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By A. S. Macfarlane

Over the last few years, and especially the last few months, issues relating to Corporate Governance in industry in general, and the Minerals industry in particular, have become increasingly topical, as a result of a number of scandals and failures. The development of International and National Codes for the reporting of Mineral Resources and Reserves began some years ago, and has been followed by more stringent Listing Rules for the Securities Exchanges, as well as more standardised formats and protocols for financial reporting of assets and activities. More recently, some countries have adopted Codes for the Valuation of Mineral Properties, which have focussed on standardisation of valuation approaches to be adopted, and the qualifications of people deemed competent to sign off such valuations. This process has not been without criticism, the main criticism being the proliferation of local standards and regulations, which are often difficult to apply and regulate, or which are too prescriptive for multinational mining companies to deal with. In South Africa, these concerns have been recognised, while at the same time a need has been identified to establish a Code which could be applied to South Africa, and the African continent as a whole. Such a development would necessitate that the Code satisfies the needs of the continent, but in a global context. This global context has already been set by the activities of the International Organisation of Securities Commissions, the International Valuations Standards Committee and the International Accounting Standards Board. This paper explains the progress and process that has been established in South Africa for this purpose, and highlights the key issues which are open to public debate, so that the process is inclusive and transparent, whilst at the same time it is consistent with international time frames, and provides a deliverable product that meets the desired objectives.

Jan 1, 2004

By Samer Sadek

The Georgia Department of Transportation (GDOT) undertook an exploratory feasibility study to one of the most ambitious tunneling projects in the United States. HNTB Corporation was retained to perform the study, deemed the Atlanta North-South Tunnel, which is approximately 7 miles long and consisting of four lanes (or six lanes) starting at the southern terminus of SR 400 extending to the south connecting with the northern terminus of I-675, providing substantial relief to the Downtown Connector (I-75/I-85), the most congested portion of Atlanta?s freeway system. This paper summarizes the analysis performed during the first phase of this challenging assignment which, if constructed, would be one of the longest roadway tunnels ever built in the United States.

By C. R. Hairfield

With ever rising energy costs, it is increasingly important for mines to operate with energy efficiency. As a large portion of a mine?s energy consumption is often attributed to the operation of mine ventilation fans, maintaining an efficient ventilation system is a critical pro-active way for mining companies to reduce power costs. A common way to measure a mine?s ventilation system efficiency is to calculate the volumetric efficiency, which is simply a calculation of the percentage of total mine air that is usefully employed for production. The purpose of this study is to document a nationwide comparison of the volumetric efficiency of U.S. underground coal mining operations. The results will aim to show just how efficient today?s coal mine ventilation systems are and what factors may be causing their various efficiencies and inefficiencies.

Jan 1, 2009

By P. Amelunxen

This paper presents the authors? personal experiences in the design and operation of moly separation circuits in copper-moly concentrators. Topics discussed include column cells versus mechanical cells; use of nitrogen; use of CO2 and sulfuric acid for pH modification; and general equipment selection and sizing. A benchmarking of main operating parameters for industrial plants is presented. Upgrading curves for commercial column and mechanical cleaning circuits are also presented, showing that with average flotation kinetics and rougher concentrate grades, technical grade concentrates can be easily achieved with five column cells operating in counter-current configuration.

Jan 1, 2009

By Syd S. Peng

Coal mine ground control is the science of the application of rock mechanics principles to coal mining operations. More acceptance of ground control techniques by the US coal mining industry has been seen in the 1980s. It has been demonstrated many times that a proper ground control design is key to a successful coal mining operation. However, numerous in-mine applications of various ground control techniques by the author indicate that cur¬rent techniques need improvement. The biggest problem in coal mine ground control is that miners are dealing with materials of rapidly varying properties and occurrence. And only the exposed surface can be identified positively. Thus, in attempting to solve the ground control problems, many unknown factors are assumed. Some of these problems deriving from such assumptions are discussed here. Coal pillars There are two types of coal pillars - barrier and chain pillars - depending on the purpose. Barrier pillars are those located between panels or sections or mines. Their objective is to isolate the mined-out effects of one from the other. Chain pillars are characteristic of room-and-pillar mining. They are designed to support the overburden load and protect the surrounding entries and crosscuts. Pillar design is the most popular and, frequently, the only ground control technique employed by coal operators for mine design. There are many pillar design formulae available (Bieniawski, 1983; Peng, 1986). Nearly all consider both size and width/height effects. Specifically, pillar strength decreases with increases in pillar size and increases with increase in the ratio of width to height. However, the manner of those changes varies with investigators. Consequently, the pillar size determined varies considerably from investigator to investigator. And the variation grows much more pronounced as the seam depth increases (Fig. 1). The question, then, is which one should be used? One may say each formula is developed for a particular coalfield. A particular formula may have been used to design a pillar, which has not failed. Does that mean it was over designed? Not necessarily, because no one can confirm its stated "safety factor." Recent case studies (Peng, 1986; Tang and Peng, 1988) show that all pillar formulae are too conservative for chain pillar design in room-and-pillar mines due to the following two problems: • Uncertainty about in situ pillar strength. All formulae employ uniaxial compressive strength of selected samples tested in the laboratory and scaled to that for underground pillars. The scaling factors are not well proven. In situ testings by Bieniawski (1969) suggested that 1.5 m (5 ft) pillars are representative of in situ pillars that, after being tested in various US coal mines, are not universally applicable. • Uncertainty about the actual loading on the pillar. The most frequently used tributary loading theory defines the loading as total overburden weight tributary to each pillar (from roofline to surface). This is too conservative when it applies to coal measure rocks. The overburden consists of layered strata of different stiffness. Many stiffer strata will self-support over small roof spans. Depending on the location of these strata above the coal seam, it will reduce pillar loading in various proportions. It follows that total structural analysis using, for instance, finite element method is more appropriate. It can take into account the interaction of roof and floor strata with coal. This has been demonstrated by Peng et al. (1986,1988) on several case studies. However, the validity of the finite element structural analysis depends on the accuracy of in

Jan 1, 1989

By Robert M. Matyas, P. E. Sperry, Robert J. Smith, A. A. Mathews

INTRODUCTION The first Dispute Review Board (DRB) was utilized on a tunnel project 20 years ago. Increasingly utilized on a wide range of construction projects, DRB's are becoming the norm on tunnel and underground projects. This paper summarizes the growth in this usage, uses observations and experience to establish that barriers to the utilization of DRB's are more perceived than real and that many arguments against the DRB concept are not valid, and notes some of the salient elements that should be considered in practice to optimize DRB effectiveness. The purpose of the paper is to provide an annotated checklist for current and prospective users. The basic concept, structure, and operation of DRB's are described elsewhere and will not be repeated here (ASCE, 1991). DISPUTE REVIEW BOARD USAGE A compilation of Dispute Review Board usage for tunnel and underground projects to January 1994 indicated use on 63 contracts with a cumulative construction value of $3.8 billion and a total of 60 disputes settled. As of that same date, DRB's were planned for another 63 contracts with an estimated construction value of $4.7 billion. (A listing of these 126 projects is available from the authors.) This success and popularity have spread to other civil projects as well as process and building construction. The increase in DRB usage has been exponential. See Figure 1.

Jan 1, 1995

By Stanley C. Suboleski

1977 was the modern day low point for productivity in the coal industry. At that time, no one could have predicted that the industry was about to enter a productivity rise that would continue unabated through the 1980s. Thirteen years later, the cause of this phenomenon is still not well understood. While many government studies focused on the fall in productivity from 1969 to 1977, none have been undertaken to explain the rise. Some of the likely causes of the gain in productivity during this period will be discussed here. An attempt will also be made to quantify the value of some of the technical innovations that have taken place. The remainder of the gain is assumed to come from non-technical sources. The nature of these sources, although largely non-quantifiable, is also discussed. Since the number of mines that have adopted the technical innovations noted here is largely unknown, the actual contribu¬tion of technological changes to the overall productivity gain can only be estimated.

Jan 1, 1990

By Michael Karmis

The International Conference on Sustainable Development Indicators in the Mineral Industries(SDIMI 2003) was held May 21-23, 2003 on the island of Milos, Greece. The objective of this international conference was to assist the mining and minerals industries in their global transition to sustainable development. The main theme of the conference was the development, monitoring and assessment of sustainable development criteria for mineral operations. Emerging technologies were also presented that can assist in the development of criteria and performance indicators.

Jan 1, 2003

The reduced need for traditionally trained and educated personnel in the mining industry is systemic to the changing mining industry. Our universities and other training institutions are doing just fine meeting the traditional skill needs required by the industry. But are the skill needs going to be the same in the near future? The answer may be NO!! Mining is changing: increased liabilities and costs of environmental and safety issues; lower grades of minerals in traditional mining activities; the advent of new bio-chemical processes and robotic equipment as more productive and economic alternatives; and, larger more sophisticated and automatic equipment. Engineering is more specific, accurate, precise and expensive. Measurement is more thorough and timely of progress, production, costs, and productivity. And we will be engaging in more undersea mining, possibly space bases processing, less human interaction, and more remote control of events than was ever thought possible in the past. This paper presents several of the systemic changes that are presently and will continue to change the face of mining. It will identify area where education and management will have to address these changes.

Jan 1, 2011

By Patrick J. Doig

The Lewis Street CSO Tunnel is an important element in the efforts of the Metropolitan Government of Nashville and Davidson County (Metro) to improve the treatment of waste-water in the area. The tunnel is approximately 1,675m (5,500ft) long with a finished diameter of 2,600mm(102inches). 116m (380ft) of tunnel was constructed in soil with the balance being in lime-stone rock. Excavation was with a 3,700 mm (12ft) diameter Jarva hydraulic shield in soil and a Jarva Mark 12 TBM in rock. The permanent lining of the tunnel comprised concrete pipe with steel end-rings and a vinyl liner. This paper describes the construction of the project with particular emphasis on the excavation and lining of the tunnel.

Jan 1, 1997

By J. W. Craven, M. Katom, K. M. McCaffery

At Ok Tedi, ore type and SAG feed size distribution vary widely and frequently. This makes control of the SAG mills by application of the power/pressure relationship difficult. Power logic has traditionally been conservative due to power spikes associated with rapid size distribution changes. A new expert system was installed in early 2000. The system incorporates multiple state fuzzy logic to deal with frequent and radical ore type and size variations, along with monitoring of motor temperatures. A short term power spike no longer warrants immediate radical action. This has resulted in increased mill throughput and improved circuit stability.

Jan 1, 2001

By J. J. Fallon

The subject is "Mergers, Acquisitions and Divestitures in Industrial Minerals, but my remarks could also be applied to new product development, resource development and other new business development activities. At the kernel of the subject is due diligence in major decision-making, that is, where major money amounts and a large corporate commitment are at stake. The "due diligence" means how carefully we do our homework before making the decision. The homework or feasibility study addresses different parts of the decision. In the industrial minerals business the study seeks to uncover the pros and cons in: o The mineral reserves, quantity, quality, mineability, access, etc. o The environmental impact of mining, processing and transporting. o The economics of operations. o Financial aspects o Legal aspects o Many other aspects o And -oh yes! the marketing aspects.

Jan 1, 1990

By R. P. Proulx

The Meikle Mine is a high grade, underground goldmine utilizing primary-secondary longhole open stoping with delayed backfill to produce 2700 tpd(3000 stpd) of ore. Hot and reactive ground conditions were encountered early on in the mine life. Ground temperatures up to 166°C (330°F) were measured. In the early stages of mining, the mine experienced premature detonations using different explosive products. The learning curve to safely mine this high-grade gold deposit in hot and severely reactive ground was indeed very steep. Currently, the Meikle Mine uses a special buffered bulk emulsion in all blasts to address hot and reactive ground concerns. In addition, exacting procedures are also followed to ensure safe work with explosives. The combination of new explosives technology and strict loading procedures permits high mine productivity with the highest degree of safety.

Jan 1, 2000

By Jennifer B. Leinart

Sixty percent of the mines responding to the sixth annual Mining Cost Service labor survey reported increases in wages averaging 3.4% over the preceding 12 months. Only one mine reported a decrease in wages and this was accompanied by initiation of a substantial profit-sharing plan. Thirty-nine percent reported no change in wages. Thirty-seven percent reported using some form of incentive bonus plan. Mining Cost Service annually surveys coal, metal, and industrial mineral mines throughout the United States. Information about wages, benefits, and incentive bonus plans is part of an extensive data collection program to monitor cost areas of significance to the mining industry. This year, 131 mines responded to the survey. The data is collected by sending questionnaires to personnel managers at active mining operations. The information included in this article was taken from the returned forms, from labor contracts provided by some of the mines, and from followup telephone calls. This year's data was collected between November 1988 and February 1989.

Jan 1, 1990

By Joshua Cole, Joshua Sovechles, Christian Cardoso, Guillermo Bermudez, Martta Hirsi, Joshua Dettamanti, Rabia Abbasi

The implementation of technological advancements in flotation is key to optimize performance in mining operations. Consequently, flotation cell’s performance is highly dependent on the effectiveness of the mixing mechanism. A more efficient flotation mixing mechanism is likely to improve metallurgical performance and optimize energy consumption, which is the motivation for Metso’s journey to develop the latest iteration of FloatForce®. Looking to test the new design at plant scale, Metso approached the Kennecott Copperton concentrator, which is continuously looking for different venues to improve metallurgical performance. In this context, a test campaign was conducted to implement this new flotation mixing mechanism in their rougher circuit during 2024. The industrial trial consisted of several sampling campaigns assessing different operational parameters for comparison purposes around a 300m3 flotation cell. The effect of the new flotation mixing mechanism on the cell’s power draw was also studied. The results of this trial at Kennecott are presented in this paper. Overall new flotation mixing mechanism, FloatForce+ was seen to perform as well as the original FloatForce.

Feb 1, 2025

By T. R. Ellis

The author attempted to concurrently apply the US Uniform Standards of Professional Appraisal Practice and the Australian VALMIN Code to a complex mineral property appraisal assignment. This led the author into many severe difficulties. These difficulties included the high standards needed in the work of others, and information and statements needed from the client. The exercise also highlighted many positive features of both documents. Some conflicts were found between the two documents. Implications and thoughts regarding the development of a set of US minerals appraisal standards are discussed.

Jan 1, 2000

By D. Noon

Mine production crews and drill-and-blast crews may be exposed to unexpected movement of ground when working under pit slopes. Without specialist geotechnical advice and appropriate measurement systems, mine crews are faced with conducting risk assessments and relying on subsequent controls that may or may not be adequate to ensure their safety. Mine crews need an ?early warning? monitoring system to give them the confidence that they will have time to walk out of the danger zone if the pit slope begins to move. Slope stability radar technology is used by mine geotechnical engineers to assess overall slope stability over an extended period, typically days or weeks, and to critically monitor slopes that are actively moving and may become unsafe. The complexity of slope stability radar allows for geotechnical engineers to assess movement types and movement rates across multiple work areas of a mine from long ranges, with alarm capability to a central location. However there are many mine work areas where production and drill-and blast crews are not adequately covered or alarmed by slope stability radar systems. What is required is an easy-to-use, short-range, fast-scanning tool that can be operated directly by a work crew and can provide a local alarm with sufficient warning when a wall movement occurs within the work area. The Work Area Monitor (WAM) concept has been developed specifically to be operated by a mine production crew. The system comprises a sensitive, fast-scanning radar coupled with a high-resolution camera, built into a mine-standard light vehicle. The system has been designed specifically for ease of use with the output being a local area alarm to warn workers of slope movement in their vicinity, as opposed to the broader pit monitoring and long-term deformation measurements of the known slope stability radar systems.

Jan 1, 2012

By H. Lyn Bourne

This marks the 15th consecutive year for this column. During 1995, readers were asked to supply royalty data for construction raw materials especially for states where none is available. The response was discouraging and royalty data are still missing for several states for either sand and gravel or crushed stone. Several readers have said that this article has merit but more new information is needed to justify its continuation. Several articles and pieces of news relative to mineral royalties appeared in the trade journals. R. Lee Aston (E&MJ, November, 1995, p. 16N) described South Australian royalties as amended by the government in1994. The royalty rate (a percentage) was lowered but the assessed value for minerals was raised and the current rate amounts to 20 cents//t (18 cents/st).

Jan 1, 1996

By M. Pawlik

The rheological properties of mineral suspensions affect the design and operation of transport, mixing, size classification, grinding, gravity concentration, flotation and de-watering systems. In many cases, the rheological properties can be modified to improve processing through the addition of chemical additives. These additives may be either organic or inorganic and generally affect the state of particle aggregation or dispersion. Inorganic modifiers act primarily by affecting the surface charge of mineral particles and thus control the magnitude of electrostatic attraction/repulsion between particles. The action of organic additives (polymers and surfactants) is a combination of electrostatic and steric forces – the latter being related to the molecular weight of these reagents. While low molecular weight polymers are dispersants (viscosity reducers), high molecular weight polymers are likely to induce flocculation and increase yield stress.

Jan 1, 2004

By F. B. Kuhnow

When performing blasting operations in open pit settings, energy is released and transmitted through the geology. Some negative effects can have significant impacts on mining operations and adversely affect mine production. This technical paper presents recommendations for blast design to prevent damage due to ground motion from blasting on adjacent concrete structures of underground operations. The paper includes a case study describing a problem regarding an open pit mine expansion and asks whether production blasting will damage concrete shaft structures due to blast stress waves and blastinduced ground motion. Based on the results, a set of criteria is provided to implement in current and future mining operations that involve blasting near underground concrete structures. A set of techniques on how to improve vibration levels for safe operations is also presented. Knowledge of particle velocity and wave propagation for site-specific circumstances to determine a safe level of vibration is recommended. Emphasis is placed on making use of electronic detonators and early delay detonators to achieve successful levels of vibration. A dynamic analysis is necessary to determine if vibration from blasting can damage the concrete shaft structure. When reinforced concrete structures are subject to blast loading, both concrete and steel are subject to very high strain rates. As opposed to static loads, when subject to high strain rate loads these materials increase their strength significantly. In fact, they increase by more than 50% for reinforcing steel, by more than 100% for concrete in compression, and by more than 600% for concrete in tension. This finding is of significant importance in mining operations because it allows an increase in flexural capacity of individual members as a result of high strain rates. Therefore, an elevated ground vibration (PPV) or particle velocity is permissible when blasting takes place near concrete structures.

Jan 1, 2014