Development of Smelting Reduction Processes for Ironmaking Mar08

Development of Smelting Reduction Processes for Ironmaking...

Development of Smelting Reduction Processes for Ironmaking Smelting reduction (SR) processes are the most recent development in the production technology of hot metal (liquid iron). These processes combine the gasification of non-coking coal with the melt reduction of iron ore. Energy intensity of SR processes is lower than that of blast furnace (BF), since the production of coke is not needed and the need for preparation of iron ore is also reduced. SR ironmaking process was conceived in the late 1930s. The history of the development of SR processes goes back to the 1950s. The laboratory scale fundamental studies on the SR of iron ore were started first by Dancy in 1951. However, serious efforts started from 1980 onwards. There have been two separate lines of development of primary ironmaking technology during the second half of twentieth century. The first line of development was centred on the BF which remained the principal process unit for the hot metal production. In general, this line of the development did not encompass any radical process changes in the furnace itself. It proceeded through a gradual evolution which involved (i) increase in the furnace size, (ii) improvement in the burden preparation, (iii) increase in the top pressure, (iv) increase of hot blast temperature, (v) bell-less charging and improvements in burden distribution, (vi) improvements in refractories and cooling systems, (vii) injection of auxiliary fuels (fuel gas, liquid fuel, or pulverized coal) and enrichment of hot air blast with oxygen (O2), and (viii) application of automation as well as improvements in instrumentation and control technology. The continued success of the ironmaking in BF reflects the very high levels of thermal and chemical efficiencies which can be achieved during the production of hot metal and the consequent cost advantages. In fact,...

Probes, Instruments and measurements for Monitoring of Blast Furnace Jun28

Probes, Instruments and measurements for Monitoring of Blast Furnace...

Probes, Instruments and measurements for Monitoring of Blast Furnace A blast furnace (BF) works with the principle of countercurrent gas to solid heat exchange from tuyere raceway to the stock line and of a countercurrent oxygen (O2) exchange from fusion zone to the stock line. Solid burden materials consisting of ferrous materials (iron ore, sinter, and pellets), coke, and fluxing materials are charged into the top of the furnace, while air normally enriched with O2, and sometimes with auxiliary fuels is fed through the tuyeres near the bottom of the furnace. The usual retention time of the ferrous burden materials in the furnace may be as long as 8 hours, while that of the gas is a few seconds. However, the residence time of the coke in the hearth is much longer usually ranging from 1 week to 4 weeks. The liquid hot metal (HM) and liquid slag are tapped at regular intervals through a number of tapholes situated at the bottom of the furnace. The slag is separated from the hot metal which is handled through HM ladles. A blast furnace need to be operated with high productivity and low fuel rate in a flexible, stable and high efficiency manner and must have a long campaign life. The blast furnace is often referred to as black box because of the terms such as the furnace condition and furnace heat level which is currently in dominant use as well as since the blast furnace process has many unknown areas. The reason seems to be due to the difficulty in measurement, because, in a blast furnace, three phases of gas, solid, and liquid coexist, the reaction proceeds non-uniformly in radial direction, the process is accompanied by a time dependent variation, and the parameters to be...

Blast Furnace Tuyeres and Tuyere Stocks May29

Blast Furnace Tuyeres and Tuyere Stocks...

Blast Furnace Tuyeres and Tuyere Stocks The blast furnace (BF) has the objective of extracting the hot metal (liquid iron) from iron ore lump, sinter and/or pellet, coke and injected fuel. This objective is achieved by passing a hot enriched air flow (hot blast air) through the ore and coke burden which goes down in the internal column of the BF. The hot blast air and auxiliary fuel are injected into the blast furnace through tuyeres located around the perimeter of the BF. The upper zone of the hearth wall of the blast furnace contains the openings for the tuyeres which are used to introduce the hot blast air into the furnace. The furnace jacket in the tuyere zone contains steel reinforced openings within which copper (Cu) cooled elements are installed, similar to that shown in Fig 1. The steel reinforcements in the jacket are called tuyere cooler holders. The large Cu cooler which is installed within the machined inner surface of the cooler holder is called the tuyere cooler. The Cu cooler which actually introduces the hot blast air into the furnace is called the tuyere. It is installed within a machined, inner seating surface on the tuyere cooler. The blowpipe is part of the tuyere stock air distribution piping, which delivers the hot blast air from the bustle pipe, and which mates with the tuyere, to direct the hot blast air into the furnace. The tuyere breast walls are usually made of carbon brick and the cooling is generally external with jacketed cooling channels on the outside of the shell. Some furnaces have internal staves in the tuyere breast between the tuyere coolers as a cooling design for the tuyere breast. Fig 1 also shows the arrangement of the tuyere cooler holder,...

Blast Furnace Cast House Equipments May16

Blast Furnace Cast House Equipments...

Blast Furnace Cast House Equipments The cast house floor of a blast furnace has always been one of the most dangerous working places in a blast furnace. Apart from working in an atmosphere which includes toxic gases, fumes, and dust, the operators have to perform hard and heavy manual work close to hot metal and slag runners and ladles filled with hot metal. Before the invention and installation of cast house equipment, the tapholes were opened and closed manually. Opening was done by means of steel bars and sledgehammers, whereas the taphole was closed by repeatedly ramming small amounts of clay or refractory material into the taphole, again with the help of long, heavy bars. In addition, on blast furnace, the blast had to be stopped, since it was impossible to close the taphole properly against the blast furnace pressure. This stoppage of the blast resulted in regular losses of production. Samuel W. Vaughen of USA invented the first mud gun in 1895. His pneumatic mud gun machine operated with steam, had a detachable nozzle that had to be swung open to load the taphole mass. In 1901 there was another big change in taphole practices when Ernst Menne of Germany invented the oxygen lance. By blowing oxygen through a 1/8 inch pipe and igniting it, it was now possible to open the taphole very quickly compared to the pure manual method. The first records of taphole drills is found around 1921 when Edgar E. Brosius and Joseph E. Judy of USA suggested a method of drilling the taphole for its opening. Brosius even invented a combined drilling and lancing apparatus in 1924. An excellent cast house setup is an important necessity for a low cost, high productivity blast furnace since an effective operation...

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...