Dust control measures for the hottest metallurgica

2022-07-26
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Dust prevention and dust removal measures for metallurgical sintering enterprises at present, sintering plant is one of the units with the most serious dust pollution in metallurgical enterprises. The amount of dust produced by sintering plant is large, the influence is wide, the treatment is difficult, and the harm is serious. When a 75 sintering machine, especially a m2 sintering machine, was initially put into operation, the hourly production reason was that the waste gas generated reached 3.9 × 105 RN3, scattered dust about 1.5 T. The main dust sources in the sintering production process are: ① the 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 Powder dust generated during screening of sinter; ④ Dust generated during 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

various 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 is mixed, has dust gas symbiosis. The exhaust gas has high temperature, high humidity and high dust concentration. The sinter system has a large amount of waste gas, high temperature and high dust concentration. At present, it mostly produces self fusible or high alkalinity sinter, 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 it difficult to control the sintering dust

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. It mainly includes the following aspects:

the market can be further opened only after the quality is qualified (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 reduced dust.

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

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

(4) the direct feeding mode is adopted for the tail cooling machine of the sintering machine, the hot screen at the tail of the machine is cancelled, and the cold return ore batching scheme is adopted, so as to eliminate the situation that a large amount of water vapor entrained dust is generated during the hot return ore batching

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

(6) the large-scale and automation of the sintering equipment will reduce the dust receiving personnel and the opportunity for personnel to receive dust, which is the development direction of dust prevention in the sintering plant in the future

2. Dust removal measures in sintering plant

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

(1) at present, most of the dust removal equipment in the exhaust system of sintering plant still use mechanical cyclone dust collector or multi pipe dust collector, and the purification efficiency can only reach 70 ~ 90% of the discharged dust concentration, which can not meet the national health standard. 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, is conducive to the continuous normal operation of the dust collector, centralized dust recovery and treatment, and reduces 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 powdered coke. The purification equipment adopts escs-600 linear horizontal three room wide spacing electrostatic precipitator, Mitsubishi Lurgi electrostatic precipitator and large suction back suction bag type dust collector respectively, which has achieved good dust removal effect. For the design of the electrostatic precipitator, attention is paid to the uniform distribution of air flow, the baffle plate is set in the electric field and the ash hopper, the 480mm large groove plate is used for the anode, the groove plate is set at the outlet, and the high-performance power supply is used to improve the level of the 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 transported to the sintering process system for recycling by airtight transportation or humidification

3. Sintering waste gas dedusting

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

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