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By T. D. Maki

FMC Gold's Paradise Peak Mine, located 13 km (8 miles) south of Gabbs, Nevada, became operational in April of 1986. Shortly thereafter heap leach testwork began on sub mill grade ore. Presently, testwork continues in combination with production size heaps that account for approximately 6% of total gold production at Paradise Peak.

Jan 1, 1989

By Rodolfo V. de la Cruz

This paper describes the development of a modified Goodman Jack method for determining the mechanical properties of rock masses in situ. The modified method consists of the basic borehole loading device and a friction-strain-gauge measuring module. The friction gauges, located in the central portion of the jack, are impressed on opposite quadrants of the borehole walls and the remaining quadrants are loaded by the borehole jack with a uniaxial self-equilibrating pair of forces. The tangential strains generated at the borehole walls are thus measured concurrently with the loading. For ideal elastic materials, the tangential stresses at any point on the borehole walls due to jack loading can be obtained from closed-form analytical solutions utilizing the complex variable method. Complete stress-strain curves for the rock material can then be directly obtained from the tangential strain measurements and the calculated tangential stresses at those points. The continuous data are considerably more significant and reliable than averaged or point data obtainable by other current in situ measuring techniques. Moreover, the advantages inherent to the original Goodman Jack method are also obtainable in the modified method. The suitability of the new method was demonstrated by carrying out a number of laboratory measurements in large specimens of reinforced concrete, aluminum and granite blocks. The results of actual field measurements carried out in sandstone and granite quarries were found comparable with those obtained in the laboratory.

Jan 1, 1976

By V. C. Rogers, K. K. Nielson

INTRODUCTION An evaluation of the radiological health risks from uranium mining and milling requires the determination of several key parameters. As shown in Figure 1, the first step is the estimation of the radioactive source term. The radionuclides in the ore consist of the 238U decay series nuclides shown in Figure 2, the 235U series nuclides, and 40K. The 238U decay series isotopes dominate the source term, with the 235U series isotopes causing less concern and 40K remaining at background levels. [ ] Specifically, the risks from uranium mining and milling are mainly associated with 230Th, 226Ra, 222Rn, and its short-lived daughters. These radioisotopes are mainly alpha-particle emitters; hence, some dispersion mechanism is necessary to bring them into intimate contact with man so that they can be inhaled or ingested For water pathways, the leaching of the isotopes from [ ] the solid ore or tailings provides a measure of the amount of contaminant initially available to the environment. For the air pathway, dust-creation mechanisms such as blasting, crushing or general resuspension processes dominate for 226Ra and 230Th. However, 222Rn, being a chemically inert gas generated from the decay of 226Ra, can migrate through the ore, overburden and tailings over considerable distances. As shown in Figure 1, the next step in the pathway to man is environmental dilution and delay. For the water transport mechanism, the delay in the isotopes reaching an accessible water supply may be considerable (several thousand years or more), but for airborne nuclides the dispersion in the atmosphere is rapid and constitutes the main mitigating factor. Considerable ventilation is provided in underground mines to dilute and remove radon and its daughters in order to keep their concentrations low and thereby minimize their inhalation by miners. The rate of uptake by both the workers and the general public is often difficult to ascertain. It involves breathing rates, rates of water consumption and other poorly-defined parameters. The final steps are the risk estimators used to predict doses and cancer rates from the inhaled radon daughters and ingested or inhaled radium. Many

Jan 1, 1981

By V. Osterholt

Sustainable development of mineral resources is based on a spatial model of the orebody that is only partly known from exploration drilling and associated geological interpretations. As a result, orebody models generated from the available information are uncertain and require the use of stochastic conditional simulation technique. This paper considers three methods for simulating orebody geology: (1) pluri-Gaussian simulation that limits the allowable contacts between the various units; (2) sequential indicator simulation using indicator kriging; and (3) an experimental multiple-point approach that captures some higher-order spatial statistics. The data requirements of the methods, how to meet them in mining applications, and performance characteristics are discussed. The application of these methods in a hypothetical deposit consisting of three geological units provides a comparison and illustrates the advantages of the different simulation approaches.

Jan 1, 2005

By W. E. Cobb

The financial implications of environmental liabilities are becoming staggering, particularly for mining companies. The Environmental Protection Agency's (EPA) Record of Decision (ROD) list for Superfund mining sites has some pretty hefty financial commitments, such as the $10 million operable unit remedy for the Yak Tunnel at California Gulch (in Colorado) or the $40 to 60 million remediation at Bunker Hill (in Idaho). These costs are driven by the large volume and areal extent associated with historical waste management practices at mining sites. (It's difficult to have a low-cost remedy for a 20-square-mile site.) Unfortunately, there are other ways of generating environmental liabilities besides Superfund, such as non-compliance with Clean Air Act provisions, stormwater permits, or National Pollutant Discharge Elimination System (NPDES) permits. In the last 2 years, EPA has increased enforcement in its regulatory programs, which has resulted in increased fines and criminal actions. Leaders in other industries (primarily the chemical and manufacturing industries) are viewing environmental liabilities as a strong motivator to select engineering approaches carefully based on technical, legal, economic, and philosophical perspectives. Industry interest in waste minimization programs comes from the concept that it is economically advantageous not to create waste in the first place. Waste minimization programs typically balance increased front-end capital investment with the minimization of potential long-term environmental liabilities as a way to achieve the lowest total-or life-cycle-cost. A side benefit of waste minimization programs is that they tend to improve overall regulatory compliance. Waste management practices are also becoming philosophical, as evidenced by a May 11, 1992, Business Week article: Companies that incorporate innovative thinking on sustainable development will do more than clean up or prevent their own pollution. They'll make and distribute a product more efficiently than ever, worry about its lifelong environmental impact, plan for recycling, and get their suppliers on the bandwagon. This type of approach will require a new mind-set, new tools, and adjustments throughout the organization. A key aspect of waste minimization or life-cycle waste management programs is the incorporation of environmental costs into economic analyses that compare various waste management alternatives. However, the incorporation of environmental costs into an economic analysis can be more difficult than initially thought. As noted above, new tools-or even a new toolbag-are needed, such as new accounting methods that track and assign the true lifetime environmental costs of a particular product. One piece of the new toolbag is life-cycle cost analysis, which is discussed in this paper. To simplify the discussion, this paper looks at the total costs associated with a given mining site. The concepts presented in this paper, however, can be applied to any mine waste management decision. The ultimate extension of life-cycle costing, as presented in the Business Week article, is to include the potential environmental costs throughout the life of a metal. At this point, I am perplexed on why, let alone how, to include the potential downstream environmental costs (i.e., the costs associated with smelting, manufacturing, use, and recycle or disposal) throughout the life cycle of mined copper, lead, or zinc.

Jan 1, 1992

By R. Frenette, A. W. Mo, H. A. Hamza

Fine particles present major technical and economic problems to those who deal with solid/liquid separation processes. In the coal industry the problem is compounded by the large amounts of produced fines such as those present in Western Canadian coals. Flocculants in the form of high molecular weight water soluble polymers are commonly considered an effective solution for the enhancement of the separation process. These reagents are relatively expensive especially when considering a low-price commodity such as coal. Optimization of the use of these reagents is therefore an operational necessity. Six polymers were evaluated as to their effectiveness in flocculating a fine coal tailing. Results were compared with those for a reference flocculant, in-use at that time in the washery. It was shown that, in general, flocculants significantly improve the solid/liquid separation process. The ranking of the flocculants as to their effectiveness in settling and filtration indicated that the best flocculants for settling were not necessarily the most effective for filtration. Flocculants that showed the best filtration improvement were generally cationic and those best for settling were anionic.

Jan 1, 1988

The Waste Isolation Pilot Plant (WIPP) is a geologic repository for disposal of transuranic waste and is operated by the US Department of Energy. The repository is located at a depth of 655 min the Permian age salt beds of the Salado Formation. The exhaust air from the facility is independently monitored by the Environmental Evaluation Group to verify compliance with regulatory release limits for radioactive materials. A May 1995 video inspection of the exhaust shaft identified fluid migration into the uppermost 25 m of the shaft. Since then, water has been observed flowing in from cracks in the shaft lining between 16and 25 m below surface level at an estimated rate of between 5 and15 m3/d. This water inflow has not only negatively impacted the equipment in the shaft, associated duct-work and monitoring equipment located at the top of the shaft, but also challenged efforts to verify compliance at the WIPP. This paper provides an analysis of these effects.

Jan 1, 2004

By G. Trusler, P. Dama, C. Buckley, C. Jänisch

In the 1990s, Cleaner Production (CP) approaches were successfully introduced to a number of industrial sectors in South Africa. Building on this success, the South African Water Research Commission has commissioned a 3-year study to investigate the use of CP and its related set of environmental assessment and management tools in the mining industry. A scoping study is being carried out on the current knowledge of CP approaches being used in the industry, as well as the proactive and preventative measures being undertaken. One of the significant findings of the scoping study is that distinct differences exist between the larger global companies and the smaller local companies. Being a water research project a key focus area of the project is to reduce the impacts related to mining on the South African water resources. Some of the significant water related threats identified include acid mine drainage, the shortage of the resource and the effects of inter-mine flow.

Jan 1, 2005

On Feb. 16, 2012, the Polish coal mining company Lubelski Wegiel Bogdanka S.A. set the world record for daily production from a plow-equipped longwall, with an output of 24.4 kt (26,900 st) of coal from a single face. The company commissioned the first Cat longwall system at its Bogdanka Mine, near Lublin in eastern Poland, in March 2010 and within six months had raised the bar to nearly 17 kt/d (18,700 stpd) of cut coal. Since then, Bogdanka has continued to increase its daily output with a plow face that began mining in the new 7/VII/385 panel last October, taking the world record to new levels. In addition to the record output achievement, the plow face advanced more than 27 m (89 ft) at a 1.63-m- (5.3-ft-) cutting height. ?We thought this achievement would be impossible for any shearer in seam heights as low as this,? said Zbigniew Stopa, vice president of Bogdanka.

Jan 1, 2012

By Zachary E. Wedding, Zach Agioutantis

Excavation of underground openings results in the redistribution of the in situ stress into the rock adjacent to the opening. Stress redistribution depends on opening geometry, pillar geometry, material properties, possible confinement, and constitutive models describing the behavior of adjacent rock. This paper presents typical pillar stress distributions for elastic and yielding pillars as a function of opening geometry, material properties, and material constitutive models and highlights the differences between them. Stress distributions are compared with empirical strength profiles that have been developed for coal pillars as well as actual pillar geometries documented for stone pillars.

Jul 1, 2023

The nature of adsorbed calcium carboxylates (oleate and stearate) has been investigated by in-situ/ex-situ Fourier transform infrared internal reflection spectroscopy (FTIR/IRS). Previous spectroscopic studies in alkaline solution have shown that adsorbed carboxylate is characterized by a C-O stretching vibration at about 1550 em?1 for less than monolayer coverage. Similar results were found in this study. More specifically, in this study such a singlet at 1550 cm-1 was found for LB monolayers of calcium distearate transferred as a condensed layer at a high film pressure to the surfaces of fluorite and germanium. Normally the spectrum of bulk calcium distearate reveals a doublet at 1575 and 1540 cm-1, characteristic of a three dimensional 7-fold coordination for calcium carboxylate complexes. This doublet is generally found for carboxylate multilayers formed by spontaneous adsorption at the surface of calcium minerals. In this regard, the spectral evidence suggests that whenever the calcium dicarboxylate is constrained at a surface as a condensed layer, the 7-fold coordination can not be satisfied and the surface carboxylate is forced into a two dimensional symmetrical coordination with a singlet at 1550 cm-1. On the other hand, if the Langmuir-Blodgett (LB) monolayer calcium distearate film is transferred at a low film pressure the doublet is observed. This analysis is further confirmed by the spectral results for LB transferred calcium distearate monolayers at a hydrophobic silicon surface. Even though these are condensed monolayers formed at high film pressure, the carboxylate group, oriented away from the surface, is no longer constrained by the surface force field, and thus exhibits the characteristic doublet of the bulk calcium distearate salt.

Jan 1, 1998

By Antonio Rivera

On Nov. 13, 1985, Colombia's Ruiz volcano erupted, killing an estimated 25,000 people and burying several villages. Damages were estimated to be about $US300 million. The following is an account by SME member Antonio Rivera of the volcanic activity that led to the eruption. His account also includes a description of the geography and some geology of the affected area. Mining operations in the area were mostly unaffected, although some operations were forced to close until the roads leading to them could be repaired. Introduction The Ruiz volcano is located on the Central Cordillera of Colombia about 28 km (17 miles) southeast of Manizales, the capital of the state of Caldas. Ruiz is one of nine volcanoes that form a complex volcanic chain within the middle portion of the Central Cordillera. The Cordillera has 30 other volcanoes in the southern part of Colombia. Ruiz volcano Ruiz's elevation is 5200 m (17,060 ft). It is covered by an ice cap estimated to be 20 m (66 ft) thick at its summit, an area that covers 17 km2 (6.5 sq miles). Drainage is composed of several rivers that flow into the Magdalena River on the east and Cauca River on the west. The rivers flowing to the east are Guali, Azufrado, Lagunillas, and Recio. The rivers that flow to the west are Claro, Molinos, and Chinchina. There is a road from Manizales to El Refugio, a ski area located on the northeast flank of the volcano at 4800 m (15,750 ft) in elevation. The Ruiz volcanic complex was built in two stages. The first is a shield type of volcano (mainly lavas) formed about a million years ago. The second is a younger stratovolcano overlaying the ancient one. It consists of lavas and pyroclastics and was built over the past 500,000 years. Twenty-four eruptions of Ruiz are known to have occurred during the last 14,000 years. Its products mainly consist of lava flows, pyroclastic flows, mudflows (lahars), and directed lateral explosions. Historic eruptive record 1595 - Debris avalanche, blast, pyroclastic flows, mudflows, ash flows, and ash fall. 1828-1829 - Ashes (phreatic). 1831-1833 - Gas emissions and ashes. 1845 - Mudflows and pyroclastic flows. 1985 - Sept. 11- Fumarolic activity, phreatic eruption, ash fall, and small mudflows. 1985 - Nov. 13 - Ash and pyroclastic fall, major destructive mudflows (magmato-phreatic eruption). From 1845 through 1984, Ruiz volcano always had a slight fumarolic activity. It was restricted to the crater area. In November and December 1984, the fumarolic activity increased and the first ash emission and vapor-sulfur formation started. Small local earthquakes accompanied these volcanic activities. The volcano had a small erup¬tion on Sept. 11, 1985. It was manifested by phreatic explosions that ejected fragments of the vent and formed ash deposits 25 mm (1 in.) thick around an area 2.5 km (1.5 miles) from the crater. Fine material was blown by the wind and reached Manizales and neighboring areas, producing a small layer of ash up to 10 mm (0.4 in.) thick.

Jan 2, 1986

By Dr. Jagdish C. Agarwal

Kennecott Copper Corporation has developed a new hydrometallurgical process for extracting nickel, copper, cobalt and molybdenum from maganese nodules. This process (KCC Cuprion Process) utilizes a reduction leach operating at atmospheric pressure in the temperature range of 45 C to 50 C and has been successfully demonstrated in a continuous pilot plant processing 800 lbs of nodule ore per day. The chemistry, basic flow sheet and operating characteristics are presented and discussed.

Jan 1, 1978

By Colin C. Harris, Jie Zheng

While applications of stirred media mills for fine particle production have continued to increase, there is a lack of understanding of operating behavior and power requirement. Investigations in laboratory stirred media mills have been carried out with grinding media, limestone and yttria stabilized zirconia. The torque required to rotate impellers immersed in dense particulate media with supernatant versus impeller rotational speed displays four regions marked by sharp transitions: transition from static to dynamic friction; channel- ling; dispersing; and centrifuging. Equations, including dimension- less group correlations of power and modified Reynolds number, for relating power, speed, impeller and tank dimensions and design, media size and density, solid concentration, and other relevant variables have been established. Scale-up guidelines with respect to power consumption are also proposed. The best operating conditions for grinding limestone in the laboratory stirred media mill have been identified. Complexation by the polymer during ultrafine grinding of zirconia has been found to cause extraction of yttrium into solution with possibly significant changes in the surface chemical composition of the product.

Jan 1, 1995

By M. Trim, Y. Sun, D. Tepavac, A. Kumar

Configuration of Rozelle Interchange Project’s ventilation system required design and construction of some of the largest and tallest underground civil caverns attempted in Australia. The paper focuses on the technical challenges of designing these caverns within a heterogeneous, generally weak sandstone under highstress conditions while providing a construction sequence that would align with the contractor’s preferred techniques and schedule. Various construction techniques were investigated, but ultimately an observational approach relying on a construction sequence and specialized instrumentation met both the designer’s and contractor’s requirements. Relevant data obtained from excavations and the construction monitoring program are presented within.

Dec 1, 2022

By Todd Wanless, Daryl Poduska, Prakash Donde, Mahmood Khwaja

"The proposed Minne Lusa Stormwater Conveyance Sewer is part of the Phase 3 Major Combined Sewer Overflow projects to be scheduled as part of the City of Omaha’s Long Term Control Plan (LTCP). The system features a 6,100 foot long, 14-foot inside diameter tunnel to provide for conveyance of separated stormwater from previously completed and future LTCP sewer separation projects to the expanded Storz West and Pershing Detention Basins and subsequently, the Missouri River. The tunnel will operate as a pressurized system and convey flows of up to 2,500 ft3/s resulting from a 10-year, 24 hour storm event. This paper provides a synopsis of the project with a focus on the overall design aspects related to siting the tunnel alignment in an urban environment, the hydraulic analyses performed to choose a pressurized system rather than an open channel system, and expected geologic conditions. Tunnel alignment and profile and geological profile are presented, as well as an overview of the construction related impacts considered during design. PROJECT BACKGROUND The proposed Minne Lusa Stormwater (MLSW) Conveyance System will provide for conveyance of separated stormwater from previously completed, and future, LTCP sewer separation projects to the expanded Storz West and Pershing Detention Basins and subsequently, the Missouri River. The project location is representatively shown on Figure 1; the overall conveyance system is represented in Figure 2. The MLSW Conveyance System consists of three separate construction contracts under Contract Numbers: OPW-52004 – The Storz West Detention Basin to 31st & Paxton Tunnel; OPW-52454 – The Storz West/Pershing Detention Basin Grading and Improvements; and, OPW-52752 – The Pershing Detention Basin to ML Outfall Channel. This paper focuses on the project covered under Contract OPW-52004: design and construction of an approximately 6,110 feet 14-foot inside diameter (ID) tunnel, constructed using a Tunnel Boring Machine (TBM). The tunnel will receive flows from the Paxton Boulevard (PB) and the John Creighton Boulevard (JCB) Stormwater Conveyance Sewers and convey the flows to the Storz West Detention Basin, resulting in CSO volume and flow rate reductions to the Minne Lusa Outfall Channel and the North Interceptor."

Jan 1, 2016

By F. D. Wicks

This paper summarizes the direct operating cash costs for the Barrick Mercur open pit gold mine. A comprehensive, detailed system of cost management has been in effect for the life of the Mercur operation. This system provides the basic data for operations control and is the basis for drafting budgets as well as analyzing impact of change on operations costs. The ore body is complex geologically and metallurgically, requiring operators to pay close attention to mining and processing costs. The cost history provides data which enables analysis of changes in production levels, aging of the mine production fleet, and the impact of specific cost changes through time.

Jan 1, 1993

By Norman F. Schulz

The technical excellence of separation achieved in a mineral concentration process, or any other process where two constituents of any kind are physically separated from each other, is expressed uniquely and quantitatively by the Separation Efficiency: ES = (R ? Rg) where R is the percentage of the valuable constituent and Rg the percentage of the waste appearing in the concentrate. The Separation Efficiency meets all the usual requirements of a true efficiency and is independent of the nature of the process used. It can be visualized as the percentage of the feed material that, in effect, actually undergoes complete separation while the rest of the feed is distributed randomly and unchanged into the two separation products.

Jan 1, 1969

By H. Razavizadeh

The recovery of copper from oxide ores containing from 2% to 4.1% acid-soluble copper from the Sarcheshmeh mine in Kerman province of Iran was investigated by agitation leaching in sulfuric acid media. Quartz, as a major constituent, and malachite, as the major copper mineral, were identified in the ore by X-ray diffraction (XRD) and microscopic studies. A series of leaching experiments on the ore was performed over a concentration range of 10 to 20 g/L and temperatures from 15° to 50°C for a maximum of 3 hours. An initial high dissolution of copper was followed by a very slow reaction. By increasing acid concentration and temperature, the dissolution rate of copper was accelerated. However, by increasing acid concentration, the acid consumption of ores was also increased. Surface morphology of solid residues at various leaching times was examined with a scanning electron microscope (SEM). All SEM micrographs of the partially reacted particles displayed a needle structure. The kinetic studies showed that the malachite dissolution rate could be modeled in two stages. About 85% of the malachite dissolution occurred in Stage 1, while the remaining 15% occurred in Stage 2. The data obtained for the leaching kinetics indicate that the dissolution for Stage 1 was a diffusion-controlled reaction with an activation energy of about 20.6 kJ/mole, and the dissolution for the Stag 2 was a chemical-controlled reaction with an activation energy of about 87.6 kJ/mole.

Jan 1, 2008

By K. A. Natarajan, M. R. Sabari Prakasan

"Biodegradation of sodium isopropyl xanthate using two types of bacterial strains, Paenibacillus polymyxa and Pseudomonas putida, is demonstrated. At concentrations higher than 50 mg/L, the presence of xanthate in the growth medium resulted in bacterial toxicity, retarding growth kinetics. Adaptation through serial subculturing in the presence of higher xanthate concentrations resulted in the development of xanthate-tolerant bacterial strains. Stress proteins secreted by bacterial cells grown in the presence of xanthate were isolated. Bacterial cells could utilize xanthate as a growth substrate, degrading xanthate species in the process. Acidic metabolic products generated by bacterial metabolism promoted efficient xanthate decomposition. Probable mechanisms for the biodegradation of isopropyl xanthate are illustrated.IntroductionDifferent types of alkyl xanthates (ethyl, isopropyl, amyl, etc.) have been used as flotation collectors in the concentration of sulfidic ores for several decades. Large quantities of waste water and xanthate-containing effluents are generated by ore flotation processes, posing considerable environmental challenges. Billions of cubic meters of such process waste waters are produced annually across the world, most of which are discharged to the environment, often without any treatment. Leakages and accidental release of xanthate reagents from manufacturing plants and during transportation and storage can also contaminate the environment. Residual concentrations of xanthate reagents are encountered in waste effluent, which are found to be toxic to aquatic life and unfit for human consumption (Harris, 1984; Okibe and Johnson, 2002). Further, direct recycling of such waste waters for plant operations can compromise water quality standards required for process operations. The presence of residual xanthate in recycled waters from flotation plants deleteriously influences flotation processes. Xanthate can be easily decomposed at low pH values; however, CS2, which is more toxic, will be produced by the acidification of neutral and mildly alkaline xanthate-containing solutions. Physico-chemical methods such as flocculation, chemical oxidation and decomposition and physical adsorption used to remove residual collector reagents from mill process waters are often expensive and not environment-friendly (Oliveira and Rubio, 2009; Cheng et al., 2012; Molina et al., 2013,)."

Jan 1, 2015