthened, which solves the problem of Rotary kiln to deal with the problems of low metallization rate and high zinc content of high-zinc iron-containing dust sludge;

4. The present invention makes efficient use of the high-zinc and iron-containing dust produced by iron and steel enterprises, and solves the environmental pollution caused by the accumulation of high-zinc and iron-containing dust.

Description of drawings

Fig. 1 is a process flow diagram of the present invention;

Fig. 2 is a schematic diagram of the device relationship of the present invention.

detailed description

The present invention utilizes ironmaking and steelmaking high-zinc iron-containing dust sludge produced in the production process of iron and steel enterprises to produce metallized charge for blast furnace or converter. ～40: 60～70 ratio of ingredients and mixing, the disc pelletizing method is used to produce wet pellets with a particle size of 8-15mm; (2) The wet pellets are conveyed to the chain grate machine (or belt dryer, drying section and preheating section) for drying and preheating, and the heat source for drying and preheating is the hot air generated by the high-temperature flue gas of the rotary kiln passing through the air heat exchanger. The exhaust gas temperature of the rotary kiln is above 800°C. A secondary combustion chamber is installed behind the rotary kiln to perform secondary combustion on the unburned combustibles in the flue gas discharged from the rotary kiln. The temperature of the flue gas discharged from the secondary combustion chamber is about 1000°C. , The flue gas from the secondary combustion chamber passes through the high-low temperature composite air heat exchanger to generate high-temperature hot air (500-700°C) and low-temperature hot air (300-400°C). Before the flue gas from the secondary combustion chamber enters the high-low temperature composite air heat exchanger, a cooling fan is installed for protection. When the temperature of the flue gas discharged from the secondary combustion chamber is greater than 1000 ° C, the cooling fan is turned on. The high-low temperature composite air heat exchanger is a two-stage heat exchanger, and the first-stage high-temperature section is a ceramic heat exchanger, which can reduce the temperature of high-temperature flue gas from about 1000°C to about 600°C, and generate high-temperature hot air at 500-700°C ; The second low-temperature section is a metal heat exchanger, which can reduce the temperature of high-temperature flue gas from about 600°C to 180-200°C, and generate low-temperature hot air at 300-400°C. The low-temperature hot air (300-400°C) generated by the high-low temperature composite air heat exchanger is blown into the drying section of the chain grate machine (or belt dryer) as the heat source for drying the wet pellets, and the high-temperature hot air (500-700°C) generated Part of it is blown into the preheating section of the chain grate machine (or belt dryer) as a heat source for pellet preheating; the other part is blown into the kiln from the rotary kiln head as high-temperature combustion-supporting air. The drying and preheating time of the wet pellets on the chain grate machine (or belt dryer) is 20 to 40 minutes; (3) The granular coal spray gun, residual carbon spray gun and granular ore spray gun are installed at the kiln head of the rotary kiln. Blow particle size of 5 ~ 15mm high volatile coal, the proportion of pelletized coal injection is 5 ~ 10% of the amount of pellets; residual carbon spray gun injection particle size of 3 ~ 15mm residual carbon, the proportion of injection residual carbon is the amount of pellets 3-5% of the pellets; the particle size of the ore spray gun is 5-10mm high-grade iron ore, and the proportion of the high-grade iron ore injected is 15-20% of the pellets; (4) The pellets after drying and preheating ( The temperature is about 500°C) is sent to the rotary kiln by the chain grate machine (or belt dryer), and after direct reduction and high-temperature consolidation at a kiln temperature of 1050-1100°C and a time of 90-120 minutes in the rotary kiln, high-temperature metallization is obtained pellets. The high-temperature mixed material composed of metallized pellets and excess residual carbon is cooled to room temperature by an indirect water-cooled cooling cylinder, and then magnetically separated by a dry-type magnetic separator to separate magnetic materials and non-magnetic materials, and the metallization rate is obtained. And metallized pellets with high strength and non-magnetic materials (residual carbon and waste rock). The metallized pellets are supplied to blast furnaces or converters. After the non-magnetic materials are screened by a 3mm vibrating screen, the -3mm part is used as the discharge of the entire system. The ash point is discharged, and the +3mm part is separated into residual carbon and waste rock by the mineral separator, and the waste rock is discharged, and the residual carbon is returned to the residual carbon silo at the kiln head of the rotary kiln, and then sprayed into the kiln by the residual carbon spray gun at the rotary kiln head for circulation Use; (5) The high-temperature flue gas from the rotary kiln passes through the secondary combustion chamber to carry out secondary combustion of the unburned combustibles in the flue gas discharged from the rotary kiln, and then removes large particles of dust through the gravity dust collector, and then enters the high-temperature The low-temperature composite air heat exchanger is cooled, and the temperature of the flue gas is reduced to 180-200 °C after cooling, and then enters the bag filter to recover zinc oxide powder dust, which contains 50-60% ZnO.

Set a granular coal spray gun at the kiln head of the rotary kiln, inject high-volatile coal with a particle size of 5-15mm to a place 1/2-1/3 of the length of the rotary kiln from the outlet of the kiln head, and spray the residual coal with a particle size of 3-15mm The charcoal is injected to the 3/5~1/2 of the length of the rotary kiln from the kiln head outlet. The distance from the exit of the kiln head is 1/2 to 1/3 of the length of the rotary kiln, which is roughly in the middle and rear of the high-temperature reduction section in the kiln, where most of the carbon in the gas ash has been consumed, and the reducing atmosphere in the material layer is relatively weak After throwing high-volatility granular coal, C in high-volatility granular coal and C in residual carbon will undergo carbon gasification reaction with CO2 generated in the material layer to release CO, which enhances the reducing atmosphere in the material layer and improves the The kinetic conditions of the reduction reaction are conducive to increasing the reduction reaction rate. At the same time, the high-volatile granular coal injected into the kiln releases volatile matter at high temperature in the kiln. Combustible substances such as CH ₄ , tar, benzene, and naphthalene in the volatile matter are burned in the rotary kiln as heating fuel. When _H2 passes through the material layer, it will be used as a reducing agent to reduce the iron oxide in the material layer. Since _H2 has the characteristics of strong low-temperature reducing ability and strong penetrating ability, it is very beneficial to increase the reduction speed. In the early stage of reduction, when the pellet temperature is lower than 800°C, _H2 reduction is the main method; in the middle and later stages of reduction, when the pellet temperature is higher than 800°C, CO reduction is the main method. This is the combined hydrocarbon reduction technology.

The granular ore spray gun is installed at the kiln head of the rotary kiln, and the high-grade granular ore with a particle size of 5-10 mm is sprayed to a place 1/2 to 1/3 of the length of the rotary kiln from the outlet of the kiln head. The distance from the exit of the kiln head is 1/2 to 1/3 of the length of the rotary kiln, which is roughly in the middle and rear of the high-temperature reduction section in the kiln, where most of the carbon in the gas ash has been consumed, and the reducing atmosphere in the material layer is relatively weak . After injecting granular ore, at high temperature in the kiln, the iron oxide in the high-grade granular ore injected into the kiln undergoes a reduction reaction with _CO in the material layer to release CO ₂ . The carbon gasification reaction of C in the highly volatile granular coal and C in the residual carbon in the kiln releases twice the amount of CO, which enhances the reducing atmosphere in the material layer, improves the kinetic conditions of the reduction reaction, and is conducive to improving the reduction reaction. Speed, this is the "oxygenation" effect of high-grade granular ore.

After the high-temperature flue gas exiting the rotary kiln passes through the secondary combustion chamber, it first passes through the gravity dust collector to remove large particles of dust, and then enters the high-low temperature composite air heat exchanger for cooling. After cooling, the temperature drops to 180-200°C. The low-temperature hot air (300-400°C) generated by the high-low temperature composite air heat exchanger blows into the drying section of the chain grate machine (or belt dryer) as a heat source for drying wet pellets; the generated high-temperature hot air (500-700°C) Part of it is blown into the kiln from the head of the rotary kiln as high-temperature combustion-supporting air, and part of it is blown into the preheating section of the chain grate machine (or belt dryer) as a heat source for pellet preheating. Since the high-temperature flue gas heat of the rotary kiln is recycled, fuel consumption can be effectively reduced.

The high-temperature flue gas exiting the rotary kiln first passes through the gravity dust collector to remove large particles of dust, and then enters the high-low temperature composite air heat exchanger for cooling. A dust collection funnel is installed in the flue gas channel of the high-low temperature composite air heat exchanger, which can further The dust in the flue gas is removed, which increases the ZnO content in the zinc oxide powder recovered by the bag filter.

The high-zinc iron-containing dust sludge used in the present invention contains relatively high zinc oxide. Under the high temperature and reducing atmosphere of the reduction furnace, zinc oxide is reduced to metallic zinc. Since the melting point of metallic zinc is 419.53°C and the boiling point is 907°C , the generated metal zinc is gasified at high temperature in the kiln, and discharged with the flue gas in the form of zinc vapor. Metal zinc vapor encounters an oxidative atmosphere and oxidizes again to form fine zinc oxide solid particles. After being collected by bag dust removal, a by-product with a zinc oxide content of 50-60% can be obtained. Therefore, the method can not only produce metallized pellets, but also have the functions of dezincification and zinc collection.

When the present invention adopts the mixture of blast furnace gas ash and converter OG mud to make pellets, according to the characteristics of converter OG mud particle size is finer and the content of CaO is higher, pelletizing is carried out without adding binder.

1. Selection of materials

Blast furnace gas ash: iron grade 25-41%, SiO ₂ content 2-8.5%, ZnO content 4-8%, K ₂ O content 0.6-0.8%, Na ₂ O content 0.15-0.20%, C content 15-36 %;

Converter OG mud: After drying and grinding, the particle size is -200 mesh, accounting for more than 80%, the iron grade is 42-65%, the SiO ₂ content is 2-4%, the ZnO content is 0.2-0.4%, and the K ₂ O content is 0.1-0.3%. Na ₂ O content 0.1-0.3%;

High volatile coal: fixed carbon content of 44-46%, ash content of 7-9%, volatile content of 47-49%, injection high-volatile coal particle size of 5-15mm;

2. Ingredients and mixing of raw materials

Blast furnace gas ash and converter OG mud are batched and mixed according to the ratio of 30-40:60-70 to obtain a mixed material.

3. Ball making

The mixed material is added to the disc pelletizer, and 7-10% water is sprayed into the disc or cylinder to pelletize, and the particle size of the cue ball is controlled to be 8-15mm;

4. Wet pellet drying and preheating

Wet pellets with a particle size of 8-15mm are transported to the chain grate machine (or belt dryer) by belt for drying and preheating. The heat source for drying and preheating is the hot air generated by the high-temperature flue gas from the rotary kiln passing through the high-low temperature composite air heat exchanger. , the temperature of the low-temperature hot air in the drying section of the supply chain grate machine (or belt dryer) is 300-400°C, the temperature of the high-temperature hot air in the preheating section of the supply chain grate machine (or belt dryer) is 500-700°C, and the wet pellets are The drying preheating time on the chain grate machine (or belt dryer) is 20-40 minutes;

5. Reduction and consolidation of pellets

During the reduction and roasting process of the pellets, by controlling the temperature of the rotary kiln at 1050-1100 °C and the time of 90-120 minutes, the pellets can be uniformly reduced and consolidated in the process of heating up and high-temperature reduction, and the pellets The strength of the furnace is improved; by injecting high-volatile granular coal, residual carbon, and high-grade granular ore at the kiln head of the rotary kiln, the joint reduction of hydrocarbons and hydrogen is realized, the reducing atmosphere in the middle and later stages of the reduction reaction is enhanced, and the reduction speed is increased.

6. Material cooling and separation

After the high-temperature reduction material is cooled to normal temperature by an indirect water-cooled cooling cylinder, it is magnetically separated by a dry magnetic separator to obtain metallized pellets with high metallization rate and strength.

7. Recovery of zinc oxide

The high-temperature flue gas exiting the rotary kiln first passes through the gravity dust collector to remove large particles of dust, and then enters the high-low temperature composite air heat exchanger for cooling. After cooling, the temperature drops to 180-200°C, and then enters the bag filter to recover zinc oxide powder dust , containing ZnO 50-60%.

Claims (7)

1. a kind of method that utilization rotary kiln processes high-Zinc and Ferric dust, the steps include: that (1) blast furnace dust, converter og mud are pressed After 30～40:60～70 ratio dispensing and mixing, the wet bulb group that granularity is 8～15mm is produced using disk pelletizing process；(2) wet Pelletizing is transported to grate or band drier through belt, and being dried thermal source needed for preheating, drying and preheating is rotary kiln high temperature The hot blast that flue gas produces through air heat exchanger；(3) temperature after the preheating of pelletizing drying is 500 DEG C about, and pelletizing is by grate Or band drier send into rotary kiln, in rotary kiln through 1050～1100 DEG C of kiln temperature, time 90～120min directly and also After former and high-temperature concretion, obtain high-temperature metal pellet, rotary kiln is mixed with by carbon-containing fuel combustion heat release, high-temperature metal pellet Carbon residue；(4) be mixed with carbon residue high-temperature metal pellet be cooled to room temperature after, through dry-type magnetic extractor carry out magnetic separation separate, isolate Magnetic material and non-magnetic material, obtain degree of metalization and the higher metallized pellet of intensity and non-magnetic material, gained metal Pellet supply blast furnace or converter use, and, after 3mm bolting, -3mm part is as the row of whole system for non-magnetic material Ash point is discharged, and+3mm part separates carbon residue and barren rock through minerals separation machine, and barren rock is discharged, and carbon residue, as recoverable material, reclaims Using；(5) rotary kiln sets secondary combustion chamber, goes out in the flue gas that rotary kiln is discharged through secondary combustion chamber by the high-temperature flue gas of rotary kiln Imperfect combustion combustible carries out second-time burning, and flue gas removes big dust particle through gravitational precipitator further, then enters High/low temperature composite air heat exchanger cools down, and after flue gas cooling, temperature is down to 180～200 DEG C, subsequently into sack cleaner, reclaims Flue dust containing oxide powder and zinc, the flue dust containing oxide powder and zinc of recovery contains zno 50～60%.

2. the method that utilization rotary kiln according to claim 1 processes high-Zinc and Ferric dust, is characterized in that: described high/low temperature The flue-gas temperature that composite air heat exchanger accepts is not more than 1000 DEG C, between high/low temperature composite air heat exchanger and secondary combustion chamber Communicating passage be provided with and mix air-cooler, when secondary combustion chamber is discharged flue-gas temperature and is more than 1000 DEG C, mix air-cooler and open, Xiang Lian Circulation passage is blown into cold wind, and high-temperature flue gas are cooled to less than 1000 DEG C after blending cold wind, and described high/low temperature composite air heat exchanger is Secondary heat exchanger, first order high temperature section is ceramic heat exchanger, high-temperature flue-gas can be down to 600 DEG C about, and produce 500～ 700 DEG C of high-temperature hot-air, second level low-temperature zone is metallic recuperator, high-temperature flue-gas are down to 180 by 600 DEG C about～ 200 DEG C, and produce 300～400 DEG C of low temperature hot blast；300～400 DEG C of hot blasts that high/low temperature composite air heat exchanger produces blast Grate or band drier dryer section, roll into a ball drying source as wet bulb, and 500～700 DEG C of hot blast parts of generation blast chain Grate machine or band drier preheating section, preheat thermal source as pelletizing；A part is blasted in kiln by rotary kiln end and helps as high temperature Combustion wind.

3. the method that utilization rotary kiln according to claim 1 processes high-Zinc and Ferric dust, is characterized in that: the drying of wet bulb group The time of preheating is 20～40min.

4. the method that utilization rotary kiln according to claim 1 processes high-Zinc and Ferric dust, is characterized in that: be mixed with carbon residue It is indirect type cooling by water cylinder that high-temperature metal pellet but arrives cooling body used during room temperature.

5. the method that utilization rotary kiln according to claim 1 processes high-Zinc and Ferric dust, is characterized in that: in rotary kiln Head setting beans spray gun, carbon residue spray gun and grain ore deposit spray gun, beans spray gun injection granularity is 5～15mm fat coal, is blown grain The ratio of coal is the 5～10% of pellet quality；Carbon residue spray gun injection granularity is 3～15mm carbon residue, and the ratio of injection carbon residue is pelletizing The 3～5% of quality；Grain ore deposit spray gun injection granularity is 5～10mm high-grade iron mine, and the ratio of injection high-grade iron mine is pelletizing matter The 15～20% of amount.

6. the method that utilization rotary kiln according to claim 5 processes high-Zinc and Ferric dust, is characterized in that: with kiln hood outlet For the long starting point of rotary kiln, granularity is that 5～15mm fat coal is blown at the 1/2～1/3 of rotary kiln length, and granularity is 3 The carbon residue of～15mm is blown at the 3/5～1/2 of rotary kiln length, and granularity is blown rotary kiln for 5～10mm high-grade iron mine At the 1/2～1/3 of kiln length；The fat coal being blown into kiln, under high temperature in kiln, releases fugitive constituent, the h in fugitive constituent₂Wearing Cross as reducing agent during the bed of material, the c in the fat coal and c in the carbon residue co that produce interior with the bed of material₂There is gasification reaction Release co it is achieved that hydrocarbon combine reduction, improve reduction reaction speed, after high grade iron ore particle sprays into kiln, under high temperature in kiln, Iron oxides in grain ore deposit are reacted with material in the layer co and release co₂, co₂As " oxygenation agent " and the high volatilization spraying in kiln C in the beans and c in carbon residue occurs gasification reaction to release the co of twice, enhances material in the layer reducing atmosphere, improves Kinetics of reduction condition.

7. the method that utilization rotary kiln according to claim 1 processes high-Zinc and Ferric dust, is characterized in that: in described height Setting dust funnel in the exhaust gases passes of warm composite air heat exchanger, the dust in removing flue gas, is improved back with this further Zno content in the flue dust containing oxide powder and zinc received.