Plant-based observations. The tap-hole area of Furnace A was in a much better condition than that in Furnace B, as seen in Figure 4a compared to Figure 4b. The photographs in Figure 4 were taken after removal of the tap launders. At both SAFs, the quick-replaceable carbon blocks were installed in an area referred to as the chapel, which was named after the shape of the protective heat shield around this area. In Figure 4 , parts of the steel shells of the protective heat shields are clearly visible as the refractory materials which cover them during operation were removed by the time the photographs were taken.
In Figure 4a the rubble generated during the removal of the launder and the refractory from the protective heat shields is still visible. The quick-replaceable carbon blocks on both SAFs had very large, oval-shaped tap-holes as seen in Figure 4. For each SAF, the oval-shaped tap-hole appeared to consist of two distinct tap-holes, as is clearly visible in Figure 4a. Below the quick-replaceable carbon block a third 'tap-hole' was visible, again seen more clearly in Figure 4a. These observations indicate that even though the tap-hole design philosophy was based on one single-level tap-hole, normal operations require two tap-hole levels and emergency operations a third.
Therefore the tap-hole life-cycle Steenkamp et al. Furnace designers will probably argue that operations were not conducted properly, but these two SAFs were operated by two different operating crews and the fact that the observation was made on both SAFs is probably an indication that tapblock life could be improved by a design that allows for the need for three tap-hole levels. The dimensions of the quick-replaceable carbon blocks were determined by measuring tape, and those of the oval-shaped tap-hole by dimensional analysis see Figure 5.
In Figure 5a the long end of the block is in a horizontal position and in Figure 5b in a vertical position. The deviation is attributed to the tapblock wear in Furnace B being much more significant than in Furnace A, as can be seen in Figure 6. Upon removal of the quick-replaceable carbon blocks, very little of the original tapblock remained for Furnace A Figure 6a and none for Furnace B Figure 6b.
The areas where the tapblocks were supposed to be were filled with process material. In Furnace A Figure 6a , the process material consisted mainly of coke bed, in other words slag and carbonaceous reductant. In Furnace B Figure 6b , the process material consisted of a coke bed and tap-hole clay mixture towards the top and alloy at the bottom. In Figure 6b , the tap-hole clay used to plug the tap-hole is clearly visible. For Furnace A, a wear profile of the refractory surrounding the tapblock could be determined by manual measurement once the refractory around the tapblock cooled, allowing access.liraschabipo.ml/mac-os-x-icons-rocketdock.php
Handbook of Ferroalloys: Theory and Technology
Measurements were done using a tape measure and the results were superimposed onto the design drawing - see Figure 7. The wear observed was probably a result of a combination of sidewall refractory wear associated with each of the clovers and wear associated with the tapping of liquid slag and alloy through the tap-hole and associated lancing activities. For Furnace B, a wear profile could unfortunately not be determined due to time constraints. Thermodynamic calculations. In the sections below, the phase distributions for specific conditions are presented as a function of temperature.
The conditions were alloy or slag on their own, and slag or alloy in combination with C or SiC refractory.
Would you like to see more like this?
In Figure 8 , the results for alloy and slag only are presented. As the temperature increases, the liquid slag phase increases as expected. The slag:spinel ratios for Slag 1 and Slag 3 are very similar over the temperature range, ranging between 2. For Slag 2, the ratio is higher over the temperature range and ranges between 3. The lower spinel content in this slag is expected due to the absence of spinel-forming Cr and Fe. In Figure 9 , the results for alloy in contact with refractory are presented. For alloy in contact with C-based refractory, three phases are present: the C-based refractory, the liquid alloy, and an iron-containing chrome carbide with an increased carbon content metal-cation-to-carbon ratio is 1.
The slight reduction in the amount of C-based refractory is either due to the formation of Cr, Fe 3 C 2 or to solution into the liquid alloy. For alloy in contact with SiC-based refractory, only two phases are present: the SiC-based refractory and the liquid alloy. In the temperature range under investigation, the reduction in the amount of SiC-based refractory is due to solution into the liquid alloy.
From these results, it can be concluded that two potential corrosion mechanisms apply: chemical reaction or dissolution, described by the following three chemical reactions:. M depicts species present as a liquid phase.
- Shop now and earn 2 points per $1.
- The Other Winfrey.
- Handbook of Ferroalloys - 1st Edition.
- Can You Forgive Her? (Palliser, Book 1).
- My Wishlist.
- Handbook of Ferroalloys: Theory and Technology by Michael Gasik, Hardcover | Barnes & Noble®.
M depicts species in solution. M depicts species present as a gas phase. In Figure 10 , the results for slag in contact with C-based refractory are presented. For all three slags, spinel and liquid slag phases are present in the temperature range under investigation. Interestingly enough, the slag:spinel ratio initially increases and then decreases with temperature in all three instances. The amount of SiC formed is greatest for Slag 2 see Figure 10b. In the slags with Cr and Fe present Slag 1 and Slag 3 , liquid alloy forms in the temperature range under investigation.
For Slag 3, the iron-containing chrome carbide with metal-cation-to-carbon ratio of 2. From these results, it can be concluded that one potential corrosion mechanism applies: a chemical reaction - described by Equations  to :. In Figure 11 , the results for slag in contact with SiC-based refractory are presented. The liquid slag phase is present in all three cases in the temperature range under investigation.
Gas also forms in increasing amounts as the temperature increases. From these results, it can be concluded that one potential corrosion mechanism applies: chemical reaction, described by Equations  and  above, and Equations  and :. From the results presented in Figure 9 , the main corrosion mechanism responsible for the wear of C- or SiC-based refractory by FeCr alloy is the dissolution of the refractory into the alloy.
As can be seen in Figure 12 , the potential for SiC-based refractory to dissolve into alloy is greater than for C-based refractory. From results presented in Figure 10 and Figure 11 , the main corrosion mechanism responsible for the wear of C- or SiC-based refractory by FeCr slag is chemical reaction. For Slag 1 and Slag 3, both alloy and SiC formation apply.
In alloy formation, dissolution of the spinel phase into the slag to supplement the CrO and FeO, reduced according to Equations  to , plays a role. To what extent the reaction kinetics will allow for the dissolution to occur during tapping is a matter for further investigation. To what extent lancing affects the temperature and slag composition in the tapblock, and how this contributes to the mechanisms observed, will be interesting to understand.
The results presented here do not explain the difference, and a similar study on the potential effect of refractory corrosion by gas phases present in fully enclosed SAFs will be useful. For the alloy, the main mechanism is related to dissolution of C or SiC into the alloy.
For slag, chemical reactions between CrO, FeO, and SiO 2 in the slag and refractory are the main mechanisms with alloy, SiC, and gas the reaction products formed. The support of management and personnel at a South African producer of ferrochrome and colleagues from Mintek who assisted with observations, measurements, and sampling on shift is gratefully acknowledged. The author further would like to acknowledge valuable inputs and discussions with Markus Erwee. This work is published with the permission of Mintek. Bale, C. Barker, I. Measurement and control of arcing in a submerged-arc furnace.
Indian Ferro Alloy Producers Association. High carbon ferrochrome technology. Handbook of Ferroalloys - Theory and Technology. Butterworth-Heinemann, Oxford, UK. Chapter 9. Bergmann, C. Using mineralogical characterisation and process modelling to simulate the gravity recovery of ferrochrome fines. Minerals Engineering, vol. Coetzee, C. Campaign extensions for ferroalloy furnaces with improved tap hole repair system.
Outotec Oyj. New refractory lining direction at Jindal Stainless FeCr 1 and 2 furnaces. Duncanson, P. The truths and myths of freeze lining technology for submerged arc furnaces. Reynolds, Q. Comparison of 2D and 3D computational multiphase fluid flow models of oxygen lancing of pyrometallurgical furnace tap-holes. JOM, vol. Technology of chromium and its ferroalloys. Chapter 8. Hancock, J.
Practical Refractories. Hubble, D. Steel plant refractories. Inada, T. Dissection investigation of blast furnace hearth-Kokura no. ISIJ International, vol. McDougall, I.
The biggest internet trends, by email
Ferroalloys processing equipment. Handbook of Ferroalloys -Theory and Technology. Chapter 4. Nelson, L. The tap-hole - key to furnace performance. Pariser, H. Changing nickel and chromium stainless steel markets - Market review by Heinz Pariser. Insulating or conductive lining designs for electric furnace smelting? Steenkamp, J. Dissipation of electrical energy in submerged arc furnaces producing silicomanganese and high-carbon ferromanganese. Insights into the potential for reduced refractory wear in silicomanganese smelters.
Tap-hole life cycle design criteria: A case study based on silicomanganese production. Correspondence : J. Steenkamp Email: joalets mintek. Received: 14 Mar. All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License. Services on Demand Article. English pdf Article in xml format Article references How to cite this article Automatic translation. Access statistics. Cited by Google Similars in Google.
- The Big Parade and American World War I Film Genre.
- Junkers Ju 88 Kampfgeschwader on the Russian Front (Combat Aircraft)?
- [PDF] Download Handbook of Ferroalloys: Theory and Technology Full Kindle - Video Dailymotion.
- SECURITY ENTERPRIZE.
Introduction Ferrochrome FeCr is an essential alloy in the production of stainless steel Gasik, Background Refractory wear mechanisms associated with the tap-hole region The refractory wear mechanisms reported in the literature for SAFs are densification, spalling, erosion, and corrosion. Refractory design The SAFs under investigation were of circular design, with inner diameters of the steel shells at Tapping practice With the furnaces having only one single-level tap-hole, slag and alloy were tapped simultaneously.
[PDF] Edition Handbook of Ferroalloys Theory and Technology PDF books
Like this presentation? Why not share! Embed Size px. Start on. Show related SlideShares at end. WordPress Shortcode. Published in: Education.
Full Name Comment goes here. Are you sure you want to Yes No. Be the first to like this. No Downloads. Views Total views. Actions Shares. Embeds 0 No embeds. No notes for slide. If you want to download this book, click link in the next page 5.
Related Handbook of Ferroalloys. Theory and Technology
Copyright 2019 - All Right Reserved