Showing papers on "Tailings published in 1979"

Oil sands hot water extraction process

Abstract: In a hot water extraction process for removing bitumen from oil sands, the efficiency is improved by filtering the wet tailings to recover hot water, bitumen and diluent which are returned and recovered in the process. Dry tailings are also produced which can be disposed of in a manner which permits reconservation of the mined out area and which eliminates environmental pollution impact on surrounding water bodies and land bodies.

Selective flotation of cubanite and chalcopyrite from copper/nickel mineralized rock

Abstract: A process for beneficiating a finely ground ore containing sulfide minerals of copper and nickel by selective flotation to produce a copper concentrate and a copper-nickel concentrate comprises pulping the ore with water to form a slurry, conditioning the slurry with an aqueous solution of SO 2 (H 2 SO 3 ) equivalent to from about 2 to about 4.5 pounds of SO 2 per ton of dry ore for a time sufficiently long to maximize depression of the nickel minerals while maximizing activation of the copper minerals, wherein the conditioned slurry contains about 30 wt. % to about 35 wt. % solids, adding a collector and a frother to the conditioned slurry, subjecting the conditioned material to a rougher flotation stage to produce a rougher copper concentrate and a rougher tailings, conditioning the rougher tailings with additional collector and with Ca(OH) 2 to activate unfloated nickel and copper minerals and subjecting the conditioned rougher tailings to froth flotation to produce a rougher copper-nickel concentrate. After regrinding, the rougher copper concentrate is conditioned with H 2 SO 3 , and subjected to one or more cleaner flotation stages to recover a final concentrate containing at least about 80% of the copper and less than about 5% of the nickel in the feed material.

Beneficiation of heavy minerals from bituminous sands residues by dry screening

Abstract: The titanium and zirconium-based minerals, present in the first stage centrifuge tailings from the hot water process for extraction of bitumen from bituminous sands, may be concentrated by a dry screening process. The tailings are burned off to provide a dry, essentially carbon-free, mineral mixture. By screening the mixture into three streams of different particle size range, silica and clays may be rejected as coarse and fine materials respectively, while titanium and zirconium minerals may be concentrated in the intermediate stream. The titanium and zirconium concentrate stream may be advanced to high tension and magnetic separation steps known in conventional processing of heavy minerals, for further beneficiation.

Method for controlling flocculant addition to tar sand tailings

Abstract: The hot water extraction process for recovering bitumen from tar sand produces a large volume of solids-laden aqueous tailings as a waste product. The solids in the tailings stream may be flocculated by the addition of time and the components of the stream then separated into a water-free solids phase and a clarified water phase. During flocculation, the zeta potential of the stream is monitored. It rises from an initial negative zeta potential, as the lime is added. Flocculation is terminated when the zeta potential is about zero. At this point, the tailings are in optimum condition for separation into the water-free solids phase and the clarified water phase. Separation is preferably effected by vacuum filtration.

Stabilized copper mill tailings for highway construction

Abstract: The results of an investigation to determine the feasibility of using stabilized copper mill tailings in road construction are presented. Properties of three types of tailings were evaluated after preliminary testing of several tailings from Arizona, Idaho, and Utah. The properties of the three tailings are summarized, and detailed results obtained for one type are reported. Index properties of the untreated tailings, including physical and mechanical properties, are given. Engineering parameters of untreated tailings are reported, including compaction characteristics; compressive, tensile, and shear strength; compressibility; permeability; and erodibility by rainfall. Properties of cement-stabilized and asphalt-stabilized tailings are also presented. The results demonstrate that copper mill tailings have excellent engineering properties and can be successfully used in road construction. In particular, the results indicate that there is excellent potential for using tailings as compacted fill in embankments, compacted foundation and subgrade material, cementlining canals, ponds, and reservoirs. (Author)

Separation of suspended solids from phosphate tailings

Abstract: A process for separating suspended clay and sand solids from the slimes of phosphate tailings is described. The suspended solids are rapidly agglomerated and a relatively dense sludge which settles to the bottom of the separation vessel is formed. The sludge may then be discharged into settling ponds for dewatering and compaction.

The microbiological control of mine waste pollution

Abstract: The removal of heavy metals and neutralisation of acidity in mine waste waters by algae and bacteria are reviewed. Algal growths in artificial meander systems have been shown to remove significant quantities of heavy metals and fine particulates from mine waste waters. Bacterial systems for the oxidation of ferrous iron and the reduction of sulphate leading to neutralisation of acidity are described. The use of bacterial extracellular polymers in the removal of heavy metals from solution is discussed with reference to its application to acid mine waters. It is concluded that a combination of bacterial and algal systems with process optimisation, including nutrient amendment, may provide suitable treatment for mine waste waters. Metal-resistant bacteria may also be important in reclamation, where it is possible that they can confer some degree of tolerance on the plants used to revegetate metal-contaminated tailings dumps.

Uranium ore processing

Abstract: Uranium ores, concentrates, calcines or tailings are processed to remove radium and thorium as well as uranium. Selected ores, concentrates or tailings, or if more appropriate, chlorination calcines thereof, are leached by selected aqueous chlorine-containing media (preferably in two stages) until uranium, radium and thorium are substantially all dissolved, with the insoluble residual solids being suitable for disposal. The leach solution is treated to recover sequentially uranium, usually thorium, and radium by selected techniques. The radium recovered can be disposed of in any environmentally-acceptable manner. The amount of iron in the residual leach liquor should be controlled to avoid iron build-up, with the barren leach solution being suitable for recycle.

Rate controlling processes in the release of radium-226 from uranium mill tailings

Abstract: Uranium mill tailings (a pyritic quartz conglomerate ore) obtained from a Canadian operation were leached according to a modification of the method recommended by I.A.E.A. for the leaching of radioactive ions from solidified wastes. A static leach test procedure was chosen to provide information to permit an assessment of hazard due to release of Ra-226 to the environment. Narrow range size fractions (53 to 75 μm) of both fresh material obtained directly from a tailings line and material weathered for approximately 10 to 15 yr in a tailings basin were leached for up to 70 days. Distilled water and an acidic synthetic effluent (pH 2.5) were chosen as leachants. Two sequential desorption processes were observed, one before and the other after a leaching period of approximately 10 to 15 days. In the later and more significant stage of desorption, the leaching behaviour could be described in terms of a diffusion mechanism. Significantly greater quantities of 226Ra were leached over relatively short leaching periods by the acidic effluent; thus the quality of the effluent and percolating water in a tailings disposal area would markedly affect the leachability of Ra from tailings. It was also found that the quantities of 226Ra leached were significantly influenced by the solid: liquid ratio at low leaching volumes.

Rate controlling processes in the release, of radium-226 from uranium mill tailings: I. Leaching study

Abstract: Uranium mill tailings (a pyritic quartz conglomerate ore) obtained from a Canadian operation were leached according to a modification of the method recommended by I.A.E.A. for the leaching of radioactive ions from solidified wastes. A static leach test procedure was chosen to provide information to permit an assessment of hazard due to release of Ra-226 to the environment. Narrow range size fractions (53 to 75 μm) of both fresh material obtained directly from a tailings line and material weathered for approximately 10 to 15 yr in a tailings basin were leached for up to 70 days. Distilled water and an acidic synthetic effluent (pH 2.5) were chosen as leachants. Two sequential desorption processes were observed, one before and the other after a leaching period of approximately 10 to 15 days. In the later and more significant stage of desorption, the leaching behaviour could be described in terms of a diffusion mechanism. Significantly greater quantities of 226Ra were leached over relatively short leaching periods by the acidic effluent; thus the quality of the effluent and percolating water in a tailings disposal area would markedly affect the leachability of Ra from tailings. It was also found that the quantities of 226Ra leached were significantly influenced by the solid: liquid ratio at low leaching volumes.

Filtering of precipitating silica

Abstract: The addition of an excess of asbestos tailings in the course of the extraction of magnesium from asbestos tailings by digestion with an acid greatly facilitates the elimination of silica and other impurities by filtration of the resulting reaction mixture. The improvement reduces the filtration time and the filtration leaves a cake which is much easier to dispose.

Emergence and growth of plant species in coal mine soil

Abstract: Experiments were conducted in the laboratory and greenhouse in Arizona with the following objectives: to evaluate the chemical properties of undisturbed soil, surface-mined coal land (coal mine soil) on the Black Mesa Coal Mine, and Gila loam soil; and to study the emergence of seven plant species in the greenhouse in Gila loam soil and coal mine soil. The pH of coal mine soil (6.2) was lower than the pH of undisturbed soil (7.5) or Gila loam (7.6). The total soluble salts in coal mine soil (3241) and undisturbed soil (4592) were much higher than in Gila loam (378); however, coal mine soil was lower in total soluble salts than undisturbed soil. The nitrogen content of coal mine soil was higher than the nitrogen content of undisturbed soil or gila loam. Emergence percentages for seven plant species grown in coal mine soil were similar to emergence percentages for the same species grown in Gila loam. Alfalfa (Medicago sativa L.), barley (Hordeum vulgare L.), and wheat (Triticum aestivum L. em Thell.) had from 84 to 93% emergence in coal mine soil. Indian ricegrass (Oryzopsis hymenoides Roem. and Shult), fourwing saltbush (Atriplex canescens Pursh), yellow sweetclover (Melilotus officinalis Lam.), and winterfat (Eurotimore » lanata Pursh.) emerged <35% in coal mine soil and Gila loam. Plant growth data from forage species grown in the greenhouse indicate that coal mine soil has a lower fertility level than does Gila loam soil. When supplied with optimum soil moisture and plant nutrients, coal mine soil produced approximately the same yields of forage from alfalfa, barley, and wheat as were produced in Gila loam under the same soil-moisture and fertility conditions.« less

Vegetational stabilization of uranium spoil areas, grants, New Mexico

Abstract: Factors that could be detrimental to vegetative stabilization of uranium mine and mill waste material were examined. Physical and chemical analyses of materials from an open-pit uranium mine and material from three inactive mill tailing piles in New Mexico were performed. Analyses for selected trace elements in mill tailing material and associated vegetation from piles in New Mexico, Colorado, and Utah were also performed. Field and laboratory experiments identified problems associated with establishing vegetation on spoil material. Problems of uptake and concentration of toxic elements by plants growing on specific spoil material were also identified. Ecological observations in conjunction with physical and chemical analyses of specific geologic units, which form the overburden and waste dumps at the open-pit mine, identified a specific geologic material that, if segregated and placed on the surface of the dumps, would pose the least set of problems for a revegetation program. A pilot revegetation project verified that segregation and use of specific geologic material in the overburden could be utilized successfully and economically for reestablishment of native vegetation on mine waste material.

Dry reaction process of asbestos tailings and ammonium sulfate

Abstract: There is disclosed a dry process for preparing magnesium sulfate by heating one surface of a reaction mixture of asbestos tailings to a temperature of from 350° to 400° C. whereby there is provided a gradient temperature between the heated zone, an intermediate zone and the outside zone where the ammonium bisulfate formed can condense in one of the last two zones which are at a temperature lower than 250° C. and react with ammonia to provide a new supply of ammonium sulfate for further reaction with the asbestos tailings and recovering the magnesium sulfate thus obtained.

Uptake of trace elements and radionuclides from uranium mill tailings by four-wing saltbush (Atriplex canescens) and alkali sacaton (Sporobolus airoides). [Radium 226; Uranium; Molybdenum; Selenium; Vanadium; Astatine]

Abstract: A greenhouse experiment was performed to determine the uptake of trace elements and radionuclides from uranium mill tailings by native plant species. Four-wing saltbush and alkali sacaton were grown in alkaline tailings covered with soil and in soil alone as controls. The tailings material was highly enriched in Ra-226, Mo, U, Se, V, and As compared with three local soils. The shrub grown in tailings had elevated concentrations of Mo, Se, Ra-226, U, As, and Na compared with the controls. Alkali sacaton contained high concentrations of Mo, Se, Ra-226, and Ni when grown on tailings. Molybdenum and selenium concentrations in plants grown in tailings are above levels reported to be toxic to grazing animals. These results indicate that the bioavailability of Mo and Se in alkaline environments makes these elements among the most hazardous contaminants present in uranium mill wastes.

Weathering studies of Bougainville mine tailings in lysimeters

Abstract: Lysimeter studies indicated that under wet tropical conditions, there was significant sulfur depletion in the upper strata of low sulfide tailing deposits within three years of exposure. The rate of acidification was influenced by drainage and aeration, and pH fell logarithmically with time. Copper mobilized by acidification was redeposited within the profile where the pH remained in excess of 7.

Visit to Japan to observe damage which occurred during the near Izu Oshima earthquakes, January 14 and 15, 1978

Abstract: : The magnitude 7.0 earthquake near Izu Oshima occurred at 12:24 p.m. on 14 January 1978. The main aftershock occurred on 15 January and had a magnitude of 5.7. These two earthquakes are believed to have caused liquefaction of tailings and two dam failures which resulted in some 80,000 cu m of tailings flowing down the mountainside and into a stream. These tailings, containing sodium cyanide, contaminated the stream all the way to the Pacific Ocean, a distance of 30 km. The tailings dams were approximately 30 m high and were constructed using the upstream construction method. These dams had been previously analyzed pseudostatically using a seimsmic coefficient of 0.2. This case history clearly indicates that a pseudostatic analysis using routine static soil properties as input is not appropriate if liquefaction is the mode of failure. (Author)

Purification of flotation tailings water

Abstract: Tailings slurry from fluorspar flotation is clarified and purified by sequential addition of a cationic polygalactomannan derivative and a poly(ethylene oxide).