Thickened tailings

Backfill paste is formed by dewatering slurry of tailings (thickening and filtering). Mixing dewatered slurry with cement (3%-5%) produces a stiff backfill (1.5-3.5 MPa strength, or 218 508 psi). Coarse aggregates (<20 mm, or in) must be present. Concrete pumps can be used. 

Copper concentration Copper ore, water, chemical reagents, thickeners Flotation wastewaters Tailings containing waste minerals such as limestone, and quartz... 

The niobium circuit flowsheet (Figure 22.7) was modified to include (a) thickening of the deslimed calcite tailing before flotation, and (b) retreatment of the niobium cleaner tailing for extra niobium recovery. 

The bulk flotation can be accomplished with the addition of small doses of oleic acid plus oxidized emulsion of fuel oil. The fuel oil is treated with 10% solution of NaOH at a temperature of 60-80°C for 1 h. The following method was used for rutile-zircon separation the concentrate was thickened, followed by heat conditioning to 60°C. After the heat treatment, the zircon was floated without the addition of collector. The zirconium tailing is the rutile concentrate. The zircon concentrate was thickened, followed by gravity cleaning. In some cases, the heat-treated pulp is washed before zircon flotation. The following metallurgical results were obtained ... 

Fig. 3. The beneficiation of taconite ore on Ihe iron range requires large volumes of water in concenlrating by magnetic separation. To eliminate massive waste-disposal problems, huge thickeners, such as the 300-foot (91,5-meter) diameter caisson unit shown here, are used. This system will handle over 70 million gallons (265 million liters) per day or 50,000 gallons (189,250 liters) per minute of liquid and 250 tons per day of suspended solids. Clarifying the waste tailing stream permits reclamation of water on a large scale for plant reuse...

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)...

To avoid the occurrence of tailings ponds, and their associated problems, some mineral-process tailings are drawn off from the rougher and scavenger stages, thickened, de-watered in centrifuges, and then dried in, for example, gravity-fed, direct-fired driers for dry disposal. 

In solutions of water and surfactant, the surfactant monolayers can join, tail side against tail side, to form bilayers, which form lamellar liquid crystals whose bilayers are planar and are arrayed periodically in the direction normal to the bilayer surface. The bilayer thickens upon addition of oil, and the distance between bilayers can be changed by adding salts or other solutes. In the oil-free case, the hydrocarbon tails can be fluidlike (La) lamellar liquid crystal or can be solidlike (Lp) lamellar liquid crystal. There also occurs another phase, Pp, called the modulated or rippled phase, in which the bilayer thickness varies chaotically in place of the lamellae. Assuming lamellar liquid crystalline symmetry, Goldstein and Leibler [19] have constructed a Hamiltonian in which (1) the intrabilayer energy is calculated... 

Al T. A. (1996) The hydrology and geochemistry of thickened, sulfide-rich tailings, Kidd Creek Mine, Timmins, Ontario. PhD Thesis, University of Waterloo. 

Al T. A. and Blowes D. W. (1996) Storm-water hydrograph separation of run off from a mine-tailings impoundment formed by thickened tailings discharge at Kidd Creek, Timmins, Ontario. J. Hydrol. 180, 55-78. 

Robinsky E. (1978) Tailings disposal by the thickened discharge method for improved economy and environmental control. In Tailings Disposal Today, Proc. 2nd Int. Tailings Symp., Miller Freeman San Francisco, CA, vol. 2, pp. 75-92. 

Robinsky E., Barbour S. F., Wilson G. W., Bordin D., and Fredlund D. G. (1991) Thickened sloped tailings disposal an evaluation of seepage and abatement of acid drainage. In 2nd Int. Conf Abatement of Acidic Drainage. MEND Secretariat, vol. 1, pp. 529-550. 

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