Search Documents

By Eiji Kojima

In this research, dynamic and static load tests were performed on permanent foundation piles which had a pile length of 30 m, 800 mm in outer diameter and 15 mm in wall thickness. In this site the dynamic horizontal load test on a smaller test pile, 12 m in length, 500 mm in outer diameter and 12 mm in wall thickness, was also carried out. The static horizontal load versus horizontal displacement derived from the dynamic load test conformed well to that measured in the conventional static horizontal load test of the pile with 800 mm diameter. Then an attempt was made to predict the horizontal load displacement of the pile with 800 mm diameter based on the results of the dynamic horizontal load test of the pile with smaller diameter of 500 mm.

Jan 1, 2006

By M. Cornelius

Drilled shaft construction through caving soils has historically been an uncertain, risky and costly operation. Uncertain, because the zone of caving may or may not be known, risky because the loss of a shaft is disastrous, and costly because the Contractor, who faces these risks, must include large sums of money in his bid for shaft wall stabilization techniques. This case study will discuss the stabilization techniques that are typically used within the United States, and then present new technologies, born in Europe, that are being utilized in the States by Malcolm Drilling Company today.

Jan 1, 1999

By E. Stiakakis

The paper presents a geotechnical simulation of the "Mavropigi" open pit mine (Western Macedonia Lignite Center, Greece), using the finite element method. The simulation was based on the initial planning of the pit using Mohr-Coulomb and Soil Hardening models. Results indicate high stability factors as well as the magnitude of the expected horizontal displacements and floor heaving. However, these deformations do not influence decisively the overall stability unless locally adverse tectonics are encountered. Results can be used in the ongoing update of mine planning and stability evaluation.

Jan 1, 2006

By F. Lombard

We consider the Grubbs estimation of the precision of an online gauge. Typically, this type of estimation involves independent results from two or more reference instruments (sampling and laboratory analysis operations). The properties of the estimator are then independent of the product variability. However, the use of more than one reference instrument entails significant additional costs. The two-instrument Grubbs estimator, which is based on results from a gauge and a single reference instrument, has the disadvantage that its standard error is heavily dependent on the degree of product variability. We propose a new estimator that has a variance that is more or less independent of product variability. In fact, the variance is typically less than that of the Grubbs estimator based on the use of two reference instruments. In order to function successfully, our methodology requires some prior knowledge of the extent of product variability and of gauge precision. In practice, such prior knowledge is often available and it is a weakness of the traditional two - and three-instrument Grubbs methods that no use is made of such knowledge. The efficacy and robustness of the new method is illustrated by Monte Carlo simulation.

Jan 1, 2012

By Richard Poulin

Rehabilitation of mined out areas is often enforced by environmental bonding. It is usually assumed that this process provides financial assurance that rehabilitation will be carried out as agreed at the permitting stage. Shortcomings of the current practice in environmental bonding for mining are reviewed. Of particular importance for the public, for governments and for the environment is the absence of protection against cost overruns and companies defaulting before the bond amount is entirely paid. Elements of solution are identified through the emergence of environmental insurance as a complement to bonding for cost overruns and defaults. A cover of environmental catastrophes could also be added, hence reducing the risk for the public and the environment. We examine the merit of creating a captive insurance company under the responsibility of the mining industry. The use of insurance techniques would incorporate a genuine risk management dimension to the financing of rehabilitation.

May 1, 2004

By E. Chin

The countries of Asia and the Pacific have large resources of diverse minerals. Australia and China have extensive mineralization that are commercially being exploited. The major minerals in Australia with known reserves adequate for both domestic demand and export markets include bauxite, clays, copper, diamond, gold, iron ore, lead, manganese, mineral sands (titanium minerals), nickel, salt, silver, tin, uranium, and zinc. China is the world leader in proven reserves of antimony, barite, magnesite, molybdenum, rare earths, titanium (ilmenite), tungsten, and vanadium. It also has about 55 billion tons of iron ore, albeit with an average grade of only 30 % to 35 % elemental iron content. With the exception of chromium and copper, China has significant resources of a wide array of minerals and metals, based on its production and/or export capability for these commodities. Additionally, India has significant resources of bauxite and mineral sands; Indonesia, bauxite, copper, nickel, and tin; Malaysia, tin and associated titanium; Mongolia, copper, fluorspar, and lead-zinc; New Caledonia, nickel; New Zealand, gold and iron sand; North Korea, magnesite; Papua New Guinea, copper, gold and mineral sands; Philippines, copper, chromite, and gold; and Sri Lanka, gemstones. Moreover, there appears to be extensive mineralization III Burma (Myanmar), Cambodia, Laos, Thailand, and Vietnam, but they have yet to be definitively delineated.

Jan 1, 1994

By Detnet Solutions

1. “Daisy-Chain” concept The term “daisy-chain” stems from the fact that when the HotShot? detonators are connected there is a chain or electrical path for electrical current to flow from detonator A to detonator B, detonator B to detonator C etc until the path is terminated by an electrical means. The “daisy-chain” concept has long been used in electronic detonator systems, historically used in Expert Explosives’ ExEx 1000 5/6 wire system and currently in use in African Explosives Limited (AEL’s) Electrodet? electronic detonator system and has been adopted as the basis upon which the “auto-programmability” of the HotShot? electronic detonator system functions. HotShot? Detonators are connected to each other in a string, completing a “daisy chain”, and during the auto-detection mode of the control equipment, it is possible for the equipment to determine the order of hookup of the detonators as well as map the entire blast layout. The auxiliary components (Row Controllers & Branch Controllers) assist the control equipment in mapping the entire blast by indicating different points on the blast, i.e. The inflection point of a row of blast holes on a closed chevron timing pattern, the beginning of row of blast holes on open chevron timing pattern and extra blast holes or extra blast rows.

Jan 1, 2004

By Mark L. Chatman

This report presents an economic mineral assessment and Inventory of mines and prospects In the approximately 176,000-acre Patagonia Mountains-Canelo Hills Unit of Coronado National Forest. Deposits or areas most likely to experience future development are characterized in terms of their economics, based on data acquired by the author from a variety of sources, and supplemented by USBM field data collected by other workers in 1990 and 1991. Numerous mine maps, rock-chip sample assays, and detailed descriptions of mine and prospect sites are in this report and appendixes. Heavy but sporadic mining, mainly between the 1850's and 1950's was nearly all confined to the Patagonia Mountains. High-grade sulfide veins, replacements, and skarn deposits accounted for most of the production, which included large quantities of zinc, lead, copper, and silver, and considerable quantities of gold. Small Quantities of molybdenum, manganese, tungsten, and placer gold have been mined. Most of the traditionally mined metalliferous sites will not see future activity due to the low tonnages present and removal of most high-grade rock. Possible future development areas include copper porphyries and breccia pipes; most are too deeply buried for current development. Localities where similar deposits may be concealed are identified.

Jan 1, 1994

By J. Best, K. Gallant

This paper explores the age-old concept of mine-mill reconciliation from a new perspective. Advances in reconciliation processes have been slow to materialize because in the quest for “rightness”, engineers, geologists and metallurgists have become entrenched in their viewpoints, dutifully performing to the metrics and expectations imposed upon them by the siloed organization. Moreover, reconciliation has not been viewed as a primary value creator, but an accounting non-value added task. In reality, the knowledge from reconciliation can significantly enhance yields. Critical review of the direct variables (tons, grade, etc.) and other less-obvious variables (incentives, communication, etc.) reveal a complex web of barriers to be cleared by management in order to realize benefits. Also, mineralogical reconciliation methods may offer renewed faith in the process.

Jan 1, 2004

By M. G. Irish, E. E. Vidal, M. J. Jahraus, P. R. Taylor

An experimental system has been designed to monitor on-line variations of leaching parameters in a closed circuit of cyanide leaching solutions and gold bearing ores. Experiments performed to deter-mine variations in some important leaching parameters of the solution: pH, dissolved oxygen, free cyanide, oxidation/reduction potential, gold content, temperature, pressure and solution chemistry. By comparing results obtained when the leaching solution is allowed to become acid or kept basic, it was possible to infer the chemical reactions that occurred between the solution and the ores.

Jan 1, 2004

By D Brown, Z Tabor

Projects must be flexible to account for the rapid development of new technologies and changing stakeholder expectations. Coupled with calls for bleeding-edge solutions, customers, shareholders, and regulators demand robust, safe products and systems-of-systems. Developing and integrating these solutions is becoming increasingly complex and maintaining the flexibility required to ‘pivot’ to effective solutions can be a serious challenge. The necessary flexibility is fundamental to the Agile ethos, and this family of methodologies therefore offers a potential solution to this challenge (Beedle et al, 2001). These have traditionally been delivered with systems engineering applied through a Waterfall methodology. Agile Systems Engineering combines both approaches and presents a means to achieve these goals without compromising flexibility, quality or safety. A robust methodology for the application of Agile Systems Engineering is required to enhance practical outcomes and reduce risk for real-world mining projects.

Sep 1, 2024

By S Jahanshahi, D R. Swinbourne

The classical metal-slag-gas equilibrium technique was used to study the thermodynamic activity of cobalt, iron and their oxides in iron silicate based slags containing under controlled oxygen potential (3.70 x 10-8 to 2.95 x 10-7 atm) at 1573 K. The measured activity of cobalt oxide in FeOx-25 wt per cent SiO2 slags showed positive deviation from ideal behaviour for melts with up to ten wt per cent CoO. At higher silica contents, the behaviour became closer to ideal and in accord with previous studies on silica saturated slags. The activity coefficient of FeO in these slags had virtually no dependence on the CoO content. Partial substitution of silica by lime resulted in an increase of the activities and activity coefficients of CoO, FeO, Fe2O3 and Fe3O4. The results indicate that saturation of the slag with a magnetite phase occurs at CaO contents of five wt per cent and higher. Phase equilibria studies SiO2-FeO-Fe2O3-CaO slags containing cobalt were also carried out using the drop-quench technique. Results from these experiments confirmed the formation of a magnetite solid solution containing about three wt per cent CoO at lime contents of five wt per cent and higher at 1573 K and 2.9 x 10-7 atm of oxygen.

Jan 1, 2000

A variety of environmental financial assurance instruments are in use across the globe. This paper reviews some of the more common forms currently used in New Zealand, Canada, USA and Australia. In order to be effective, the form of assurance instrument selected needs to be aligned with a countryÆs specific environmental objectives, geography and political climates and also allow for a healthy investment climate. Industry and Government both have a strong interest in ensuring financial assurance criteria meet these objectives.   Recently Golder Associates have been involved in financial assurance assessments for various mining and quarrying companies across the South Island. Multiple stakeholders and regulatory agencies can make the setting of effective and fair financial assurance criteria a complex exercise for both regulatory agencies and industry.  The author relates experience gained in assessing financial assurance under current New Zealand legislation (RMA, 1991), effectively dealing with issues such as ôdouble bondingö and overviews potential approaches to dealing with transitional issues for historic and existing operating mine sites.

Jan 1, 2006

By Donald W. Stever

In 1995 I was asked to participate in a litigation matter between a corporation and its insurance carriers concerning insurance coverage for remedial costs at a large, environmentally contaminated closed-down former industrial facility. One of the buildings on this site became known to the lawyers representing the company as “the infamous Building 8”. This building housed millions of documents retrieved from various locations at the facility while it was being shut down. It became apparent that the facility management had no document destruction policy, and thus Building 8 contained internal memoranda, notes, copies of correspondence, permits, operating records, inventory records, and the like from fifty years of operation. Needless to say, some of these documents, all of which were subject to discovery by the insurance companies in the litigation, contained material that was less than helpful to the company’s case. Of course, there were also a few helpful documents, but the overall usefulness of these records was outweighed by the negative impact they had on the conduct of the litigation. A second example involves e-mail. Several years ago, acting on an anonymous complaint that we later discovered was made by a disgruntled former employee who had been fired, a small army of federal environmental investigators descended on a client’s operating facility and, armed with a search warrant, literally commandeered the facility’s EH&S department. The investigators impounded the computers of the EH&S personnel and extracted all of the data from the hard drives of those PCs, as well as all EH&S related files from the hard drives of several servers used by the facility. These computers contained many years’ worth of stored e-mails, draft letters and memoranda, and other documents that provided grist for a four and one-half year criminal grand jury investigation of the facility and its EH&S staff. Both of these companies would have benefited from following a rigorous, enforceable, corporate records policy. Here is a third problem. My client had, during the 1960s, made a brief, and unprofitable foray into the nuclear fuel processing business. It ultimately sold the subsidiary, and was forced to give the purchasing company a broad indemnity against future liability. As might be expected, years later the facility was found to have considerable soil and ground water contamination both by chlorinated solvents and low-level radioactive material. Several years into the remediation program, my client discovered a tractor-trailer load of files, apparently removed from the subject facility, sitting in a parked trailer in a company-owned lot 300 miles away from the facility, where they had been for nearly thirty years. These documents were not helpful to the client, but had to be reviewed, at considerable cost, by paralegals. Moreover, several of the boxes turned out to have been mildly radioactive, setting off a chain of health and safety issues that consumed tens of thousands of dollars of legal expenses before they were resolved. Today, formal, enforceable corporate records management programs have become an extremely important element of overall corporate management. What was for most of the last century little more than a low level warehousing function is now a critical, actively managed, operating function that affects every level of corporate management. The rapid assimilation into corporate culture of electronic document management and the prevalence of e-email as the primary means of internal communication have created records management complexities the likes of which were not even conceived of fifteen years ago. Record preservation and destruction are no longer matters that can be handled on an ad-hoc decision making basis. Because of regulatory requirements affecting various classes of documents and the litigation consequences of ad hoc retention and destruction of corporate business records, and the need to have the ability to quickly retrieve documents in either a litigation or business negotiation context, a set of records management norms have evolved over time that have become the core elements of virtually every corporate records program. However, notwithstanding the existence of a set of norms (which are the basic elements of a

Jan 1, 2005

By M. Dobbins

The advent of the more efficient and effective rare-earth roll (RER) separator in the early 1980s began a new era of dry magnetic separation. The RER units quickly became the separator of choice within the materials processing industry. Though RER separators are now commonplace throughout the world, only modest advancements have been made to the original design. This paper details recent, more significant, rare-earth magnetic separation developments. These developments maintain the best features of existing technology while minimizing shortcomings. The discussion includes discerning features that aid in better metallurgical performance. Also discussed are improved mechanical aspects that allow for both easier operation and maintenance. Performance details from various test programs are included.

Jan 1, 2010

By C. J. Brown

Since its commercialization thirty years ago, the Recoflo® short bed ion exchange process has been extensively utilized for the recovery of a wide variety of acids and metal salts. In addition to a reduction in resin bed height from 200 cm to 300 cm to 15 cm to 60 cm, the process has a number of features such as utilization of fine mesh resins in a compressed bed which together make it ideal for a number of applications. The process has been extensively exploited, for example, in the metal finishing industry for recovery of valuable chemicals from electroplating, anodizing, etching and pickling wastes. More recently, it has also been applied in the primary metals industry for purification of copper electrolytes and metals recovery from leachates. The paper discusses several of these applications and some of the issues that were found to be key to their success.

Jan 1, 2004

By Basak Anameric

This study reports preliminary feasibility investigations for utilization of the selective carbothermic reduction and smelting (SCRS) processing scheme to beneficiate low-grade iron-manganese (Fe-Mn) mineral deposits from MN, USA. The study includes laboratory-scale demonstrations using an induction furnace and production of various products by manipulation of operational parameters. The products include alternative iron (Alt Fe), high carbon ferromanganese (HC FeMn), alternative silicomanganese (Alt SiMn), and upgraded manganese concentrate (Mn conc). All of these products have commercial value and can be used in various applications as raw materials.

Nov 23, 2020

By R. W. Lawrence, J. B. Austin, P. B. Marchant, J. T. Chapman

"Biohydrometallurgy is the use of microbiological reactions to assist in the extraction of metals. Bioleaching offers an innovative alternative for the treatment of refractory gold-bearing sulphides (1). One particular cost advantage of bioleaching is the potential to enhance gold extraction after only partial sulphide oxidation. The apparent selective sulphide oxidation is more prevalent where the refractory gold is associated with arsenic and antimony (2). Oxidation of the pyrite minerals and arsenopyrite at different oxidation rates can result in high gold extractions at relatively low levels of sulphide oxidation due to preferential, or selective, oxidation of the arsenic mineral. Arsenic extraction rates in a bioleach process typically exceed the iron extraction rate. Therefore, in concentrates in which the precious metals are principally associated with arsenic minerals, liberation of the precious metals may be possible with high recoveries and less than complete sulphide oxidation. The capital and operating cost advantages of partial sulphide oxidation are inherently obvious and are briefly illustrated herein.Ultra fine milling (UFM) is another alternative for enhancing gold extraction from refractory sulphides. Some refractory gold is simply particle size sensitive and UFM can improve gold extraction without the need for costly sulphide oxidation (3). Fine grinding technology for enhanced gold recovery developed by Metprotech, South Africa, is currently producing 2 - 4 micron ground product using a single pass, stirred ball mill. Proper application engineering has ensured that plug flow occurs through the mill. Plug flow from the feed inlet at the bottom of the reactor ensures that short circuiting of feed does not occur and as a result, the mill product does not require classification.A combination of UFM as a pretreatment for bioleaching could provide a mechanism for enhanced selective sulphide biooxidation and/or increased overall gold extraction following biooxidation due to improved particle liberation ( 4). The effect of UFM on biooxidation costs will be discussed. Only sulphide concentrates are considered herein for application of UFM in combination with biooxidation."

Jan 1, 1990

By John Ralston, Stephen Grano, Yongjun Peng, Daniel Fornasiero

"A specially designed mill which allowed the control of pH throughout grinding was used to study the effect of rgrinding conditions on galena flotation and galena separation from pyrite. The various reactions occurring on the mineral surface were investigated by a range of techniques, including OH- addition to maintain the grinding pH, EDTA extraction, XPS and ToF-SIMS measurements.Galena flotation and galena separation from pyrite were strongly dependent on the metal oxidation species produced on galena and pyrite surfaces under different grinding conditions. Iron oxidation species depressed both galena and pyrite flotation, whilst lead oxidation species activated pyrite but had little effect on galena. Optimum galena flotation and galena selectivity against pyrite were achieved by selecting grinding conditions that enabled lead and iron oxidation production to be controlled."

Jan 1, 2003

By Scott Horton

In no Confederation of Independent States (CIS) country does the mining sector play quite so commanding a role as in the mountainous Central Asian republic of Kyrgyzstan. Its president, Askar Akayev, says he would like to develop his country into "a Central Asian Switzerland." However, in Switzerland, the gold is largely under the street along Zurich's renowned Bahnhofstrasse. In Kyrgyzstan, though, the gold is still in the mountains. Accordingly, Kyrgyzstan's recent adoption of a comprehensive new mining law has attracted widespread attention. Akayev recently completed a tour of the United States. His visit drew large crowds from the business community at events staged in New York and Washington, DC. The success can be attributed as much to the attractiveness of Kyrgyzstan's min¬ing sector as to the personal charms of the nation's president. Led by a half-billion-dollar investment by Canada's uranium giant Cameco, the mining sector is leading Kyrgyzstan's economic revival. And Bishkek is beginning to show some of the same signs of a "boom town" that already mark its Kazak neighbor, Almaty. Mercedes and BMWs already outnumber the Volgas on Bishkek's major traffic arteries. After nearly two years of debates involving government advisors and a final round of deliberation in Parliament, Kyrgyzstan finally adopted its second mining law. This followed quickly in the wake of measures enacted in neighboring Kazakstan and proposed in Russia. Kyrgyzstan's new law replaces the 1992 law "On Mineral Resources." It was one of the first enactments of an independent Kyrgyzstan. The 1992 law made a major contribution to the introduction of free-market economics in the country by ending the state monopoly over mineral exploration and development. It also laid the groundwork for an independent mining industry. According to Kyrgyz government reports, Kyrgyzstan has about 270 commercially viable deposits of almost 40 types of mineral resources. These include oil, gas, coal, precious-, nonferrous-, ferrous-, rare- and basemetals. However, the nation's key draw is gold. Since enactment of the first law, the government has issued more than 100 licenses for geological prospecting for and development of established deposits of gold.

Jan 1, 1998