DEPHOSPHORIZATION OF AGBAJA IRON ORE BY HYDROMETALLURGICAL METHOD

AUTHOR: ONWUBIKO, OBIORAH SAMUEL MARY KEVIN 

DEPARTMENT: METALLURGICAL AND MATERIALS ENGINEERING

AFFILIATION: NNAMDI AZIKIWE UNIVERSITY, AWKA

The research studied the dephosphorization of Agbaja iron ore to enable its utilization in iron and steel production. The ore contains 1.4 to 2.0%phosphorus which is beyond the acceptable limit of 0.08% for tradedable steel and 0.045% for engineering applications. Beyond 0.045% Phosphorus content, cold shortness is imparted to the steel due to formation of brittle phases with iron. The digestion technique was adopted for the research using sulphuric, hydrochloric and citric acids either separately on in various combinations. One Factor at a Time (OFAT) was initially used to apply leachants and other crucial factors to effect dephosphorization. Due to the deficiency of the technique, Design of Experiments (DOE) technique was resorted to because it enables simultaneous determination of individual and interactive effects of many factors on the response variable in designs. DOE also provides a full insight to the interaction between the design elements and helps to isolate the sensitive parts and areas that cause in yield. 23 full factorial designs of experiments with response surface methodology were used to determine the main factor effects, the interaction effects and optimization at different factor levels. In the use of sulphuric acid, best result occurred at levels of concentration of 1.0M, 20 minutes dwell time and 0.4mm particle size and the degree of dephosporous reached 96%. In the case of hydrochloric acid, best result occurred at concentration 1.0M, dwell time 30mins and 0.4mm particles size and degree of Dephosphorization reaching 94%. In the case of two acid mixtures, at concentration of 1.0M, dwell time of 20mins and 0.4mm particle size range with degree of Dephosphorization reached 98% and this exactly fits well with the set target. In the case of 3 acid mixtures the degree of Dephosphorization reached is about 99%. While for two acid mixtures at predetermined pH, the degree of dephosphorization was 97%. Finally in the process employing dilution ratio the maximum quantity of phosphorous in leached liquor is 15.5ppm at dilution ratio of 1:2, dwell time of 120 minutes and 0.40mm particle size range. The ANOVA analysis and regression information reveal both the significant effect and relevant equations. Consequently, the research objective was accomplished within the conditions of the experiment. 

TO VIEW THE FULL CONTENT OF THIS DOCUMENT, PLEASE VISIT THE UNIZIK LIBRARY WEBSITE USING THIS LINK, http://naulibrary.org/dglibrary/admin/book_directory/Thesis/11054.pdf

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