RU2489495C2 - Metal coating complex of iron-containing raw material in form of pellets or briquettes - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: complex includes vertically located process units: a furnace for drying and pre-heating of raw material, a furnace for high-temperature heating and metal coating of raw material, as well as a metal coated raw material cooler. All the three units are of carrousel type and equipped with circular bottoms for step-by-step action on raw material. The first furnace has three temperature zones - preliminary and final drying, as well as pre-heating of pellets, each of which is equipped with a vacuum chamber and a wind box. The raw material heating and metal coating furnace located below has a reaction chamber with two process temperature zones with waveguides of energy sources of microwave frequency, is connected through a gas outlet to working space of the wind box of the temperature zone of raw material pre-heating and connected to the below located cooler with two cooling zones of metal coated raw material, which are made in the form of high-temperature and low-temperature vacuum chambers, to the lower part of which wind boxes are adjacent. High-temperature chamber of the cooler is connected to the wind box above the preliminary raw material heating zone, and low-temperature chamber of the cooler is connected to the final raw material drying zone.

EFFECT: reduction of power consumption.

3 cl, 2 dwg

Description

The invention relates to the preparation of raw materials for metallurgical processing, namely, the metallization of iron ore raw materials in the form of pellets or briquettes.

A device for the production of metallized pellets is known, which consists of a shaft-type furnace or a retort. The main elements of the device are a dual-zone shaft furnace and a reformer for the conversion of natural gas. The pre-baked pellets are loaded into the oven. Isolation of the furnace from atmospheric air is carried out using dynamic gas valves. In the furnace, pellets are lowered downward towards the reducing gas. The total residence time of the pellets in the furnace for full recovery is 8-12 hours. Metallized pellets enter the cooling zone, from which they are delivered to the belt conveyor using a sector shutter [Kudryavtsev B.C., Pchelkin SA, Lazutkin S.E. Improving the metallization technology of iron ore in OEMK // Steel. - 1987. - No. 7. - S.5-11].

The disadvantage of this device is the use of pellets that have undergone high-temperature firing with the consumption of a significant amount of thermal energy. The operation of the device is characterized by high specific costs of natural gas, the duration of the metallization process, the complexity of the process involving auxiliary equipment.

The closest technical solution, selected as a prototype, is a complex for thermal metallization of iron-containing raw materials in the form of pellets or briquettes, which contains sequentially located technological units made with the possibility of drying, preliminary high-temperature heating of the feedstock, its firing and subsequent cooling (Ukrainian patent for Utility Model No. 32484, published May 12, 2008, Bulletin No. 9).

The complex includes a loading device, a continuous conveying organ having a conveyor belt or kiln carts, drying, heating, calcining and cooling sections, as well as transfer collectors connecting the cooling section to the drying and heating sections. A chamber is located in the firing section, the surface of which is equipped with thermally insulated and magneto-dielectric screens. Inside the chamber there are placed waveguides with antennae-emitters connected to a microwave source of microwave radiation. Emitter antennas are made with the possibility of interaction of microwave radiation of superhigh frequency with raw materials on a conveyor belt or firing trolleys.

The disadvantage of the complex is that the conveying tract of technological units, which include drying, heating, as well as high-temperature firing of the feedstock to produce an iron-containing product for the metallurgical industry, made in the form of a conveyor, transfers the product from one technological process to another. Using this method of transportation does not allow minimizing energy losses and, accordingly, optimal technical and economic indicators, and according to its design features, the known device cannot provide a metallization process. In addition, the adopted method of transportation increases the length of the technological chain, which leads to the need to build a large length of technological communications, significant material and labor costs associated with the need to service the units.

The complex cannot be mounted on a limited area or executed as a modular complex, which can be moved to the place of processing of raw materials if necessary.

The objective of the invention is to improve the design of the complex for metallization of iron-containing materials through the use of rotary technological units in all cycles of processing of raw materials: from drying to metallization. Technological units are located vertically one above the other. In this case, the upper location of the unit intended for drying and preheating of the feedstock is assumed. Below is a high-temperature unit, which provides for the scheduled gradual heating of the feedstock until the end of the recovery processes and metallization of pellets or briquettes. Below the high-temperature unit, a cooling unit is located, which ensures a decrease in the temperature of metallized raw materials to the regulated value.

The claimed complex is expected to have a phased effect on raw materials at all stages of the technological process:

- when drying the raw materials, the stages of preliminary and final drying, as well as pre-heating, which ensure complete dehydration of the raw material and its preparation for metallization using microwave microwave energy, are assumed;

- during metallization, a stage-by-stage impact on raw materials with waves of ultrahigh-frequency radiation of various intensities is carried out, which provides increasing heating and a systematic process of iron reduction;

- when cooling metallized pellets or briquettes, it is supposed to utilize hot gases that have different temperatures for preheating the feedstock and its final drying.

The complex provides for the efficient utilization of the generated heat and its use for activating the drying and preheating of pellets or briquettes. In addition, the reduction of harmful emissions into the atmosphere is achieved by the use of a device for afterburning gases, the generated heat of which is also used for drying and preheating the feedstock.

Technical and social efficiency from the implementation of the claimed invention allows to reduce energy costs for the metallization of pellets or briquettes, as well as to increase the technical and economic indicators for the production of metallurgical raw materials obtained from the development of man-made deposits.

The complex can be made in the form of a compact modular installation, which can be mounted in close proximity to the place of extraction of raw materials. This ensures a reduction in the cost of transporting the feedstock and moving the complex to a new location.

The problem is solved due to the fact that the complex for the thermal metallization of iron-containing raw materials in the form of pellets or briquettes contains successive process units that are capable of drying, preliminary high-temperature heating of the feedstock, its metallization and subsequent cooling.

According to the invention, the complex contains technological units successively arranged vertically: a furnace for drying and preheating raw materials, a furnace for high-temperature heating and metallization of raw materials, a cooler for metallized raw materials. All three technological units are of a carousel type and are equipped with circular hearths for a phased effect on the processed raw materials, and the furnace for drying and preheating has three temperature zones: preliminary and final drying, as well as preheating of pellets, where the zone of preliminary drying of raw materials has a vacuum in the upper part -camera, and the bottom of the blast chamber. The final drying zone has a vacuum chamber in the upper part and a blow chamber in the lower part. The preheating zone has a blast chamber in the upper part and a vacuum chamber in the lower part. The preheating zone of the furnace has a conveying tract connected to the downstream furnace for high-temperature heating and metallization of raw materials — a reaction chamber. The working space of the reaction chamber is divided by lined partitions into at least two temperature-technological zones. Each of the temperature-technological zones of the reaction chamber has waveguides of microwave energy sources, and the reaction chamber is connected by a gas outlet to the working space of the blast chamber of the temperature zone of the preheating of raw materials and has a conveying tract with a downstream cooler, which has a heat-insulated shelter with two metallized cooling zones raw materials made in the form of high-temperature and low-temperature vacuum chambers, and under the vacuum chambers is located rotating under the cooler is made in the form of a grill, to the lower part of which are adjacent blast chambers with controlled forced supply of atmospheric air. The high-temperature cooler chamber is connected by a direct-flow heat-insulated collector to the blast chamber above the preheating zone of the raw material, and the low-temperature cooler chamber is connected by the transfer manifold to the zone of final drying of the raw material.

To increase the temperature of the exhaust gases and reduce the level of toxic emissions, the reaction chamber can be connected by a gas outlet to a device for burning off combustible gases, which is configured to supply high-temperature gases to the working space of the feed preheating zone.

To increase the metallization efficiency of iron-containing raw materials, the space of the reaction chamber can be divided by lined partitions into sectors, the opening angle of which is: in the 1st sector, 70-95 °; in the 2nd sector - 80-100 °; in the 3rd sector - 95-110 °, and the 4th sector is 50-70 °.

The claimed invention is illustrated by diagrams, where figure 1 shows a diagram of a complex for thermal metallization of iron-containing materials; figure 2 shows a diagram of a complex for thermal metallization of iron-containing materials with a device for afterburning combustible gases.

The construction of the complex and its operation are considered on the example of metallization of iron ore pellets.

The complex contains technological units successively arranged vertically from top to bottom: a drying and preheating furnace 1, a furnace for high-temperature heating and metallization 2, and a metallized raw material cooler 3. All three technological units are carousel-type and have circular hearths 4, 5, 6 for phased impact on processed iron ore.

The oven for drying and preheating 1 has three temperature zones: pre-7 and final 8 drying, as well as pre-heating 9.

The pre-drying zone of 7 pellets has a vacuum chamber 10 in the upper part and a blasting chamber 11 in the lower part.

The final drying zone 8 has a vacuum chamber 12 in the upper part and a blow chamber 13 in the lower part.

The pre-heating zone 9 has a blast chamber 14 in the upper part and a vacuum chamber 15 in the lower part. The drying and pre-heating furnace 1 is connected by a transport path 16 to the downstream furnace for high-temperature heating and metallization of raw materials 2. The upper part of the furnace 2 has a reaction chamber 17, the working space of which is divided by lined partitions (not shown in the diagram) at least into two temperature-technological zones 18, 19.

The reaction chamber 17 is connected by a gas outlet 20 to the working space of the blast chamber 14 of the temperature zone of the preheating 9 of the raw material.

Each of the temperature-technological zones 18, 19 of the furnace 2 for high-temperature heating and metallization of the pellets has waveguides of microwave energy sources 21, 22, which are connected to the generator 23.

The furnace 2 for high-temperature heating and metallization of pellets is connected by a transport path 24 with an annular cooler 3 with a rotating hearth 6. An annular cooler 3 is made in the form of a heat-insulated shelter, divided into two cooling zones for the pellets, made in the form of high-temperature 25 and low-temperature 26 vacuum chambers. The high-temperature vacuum chamber 25 is intended for cooling hot metallized pellets, and the low-temperature vacuum chamber 26 is for cooling cooling metallized pellets. Under 6 vacuum chambers, it is made in the form of a rotating grate, to the lower part of which there are adjacent blast chambers 27, 28 with controlled forced supply of atmospheric air using a compressor 29.

The high-temperature chamber 25 of the cooler 3 is connected by a direct-flow heat-insulated collector 30 to the blast chamber 14 above the preheating zone of the raw material, and the low-temperature chamber of the cooler 26 is connected by the transfer collector 31 to the zone of final drying of the raw material 8.

The resulting conditioned raw materials are located in warehouse 32.

To increase the temperature of the exhaust gases and the efficiency of their utilization, as well as to reduce the level of toxic emissions into the atmosphere, the reaction chamber is connected by a gas outlet to a device for burning combustible gases 33, which is configured to supply high-temperature gases to the working space of the pre-heating zone of raw materials 9.

To improve the metallization quality of iron ore raw materials, the space of the reaction chamber 17 is divided by lined partitions into sectors, the opening angle of which is: in the 1st sector, 70-95 °; in the 2nd sector - 80-100 °; in the 3rd sector - 95-110 ° degrees, and the 4th sector is 50-70 °.

To reduce microwave energy losses during metallization of raw materials, the reaction chamber 17 can be equipped with a cap, the inner surface of which is lined with magneto-dielectric material, which protects against radiation and reflects microwave energy, while the cap is bounded on both sides by an air gap.

Complex thermal metallization of iron ore is implemented as follows.

The raw materials for the thermal metallization of iron-containing raw materials are pellets or briquettes made of a mixture that contains an iron ore component. The production of raw materials to be metallized is carried out on the appropriate units, which provide a metered ratio of the components of the mixture and the formation of briquettes or pellets from it, which have sufficient mechanical strength, which would prevent their destruction during transportation and during the technological cycle of further processing.

In accordance with the invention, the claimed complex is made of interdependent technological units that provide the conversion of raw materials to produce the final product - metallized pellets or briquettes intended for the metallurgical industry.

The impact on raw materials occurs in stages vertically from top to bottom in each technological unit. The movement of raw materials from one unit to another takes place with the help of unloading devices along reloading chutes under the influence of gravitational forces.

In general, the complex provides for the placement of a top-down furnace for drying and preheating of raw materials 1, a furnace for high-temperature heating and metallization of raw materials 2, as well as a cooler for metallized raw materials 3.

The initial raw material enters the furnace for drying and preheating the pellets 1. Processing the raw materials in this furnace removes residual moisture and heats up for subsequent metallization.

Drying and heating of the raw materials are a preliminary operation and are realized due to the utilization of the heat generated during subsequent technological operations. Raw materials are exposed in three temperature zones. In the first temperature zone 7, pre-drying of the feedstock occurs due to the fact that the hot gaseous agent enters through the feed bed located on the rotating hearth 4 of the furnace from the blasting chamber 11 into the vacuum chamber 10 and then is emitted into the atmosphere after preliminary cleaning from the dust fraction. The residence time in the first zone 7 depends on the temperature in its atmosphere and the degree of humidity of the feedstock.

As the hearth 4 of furnace 1 moves, the raw material enters the zone of final drying 8. In this zone 8, the final drying and, correspondingly, complete dehydration of the raw material occurs similarly to the suction of hot gases, which escape through a layer of pellets or briquettes from the blast chamber 13 into a vacuum chamber 12. The final preparation of raw materials ends in the pre-heating zone of raw materials 9, where it is completely dehydrated undergoing heating with hot gases to a temperature of 600-800 ° C. Preheating of the raw material 9 by supplying hot air from the blasting chamber 14 to the vacuum chamber 15 by a suction allows to significantly reduce energy costs when producing metallized raw materials in the subsequent technological cycle.

Moving together with the rotating hearth 4, the preheated raw material enters the unloading device and further along the conveying tract 16 in the form of a chute or box on under 5 of the downstream furnace 2 for high-temperature heating and metallization of raw materials 7 - reaction chamber 17.

The peculiarity of the reaction chamber 17 is that the working heating of the raw material is carried out by means of exposure to ultra-high frequency (microwave) waves. In the reaction chamber 17, due to the lined partitions, a gradual increase in the temperature of the raw material is achieved. A different temperature is achieved due to the fact that within each temperature zone formed by the partitions, microwave energy waveguides 21, 22 are located, which are connected to the generator 23. The minimum number of temperature zones 18, 19 formed by the lined partitions is at least two. This ensures a stepwise process and smooth heating.

Studies have shown that the high quality of metallized raw materials can be achieved if the space of the reaction chamber is divided by lined partitions into four sectors, the opening angle of which is: in the 1st sector, 70-95 °; in the 2nd sector - 80-100 °; in the 3rd sector - 95-110 °, and the 4th sector is 50-70 °.

With a smaller value of the opening angle in each sector, the temperature effect on the processed raw materials is not enough, and with a larger one, an unreasonable expenditure of energy on the implementation of the metallization process is observed. In addition, the stagedness of thermal effects on metallized raw materials rises and the quality indicators of the process rise.

The high-temperature effect on the raw materials provides metal recovery - metallization to condition indicators. Metallization is accompanied by the formation of a significant amount of heat in the exhaust gases, which, due to the significant speed of the process, are partially combustible.

The high-temperature gas created in the reaction chamber is used to preheat the feedstock in the corresponding zone 9. High-temperature gas is supplied through the gas outlet 20 directly to the blow chamber 14.

After the metallization process is completed, the metal-containing raw material enters the unloading device of the reaction chamber 17 and enters the cooler under the action of gravitational forces 24 to reduce the temperature to ambient temperature.

The cooler 3 is equipped with a thermally insulated shelter with two cooling zones 25, 26 metallized raw materials. First, the metallized raw material enters the high-temperature vacuum chamber 25. In the high-temperature chamber 25 by means of the blasting chamber 27, from which air is forcedly supplied by means of blowing devices 29, the metallized pellets or briquettes are pre-cooled.

In the process of lowering the temperature, the feed enters the low-temperature vacuum chamber 26 for final cooling. In this chamber 26, similarly to the high-temperature 25, by means of the blast chamber through the grate under 6, the compressor 29 is forced to supply atmospheric air, which finally cools the metallized raw materials.

The design of the claimed complex provides for the possibility of reducing up to 25% of energy costs due to preliminary preparation of the feedstock using utilized heat. This is due to the fact that the generated hot gases are directed through the vent 20 of the reaction chamber 17 to the furnace 1 for preheating the feedstock using a blasting chamber 14 located above the hearth 4. Providing the preheating 9 of the feedstock, hot gases from the vacuum chamber 15 pre-heating zones are sent to the blasting chamber 11 for preliminary drying of pellets or briquettes. After pre-treatment, the cooled gases are removed from this chamber to the atmosphere.

It has been found that hot gases leaving the reaction chamber 17 have a certain degree of combustibility. Using this quality allows you to reduce the toxicity of gases when they are released into the atmosphere and additionally receive up to 15% of the heat that is used during the operation of the complex. To do this, the combusted gases are sent through a gas outlet to a device 35, where they are burned, from where they then enter the furnace 1 for drying and preheating the feedstock and, in particular, to the blast chamber 14 of the preheating zone of the feedstock 9.

In addition, the full utilization of hot gases is carried out during operation of the cooler 3. In the operation of the cooler 3, two-stage cooling of the feedstock is provided, therefore, accordingly, the temperature of the utilized gases is different. Gases from the high-temperature chamber 25 of the cooler are fed through a direct-flow heat-insulated collector 30 to the blast chamber 14 of the preheating zone 9 of the raw material 9 in the furnace 1, and gases from the low-temperature chamber 26 of the cooler 3 are directed using a transfer manifold 31 to the blast chamber 13 of the zone of the final drying 8 of the raw materials in the dryer furnace 1.

The resulting conditioned raw materials are located in warehouse 32.

The studies and pilot tests showed that the claimed complex is a compact high-performance design that provides the implementation of metallization technology for iron-containing raw materials for the metallurgical industry. The device allows to minimize energy and material costs for obtaining the finished product. The vertical arrangement of technological units allows you to simplify the design by moving the processed raw materials from one process stage to another through the use of gravity.

The use of differentiated thermal effects on the processed product in the drying oven and in the reaction chamber allows to obtain a systematic course of the metallization process.

Claims (3)

1. A complex for thermal metallization of iron-containing raw materials in the form of pellets or briquettes, containing successively arranged technological units for drying, preliminary and high-temperature heating of the feedstock, its metallization and subsequent cooling, characterized in that it contains a drying oven sequentially arranged vertically and pre-heating of raw materials, a furnace for high-temperature heating and metallization of raw materials and a cooler of metallized raw materials, all The technological units are made of a carousel type and equipped with circular hearths for a phased effect on the processed raw materials, and the furnace for drying and preheating of the raw material has three temperature zones - preliminary and final drying and preheating of the raw material, while the preliminary drying zone of the raw material is provided with a vacuum in the upper part -camera, and in the lower part - a blast chamber, the zone of final drying of raw materials is equipped with a vacuum chamber in the upper part and a blast chamber in the lower part, and the zone is preceded by To heat the raw material, it is equipped in the upper part with a blast chamber and in the lower part with a vacuum chamber, while the preheating zone of the furnace is equipped with a conveying duct connected to the downstream furnace for high-temperature heating and metallization of raw materials in the form of a reaction chamber, the working space of which is divided by lined partitions no less than two temperature-technological zones, while each of the temperature-technological zones of the reaction chamber has waveguides of ultra-high energy sources frequency (UHF), and the reaction chamber is connected by a gas outlet to the working space of the blast chamber of the temperature zone of the preliminary heating of the raw materials and has a transport path connected to the downstream cooler of metallized raw materials, which has a thermally insulated shelter with two cooling zones of metallized raw materials, made in the form of a high-temperature and low-temperature vacuum -chambers, moreover, under the mentioned vacuum chambers there is a rotating under the said cooler, made in the form of sieves ki, to the lower part of which there are adjacent blast chambers with controlled forced supply of atmospheric air, moreover, the high-temperature vacuum chamber of the cooler is connected by a direct-flow heat-insulated manifold to the blast chamber above the preheating zone of the raw material, and the low-temperature chamber of the cooler is connected by the transfer manifold to the zone of final drying of the raw material. 2. The complex according to claim 1, characterized in that the reaction chamber is connected by a gas outlet to a device for burning combustible gases, which is configured to supply the created high-temperature gases to the working space of the preheating zone of the feedstock. 3. The complex according to claim 1, characterized in that the space of the reaction chamber is divided by lined partitions into sectors, the opening angle of which in the 1st sector is 70-95 °; in the 2nd sector, 80-100 °; in the 3rd sector 95-110 °; in the 4th sector 50-70 °.

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