Search Documents

By T. J. Fronapfel

Impacts to ground water from mining are being comprehensively regulated in Nevada through specific requirements for design, construction, operation, permitting and closure. This program is the nation's most comprehensive for control of activities at mining operations which have the potential to cause groundwater degradation. It encompasses virtually all types of facilities, including placer, physical separation, flotation, testing, leaching and milling. Minimum design requirements are established by regulation, and must be met by each facility. Site-specific monitoring requirements are established for each facility, and are heavily emphasized. Regulatory and technical requirements and relevant permit conditions are presented and discussed.

Jan 1, 1992

One of the problems associated with the maintenance of roadways in underground coal mines is that of dealing with roadway closure. Sidewall weakening technique is based on the transference of the high stress zone further away from the vicinity of roadway. This transferral is carried out by weakening parts of sidewalls of roadway by cut- ting slot, drilling a series of parallel holes or blasting during development stage. In the paper, the effect of sidewall weakening on the stability of roadway is studied by finite element analysis and field experiment. The finite element analysis shows that sidewall weakening can control the development of yield zone around a roadway, improving the stability of roadway. It is also shown that if in- situ horizontal stress is lower or higher than the in-situ vertical stress, it is difficult to obtain roadway stability by sidewall weakening. The field experiment shows that roadway closure can be controlled by sidewall weakening with blasting.

Jan 1, 1990

By Beatryz C. Mendes, Henrique de Paula Santos, Kléos M. L. Cesar, Eduardo Antônio G. Marques, Maurício Paulo F. Fontes, Rita de Cássia S. S. Alvarenga

Inadequate discard of industrial solid waste is a risk to human health and to the environment. Aiming at softening environmental damage caused by deposition on soil of an ink residue, from washing of printers used in carton box packages, it is intended to incorporate this residue into soil-cement bricks. The residue has other use potentialities such as in screeds, pavement parts, fertilizer, paints, etc. However, to explore these potentialities it is fundamental to assess the risks that the several forms of use of this residue can cause. For such, in this work the chemical analysis of the residue was performed in order to know its main chemical compounds, in addition to its characteristics of leaching and solubilization. The chemical composition assay showed traces of some heavy metals such as Pb, Cd, Cr, Zn, Al and Cu, although the residue-generating company uses ink labeled as heavy metals free. Among the elements analyzed in leaching and solubilization, some had concentration above the limit allowed by The Brazilian Codes. This code is based on CFR—Title 40—Protection of Environment—Part 260–265—Harzardous waste management. Therefore, it is suggested that the residue has a limited use to avoid contamination of ground water.

Mar 1, 2017

By Ross Nairn

"Tulawaka Mine is a joint venture between Pangea Minerals Limited 70% (a wholly-owned subsidiary of Barrick Gold Corporation) and Northern Mining 30%. Tulawaka Mine is located in North West of Tanzania in the Lake Victoria Goldfields. Tulawaka Mine is scheduled to process 360,000 tonnes per year at an average 11.5 g/t head grade over a 4 year mine life.The Tulawaka Process Plant uses single stage crushing, single stage SAG milling, gravity, intensive leach of gravity concentrates, CIL, Zadra desorption and cyanide detoxification to process the ore. Gold recovery exceeds (or is expected to) 95%.The Process Plant was designed and constructed under the supervision of Ausenco Engineering of Australia. Site works commenced in January 2004, Process Plant construction commenced in July 2004 and the first ore was presented to the Process Plant 26th February 2005. The first gold was poured on 15th March 2005. All construction contractors were demobilized from site 7th April 2005. Major achievements have been 3.4 million hrs LTI free during construction and operation to date, training of the Tanzanian workforce at Bulyanhulu Mine prior to commissioning, a succession plan to replace expatriate personnel with Tanzanian staff and significant over performance of the Process Plant against design.INTRODUCTIONTulawaka Mine is situated approximately 160 km south west of Mwanza in the western Lake Victoria Goldfields District of north western Tanzania. The property is held under a joint venture between Pangea Goldfields Inc (70%), a wholly owned subsidiary of Barrick Gold Corporation, and Explorations Minieres Du Nord Ltée (30%). A location map showing the position of the operation in Tanzania is shown in Figure 1.Mine site staff at Tulawaka comprises a combination of Tanzanian and Expatriate personnel. All Pangea personnel live on site and commute to their place of residence for their R&R on a 9 weeks on 4 weeks off roster."

Jan 1, 2006

Nickel-bearing ores in North-east Dundas have been described by A. McIntosh Reid1 as occurring at the margins of narrow dykes of gabbro, norite, peridodite and pyroxenite, which are intrusive into the Dundas series of slates, quartzites and breccias. They occur chiefly in the neighbourhood of the Five Mile, near Zeehan, as small, narrow ore-bodies which are mostly less than 100 ft. in length.The ores are massive sulphides containing pyrrhotite, chalcopyrite, pyrite and the nickel sulphide, pentlabdite.A less common nickel-bearing mineral, gersdorffite, has been recently found in an adit, which is marked on Reid's geological plan of Dundas as the Hecla mine, 30 chains south of the crossing of the North-east Dundas tramway, over the Great Northern Creek, and at an, elevation of about 350 ft. above the tramway. The occurrence is in a lode traversing the Dundas slates and quartzites, and is situated, according to Reid's plan, about 20 chains beyond the northern extremity of a narrow basic dyke which is continuous for a distance of two miles in a south-westerly direction.The mine eonsists of a prospecting adit following the course of a lode for about 275 ft. in a direction a little west of south. The low values of the lode are indicated by a bulk sample from a shallow winze about 100 ft. from the entrance which is reported by Reid to contain:

Jan 1, 1935

A Seismic Hazard Scale (SHS) has been developed to provide a practical seismic hazard assessment tool applicable to mine site personnel. It has been applied to seismic data sets from numerous Western Australian mines. The SHS is applicable when quantifying seismic hazard on a mine wide scale, on a mining block scale, and on a local cluster-by-cluster scale. Spatial mapping of variations in seismic hazard is a particularly powerful application of the scale. The SHS is sensitive to temporal increases in seismic hazard. It has also been shown that the SHS can be applied to estimate seismic hazard when seismic monitoring data are not available. The SHS is a simple derivation of the Gutenberg-Richter relation. There are assumptions and limitations to the SHS that need to be considered when applying it to mine seismicity data.

Jan 1, 2004

By Bruce Cantrell, K. L. Rubow

"INTRODOCTIONMeasurement of the contribution of diesel exhaust to respirable aerosol in mine environments has become increasingly important because of current concerns over the occupational health effects resulting from exposure to diesel emissions. In response to this, the U.S. Bureau of Mines is developing and evaluating new sampling methods for measuring diesel aerosol in underground mines. Two such techniques are being studied by the Bureau, size selective sampling and Chemical Mass Balance (CMB) modeling. These techniques use measurable physical or chemical characteristics of a mine aerosol sample to infer the amount of diesel particulate material contained in the sample.Size selective sampling is being adapted for measurement of diesel aerosol by the Particle Technology Laboratory (PTL) of the University of Minnesota under sponsorship by the Bureau. 1 It is based on the premise that diesel and mineral dust aerosol can be physically separated by size and collected during sampling using inertial impaction. An independent effort by the National Institute for Occupational Safety and Health to develop a size selective sampling technique was also sponsored by the Bureau.The second technique, CMB modeling, is being developed by the Bureau as an alternative measurement technique to referee the results obtained using size selective sampling.3 It compares measured trace element ""finger prints"" of aerosol sources with similar profiles of mine aerosol samples. From these, the portions of the sample contributed by each source can be determined. Results of these investigations in underground coal mines have confirmed that diesel and coal dust aerosol are of different size and can be measured separately using size selective sampling techniques.A major difference in diesel usage among underground mines is the requirement for exhaust gas cooling systems in coal and gassy noncoal mines. Nongassy mines usually employ limited exhaust conditioning in the form of catalytic converters, which have limited effect on primary exhaust particulate. The cooling system in most general use in gassy mines is the water scrubber. This device has little effect on most of the gases but removes particulate material from the exhaust. 5 Because of this, exhaust aerosol characteristics in nongassy mines are expected to be different. To see if size selective sampling techniques can be used in such mines, the Bureau and the University of Minnesota conducted a second study in three metal and nonmetal mines, two nongassy and one rated as gassy."

Jan 1, 1990

By Jørn H. Thomsen

This paper presents the experience gained and the lessons learned over the last decade within the numerous offshore foundation projects undertaken in the offshore waters of Denmark and Belgium by COWI A/S of Denmark. This experience derives from the close collaboration with, and interaction between the owners, contractors, and engineers in the various stages of project development. In turn, the experience draws on COWI's experience within foundation of large bridges world wide over half a century. Focus is on two pioneering gravity base foundation projects: ? Nysted in Denmark, currently the largest offshore windfarm worldwide with 72 Nos Bonus 2.3 MW turbines in water depths up to 10 m in the relatively benign inner Danish waters ? Thornton Bank in Belgium, where the first phase - comprising 6 Nos REpower 5MW-turbines of a total of 60 - are planned to be built in the rough North Sea in water depths exceeding 25 m.

Jan 1, 2013

By J. C. Ashby

Electric utility response to certain amendments of the Clean Air Act has resulted in a production of several types of alkaline coal combustion byproducts. Alkaline combustion byproducts are gaining increasing usage for acid mine drainage mitigation as research leads to a better understanding of their beneficial applications. Since January of 1997, Mettiki Coal Corporation has been injecting alkaline flue gas desulfurization material from Virginia Power's Mt. Storm Unit #3 wet limestone scrubber into abandoned portions of the active Mettiki mine. This paper provides an overview of the key design, transportation, regulatory, and environmental issues faced in the project.

Jan 1, 1998

By P. C. van Aswegen

The Bacterial Oxidation (BIOX®) process for the pre-treatment of refractory ores for gold recovery developed by Genmin, the mining division of Gencor, has been operating successfully at the Fairview mine since October 1986. The continuous operation of a pilot plant at Genmin Process Research has resulted in further process developments to improve plant operating efficiencies. These new developments which include a higher solids content of the pulp feed to BIOX®, lower retention times, higher operating temperatures, lower power utilization for oxygen dispersion .and reduced nutrient addition have all been successfully implemented on the Fairview plant.lt has furthermore been confirmed that the arsenic precipitate formed in the neutralization of effluent solutions complies to the United States of America EPA standards. Continuous cyanidation pilot plant work conducted on BIOX® product has indicated that cyanide consumption can be drastically decreased if a continuous flowsheet is implemented in preference to a batch leaching system.

Jan 1, 1991

By E Jak, M Shevchenko, E Nekhoroshev, D Shishin

In the field of pyrometallurgy, the presence of multiple molten phases with distinct chemical compositions, such as slags, mattes, speiss liquids, metals and molten salts, is a well-known phenomenon. These phases exhibit strongly non-ideal solution behaviour and are mutually miscible to varying degrees. To describe these complex molten liquids, the Modified Quasichemical Model (MQM) has proven effective and has been applied to numerous binary, ternary and several higher-order multicomponent systems related to pyrometallurgy. In recent decades, the complexity of high-temperature processes has escalated due to increased impurity concentrations in primary ores, the incorporation of recycled consumer products and the integration of metallurgical plants through by-product and waste exchanges. To address these issues, PYROSEARCH laboratory has been developing large 20-component thermodynamic database using a generalised CALPHAD (CALculation of PHAse Diagrams) methodology integrated with experimental investigations. Over the past decade, strategic decisions were made balancing the ability to generate experimental data, prediction power, accuracy, stability of calculations, as well as computational time, which are discussed in the paper. Examples provided for issues of >3 liquid immiscibility, non-ionic behaviour and exaggerated ‘sharp’ enthalpies of mixing in silicate slags, dealing with multiple oxidation states, as well as comparative analysis of pair and quadruplet approximation in MQM.

Aug 21, 2024

By S. Suwansawat, D. J. Maconochie, C. C. Chang

This paper describes the overall delivery of the tunneling for the Mass Rapid Transit Authority of Thailand’s Chaloem Ratchamongkhon Line in Bangkok and the constraints provided by the alignment. Eight earth pressure balance tunnel boring machines were employed under two major civil works contracts to drive approximately33 kilometers of tunnel in soft saturated ground beneath the crowded streets of Bangkok. Responsibility within the contract for building damage provided an inherent control for ground movement arising form tunneling when the right of way was narrower than the influence zone. These limits affect the earth pressure balance requirements and permissible ground loss. The methods adopted to limit ground movements and deal with the various obstacles to tunneling influenced the design and operation of the machines. The challenges provided by the need to tunnel through numerous lines of piled foundations of canal bridges and overpasses crossing the alignment are described.

Jan 1, 2001

By T. W. Johnson

One of the common methods of increasing recovery of oil from partly depleted oil sands is to inject natural gas, air, or air-gas mixtures into the sand, thereby supplying energy to move oil into the well bore. Where natural gas is not available, air or an air-gas mixture is used as the repressuring medium. Air-gas mixtures are obtained from the casing-heads of oil-producing wells in the areas repressured with air or air-gas mixtures and consist usually of varying amounts of the hydrocarbon gases, nitrogen, oxygen, and carbon dioxide. Laboratory experiments have been conducted by the Bureau of Mines to determine the effect of air on crude oils.4/ In these experiments the crude oils were oxidized by the air, and the degree of oxidation depended not only upon the chemical composition of the crude oil but also upon the duration and method of contact between the oil and air, the temperature of the fluids and the concentration of the oxygen. When the crude oils were oxidized the following results and changes in the oils were obtained:

Jan 1, 1937

The presence of gold or tin in a particular place in payable quantities may be suspected from geological and prospE;cting reports. It behoves the engineer by judiciously spaced boreholes or pits to establish whether the place is exploitable with profit, and it is the purpose of this paper to set out the ways in which this is done. The various types of deposit to be considered occur in Malaya, Thafland and Borneo, in which countries the writer spent four years in estimating alluvials.The methods described were used in actual practice both by the writer and previous engineers for the same company. The subsequent exploitation of the alluvials evaluated by the methods given below shows that the recovery was as good as, and sometimes higher than, expected. No claims are made to the originality of the methods, but it is 'felt that they may be new to some engineers and< interesting to others contemplating alluvial testing.

Jan 1, 1942

By D. Limpitlaw

The origins of mine closure practice have influenced the way in which it is implemented by companies and regulators. Mine closure practices essentially started developing in the 1970s in countries with advanced economies and mature mining industries. In these settings, the emphasis was justifiably placed on restoration of the landscape and an attempt was made to return to the ?natural? pre-mining land cover. These practices continued to evolve and incorporated socio-economic and cultural aspects, especially after the Brundtland Report in 1987 and the subsequent Earth Summit in 1992. Today mining is increasingly occurring in remote parts of developing countries where there may be significant need for infrastructure such as roads, clinics, and schools. The costs of returning land to low (economic) value pre-mining use may be far greater than establishing a viable postmining land use that could potentially add value to the community and take pressure off sites for greenfield development elsewhere. Furthermore, natural resource limitations (such as topsoil availability) may limit the degree to which the historical land cover can be re-established. Establishing post-mining land uses may aid in mitigating the loss of employment that is inevitable when mines close. Stakeholder participation in establishing post-mining land cover and land use options is critical for long-term success. Similarly, third parties must be identified to support the development of the post-mining land use This paper draws on the experience of the authors in several developing countries and presents a case for maximizing re-use of mining infrastructure. The paper does not advocate the adoption of poor rehabilitation standards, nor or the wholesale destruction of land capability, but rather leaving key infrastructure in place for post-mining use that may support sustainable development.

Jan 1, 2014

By L. H. Gevantman

A program for the compilation of evaluated physical and chemical numerical properties data is being pursued at the National Bureau of Standards within the Office of Standard Reference Data. This program is being sponsored by the Department of Energy and managed by the Battelle Office of Nuclear Waste Isolation in Columbus, Ohio. The intent is to assemble a reliable body of numerical properties data concerning candidate mineralogical materials in which high-level radioactive wastes are to be buried. The ready accessibility of the data to site designers and the credibility achieved through the evaluative process are designed to help assess and compare the feasibility of each candidate material for use as a disposal site. Both generic and site-specific data are to be assembled. To date, generic rock salt properties have been assembled and published by the NBS as NBS Monograph 167. Details of the effort to produce this book are discussed.

Jan 1, 1982

By William O. Vanderburg

This report3/ gives the reconnaissance of a reconnaissance of the mining districts in Churchill County, Nev., made in the fall of 1938 and spring of 1938 All of the mining districts in the county were visited, but no attempt has been made to include all the mines and prospects within the area; inclusion or omission of a property in this paper has no bearing on its merits, The report gives the situation of the various districts, mineral production, and ownership of properties; describes the ore deposit, mines, and prospects; contains information on past and current activity; and includes other data likely to be useful to those interested in the development of our mineral resources. The various district, were named when they were organized for purposes of record and regulation. When established, the districts embraced large areas n without well- defined borders, so that the names have little geographical significance.

Jan 1, 1940

By Albert J. Forney

Extensive studies have been made of the various effluents found in the Synthane coal-to-gas process. Analyses have been made of the waters, gases, and trace elements present in some of the streams. Results of analyses show the water effluents are the area where extensive research is needed.

Jan 1, 1974

By P. O'Connell, J. Lever, C. Clemence

The Bulyanhulu Mine, Tanzania is constantly trialing ideas for improvements in the drill and blast process. The project work has resulted in a large number of choices in explosive type and charging methods being available for blast design. Interestingly, though booster sensitive bulk emulsion had been introduced to the site to reduce dilution, better results were being obtained from reduced charge columns (decoupled columns of poured anfo in 50mm pvc pipe) and pneumatically loaded anfo upholes, which had been traced. In order to compare the explosive type and charge up-methods, an explosives comparison trial was performed.

Jan 1, 2006

By Y. H. C. Wang

A detailed study of carrier flotation of kaolin clay using calcite showed the major beneficiation mechanism to be enhanced aggregation between anatase and calcite under intense agitation conditions. In order to develop an understanding of this selective aggregation, surface charge characteristics of kaolinite, anatase and calcite were studied under simulated flotation conditions. Zeta potential of all these minerals tended towards a constant negative value in ole- ate solutions under certain conditions possibly due to adsorption or precipitation of oleate on them. However, whereas the zeta potential of anatase in the oleate solutions was not influenced by the agitation level, that of kaolinite was found to be strongly dependent on the agitation intensity. The effect of oleate on zeta potential of kaolinite was reduced by an increase in agitation intensity. It is suggested that oleate is much more firmly bound to the surface of the anatase and that this preferential attachment is responsible for the enhanced selective aggregation of the anatase with calcite. Agitation level plays a major role in carrier flotation since intense agitation is considered to en- hance both the chemisorption of oleate on anatase and preferential detachment of calcium oleate precipitate from the kaolinite surface, all of this producing a large difference in the surface properties of anatase and kaolinite, and hence in their tendency to aggregate with calcite.

Jan 1, 1981