The Leaching of Hematite in Acid Solutions
- PDF / 702,312 Bytes
- 8 Pages / 614.28 x 794.28 pts Page_size
- 43 Downloads / 271 Views
I.
INTRODUCTION
ACIDleaching reactions of metal oxide ores of Zr, U, Be, Ti, Cu, and others are widely utilized in hydrometallurgy. In a paper by Warren and Devuyst, 1 a general mechanism for the leaching of metal oxides was proposed. However, some features of the leaching mechanism still remain to be investigated. Recently Majima et al. 2 studied the dissolution reaction of cupric oxide in various acid solutions and found that the dissolution rate was first order with respect to the activity of hydrogen ions for perchloric, nitric, and hydrochloric acids, while it was a half order for sulfuric acid. They also observed that the addition of electrolytes having anions common to the acid solutions resulted in an acceleration of the dissolution rates due to increases m the activity of the hydrogen ions. The addition of electrolytes having uncommon anions produced a markedly different effect on dissolution rate. From these observations the importance of the role of anions in dissolution reactions was clearly established. At that time the role of anions in affecting the dissolution rates in acid solutions was not determined.-" Hematite is one of the interesting oxide minerals from a leaching viewpoint. Many fundamental studies have been made on the leaching of iron oxide, 13-" but some features of the leaching mechanism still remain to be elucidated. In the present study the authors examined the dependence of leaching rate on hydrogen ion activity and the role of anions in the leaching of hematite in various acids, providing some detail toward a fuller understanding of the dissolution mechanism. II.
EXPERIMENTAL
A. Materials The hematite used for these experiments was in the form of high grade lumps about 5 cm in diameter each, obtained HIROSHI MAJIMA, Professor, and YASUHIRO AWAKURA, Instructor, are with the Department of Metallurgy, Kyoto University, Kyoto, Japan 606. TAKUMI MISHIMA, formerly Graduate Student, Kyoto Umverslty. is now Research Engineer, Mitsub~shi Metal Corporanon, Osaka Refinery. Kita-ku, Osaka, Japan 530. Manuscnpt submitted May 16, 1984 METALLURGICALTRANSACTIONS B
from the Bailadila Mine, India. Chemical analysis of this material yielded an iron content of 66.8 pct, corresponding to a Fe,O3 content of 95.4 pct. X-ray diffraction showed the existence of no particular contaminating minerals. Spectrographic analysis indicated the presence of only traces of A1, Si, Cu, and Zn. The mineral was crushed and sized by wet screening to provide a clean - 1 5 0 +200 mesh (Tyler standard) fraction for these leaching studies. All chemicals used were of reagent grade. Deionized water was used in the preparation of all the solutions.
B. Experimental Procedures Particulate leaching experiments were carried out in a covered one liter Pyrex separable flask immersed in a thermostatically-controlled water bath. The temperature within the flask was maintained -+ 0.1 K of the noted values. The leaching solution containing monosized particulates of hematite was agitated with a Teflon stirrer. Solution samples were with
Data Loading...
