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By Marcus Digre

The autogenous grinding method has been progressively employed in mineral dressing plants during the last 15 years. The term has been used with somewhat different meanings (1), (2), (3). In this paper the author will use it in the most restricted way, for processes where run-of-mine ore (rock) in one step is reduced to a grind product by the action of the ore itself without any other grinding media present. The pebble grinding process where the major part of the ore enters the mill as finely crushed product which is ground further with selected coarse ore pieces acting as grinding media, is not considered autogenous grinding. Processes where a minor amount extraneous media as steel-balls is added to supplement an autogenous mill charge will be called semiautogenous. Other terms need also to be defined. "Mill charge" will be used about the active part of the mill content which performs the grinding, that is the steel balls in ball grinding and the coarse ore pieces in pebble and autogenous grinding. The interstitial nearly finished material is not included in the term "mill charge", and for the wet grinding operations is called the "mill pulp' The term "pebble" will be used for any rounded ore or rock piece in the mill charge whether it is an autogenous or a pebble grinding operation.

Jan 1, 1970

By Tim O’Neil

The earthmover tire shortage has been a case of bust and boom for the tire industry. Tire producers were unwilling to invest ahead of the mining boom. In their defense, though, the metals sector of the mining industry tends to be cyclic, tire manufacturers are not prescient. Until two years ago, low tire demand depressed prices. The incentive to invest in new, big-tire capacity was almost nonexistent, according to Prashant Prabhu, president of Michelin Earthmover Tire worldwide. “There has been very poor anticipation or a miscaluation of the amplitude of the (tire) demand on the part of just about everybody,” said Prabhu. What a turnaround. The earthmover tire market has grown by 30 percent over the past two years. Now there are not enough earth-mover tires and likely won’t be for the next two years. Goodyear said it was offering customers bias-ply tires when it could not supply enough radial-ply tires. Komatsu said it lost equipment sales because it could not provide the tires that customers requested. Volvo and Caterpillar said they are delivering some vehicles without tires, either promising tires later or leaving the customers – mine operators – to find their own rubber.

Jan 1, 2006

By T. Gupta, T. Ghosh

Rare earth elements (REEs) and their compounds are essential in a multitude of mundane and sophisticated applications such as renewable energy technologies, catalysts, medicine, and defense applications. The global supply deficit could be attributed to the destabilization of REE market that has, as a result, incentivized indigenous production of REEs. Cost-effective and environmentally benign opportunities are being explored for the production of REEs from non-conventional mineral sources including coal and coal by-products to stabilize the supply chain. Coal from Healy coal mine and Wishbone Hill deposits in Alaska have been quantified for REEs and were found to possess elevated total REE concentrations as compared to world average levels (60– 70 ppm). The objective of the study was to concentrate the REEs in the froth phase by froth-flotation of the fine size fraction (< 75 μm). A Box-Behnken design of experiment was employed to ascertain the main and interaction effects of operational parameters on response variable by analyzing 3D response surfaces. Experiments were carried out to maximize REE recovery and concentration by modeling and optimization of three operating variables (frother dosage, pulp density (% solids), and collector dosage). Based on the results, the optimum flotation conditions for maximum recovery at an elevated concentration of REEs in the froth fraction was obtained at 4.2% solids and 32.7 ppm of frother dosage for Healy sample and 10% solids and 37.9 ppm of frother dosage for Wishbone Hill coal sample. The quadratic relationship between the input and response variable was found to be independent of collector dosage suggesting good surface hydrophobicity and floatability of the two coal samples.

By M. Arias

"An attractive foreign investment legislation, an anti-mining framework in the jurisdiction where a head office is located, the geographical location of the mineral resources, a country that offers the technology needed by the industry for its operations -- these are some of the many factors that make mining and mineral exploration a global business. It is precisely in the complexity of this new era of globalization and market environment, that sustainability initiatives are challenged. Responsible management of mineral exploration and mining is no longer defined by the use of efficient technology and resource management. Sustainability is not only a report compliance exercise or a green revolution. Sustainability is like any business, a long term profitable proposition. This new approach encompasses four pillars: social, economic, environment, and culture. This new approach connects humans and corporations; it is the way to engage, respect and improve relations with the people with whom we work and our neighbours."

Jan 1, 2011

By Ehab Gomaa, K. A. El‑Nagdy

Backfilling material such as tailing (mine wastes) mixing with cement or gypsum has grown throughout the world’s underground mines. However, despite their growing popularity, the typical hydraulic and mechanical fill types utilized in many mines still exist. Deep underground mining has increased due to the lack of commercial minerals nearby. Mine wastes were considered the main part of backfilling to prevent environmental pollution, ground subsidence after mine abandonment, and mine collapse during deeper extraction phases. The cemented backfill technique is the principal technique used in underground mines, which include cement with fly ash and/or filter dust, cement with tailing material and fly ash, gypsum with fly ash, and synthetic anhydrite with fly ash and have been reviewed. It has concluded that a backfilling material must be selected based on further goals, available material near the mine site, and economic factors. This paper analyzes different backfill material mixtures to create a technique that will increase safety in underground mining conditions and foresees an appropriate formula that gives high uniaxial compressive strength. The multiple linear regression (MLR) on the collected data from the experimental works to construct the relationship between the uniaxial compressive strength (UCS) of the mixture and the components of the backfilling and the prediction formula for expected compressive strength was obtained. The results revealed that the predicted regression equation was robust and reliable to predict the (UCS) for the new components of the filling (cement (CE), filter dust (FD), water content (WC), and time (T)).

Oct 3, 2023

Partition models are commonly used to assess the separation performance of circuits incorporating density-based processes. Unfortunately, this useful tool has traditionally been overlooked by the heavy minerals sands industry due to difficulties associated with the use of toxic dense liquids. In the present study, this problem has been avoided via the development of partition models based on experimental data from microscopic grain-counts. This technique, which uses different mineral species as density tracers, provides a new tool for evaluating the multi-stage circuits that are required to successfully upgrade heavy mineral sands. The partition model approach easily identifies shortcomings of existing circuits and, when used with conjunction with linear circuit analysis, provides tremendous insight regarding the optimum arrangement of unit operations in terms of separation efficiency and plant throughput capacity. An industrial case involving the redesign of a heavy mineral sand spiral plant is presented to demonstrate the utility of these process engineering tools in plant optimization.

Jan 1, 2009

By 1980, the U.S. mining community had reached a broad consensus regarding coal pillar design. The pillar load could be estimated from tributary area theory, and the pillar strength from empirical formulas and laboratory coal strength testing. Then the growth of longwall mining required new thinking. Recently, powerful design methods have emerged from analysis of large data bases of real-world pillar successes and failures. These include the Analysis of Retreat Mining Pillar Stability (ARMPS), the Analysis of Longwall Pillar Stability (ALPS), the Mark-Bieniawski rectangular pillar strength formula, and guidelines for preventing massive pillar collapses. Sophisticated numerical models have also helped transform the pillar design landscape. In the process, our understanding of pillar mechanics has been greatly enriched. A new paradigm divides pillar failure into three categories:

Jan 1, 1999

By J. P. Brady

A major spontaneous combustion incident occurred in the sealed goaf of the SL3 Panel; Southland Colliery in 2003 resulting in the loss of a longwall and sealing of the mine. The most important issue for the new owners, Yancoal Australia Pty. Ltd, was to effectively manage the atmosphere in the fire affected sealed area. This atmosphere comprised of flammable gases, the products of combustion and excessive levels of oxygen due to pressure differentials across the panel isolation seals with a potential ignition source associated with the residual spontaneous combustion event. The challenges were met in the first instance by the erection of pressure balance chambers with limited success. The problem was not solved until the pressure chambers were pressurized using a Floxal Nitrogen Plant supplied by Air Liquide Australia. Given the success of this approach on a small scale, a higher capacity Air Liquide Floxal Unit was acquired to manage spontaneous combustion at the recommencement of longwall mining operations. This provided the ability to pressurize pressure chambers that were installed in the Maingate Seals behind the face of the adjacent Longwall Block effectively preventing the ingress of oxygen and permitting the goaf to self inert in a reasonable time period. This paper summarizes a new proactive method of mitigating the risks associated with active and sealed goaves. Proactive management of these areas using low flow nitrogen into pressure chambers to maintain a positive pressure has eliminated typical reliance in explosion proof or explosion resistance seals as the primary control.

Jan 1, 2009

By Trevor R. Ellis

The extractive industries addition to the International Valuation Standards (IVS) is scheduled for publication in the next edition of the IVS book in January 2005. This will provide guidance for valuation of minerals and petroleum industry assets of all types for all appraisal uses. It will provide asset valuation support to the International Financial Reporting Standards for the stock markets of the world, and a global umbrella standard which can be supplemented for local needs by institutes and regulators. This paper discusses implementation of the IVS within the minerals industry and important issues that the industry should confront.

Jan 1, 2005

By S. Shi, J. Y. Hwang, B. Li

Silver, copper, and zinc are commonly known elements with antibacterial and antifungal capabilities. Attempts have been made to dope silver on minerals, glass, and ceramics and the resulting materials have been investigated for their antibacterial and antifungal properties. Since silver is expensive and very reactive, silver doped materials have been found inappropriate in some applications. Copper-vermiculite is investigated as an alternative. Vermiculite has high cation exchange capacity on the magnesium ion in the crystal structure. Copper ion may have a high tendency to replace magnesium because of similar charge interference and ionic radius. Copper-vermiculite is prepared by reacting vermiculite and copper chloride solution. By impregnating copper ions into the nanometer openings between the layers of vermiculite, it is possible to render the composite with antibacterial functions if the copper ions could be released gradually from the composite. The antibacterial efficiency of Cu-vermiculite against Escherichia coli was studied using the Halo method. The results show that Cu-vermiculite is effective for preventing the reproduction of the bacteria. Heat treatment of Cu-vermiculite at up to 400°C does not show significant changes in antibacterial activities.

Jan 1, 2002

By Donald A. Ranta

Every mineral project or mine is based on a geologic entity-an ore (mineral) deposit. A well-defined mineral deposit and its associated geologic characteristics are the only aspects of a project that cannot be altered. Mine plans can be modified to exploit the deposit using alternative approaches and yielding similar results. A variety of processing methods also are often available producing generally comparable results. Major modifications can be made to other aspects of the project without substantially changing project economics. However, all engineering and metallurgical aspects of a mine must be accommodated to the spe¬cific location and geologic characteristics of the deposit. Geologic data and interpretations form the foundation for both mine evaluation and mine production by providing esti¬mates of reserves and essential information for mine planning and process design or control. Proper geologic work requires a keen awareness of and an ability to anticipate the technical requirements of geotechnical engineers, hydrologists, mining engineers, metallurgists, and other specialists. Geologists are inte-

Jan 1, 2008

By Aki Fujii, Hiroshi Dobashi, Mitsuro Matsuda, Yoshinari Kondo

INTRODUCTION The Metropolitan Expressway Central Circular Route with a total length of approximately 47 km is located outside the Inner Circular Route of Tokyo (at a radius of approximately 8 km from the city center). Sections with a length of approximately26 km, slightly less than 60% of the total length, on the east and north sides are in ser-vice. Completing the Central Circular Route (Figure 1) is expected to enable through traffic concentrated at the city center to get around, and to form a well balanced trans-port network, which will alleviate traffic congestion considerably. The Central Circular Shinjuku Route, a section with a length of approximately 11 km on the west side, is now being constructed at a fast pace. The route is being built mainly by the shield tunneling method to carry out work smoothly under a trunk highway carrying heavy traffic and to reduce adverse effects of tunneling work on residents in the neighborhood. Shield tunnels have recently been becoming longer and deeper, and no secondary linings have been used in an increasing number of cases because of the over-crowding of cities or the reduction of budgets for public works. Economical, durable and high-quality segments have been required for linings of shield tunnels. Segments are made of concrete, steel, cast iron or combination thereof. Concrete segments are generally used in shield tunnels of medium to large diameter. Concrete segments are highly durable and resistant to compression, so they are highly resistant to earth pres-sure, water pressure and jack thrust. They are, however, heavy and have low tensile strength, so they are brittle and their corners are likely to spall. Concrete segments should therefore be handled carefully.[1] The authors have developed a steel fiber reinforced highly flowable concrete segment (referred as SFRC segment) that overcomes the weaknesses of concrete segments[2] to construct economical, durable and high-quality linings. SFRC segments have been applied to outbound sections SJ51 through SJ53 of the Central Circular Shinjuku Route. Unlike conventional concrete segments (referred as conventional RC segments), SFRC segments are made of steel fiber reinforced self-compacting highly flowable concrete. SFRC segments require less reinforcing bars than conventional RC segments because steel fibers are expected to work as reinforcements. Steel fiber reinforced concrete is a composite material that overcomes the brittleness of plain concrete, and has higher resistance to bending, tension and shear than

Jan 1, 2007

Extending an organization?s knowledge base throughout the entire enterprise can improve operations. Until recently, though, field operations were often left out of the information loop, as extending high-bandwidth communications into harsh environments often proved impossible due to thermal extremes, physical hazards and caustic chemicals. However, advances in the design and manufacture of rugged fiberoptic cables have now enabled the successful installation of 10-gigabit transmission links to places such as mining operations. The experience of Consol Energy exemplifies how plant managers can successfully enlist ruggedized tight buffered cables to help carry the efficiency of ERP communications into even the most challenging work environments. ?As part of our ERP implementation, we extended our corporate network underground into our mines using fi beroptic cable,? said Tom Prokop, manager-site support for Consol Energy. ?We?ve actually had rooffalls bury the cable between rocks and still did not lose data communications. Our maintenance personnel are now able to access our ERP system while underground at locations that can be up to 32 km (20 miles) away from their desks or the warehouse. Access to the corporate network allows them to order parts, look at electronic schematics, access monitoring data, no matter where they are in the mine. With a few hundred workers below ground, this immediate access translates into a time-savings that adds up in a hurry.?

Jan 1, 2009

By M. J. Fairweather, J. R. Egan, W. A. Meekel

Cominco Metals, in cooperation with two Canadian Universities and the Government of Canada, is developing applications for column flotation in the treatment of lead and zinc ores. Plant scale results at Polaris and pilot plant studies of Sullivan, Pine Point and Red Dog ores show column flotation to have significant advantages over conventional mechanical flotation for lead and zinc cleaning. Results from these ongoing studies are discussed in relation to ore texture, mineral recovery, impurity behaviour, scale-up and control.

Jan 1, 1988

By I. Demers

Doyon mine, Quebec, Canada evaluates the possibility of desulphurizing their tailings to produce material to be used in as cover over the acid generating tailings disposal site. Laboratory tests were conducted and showed that a single-layer cover made of desulphurized tailings placed over reactive tailings can prevent the generation of acid mine drainage. Modelling with the software Vadose/W was undertaken to optimize the design parameters, namely cover thickness, water table position, and residual sulphide content of desulphurized tailings following laboratory work. It was found that the optimal configuration includes a 1 m desulphurized tailings cover containing 0.8%S, with the water table kept at the interface between the reactive tailings and the cover. To maintain the cover performance to reduce oxygen flux towards acid-generating tailings even in the event of a long dry period, a sand layer is suggested to protect the cover from excessive evaporation. It is possible to reach the environmental objective chosen for Doyon mine (10 mol/m2/year) with the protective sand layer, even in extremely dry conditions.

Jan 1, 2008

By M. C. Fuerstenau

Collophane, cryptocrystalline fluor-apatite, is examined as a substrate for plant water and wastewater remediation. The attenuation of Fe3+, Fe2+, Hg2+, Pb2+, and Cd2+ is presented as a function of metal ion concentration, amount of collophane, initial pH and conditioning time. TCLP results for Pb2+contaminated collophane are presented. Mechanisms of adsorption for divalent and trivalent species are suggested.

Jan 1, 2001

By J. N. Murphy

The use of the National Science Teachers Association (NSTA) regional meetings as a forum to educate teachers on the role of minerals in our society has been immeasurably successful. Each year, on average about 3,500 to 4,000 teachers participate in each of the three regional NSTA meetings. At each of these meetings, nearly 2,000 teachers visit the “Minerals Coalition Booth” and receive free mineral samples and other educational support materials. Some rules of thumb for a successful booth at the NSTA are provided. Considering the level of effort for such a booth, are there alternatives? The NSTA also organizes a national annual meeting with attendance of about 20,000. All who have participated in a regional NSTA agree that the traditional approach of providing a mineral set and teacher materials for a substantial fraction of the 20,000 attendees is not feasible. Conceptual alternatives for minerals education at the national NSTA meeting are introduced and evaluated.

Jan 1, 2001

By Ray Brainard

Charleston Water System?s Daniel Island Extension Tunnel, initially thought to be the simplest of the four replacement tunnels to design and build, became the most challenging after the discovery of an unexpected 30-ft thick lens of sand in the normally consistent Cooper Marl while sinking a shaft on Daniel Island. This paper will explore the challenges involved with determining the extent of the unforeseen lens of sand, the accelerated boring program, and the redesign of the vertical alignment?keeping the alignment between the sand layer and the bottom of the Cooper River. It will describe how the challenges were overcome, and how the Owner, Engineer, and Contractor were able to team together to achieve the desired results.

By Yiming Sun

The 5-mile long Bay Tunnel is a major water supply facility to be constructed under the San Francisco Bay and adjacent marshlands between the San Andreas Fault to the west and the Hayward Fault to the east. The tunnel will have a two-pass lining system consisting of a watertight precast concrete segmental initial lining and a welded steel pipe final lining. Considering the Bay Tunnel?s location between two major active faults, the design earthquake produces a significant peak ground acceleration estimated at approximately 0.6g. To develop a design that can achieve the seismic performance objectives, full dynamic seismic analyses were performed using site-specific earthquake time histories. The analyses considered soil-structure interaction and an evaluation of the transverse and longitudinal effects of the design earthquake. This paper describes the seismic analyses and the design measures recommended to minimize potential adverse effects of the design earthquake on the tunnel final lining.

Jan 1, 2008

By J. Duran

Mining at Newmont Mining?s Phoenix?s Mine is currently done by surface operation in the Fortitude and Bonanza pits at a combined rate of approximately 100 kt/d (110,000 stpd). A portion of the orebodies targeted by these pits was mined previously by underground mining methods, dating back to the mid-to late-1800s. Most of the underground workings (voids) are located in the west central area of the Bonanza pit. The surface operation requires excavation through voids, and there is a risk of pit floor subsidence that has to be addressed. This article presents a review of the risk mitigation measures that were implemented to reduce risks to people and equipment working in the area.