Iron-containing material rotary kiln granular iron method production device

Abstract

The utility model discloses an iron-containing material rotary kiln granular iron method production device which comprises a batching machine, a mixing machine, a damp mill, a pelletizer, a drying machine, a vibrating screen, a reduction rotary kiln, a kiln back fan, a heating burner, a waste heat boiler, a cooling water pond, a ball mill, a magnetic separator, a flue gas dust remover, a smoke ventilator and a desulfurization system. The reduction rotary kiln comprises a transversely-arranged kiln body, the feeding end of the reduction rotary kiln is connected with a kiln tail cover, and the kiln tail cover is connected with a feeding port and a flue. The discharging end is connected with a kiln head cover, a discharging opening is formed in the kiln head cover, and the kiln head cover is further connected with an air nozzle and a pulverized coal burner; a preheating zone, a reducing zone and a granular iron zone are arranged in the kiln from the feeding end to the discharging end.

Description

TECHNICAL FIELD

[0001] The utility model belongs to metallurgical mineral engineering technical field, concretely relates to a kind of iron-containing material rotary kiln granulated iron method production device. BACKGROUND

[0002] Currently, rotary kiln granulated iron method is the technology for processing non-selectable low-grade acidic iron-containing material to produce granulated metallic iron, which uses non-coking coal as reducing agent and heating energy, and the iron-containing material is dried, preheated and solid-state reduced in the rotary kiln, so that iron oxides are reduced to metallic iron, and gangue in the iron-containing material is slagged. The metallic iron generated by reduction is aggregated to form iron particles with a size of 1.20-30.0 mm, and the iron particles are suspended in high-viscosity molten slag and discharged from the rotary kiln with the slag. The discharged material from the rotary kiln is water quenched, selectively crushed, and then subjected to gravity separation and magnetic separation to obtain granulated metallic iron.

[0003] Rotary kiln granulated iron method process can be divided into four parts: raw material treatment part, reduction and melting separation part, slag-iron separation part and waste gas treatment part. The raw material treatment generally involves mixing and uniformly distributing ore powder and coal powder, and using a balling disc or a ball press to form carbon-containing pellets or briquettes. The ore powder generally uses magnetite or hematite, and low-grade iron ore can also be used, even tailings powder from a concentrator. However, the use of low-grade ore increases energy consumption when processing low-grade ore. The coal powder can use ordinary coal or petroleum coke and other carbon-containing raw materials. The prepared carbon-containing pellets or briquettes are added to the rotary kiln and subjected to reduction and carburization reactions at a temperature of 1350-1450°C in the kiln, and slag and metallic iron are melted and aggregated, respectively. The entire process lasts for a short time. The molten and aggregated slag and metallic iron are cooled in an oxygen-free environment and then discharged from the rotary kiln by a discharge device to obtain granulated iron with a particle size of 5-25 mm. The high-temperature flue gas generated during the reduction process is used to preheat combustion air in a heat exchanger and then discharged after dust removal.

[0004] Currently, rotary kiln granulated iron method is mainly used in direct reduction production lines for laterite nickel ore to produce low-nickel sponge iron. The production process is as follows: (1) drying, crushing, batching and ball pressing of laterite nickel ore. The laterite nickel ore with a water content of 35-40% is dried in a drying kiln to a water content of 18-22%, and then the dried laterite nickel ore is crushed to a particle size of less than 5 mm. Finally, the crushed powder is mixed with reducing coal powder and limestone and processed into pellets in a ball press. (2) roasting and reduction process. The pellets are heated to 1250-1350°C in a rotary kiln, reducing about 80% of iron and more than 95% of nickel, while controlling the temperature of the flue gas at the kiln tail to 300-500°C, which is used for drying the laterite nickel ore. (3) crushing, grinding and magnetic separation of roasted slag. The roasted slag is crushed by coarse crushing, medium crushing and fine crushing, and then the nickel-iron with a nickel content of 7-10% is selected by a magnetic separator. The crushed roasted slag is ground by a wet ball mill, and the nickel-iron with a nickel content of 7-10% is selected by a magnetic separator.

[0005] The rotary kiln granulated iron process uses pellets or briquettes with internal carbon. Since the carbon-containing pellets or briquettes use finely ground mineral powder and coal powder, the kinetic conditions of the iron oxide reduction reaction are more advantageous than those of molten reduction and direct reduction. If the reduction temperature is increased to 1350-1450℃, the reduction and melting process of the carbon-containing pellets can be completed in one reaction device. The characteristics of the rotary kiln granulated iron process are: (1) Advantages: The reduction temperature of iron oxides and the agglomeration and growth temperature of metal particles are much lower than those of the electric arc furnace, and the content of non-iron impurities in the product is low; cheap thermal coal is used as the reducing agent and heating fuel, and no excessive additives and slag-forming agents are needed in the production process, resulting in low slag volume and low energy consumption per unit product. Compared with the electric arc furnace method and the rotary kiln pre-reduction-electric furnace smelting method (RKEF method), it has the advantages of low energy consumption, low power consumption per ton of product, low requirements for grid capacity, high iron recovery rate (about 92%), low investment, and low production cost. (1) Disadvantages: The process of feeding the furnace charge into the rotary kiln granulated iron method is complicated, the production stability is poor, the material is in a semi-molten state in the rotary kiln, and slight fluctuations in operation can easily cause problems such as adhesion and ring formation in the rotary kiln. The rotary kiln is difficult to operate and difficult to automate, resulting in low operating rate, high consumption of refractory materials, and low single-machine production capacity.

[0006] Although the rotary kiln pellet process has some of the aforementioned drawbacks, given the changing global iron ore supply conditions and considering factors such as energy consumption, environmental friendliness, production costs, and the comprehensive utilization of low-grade iron ore resources, the rotary kiln pellet process is the most economical method for producing metallic iron.

[0007] Based on the existing rotary kiln granulation iron production method for laterite nickel ore, this utility model provides a rotary kiln granulation iron production device for iron-containing materials to solve the above-mentioned problems of the existing rotary kiln granulation iron production method and to produce granulated iron using iron-containing materials and a rotary kiln as the reduction equipment. Utility Model Content

[0008] To address the aforementioned problems in existing rotary kiln granulated iron production methods and to produce granulated iron using iron-containing materials and a rotary kiln as the reduction equipment, this utility model provides a rotary kiln granulated iron production device for iron-containing materials.

[0009] Therefore, the present invention adopts the following technical solution:

[0010] A rotary kiln granulated iron production apparatus for iron-containing materials includes a batching machine, a mixer, a grinding mill, a pelletizer, a dryer, a vibrating screen, a reduction rotary kiln, a kiln back fan, heating burners, a waste heat boiler, a cooling water tank, a ball mill, a magnetic separator, a flue gas dust collector, a flue gas exhaust fan, and a desulfurization system. The reduction rotary kiln includes a horizontally arranged kiln body, with a kiln tail hood connected to the feed end, and a feed inlet and a flue connected to the kiln tail hood; a kiln head hood connected to the discharge end, with a discharge outlet provided on the kiln head hood, and air nozzles and pulverized coal burners also connected to the kiln head hood; the kiln interior, from the feed end to the discharge end, consists of a preheating zone, a reduction zone, and a granulated iron zone.

[0011] The beneficial effects of this utility model are as follows:

[0012] (1) This utility model uses iron-containing materials to produce granular iron, which has a wide range of raw material and fuel adaptability and a wide range of ore and coal types. Ordinary fine ore or ordinary non-coking coal can meet the needs of rotary kiln.

[0013] (2) The raw material pretreatment of this utility model only requires pelletizing or briquetting iron-containing materials, without the need for lump ore or coking coal, and therefore does not require sintering and coking processes, thus greatly simplifying the ironmaking process, reducing investment costs and simplifying the operation process.

[0014] (3) The iron-containing materials of this utility model are mixed with reducing agents and then lumped together. The contact area between iron oxides and reducing agents is large, which improves the reduction kinetics of iron-containing materials. Compared with the traditional blast furnace ironmaking process, the iron oxide reaction is carried out at low temperature and in a short time, resulting in lower energy consumption. It has more advantages in terms of energy saving and environmental protection than the traditional process. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the reduction rotary kiln of this utility model;

[0016] In the diagram: 1-kiln tail, 2-kiln head, 3-feed inlet, 4-flue, 5-pulverized coal burner, 6-discharge outlet, 7-preheating zone, 8-reduction zone, 9-iron strip. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0018] like Figure 1As shown, a rotary kiln granulated iron production device for iron-containing materials includes a batching machine, a mixer, a grinding mill, a pelletizer, a dryer, a vibrating screen, a reduction rotary kiln, a kiln back fan, heating burners, a waste heat boiler, a cooling water tank, a ball mill, a magnetic separator, a flue gas dust collector, a flue gas exhaust fan, and a desulfurization system. The reduction rotary kiln includes a horizontally arranged kiln body, with a kiln tail hood connected to the feed end. The kiln tail hood is connected to a feed inlet 3 and a flue 4. A kiln head hood is connected to the discharge end, with a discharge outlet 6. The kiln head hood is also connected to an air nozzle and a pulverized coal burner 5. The kiln contains a preheating zone 7, a reduction zone 8, and a granulated iron zone 9 from the feed end to the discharge end.

[0019] The working principle of this utility model is as follows:

[0020] (1) Iron-containing materials, coal powder, composite binder and return material are mixed in a ratio of 100:18:3:3 and then added to a grinding mill for water grinding. The amount of water added is 7% of the total amount of iron-containing materials and the grinding time is 3 minutes.

[0021] (2) Add the grinding material to the pelletizing disc, add water to pelletize, control the water amount to 7%, and control the particle size of the green pellets to 8-16mm;

[0022] (3) Add the wet green pellets into the cylindrical dryer and use the 350℃ medium-temperature flue gas discharged from the waste heat boiler to dry the wet green pellets. When the moisture content of the green pellets reaches below 5%, the pellets are discharged from the cylindrical dryer. At this time, the flue gas temperature drops to 180℃.

[0023] (4) The dried pellets are screened using a 5mm vibrating screen, and the undersized powder is returned to the grinding mill for reuse.

[0024] (5) The pellets on the screen are added into the kiln from the feed end of the reduction rotary kiln. Under the rotation of the reduction rotary kiln, the pellets flow from the feed end to the discharge end. The pellets exchange heat with the high temperature flue gas in the kiln. The pellets are dried and preheated during the temperature rise. When the temperature of the pellets rises to above 600℃, the iron oxides in the pellets are reduced step by step under the action of reducing coal. Finally, the iron oxides can be reduced to metallic iron.

[0025] (6) During the iron ore reduction process, metallurgical gas continuously escapes from the inside of the material layer. By setting multiple combustion fans at different positions along the kiln length on the kiln back of the reduction rotary kiln, ambient temperature air is supplied to the iron ore reduction zone inside the kiln, which allows the metallurgical gas to burn at different positions in the reduction zone inside the kiln, thereby supplying heat to the rotary kiln.

[0026] (7) The high-temperature flue gas generated after the metallurgical gas is burned in the rotary kiln exchanges heat with the pellets in the process of countercurrent flow, which can reduce the temperature of the high-temperature flue gas in the kiln and increase the temperature of the pellets.

[0027] (8) By controlling the temperature of the rotary kiln reduction zone 8 to 1380℃ and the time of the pellets in the kiln to 180min, the pellets flow to the discharge end of the reduction rotary kiln, and the temperature of the reduced pellets has reached 1300℃ and the metallization rate has reached 96%;

[0028] (9) After the reduced pellets are discharged from the discharge end of the reduction rotary kiln, they enter the water cooling pool for water cooling. When the temperature of the reduced pellets drops to 80°C, the reduced pellets are scooped out of the water pool by a ore scooping machine and added to the ball mill for wet grinding. The ground material is then magnetically separated by a magnetic separator to obtain high-purity granular iron and slag.

[0029] (10) The 650°C high-temperature flue gas discharged from the feed end of the reduction rotary kiln flows into the waste heat boiler. After the flue gas undergoes indirect heat exchange with room temperature water, it can produce medium-temperature and medium-pressure steam with a temperature of about 535°C and a pressure of about 8.8MPa, while reducing the temperature of the high-temperature flue gas to 350°C.

Claims

1. A rotary kiln granulation iron production apparatus for iron-containing materials, comprising a batching machine, a mixer, a grinding mill, a pelletizer, a dryer, a vibrating screen, a reduction rotary kiln, a kiln back fan, heating burners, a waste heat boiler, a cooling water tank, a ball mill, a magnetic separator, a flue gas dust collector, a flue gas exhaust fan, and a desulfurization system, characterized in that, The reduction rotary kiln includes a horizontally arranged kiln body, a kiln tail hood connected to the feed end, and a feed inlet and flue connected to the kiln tail hood; a kiln head hood connected to the discharge end, and a discharge port provided on the kiln head hood, which is also connected to an air nozzle and a pulverized coal burner; the kiln interior consists of a preheating zone, a reduction zone, and a granulated iron zone from the feed end to the discharge end.

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