For modern large-scale blast furnaces, the level of iron tapping in front of the furnace has a great impact on production. Especially in the later period of furnace service, the quality of the tapped iron not only affects the stability of the furnace, but also has a great impact on the safety and longevity of the furnace. Benxi Iron and Steel No. 5 blast furnace (2600m3) underwent extended mid-term maintenance in October 2001. At present, It has been in service for 16 years. Under conditions such as extended service, deterioration of raw and fuel conditions, and aging of equipment in front of the furnace, higher requirements have been put forward for tapping iron in front of the furnace. It has 3 tapholes, all arranged on one side. The furnace is equipped with an environmentally friendly IBNA water slag treatment system. The main iron trench is an iron storage main trench. The furnace is equipped with high-power TMT hydraulic opening machines and mud cannons. . This article starts from the progress of front-furnace tapping of Bengang No. 5 blast furnace in recent years, analyzes and summarizes some problems existing in front-of-furnace tapping:
01 In-depth management of Tiekou
The blast furnace taphole consists of the taphole frame, the furnace wall, and the mud bag near the taphole in the hearth. The depth of the taphole is the sum of the thickness of the refractory material of the taphole composite brick and the thickness of the mud bag near the taphole in the hearth. For it, the larger the volume or the deeper the dead iron layer in the hearth, the deeper the taphole depth is often required. The taphole has been exposed to the corrosion and flow erosion environment of high-temperature slag and molten iron for a long time. It is also subject to corrosion by alkali metals and damage from thermal stress. After normal operation, a large part of the brick lining at the front end of the taphole was eroded away. During the entire furnace production period, the taphole area was always protected by mud bags. As the service time continues to increase, especially in the later stages of furnace service, the depth of corrosion at the furnace bottom intensifies, the actual dead iron layer continues to deepen, and the side walls of the hearth in the taphole area are severely eroded. In order to meet the requirements for safe production of blast furnaces, the depth of the taphole must increase with the The furnace service time increases and continues to improve. In the later period of the No. 5 blast furnace’s operation, the furnace side wall temperature, cooling stave water pipe water temperature difference and heat flow intensity generally increased. Therefore, higher requirements were put forward for the depth of the taphole. The No. 5 furnace operation area formulated the pre-furnace assessment standards: 1) Iron mouth depth; 2) tap hole punctuality rate; 3) iron flow time; 4) tap hole mud blocking situation. The taphole depth is regarded as the focus of daily furnace operation, and the furnace operation technician is responsible for the task. The taphole depth is the primary indicator of the furnace assessment. The taphole depth is required to be ≥3.0m to be a qualified taphole. If the taphole depth does not meet the standard, It is necessary to analyze the reasons for the unqualified depth, and appropriately reduce the tapping time of the taphole to reduce the scouring effect of the molten iron circulation on the taphole area; unify the mud blocking amount of the three tapholes, based on the past 5 days of each taphole. The working status sets different mud plugging standards for each taphole, requiring the mud blocking amount to be ≥ 220L each time. It is forbidden to reduce mud without permission. Once discovered, strict assessment will be carried out to prevent long-term operation of the taphole that is too shallow. On-site handover will be carried out when the team takes over. Standardize the handover system.