Acid-leach tailings

Results of batch leach tests performed on tailings from the Grants Mineral Belt, New Mexico are summarized in Tables IV and V. These results represent the average of two analyses on the acid leach tailings samples. Table IV contains the elemental concentrations of the sand and silt and clay-sized fractions, as well as the soluble concentration of each element found when 100 g of material is leached with 250 mL of sodium hexametaphosphate solution. The right-most column presents the ratio of the elemental concentration associated with the silt and clay-sized fraction to that of the sand-sized fraction, and it is presented as an enrichment factor. The high enrichment factors for As, Mo, Cr, Se, and V may be due to the fact that these elements are adsorbed onto jarosite, montmorillonite, and ferric oxyhydroxides (9-141. Speciation... 

Table IX. Saturation Indices (SI = log (lAP/Kj,)) for Acid Leach Tailings Raffinate, Maybell, Colorado. Computed by PHREEQE (20)...

Fig. 1. Schematic flowsheet of uranium processing (acid leach and ion exchange) operation. Numbers refer to the numbers that appear in the boxes on the flowsheet. Operations (3), (6), (9), and (11) may be done by thickening or filtration. Most often, thickeners are used, followed by filters. The pH of the leach slurry <4) is elevated to reduce its corrosive effect and to improve the ion-exchange operation on the uranium liquor subsequently separated, In tile ion exchange operation (7), resin contained in closed columns is alternately loaded with uranium and then eluted. The resin adsorbs the complex anions, such as UC fSO 4-. in which the uranium is present in the leach solution. Ammonium nitrate is nsed for elution, obtained by recycling the uranium filtrate liquor after pH adjustment. Iron adsoibed with the uranium is eluted with it. Iron separation operation (8) is needed inasmuch as the iron hydroxide slurry is heavily contaminated with calcium sulfate and coprecipitated uranium salts. Therefore, the slurry is recycled to the watering stage (3). Washed solids from 1,6). the waste barren liquor from (7), and the uranium filtrate from (11) are combined. The pH is elevated to 7.5 by adding lime slurry before the mixture is pumped to the tailings disposal area. (Rio Algom Mines Limited, Toronto)...

Note Values are in mg/kg except as indicated. All samples except the Bluewater Mill sample acquired their initial acidities and solutes because of pyrite oxidation. The Bluewater Mill tailings solution is derived from sulfuric acid leaching of uraniferous sandstone ore. Although listed as Fe(III), iron concentrations in the Bluewater Mill solution and Coal A leachate are total iron values. Except for Bluewater Mill and Coal A laboratory studies. Eh and pH values were measured in the field. All samples were filtered through 0A5foa filters prior to acidification, except for Well 201. 

Li M. G Jacob, C., and Comeau, G., 1996. Decommissioning of sulphuric acid-leached by rinsing, in Proceedings of Tailings and Mine Waste 96, Rotterdam, Balkema, pp. 295-304. 

Table I. Concentrations of Selected Constituents of Acid-Leach Uranium Mill Tailings Pond Raffmates, Grants Mineral Belt,...

Concentrations in 250 mL of solution containing 100 g of acid leach uranium tailings. ... 

Table V. Distribution of the Total Mass of Each Element from a 100 g Sample of Acid Leach Uranium Tailings, Grants Mineral Belt, New Mexico ...

Caron Plant Tailing Leach Results. An example of the type of data obtained from leaching of Caron plant tailings is summarized in Table 2 below. The nickel and cobalt leaching results of the 8 acid leach experiments are summarized in Table 3 below. 

Table III. Starved Acid Leach Experiments Treating Caron Plant Tailings. 

A total of eight leaching experiments were carried out on a Caron plant tailings sample containing 0.51% Ni and 0.054% Co. The extraction of nickel and cobalt were affected by acid addition and temperature (with oxidation). The most attractive economics were obtained with low acid addition (as per the starved acid leach technology concept). 

Dreisinger, D., Clucas, J., 2012. The Starved Acid Leach Technology (SALT) for Processing of Nickel Laterites and Caron Plant Tailings , Proc. of WALSIM II, Eds. C.Q. Jia, M. Sudbury, J. Zinck, V. Ramachandran, E.A. Morris, CM METSOC, Montreal, 39-51. 

Because the leaching also dissolves the iron, a removal step is needed. Moreover, silver and lead remain in the residue and are either recovered or disposed of depending on the economy of the process. Recovery of silver and lead is performed by smelting, in lead smelters, either the entire acid leach residue or the silver-rich lead concentrate produced by a flotation on the residue. In the case of flotation, the tailing is mixed with the iron residue. For precipitating iron from the leaching Hquor, three different processes are available ... 

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