Leaching of chrysocolla with Ammonia-Ammonium carbonate solutions
- PDF / 1,111,133 Bytes
- 8 Pages / 614.28 x 794.28 pts Page_size
- 4 Downloads / 210 Views
I.
II.
INTRODUCTION
C H R Y S O C O L L A , a hydrous copper silicate, CuO. SiO2" 2H:O, found in the upper oxidation zones of copper deposits, is commonly associated with malachite, azurite, and limonite. ~ Samples vary widely in composition, but using the above formula chrysocolla has a copper content of 36.18 pct as compared to 34.62 pct for chalcopyrite, Large ore deposits of chrysocolla are found throughout the world, some of which are presently being mined.: Unfortunately, chrysocolla is not easily concentrated for froth flotation like chalcopyrite. The direct smelting of high grade oxide ores has been reported, 3 but such an alternative would not be applicable to a majority of oxide ore deposits which are low grade, Hydrometallurgy, however, opens the possibilities of exploiting such deposits. Chrysocolla has been leached with various agents like EDTA 5 and NTA, 6 cyanide solutions, 7'* and ammoniacal solutions.8,9,10 Although the sulfuric acid leaching of chrysocolla has been generally accepted as practical, the preponderance of carbonates in certain ore deposits can cause tremendous increases in acid consumption, thus creating the need for a more selective reagent for such deposits. Ammonia is an attractive reagent because it does not react with carbonates, and because of its ease of handling, low inventory cost, and amenability to regeneration. The NH3-COeH,O system was therefore chosen in the investigation of the kinetics of copper dissolution from chrysocolla. The variables studied were ammonia-ammonium ratio, total ammonia concentration, temperature, and initial particle size. The roles of these variables in terms of leaching rate are interpreted using the residue analyses: SEM and EDAX. Surface area and infrared measurements as well as X-ray studies were also conducted.
M. MENA, formerly Graduate Student, Department of Metallurgy and Metallurgical Engineering, Umverslty of Utah, is now Assistant Professor of Extractive Metallurgy, Department of Mining and Metallurgmal Engineering, UmversW of the Philippines, Dlhman, Quezon City 3004, Philippine Islands. F A OLSON is a Professor of Metallurgy, Department of Metallurgy and Metallurgical Engineering, University of Utah, Salt Lake C W, UT 84112. Manuscript submitted March 28, 1984 METALLURGICALTRANSACTIONS B
EXPERIMENTAL
A. Materials The chrysocolla samples were from an upgraded ore from Globe, Arizona. The mineral was ground using a Fisher Mortar Grinder into five size fractions between 100 mesh and 400 mesh. Each size fraction was analyzed for copper using an atomic absorption spectrophotometer, and the copper content of the samples varied from 33.01 pct to 36.16 pct, with a slight tendency for the chrysocolla to concentrate in the finer size fractions. The composition and purity of the samples were determined using combined gravimetric and atomic absorption techniques. The chemical formula CuO S i 0 2 " 8 9 was obtained and based on this formula, the samples contained 91 pct chrysocolla, with the remaining 9 pct being free silica. Both X-ray and i
Data Loading...
