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Use of Oxygen-Enriched Gas for the Oxidation of Acid and Fluxed Taconite Pellets

By Haas, Larry A.

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Book Id: WPLBN0000110083
Format Type: PDF eBook:
File Size: 3.49 MB
Reproduction Date: 2005

Title: Use of Oxygen-Enriched Gas for the Oxidation of Acid and Fluxed Taconite Pellets  
Author: Haas, Larry A.
Volume:
Language: English
Subject: Health., Medical research, Medical reports
Collections: Medical Library Collection
Historic
Publication Date:
Publisher: Centers for Disease Control and Prevention

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APA MLA Chicago

A. Haa, B. L. (n.d.). Use of Oxygen-Enriched Gas for the Oxidation of Acid and Fluxed Taconite Pellets. Retrieved from http://www.gutenberg.cc/


Excerpt
The U.S. Bureau of Mines, in cooperation with Cleveland-Cliffs, Inc. (Hibbing, MN), investigated ways of enhancing the quality (compressive strength, after-tumble and reducibility) of domestic acid and fluxed magnetite pellets by m o d i g the oxygen content during the preheat and induration periods of the firing operation. Oxidation of magnetite was best accomplished when sufficient oxygen and time were available before the peak induration temperature was reached. The rate of magnetite oxidation increased directly with the gas oxygen content during the preheat period at 700' C and above. With 30 pct (or more) 0, and a preheat rate of 200 C/min, most of the magnetite was oxidized during the preheat period. With laboratory tube and mini-pot furnace tests, oxygen enrichment during the preheat period improved the pellet properties more in the simulated grate-kiln tests than in the simulated straight-grate tests. The longer induration period with the grate-kiln test resulted in more sintering of the residual magnetite and its reaction with the silicon compounds. When flux was present in the pellets, calcium silicates and calcium and magnesium ferrites were formed. More calcium ferrite was formed when the magnetite was oxidized early and less iron was present in the fatality calcium silicate slag.

Table of Contents
CONTENTS Page Abstract ........................................................................... Introduction ........................................................................ Status of pellet fuing technology ....................................................... Oxidation and sintering mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgment .................................................................... Materials .......................................................................... Experimentaltechniques ............................................................... Thermogravimetric furnace pellet procedures ............................................. Isothermal oxidation method ....................................................... Programmed temperature method .................................................... Platinum basket reduction method ................................................... Mini-pot pellet procedures ........................................................... Pellet microstructure analysis procedure ................................................. Experimental results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thermogravimetric isothermal oxidation findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Therrnogravimetric programmed temperature oxidation findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acid pellet oxidation studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pre- and postinduration oxidation experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preheat oxygen experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fluxedpelletstudies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pre- and postinduration oxidation experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preheat oxygen experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mini-pot pellet oxidation findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Preheat ferrous content studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Two-minute induration studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acid pellet experiments ......................................................... Fluxed pellet experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thirty-minute induration studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acid pellet experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fluxed pellet experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reductionfindings ................................................................. Acidpelletstudies ............................................................... Fluxed pellet studies .............................................................. Pellet microstructure findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusions .................................

 
 



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