Dust control measures for the hottest metallurgica

Dust prevention and dust removal measures for metallurgical sintering enterprises

sintering plant is one of the units with the most serious dust pollution in metallurgical enterprises at present. The amount of dust produced by sintering plant is large, the influence is wide, the treatment is difficult, and the harm is serious. A 75m2 sintering machine produces 3.9105 RN3 of waste gas per hour and about 1.5 T of scattered dust. The main dust sources in the sintering production process are: ① dust in the exhaust of the main flue of the sintering machine; ② Dust generated during discharging at the tail of sintering machine and cooler; ③ Dust generated during screening of sinter; ④ Dust generated during the transportation of finished products and ore return; ⑤ Dust in primary mixed exhaust gas; ⑥ Dust generated during unloading, processing (crushing, screening) and transportation of raw materials, fluxes and fuels for sintering; ⑦ Ash discharge treatment of dry dust collector; ⑧ Secondary dust

all kinds of dust sources have their own characteristics: there are many and scattered dust sources in the raw material preparation system; The mixture system, especially when the hot return ore takes part in the mixing, the dust and gas coexist, and the exhaust gas has high temperature, high humidity and high dust concentration. The amount of waste gas in the sinter system is large, the temperature is high, and the dust concentration is high. At present, self fusible or high basicity sinters are mostly produced, so the specific resistance of powder and dust is high. In addition, the sintering dust is highly abrasive, and the waste gas contains SO2 and Cao, which is easy to produce corrosion and scaling, making the treatment of sintering dust difficult

1. Dust prevention measures for sintering process

dust removal in sintering plant should first start with reforming process and facilities and improving automation level to reduce dust sources and dust emissions. There are mainly the following aspects:

(1) automatic batching and strict control of mixture moisture and ignition temperature, so that the finished sinter has high quality, high strength, low pulverization rate, and dust can be reduced.

(2) using the bottom laying sintering process, the sinter with a particle size of 10 ~ 20mm and a material layer thickness of 30 ~ 50mm is first laid on the sintering machine, which can burn the batch thoroughly, and the finished sinter does not contain raw materials, Reduce the amount of dust

(3) the quicklime used in the intensified sintering process is transported by wind to realize closed transportation, which can avoid the dust from belt transportation

(4) the sintering machine adopts the direct feeding mode to the cooler at the tail, cancels the hot screen at the tail, and adopts the cold return ore proportioning scheme, so as to eliminate the situation of a large amount of water vapor entrained dust flying during the hot return ore proportioning

(5) connect the high-temperature waste gas discharged from the feeding point of the ring cooler to the igniter for combustion support, and the dust is absorbed when the waste gas passes through the trolley material layer, so as to reduce the dust emission.

(6) the sintering equipment is large-scale and automated, reducing the dust receiving personnel and reducing the dust receiving opportunities of personnel, which is the development direction of dust prevention in the sintering plant in the future

2. Dust removal measures in sintering plants

the development trend of dust removal measures in modern sintering plants is:

(1) at present, most of the dust removal equipment in the exhaust system of sintering plants still use mechanical cyclone dust collectors or multi tube dust collectors, and the purification efficiency can only reach 70 ~ 90% of the discharged dust concentration, which cannot meet the national health standards. At present, centralized large-scale dust removal system and advanced large-scale dust removal equipment are mostly used, which is convenient for centralized management and maintenance, conducive to the continuous normal operation of the dust collector, centralized dust recovery and treatment, and reduce secondary dust. In the first phase project of Baosteel sintering plant, the whole plant is equipped with five centralized dust removal systems, namely, exhaust gas, tail, batching, finished products and pulverized coke. The purification equipment adopts escs-600 linear horizontal three room wide spacing electrostatic precipitator, Mitsubishi Lurgi electrostatic precipitator and large suction reverse suction bag type dust collector, which has achieved good dust removal effect. For the design of electrostatic precipitator, attention is paid to the uniform distribution of air flow, the two production lines of automobile lightweight parts in the electric field and the ash phase II Industrial Park, and the four full-automatic piston production lines. After the completion, the bucket is equipped with a baffle plate, the anode is equipped with a 480mm large groove plate, the outlet is equipped with a groove plate, and the high-performance power supply is used to improve the level of electrostatic precipitator

(2) reasonable dust treatment and recovery. Due to the centralization and large-scale of the system, the dust recovered by the dust removal system is concentrated in several points, and then the powder is sent to the sintering process system for recycling after closed transportation or humidification

3. Sintering waste gas dedusting

in recent years, some units have added a cyclone or inert deduster between the dust fall tube and the multi tube deduster, so that the dust concentration can meet the emission standard. The readings of the pressure gauge that has been tested have adopted the design of electrostatic precipitator in the waste gas dust removal system of the sintering plant, and will soon be put into operation. Baosteel's sintering waste gas dust removal system adopts ESCs type ultra-high voltage, wide polar distance electrostatic precipitator to purify high specific resistance dust, and has preliminarily gained experience

4. Sintering plant environmental dust removal

raw material preparation, mixture, finished sinter and other dust removal systems in the sintering plant are generally called environmental dust removal systems, including the following aspects:

(1) dust removal measures of raw material preparation system

raw material preparation system in the sintering plant refers to the process of storage, processing, transportation and batching of ferrous raw materials, fluxes and fuels used in sintering. In the past, the dust removal system of the raw material preparation system was decentralized, and there were various methods. Usually, hydraulic dust removal, combined hydraulic and mechanical dust removal, mechanical cyclone dust removal, high-voltage electrostatic dust source control and other measures were used, and the dust removal effect was not ideal. At present, centralized large-scale dust removal equipment has been adopted, such as the batching and dust removal system of Angang No. 2 sintering plant, which is now in operation. There are several dust collection points, and the total dust removal air volume is 26 x 104 m3/h. The dust removal equipment adopts a dry-type horizontal electric precipitator with two chambers and two electric fields of 85m2, and the collected dust is transported to the process batching belt by a screw machine for recycling

in the raw material preparation system, there are still some open dust sources. For example, many belt conveyors do not have reliable dust prevention facilities. If high-voltage electrostatic dust source control devices are used at the dust source points, or charged water mist is sprayed at the dust source points, these open dust sources can be effectively suppressed

(2) dust removal of mixture system

the mixture system in the sintering plant is a process in which the mixture is moistened and pelleted by special mixing equipment before being loaded into the sintering machine. If the sintering plant is a hot ore process, the hot return ore will produce a large amount of powder and water vapor when encountering water, which will worsen the mixture environment. If it is allowed to discharge naturally, it will cause great harm. According to different processes and operation methods, large impact dust collectors can be used at the main dust source points such as the water adding point of the ore return belt and the primary mixing cylinder mixer, and spray pipes or spray boxes can be used at other secondary dust source points to purify the exhaust

(3) dust removal of finished sinter system

finished sinter seriously restricts the transformation and upgrading of the industry. The sintering system refers to the process processes such as sinter tail unloading department, cooling equipment and pelletizing facilities. The dust concentration of each dust source point of this system is high, and the treatment air volume is large, which is the main part of dust removal in sintering plant. The first is the dust removal at the tail of the machine. At present, electrostatic precipitators are mostly used. The second is the dust removal of whole grain facilities. The dust removal measures are to set up a medium or decentralized dust removal system according to the process production system, which integrates this kind of plastic granulator equipment with very serious environmental pollution. Electrostatic precipitators or annular pulse bag filters are used