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Several industrial-scale HydroFloat separators have recently been installed at Mosaic?s South Fort Meade beneficiation plant for the purpose of improving phosphate recovery and throughput capacity. This technology was implemented after numerous laboratory, bench-scale and on-site, pilot-scale test campaigns. The results from this detailed test work provided sufficient justification for the complete retrofit of the existing coarse and ultra-coarse flotation cells. Data indicate that the metallurgical results obtained with the full-scale separators are consistent with that obtained during both the bench- and pilot-scale evaluations. The benefits, theory of operation and commissioning of the equipment are also discussed.

Jan 1, 2007

By R. John Caulfield

The primary water supply system for the City of San Francisco and adjacent peninsula areas consists of aging and deteriorated pipelines crossing under the San Francisco Bay (the Bay). This system is highly vulnerable to seismic damage from the nearby San Andreas and Hayward fault zones. The Bay Tunnel Project will replace the existing system with a 8-km-long (5-mi-long) tunnel underneath the Bay. The tunnel will be constructed using earth pressure balance methods and will have a two-pass lining system of precast concrete bolted, gasketed segments for initial support, and a welded steel pipe final lining. The project challenges include tunneling through both soft ground and rock conditions without any intermediate shaft access over the entire alignment. Seismic performance criteria include maintaining service flows after a large earthquake.

By Greg Sheppard, Eduardo Nebot

Australian researchers have developed new technologies aimed at improving safety and productivity at openpit mines. A data acquisition and feedback system for electric rope shovels has been shown to substantially reduce cycle times and decrease excessive machine duty caused by stalls. This data acquisition system was developed by the Cooperative Research Center for Mining Technology and Equipment (CMTE). It has been tested on a P&H 4100A shovel at Coal & Allied’s Hunter Valley operations and a P&H 4100XPB at BHP Billiton Mitsubishi Alliance’s Goonyella Riverside Mine in Central Queensland. In addition, CMTE member P&H Mine Pro Services has used the technology to acquire field data from a P&H 4100XPBrope shovel at RAG’s Belle Ayr Mine in Wyoming’s Powder River Basin.

Jan 1, 2002

By K. V. Raj

In the mining industry, computational fluid dynamics (CFD) modeling is used extensively to simulate air flow in underground mines. CFD modeling of pollutant transport in open-pit mines is relatively new. Modeling the actual pit geometry of an open-pit mine and the open domain is complex. The complexity is primarily due to the faceted geometry of an open-pit mine with its numerous associated sharp features. Important issues that are not considered carefully at the geometry level are generally propagated to the subsequent processes. Several challenges and pitfalls are encountered in modeling pollutant transport in open-pit mines. These challenges and pitfalls are related to the geometry, meshing, boundary conditions, and turbulence modeling parameterization. An appropriate mesh selection is critical. A detail discussion of the meshing of the domain of an open-pit mine is presented in this paper. The selection of an appropriate turbulence model, such as kappa-epsilon (?-e), large eddy simulation (LES), Reynolds stress model (RSM), etc., to obtain the best possible solution is equally significant. This paper discusses the various challenges in modeling the pollutant transport process in an open pit and some of the approaches adopted to address these challenges.

Feb 27, 2013

By A. Moergeli

The Swiss are currently building the world’s longest tunnel, the 35-mile long Gotthard Base Tunnel. At Sedrun, for the first time in tunneling, four Roadway Support Machines will drive through most difficult ground, supporting variable diameters of up to 13 m. The machines are prepared for their first deployment. At Amsteg, two Hard Rock TBMs have successfully crossed a known fault zone by applying full circle steel arches and shotcrete immediately behind the cutter head. Comparisons between Drill& Blast and Hard Rock TBM are shown.

Jan 1, 2005

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 Fred Breu, Ronald E. Heuer

INTRODUCTION The Point Lepreau nuclear generating station was constructed in the late 1970's and early 1980's by the New Brunswick Electric Power Commission. Point Lepreau is a small peninsula on the north shore of the Bay of Fundy, about 55 km west of St. John, New Brunswick. Cooling water for the plant was to be obtained from and discharged into the Bay of Fundy by the system of shafts and tunnels illustrated in Fig. 1. The design engineer for the cooling water system was Albery, Pullerits, Dickson and Associates, Ltd., Toronto. Ferrera-Resco Ltd, Windsor, Ontario, was contractor for construction of the cooling water shaft and tunnel system, which was done between 1976 and 1979. The senior author was project manager for Ferrera-Resco, the junior author served as consultant to Ferrera-Resco on evaluation of certain geotechnical questions which arose during construction. SITE CONDITIONS Geology Except for limited overburden soils at the onshore shaft sites, the tunnels and shafts were constructed entirely in Triassic conglomerate, sandstone, and siltstone, with some shale interbeds. The bedding strike averaged about N6°E, The dip was to the west at about 30° along the Discharge Tunnel and 40° along the Intake Tunnel. Rock along the Intake Tunnel was mostly sandstone and siltstone and more thinly bedded, with RQ D generally in the range of 50 to 60%. Rock along the Discharge Tunnel tended to be coarser sandstone and conglomerate and more thickly bedded, with higher RQ D averaging about 80%. In addition to bedding joints, two other joint systems were identified

Jan 1, 1985

By Susan P. Taite, Alain R. Charest, Peter D. Lewis

The El Sauzal deposit is a classic, high sulfidation, epithermal gold system located in the southwestern Chihuahua state of Mexico (Fig. 1). A Francisco Gold geologist discovered the prospect in1995. El Sauzal was encountered as a result of an extensive grassroots exploration program in the rugged, dissected volcanic terrains of the Sierra Madre Occidental, around the historical Batopilas silver camp. At El Sauzal, high grade gold is hosted within a series of more permeable, low-dipping, lithic and fine-grained dacitic rocks of early Tertiaryage. The mineralization appears tobe structurally and lithologically controlled. The alteration characteristics are typical of a high sulfidation system, including kaolinite, illite, alunite, dickite and pyrophyllite.

Jan 1, 2005

By Dave Ragland

The SDSU tunnel and underground station are the first of these type facilities to be constructed by the Metropolitan Transit Development Board. Because there is no previous experience, and because tunneling activities are associated with some risk, he MTDB has undertaken a very proactive and wide reaching program to identify and control risks during construction. Finally, because the tunneling activity and underground station is on the San Diego State University, MTDB is working closely with their staff to identify construction impacts and mitigation’s, and thus ensure a quality project for both agencies.

Jan 1, 2001

By Steve Kral

Invensys is a London-based supplier of automation and control systems to a variety of manufacturing and processing industries. Through its global subsidiaries, Invensys provides customized, advanced process control systems and networks for automating industrial plants, including mineral processing plants. The company employs more than 80,000 people worldwide in its four divisions. They include Automation, Control, Powerware and Software Systems. These four divisions work together to design the complete package for their customer’s automation and process-control needs.

Jan 1, 2002

By Stuart F. McTavish

Mechanically suitable grinding mills became available to the mining industry in 1908. Since then, mill operators have been searching for the best material and design with which to line the mills. These liner systems had to fulfill several criteria. Most important, they had to last long enough in an operating mill to protect its structure from the abrasive wear of the ore and the grinding media. In addition, they had to be capable of efficiently transferring the energy from the mill to the mill charge in order to facilitate the grinding process. And these liners had to be easy to install and remove. The first liners used were generally made of cast white iron, Hadfield manganese, unalloyed high-carbon steel and composites of steel and concrete or cemented in flint blocks or natural stone. In the early 1920s, pieces of solid rubber truck tires were used as emergency repairs for broken cast metal liners. Thus was rubber first introduced as a mill liner material. The first patent for rubber mill liners was awarded in 1921 to James Denny and Rolla Watson, both of the Coniagas Mine in Cobalt, Ontario, and to Dale Barnum of the Comstock Lode in Virginia City, NV. This original design was covered under US Patent No. 1470597. It had a fabric backed rubber that was bonded to the shell of the mill.

Jan 1, 1990

By James J. Brady, Joginder S. Bhore, Robert B. Gordon, Jimmy W. Honeycutt

The authors of this paper have a combined construction experience of 70 years. They have served as engineers and managers on projects throughout the United States and Canada. Approximately 50 shafts have been sunk under their direct and daily participation. Several shafts have been selected from each of their experiences and have been briefly summarized here. SHALLOW SHAFT SINKING Sinking shallow shafts in highly urbanized areas adds an additional set of problems to those encountered in normal sinking operations. During the time between July, 1975 and early 1981, a series of shafts were sunk for The Washington Metropolitan Transit Authority. All of these were located along the "A" line, starting soon after the route departed from its path along Connecticut Avenue, proceeding to Wisconsin Avenue and then along Wisconsin Avenue to the city line at Western Avenue. (See WMATA System Map, Figure 1) The first three shafts were subcontracted from Morrison-Knudsen & Associates, Contract A9a, in July, 1975. They were: Albemarle Street - 27'6" diameter, 78'O" deep Brandywine Street - 30'6" diameter, 88.6' deep Ellicott Street - 33'0" diameter, 110'0" deep

Jan 1, 1985

Caterpillar’s 797 327-t (360-st) mining truck is currently being tested at the company’s proving facilities. Mine evaluations began in the second quarter. The unit will be commerically available in North America in 2000 and worldwide in 2001. The new model is the largest of Caterpillar’s off high-way truck line. In addition, the company has replaced its 966F series II and 970 F wheel loaders with the966G and 972G models. 797 mining haul truck Caterpillar developed the 797 mining haul truck in response to mining companies seeking to reduce cost per ton in large-scale operations. The 797 is sized to work with loading shovels used in large mining operations. And Caterpillar will match the body design to the material being hauled, to optimize pay-loads.

Jan 1, 1999

By Christopher J. Bise

INTRODUCTION Before a mine is planned in detail, a preliminary analysis is often conducted. This preplanning permits the mining engineer to make a rapid assessment as to whether or not a particular mining property warrants further consideration. In fact, a properly conducted preplanning phase can come within 10% to 20% of the actual results, thereby saving the mining engineer valuable time before committing himself to a fine-tuned analysis. The questions to be answered by mine preplanning are (1) What will be the operating conditions for the mine? and (2) How long will it take to complete the project? To answer these questions, calculations dealing with reserve estimation, production planning, man- power planning, and project scheduling are conducted. The following sections discuss these various phases of mine preplanning in greater detail. RESERVE ESTIMATION The estimation of the various characteristics of a reserve, such as quantity, grade, and thickness, is an ongoing process throughout the life of a mining venture. However, the reserve-estimation phase of mine planning is more closely associated with the preplanning phase. There are many different techniques employed in reserve estimation of solid mineral deposits; variations among them are introduced because of such considerations as ease of application or level of accuracy. In any event, each technique is developed in the following manner: (1) the mineral body is represented pictorially and then subdivided into blocks related to one or more samples of exploration data, (2) the area and volume of each block is determined, (3) the volumes are converted to representative tonnages (or, for example, grades), and (4) the results are tabulated. To illustrate this procedure, the polygonal (area-of- influence) technique will be presented due to its ease of application, flexibility in dealing with different deposits, and general acceptance. The polygonal method assumes that all characteristics of a mineral body extend halfway between a point of observation and any other point of observation. The explored portion of the mineral body is represented by polygonal prisms whose depths relate to the characteristic in question (grade, thickness, etc.) and whose plane bases relate to the area of influence of each point of observation (drill hole, etc.) as shown in Fig. 1. The polygons must be constructed in a definite order, usually clockwise and from the periphery to the center of the deposit. Table 1 can then be used to calculate the characteristics in question. Since, by definition, the polygonal method assumes that the characteristics of a mineral body extend half- way between points of observation, it becomes readily apparent that the evaluation of a vertical-drill hole exploration program requires that the sides of the polygons be formed by the intersection of perpendicular bisectors (Fig. 2). Figs. 3 and 4 show correct and incorrect construction of the polygons. The criterion for correct construction of the polygons is that all points within a particular polygon must be closer to its rallying point than those located in any other polygon. This is clearly not the case for certain points that are located in the polygon containing rallying point B in Fig. 4. Although this method can be used where the drill holes are irregularly spaced, calculations become less tedious when a square net (Fig. 5) or a chessboard (Fig. 6) grid is adopted. The numbers shown in Figs. 5 and 6 represent the relative weight for each of the shaded areas. In general, the greater the number of polygons, the more continuous the mineral body, and the more regular the grid, then the more accurate the computations will be. PRODUCTION PLANNING Before an acceptable evaluation of the production potential of a mine can be determined, a thorough exploration program should be conducted. It seems obvious that the nature and properties of the deposit and adjacent strata, the presence of impurities, and other mining conditions should be adequately determined prior to production planning and equipment selection. The lack of sufficiently detailed knowledge of the many mining parameters has led to the failure of numerous operations. For example, targeted production tonnages and equipment sizes for a coal mine are intimately related to the seam thickness. Needless to say the quality of information that is gathered from an exploration program can have a tremendous impact on the production plan. Production plans are developed initially by determining reasonable shift tonnages per operating section. Most of the time these values are developed from his-

Jan 1, 1986

By Shemek Oginski

The 5 km (16,194 lf) of 6.1m (20 ft) diameter TBM driven tunnel built by the J.F.Shea Co. will serve as sewage overflow storage. The TBM tunnel and four connecting tunnels excavated by drill and blast methods in hard granite will remain unlined. Based on the Geotechnical Baseline Report (GBR), the Contract documents provided a design with no required pattern of rock bolts, no probing, no pre-excavation or consolidation grouting, and lastly, no final lining of the tunnels was deemed necessary. This paper will provide a general overview of these topics with the emphasis on the actual ground conditions encountered versus the projected conditions provided in the GBR and how the GBR reflected the design of the project. Proposed modifications to the temporary and permanent ground support will be presented and the necessity of probing and pre-excavation grouting will be evaluated.

Jan 1, 2005

By Graham Davey

High-speed stirred milling is a relatively new method of grinding in the metalliferous process industries. However, it has been widely used in the industrial mineral field for more than 30 years. Many existing metallurgical operations are looking to maximize economic return from existing deposits this requires new thinking and technologies. The operating experience of two copper operations is discussed here to show the effect of the introduction of the Metso Stirred Media Detritor (SMD), a new type of high speed stirred mill. Both operations have derived significant metallurgical benefits from this new technology. The benefits and process difficulties are explained. The initial drive in high speed stirred milling technology was toward ultra fine grinding where the mill product has an 80 percent passing size of 15 µm (937mesh) or less. More recently, a number of installations have occurred in a more conventional regrind setting. Few conventional copper concentrators require such fine grinding to attain satisfactory copper grades and recoveries. So other advantages must be considered here rather than just the ability to grind fine with good power efficiency.

Jan 1, 2004

The Anshan Iron and Steel Co. (AISC) broke its steelmaking design capacity in 1978, bringing its total production of steel products to 6.86 Mt. Located south of the industrial city of Shenyang, Liaoning Province, in northeastern China, it is by far China’s most important iron and steel complex, ranking twentieth among world centers. The complex represents a unique blend of old ecluipment and new ideas for increased production and improved products. Under a state plan, the Chinese hope to raise capacity to almost 15 Mt/a in the future. Originally started by the Japanese in the early 1920s, Anshan has had a rather turbulent 60-year history. It was disassembled by the Soviets after World War II, only to be reassembled by them in the 1950s. Production was also suppressed during the Cultural Revolution. Since the present-day organization, AISC, emerged, the center has experienced progressively improving conditions as well as increased production. Today, the center includes 10 blast furnaces, 24 open hearths, and two basic oxygen units, designed for 7 Mt/a ironmaking and 6.5 Mt/a steelmaking. In addition, it has six batteries of cokemaking facilities with combined 4.4-Mt/a capacity. Solid Iron Resources Anshan’s iron resources consist of a proven reserve base of over 7 Gt of 30~0 Fe, according to Kao Yang, president of the Anshan Iron Mining Co., a subsidiary of AI SC, Most of that, he continued, is amenable to surface mining. Five major mines located to the north and northeast of the city of Anshan are the principal iron ore producers. These mines trend in a somewhat circular manner and combined, represent an estimated 28.6 Ylt/a of ore capacity. In addition, some 2.2 Gt of magnesite, a necessary ingredient in steelmaking, are also part of the reserve base, according to Kao. Annual production is around .2 Mt/a of 47% magnesite, well over the steelmaking center’s annual requirements, Excess production is shipped to other steel-making centers. The largest of Anshau’s open-pit mines is the Chitashan operation with a design capacity of 8 Mt/a. Ore reserves here are well over a billion tons of 30% Fe. Earlier plans to expand production at this mine to 15 Mt/a, with the help of US Steel, have been temporarily shelved. The other mines in the district and their rated design capacity are: Kungchangling, 7 Mt/a; Donganshan, 6.4 Mt/a; Dakushan, 4.2 Mt/ti; and Yenchienshan, 3.0 Mt/a. The Kungchangling mine is the richest in terms of ore grade at 6076 Fe. Reserves are somewhat smaller at 100 Mt. The unit also operates a small shrinkage stoping operation. Ore grade at the other mines is usually 30-327. Fe. Llost mines operated at reduced capacity during 1979 owing to a natural gas shortage at the mills. The general

Jan 3, 1980

By Lane White

In mid-April 1992, MINING ENGINEERING mailed a survey questionnaire relating to mining shovels and hydraulic excavators to 125 SME members working at surface mines or at the headquarters of companies that operate surface mines. The mailing was directed to individuals whose titles indicate that they have management or mine planning responsibilities for surface mining operations. A total of 56 usable surveys returned by June 17 are the basis of this report. Precious metals mines Eighteen precious metals mines or mining companies returned completed surveys in time to be included in this report. Of these, 14 use hydraulic shovels only for both ore and waste, I uses both hydraulic and rope shovels, and 2 use Caterpillar 988 front-end loaders for both ore and waste. (Of the latter 2, neither expects to be in the market for a shovel in the next three years. I of these 2 placed Harnischfeger P&H number one and O&K number two in response to the question, "Based on your current knowledge of their machines, which manufacturer would you likely chose to supply new shovels or excavators to a mine or mines operating under your responsibility, if you were in the market?") Another uses front-end loaders, make not designated. The latter does not expect to be in the market for mining shovels or excavators within the next three years. Of the final total of 14 precious metals mines using only hydraulic excavators to load ore and waste, 8 use Hitachi excavators only, 1 uses Demag excavators only, 1 uses Liebherr excavators only, 1 uses O&K excavators only, 1 uses Harnischfeger P&H and O&K excavators, 1 uses Harnischfeger P&H and Hitachi excavators, and 1 uses Hitachi and Demag excavators. Of the 14 precious metals mines using only hydraulic excavators, 7 use excavators in the 7.6 to 11.5 m; (10 to 15 cu yd) size range. Of these 7, 5 use only excavators in this size range, and they are used to load both ore and waste. 1 of the 7 also uses 11.5 to 17 m' (15 to 22 cu yd) excavators, and I also uses a 17 to 23 m3 (22 to 30 cu yd) excavator. Of the 7 remaining of these 14 precious metals mines that use only hydraulic excavators, 3 use 11.5 to 17 m' (15 to 22 cu yd), 2 use 17 to 23 m3 (22 to 30 cu yd), and 2 use less than 7.6 m' (10 cu yd) units.

Jan 1, 1992

By F. F. Peng

The raw-coal feeding system and the upward medium current flow in a dense-medium vessel (DMV) are, in addition to the residence time of particles in the separator, important factors for efficient coarse particle separation. The feed material from a raw coal screen and/or pre-wet screen merge with the major volume of circulating medium as push medium, guided by an adjustable submergence baffle plate deep fed into the separator for effective separation. The remaining volume of the circulating medium enters from the purge and drain hoppers at the bottom of the DMV. This generates a gentle upward medium current flow in the separator, which prevents dense medium stratification/settling and merges as part of the push medium. A two-dimensional, two-phase model developed using computational fluid dynamics (CFD) is used to describe the flow pattern and evaluate the function of the dip plate for understanding the mechanisms of particle separation in the separator. The particle movement in the DMV is also tracked to investigate the major operating parameters affecting the separation performance of the DMV. The simulation results of the DMV separation performance are validated by in-plant test data.

Jan 1, 2007

By W. M. Shaver, W. R. Dengler, F. A. Edwards

INTRODUCTION The Macassa Division of Lac Minerals Ltd. is a high grade gold mine that has been operating in Kirkland Lake, Ontario for the past 51 years. It produces approximately 120,000 tonnes of ore per year, averaging approximately 18.7 grams per tonne (0.45 ounzes per ton) of gold. Over the years, the ore body has been developed to a point where mining takes place below the 1,220 m (4,000 feet) elevation and 1,830 m (6,000 feet) west of the original shaft. The mine is currently serviced by two surface and two winze shafts. (Figure 1). The ore body extends below the 1,930 m (6,400 feet) Level which is the bottom of the existing mining operation. An ambitious underground exploration program has substantially increased these reserves. Concurrent with the discovery of greater reserves, has been rapidly escalating mining costs, particularly labour which constituted 66% of the total cost in 1981. These costs continued to escalate as the major proportion of mining was carried out to the west, far away from the existing hoisting systems. This required three lift hoisting for men, materials and ore. I n addition to the increased travel time and ore handling expense, increased humidity and temperature and ventilation and compressed air losses have added to the inefficiency of the operations. As a result, studies were initiated in 1980 to assess the future of the Macassa operation.

Jan 1, 1985