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By Edward H. Jr. Boyle, Paul R. Thomas

Introduction It is estimated that nearly 40% of all the gold ever mined in free world countries has been produced by South African operations. There is concern that this immense productive capacity will soon decline. Such a decline could reduce world gold supply and lessen the ability of market economy countries (MEC) to exert the major influence upon the world gold market. This paper addresses three general issues concerning South African gold production: • How much gold remains to be recovered from the demonstrated resources of the 44 evaluated South African mines; • How long can production at current levels continue; and • What will be its cost. Table 1 provides production data on the world's 10 largest producers for the years 1971, 1981, and 1983. As shown, South African gold production declined significantly from 1971 through 1981. As of 1981, annual South African gold production had dropped by more than 311 t (10 million oz) in 10 years. Despite this, its mines still produced 656 t (21 million oz) that year, about half the world total. From 1981 through 1983, this trend was reversed. Annual South African gold production increased by more than 21.8 t (700,000 oz). The trend reversal was also evident in the US, Canada, and Australia. This illustrates the general, inverse relationship between gold price and gold production. In South Africa especially, as gold prices increased substantially during the 1970s, the average grade of ore mined (pay limit) was lowered as new, lower grade areas and materials were exploited. Gold production declined in volume. But gold revenues increased, and the lives of the operations were extended. The 1981-83 period was one of declining (US dollar-based, average annual) gold prices that resulted in increasing South African production as average ore grades were raised. South Africa currently accounts for 50% of world production (Fig. 1). Figure 2 illustrates South Africa's contribution to total MEC production in 1971 and 1983. Although South Africa's relative share of production has declined, it still represents the single most important source of new gold supply. In 1983, it supplied more than 65% of total MEC production. South Africa currently produces more than twice as much gold as the Soviet Union (ranked second in world production), and 11 times more gold than the US (ranked fourth in world production). Barring major discoveries, South African gold production is expected to peak in 1987 and begin to decline again throughout the 1990s. The rate of decline is ex-

Jan 11, 1984

By S. Suwansawat, D. J. Maconochie, C. C. Chang

This paper describes the overall delivery of the tunneling for the Mass Rapid Transit Authority of Thailand’s Chaloem Ratchamongkhon Line in Bangkok and the constraints provided by the alignment. Eight earth pressure balance tunnel boring machines were employed under two major civil works contracts to drive approximately33 kilometers of tunnel in soft saturated ground beneath the crowded streets of Bangkok. Responsibility within the contract for building damage provided an inherent control for ground movement arising form tunneling when the right of way was narrower than the influence zone. These limits affect the earth pressure balance requirements and permissible ground loss. The methods adopted to limit ground movements and deal with the various obstacles to tunneling influenced the design and operation of the machines. The challenges provided by the need to tunnel through numerous lines of piled foundations of canal bridges and overpasses crossing the alignment are described.

Jan 1, 2001

By M. I. F. S. Cruz, R. Pedersen, F. J. A. S. Barriga, A. Dias, A. F. A. Marques

"Underwater hydrothermal vents are known since the 1970s and their importance for the global economy is growing as new discoveries and new assessments are made each year (Cherkashov et al., 2010; Corliss et al., 1979). The similarities of seafloor massive sulfides, representing the younger versions of the well exploited on land volcanogenic massive sulfides, bring an increased awareness to the potential of the sea (Ajan G. Galley, 2007; Hannington et al., 2011; Herzig and Hannington, 1995). The Arctic Ocean presents itself as an opportunity to study new interest areas and numerous hydrothermal systems (active and inactive) were discovered along the Arctic Mid Ocean Ridge (AMOR) (Pedersen et al., 2010b). The Mohns ridge is an ultraslow spreading ridge of the AMOR (Vogt, 1986) where two hydrothermal vent sites were recently discovered, the Jan Mayen and the Loki’s Castle (Pedersen et al., 2010a; Pedersen et al., 2009; Pedersen, 2005). Here we compare these two Arctic hydrothermal systems, which represent two well-differentiated end-members of hydrothermal fields in the region."

Sep 1, 2014

By Steve Kral

The coal mining industry in the western United States is seeing the same boom as the rest of the country and the world. Most coal mines in the West are operating flat out as the nation’s appetite for energy continues to grow. And many of the coal mines have either increased their production capacities or are in the process of doing so. However, transportation issues along with environmental restrictions are keeping many mines from expanding even further. Some coal companies held off on further expansion plans until Congress and President Bush could agree on a national energy policy, one that recognizes coal as the nation’s leading source of electricity. In August, Congress passed and the president signed into law such a measure (see Washington Survey, page 7). The legislation includes research funding for clean coal technologies. So western and eastern coal could become even more important in the national energy picture. This is particularly true as supplies of natural gas diminish and the price of oil continues to increase.

Jan 1, 2005

By Klaus Rieker

North of Antwerp central train station, two single-track tunnels for the high-speed train line between Brussels and Amsterdam were constructed. At the same time, the central train station was modified to a through station. Both 1.23 km tunnels are situated in the Antwerp sands and were constructed using a slurry shield machine. Due to the inner city location, the tunnels run over their entire length underneath structures, in some cases with only minimal clearance. The paper deals with these challenging situations. In addition, the tunnel boring machine, the tunnel lining and measures to limit settlements will be introduced.

Jan 1, 2007

By Gregory Yates

INTRODUCTION Project Description The Silver Line is a Bus Rapid Transit (BRT) Line and is Boston?s newest transit service. Silver Line Phase I extends along Washington Street entirely on the surface in priority bus lanes from Dudley Station in Roxbury through the South End and Chinatown neighborhoods to downtown Boston. The Phase I opened in July 2002. Silver Line Phase II consists of an underground transit tunnel from South Station to the South Boston Waterfront with underground stations at Courthouse and World Trade Center to Silver Line Way east of D Street. Phase II continues through the Ted Williams Tunnel to all the terminals at Logan Airport, and on the surface to the Boston Marine Industrial Park and City Point. Phase II opened in December 2004. Silver Line Phase III is a one mile tunnel connection to the existing Phase II tunnel in the vicinity of South Station and will eventually portal on Tremont Street just north of Marginal Road. After leaving the portal, the buses will use dedicated bus only lanes on the surface roadway network to connect to the Phase I service. Figure 1 shows the alignment of the Silver Line upon completion of the Phase III project.

Using a series-model of an automotive short range radar sensor (SRR) and a recently completed experimental radar system, field tests have been performed in a surface mine. It was examined, to what extent low-cost electronically scanning radar sensors can provide useful data for assistance systems on large scale mining machines. Simple sensors are useful for anti-collision safety zones or hopper car automation. The more complex and sophisticated experimental radar system using digital beam-forming can clearly detect and map the contours of trenches and slopes. The overall promising results refer to many more potential applications for electronically scanning radar in surface and underground mining as a reliable alternative to mechanical laser scanners.

Jan 1, 2007

By Z. T. Bieniawski

Geomechanics signifies the science and engineering of soil and rock materials and of rock masses. It is a field of professional practice and research that draws heavily on the elements of soil and rock mechanics. Geomechanics contributes to a number of disciplines: mining engineering, civil engineering, geological engineering, petroleum and natural gas engineering, and engineering geology (including the elements of geohydrology and geophysics). These disciplines are involved in the design and construction of such projects as mines, tunnels, foundations for structures, excavated rock slopes, dams, shafts, boreholes, oil reservoir wells, underground storage facilities for oil and gas, and hazardous waste repositories. Geomechanics allows us to improve both our environment and our quality of life. In the context of this Handbook, the scope of geomechanics is discussed mainly from the point of view of applications to mining engineering. However, the coverage of the subject mate¬rial is so comprehensive that it is relevant to other disciplines as well. Section 10 covers the field of geomechanics in a structured fashion, beginning with the fundamental principles and leading into practical applications in mining engineering. Throughout the treatment of the subject, knowledge of geologic conditions is assumed since this is discussed in other sections of the Handbook. An important feature of this section is a series of practical examples illustrating the various aspects of geomechanics. Since geomechanics is concerned with both soil and rock mechanics, Chapter 10.1 introduces the fundamentals of soil

Jan 1, 2008

By David Jurich, Joseph N. McDivitt

INTRODUCTION South Coast Water District (SCWD) operates the Beach Interceptor Sewer Tunnel(BIST) in South Laguna, Orange County, California between Monarch Beach and Aliso Beach (Figure 1). The 10,200-foot long BIST houses a 24-inch gravity Techite sewer pipeline critical to the SCWD Sanitary Sewer Collection System. The original tunnel and sewer pipeline were constructed in 1954 and the sewer line was replaced in 1974.Periodic inspections by sewer pipeline maintenance crews documented deterioration of specific intervals of the tunnel. Rotting timber supports and rock falls in the tunnel as a result of the deterioration were endangering the sewer pipeline and a 731-foot section of tunnel located at Thousand Steps Beach was determined to be in immediate need of repairs. SCWD and consultants Hatch Mott MacDonald (HMM) and Tetra Tec prepared a Work Plan for emergency tunnel stabilization and pipe protection measures that was implemented in January 2007. Normal access to the beach and the section of tunnel requiring repairs was limited to public stairs referred to as Thousand Steps and, therefore, all materials and equipment needed for the work were transported to the beach by ocean-going landing craft. Additionally, the emergency repairs had to be completed without taking the pipeline out of service. Numerous environmental, logistical and operational requirements had to be overcome to complete the challenging emergency repairs. GEOLOGICAL SETTING The Laguna Beach area is located in the Peninsular Ranges of Southern California. The project area is located on the southwest flank of Niguel Hill along marine wave-cut cliffs and slopes. The tunnel was excavated in the San Onofre Formation, a marine deposit, characterized by abrupt lateral and vertical changes in lithologies that vary from boulder to cobble and gravel size breccias to medium coarse sandstones with gravel, sandy claystone and siltstone. The interval of the tunnel that required repairs is located within the San Onofre breccia, a moderately-to-well cemented, poorly bedded to massive unit with angular to subangular boulder and cobble sized clasts of schist. The sandy silt matrix of the breccia is composed of quartz, feldspar and schist grains (Figure 2). GENERAL TUNNEL DESCRIPTION The approximately 6-feet high by 6-feet wide 10,200-foot-long BIST was hand mined in 1954 at the base of the coastal cliffs. Primary access is through twenty-one access adits from public and private beaches. The tunnel is located in an easement that extends beneath private property with residential structures situated 50 to 80 feet above and horizontally in close proximity to the tunnel alignment. Most of the tunnel is horse-shoe shaped and unsupported, but approximately 3,000 feet is supported by timber

Jan 1, 2007

By M. Wickham

Design of an open pit backfill requires an understanding of highly varied processes including slope stability, hydrogeology, pit lake chemistry, climate, runoff, and mine waste behavior. Dynamic systems modeling (DSM) provides flexibility to the designers of open pit backfill, allowing them to directly integrate many different physical processes and varying levels of complexity. DSM also provides for the efficient application of uncertainty analysis to define a range of possible results, the sensitivity of the results to uncertainties in model inputs, and the value of additional data. This paper presents the results of an analysis using DSM to evaluate a pit backfill design at an Arizona mine. The objective of the partial backfill was to stabilize an active slope that threatened facilities adjacent to the pit. DSM was used, in part, to develop a pit lake water balance model for evaluating the influence of the backfill on the ability of the pit to maintain passive hydraulic containment of groundwater and surface water inflows and for evaluating costs for various backfill scenarios.

Jan 1, 2001

By S. A. G. Poppen, M. B. Mirza, A. I. Cooley

The U.S. Department of Energy (DOE) is responsible for siting and constructing a licensed geologic repository for commercially generated high-level nuclear waste. Within DOE, the Office of Civilian Radioactive Waste Management (OCRWM) Program has this responsibility. To accomplish this mission, the OCRWM Program is engaged in a multidisciplined effort to identify, qualify, and develop repository sites. The current strategy of the OCRWM Program is to identify candidate repository sites in basalt, tuff, and salt and to develop exploratory shafts at those sites. Within OCRWM, the Salt Repository Project Office (SRPO) identified the salt site for the development of exploratory shafts. The proposed Exploratory Shaft Facility (ESF) in salt will have several primary purposes. The shafts will provide access to the reference repository horizon to permit in situ testing of the salt horizons in order to satisfy the following data acquisition needs: • Verification of the salt repository design parameters and validation of performance assessment models • Demonstration of the constructibility • Capability to adequately seal penetrations into the salt An exploratory shaft is required by 10 CFR Part 60 for the conduct of in situ testing at depth prior to submittal of a license application for construction authorization of a repository. Therefore, construction of an ESF will also facilitate the licensing process.

Jan 1, 1987

By H. Lyn Bourne

This is the fifth annual tabulation of mineral royalty information. This tabulation, like the previous editions, includes all of the earlier data. There are also 60 new entries. In addition to royalty information, some entries show the cost of purchased reserves. Two articles relative to the evaluation of minerals reserves appeared in December, 1986. R.H. Paschall (In the Aggregate, ME, p 1139) wrote a good article, although it lacked specific royalty data. However, this author takes exception to two ideas in Paschall's column. Paschall contends that the royalty rate does not affect the mineral appraisal. This present author could not disagree more. Paschall also claims the location of an industrial mineral deposit is the only serious or practical caveat in comparing royalties. Comments received here from readers helped make the list of caveats that are cited each year. The readers will decide which factors influence the mineral value for their commodities of interest. Paschall's point about the relationship of the parties who are negotiating a royalty agreement is important and very well taken. The other article, written by William Vernon (Pit and Quarry, December 1986), gives a step-by-step process on how to conduct a mineral appraisal. The article cites three reasons for an appraisal: transfer rights; collateral for a loan; and taxation. A fourth reason is to establish adequate compensation for reserves lost through condemnation. This author has appeared in several court cases where compensation for loss of mineral reserves through condemnation required a mineral appraisal. Royalty rate becomes an important factor in the appraisal process, although the Pit and Quarry article refers to that part of the valuation equation as "profitability." Both articles were well written and are recommended reading for those interested in mineral valuations. The same caveats that have appeared in previous columns relative to factors that influence the value of reserves are restated. The data in the table serve as a general reference and are not intended to present an absolute scale of reserves costs. Several factors influence the value of any mineral commodity. The factors include: • location/transportation - especially significant for most industrial minerals; • market conditions both for the commodity and the company acquiring the right to mine; • quality or grade of the deposit as it reflects the amount of processing/beneficiation necessary to produce the finished product; and • legislative restrictions and conditions for mining a given material at a given site. These and other factors will significantly influence the cost of reserves. The table shows the range of royalties and the variations in the basis of computing the fees. In a few instances, it gives the cost of acquired reserves based on purchase price and quantitative estimates of the material in place. The table lists the commodity in column 1, and the subsequent columns give: • the location by state, US geographic area, or Canadian province ; • the cost - R for royalty and P for purchased cost; • the year in which the lease or purchase agreement occurred; and • comments or footnotes for more information. The cost column requires more explanation. The units may refer to cubic yards (/cu yd), cubic feet (/cu ft), short tons (/T), or acres (/A). 1 cu yd = 0.76 M2 1cuft = 0.28m3 1 st = 0.9072 t 1 acre - 0.4047 ha or m2

Jan 7, 1987

By Tim O’Neil

“America’s mining industry brings good jobs to communities across America and provides the energy, minerals and equipment that are vital to our economic security and our way of life.” That was the surprise videotaped greeting from President George Bush at the official opening ceremony of MINExpo 2004in the Las Vegas, NV Convention Center. Jack Gerard reinforced the upbeat mood at MIN-Expo. He praised Nevada Gov. Kenny Guinn for his support of the mining industry, the state’s largest manufacturing sector. Gerard is the president and chief executive officer of the National Mining Association, the sponsor of MINExpo 2004.

Jan 1, 2004

By D. Loring, J. Almgren

Climax Molybdenum Company’s Henderson Mine is a large panel caving molybdenum mine located about 43 miles west of Denver, Colorado. Three Joy M120-72-880 fans are installed in parallel on the No. 1 exhaust shaft. Throughout the mine’s history, ventilation changes such as the completion of the No. 5 exhaust shaft have decreased the utilization of these fans. To optimize fan performance they have been run with the full complement of 16 blades, down to as few as four blades. Since the completion of ventilation upgrades associated with the Henderson 2000 project, one surface fan has been operated under normal conditions with 10 or 12 blades. With the completion of a new network model of the Henderson ventilation system, a tool was built to develop fan curves for possible future fan configurations and predict future fan performance. This paper describes the tool and its use at Henderson.

Jan 1, 2007

By M. Martins

This work presents and discusses the influence of the surface tension (gLV) of methanol/water mixtures on the flotation response of apatite versus gangue minerals conditioned with flotation reagents (75 g/t cornstarch and 100 g/t Berol 867) at pH 10.6. Berol 867 is a collector composed of sodium alkyl sarcosinate plus nonionic surfactant. The highest Schulz efficiency of separation (recovery of apatite minus recovery of gangue) was achieved at ?51.0 mN/m. The critical surface tension of wettability (gC) of apatite was found to occur at 34.7 mN/m when determined by means of gamma flotation experiments, and it was 33.9 mN/m when determined by Zisman?s approach.

Jan 1, 2009

By Robert S. Shank

Introduction The Pinto Valley open-pit copper mine is located in southern Arizona, 11 km (7 miles) west of Miami. Production at Pinto Valley began in 1974. About 350 Mt (386 million st) of ore and waste was removed by the end of June 1982. At that time, the mine was using more than 90 major equipment items with a total mobile fleet numbering 320. Some of the major equipment consisted of four Marion M4 rotary drills; six P&H 15, 11.5- and 19.1-m3 (15- and 25-cu yd) shovels; and 24,136- and 154-t (150¬and 170-st) Wabco haulage trucks. This equipment was used to move more than 139 kt/d (154,000 stpd) of ore and waste. The mill was processing more than 50 kt/d (55,000 stpd) of mine ore. Shutdown A two-week vacation shutdown began in July 1982. Maintenance jobs were scheduled, and most employees left for the vacation. During the vacation period, copper prices fell below $1.32/kg ($0.60 per lb). Inventories remained at alarmingly high levels. At this point the mine was losing more money operating than it would by being shut down. The vacation shutdown was first extended to five weeks. But, after further evaluation, the mine was shut down indefinitely. In Dec. 1982, Cities Services Co., owner of Miami Operations (which included the Pinto Valley mine and mill), was acquired by the Occidental Petroleum Corp. On March 1, 1983, Occidental sold the operations to Newmont Mining Corp., and Newmont created Pinto Valley Copper Corp., as a wholly owned subsidiary. Copper continued to be produced by the Pinto Valley solvent extraction-electrowinning (SX- EW) plant because of its low cost per pound of production. To ensure proper equipment care during the shutdown, maintenance management was given three goals; • maintain the SX-EW plant; • maintain the environmental and pollution control systems such as domestic water pumps and mine dewatering; and

Jan 4, 1985

By Hugh R. Rhys

The question of the desirability of recovering cullet from MSW in order to recycle it into the manufacturing of glass containers remains a controversial one. The main factors appear to be: 1. The position of the Glass Container Manufacturers Institute (GCMI), as the trade association for most container manufacturers, is that post-consumer cullet is a vital source of raw material. Present requirements are for: a) Flint cullet b) Non-flint cullet of known mix proportions c) Mixed unsorted cullet of known mix propertions c) Mixed or non-flint cullet of unknown mix proportions. A market balance for these products exists, and this might somewhat limit the outlets for (b), (c) and (d), or severely limit the outlet for (d) alone. 2. The color specifications are rather strict. With cullet admixtures of 20% of the melt or more, and the use of decolorisers in a flint furnace discouraged because their action is reducing in a process which requires an oxidising environment, color contamination in a flint furnace is serious.. For amber and green furnaces (reducing) it is less serious, but in order that the quantity of decolorisers may be controlled, the color balance (as a measure of the Fe and Cr content) of the admixtured cullet should be known. 3. Why not simply color analyze, either by a continuous on-stream or off-stream: photo-electronic analysis, or by systematic batch sampling (with some kind off electronic surveillance of the mainstream) and just send mixed, color measured cullet to only amber and green furnaces? The flint would-be simply included in the mix. This is probably technically feasible, but is subject to the market limitations noted in point1.

Jan 1, 1975

Mining steeply dipping coal seams is a difficult task in the mining industry. Prior to 1996, fully mechanized longwall mining methods along the seam strike direction were tried in China and other countries. Due to its larger coal reserve in steep seams, China made more but still limited progresses on mining in such seams than the other major coal-mining countries. In the last two decades, accelerated research efforts have been made to improve the mining technology in steeply dipping coal seams. Based on these works, a dynamic model of ?R-S-F? system under asymmetrical constrains in mining steep seam is established and the theory of strata control and hazard prevention begin to be formed. The key technologies for mining steep coal seams include: global and regional strata control methods in longwall face, methods for the longwall face machines to sustain static and dynamic loads, and flexible protection technology. These theory and technologies have been successfully applied to mining of steep coal seams of varying thickness and hardness, with hard and soft roof and floor, and with high potential of spontaneous combustion in China. In the recent years, the technology has been introduced to Russia, India, Uzbekistan and other countries where steep coal seams are mined.

Jan 1, 2012

By Carl Johnson, D. R. Todd

The Blue Ridge Low Level Outlet (LLO) was a design/build contract to provide a secondary means of discharging water from the Blue Ridge Reservoir. The project involved driving a 3.25 m (11 ft) modified horseshoe tunnel by 293.5 m (963 ft) long utilizing conventional drill and blast methodology. The intake shaft and structure were constructed inside of a sheet pile cofferdam surrounded by a maximum of 20.1 m (66 ft) of water. The shaft was excavated 4.87 m(16 ft) diameter to a depth of 12.8 m (42 ft) below the tremie slab elevation. Steel lining, including a transition from 3.66 m to 2.74 m (12 to 9 ft) diameter and a90 degree elbow were installed in the inlet shaft and then backfilled with concrete. This paper will describe the RFP phase, the design phase, challenges of the underground construction and contractual challenges.

Jan 1, 2005

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