It is not only beneficial for iron smelting to reduce silicon content in hot metal, it also has good benefit for steelmaking.. According to the statistics of many enterprises, the silicon element per 0.1% reduction, fuel ratio of 4kg/t, yield increase 5 - 7%, and are good for the stability of the furnace.. For steelmaking, to reduce the silicon element can reduce the amount of desilication reaction consumption of lime and slag quantity and improve the process of steelmaking refining effect; at the same time with the reduction of the amount of slag, smelting time is shortened and improve the productivity. Therefore, the low silicon smelting for iron and steel enterprise is imperative, is an enterprise important benefit growth point. Advancing low silicon smelting is carried out synchronously with all the blast furnace of the whole iron smelting plant.,Each blast furnace has different characteristics, the situation is not the same, some of the blast furnace itself is better, some of the blast furnace itself is equipped with a little bit. Through the mutual learning, mutual benchmarking for the gap of blast furnace, blast furnace has a different degree of progress.
we Yonggang blast furnace since may implement low silicon smelting has obvious economic benefit and the ironmaking plant daily output from the April average 19673 tons rise to 20277 tons in May, June is basically stable in more than 20700 tons, silicon by more than 0.5% dropped to 0.413%, June is basically stable at about 0.38%, grade into the furnace decreased the realized yield indicators of progress and economic benefits obvious.Steelmaking since the hot metal output increased and then gradually reduce the amount of scrap to join the monthly only reduced the cost of 10 million yuan, plus fuel to bring down the efficiency ratio of per month to reduce the cost of nearly 15 million, since the implementation of the low silicon smelting, furnace remained the smooth and stable, with a further improvement in the furnace, the indicators have progress of space.
1.2 principle of low silicon smelting: the silicon does not drop the heat, the heat loss is not reduced silicon. To achieve low silicon smelting, must do to ensure adequate hearth thermal physics, heat would undermine the airflow of the normal distribution hearth deficit, resulting in hearth disorders, fuel ratio significantly increased, operation of BF is broken.The cooling of the furnace is the cause of most of the furnace conditions, the harm caused by the furnace cooling to the blast furnace is enormous.. Therefore, low silicon smelting, you must pay attention to the hearth heat, only hearth heat abundant, in order to have a drop of silicon space to the blast furnace produce benefits.
1.3 low silicon smelting benefits: the reduction of silicon content in hot metal is not only beneficial for iron smelting, and also has a greater benefit for steelmaking. According to the statistics of many enterprises, the silicon element per 0.1% reduction, fuel ratio of 4kg/t, yield increase 0.5 - 0.7%, and are good for the stability of the furnace.. In the case of steel smelting, it can reduce the amount of lime and slag, and improve the refining effect of the process.;At the same time, with the reduction of slag amount, smelting time and productivity increase. Therefore, the low silicon smelting for iron and steel enterprise is imperative, is an enterprise important benefit growth point.
1.4 low silicon smelting measures
low silicon smelting measures:
strengthen the original fuel into the furnace management, fine material is the same topic, but also blast furnace to obtain good economic and technical indicators of the necessary conditions. What tell here concentrate not necessarily to grade into the furnace how high, coke quality how good, to reach a certain standard to concentrate, because for now, iron and steel enterprises mostly in profit or loss in operation,Upstream raw materials prices decline below the decline of steel products. Therefore, the iron and steel enterprises has not excessive pursuit of high grade into the furnace and coke quality, low cost strategy has become the pursuit direction of current steel prices, how to realize stability of BF, in case of deterioration of raw material and fuel condition, how to make comprehensive benefits maximized become enterprises in their efforts to the goal. Blast furnace, to strengthen the management of raw materials and fuel is mainly in three aspects: one is the stability of the furnace charge structure, blast furnace operation stability and change is relative, change is absolute, but stability is our pursuit of the goal. Is a stable raw material requirements of burden structure is relatively stable, not frequent adjustment,Because any kind of raw material changes will affect the soft melting zone changes, especially changes or the same proportion of the material greatly change material impact larger, late May factory blast furnace abnormal is and then sintering ore proportion greatly decreased the proportion of pellet rose sharply on. Coke, Yonggang procurement coke manufacturers, mixed breed, stockyard stacker and Reclaimer aspects still exist many problems, plus Yonggang, located in the south, frequent rain, large fluctuations in atmospheric humidity, resulting in coke actual moisture fluctuations larger, blast furnace fuel ratio greater volatility, now coke gradually realize tile straight, ingredient stability has been strengthened. Two is to strengthen the screening management,Reduce powder into the furnace. Requirements of blast furnace raw material to high, cooked, net, stability, small and uniform, the net is to emphasize the sieve net powder, by strengthening the slot sieve to reduce powder into the furnace, to Yonggang, lump ore varieties varied, sieving difficult, by increasing the vibration amplitude of the sieve, prolonged vibration feeding time, timely replacement of check the screen and to maximize the screening effect is ensured. Three is the original fuel ingredients to be relatively stable. At present, sinter composition alkalinity fluctuation is still large, especially alkalinity fluctuation, to slag basicity balance brings a big problem, resulting in frequent burden structure adjustment and stability of blast furnace can not be guaranteed.The second is material field in reactor coke problems still exist, although the realization of the tile on the approach of coke, reduce the coke from different manufacturers to bring the composition and moisture fluctuations, but the material field in to blast furnace bunker feeding did not realize direct, but stack changing frequently, resulting in high furnace fuel ratio fluctuations, temperature is difficult to control. We should strengthen the material field study and the supervision of the stacker, really provide a relatively stable raw material for blast furnace.
improve hot blast temperature, reducing coke. The wind is the most cheap energy, practice, air temperature increase for each 100 DEG C, coke rate decreased by 10 20kg/t, the yield increase, in addition,High temperature can lower the high temperature zone and decrease the height of the silicon reduction, so it is advantageous for smelting low silicon iron.. Using high temperature air can also and fuel injection combined, high blast temperature can compensation injection fuel to heat, it is beneficial to the operation of BF. At the same time, can also avoid tuyere theoretical combustion temperature is too high cause SiO formation of excessive, and ease of horizontal and vertical direction of the hearth temperature gradient, is conducive to the steady operation of furnace condition. Yonggang blast furnace air temperature is low, seven small BF air temperature only 1050-1130 DEG C, among them 1 blast furnace air temperature only 950 DEG C, 7 blast furnace air temperature although there are 1050 DEG C, but at the end of the beginning temperature up to 150 DEG C,To bring the blast furnace operation more difficult. Blast furnace air temperature is much lower than the domestic advanced level of the same type of blast furnace, resulting in high coke rate, bring some difficulties to the silicon reduction. Through optimizing the burning furnace and improve the operation, stable gas consumption, appropriate increase enriched oxygen will air temperature increase 20 - 30 DEG C, which is equivalent to reducing coke 5kg/t. Formulate reasonable upper and lower operating system, improve coal gas utilization. The operation of the blast furnace is about the stability of the furnace, the lower part is with high wind speed and the center, and the upper appropriate loose edge.. For the blast furnace, to ensure the stable operation of the economic and technical indicators, the need to center and edge of the two gas flow, to achieve the central air flow,Edge stability uniform. Too much emphasis on center or the edge is one-sided, especially small blast furnace, peripheral big fluctuations in raw material condition, must be to ensure the air flow center based on appropriate loose edge, otherwise the edge overweight easily lead to collapse even suspended material, edge of the light and easy to cause fluctuations in furnace conditions, fuel ratio increased. After several blast furnace material adjustment, at present, several blast furnace basic achieved stable, the index also has some improvement. Send wind system as far as possible the request tuyere equal length and diameter, tuyeres length should not be less than 5% of the diameter of hearth, edge airflow uneven first when adjusting tuyere diameter, secondly adjusting tuyere length.From the present situation, a factory blast furnace outlet adjustment is not much, the length of the two plant blast furnace is obviously shorter, there is a chance to adjust the wind opportunity.
increasing slag basicity, guarantee the mg / Al ratio. Reasonable slagging system is a necessary condition for reducing silicon, maintain high basicity of slag for low silicon smelting favorable. Because with the increase of basicity, slag of Cao and SiO2 is easy to generate 3CaO.SiO2 and 2 CaO.SiO2 and other compounds that reduce the dropping zone of middle slag activity, inhibit the reduction of silicon. In addition, with the increase of alkalinity, the physical heat of hot metal is increased, which is beneficial to slag desulfurization and the reduction of silicon.. Considering the conditions surrounding the frequent fluctuations of steel,To stabilize the furnace condition brings adverse effect, binary alkalinity should not be too high, will be inevitable because of the higher alkalinity needs a higher heat, blast furnace and silicon reduction process appear to lose heat and heat to reduce the greatest harm in slag fluidity and desulfurization effect becomes worse, once the external conditions change on a large scale relief is not timely, easy to cause the condition of hearth, to the stability of BF brings adverse effects. And appropriate to increase the MgO content in slag, ensure that the mg / Al ratio, not only can ensure the effect of slag desulfurization, improve the fluidity of the slag, ensure the quality of pig iron. From the current practice of smelting, mg / Al ratio should be maintained at more than 0.65,The upper limit is not higher than 0.8%, in order to avoid the high MgO caused the sintering ore cost rise and the quality fall.
enhancing top pressure. The gas flow rate is decreased, gas flow rate of gas is prolonged, and the gas utilization rate can be improved when the pressure is raised.. At the same time, the can inhibit the direct reduction of SiO2 (SiO2---SiO CO2 C), and reduce the generation of SiO gas, which can be decreased to some extent.. Before Yonggang small blast furnace top pressure is low, about only 140Kpa. Now, has been increased to 145 - 150kPa, not only to solve the blast furnace in the lower grade into the furnace permeability of the problem of poor, to ensure the incoming heat flow stability,And to some extent, it also plays a role in promoting the silicon.. But the top pressure use, plant a few blast furnaces met some problems. 4 blast furnace bullied secret compartment influence top pressure is low, only 115Kpa, plant a three seat above of the same type of blast furnace low 30KPa, which makes the blast furnace was forced to adopt tuyere drop low dropout, edge of air blast furnace control caused a certain influence. 5 - 7 blast furnace furnace service to the late, the hot air system has hidden trouble, the wind pressure within the limits of 280KPa, but also to blast furnace with wind caused a certain impact. The implementation of temperature trend management
. The temperature trend of management is a difficult problem in blast furnace operation.The so-called trend of management is to the current situation and development trend of the temperature effect of all kinds of factors, including the cause and effect of time, tuyere status changes, temperature, amount of motion direction and effect and so on, comprehensive analysis and judgement, according to temperature changes in trends, pre adjustment heat levels. Rather than on the current situation of furnace temperature (now the Si level) regulating temperature, which can reduce the temperature fluctuations, to early less dynamic effect. If not according to the temperature trend of management, only by the current Si or the temperature of the molten iron to adjust the temperature occurs behind the temperature change and overhead heating or hot temperature caused by continuous reduction of heat caused by temperature sharply to cool.The temperature of big wave landing.
1.5 in the actual production of
the current Si or the temperature of molten iron is reflected in the result of previous smelting process of thermal equilibrium, although the reference value of judgment on the temperature, but can not do basis for regulating temperature. Because the blast furnace operation has a thermal inertia, furnace temperature is along with the changes of various factors are evolving, the current temperature cool stove may is to heat, may also continue to cool, the current furnace heat stove may has to cool, may also continue to heat, if only in accordance with the current temperature regulating temperature, it may lag behind the development trend of temperature, and the direction is unknown in regulating temperature.Often will only aggravate the temperature fluctuation. And for Yonggang blast furnace, blast temperature low, large fluctuations of raw materials and fuel, coupled with the southern weather changes moisture changes, foreman operation level is limited, workshop management is not in place and other conditions, resulting in temperature fluctuation is large, and the emergence of the fluctuation of the roller coaster, low temperature, foreman to reduce wind freely and the magnitude is too large, upward trend in the temperature when foreman and the wind not promptly, but adjusted according to the actual temperature of the furnace tapping and operation delay caused by temperature sharply upward; at high temperature, reducing coal for a long time, temperature trend has been downward adjustment is not in place, is also the root according to actual tapping temperature transfers,Caused by the adjustment lag, temperature decreased a lot, so repeatedly, resulting in temperature a roller coaster fluctuations, airflow in furnace stability caused great difficulties to, or to adversely affect the progress indicator. Foreman should abandon the use of air temperature adjustment, the wind full oxygen operation, reduce wind reduction times, once the temperature is too low or physical heat below the lower limit of visual control of the wind, often see tuyere, the upward trend in a timely manner with the wind to minimize losses.
effect of temperature of many factors, such as raw material and fuel condition, air temperature, furnace grade, rain and snow weather, swap operations, the smooth operation of furnace condition and so on. For large raw fuel changes,Such as sintering ore proportion reduced, together with a great deal to eat ground ore, raw ore ratio increased and, easy to cause the coke ratio increased, this time to in a timely manner to reduce the load; for rain and snow weather, the coke moisture changes to timely adjustment. In addition due to the air humidity increases, resulting in actual furnace volume increased, feed speed, this time also should be according to the running situation timely control of oxygen, prevent super smelting caused by lowering temperature. Foreman must be ye strong notions and 8 hours to run three classes are basically stable, the super smelting of great harm, extremely easy to cause temperature drops, the control is not good will cause cooling of the furnace. Therefore, the foreman in operation to always pay attention to the hour of feeding speeds,It is necessary to reduce the load when the material is continuous and exceed the normal speed. It is necessary to ensure the stability of the smelting and smelting by controlling the oxygen reduction material speed..
improve the foreman level of operation, the implementation of sophisticated operation. To achieve a better economic and technical indicators, we must strengthen the fine operation, the quantification of things to quantify as much as possible, to reduce random operation. For a long time, Yonggang of blast furnace foreman to minus the wind operation as a means of daily temperature control, low temperature reduced in random wind, and reduced number of wind is free, no specific quantitative criteria,
strengthen equipment spot inspection maintenance, reduce unplanned downtime and slow wind.
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