Showing papers on "Tailings published in 1988"

Chemistry and biology of solid waste: Dredged material and mine tailings

Abstract: Mine tailings and dredged materials are solid wastes, which are produced at single sites in huge quantities. Mine tailings, compared to the more recent environmental implications with dredged materials, have been recognized as problematic materials for a long time. A major part of mineral reserves are in less-developed countries, and a disproportionate fraction of resource development is expected to take place in areas where environmental protection measures may be limited. As a result of this situation: (1) reclamation should be carried out during the life of the mine; (2) technology to ameliorate long-term effects should be as self-supporting as possible; (3) simple, reliable, low-energy techniques for minimizing deleterious effects of mining should be developed. Separate abstracts are processed for 11 chapters in this book for inclusion in the appropriate data base.

Environmental management of solid waste. Dredged material and mine tailings.

Abstract: The problems and questions mine tailings and dredged materials pose with regard to safe environmental deposition are similar: aquatic versus terrestrial disposal, revegetation, leaching of contaminants. Larger projects in the fields of both mine tailings reclamation and dredged material disposal are increasingly requiring a multidisciplinary team approach. A major part of mineral reserves are in less-developed countries with limited environmental controls. Such experience implies far-going demands from the host countries: (1) reclamation should be carried out, as far as possible, during the life of the mine; (2) technology to ameliorate long-term effects should be as self-supporting as possible; (3) simple, reliable, low-energy techniques for minimizing deleterious effects of mining should be developed. Separate abstracts are processed for 14 chapters in this book for inclusion in the appropriate data bases.

Variability of the Metal Content of Flood Deposits

Abstract: Fresh flood deposits were sampled in the floodplains of two river systems, the River Meuse, with a catchment area of 33,000 km2 and the River Geul, with a catchment area of 3000 km2 As a result of industrial and mining activities, both rivers have a history of severe metal pollution, especially with zinc, lead, and cadmium The flood deposits of both rivers are heterogeneous mixtures of contaminated bottom sediments (with relatively long residence times in the river) and clean sediments derived from soil erosion on agricultural cropland (with very short residence times) An additional source of sediment is formed by erosion of older, locally highly contaminated streambank deposits These older sediments are polluted as a result of solid waste disposal containing metalliferous ore and tailings in the sand fraction This is especially the case in the River Geul which drains an old zinc and lead mining area The metal content of the Meuse sediments, however, originates largely from liquid industrial wastes and occurs mainly in the clay fraction For this reason, the positive correlation between textural composition, organic matter content, and heavy metal concentration, which is often reported, was not observed, and normalization of the metal content was not possible Nevertheless, a clear decrease of contamination was noticed along the River Geul; this trend was absent along the River Meuse An attempt has been made to model the longitudinal decay pattern for each of the investigated heavy metals

Microbiological Oxidations of Minerals in Mine Tailings

Abstract: Industrially significant metal sulfides are relatively stable in their natural crystalline form. As a result of mining activities, these minerals are exposed and interact with water, oxygen, carbon dioxide, and soluble chemical species, factors which collectively enhance the mineral dissolution. The very nature of mining practices such as milling and grinding, which are designed to maximize metal recovery, also ensure maximum surface area exposure of mine tailings and waste materials to subsequent oxidative processes.

Comparative uptake of U and Th by native plants at a U production site.

Abstract: During a 3- to 4-year period, concentrations of 238U, 234U, 230Th, 232Th and 228Th were determined in soils and native vegetation at various sites around a typical U mining and milling operation in Wyoming. Plant/soil concentration ratios (CR) for U and Th isotopes were estimated for (1) exposed, weathered tailings, (2) the edge of a tailings impoundment, (3) an area downwind from exposed tailings, (4) a reclamation area and (5) several background, native range locations. The 238U/234U concentration ratio of 0.9 to 1.1 in soil and vegetation indicated near-radioactive equilibrium of both radionuclides at all locations. Mean concentrations of the U and Th isotopes in background soil ranged from 44 to 52 mBq g-1. Concentrations of 238U and 230Th in soil and vegetation were elevated above background at all sites disturbed by mining and milling activities. Uranium concentrations in tailings and invading vegetation were an order of magnitude greater than in the background locations, whereas 230Th concentrations were elevated above background by some two orders of magnitude. No demonstrable differences in radionuclide concentrations between plant groups and collection years were found. The observed CR values for 238U and 230Th of 0.81 and 0.69 for vegetation growing on exposed tailings weremore » elevated above native range by factors of 9.0 and 3.6, respectively, and generally higher than other published values. Exceptionally high CR values for 230Th (1.9-2.9) observed near the tailings impoundment demonstrate that under certain conditions, vegetation can accumulate 230Th to a much greater extent than previously reported. Vegetation concentrations were lower for 232Th relative to 230Th and 228Th at locations where they are present at similar soil concentrations.« less

Aquatic insects as environmental monitors of trace metal contamination: Red River, New Mexico

Abstract: Discontinuous sampling of water for toxic chemicals is unreliable in lotic ecosystems or in systems subjected to sporadic discharges. Such sampling either fails to detect the contaminants or seriously underestimates their concentrations. This study explored the use of resident aquatic insects as biomonitors of trace metal contamination in a river subjected to episodic spills of Mo mill tailings. Aquatic insects at sites downstream from the mill accumulated more Mo and Cu than upstream insects. Due to a prolonged shutdown at the mine, no tailings spills were recorded during this study and Mo and Cu levels in water and bottom sediments declined to near background levels. However, concentrations of these metals in insects declined only slightly. This study indicates that aquatic insects are useful biomonitors of trace metal contamination in an intermittently impacted system. Reduction of elevated trace metal concentrations from the insects occurred at a slower rate than from the non-living components of the river ecosystem thereby facilitating detection of the spills.

The effect of uranium mine tailings on radionuclide concentrations in Langley Bay, Saskatchewan, Canada.

Abstract: From 1955 to 1964 the Gunnar Uranium Mine (Canada) produced approximately 8×103 tonnes of uranium oxide and about 5×106 tonnes of waste rock tailings. Large quantities of fine tailings material washed into Langley Bay, a shallow bay opening onto Lake Athabasca. The limnoiogical characteristics of this bay make it an ideal site to study the movement and impact of some radionuclides in and on the northern environment. This paper describes the physical, chemical, and biological characteristics of Langley Bay and introduces a study of radionuclide movement begun in 1983.

Response of Plants and Vegetation to Mine Tailings and Dredged Materials

Abstract: Mine tailings and disposal sites of dredged materials are new environments which have been superimposed on existing ones; at the same time open mining casts and the dredging sites themselves are disturbing existing ecosystems. Tailings from mineral operations and dredged materials can be stored as upland or underwater disposals including the backfilling of mined-out areas (Andrews 1975). The bare surfaces of above ground disposals are open to erosion by water and wind without a protective vegetation. Therefore, the final aim of managing these sites is primarily to diminish the environmental impact on the surrounding landscape by stabilizing these dumps by vegetation, because technical solutions have proved to be insufficient (Greszta 1973; Barner 1978). The possibilities far revegetation of surface and underwater disposal sites depend on the ability of the colonizing plant species to respond adequately with their roots and shoots to the physical structure and the chemical composition of these materials. With regard to the high diversity of structures and compounds the statement is appropriate: “No combination of environmental factors in mine tailings and dredged materials seems to be impossible’ (Ernst and Joosse-van Damme 1983). The biological answer to combinations of extreme environmental factors is more restricted: “Not all is possible for plant growth”. This contribution will present some general principals which have to operate in plant populations and vegetation if revegetation is to be a successful enterprise either on upland or underwater sites. No special attention will be given to the impact of disposal sites on the surroundings, because pollution by wind and water erosion causes similar stress on the affected ecosystems as on the vegetation of the disposal site itself.

Diagenetic Processes in Aquatic Mine Tailings Deposits in British Columbia

Abstract: Mine wastes have been deposited in coastal or terrestrial aquatic systems for at least two millenia, historically without regard for the biological, chemical or physical consequences of such disposal. The rise of industrialization and coincident exponential growth in the rates of metal consumption and exploitation have been associated with a profound increase in the annual volume of mine tailings requiring permanent storage on the earth’s surface. A parallel consequence has been the steady shift towards exploitation of lower grade, larger volume orebodies which has radically increased the volume of tailings produced by most contemporary milling operations. This phenomenon has increased the need to find or construct large-volume repositories for tailings storage near mine sites; when coupled with the growing awareness of the serious long-term environmental risks posed by terrestrial disposal, and typical attractive economics, submerged storage in both fresh and saline waters is becoming an increasingly appealing alternative.

Biological Engineering of Marine Tailings Beds

Abstract: At coastal and marine mines, tailings are discharged to the sea, often in enormous amounts, and they form beds similar in many ways to the deposits naturally settling there (see Chap. 6). We should expect these tailings beds to be colonised by marine organisms natural to the area in ways comparable to the biological colonisation of mine waste on land. However, compared to the enormous literature about reclamation processes on land, there is virtually no published information on the reclamation of submerged and shoreline mine tailings. This chapter collates what little information is available, largely from limited distribution reports. We also raise issues about reclaiming marine-discharged tailings beds to biologically productive ecosystems. This is what we mean by the term “biological engineering” in our context.

A study of radionuclides in vegetation on abandoned uranium tailings

Abstract: A study has been carried out of the uptake of uranium and other radionuclides by plants growing on abandoned tailings from an uranium mining operation. Assay methods included instrumental neutron activation analysis, delayed neutron counting, fission track imaging, and counting of natural radioactivity. Care was taken to avoid contamination of the plant material and a number of methods are described to identify such contamination. All plants observed showed high uptake of radionuclides, compared to plants studied from naturally uraniferous and control areas. Graminoid (grass-like) plants showed significant uptake in the above-ground parts while woody plants showed exceedingly high uranium accumulation in the root portions. These results have significance in determination of the spread of radioactive material from such sites.

Ecological Engineering: Biological and Geochemical Aspects Phase I Experiments

Abstract: Perpetual operation of acid mine drainage treatment facilities after mine closure imposes economic burdens and environmental liabilities which are difficult to overcome The main goal of ecological engineering research is the development of methods which facilitate the establishment of vegetation cover types to serve as self-maintaining acid drainage treatment systems Summarized below are the objectives and results of experiments on tailings and in the laboratory for five aspects relevant to the development of close-out scenarios for acid-generating tailings sites in temperate climates 1 On dry surface areas with sparse vegetation covers, terrestrial moss covers curtail infiltration of precipitation Vascular plant covers investigated had no amelioration effect on the underlaying tailings Introduction and promotion of terrestrial mosses require further research 2 Wetlands established in waterlogged, submerged sections and seepages reduce water infiltration and acid generation, as well as removing metals Hand-transplanted cattails showed a 200% increase in number after 1 year Hydroponic methods tested to date indicated little promise Seed germination of some wetland plants was reported on neutralized pyrrhotite Iron removal in seepages was found to be catalyzed by the surface provided by organic matter Two species of aquatic mosses can serve as biological polishing agents where flow rates are low 3 The precipitates in settling and polishing ponds from treatment plant operation have to be maintained in an alkaline state Some species of Charophytes, attached macroscopic algae, have been tested extensively for these conditions and appear to be suitable 4 Relative abundance values for 18O in sulfate produced at one tailings site indicate that a major proportion of the sulfate oxygen is derived from water molecules rather than from molecular oxygen, suggesting that the oxidation process proceeds partly under anaerobic, water-saturated conditions The water is slowly moving through the tailings It is likely that the oxidation of sulfides in the tailings can be stopped only if the tailings are permanently submerged in completely stagnant water 5 Data from freezing gauges and a thermistor cable installed in the tailings indicate that frost penetration in the tailings is minimal, suggesting that the rate of sulfide oxidation may not be reduced significantly during the winter

Mine Tailings Reclamation. Inco Limited’s Experience with the Reclaiming of Sulphide Tailings in the Sudbury Area, Ontario, Canada

Abstract: In 1975, an inventory of mine wastes throughout Canada was undertaken by the Canada Department of Mines, Energy and Resources. In all, 718 mine sites were assessed as to the area, type and vegetation cover associated with the waste material. It estimated that there were approximately 45,300 ha of land affected by waste rock, overburden or tailings (Murray, 1985). It is of interest to note that 7,300 ha or about 16% of this land had been revegetated to some extent.

Cyanide regeneration process

Abstract: A process for removing and recovering cyanide from a cyanide-containing solution. The process includes the steps of adjusting the pH of the cyanide-containing solution to between about pH 6 and about pH 9.5, volatilizing the HCN contained in the pH adjusted solution and contacting the volatilized HCN with basic material. Preferably, the cyanide recovery process is performed on tailings slurries resulting from metal recovery processes.

Plant/soil concentration ratios of 226Ra for contrasting sites around an active U mine-mill.

Abstract: Concentrations of 226Ra were determined in native vegetation and underlying substrate (soil and tailings) at various sites around a conventional open-pit, acid leach U production operation in Wyoming. Plant/soil concentration ratios (CRs) for 226Ra were estimated for various sites, including weathered tailings; a tailings impoundment shoreline; downwind from exposed tailings; a mine overburden reclamation area; and several background locations. Radium-226 concentrations for vegetation and substrate and CR values from the perturbed sites were elevated above background. The highest vegetation concentration (1.3 Bq g-1) was found in a grass which had invaded exposed, weathered tailings. Levels of 226Ra in soil and vegetation and CR values decreased with distance from the tailings impoundment edge. CR values varied significantly among sites, but few differences were found between plant species groups. The observed CR values ranged from 0.07 at the background and reclamation areas to 0.4 downwind from the tailings area. Average CR values for plants growing on exposed tailings and within one meter from the impoundment edge were 0.15 and 0.3, respectively. CR values of 226Ra for plants on tailings substrates were comparatively low in contrast to other radionuclides in the U chain. We speculate that in the case of sulfuric acid leachedmore » tailings-derived material, 226Ra is sequestered as sulfate, which is highly insoluble relative to the sulfates of the other elements (e.g., U and Th) resulting in reduced availability for plant uptake.« less

Integrated Biological Systems for Effluent Treatment from Mine and Mill Tailings

Abstract: Biological processes are of course routinely used in the treatment of municipal waste water. Randol (1985) has just completed a comprehensive encyclopedia on Waste Management in Mining and Metallurgical Operations and one of the interesting discoveries is that if treated municipal waste water is used for mineral processing, e.g., flotation, then the type of biological process applied in the municipal treatment plant is all important. Waste treated by conventional biofilters is more often than not unsuitable for use in the flotation process. However, these are more sophisticated multistage activated sludge processes that seem to render this type of water suitable for this purpose without reducing recoveries. The important point is that biological processes can be developed for routine use in the treatment of waste and effluents.

The distribution of Agrostis gigantea and Poa pratensis in relation to some environmental factors on a mine-tailings area at Copper Cliff, Ontario

Abstract: The distribution of two dominant species of grass was related to selected soil characteristics on revegetated Cu–Ni tailings at Copper Cliff, Ont. The tailings area had a wet zone dominated by Agrostis gigantea, a dry zone dominated by Poa pratensis, and an overlapping zone of both grasses. In the overlapping zone the biomass–cover index of both species was lower than in their specific zones. pH ranged from 3.3 to 6.7, and sites of Poa pratensis were generally above pH 5. Tailings Fe, extractable by ammonium acetate, ranged from 5 to 344, Cu from 5 to 15, and Ni from 5 to 80 μg∙g−1. There were significant differences in Fe, Cu, and Ni between the Agrostis and Poa zones, and between Poa pratensis sites in the Poa and overlapping zones. Concentrations of metal in roots of Agrostis gigantea were 2.7 × 103–46.4 × 103, 216–1289, and 108–826 μg∙g−1 for Fe, Cu, and Ni, respectively; in Poa pratensis root concentrations of metal were 2.2 × 103–20.3 × 103, 100–1589, and 99–795 μg∙g−1 for Fe, Cu, and Ni, respective...

Effects of phosphorus application and mycorrhizal inoculation on white clover (Trifolium repens) growth in andesite tailings from Martha Mine, Waihi

Abstract: The effects of mycorrhizal inoculation and level of applied phosphorus (P) on the growth of white clover (Trifolium repens) in tailings material from a gold and silver extraction process which involved cyanide leaching were examined. White clover gave large growth responses to increasing levels of applied P (0 - 180 μg P/g tailings) and very little growth occurred at low levels of applied P (below 45 μg P/g tailings). At medium - high levels of applied P, inoculation with the vesicular arbuscular mycorrhizal fungus Glomus mosseae resulted in significantly increased yields. Inoculation with topsoil from a site adjacent to the proposed tailings disposal area did not increase plant yields in comparison with plants inoculated with sterilised topsoil. However, there were increased yields in response to both topsoil treatments early on in the experiment. The tailings material appeared to have little or no adverse effect on the development of nitrogen-fixing capacity or mycorrhizal roots. The growth of ...

Limestone Crusher-Run and Tailings in Compaction Concrete for Pavement Applications

Abstract: Laboratory experimentation indicates that both limestone crusher-run and finely grained limestone tailings (by-products of the aggregate-mining industry) can be used in concrete made with an emerging technology for flatwork contruction known as roller compacted concrete (RCC) This paper reports on tests of laboratory specimens using various combinations of mix components and proportions The unit cost of concrete progressively decreases as the graded coarse aggregate is substituted with the crusher-run and as the tailings are added On the other hand, the compressive strength of mixtures including the crusher-run is better than that of graded coarse aggregate and is further improved by the addition of tailings

Process for recovery of bitumen from waste water of tar sands processing

Abstract: A process for the recovery of diluent and bitumen from the aqueous phase separated from an electrostatic treater used to separate bitumen from tar sands tailings to which a diluent such as naphtha has been added by adding a clay deflocculant to such diluted tailings and allowing separation to a top organic layer and a bottom aqueous layer essentially free of organic material, and separating the layers to recover the organic diluent and the bitumen.