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By A. J. Basu

Computer assisted mine planning and design applications are routinely used by many Australian mining companies, However, the design process requires human expertise to recognize and evaluate the potential pitfalls. This paper introduces the application of a commercial optimization software (WHITTLE 4D) for strategic planning of an open pit mine in Western Australia. The authors present their experience in intelligent application of the optimization program while incorporating many technical and nontechnical obstacles. This paper provides some guidelines on how to apply the optimization software without loosing sight of practicalities. Moreover, this paper also shows how to build project evaluation guidelines for non-experts.

Jan 1, 1997

By B. T. Darnton

Gravity concentration at the Pegasus Gold Montana Tunnels Mine was initiated in late June, 1991 with the commissioning of a coarse gold scalping circuit that processes a small portion of the ball mill circulating load. The primary objective for the circuit was to reduce the risk of gold particles advancing to flotation that are too coarse to float. The secondary objective was to enhance overall gold recovery and payable gold ounces in a cost effective manner. The gravity circuit has proven itself to be a major success. The above mentioned goals have been achieved, and they have been maintained at record throughput rates that are 30% higher than when the circuit was commissioned. A number of modifications and improvements were made over the last three years which allowed the gravity circuit to keep pace with the higher tonnage, these are discussed in detail in the body of this paper. The overall approach to gravity concentration at Montana Tunnels has always been to optimize production rather than maximize the gold ounces produced. This philosophy has now yielded a circuit expansion and relocation project which will allow for an estimated 50% increase in gravity gold production, while reducing the overall unit costs of production significantly. This paper will review historical gravity circuit performance, improvements, and the current relocation and expansion project.

Jan 1, 1995

By L. Bomvisinho

As a result of today?s requirements for larger mills with higher power demand, and in order to cope with maximizing throughput, and optimize grinding efficiency, the minerals industry is increasingly relying on the robust Gearless Mill Drive (GMD) solution. This paper describes the new features introduced with the revolutionary ABB drive controller for Gearless Mills, and explains the benefits this can bring to the operation. Extensive surveys have been performed with GMD users to gather suggestions and understand the market wishes. As a result the new driver controller capabilities and functionalities focus on safety, high availability, operational flexibility and remote diagnostics.

Jan 1, 2010

By H. W. Judges

A 16.5-kt/day underground molybdenum mine is being developed at Questa in Northern New Mexico by Molycorp, Inc., a wholly-owned subsidiary of Union Oil Company of California. Construction of the underground mine began in 1979, and first production is scheduled for early 1983. A gravity block caving method has been selected for mining the ore. Access to the mine will be through a service shaft, development shaft, and a conveyor decline. The shafts are being sunk under contract and the conveyor decline is being driven by Molycorp. The driving of the decline began in February, 1979 with a 10-man mining class. By the first of May, enough men had been trained to begin a continuous operation and by March 1, 1980 the face had reached the 1500 m mark. The heading is being driven with trackless rubber-tired equipment using a three-boom drill jumbo, 2.7 m3 LHD units and 7.3 m3 trucks. Ground support has been by rock bolts and wire mesh, followed by Fibercrete. A 16.5-kt/d underground molybdenum mine is being developed at Questa in northern New Mexico by Molycorp, Inc., a wholly-owned subsidiary of Union Oil Company of California. The new $200-million underground project will revitalize mining and milling activity at Questa, where small scale underground mining first began in 1920. Large scale open-pit mining was initiated in 1965 but now, because of the high stripping ratio, surface mining is being phased out. Construction of the underground mine began in 1979, and first production is scheduled for early 1983. The company expects full capacity - 9 Gg of molybdenum per year - to be reached in 1984.

Jan 1, 1980

By J. M. Ekenes, C. A. Caro

"New approaches that increase hydrometallurgical recovery from refractory minerals in below mill cutoff -grade sulfide copper ore can add significant value, improve profitability and increase ore reserves. This paper describes the development and implementation of an engineered heap (EH) approach to leaching low-grade, chalcopyritebearing ore at Freeport-McMoRan’s mine in Morenci, AZ. The technical evolution of the engineered heap concept is described together with the challenges and benefits following implementation. Introduction The Morenci ore deposit, located in eastern Arizona, has been mined for copper for 140 years. Mineralization in the Morenci district consists of sulfides and oxides. To process these ores, Morenci operates concentrator and leaching circuits. Leaching accounts for two-thirds of the copper produced in Morenci. More than one-half of this leaching-derived copper production comes from run-of-mine (ROM) stockpiles. The largest category of material moved in Morenci is destined for ROM stockpiles and waste dumps. Materials that are not economic to mill or leach are designated “waste.” However, this designation can change based on improvements in extraction technology and commodity prices. Chalcopyrite does not leach well due to its refractory nature. For predominant chalcopyrite mineralized ore, copper recovery during a typical leaching cycle may be as low as 5%. For this reason, chalcopyritedominant ores below mill cutoff grade have historically been classified as waste. By incorporating advanced leaching technology to improve metal recovery from previously leach-resistant ore types such as chalcopyrite, the Morenci Mine has been able to reclassify substantial amounts of this “waste” to “ore.” Process chemistry Chalcopyrite copper extraction is temperature, oxygen and ferric dependent. The temperature is achieved primarily by pyrite oxidation (Eq. (1)) and secondarily by oxidation of chalcopyrite itself (Eq. (2)). The regeneration of ferric in solution can be enhanced by providing the appropriate acid and oxygen levels according to Eq. (3). In the absence of microorganisms, this reaction is very slow."

Jan 1, 2015

By G. Guzman, L. Sevilla, M. Botz

"Newmont Mining Corporation operates the Yanacocha mine in Perú and the gold milling section of the property includes a Sulfidization-Acidification-Recycle-Thickening (SART) plant to remove copper from pregnant leach solution. Since its commissioning in 2008, the plant has been intermittently operated as needed to remove copper upstream of a carbon adsorption circuit. However, starting in 2015 Newmont expects the plant to operate on a more continuous basis in response to higher copper ores that will be processed in the gold mill. In anticipation of this, Newmont conducted a campaign in May 2014 with stockpiled high-copper ore to evaluate performance of the SART plant with elevated levels of copper in feed solution. Results from the campaign demonstrated the SART plant is capable of efficiently treating high-copper leach solution. During the campaign, leach solution copper levels ranged from about 100 to 700 mg/L, and copper removals ranging from about 56% to +99% were achieved. The median copper removal efficiency observed during the campaign was about 94%. The primary plant modification determined necessary following the campaign was the need to improve consistency with sulfide dosing. INTRODUCTION Copper removal from cyanide leach solution can be affected through the addition of sulfide at acidic pH to precipitate copper sulfide as a solid. There has been renewed interest in the process in the past several years due to the increasingly common issue of high copper levels in cyanide leach solutions. The term Sulfidization- Acidification-Recycle-Thickening (SART) is used as an acronym for the process according to the primary unit operations utilized. At a pH of approximately 4.0 to 5.0, the addition of soluble sulfide to a copper-bearing leach solution will result in the precipitation of copper sulfide (Cu2S) solid. The overall acidification and sulfidization reaction is (assuming the use of sulfuric acid for pH adjustment): 2Cu(CN)3-2 + 3H2SO4 + S-2 ? Cu2S(s) + 6HCN(aq) + 3SO4-2 The above reaction is written relative to the copper-cyanide complex 2Cu(CN)3-2, though analogous reactions also take place with the other common copper-cyanide complexes Cu(CN)2- and Cu(CN)4-3. Sulfide in the above reaction (S-2) is normally supplied as sodium hydrosulfide (NaHS) purchased in solid or concentrated liquid form. Two characteristics of this reaction that are beneficial to a leaching operation are: 1. Copper is removed from solution as Cu2S (synthetic chalcocite) solid, which can then be sold to a smelter for its copper value. 2. Cyanide that is complexed with copper in the leach solution is released as free cyanide, thereby regenerating cyanide that can be recycled to the leaching operation for continued use."

Jan 1, 2015

By C. Waddell

PDMI mines five different grades of ore. Shovel operators were experiencing problems differentiating one material type from another. In 1997 PDMI decided to try GPS ore control to aid operators in identifying material boundaries. Computer generated ore control maps and GPS data defining the shovels' position is fed to a computer on board the shovel. A monitor, located near the shovel operator, displays material types, their boundaries, and the shovels' position and movement in relation to the mining face. This information has reduced errors in material identification by 50%.

Jan 1, 1998

By R. K. Mehta

Existing acid mine drainage treatment techniques are not remedial In nature, i.e. though heavy metals can be removed from acid mine water, their presence in tailings and large quantities of these tailings tend to increase capital and operating cost for tailing management. This paper presents the results of a series of systematic tests which finally resulted In the development of the "ferrite" process for mine drainage of coal operations at ambient temperature. The role of pH, temperature, quantity of ferrous salt addition and degree of oxidation is investigated targeting the production of high emu spinel ferrites and effluent water complying regulatory standards with respect to Iron. manganese suspended solids and pH.

Jan 1, 1992

By Fabiola Espinoza Carmona, Elena Chiriotti, Edoardo Misano

"INTRODUCTION Ganntas Tunnel is part of the modernization project of the railway between Alger and Oran, in Algeria. In order to double and rectify the existing line between El Affroun and Khémis Miliana, the alignment foresees the excavation of a 7 km-long twin tunnel. The excavation works started in June 2011 with the contractor CCECC, under the supervision of SYSTRA. Excavation is driven in conventional method by hydraulic hammer simultaneously on 8 different faces since excavation was started also from a junction window towards the middle of the tunnel. The minimum longitudinal distance to be respected between two contiguous tunnel faces has been set to 30 m. The tunnel cross-section is a 70 m² oval shaped profile, temporary support consists of shotcrete, bolts and steel ribs. A 30 to 50 cm thick cast in situ concrete final lining has been provided as well. When the tunnel reached a fault zone in soft clayey marls extreme squeezing occurred, works were stopped and re-profiling operations were carried out along more than 100 m. To date, works proceed at slow rate since high convergences are still monitored and completion of works is not expected before December 2016.GEOLOGY The project is located within the Tellian Atlas mountain area, including in particular the Djebel Ganntas massif in between Mitidja and Chleff plains. Djebel Ganntas is characterized by an extensive massif aligned in East-West direction with smooth slopes made of soft clays that emerge in multiple cliffs and ravines. On the top of it, along the edge, a more recent sandstone formation is found. The existing data on the geology did not allow to establish an accurate geological model at tender stage. In-situ investigations allowed at design stage to identify a Quaternary alluvial cover of clays and gravel, followed by a Miocene stratum divided in a sandy top layer and a lower clayey layer. From a structural point of view, geological maps suggest a north direction dip of layers, but the in situ surveys showed that layers were highly folded. The lack of information at tender stage on the structure of the geological series should have triggered an extensive investigation campaign at detailed design stage which did not take place causing serious consequences on costs and time at construction stage."

Jan 1, 2016

By Alessandro Boscaro, Daniele Martinelli, Cristina Gabriela Oñate Salazar, Daniele Peila, Carmine Todaro

"The wear phenomenon in TBM machines is not a simple issue, as many parameters are playing an important role on the consumption of the tools during a tunnel excavation. The action of the wear due to the contact with the soil can occur on the excavation tools, on the cutterhead, in the excavating chamber and on the screw conveyor. The test developed at the Laboratory “Tunnelling and Underground Space Center” of the Politecnico di Torino is aimed to reproduce the interaction between the tools and the excavated material, simulating the excavation conditions in terms of soil conditioning and water content. The test, which is not standardized, is studied to evaluate the wear in a global point of view. The present work starts by testing the influence of the use of chemical agents during the conditioning phase on the drop of the wear phenomenon, in terms of metal weight loss. 1. INTRODUCTION The wear phenomenon of the excavation tools used in TBM tunneling machines is playing recently a major role in the design stage of full-section tunnels in both soils and rocks. Concerning EPB excavation technology, the main issue regarding productivity is the wear of its components (Peila et al.,2012), which increases the so called dead time in the whole process. The friction generated between the components and the ground causes the consumption of the tools and other metallic components in contact with the ground, described as primary and secondary wear by Nielsen et al. (2006a). This leads to downtime, with risky and complicated maintenance operations (Peila and Schulkins, 2009), as occurred in recent tunneling works in Liguria (Italy). The study of this argument in granular soils is very delicate, as it encloses not only the properties of the excavation tools, but also the characteristics of the ground to be excavated (hardness, mineralogy composition, shape and dimension of the particles and moisture content). The penetration mechanism is based on the scraping of the ground, by mean of cutting tools, with its consequent consumption. Concerning the rocks, the excavation principle is characterized by crushing the rock mass matrix by applying high compressive stresses through cutting disks. In such a way, to avoid frequent downtimes and their consequent economic losses, it is very important to study this subject and therefore understand and forecast the durability of the components, in order to try to maximize the productivity of the machine by reducing the frequency of maintenance stoppings."

Jan 1, 2016

By Jr. Matthews

The Candelaria copper-gold deposit is located in Region m of Chile, 805 kilometers north of the capital, Santiago. Candelaria was discovered in 1987, following a six month exploration program. In late 1986, induced polarization (IP) surveys outlined an anomalously high response within the area of interest. The first test hole bad three intersections totaling 49 meters, with an average grade of 1.97% copper. Drilling eventually outlined approximately 390 million tonnes, grading 1.09010 copper and 0.26 grams/tonne gold. Production began in early 1995 and is estimated at 120,000 tonnes copper and 80,000 ounces gold annually.

Jan 1, 1996

Several major impediments threaten the successful delivery of tunnel and under-ground construction projects. In addition to technical design and construction risks associated with tunnel projects, many of which are well understood, budgetary pressures, funding constraints and the complexity of procuring, administering and executing multiple concur-rent projects in a large program could also have a catastrophic impact on the program?s objectives. Contributing factors often include poorly managed design, procurement, construction, managerial, organizational, market and stake-holder risks, as well as nonconforming inputs or outputs to the costs and schedule, or any other potential inabilities to deliver the required or desired results. A strategy to prevent ?failure? of a project requires a proactive and holistic approach to risk management. Through planning, identification, analysis, management, monitoring and control of the project?s risks (both threats and opportunities), attention to management of risk will in-crease the probability and impact of positive events and decrease the probability and impact of events adverse to a project?s objectives.

By G. E. Maryniak

To date, human space exploration has been almost completely dependent on the use of resources carried with astronauts and cosmonauts from the surface of the Earth. The only exception to this has been the harvesting of solar energy to power space stations like Skylab, Salyut and Mir for long-duration missions. This dependence on materials which must be transported into orbit at costs in excess of $5000 per pound is the fundamental limiting factor in space exploration and operations. It is likely that launch costs can eventually be greatly reduced by means of such innovations as true single stage to orbit vehicles, aerospace planes, or serial electromagnetic or laser launch systems. However, the Earth will always remain an expensive source of materials for space construction and for basic commodities such as propellant and life support liquids and gasses. Fortunately, abundant sources of materials exist which are already in space, outside of the Earth's deep gravity well.

Jan 1, 1992

By T. G. Hayes

Economic and environmental regulations in the coal industry have required companies to evaluate their current blasting method of loosening in-situ coal. This paper will review ripping vs. blasting thick in-situ coal seams, handling frozen active coal stockpiles and proper stockpile conditioning and reclaiming. How basic operating technique can improve job efficiency, productivity and cost per ton.

Jan 1, 1995

By S. Jennings

The Red Dog massive sulfide deposit is located in the western Brooks Range of Alaska 100 miles north of the village of Kotzebue. It contains the largest zinc reserve in the world. Reserves were doubled in 1995 with the discovery of the Aqqaluk deposit and significantly increased in 1996, with the discovery of a deep zone of mineralization to the north. At present the global reserve and resource is 143 million tonnes of 16.1 % zinc and 4.3% lead. Red Dog is a silica + sulfide synsedimentary replacement deposit hosted in barite and black shale of the Mississippian Kuna Formation. Red Dog was thrust northward during the late Mesozoic Brookian orogeny. Understanding the setting of the deposit at the time of formation and its subsequent deformation history is critical to current exploration efforts and to future discoveries in the district.

Jan 1, 1998

By QU Hong-lue, YANG Lin-han

Aiming at the subjective impact caused by subjective weighting method in the establishment of rockburst risk attribute identification and prediction model, the combined weighting method was introduced to eliminate the influence of unreasonable weight of each index. Eight discriminant indexes affecting the risk of rockburst were selected. Through the literature review, relevant rockburst cases were collected and 8 index rockburst sample sets were established. A variety of machine learning methods were used to analyze the feature importance of discriminant indexes in the samples, and then to determine the objective weight values of different methods. Combined with the subjective weights determined by the Analytic Hierarchy Process, the combination of weights were successively carried out. Based on the attribute recognition theory, the combination weights with different objective weight methods were established to identify the rockburst risk attributes, and verified by the confidence criterion. The results show that the objective weight value determined by the feature importance analysis of machine learning reduces the subjectivity of the weight of Analytic Hierarchy Process method, improves the prediction accuracy, and makes the prediction result closer to the fact.

Apr 26, 2022

By F. Warnaars

Historically, this area produced gold and silver from many well-known vein deposits, like Tayoltita, Topia, and San Jose de Gracia. Modern exploration identified three categories of deposits: 1) low grade porphyry golds in shallow level dacite porphyries; 2) batholith-related deposits; and 3) those formed in volcanic sequences of Late Cretaceous to Late Tertiary. At least four porphyry golds have been identified, of which Metates is best known. These are formed by and within dacite porphyries, associated hydrothermal breccias and sometimes within surrounding metasediments. Their ages are from mid-Cretaceous to Early Tertiary. Precious metal deposits associated with batholiths occur as veins, contact haloes in metasediments or volcanics, skarns, tectonic breccias, hydrothermal tourmaline breccias, dacite dikes or as disseminated or stockwork deposits such as La Fortuna. Several new gold discoveries were made in older Early Tertiary Volcanic Sequences and in the younger Tertiary volcanics within prominent structures exceeding 3 to 5 km in lengths. Some of these are open-pittable but most have to be mined by underground methods.

Jan 1, 1999

By Plato Malozemoff

While this conference is dedicated to the examination of "Challenges in Mineral Processing," the broader aspect of the pursuit of this subject is Research and Development in the Mining Industry. When I was asked to speak at this symposium, I hesitated to accept. While my early schooling, training and professional occupation were in the field of this symposium, it was so long ago that I no longer feel competent to contribute anything of interest to you except perhaps for a limited historical perspective, which most of you probably already know. However, it might be worthwhile to explore the more general aspect of research and development from the viewpoint of management, as this is the stance from which I dealt with the subject for the last 30 years or so. While most managements generally have a positive view of research and development, few of the leaders in the mineral industry have actually had the personal experience of doing research for a long enough time to have obtained a full understanding and the feel for its place in the long-term technological innovation that our industry must foster. I graduated from the University of California in Berkeley with a Bachelor of Science degree and a major in metallurgy. It was during the great depression of the thirties, and it was difficult to obtain a practical job in the industry. I got a scholarship at the Montana School of Mines and received a Master of Science degree in ore dressing under Professor A. M. Gaudin, followed by another year with him pursuing research. Anyone who studied under him, or knew him well, would assert that this was a unique experience. Gaudin had a brilliant mind and a profound respect for science and the scientific method. He wished to know the scientific basis for every new technological appli-

Jan 1, 1989

By J. M. Hird

By blending phosphogypsum with thickened mill clays, Texasgulf has successfully resolved the problems of gypsum disposal and reclamation of mined-over areas. In the process, clays are thickened to 10% solids through high rate thickeners, mixed with gypsum from a drained gypsum pile (75%) and a direct discharge from belt filters (25%), then pumped to mined-over areas. The blending of clays and the low pH gypsum yield a mixture with a pH of about 7. Dewatering is rapid to 40-45% solids within 3 months. The material spreads with very shallow slopes and within a year desiccation by high flotation ditching equipment is possible. The artificial soil is classified as a silty loam in texture, lacking only in nitrogenous nutrients. The soil material has proven to support many field crops including small grain, corn, alfalfa, and grasses. Sycamore, green ash, sweetgum and bald cypress have done well in 3 years of growth. The nitrogen source for tree growth will be made up through an alfalfa cover.

Jan 1, 1993

By Georgi N. Shoushoulov, Ventsislav D. Bozhilov

The mining conditions in the Meden Rid mine at levels below 1000 m from the Earth's surface are specific and rather severe. The rock temperature is about 40-45°C. The air humidity in the workings is approx. 80-90%. There is a limited capacity for additional fresh air supply. The air supply and distribution systems in the mine are very complicated. The airflow recirculation is due to the existing arrangement of the main fans. Certain accidental phenomena are difficult to predict. All these conditions create possibilities for heat and mass exchange between the rock and the air current thus hampering the control of the ventilation and air-conditioning in the mine workings. The changes in the temperature and humidity in certain characteristic places of the development and extraction workings are predicted. The refrigeration output required and the arrangement of the air coolers are also determined. A new ventilation and air- conditioning scherne has been developed. The new ventilation- cooling designs for levels between 1000-1200 m beneath the Earth's surface are based on the use of portable refrigerating machines having low water flowrate as well as heat-insulating and waterproof materials and methods for preliminary cooling of the orebody within the mining block.

Jan 1, 1997