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By K. Whiting, R. Huffsmith, R. Olsen, D. Adams

Long-term closure alternative selection for heap leach pad effluent is a daunting task. Passive water treatment, if designed with enough long-term capacity, can minimize long term O&M while meeting water quality objectives. Leach pad effluent from a 30-acre leach pad at Basin Creek Mine, Basin, Montana was targeted for long-term water treatment using a passive water treatment system. The objectives and results of design and construction are: 1. Design a long-term passive system utilizing existing infrastructure. 2. Construct a field scale pilot test at the mine site.

Jan 1, 2002

By John Reilly

Costs of complex/underground projects have been consistently underestimated and delivery on time and on budget has been problematic. This has been attributed, to inadequate cost estimates and unidentified and/or insufficiently managed risk. Use of probabilistic cost estimates like the Washington State Department of Transportation?s CEVP® process (developed by the author and others) has produced more realistic cost estimates, explicitly identified and quantified risk (as input to risk management plans) and early awareness of key project issues. This paper updates previous work (NAT 2004), adds implementation detail for probalistic cost estimating as used by WSDOT, FHWA and other agencies and will address key issues in risk management, as related to probalistic cost estimates.

Jan 1, 2008

By D. Brunner, G. R. Baiden, H. J. Yazici

System simulation is an increasingly popular technique for analyzing and improving existing as well as newly designed underground mining operations. An engineering firm that specializes in simulation helped a major metals producer build a long-range planning model of an existing underground mine. Subsequently the team adapted this model to assess technology alternatives in the design of a new mine. The two models differ in the level of detail used for modeling the development process. This paper discusses the differences in approach between the models along with the experiences gained and challenges faced during the construction and use of the models.

Jan 1, 1999

By E. Arioglu

Discussion by E. Arioglu Y. Luo and S.S. Peng are to be congratulated for their outstanding paper providing new results from surface subsidence monitoring over longwall panels under different conditions. This writer found the authors' paper very interesting. In reference to this paper, the following contributions are offered: • In the paper, the maximum possible subsidence [(ASmax)] induced by chain pillar convergence has been related to a parameter (h/1- p) by linear regression. (Notations are expressed in this discussion's Fig. 1 (b).) It is a well-known fact that in a goaf the roof lowers onto broken material that gradually compacts. Then the physical behavior of goat may closely follow the compaction characteristics of broken materials. In light of this assumption, a mathematical means (Fig. 1(a)) of defining the expected compaction (i.e. surface subsidence) represents an exponential expression between [ASmax/m vs. h/1-p]. This is based on Luo and Peng's field observations from the Appalachian, Illinois and Alabama coal fields. (The coefficient of regression "r" under consideration was computed to be 0.883). • According to Wardell's (1969) findings for board and pillar mining, the maximum possible subsidence can be expressed in terms of maximum pillar loading (depth, ratio of extraction) and the height-to-width ratio of the pillars left. Using Luo and Peng's 1991 results, this writer discovered a regression equation between the above-mentioned factors. As displayed in Fig. 1(b), the functional expression approximates as closely as possible the observed subsidence data. It may be noted here that Wardell's approach (1969) can be successfully utilized for longwall panels having chain pillars. Reference Wardell, K., 1969, "Ground surface and control," Mining Congress Journal, January, pp. 1-7.

Jan 1, 1993

By M. E. Smith

Waste rock dumps, tailings impoundments and spent leach heaps are common features at mine sites. Many of these waste disposal facilities contain sulfide-rich minerals, which generate acid mine drainage (AMD) when they oxidize. Control of AMD can be achieved by removing one or more of the three essential components in the acid-generating process (sulfides, air, or water). One AMD prevention measure is to cap the waste with an engineered cover system to minimize the infiltration of water and diffusion of air into the system. Possible cover designs include: ? Earthen ?store-and-release? covers (also known as evapotranspiration (ET) or water balance covers), including capillary barriers. These covers require climate conditions where there is both modest to little rainfall and significantly greater evapotranspiration than precipitation, both annually and seasonally. ? Low-permeability compacted clay liners (CCLs) employing fine-grained soils typically compacted at wet of optimum water content. ? Geosynthetic composite covers, comprised of a geomembrane liner placed over and in direct contact with either a CCL or a geosynthetic clay liner (GCL). These systems have been commonly used for base liners for leach pads as well as covers and base liners at municipal solid waste (MSW) landfills in the US for more than 20 years. Comparisons of these different cover systems, both in terms of performance and cost, are presented later in this paper. First, however, a review of the typical mine closure approaches, and the possible rationale behind them, is warranted.

Feb 27, 2013

By P. van der Veen

The objective of this paper is to analyze the evolution of the strategic drivers of the mining sec-tor over the last half century, which has been guided by a varying and expanding list of motivations. While companies cannot survive for long unless they are making profits, the strategic drivers of the industry have gone far beyond profits since at least the mid-1970s when environmental concerns began to be taken seriously. For the most part, these forces have followed global trends and public opinion, but they have been shaped and magnified by the significant, often dominant role that the mining sector plays in many economies. While the mining sector used to be primarily motivated by the first pillar of sustainable development -i.e. the economics pillar-, in the 1970s the second environmental pillar became an important factor in decision making, and in the 1990s the third social pillar emerged as a major driver.1 The entrance of new strategic drivers has also had considerable impact on technological and organizational developments in the mining industry; however, technological changes, driven by cost reduction considerations, have in turn impacted the strategic drivers of the industry, resulting in the need for further technological and organizational developments.

Jan 1, 2007

By D. K. Denton, M. J. Friedel, D. F. Scott, T. J. Williams

Spokane Research Center personnel have been investigating the use of seismic tomography to monitor the behavior of a rock mass, detect hazardous ground conditions, and assess the mechanical integrity of a rock mass affected by mining. Seismic tomography can be a valuable tool for determining relative stress in deep ( > 1220 m) underground pillars. If high-stress areas are detected, they can be destressed prior to development or avoided. High-stress areas can be monitored with successive seismic surveys to determine if stress decreases to a level where development can be initiated safely. There are several benefits to using seismic tomography to identify high stress in deep underground pillars. The technique is reliable, cost-effective, efficient, and non-invasive. Also, investigators can monitor large rock masses, as well as monitor pillars during the mining cycle. By identifying areas of high stress, engineers will be able to assure that miners are working in a safer environment.

Feb 24, 1997

By O. MacIntosh

The Round Mountain gold mine, located 90 km (55 miles) north of Tonopah, NV began large-scale production in 1977. During 2008 Round Mountain Gold Corp. (RMGC) relocated the primary crusher facility approximately 300 m (1,000 ft) to make room for the next phase of openpit mining activities. This facility was installed in 1988 and used a log-crib retaining wall and dump pocket. RMGC selected Hilfiker Retaining Walls and Collins Engineers, Inc. to provide design and materials for a new 17-m- (56-ft-) high mechanically-stabilized embankment (MSE) wall to support the haul trucks at the new location. The construction contractor was EarthTech West Ltd. of Norwood, CO. An MSE wall with a cast-in-place concrete face was chosen as a durable, yet less expensive alternative to the reinforced concrete dump pocket that was originally designed for the project. The arrangement of the MSE wall is of an unusual configuration to meet a variety of operational and maintenance requirements. This paper outlines the selection process, design and construction of the MSE wall.

Jan 1, 2010

By S. K. Kawatra, S. J. Ripke

Bentonite clay is used as a binder for iron ore concentrate pelletization. Bentonites are sensitive to cations such as calcium, magnesium, sodium, and potassium that are known to be dissolved in the moisture remaining in the iron ore concentrate. These cations affect the ability of bentonite to absorb water, as measured by the plate water absorbance (PWA) test. This paper addresses the relationships between plant water chemistry and pellet strength for a wide PWA range of bentonites. Experiments were conducted to determine the effect of concentrate moisture solute chemistry and bentonite PWA value on the wet knock and wet and dry compressive strengths of iron ore pellets. Experiments used seven different types of bentonite that had PWA values ranging from 564 to 1033. Flushing plant concentrate with distilled water to remove the dissolved cations resulted in increased pellet strengths, to a widely varying degree, for each bentonite tested; wet knock values increased an average of 92% and dry compressive strength increased an average of 46%. In addition, pellet strengths were not found to be directly related to the ability of bentonite to absorb distilled water, measured by the PWA test.

Jan 1, 2002

By D. Campos, J. M. Macedo, S. Chadwick

The incorporation of low cost technology transfer to increase the ability of locals to acquire and maintain long term employment are key ingredients for sustainable industrial development. Alcoa’s Alumar plant on the island of Sao Luis is the largest and most modern refinery/smelter complexes in northern Brazil. The plant has one of the most advanced Environmental, Health, and Safety management process in the aluminum industry. Technical assistance, training and financial support were made available to Alumar to address social sustainability issues. Through several programs led by employees on a voluntary basis and applying intensive and extensive training programs, Alumar has enabled local people to develop skills on agriculture and land management, wastes minimization, small business development and administration, all based on sustainable development and social responsibility concepts.

Jan 1, 2004

By James A. Pendleton

In response to Public Law 95-87 (SMCRA), Colorado promulgated regulations governing the mining of Coal. These regulations require the prediction, monitoring and mitigation of "material damage" caused by subsidence. All permitted underground coal mines within Colorado have approved subsidence programs. Preliminary monitoring results indicate the subsidence mechanical predictions have been sufficiently accurate to preclude material subsidence damage. The State of Colorado has developed a practical approach to regulating subsidence, which stresses monitoring verification of predicted subsidence phenomena. However, shortcomings exist in our ability to precisely predict the secondary consequences of subsidence, including effects to structures, the hydrologic balance and the environment. Lack of accuracy in predicting these secondary consequences results in uncertainty, necessitating conservatism in permitting. To avoid increasingly stringent permit restrictions, future research should emphasize the secondary consequences of subsidence.

Jan 1, 1986

By H. Gerry Stephenson, Devin Castendyk

"One of the most important environmental issues associated with contemporary openpit mining is the closure of mine pit lakes, and the perpetual legacy these lakes can potentially generate. Ideally, successful pit lake closure includes the following:• The water quality within the pit lake, plus surface water and ground water discharging from the pit lake, meets premining or other acceptable water quality conditions of the receiving environment. • The termination of all active treatment processes.• The return of the pit lake to the government for long-term care and maintenance.• The release of the mining company from all future liabilities associated with the pit lake.• The return of the environmental bond to the mining company.• The reuse of the pit lake for some post-closure, beneficial purpose.The achievement of these goals is known as walk away pit lake closure.Peer-reviewed publications of successful walk away, pit lake closure provide mining companies with the ability to address public concerns regarding the safety of pit lakes which commonly occur during the permitting, operations, and closure phases of mining. To date, most published work on walk away, pit lake closure work has occurred in the coal mining sector in Germany and Australia (McCullough et al., 2009; Jones and McCullough, 2011; Kumar et al., 2013; Schultz et al., 2013). In North America, examples of walk away, pit lake closure are not widely discussed in the literature despite there being excellent examples from the coal mining sector in Alberta, Canada (e.g. Pleasure Island, Black Diamond, East Pit, Sphynx, Robb, Lovette, Siltstone and Sterling), and from the iron mining sector in Minnesota in the United States (e.g. Portsmouth Lake, see MNDNR, 2018). Although seldom included in discussions of pit lakes from the metal and coal mining sectors, the aggregate and fabricated-stone mining sectors also produce pit lakes, and there are numerous examples throughout North America where these pit lakes have been successfully closed and transformed into post-mining resources (Vandenberg, 2018; Crossman, 2019). The difficulty of finding these good examples in the literature makes it challenging for companies to respond to public and regulatory questions regarding pit lake closure and reuse. As such, there is a pressing need to document the motivations and approaches used in examples of successful, walk away, pit lake closure in North America so that the mining industry, at large, can learn from these examples and can better address public concerns."

Aug 1, 2019

By H. Lyn Bourne

This is the seventh annual tabulation of royalty information. It is also the first year in which some data have been deleted to make room for new data. The concept of royalties evolved from a time when the government owned all of the land, including mines, to the situation where free miners won the right to claim minerals but paid a portion of their production to the royal treasury. Today, a mineral royalty is a payment to the owner of the mineral rights for the privilege of producing the mineral commodity. However, some people incorrectly believe that the selling price and the royalty are the same thing. The contract between the owner (lessor) and the mining company (lessee) is the mineral lease. Some clauses that are common to mineral leases include: identification of property, granting clause, reservations, definitions, royalty rate, taxes and title, indemnity, termination, inspection, assignability, successors, and reclamation. There often are variations in royalty rates for a given commodity that reflect differences in location, quality, market conditions or public versus private ownership. History In the time of ancient Rome, the government owned the mining properties by virtue of conquest. It would lease the mines to favored citizens who would pay rent to the State. Various conditions of sovereign ownership of both land and mineral rights continued in Europe until the Renaissance. As the laws evolved for land ownership by private citizens, the concept that minerals belonged to the State (King, Crown, sovereign) continued until about the 15th century. Free miners challenged the notion of sovereign ownership and won the right to discover and claim minerals. But a portion of their production had to be paid to the sovereign - a royalty. So, the original concept of a mineral royalty was a tax on production that was due to the Crown or Church. The term mineral royalty, as it is known today, is a payment to the owner of the mineral rights (formerly the royal owner) for the privilege of mining and producing the mineral commodity. The owner of the mineral rights, the lessor, and the mine operator, the lessee, enter into an agreement to mine the property. The agreement is the lease. While this concept is common, there are some who do not understand that the royalty is a portion of production paid to the owner as agreed on in the lease document. This author has seen reports where the selling price of a commodity has been quoted as the royalty. ("They get 70 cents a ton royalty at their pit and the guy down the road only has a 65 cent royalty.") These reports have been authored by people not familiar with the mining industry. Lease clauses In addition to the amount to be paid the lessor, there are several other items to be addressed in the lease agreement. The following list may not be all inclusive, but briefly describes most of the common clauses any good mining lease should contain. Identification: This opening clause names the owner (lessor) and the operator (lessee), the address of each, and gives the legal description of the property. Granting clause: This part of the lease gives the time period or duration of the agreement and information about renewal periods. It also has language about the exclusive right of the lessee to mine the property. Reservations: If the owner wants to exclude any portion of the property or set some specific conditions about the operation, there needs to be a clause that describes these reservations. Definitions: This section should address some of the technical terms that the lessor may find confusing - short tons versus cubic yards, dollars versus percentage of average selling price, any escalator indices such as consumer price index or producer price index, and material mined versus material sold. Royalty: This section spells out what the royalty rate will be, how often it will be paid, if there is an annual minimum, the pay dates, and how the records will be kept. This section also describes the conditions under which the lessee is exempt from the annual minimum - natural disasters, strikes, governmental actions, or other causes referred to as force majeure. Taxes and title: The lease needs to identify who is responsible for the property taxes, severance taxes (if applicable), and other taxes that relate to the mining activity - taxes on equipment, improvements, or stockpiles. This is a good place in the lease for the owner to certify his ownership of the property and its mineral rights and also certify that no other leases are in effect. The lessees may want language that allows them to pay mortgages or other debts on the property to keep their lease in effect. Indemnity: This portion of the lease identifies that the lessee assumes the risks for lessee's mining operation. Lessor should expect indemnification by the lessee through standard insur¬ance policies - workers compensation, liability and property damage. Termination: Both the lessor and lessee want language that will allow them to terminate the lease. This section of the lease describes the conditions under which one of the parties may terminate the lease (failure of the

Jan 1, 1989

By G. C. Hall, B. E. Hobbs

Giant gold deposits are considered products of crustal-scale systems. Reduced fluids stored in mid to lower crustal reservoirs were discharged into mid to upper crustal sites of deposition. Elements of the architecture include crustal-scale structures, reduced packages of rock and regional seals. Gas-rich aqueous fluids were common but non-aqueous fluids may have been significant in the deeper parts of the systems. Fluid fluxes in over pressured domains were maintained by porosity waves. Abnormal heat input from the mantle may not be required once the systems were perturbed. Fluid-mixing and hypogene enrichment were probably the most significant precipitation processes.

Jan 1, 1999

Simulator technology has advanced to the point where the cost of mining equipment simulators is beginning to make commercial sense. Simulator-based evaluation allows operators or potential employees to be assessed in a pseudo-real environment under surface and underground mining conditions. Simulator training also allows operators to be exposed to emergency and advanced situations such as brake or steering failure or a tireblowout. ThoroughTec, of South Africa, provides simulator equipment to the mining industry. The company’s various packages of simulator products provide an unbiased evaluation score that removes human error from the assessment process. This same evaluation score is also presented at the end of normal training or refresher training sessions. In this way, the simulator helps eliminate bad habits and improve efficiencies.

Jan 1, 2003

By J. V. Ghelarducci, M. A. Sharpe, D. G. Chedgy

This article presents a novel design, called the Climax, High Capacity Processor (HCP), for pre-combustion cleaning of coal. This design is particularly suitable for the plant capacities of 400 ~ 660 TPH. The HCP is different from the conventional designs with an equivalent throughput in three major aspects: 1) the use of one large capacity HM cyclone to separate coarse and intermediate raw coal in a single circuit; 2) the elimination of the conventional secondary magnetics recovery system by use of the high efficiency Climax, magnetic separators; 3) the use of "single line" piping with a minimum requirement of ancillary devices. In comparison with conventional designs with similar capacity, the HCP plant costs much less in capital investment, operation and maintenance.

Feb 24, 1997

By H. I. Kim

The leaching of a complex matte in chlorine and chloride media was studied. The matte was prepared from manganese nodules by the reduction smelting-sulfidation route. From XRD analysis, the major phases of the matte were identified as CuFeS2, CuS2, (FeNi)9S8, (FeNi)S2, Ni9S8, Ni3S2, (CoFeNi)9S8 and Co metal. Investigated were the chlorine, hydrochloric acid, hydrochloric acid-oxygen, ferric chloride, ferric chloride-oxygen, cupric chloride and cupric chloride-oxygen systems. The results are discussed in terms of reagent concentration, retention time, leach temperature and gas sparging rate. The chlorination process resulted >99% metal extraction efficiency within a short retention time and at atmospheric temperature. However, there were no preferential extractions of Cu, Ni and Co with respect to Fe. The cupric chloride-oxygen system produced leach liquors with the lowest Fe content and with a high base-metal extraction. Sulfide sulfur was converted to mixtures of elemental sulfur and sulfate in all the studied systems.

Jan 1, 2009

By D. C. Hogeman

Growing Greener is the single largest investment of state funds in Pennsylvania’s history, allocated to address the Commonwealth’s critical environmental concerns. Signed into law by Governor Tom Ridge on December 15, 1999, Growing Greener will enable the Department of Environmental Protection (DEP) to appropriate nearly $240 million over five years, to watershed restoration and protection, abandoned mine reclamation, and oil and gas well plugging projects. DEP has utilized these allocations in some remarkably innovative ways, as it: involves the cooperation of several state agencies, local governments, and grassroots organizations to address environmental concerns of the Commonwealth, provides funds directly to watershed groups based on locally determined decisions for local watersheds and offers a user friendly process. In three years, over $130 million in watershed restoration and improvement projects have been initiated.

Jan 1, 2002

The Pogo Mine, near Delta Junction, Alaska is a new 2500 STPD gold operation. The control system of the mine and milling operations are a hybrid of DCS (Distributed Control System) control and PLC (Programming Logic Controller) control. A DeltaV DCS system serves as the main control and operation platform while the PLCs operate a multitude of vendor specific packages. The communication backbone of the DCS system is a hybrid of star and ring fiber optic topology, which provides reliability and flexibility. The communication between the DCS and PLCs is typically facilitated by serial communication. This communication insures the integrity of the whole control system.

Jan 1, 2008

By M. D. Johnson

Mina Santa Rosa, in west central Panama, is the first large-scale gold mine in Panama and will soon be the largest single-mine gold producer in central America (Fig. 1). At full production, the mine will process 1.8 Mt/a (2 million stpy) of ore and produce more than 1.8 t/a (60,000 oz/year) of gold and 9.3 t/a(300,000 oz/year) of silver. Mina Santa Rosa is a subsidiary of Greenstone Resources of Toronto, Ontario. Freeport-McMoRan geologists first visited the area in 1985. Their rock chip sampling adjacent to old shafts and adits confirmed widespread gold and trace element geochemistry anomalies. Surface mineralization appeared to be localized in and adjacent to narrow veinlets. However, they recognized astructural setting similar to the Nevada Tertiary volcanic-hosted epithermal gold systems.

Jan 1, 1996