Search Documents

By M. Bennett, L. Twidwell

Montana Tech has embarked on a coordinated series of studies to delineate the characteristics of the Berkeley Pitlake containing over 36 billion gallons of acidic, metal-contaminated water formed after the cessation of open-pit copper mining in Butte, Montana, USA. The objectives of the overall series of studies are to summarize presently available information and to generate new and needed information to formulate a conceptual environmental model for the pitlake and to provide characterization data for the development of advanced treatment technologies. In this presentation, the chemistry of the Berkeley Pitlake water is partially reviewed. It is known that the pitlake consists of two distinct layers of water referred to as surface and deep water. Samples of deep water were collected and placed in a 12-ft high and 6-inch diameter column and exposed to different wavelengths of UV radiation as well as atmospheric conditions. Measurements of pH, redox potential (EH), dissolved O2, turbidity, conductivity, temperature, and elemental composition show that the water reacts differently and indicates that the diurnal effects of sunlight likely play a major non-biological role in its chemistry. Resulting technology could be useful for developing an alternative to treating acid-rock drainage.

Jan 1, 2007

By P. Jurovcik, D. Yantek, D. Ingram

The National Institute for Occupational Safety and Health (NIOSH) identified hearing loss as the most common job-related disease in the United States in its 1996 National Occupational Research Agenda. Previous studies by NIOSH have shown operators of surface drill rigs without cabs are commonly exposed to A-weighted sound levels exceeding 90 dB. During hammer-drilling, A-weighted sound levels exceeding 100 dB were recorded at the operator station. NIOSH collaborated with a local drilling company to design and install a partial cab between the operator and the drill steel in an effort to reduce the sound level at the operator station. Sound level measurements in the field show the partial cab reduces the A-weighted sound level by 5-9 dB at the operator’s left ear and 2-5 dB at the operator’s right ear while hammer-drilling. This paper will briefly discuss the preliminary design of a cab and the testing of materials for construction of the prototype. Explanation of the ideas behind the prototype design and fabrication will be covered. Finally, the field test method and results will be discussed in detail.

Jan 1, 2007

By D. Govender

In recent years, economies of scale have continued to drive copper projects to larger throughputs to offset depleting lower grade resources. A decade ago there were only a small number of projects that stretched beyond 100,000 Mtpd throughput rates. Nowadays and moving forward virtually all the major copper projects are sized beyond this, with throughput rates up to 250,000 Mtpd now under evaluation for a number of key projects in Chile and Peru. This paper explores the development from the 160 m3 flotation cells, through to the 257 m3 cells and nowadays to the 660 m3 machines. The contributions of specific copper concentrators to this growth phase are reviewed herein. The historical basis of flotation machine scale-up is also briefly discussed. Metallurgical results as well as layout, maintenance and operational aspects are highlighted.

Feb 27, 2013

By G. H. Sedahmed, S. A. Nosier, M. H. Abdel-Aziz, A. A. Mubarak, M. A. El-Naggar, E. G. Abdel-Aziz

The performance of a rotating fixed bed reactor in recovering copper from industrial waste solutions by cementation is studied under various conditions. The rotating fixed bed is made of stacked woven steel screens to take advantage of two features of screens: the ability to present large area per unit volume and their ability to promote high turbulence. Variables studied are initial CuSO4 concentration, bed rotation speed, mesh number of the screens and bed thickness. The presence of baffles was found to increase the rate of cementation. The data were correlated by a dimensionless mass transfer correlation suitable for the design and operation of large scale cementation reactors.

By G. H. Sedahmed, S. A. Nosier, M. H. Abdel-Aziz, A. A. Mubarak, M. A. El-Naggar, E. G. Abdel-Aziz

The performance of a rotating fixed bed reactor in recovering copper from industrial waste solutions by cementation is studied under various conditions. The rotating fixed bed is made of stacked woven steel screens to take advantage of two features of screens: the ability to present large area per unit volume and their ability to promote high turbulence. Variables studied are initial CuSO4 concentration, bed rotation speed, mesh number of the screens and bed thickness. The presence of baffles was found to increase the rate of cementation. The data were correlated by a dimensionless mass transfer correlation suitable for the design and operation of large scale cementation reactors.

By David Caiden, Geoffrey Fosbrook, Jaidev Sankar, Donald Phillips, Jon Hurt, Anil Parikh

This paper will cover the progress being made on Phase 1 of New York’s Second Avenue Subway line. It will include a description of construction progress on the first contract to be let, which consists of a 248 m (815 ft) long launch box, 3.9 km(2.4 miles) of TBM tunnels and a tunnel sump; the packaging strategy for the remaining work; and the progress through Final Design of the remaining packages, including the two large span rock cavern stations.

Jan 1, 2007

By Patrick J. Doig

The contract for the construction of the Inline Pump Station for the Milwaukee Metropolitan Sewerage District involves the sinking of three shafts and the excavation of a pump chamber. The shafts are being sunk to a depth of 104 meters and pass through 52m of sediments before encountering dolomitic bedrock. The pump chamber is constructed in dolomite. The sediments are alluvial, estuarine and lacustrine in origin, with some ice margin deposits. They comprise loosely consolidated fine to coarse grained sand, silts, clays and gravels, and they are heavily saturated with a water content often above 60%. The water table is at a depth of 3m. The dolomite is silurian, generally dense, with some clay-filled vugs and shale partings. Until 1983, underground construction in the Milwaukee area had been limited to depths of 26m in the sediments and 20m in the dolomites. Water control methods had included caissons, compressed air, extensive internal and external dewatering, and grouting. Flows of 20 liters per second were commonplace with as much as 80 liters per second being encountered in the rock. However, in 1984 work was commenced on the deep sections of the Milwaukee sewerage scheme with the letting of three major contracts including the Inline Pump Station. With excavation taking place at greater depths, it become obvious that previous methods of water control would be inappropriate. To protect against major inrushes of high pressure water in the rock, an extensive program of pre-grouting from the surface was specified. Water control in the sediments was left to the discretion of the contractor and in each case freezing was choosen. This paper describes in detail the grouting and freezing procedures.

Jan 1, 1985

By Richard Kastner, Emilie Vanoudheusden, Fabrice Emeriault, Jacques Robert

INTRODUCTION The subway line B of Toulouse (France) has been realized with three different tunnel boring machines (TBM) techniques: Contracts 2 and 5 are excavated with earth-pressure balanced TBM, Contract 4 with a slurry shield TBM, and Contract 3 with a compressed-air TBM. The first three machines are around 7.7 m in diameter, while the last one is 5.3 m. Moreover, a small part of the line (50 m) has been excavated by a conventional method. The tunnels run through the Toulouse molasses, composed of hard sandy clay with pockets and lenses of dense sand. Geotechnical investigations have shown that in these formations, K0 is greater than 1, around 1.8 at a depth of 25 m (Serratrice,2005) and that geotechnical characteristics are homogenous on the whole layout (? =22 kN/m3, Su = 300 kPa, c' = 30 kPa, F' = 32°). The water table is found between 2 and4 m below ground level. As geology, stratigraphy and tunnel cover (between 10 and 20 m) are almost identical, a comparison of movements induced by the excavation by each of the four excavation techniques is possible. This paper presents the soil mass movement measures in the case of the conventional excavation method and in the case of TBM sections. It shows how tunneling parameters may explain the different surface movements observed during excavation. For the sake of simplicity, only the results of Contract 2 (earth pressure balanced TBM)will be presented. MONITORING Monitoring for the Conventional Method Section For the conventional method section (Vanoudheusden et al. 2005) the mass soil movements are measured with two inclinometers and one multi-point extensometer borehole with automatic data acquisition (Figure 1). The monitoring devices include

Jan 1, 2007

By Alfred Weiss

Selecting a minicomputer is not unlike selecting a costly piece of mining equipment such as a truck, shovel, crusher, or conveyor belt system. A marked difference might lie in the frequency at which such selection takes place; another difference might be mine management's familiarity with mining equipment vis a vis a minicomputer. These basic differences might prompt a mining company to seek the aid of a consultant when selecting a minicomputer system. Advantages and Disadvantages The fundamental advantage of employing an independent consultant is that it provides management with a source of knowledge and breadth of experience not readily available within the organization. If the consultant has a minerals background, such knowledge and experience are further enhanced by actual experience in exploration, mining, and mineral processing. If the consultant has worked within a mining company, such hands-on experience is supplemented with a meaningful understanding of the client's business; this facilitates communication between the consultant and members of the client organization. The consultant has been, so to speak, "in the client's shoes." There are several other advantages. Since computer systems cut across organizational boundaries, the independent consultant may be able to move within the organization more easily than an inside staff person to collect necessary information. Also, detachment from any manufacturer should provide the client with an objectivity and a set of recommendations as near optimal as feasible. The principal disadvantages lie in the area of continuity and accountability. Once the consultant's report has been submitted and his recommendations implemented, a discontinuity might occur. Also, if implementation does not provide the desired results, the consultant might not be available to correct the situation or account for actions taken. Proper selection of consultant services, relative to kind and duration, and the consultant's method of operation, will often prevent many of these aftereffects. Services Offered The professional consultant can help a client: •Define and summarize information systems technology* needs; • Evaluate alternatives such as in-house capability and capacity, time-sharing, or service bureaus; • Prepare a formal request for proposal (RFP) to be submitted to vendors; •Evaluate vendor proposals; •Evaluate the economics of lease vs. purchase; and •Assist in the conversion and installation. Thus, consulting services may range from evaluating an existing system and upgrading to a larger piece of equipment, to selecting a new first-for-the-organization computer. First, Define and Summarize Needs Regardless of circumstances, the most valuable document required before equipment selection is the information system plan (I/S plan). It helps insure that the company's information needs are met in a cost-effective manner. An I/S plan is usually a comporient of the mining company's overall business goals. Since an I/S plan is a formal vehicle for establishing and communicating the direction the organization intends to take to satisfy information requirements needed to achieve goals and objectives, most initial systems services are likely to center around creating such a document or updating an existing document. The trend toward company-wide I/S planning is increasing in the mining industry; however, smaller scale efforts focused at the information systems needs to support an individual

Jan 11, 1981

By William M. Gleason

When SME’s 2006 Arizona Conference convened in December at the Hilton El Conquistador Resort in Tucson, AZ, there was considerable excitement among the 387 attendees. There was a noticeable buzz surrounding the progress of Phelps Dodge’s Safford copper mine in southern Arizona, one of the first new major copper mines to be permitted in more than 30 years in the United States. There were also plenty of good feelings about the mining industry in general. Commodity prices remained high and with no signs of a slowdown in the immediate future. Things were good in Arizona. But there were also cautionary tones at the conference and the Mining Foundation of the Southwest banquet that preceded it.

Jan 1, 2007

By Chikaosa Tanimoto

INTRODUCTION Bratislava is located at the intersection of important traffic routes, including motor-ways, roads, railways, air traffic, trading, and inland waterway with an important harbour. The construction of the D2 Motorway Bratislava, Lamacska cesta Stare grunty was the last missing section of D2 Motorway and its completion linked the Czech Republic through Bratislava to the Hungarian Republic. Traffic was obliged until its completion to use the Lamacska Road and Mlynska Dolina, which were the most heavily trafficked roads in the city. The section of D2 Motorway to be completed in 2006 was 3,300m in length, of which the SITINA Tunnel was approximately half the length. After putting into operation the transit traffic(motorway) and urban traffic was separated. Transit traffic by passing the town was eased. The junctions D2 with Lamacska Road (Harmincova) and Mlynska Dolina also allowed better use of the motorway for the urban traffic The tunnel construction was specified by the features with the highly weathered and thermally altered granitic rock formation with the overburden of Quaternary sediment of 2?4 m thick, very thin overburden, severely controlled deformation limit and environmental protection. The tunnel had to be excavated beneath and nearby the academic complex area and the zoo, where sensitive facilities exist and animals live in. The tunnel consisted of two tunnels (Tunnel A and B) with the length of 1,415 and 1,440 m, respectively. The overburden thickness was in the range from 10?30 m. The standard cross-section and the one with invert arch were 79.5?81.5 m2 and 92.1?93.3 m2. The excavation took 21 months from September 2003 to May 2005. The construction was based on the concept of NATM. The SITINA Tunnel was the third application of NATM in Slovakia, following the BRANKISKO Tunnel (commenced in July 2003) as the first and the HORELICA Tunnel (in October 2004) as the second NATM practice. To protect the surrounding structures and citizens from tunneling operations, seismic monitoring was performed in association with blasting. The allowable limit of blasting vibration was fixed to be under the particle velocity of 15 mm/sec. The tunnel excavation cleared this limit as expected before construction. In driving through the difficult geological situation the excavation work hit 49 faults, and some of them occasionally caused serious face instability. In principle, the rock formation has been affected by the high hydrothermal effect and the resultant clay filing along faults and joints. The auxiliary reinforcement with the 4?8 m long pipe roofing was needed to protect the vicinity of mining face area. This operation extraordinarily required additional works and time which had not been expected before construction.

By Murat Erdemoğlu, Turan Uysal, Thierno Saidou Barry, Mustafa Birinci

The rapid development of the global alumina and aluminum industry is straight coupled with the demands and the needs of these materials. Nowadays, the only well-known accessible resources to produce alumina and aluminum are bauxite ores. But bauxite ores are limited, and the remaining exploitable reserves do not have high contents in alumina. In countries where there is little or no bauxite reserves or where the recovery of existing bauxite ores to produce alumina with the Bayer process are not economic, alternative resources for alumina have been explored. The most attractive resources for replacing bauxites are aluminosilicate clay minerals and coal fly ash. The important processes developed for the recovery of alumina from these sources are acid leaching and alkaline leaching processes. The acid leaching is known as the most efficient in which thermal and mechanical activation are included for improving the performance of the process. The objective of this review is to give a comprehensive insight on the production of the alumina from thermally or mechanically activated clays and coal fly ash by hydrochloric, sulfuric, and nitric acid leaching processes.

By Antonio Pineda, Roger K. McLimans, Felicity E. Lloyd

lmenite is a primary ore feed to the DuPont chloride process for the manufacture of titanium diox-ide pigment. We seek to determine ilmenite geochemistry as a function of original source and as-certain which ilmenites have chemistry most amenable to upgrading via iron-leaching (leucoxenization) and that have favorable, with respect to pigment manufacture, trace element content. Ilmenite geochemistry is a function of its primary origin and of subsequent alteration. Heavy mineral sand deposits may contain ilmenite from one or several dominant source rock(s). In addition, ilmenite may alter in the weathering environment, changing the major element compo-sition (iron-leaching) and certain of the minor element content. A primary objective is to classify ilmenites in relation to origin in order to fingerprint source rocks in provenance determination. The changes in trace element chemistry during alteration are also investigated. A “decision tree” is developed to classify ilmenite types and source rock origins. Ultimately, with those methods and by amassing a database of ilmenite types from worldwide locations, it should prove possible to determine ilmenites (and their sources) more susceptible to iron leaching in the weathering en-vironment. Such ilmenites, enhanced in their titanium content, are the preferred ore targets. The method used is electron microprobe analyses at elevated conditions of voltage, cur-rent, and counting time to enable higher precision. In-situ ilmenites from igneous, metamorphic, and altered rocks (saprolites) are analyzed. Initial foci for sedimentary ilmenites are restricted provenance (approaching monogenetic, examples from Spain, Portugal) and polygenetic prove-nance (Denmark). Altered ilmenites, including the DuPont Florida ore, are used to characterize the chemistry of leucoxenization. Trace element concentration, detectability, and cost considera-tion, led to focus on Mn, Mg, V, Cr, and Nb to develop a classification scheme validated by dis-criminant analysis and “classification-regression trees”. Results show a high degree of success for restricted provenance study and an acceptable one for polygenetic provenance.

Jan 1, 2005

By A. Noble

Traditional simulations of mineral processing circuits are solved by straightforward numerical techniques which require iteration to accommodate recirculating loads. Depending on the complexity of the simulated circuit, this solution technique can be inexact, computationally intensive, and potentially unstable. In this communication, an alternate calculation approach is presented, wherein an exact analytical solution is determined as a function of the individual units? separation probabilities. All the stream data, including recirculating loads, may be solved simultaneously, negating the need for iteration. Furthermore, with an analytical solution available, circuit analysis may then be utilized to diagnose the relative separation potential of the circuit. By integrating these tools, the authors have developed a software package for evaluating circuit configurations. This paper presents the theory, development, and limitations of the software?s methodology along with industrial examples which highlight the tool?s applicability to industrial circuits.

Jan 1, 2012

By Frederick A. Mumpton

Recent findings by medical workers on the association of certain zeolite minerals with the high incidence of pleural mesothelioma in two small Turkish villages have caused considerable excitement both in medical circles and in the synthetic and natural zeolite businesses. The 42 cases diagnosed between 1970 and 1977 in one community of 600 population in a region of altered volcanic tuff represent a virtual epidemic of this rare malignancy which normally strikes only about one person in a million. Cancer workers around the world expect that detailed environmental and epidemiological studies of the disease in these areas will shed considerable light on the cause of this particularly lethal form of lung cancer. Scientists and engineers developing uses for zeolite materials in industry and agriculture, however, are justly concerned that the preliminary results available on this situation will be used by environmental and regulatory organizations to label an entire group of miner- als as carcinogens on the basis of what is little more than circumstantial evidence. Although there is no question as to the large number of cases of mesothelioma in these areas of central Anatolia, the work to date has suffered from a lack of sound geological and mineralogical input. Ataman (1) stated that a "correlation" exists between mesothelioma and zeolites in this region; however, the geological data needed to document a direct relationship between the presence of zeolites in the volcanic tuffs surrounding the villages in question and the rate of malignant lung disease in the inhabitants have g been obtained, nor has evidence that suggests a cause-effect relationship between zeolites and cancer been reported. To provide fundamental information on the distribution of zeolite minerals in areas of central Turkey where high incidences of pleural mesothelioma have been reported and to evaluate from first-hand knowledge the published reports and news releases of medical workers engaged in assessing the problem, the following investigation was made.

Jan 1, 1979

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

If one can embrace the medical analogue, much of the mining industry currently suffers from a massive bacterial infection. When pyrite-bearing or sulfide-bearing rock formations, tailings, or mine wastes are infected by Acidithiobacillus ferro-oxidans, the likelihood of forming acid rock drainage (ARD) is almost guaranteed. The ?pharmacy? of antibiotics available is extensive, ranging from solid alkaline amendments like limestone to liquid ?medicines? such as sodium lauryl sulfate, sodium thiocyanate, waste milk, and bipolar lipids. Unfortunately, the ?geo-medical? teams of geochemists, microbiologists, engineers, and mine managers lack the tools to surgically apply these active ingredients where they are needed most with a minimum of waste. Distribution of fine grained limestone on the surface of an acidic mine waste dump is analogous to applying a bandage soaked in antacid to treat an upset stomach. The implementation of up-to-date best management practices has not healed the patient; an equivalent combination of hypodermic needle, cyber knife, and arthroscopic probe is clearly needed. Using an engineered, flow-able or pumpable foam or pHoam? as the medicinally analogous ?dextrose delivery solution? for solid and/or liquid ?geo-antibiotics?, the authors have combined off-the-shelf technologies that have been previously applied in solving geotechnical problems in the mining industry. A patent for the innovative process is pending. This paper discusses method concepts and the advantages it could provide over conventional BMPs.

Jan 1, 2012

By Rolf B. Pedersen, Ana Filipa Marques, Ingunn H. Thorseth, Ingeborg Okland

"Deep sea mining of polymetallic sulphides will change the physical and chemical conditions at the seafloor by creating scars when sulphides are removed, and potentially also by deposition of mine tailings at the seafloor. These changes will impact the existing ecosystems at the seafloor in and around the mined areas. Seafloor Massive Sulphide deposits that have been exposed to oxic seawater weather into Fe-metal-oxyhydroxides. However, the rates of weathering and release of heavy metals and other toxic compounds to the environment from freshly exposed sulphides in a deep-sea environment are not well studied.During a cruise to the Arctic Mid-Ocean Ridge in the Norwegian-Greenland Sea in July 2014 we will initiate in-situ experiments investigating the microbiological and geochemical processes involved in the weathering of freshly exposed massive sulphides deposits in a natural environment. This will be done by creating scars in naturally occurring sulphide deposits and by deploying weathering experiments at the seafloor. The sites will be revisited and re-sampled in 2015. The mobility and fate of heavy metals will be one of the main concerns of the study as well as constraining the time it will take for exposed sulphides to return to the chemical state present prior to mining. In this presentation we will present the experimental framework and the preliminary results from the July 2014 cruise. This project is part of the EU funded MIDAS (Managing impacts of deep sea resource exploitation) project."

Sep 1, 2014

By C. K. Kocsis, S. Hardcastle

Mine ventilation, requires electricity to operate the fans and fossil fuel for heating. Typically, this accounts for approximately 40% of the overall underground energy consumption. This is considerable, and one of the major causes of this expense is that most mine ventilation systems are designed for the "worst-case-scenario" with respect to ventilation demand, which is commonly dictated by diesel equipment usage. Once designed, mines tend to operate their ventilation system at this peak level despite their exceeding day-to-day development and production needs due to lack of appropriate ventilation controls. In underground metal mines, TeleminingTM, which includes the tele-remote operation of mobile development and production equipment from surface, will change the mine design criteria including its support infrastructure such as the ventilation system. With the removal of machine operators to surface control rooms, conventional ventilation systems designed to dilute and remove pollutants can become redundant. Depending on the ultimate need for ventilation, its cost in automated mines with tele-remote equipment operated from surface will be lower than the cost of ventilation in conventional mines. These cost savings, which could be significant, would not only come from the ability to reduce the amount of ventilation in the mine, but also through the capacity to automate its distribution. This paper provides an indication of the new airflow requirements in stopes and dead-end developments for the tele-remote and automated mining processes based on climatic modelling. Furthermore, this paper makes a cost benefit analysis by comparing the ventilation system operating cost of a conventional underground metal mine based on the mobile diesel powered equipment design criteria with the newly redesigned ventilation system operating cost of an automated mine based on the "heat management" design criteria.

Jan 1, 2002

By Andrew B. Cecala, Emily J. Haas, Jay F. Colinet

A sociotechnical system (STS) creates a framework that allows an examination of how social and technical factors affect organizational outcomes within a specific environmental context. STS has been rigorously studied with a primary research focus addressing worker-technology interactions. Although these interactions are important, the social processes and interactions that occur whenever any technical or environmental change is introduced into the system have been undervalued. If social processes are better understood, mining organizations could efficiently prepare and stabilize for such changes. With this goal in mind, we sought to extend STS theory through applying principles of meta-design to analyze the results of two case study interventions. Specifically, we studied the impact of an unregulated dust control technology (the Helmet-CAM) and a regulated dust control technology (the Continuous Personal Dust Monitor) on factors within an STS including employees’ knowledge of, communication about, and use of technology to mitigate respirable dust sources. The results are presented in a way that first, addresses the overarching principles of meta-design STS including organizational participation, flexibility, and communication and second, examines how technology implementation processes differ when the organization is complying with a formal, higher-level requirement. Results show that a prominent focus on the social factors within an STS framework could help reduce unpredictability on the technical side and may improve communication within the system to help reduce adoption time, especially if and when accompanying a new, formal work process.