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By Rainer Kahrger

During the last decade, advances were made in solvent extraction/electrowinning (SX/EW) technologies. Combined with heap leaching, these technologies made it viable to exploit large, low-grade oxide copper deposits. The El Abra Mine is a good example for such a deposit. The deposit is situated in northern Chile at an elevation of about 4,000 m (14,000ft), 70 km (45 miles) north of Calama. Codelco sold 51% of the El Abra to Cyprus Minerals in June 1994, with Codelco retaining the balance. In 1993, Cyprus and the engineer on the project began discussions withinternational companies regarding the materials-handling system requiredfor the project. These early discussions were considered critical for this fast-track project.

Jan 1, 1996

By J. Leinart

As is readily apparent, the reliability of the early-stage costs estimated for any mining project are critical to the viability of that project. An estimate too high might leave a potentially profitable deposit undeveloped or worse yet, available to a competitor. One too low might waste investment dollars in a project not yet economically ripe. There are two aspects critical to any estimate: 1. The cost data used to represent the values of the wages, salaries, supplies, and equipment. 2. The design used to determine the engineering parameters upon which the above estimated values are based. Given that all of the information contained in Mining Cost Service is provided by suppliers, equipment manufacturers and mine operators, one wonders why there is any question as to the reliability of cost estimates developed using this information. Given that it is all actual (as opposed to statistically derived) data, where do the problems with estimate reliability lie and what is the impact of the data on that reliability? The following presents a series of analyses designed to assess the reliability of the cost estimating process. Both the actual cost data and the engineering parameters upon which they are based are examined in an attempt to quantify and understand the importance of each. While several sources of cost information are available (Means, Richardson, Primedia?s Equipment Watch, and individual suppliers and manufacturers), the following rely solely on data contained in InfoMine USA, Inc?s, Mining Cost Service and in its Sherpa Mine Cost Estimating Software.

Feb 27, 2013

By K. Oraee

Rate of penetration of Tunnel Boring Machines (TBM) has a significant role in the planning, measurement of productivity and performance of any tunneling project. In this paper, the application of Adaptive Neuro Fuzzy Inference System (ANFIS) in prediction of TBM penetration rate is evaluated. For this purpose, a database including Rock Quality Designation (RQD), Uni-axial Compressive Strength (UCS) of the rock, the Distance between Planes of Weakness (DPW) in the rock mass, and empirical data regarding rate of penetration of TBM from several tunneling projects are collected. The Rate of Penetration is then estimated by using ANFIS. These results are then compared with measured TBM penetration rates (actual data). It is concluded that ANFIS can be applied successfully for such purpose and result in high accuracy for prediction for the rate of penetration of TBM. The method provided in this paper can assist the mining engineer to estimate the performance of tunneling accurately.

Jan 1, 2012

Explosives are used to mine coal. Any blast results in three size categories of products, namely over-, middle-, and under-size. Boulders can still be broken smaller in further operations after blasting. The under-size, for instance coal fines, negatively affects the mining efficiency. Their reduction ensures better returns. The paper concerns investigations aimed at reducing coal fines' generation. Inherent fractures are identified as one of source of fines. The discussion is therefore centered on establishing a relationship between the fracture occurrence, the explosive properties and the blast outputs evaluated in terms of the fines generated.

Jan 1, 1996

By Kumara S. Rachamalla

Long-term stability, appropriate taxation and incentive policies are essential to attract and stimulate investment in the mineral sector. An outline of Ontario's $4.6 billion industry and associated tax incentives is presented. Producers are offered incentives under The Mining Tax Act, federal and provincial income tax acts for exploration and development by reducing Me after tax cost to 13-25¢ for each dollar spent. The Mining Tax Act provides generous processing incentives which have positive effects in enhancing investment and economic advantages of building processing facilities. Non-mining companies and entrepreneurial individuals can receive 25% of eligible exploration expenditures in grants/tax credits under the Ontario Mineral Exploration Program.

Jan 1, 1982

By P. Mills

More than 95 percent of all the barite mined and produced is used in the petroleum industry as “drillers mud.” The remaining barite is used in the industrial and medical markets. Therefore, the amount of drilling activity is a good indicator of the health and growth of the barite industry. The four major barite-producing countries in the world are China, the United States, India and Morocco. In 2005, the average number of drilling rigs exploring for oil and gas increased by about 15 percent over the average number in 2004. This increase in oil and gas exploration has resulted in a higher demand for barite and an increase in barite production.

Jan 1, 2006

By A. Güngör, Ü. Atalay

Thermal treatment can significantly improve industrial comminution operations by reducing energy requirements and increasing mineral liberation. The assistance of thermal pretreatment prior to grinding by microwave heating is scrutinized in this study. For this purpose three copper ore samples with different chemical composition were used. To see the effect of microwave heating on ore; work index, breakage rate and breakage distribution functions of original and heat treated samples were examined. The results obtained in this study did not show significant improvement in the grindability characteristics of the studied ores with microwave heat treatment. The inadequate amount of microwave transparent matrix was the main reason for the absence of cracks and micro-fractures in the microwave heated copper samples.

Jan 1, 1999

By F. Habashi

Brazil is a major mineral and metal producer, has magnificent fauna and flora, and superb architecture. In 1693 gold was discovered in Ouro Preto and Brazil produced about half of the world's gold. In 1726 diamond was discovered in the region of Tijuco in the Province of Minas Gerais, 150 km east of Bello Horizonte. The country became independence from Portugal in 1822 as the Brazilian Empire. In 1876, an Englishman succeeded in obtaining from the Amazon region seeds of rubber trees and secretly transferred them to England, where they were planted in the royal gardens at Kew. Some of the seedlings which spouted were sent to Ceylon and Singapore. Thus, began the rubber industry in the East. Today, Brazil is the largest producer of niobium, and produces a large number of other metals. The Mineral Research Center in Rio de Janeiro is the countries main Government establishment for mineral research. The country has been a republic since 1889 with its capital in Brazilia.

Jan 1, 2009

By John Reilly

Traditional methods of project procurement of have remained virtually unchanged in the U.S. infrastructure construction industry for more than 50 years. The traditional method, Design-Bid-Build (DBB), uses a two-step process that separates planning and design from construction. Design is generally done by the public agency and their consultants and the subsequent construction contract is procured from the private sector, almost always by a “low-bid” approach. This method has worked well for many projects, delivering quality work for the lowest bid price. This is particularly true for those projects where the work, and the public agency’s management procedures, are well understood by the contracting community and there is relatively low uncertainty in the work or conditions, particularly geotechnical conditions for underground construction. However, concerns exist with the DBB process. It is time consuming because all planning and design work must be completed prior to beginning any construction work and it is of concern for complex or large projects, plus those with significant risk, where the separation of design and construction, in conjunction with pressures resulting from the low-bid environment, often result in substantial cost and schedule increases. Frequently, these increases occur in a non-productive, inefficient, adversarial work environment leading to claims, disputes and costly litigation (Quick 2002).

Jan 1, 2007

By Yoginder P. Chugh

Most mines are large producing 0-25 mmt annually. The coal is mine.) at depths ranging from .0-150 m 120-500 ft mining at 300 m .(,1000 ft) depth is anticipated in the future. Single and multiple seams ranging from 3-12 m 10-40 ft) in thickness are mined. Most overburden is unconsolidated and consists of sands, and sandy or silty clays. The stripping ratio (volume of overburden to volume of coal mined) varies from 3-L. The overburden and coal is mined in benches 8-12 m -(24-40ft) high; the high-wall angle is about 45 degrees. Bucket wheel and bucket chain excavators are commonly utilized for overburden and coal removal, Some of the large overburden stripping machines nave capacities. Ranging from 4400-10,000 bank cu ( 6000-14,000 BC) per hour. The overburden from the upper benches is transported around the pit using the trains and belt conveyors. It is deposited in the spoils using large stacker-conveyor systems capable of handling 2550-7300 cu m/hour (7500-10,000 cu yds/hour). The overburden from the bottom two or three benches is transported across the pit using the conveyor bridges which are computer controlled. Conveyor bridges capable of handling overburden up to 60 m (200 ft) high are currently in use; a 60 a (20e ft) high conveyor bridge has a capacity of 85 x 10 cu ( 118 x 10 cu yd) annually. The coal is loaded in the trains directly and shipped to power plants or coke oven plants.

Jan 1, 1980

ME?s Arizona Conference was held at the Hilton El Conquistador resort in Tucson on Dec. 2 and 3, 2007. The annual conference is organized by the Arizona Conference Board of Directors, which represents SME sections in Arizona and adjacent areas. The conference provides an opportunity for individuals and corporations associated with mining in the region to get together once each year to discuss the status of the industry. The 2007 meeting featured a keynote address, a distinguished lecturer and more than 25 technical papers that were presented in seven sessions. The sessions included environmental, geology, safety, metallurgy, mining, new projects and a special session on Mexico. Topics covered included mine closure, sustainable mining, exploration methods, health and safety issues, mining equipment and drilling. Much of the discussion at the conference concerned major new developments in the region?s copper mining industry. For example, Freeport-McMoRan?s new Safford Mine and BHP Billiton?s Pinto Valley restart were the topics of technical presentations. There was also much discussion among the attendees on the current and future price of copper, community relations, education issues and recruitment concerns. At the time of the conference, the price of copper hovered around $3.30/lb, up considerably from the 61 cents/lb in late 2001, when the industry was being challenged by world market conditions and a weakened domestic economy. Since then, strong demand from China helped push copper prices to record levels that at one time reached as high as $4/lb. The general consensus among the attendees is that the current price of around $3.30/lb will continue through 2008. Most attendees also expect increased corporate investments in the industry to continue. Copper mining in Arizona has been a major industry since the 1800s. In 2007, Arizona was the leading copper-producing state in the United States and produced more than $5 billion worth of copper. The copper mining industry in Arizona also produces byproduct gold, silver and molybdenum. Arizona is the second largest molybdenum producer in the United States.

Jan 1, 2008

By N. K. Mendiratta

Diethylenetriamine (DETA) is known to be an effective pyrrhotite depressant in pentlandite flotation. It has been reported recently that its performance becomes more consistent when the reagent is used in conjunction with sulfur dioxide (SO2). In the present investigation, the effects of DETA and SO32- ions on the changes in the hydrophobicity of pyrrhotite electrode have been studied at pH 6.8. The results show that both DETA and SO32- can reduce the water contact angles of pyrrhotite; however, the contact angles can be reduced to zero only in the presence of the SO32- ions. This finding may be attributed to the ability of the SO32- ions to reduce the polysulfides formed on pyrrhotite by superficial oxidation, which may in turn provides an explanation for the robust performance of DETA/SO2 combination.

Jan 1, 2001

By R. B. Massy-Greene

Project engineering and development is a process of optimisation of capital, operating and financial costs, and extraction rates in the light of current and forecast economic conditions for the sale of the product. The aim of the process is to maximize financial returns to the sponsors (project owners) within many often conflicting constraints. Thus, the sponsor's engineering and financial staff have a common goal, with performance measured in financial terms. Consequently, each group must be aware of, and responsive to, the constraints imposed upon the other. For financial staff, the increasing size and complexity, and escalating capital costs of new ventures have required them to seek finance in larger amounts, and by non-traditional methods. In addition, senior management are requiring indications of the availability of finance as a pre-requisite to a decision to commence project development activities.

Jan 1, 1982

By T. Pool

Introduction After two decades of contraction and consolidation, the uranium industry has seen a recent major expansion. Rapidly increasing uranium prices and the ability to raise speculative capital in share markets worldwide have brought over 300 new participant companies into the uranium industry: “juniors” as they are known. These companies participated in a global land rush for known deposits as well as for prospective land positions in order to secure a “piece of the action” for their respective portfolios. Mostly publicly-traded companies, these “juniors” have captured the attention of world’s investing public with spectacular gains; as much as 1,000s of percent in less than four years. The initial phase is over, however, and these companies must now prove that they can be successful in exploration or production.

Jan 1, 2007

By J. H. Kempton

Refinement of environmental procedures can produce significant cost savings at most mines. Grouting permeable aquifers reduces water pumping and disposal costs. Stable groundwater quality supports reduced groundwater monitoring; and for contaminated groundwater, in-situ or natural restoration should be evaluated. Waste-rock characterization can be minimized using fewer (but more representative) samples, inexpensive surrogate analyses (e.g., NAG instead of humidity cells), and appropriate tests (e.g., avoid meteoric tests on sulfide). Selective waste-rock handling should be compared to random emplacement, which is often cheaper and more stable. Finally, incorporating schedule uncertainty in modeling allows the flexibility to revise mine plans within permits.

Jan 1, 2000

By A. D. Davis, C. J. Webb, C. S. Johnson, J. L. Porter

The abandoned Belle Eldridge Mine near Deadwood, South Dakota, is on land controlled by the U.S. Bureau of Land Management (BLM) property. The mine produced primarily lead and zinc during the first half of the twentieth century. The BLM has expressed concern about acidic drainage as well as elevated arsenic levels in tailings and waste rock at the site. The mine site was evaluated for remediation in 1998 and 1999. Recent reclamation and remediation work included substantial regrading of waste rock, removal of material where metal loading were of concern, and re-routing of drainage from an adit. Trenching at the site shoed a greater volume than originally calculated during site characterization. Material was removed to a repository that was constructed at a nearby drainage divide. Because of physical hazards, the BLM has decided to remove some historic structures. However, a search of mine records and an inventory of archival materials were complete to preserve the history of the site.

Jan 1, 2002

By K. A. Lapakko, D. A. Antonson

Fourteen samples of pyrite-bearing Archean greenstone rock (d < 6.35 mm, 0.04% < St < 1.22%) were characterized (particle size, chemistry, mineralogy) and subjected to laboratory dissolution testing. The only sulfide and carbonate minerals identified were pyrite and siderite, respectively. Quartz, chlorite and sericite typically comprised 90 to 98 percent of the mineral content. For the first 60 weeks, seven samples with sulfur contents less than or equal to 0.16% produced drainage pH values exceeding 6.0. Over this period, six of the seven samples with sulfur contents greater than or equal to 0.20% produced drainage pH below 6.0, with minimum values ranging from 3.2 to 4.7. The seventh sample (0.72% S) had a siderite content of 18%. Small amounts of magnesium and, to a lesser degree, calcium carbonates present in the siderite apparently dissolved to neutralize acid and maintain drainage pH above 6.0. Sulfate release rates generally increased as sulfur content increased, and the rates of pyrite oxidation estimated for individual samples were roughly half to five times that reported in the literature for the abiotic oxidation of pyrite by oxygen. Observed neutralization potentials ranged from 0.2 to 2.0 g CaCO3/g rock.

Jan 1, 2002

By H. Kinilakodi

The authors previously had developed a methodology that combines injury and citation measures into an overall mine safety performance evaluation tool, called the Safe Performance Index (SPI). It can be easily adopted by mine operators to monitor trends in their injury and citation experiences as a risk assessment method. In this paper, six normalized safety measures and the SPI are used to evaluate the risk that existed at mines in the two years preceding the occurrence of a fatality. The percentage of mines is given for which the risk was high or where trends of some of the safety measures indicated moderate risk. In 50% of the mines, this mine safety performance tracking method could have been helpful to the companies, state agency, or MSHA in recognizing and addressing emerging problems with actions that may have been able to prevent high-risk conditions, the fatality, and/or other serious injuries. The approach would have given scrutiny to the risk for mines that encompassed 74% of the fatalities during 2007-2010.

Jan 1, 2012

Recent U.S. mine disasters identified a need for improved training of miners in escape from mine fires and explosions. Researchers at the National Institute for Occupational Safety and Health?s (NIOSH) Spokane Research Laboratory (SRL) have designed fire-escape training software for use in a mine-safety training course. The software allows four trainees to work together in a virtual world via a computer network. Trainees responded favorably and showed a marked improvement in locating the proper evacuation routes on subsequent trials. In collaboration with the Pittsburgh Research Laboratory (PRL), a more elaborate fire evacuation scenario is being developed. Further study is needed to confirm that virtual training will translate to improved safety outcomes in the real world. Keywords: virtual reality (VR), safety, training, mining, mine fire evacuation

Jan 1, 2009

By D. J. Carpenter

Safe and successful mine closure represents a fundamental work element that needs to accommodate the geochemical conditions existing at the completion of the mining and ore processing effort. Given the interests in limiting costs and time associated with mine closure efforts enhanced prior understanding of the geochemical conditions likely to exist upon exhaustion of the economic reserves can provide important benefits. The purpose of this paper is to document the benefits associated with geochemical modeling and understanding how the ore formation process may impact mine closure efforts, using one ore deposit type as an example. Specifically, this paper will emphasize the geochemical processes leading to the formation of sandstone-hosted uranium roll-type deposits and how the resultant concentrations and distributions of ore and gangue phases need to be incorporated into understanding the geochemical conditions projected to exist at the end of mineral recovery efforts. The paper will describe the evolution of geochemical conditions leading to ore body formation and the geochemical effects induced by open pit mining and how these may be used to understand both the geochemical controls and constraints on residual mine water. In addition, a discussion will be provided on how these conditions may be simulated by solution equilibria and kinetic modeling to develop optimum approaches to achieve applicable closure standards. This paper will also discuss specific augmentations to existing industry standard solution equilibria and kinetic models and associated thermodynamic databases to maximize the predictive accuracy of the geochemical modeling results. The benefits of understanding the electrochemically reactive behavior of uranium and associated gangue phases and incorporating this behavior into mine closure efforts will be presented. The culmination of the benefits of the geochemical modeling will ultimately be the development of a sustainable approach to uranium mine closure that is based upon an engineered environment designed to return the ore body to stable geochemical conditions.

Feb 27, 2013