Research On The Long Comapign Practices For The Blast Furnaces Of JISCO

Because of the highest heat utilization rate and production efficiency,blast furnaces are the most efficient ironmaking equipments in the forseeable furure.The production cost and energy consumption of BF iron-making accounts for about 70%of the cost of iron and steel enterprises,and the cost of overhaul and intermediate repair of blast furnace are very high,so it is important to achieve long campaign,safety and high efficiency production during the blast furnace service period for the iron and steel enterprises.Based on the production practice,experience and data of JISCO’s blast furnace for many years,the design,construction,operation and maintenance technology are analyzed comprehensively in this paper.Furthermore,through the application and practice of No.1 and No.2 blast furnace overhaul in 2013,the direction of long campaign of blast furnace in JISCO was summarized.The main results are as follows:(1)Based on the design concept of "smooth operation is long campaign",the characteristics of raw materials and fuels with low grade,high slag ratio and harmful elements content in JISCO are fully considered to further reduce the ratio of height/diameter and deepen the molten iron layer so as to adapt to the characteristics of raw materials.In this campaign,No.1 and No.2 blast furnace achieve the active hearth,the reasonable gas flow distribution,the enhanced ability for resisting peripheral change,and the blast furnace smooth operation is obviously improved.(2)In order to solve the problem of short service life of cooling stave at the stack,belly and bosh of blast furnace in JISCO,some new technologies,such as copper cooling stave,brick wall in one,thin wall lining and soft water closed circulation,were adopted in the overhaul design of No.1 and No.2 blast furnaces in JISCO.The ceramic cup and water-cooled carbon brick structure was adopts for hearth,the large composite brick were adopt at tuyere area,the Si3N4SiC brick were adopts for bosh and belly area,and the shell material quality is improved from Q235-B to Q345-C.During the furnace construction,the construction quality was strictly controlled.The production practice proves that the wall temperature of No.1 and No.2 blast furnaces is homogeneous,the cooling equipment works stably and the shell temperature is normal.(3)The analysis shows that the low grade of ore,the high alkali load and zinc load of blast furnace lead to the difficulty of operation and the low smooth operation of blast furnace,which is the main factor caused the short service life of blast furnace of JISCO.Therefore,since 2013,JISCO has implemented the concentrated burden technology to improve the charge grade,optimize the burden structure with high basicity sinter,and strictly control the harmful elements load and its influence on the production of blast furnace.Adhere to the full-open tuyere operation in production,constantly optimize the air supply system and charging system,to form a suitable distribution of gas flow and reduce the furnace body heat load.The production practice of No.1 and No.2 blast furnaces indicate that the "alkali damage" and furnace condition abnormality were controlled,and the operation difficulty was greatly reduced.The operation system and operation technology with the characteristics of JISCO’s blast furnace were formed.(4)After years of development and practice,JISCO has mastered the daily maintenance and repair technology,such as smelting with vanadium titanium ore,cooling stave repair,hard indentation lining,furnace body gunning,which provides effective technical support for JISCO to prolong campaign of blast furnace.Since the start-up of the new compaign,the cooling equipment fo BF has not been damaged,and the performance has been improved obviously.The technical index has been improved,the cost of pig iron has been reduced,the operation environment has been improved,and the furnace body has been running well.This campaign is expected to achieve non-intermediate repair,utilization factor of more than 2.1.t/m3·d and iron output of more than 15 000 t/m3 per unit furnace capacity.Overall,the new campaign of No.l and No.2 blast furnace represent the highest level of blast furnaces design and production in JISCO,and the long campaign technical system which suitable for JISCO blast furnace have been formed.