Importance of Hearth, Dead man and Tapping in Blast Furnace Operation Apr13

Importance of Hearth, Dead man and Tapping in Blast Furnace Operation...

Importance of Hearth, Dead man and Tapping in Blast Furnace Operation  A trend of deterioration in ore quality is seen these days with the increasing demand for iron ore. The deterioration in ore quality is accompanied with higher quantities of slag which in turn affects burden descent and liquid flow through the hearth. These conditions provide a catalyst for lining wear mechanism with bosh, stack and hearth linings coming under additional stress. Tapping in the blast furnace is adversely affected and trough and runners in the cast house get under strain due to higher slag volume. All these put increased pressure on blast furnace operations. The poor quality of iron ore affects the operation of the blast furnace in the following way. Slag volume – Poor quality of iron ores bring into the furnace higher quantities of impurities resulting into increase in the slag volumes. Heat load – The furnace thermal condition undergoes changes since a large quantity of heat is required to melt the additional slag as well as to keep it in proper fluid state for its drainage. This introduces higher heat loads inside the blast furnace. Coke rate and productivity – Increasing slag volumes needs a higher fuel input into the furnace, and where pulverized coal injection rates are already running at optimum, this results into a higher coke rate. Higher coke means introduction of higher amount of ash in the furnace resulting into further increase in the slag volume. This has got a deteriorating effect on the productivity of the furnace. Process stability – The deterioration in the ore quality affects the process stability adversely and has an unfavourable effect on the smooth running of the blast furnace. Due to the above factors, the production process in the blast furnace...

Salamander Tapping for Capital Repairs of Blast Furnace Aug26

Salamander Tapping for Capital Repairs of Blast Furnace...

Salamander Tapping for Capital Repairs of Blast Furnace  A salamander means all liquid and solidified materials in the hearth of a blast furnace below the tap hole. The salamander includes liquid iron and slag and mixtures of solid iron, slag and coke/carbon. During the normal operation of the blast furnace, the furnace bottom and hearth contains the ‘dead-man’ and the salamander. When the blast furnace is to be relined, it is necessary that the furnace is emptied completely by removing all the constituents of the bottom and the hearth. It is also desirable to remove these constituents during partial relining of the furnace or during the repairs of the tap-hole. This provides safer working conditions during these partial repairs and prevents damage to the hearth refractories as a result of cyclic cooling and heating movements. The removal of all the constituents of the bottom and the hearth of the furnace is carried out usually by salamander tapping. The salamander tapping is usually done at preferably the lowest level where liquid iron can be expected in the blast furnace hearth. Salamander tapping of a blast furnace is the final tapping after the furnace is blown down in order to drain the last liquid iron from the furnace hearth. Because of its rare occurrence a salamander tapping represents in most of the steel plants a specialized job which requires a lot of preparation. A solidified salamander is normally difficult to remove especially if there is titanium in it. A large quantity of solid salamander can delay the critical path of the capital repairs of the blast furnace by a number of days or even by weeks. For the removal of the solidified salamander often requires oxygen lancing and even explosives. These types of removal also cause health and safety...

Improved Designs  and Campaign Life of a Blast Furnace May23

Improved Designs and Campaign Life of a Blast Furnace...

Improved Designs  and Campaign Life of a Blast Furnace The cost of rebuilding or relining a blast furnace (BF) is very high. Hence techniques to extend BF campaign lives are important and need to be pursued very actively. Large BFs usually have a slightly higher campaign output per unit volume. This difference is because larger BFs generally are of more modern design and are well automated.  Since the viability of an integrated steel plant depends on a continuous supply of hot metal (HM), which, in a plant with a small number of large BFs, puts great importance on long campaign life. The techniques for prolongation of BF campaign life falls under the following three categories. Operational practices – The control of the BF process has a major effect on the campaign life. BF is to be operated not only for meeting the production needs but also to maximize its life. Hence it is necessary to modify operating practices as the campaign progresses and in response to the problem areas for the maximization of campaign life. Remedial measures – Once wear or damage that affects the life of the BF becomes evident, engineering repair techniques are to be used or developed to maximize campaign life. Improved designs – As improved materials and equipment are developed, these are to be incorporated into future rebuilds to extend the life of critical areas of the BF, where it is cost effective to do so. Improved designs of the BF for improving the campaign life are discussed in this article. The correct design of the furnace proper is fundamental to reliable operation, metallurgical performance, sustained high productivity, long campaign life and an availability of more than 98 %. BF design has had many improvements in recent decades and campaigns...

Remedial measures and Campaign Life of a Blast Furnace May17

Remedial measures and Campaign Life of a Blast Furnace...

Remedial measures and Campaign Life of a Blast Furnace  The cost of rebuilding or relining a blast furnace (BF) is very high. Hence techniques to extend BF campaign lives are important and need to be pursued very actively. Large BFs usually have a slightly higher campaign output per unit volume. This difference is because larger BFs generally are of more modern design and are well automated.  Since the viability of an integrated steel plant depends on a continuous supply of hot metal (HM), which, in a plant with a small number of large BFs, puts great importance on long campaign life. The techniques for prolongation of BF campaign life falls under the following three categories. Operational practices – The control of the BF process has a major effect on the campaign life. BF is to be operated not only for meeting the production needs but also to maximize its life. Hence it is necessary to modify operating practices as the campaign progresses and in response to the problem areas for the maximization of campaign life. Remedial measures – Once wear or damage that affects the life of the BF becomes evident, engineering repair techniques are to be used or developed to maximize campaign life. Improved designs – As improved materials and equipment are developed, these are to be incorporated into future rebuilds to extend the life of critical areas of the BF, where it is cost effective to do so. Remedial measures for improving the campaign life of the BF are discussed in this article. The measures which are normally adopted for improving the campaign life of BF are described below. Cold repairs and gunniting repair The stack refractory brick work is usually exposed to mechanical wear in the upper part and also to...

Operation practices and Campaign Life of a Blast Furnace May11

Operation practices and Campaign Life of a Blast Furnace...

Operation practices and Campaign Life of a Blast Furnace The cost of rebuilding or relining a blast furnace (BF) is very high. Hence techniques to extend BF campaign lives are important and need to be pursued very actively. Large BFs usually have a slightly higher campaign output per unit volume. This difference is because larger BFs generally are of more modern design and well automated.  Since the viability of an integrated steel plant depends on a continuous supply of hot metal (HM), which in a plant with a small number of large furnaces puts great importance on long campaign life. The techniques for prolongation of BF campaign life (Fig 1) falls under the following three categories. Operational practices – The control of the BF process has a major effect on the campaign life. BF is to be operated not only for meeting the production needs but also to maximize its life. Hence it is necessary to modify operating practices as the campaign progresses and in response to the problem areas for the maximization of campaign life. Remedial actions – Once wear or damage that affects the life of the BF becomes evident, engineering repair techniques are to be used or developed to maximize campaign life. Improved designs – As improved materials and equipment are developed, these are to be incorporated into future rebuilds to extend the life of critical areas of the BF, where it is cost effective to do so.   Fig 1 Techniques for prolongation of blast furnace campaign life Operational practices for improved campaign life are discussed in this article. The operating practices affecting the BF campaign life are described below. Productivity The productivity of a BF is normally expressed in tons (t) of HM per unit BF volume (cum) per...