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By T Martin, M Martin

Mining of sulfide-based ore deposits typically creates a potential for release sulfate and acid to groundwater, and many operating mines are thus predicted to require long-term post-closure treatment of groundwater. Toward the goal of selecting an optimal treatment, this paper compares costs of four demonstrated technologies for long-term treatment of sulfate-contaminated groundwater: in situ biological reduction (ISR), in situ permeable reactive barrier (PRB) composed of compost and zero-valent iron (ZVI), and two ex situ æpump-and-treatÆ technologies ù ex situ biological reduction, and ex situ nanofiltration with lime precipitation. Costs for each technology are estimated for treatment of a model aquifer system containing sulfate-contaminated groundwater, with the goal of treating 1 m3/min of groundwater from 1500 mg/L sulfate to a target level of 500 mg/L. (Metal removal is typically achieved by these technologies, and thus excluded from this analysis.) Costs are estimated for each technology as a function of treatment duration (ten to 60 years) and, for PRB and ISR, required replacement frequency (ten to 60 years). Estimated costs include capital and operation and maintenance, using a seven per cent net discount rate. Results indicate that ex situ technologies (biological reduction and nanofiltration with lime precipitation) are the most expensive. In situ technologies may be much less expensive, with PRBs having by far the lowest potential cost, followed by ISR as the next least expensive. However, actual costs for the in situ technologies are very sensitive to poorly constrained parameters, particularly the ZVI content of the PRB, and the effective life of PRB and ISR systems. This large cost uncertainty supports delaying remedial actions where viable, and suggests that feasibility analyses are generally warranted for specific applications to focus on these sources of uncertainty.

Jan 1, 2003

By T. R. A. Davey

A Survey of current and recent research and developmental work is supplemented by predictions for processes which should be developed over the remainder of this century.

Jan 1, 1970

Low-grade manganese ore from Sandur, India containing 28.2 per cent manganese and 20.9 per cent iron was roasted with sulphating agents, viz ammonium sulphate and sulphuric acid. The effects of temperature of roasting (300 - 800°C), time (15 - 120 minutes) and amount of sulphating agent (0.5 to 2.5 times stoichiometric amount) were studied. Under optimum conditions, it was possible to extract 92 per cent manganese with 0.5 per cent iron at a temperature of 700°C for 90 minutes duration with stoichiometric ammonium sulphate. Further increase in quantity of ammonium sulphate has marginal effect on manganese extraction.Similar studies were carried out with sulphuric acid, and an extraction of about 87 per cent manganese with similar iron contamination was achieved at a temperature of 700°C for 60 minutes duration with stoichiometric quantity of the reagent. Selective extraction of manganese with respect to iron is discussed.

Jan 1, 1996

By S Ramsay, D Povey

This paper presents recent case study data collected by field portable x-ray fluorescence spectrum analysers (FPXRF) as part of grade control activities at three separate (nickel, copper and copper/gold) mining operations. FPXRF has been under utilised for grade control in recent years, largely because the success of early versions of FPXRF was limited to a few metals (eg tin). Efforts to utilise these early versions for other metals was largely unsuccessful and created a perception that FPXRF could not be utilised more broadly within the mining sector and specifically the area of grade control. The structural setting of the analytical function within mining operations has also contributed to the under utilisation of more recent FPXRF instrumentation. The concept of FPXRF as a grade control tool straddles the boundaries of the geology and laboratory departments. As such, this option is often not considered as part of an assessment of grade control procedures for new and existing mining operations. This paper assesses data collected by Australian and New Caledonian miners using FPXRF technology as part of the grade control function and concludes that FPXRF can provide operational and cost benefits to certain mining operations.

Jan 1, 2003

This part of the final report treats some problems related to coal mine carrier frequency communication systems using the trolley wire/track transmission line. This work was undertaken for a brief period of time during the summer of 1972 to help understand, quantify, and improve some of the trolley wire carrier system behavior observed and/or predicted. Calculations and estimates of transmission line characteristic impedance, inductance and capacitance per unit length, mine motor loading effects, parallel line effects, and connection impedances are presented in Chapter I. Chapter II treats the design of r-f isolators for reducing the undesired and troublesome r-f loading that mine motors present to the trolley transmission line. Chapter III treats a diversity method for combatting standing wave nulls. I. CALCULATIONS RELATED TO TROLLEY WIRE COMMUNICATIONS A. ESTIMATION OF INDUCTANCE AND CAPACITANCE PER UNIT LENGTH OF TROLLEY LINES To estimate the L and C per unit length of trolley lines, we use the eccentric line model of Section G of this Chapter, "Characteristic Imped¬ance Estimates for Mine Trolley Lines." The capacitance per unit length for an eccentric line is given by (1)

Jan 1, 1974

By Paul S. Lewis

The Bureau of Mines hydrogenated coals of different rank that had been irradiated with either x-rays or gamma rays. Lignite, high-volatile A and C bituminous, and low-volatile bituminous coals were exposed to l billion roent¬gens of gamma-ray radiation; specimens of high-volatile A and C bituminous coals from other sources received 6 million roentgens of X-ray radiation. Irradiated and unirradiated control specimens of those coals were hydrogenated in autoclave experiments at (6,000-p.s.i. final pressure and 400° C. with retention times of 15, 30, or 60 minutes depending on the coal rank and catalytic treatment. Comparison of results from irradiated specimens with those from the control experiments showed that the radiation had no beneficial effect on the coal. High-volatile C bituminous coal may have been affected by radiation more than the other coals. One billion roentgens appeared to reduce the amount of coal converted to liquids and gases by about 10 pct., and 6 million roentgens reduced it by about 6 pct. then catalyzed with tin. In all other cases, the conversion of irradiated coal was either reduced by as much as 4 pct. or was essentially the sank as that obtained with unirradiated coal. Irradiation during hydrogenation nay be effective for increasing the reactivity of coal and should be investigated; further work with coals irradiated prier to hydrogenation is not recommended.

Jan 1, 1962

By Kurt R. P Petersen

This paper discusses the current approaches to modelling the DMS cyclone within the De Beers group. Current efforts are split into short term value-adding process understanding and longer term semi-fundamental analysis of separation mechanisms. To date, the basic applied approach has yielded significant value to the group, enabling operators to focus on simple diagnostic measures to control their process. The more involved modelling approach has given rise to a new understanding of the separation field, in particular that the high density gradients within a cyclone are highly localised, indicating that separation of medium to heavy density material takes place low in the cone. The model has proven to be conceptually robust, but still requires further development and validation to become a complete modelling and simulation tool for De Beers.

Jan 1, 2006

By J Lyall Workman, Larry R. Fletcher

Blasting methods have been proposed for reclaiming abandoned underground coal mine sites having unstable conditions. The objective of blasting is twofold: the permanent stabilization of an area by the collapse of underground workings to prevent any future subsidence, and the use of blasting to close existing sinkholes.

Jan 1, 1991

By K. [Muthukkumaran

An extensive program of laboratory model tests was undertaken to study the effect of slope on p-y curves under passive loading in dry sand. The paper concerns the method developed in a series of laboratory model tests to experimentally determine p-y curves. Bending moment curves are differentiated by using curve fitting method of cubic polynomial function. The study includes effect of slope angle and relative density on bending moment and non-dimensional p-y curves. The non-dimensional p-y curves for piles on sloping ground under passive load are developed modifying API method by including a Reduction Factor (R) using the experimental results.

Jan 1, 2006

By Brahm D. Prasad

As in other mineral deposits, variation in bitumen saturation, thickness of ore and discard occurs throughout Alberta's Athabasca Oil Sands deposit. The economic stripping ratio developed here to determine surface mineable limits takes into account capital and operating costs, crude oil prices, quality of ore, thickness of overburden, and thickness of inter-ore waste. The surface mining systems employed to remove bituminous sands (oil sands) from huge mines at depths of 60-70m use gigantic draglines, bucket wheel excavators and reclaimers, and large mobile equipment.

Jan 1, 1982

By John W. Brown

The purpose of this paper is to describe different methods of evaluating the performance of your current rotary blast hole drills. To properly evaluate a drill rig's performance you should include a competent driller, mechanic, rotary bit technician and a technician representing the manufacturer of the drill.

Jan 1, 1998

By D. Yamada, T. Tanaka, N. Inouchi, J. Nakahigashi, H. Yoshimura, T. Nonishi

The use of cereal food materials as lubricants was investigated in an attempt to develop nonpolluting lubricants. Suspensions of wheat flour in water and other types of cereal food lubricants were prepared and their friction coefficients measured. The results indicate that a cereal food lubricant containing 30% lipids, 2% proteins, 60% carbohydrates and 0.6% calcium carbonates has the lowest friction coefficient for a sheet (cpTi-1). As example applications, the lubricant was tested with a forming press and a screw-fastening device. In both applications the cereal food lubricant performed relatively well in comparison to conventional lubricants and thereby has potential for practical applications.

Jan 1, 2006

By J. C. Norman

The United States was the world’s largest producer and consumer of boron compounds during 1995. According to estimates from the US Geological Survey(USGS), boron mineral concentrate and chemical production in the United States totaled an estimated 1.1 Mt(1.2 million st) yielding 602 kt (663,000 st) of B2O3 for an estimated value of $462 million. This level of production exceeded 1994 revised production figures by about 9%. The United States continued to provide nearly all its own boron supply while maintaining a strong position as a source of sodium borate products and boric acid to foreign markets. During 1995, about 900 people worked in domestic boron mines and plants, about the same as in1994. USGS estimated total world production of boron during 1995 to be about 3 Mt (3.3 million st), yielding about 1.6 Mt (1.8 million st) of B2O3. World production in 1995 was about equal to revised 1994 levels.

Jan 1, 1996

By C. Karpuz, Y. S. Istanbulluoglu

This paper describes the results of convergence measurements conducted about five years for the re-use gate roadways at OAL lignite mine in Turkey. Double lignite seams separated with a marn layer, are mined with long-wall retreating mining system at the mine. Rib pillar has been abandoned and gate roadways were planned to be packed for the re-use of full extraction. Various packing systems have been attempted, namely three rows of woodenchock, one row of wooden chock plus concrete wall and concrete wall only. The re-use of maingate roadways packed with wooden chock yielded 62% of closure. Lastly developed concrete packing of 3 meters wide and specially developed support set composed of three friction props and a cap, which is a modification of yieldable set, have successfully maintained the main and tail gate roadways stability with a total vertical convergence of 32%. Good correlation has been established between pack stiffness and floor heave as well as maingate and tailgate convergences. The elimination of rib pillars by re-use of gate roadways increased the coal recovery by 20% and decreased the development/production ratio from 0.065 m3/ton to0.022 m3/ton.

Jan 1, 1997

By Bill Zietlow

A micropile and soil nail underpinning system was installed to support a building immediately adjacent to a 25-ft deep excavation in downtown Salt Lake City, Utah. Both the building and the underpinning were instrumented to monitor deflections, rotation and crack growth. The underpinned structure consisted of a two story concrete masonry unit (CMU) building founded on shallow spread footings attached to a concrete high-rise building on spread footing two floors below grade. The face of the excavation was 10 in. in front of the underpinned building foundation wall. The underpinning system consisted of small diameter hollow bar micropiles installed with injection grouting techniques below the bottom of the excavation and attached to the underpinned structure by a concrete pile cap doweled into the existing footing. The lateral loads imposed by the soil under the underpinned structure were designed to be supported by the soil nail wall installed through the micropiles during excavation. The settlement monitoring instruments consisted of crack gages, optical survey prisms, high sensitivity vibrating wire water levels and biaxial vibrating wire tilt meters. They recorded maximum movements of approximately 0.1 in. of settlement, 0.05 deg. rotation (top of wall rotating away from excavation) and up to 0.08 in. of crack opening during the excavation until one month after the soil nails and shotcrete facing were completely installed. This movement was well within both the estimated settlement and the estimated settlement tolerance of the underpinned structure.

Jan 1, 2008

By W. Z. Rogers

U.S. feldspar output sold or used in 2004 was estimated to be 790 kt (871,000 st), valued at $43 million free-on-board plant. This was below 2003 and about the same volume as 2002. The strong housing market in the United States maintained demand for ceramic tiles, plumbing fixtures, and fiberglass insulation requiring feldspar and shipments of glass containers increased by about 4 percent. Imports of ceramic tiles and plumbing fixtures continue to increase, taking the place of U.S. produced goods, and the feldspar required to make them. Output included flotation concentrates, feldspar content in feldspar-silica mixtures, potash feldspar and aplite.

Jan 1, 2005

By Stanley O. Reichert

At nuclear facilities, three types of radioactive waste must be managed: (1) high-level liquid waste containing fission products from the chemical separation of irradiated uranium, (2) low-level condensates from the concentration of the high-level waste, and (3) dry solids such as obsolete process equipment, spent ion exchange resins, and irradiated metal scrap. The geological and environmental characteristics of a site are important considerations in planning the waste management program. At the Savannah River Plant, low-level liquids and dry solids are safely and economically placed in the soil where the geologic and hydrologic conditions are favorable. Within the general area where the waste originates, studies are made to locate seepage basins and burial grounds in the most favorable sites: (1) soils should have a high ion exchange capacity and moderate to low permeability, (2) the water table should be deep, and (3) burial sites should be relatively distant from the nearest flowing stream.

Jan 1, 1968

By Wei Bin, Liu Zhe, Liping Xiao, Jichi Bai

The Acid Mine Drainage has characteristics of low pH, high concentrations of heavy metal ions, such as Fe2+, Mn2+, Cu2+ and Zn2+. In this paper, the composite particles that consisted of bentonite and steel slags were used to dispose the Acid Mine Drainage. Bentonite is the mineral materials and can adsorb heavy metal ions excellently. The steel slags are alkaline and industrial solid waste for the treatment of the Acid Mine Drainage. The main influencing factors, such as adsorbent dosages, shaking rates, concentrations of heavy metal ions, temperatures, adsorption time and pH value were studied by the static experiment. Increasing the adsorbent dosages and the concentrations of the heavy metal ions, speeding up the shaking rates, raising the temperatures, extending the adsorption time and improving pH would improve the removal efficiencies of heavy metal ions. Through considering the removal efficiencies and the treatment costs, the optimum reaction conditions for the four kinds of heavy metal ions were obtained. The adsorbent dosage 21 mg/L, the rotational speed 120 r / min, the temperature 25?, adsorption time 100 min and the initial wastewater pH 7. The four kinds of heavy metal ions existed independently in the simulated mine wastewater. The highest initial concentrations of Fe2+, Mn2+, Cu2+ and Zn2+ were 150 mg/L, 100 mg/L, 170 mg/L and 140 mg/L respectively. The removal rates were 93.42%, 92.64%, 93.86% and 95.17% respectively. The determination of the particles’ SEM-EDS Microscopic characterization showed the composite particles could play a part in neutralizing, absorbing and the chemical precipitation. The acidity decreased notably and the heavy metal ions of Fe2+, Mn2+, Cu2+ and Zn2+were adsorbed and precipitated effectively. The research results can extend the practical engineering application of the composite particles.

Jan 1, 2017

By A. Bois-Brochu, G. Morin, G. Marin, M. C. Parr, J. Carignan

The presence of an alpha case on titanium parts produced by investment casting is problematic and has to be eliminated. The traditional techniques for the evaluation of its thickness are metallographic measurements and micro-hardness profiles. To obtain a better understanding of how the alpha case is formed with the underlying objective of limiting its depth, the present study proposes to characterize the microstructure and the chemical composition of the alpha case. Electron microprobe analyzer (EMPA) linescans were used to quantify the oxygen and substitutional elements that come from the mould and promote the alpha case formation. The chemical profiles were correlated with metallographic and microhardness measurements. For microstructure, optical microscopy (etched and polarized light analysis) was used. For phase analysis, samples were mechanically polished step by step and analysed using X-ray diffraction and optical microscopy. Furthermore, surface analysis techniques such as XPS and Auger Microscopy were evaluated but results were found to be inconclusive because the formation of the oxide layer was faster than its ablation and the matrix could thus not be analysed. The alpha case was observed on a Ti-6Al-4V step block casting.

Jan 1, 2014

By P. V. Ananthapadmanabhan

Feedstock powders of metals, alloys and ceramics for thermal spray applications have to meet several specifications. Particle shape, size and distribution, powder flow characteristics and density are the important factors that need to be controlled, in order to ensure high spray efficiency and better coating properties. Thermal plasma technology can be effectively utilized to produce metal, alloy and ceramic powders for spray applications. The present paper describes plasma spheroidisation of commercially available aluminium powder and nickel-aluminium powder blend in a plasma reactor. Results show that the processed powder particles bear spherical morphology with excellent flow characteristics, which make them ideal for thermal spray applications.

Jan 1, 1997