Particulates in hydrometallurgy: Part II. Dewatering behavior of unflocculated laterite acid leach residues
- PDF / 542,818 Bytes
- 6 Pages / 597.28 x 785 pts Page_size
- 2 Downloads / 156 Views
I.
II.
INTRODUCTION
CERTAIN low-grade ores are found in nature in a finely divided state (e.g., laterite ores and ocean-floor manganese nodules). Other low-grade ores require fine grinding in order to enhance the exposure of the metal values to the lixiviant. Thus, the growing need to process low-grade ores has considerably increased the slime disposal problem. According to Davies and Goldberg, vJ the solid-liquid separation steps are likely to represent 10 to 25 pct of the capital cost of a hydrometaUurgical manganese nodules processing plant. Slimes generated in hydrometallurgical processing plants are treated through operations of solid-liquid separation in which the solid fraction is separated from the liquid at one or more stages. The aim of these operations is to recover the solid for retreatment or disposal and to separate the liquid for metal recovery, recycling, or disposal. This article is concerned with the dewatering behavior of unflocculated laterite leach residues; the effects of polymeric flocculants are considered in a subsequent article, t2a The emphasis here is on the effects of leaching conditions (e.g., temperature, pH, and solid/liquid ratio) on the solidliquid separation process. The performance of the residues was evaluated by using as parameters the settling rate and filtration time, as well as the supernatant turbidity of the suspensions. In the previous article, [3~ the leach residues were characterized by a variety of techniques.
A. BRICENO, formerly Graduate Student, Department of Materials Science and Engineering, The Pennsylvania State University, is with the Department of Mining, University of Ofiente, Venezuela. K. OSSEOASARE, Professor and Program Chair, is with the Metals Science and Engineering Program, Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802. Manuscript submitted April 1, 1993. METALLURGICAL AND MATERIALSTRANSACTIONS B
EXPERIMENTAL
A. Materials The preparation (including leaching) and characterization of the solids (raw ore and leach residues) used in the phase separation experiments were described in the previous article, r3j Two different laterite ores, designated as Ore Nos. 1 and 2, respectively, were used. Ore No. 1 contained 74.8 pct Fe203 and was therefore limonitic (i.e., the ore matrix consisted primarily of iron oxide minerals). On the other hand, Ore No. 2, with 49.6 pct Fe203 and 21.3 pct SiO2, represented a transitional laterite ore, i.e., it consisted of a mixture of limonitic and garnieritic (silicate-rich) materialJ 3~ The surface areas of raw Ore Nos. 1 and 2 were found to be 4.8 and 2.6 mVg, respectively.t3]
B. Standard Mixing Tank Mixing and conditioning procedures are of primary importance in any process involving heterogeneous systems. For instance, in a suspension in which solids react with the liquid phase, reactants must be brought close enough to one another to keep the reaction going. The manner in which the reactants are mixed and conditioned will dictate the rate of reaction a
Data Loading...
