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By Greg Wieland

Deep sewer tunnels are required to meet future growth demands of the City of Austin?s down-town redevelopment. The tunnel is 18,000 ft long and varies in finished diameter from 54 inches to 96 inches. The tunnel crosses under Austin?s Town Lake three times and there are four main work shaft sites. Geology, groundwater, foundations, downtown redevelopment, and an active, healthy community put significant constraints on the design. This paper discusses a major underground project for downtown Austin and discusses the risk considerations and the opportunities the design team took toward optimizing the project design for the construction phase.

Jan 1, 2008

By W. J. Atkinson

The first recorded discovery of diamonds in Australia was in 1851 in New South Wales. Subsequent prospecting has shown alluvial occurrences of diamond to be widespread through much of the Tasman fold belts of Eastern Australia. Production is estimated to be some 500,000 carats from several small alluvial fields. Despite extensive exploration, though, no primary rock source carrying significant diamond content has ever been confirmed in Eastern Australia. Conversely, diamond exploration of the older Western and Central Cratons of Australia during the past 30 years has discovered 12 fields containing 360 kimberlites, lamproites and lamprophyric volcanic pipes, dykes and other intrusives. Of those, 180 have been confirmed to be diamondiferous. Only one pipe, however, the 1200 Ma high-grade Argyle lamproite and associated nearby alluvials, has proved to be economically exploitable. Its current annual production is 40 million carats valued at about US$400 million. Production from the open pit will be sustainable until at least 2003.

Jan 1, 1995

By J. Kretschmann

Around the world, mining has been done for thousands of years for the benefit of humankind. The winning process in mining operations ends with the depletion of the deposit or its closure if the operation becomes economically unprofitable. After that, a period of post-mining follows which may last for a very long time and which is generally regarded as a period of hazards, risk and high cost. In the USA alone, approximately 500,000 abandoned mines do exist; worldwide, there are millions. In Germany, too, we have had to deal with abandoned mines for a considerable period of time now.

Jan 1, 2012

By D. Gu

Breakage of rock by machine is one of the major methods of excavation. With the development of modern engineering techniques, the advantages of using this method have become even greater. Improving efficiency and reducing the cost of rock breakage is the main goal of mechanizing the rock-breaking operation. For a given stratum, the efficiency of a machine excavation depends, to a large extent, on the design and method of application of the tools used. In a planetary cutter head, the subcutter heads move like planets around the main drive shaft. The general structure of the cutter head is shown in Fig. 1. As shown in this illustration, the main drive shaft (1-1) is connected to the tie bar (1) and, thereby, to a gear(5) that meshes with a fixed-gear ring(2). The subcutter head (4) is rigidly connected to the gear (5) by the subcutter-head axis (2-2). When the main drive shaft (1-1) rotates, the subcutter head (4) rotates around the axis (2-2), under the action of the tie bar and with the help of sleeve pipe (3).At the same time, axis (2-2) also rotates around the main shaft (1-1). As shown in Fig 1, is the angle between the main shaft and the subcutter-head axis.

Jan 1, 1995

By S. Dixon

The Peñasquito deposit in Mexico is one of the largest grassroots precious metal discoveries to be developed in recent years Minera Peñasquito, S.A. de C.V., a wholly owned subsidiary of Goldcorp Inc. has developed the Peñasquito property to produce an average annual production of 120 kilo tonnes of lead containing 0.5 million oz gold and 30 million oz silver and 250 kilo tonnes of zinc containing 20 thousand oz gold and 1.5 million oz silver.. The Peñasquito property covers a 39,000 hectare area in the western half of the Concepción del Oro district in the northeast corner of Zacatecas State, Mexico, approximately 24°45'N latitude/101°30'W longitude. The sulfide reserves are 1,009 million tonnes containing 3.33 million tonnes of lead, 7.26 million tonnes of zinc, 16.5 million ounces of gold and 1,000 million ounces of silver. This paper describes the work to justify the installation of HPGR to process the crushed SAG mill pebbles. The SAG mill-Ball mill and Cone crusher (SABC) grinding circuit is an accepted grinding circuit to optimize power consumption relative to throughput. The installation of a HPGR to process the Cone crusher product is the next step in optimizing the power consumption relative to throughput. The concern expressed by some on not moving on this change in grinding circuit was the capital and operating cost of a HPGR. The pebbles from the SAG mill can be the more abrasive and are the harder particles of the ore. Goldcorp investigated the wear and processing costs of installing a HPGR to treat the crushed pebbles. The conclusion was the installation would be a very positive economic factor in the operation of Peñasquito. This is the first application of the use of HPGR to process crushed pebbles. Minera Peñasquito and M3 Engineering selected Polysius to provide a Polycom 2417 with twin 3,000 kW drives. A comprehensive test program at Polysius has shown for 7% higher circuit power it is possible to get approx 23% higher tonnage. This coupled with full utilization of the SAG and Ball Mill available energies and with proper control of the transfer size from the SAG to Ball mill circuit there is the potential to achieve 65,000 mtpd per line or a 30% total capacity increase. The cost of power for this increase in grinding capacity is 4.8 kWh/tonne.

Jan 1, 2010

By Ralph C. Flow

In Cleveland County, North Carolina, one and one-half miles south of Kings Mountain, Foote Mineral Company operates an open pit for the production of spodumene, feldspar, mica, and commercial stone. Spodumene concentrate is sent to Footers Sunbright, Virginia plant and to other customers. Exton, Pennsylvania and New Johnsonville, Tennessee plants produce lithium compounds sold to the oil industry for multipurpose lithium-base greases, to the metal industry as welding flux, to the air conditioning market, and to the glass industry. Ceramic grade spodumene, feldspar, and mica concentrates go to other processing companies from the Kings Mountain plant. Waste amphibolite is delivered to a neighboring quarry operation.

Jan 1, 1962

By F. Breu, R. Fraser, R. Lawrie

Diesel-powered underground mining equipment is generally accepted as the most productive, safest, and most efficient equipment used in underground mining operations. Widespread application of this equipment to underground mining is restricted, however, largely because of the difficulty of controlling the diesel engine exhaust emissions. This paper briefly examines control devices currently available for underground application, and also discusses the theory and mechanics of controlling diesel emissions with particulate traps and filters.

Jan 1, 1988

By B. R. Waples

The first reaction in organizing a project of magnitude is that it's the same as smaller projects -- just bigger. This is not totally correct. The industry's record of completing big-money jobs on time and within budget is not outstanding. From a personal point of view, my question is: What is the project size at which controls are lost? Is it controls? Is it the number of pieces of equipment? Is it the number of decisions to be made? The slowness of communications? Or is it a combination of all of these? In working on multimillion-dollar jobs, the percentage of overrun seems to be lower or show an underrun when the following basics are followed: 1) Preplanning is intensified 2) Data gathering is complete 3) Approach is optimized 4) Planning is realistically scheduled 5) Changes are minimized 6) Decisions are expedited

Jan 1, 1982

By W. M. Luff

The Brunswick No. 12 Deposit is a large polymetallic massive sulphide deposit, occurring in Ordovician age rocks of the Tetagouche Group. Silver is contained within the sulphide zones and economically it is the second most important commodity produced. Brunswick is one of the largest silver producers in Canada. The distribution of silver within the mine is presented, with examples from various levels. The concentration of silver can be shown to be related to both stratigraphy and structure. The mineralogy of silver in mill products is also presented.

Jan 1, 1986

By William R. Oakley

In order to best-discuss the met spar industry let me take the liberty to review our involvement, that is, my company's. Our organization has been involved in the fluorspar industry for approximately thirty-five years. We started our activity in Western Kentucky as a mining company and a beneficiator of spar, that is, grinding and grading. After a few short years, the mine became contaminated and rather than invest in a flotation plant, the property was sold and our spar activity was moved, primarily to Mexico. It was decided not to establish ourselves as a Mexican corporation, so, it was necessary to take the position of backer-financier of numerous mining operations. We served in this capacity for quite some time. We also built processing plants on the border in Texas, that is, sizing, grading, etc. in order to market into the steel industry. In 1957, generally speaking, fluorspar for the steel industry was purchased as gravel fluorspar with a maximum of 10% -1/16". The price of this material was $23.50 to $24.00 per ton f.o.b. railcar at the Rio Grande Crossings and about $26.00 or $26.25 f.o.b. barge, Brownsville, Texas. Usually the material was purchased on an effective basis. As you know, 2-1/2 times the silica total, subtracted from the total CaF2 gives the effective calcium fluoride. This was normally the extent of the chemical specifications. Consequently, material was shipped with no regard whatever, to anything other than effective units. The variations in material was absolutely unbelievable. In addition to this, quite frequently, cars were shipped, as they say in the industry, topped. This being, good material placed in the top of cars or barges over bad or low grade. The entire shipment may very well have met the effective unit spec, but the complete imbalance of the sub grade vs. the high grade more or less guaranteed that the consumer was probably using a great deal of low grade and therefore, his usage had to be way higher than it should have been. He came to the conclusion, that because of these conditions and the new technology developing in the steel industry, it was just a matter of time that the entire raw material industry would have to improve. Rather than spend our efforts directed to a substitute flux, we put together a sizing and grading plant in order to ship a controlled crude product, with independent laboratory analysis confirming size and quality. The age of control was started. We began shipping 70 to 72-1/2, 80 and 85 effective with sizing 1/2" by 2", 1" by 3", and 2" by 5" with absolute control on the amount of fines. A material with no fines was a premium product. Incidentally it sold for $24.50 -60 effective up to $28.50, $29.50 for 80 effective.

Jan 1, 1978

By R. L. Garrett

The quality of mineral additives used in a drilling fluid (mud) can dramatically affect the fluid's properties and the overall cost of drilling an oil or gas well. The principally wed minerals are bentonite, barite, barite/hematite blends, and hematite alone. The high specific gravity minerals, barite and hematite, are used to increase drilling fluid density. Bentonite clay is used to increase drilling fluid viscosity and gel strength and to provide a low permeability filter cake. A multimillion dollar investment in a well and the safety of the personnel on the drilling rig can depend on how effectively these mud additives perform with other constituents in the mud. This paper points out effects caused by small amounts of certain carbonate and sulfide mineral impurities in barite or hematite and how polymeric extender additives in bentonites contribute to unpredictable behavior of a mud. Effects like these are the reason oil companies using these materials sometimes set their own quality standards beyond those already specified in APZ Spec. 13A. Also discussed in this paper are the current standardization activities of API Committee 13 on these minerals.

Jan 1, 1988

By J. H. Calder, J. C. Hower

Three lithotypes of Phalen coal from Cape Breton County, Nova Scotia, Canada, were subjected to a modified Hardgrove grindability index (HGI) test. The testing scheme differed from conventional (ASTM D-409) Hardgrove testing by, in one case, repeating the test three times prior to removing the -200-mesh fine coal from the Hardgrove mill, and, in a second test, removing fines after each of three successive Hardgrove tests. Only the first stage of the latter testing scheme actually conforms to the standard HGI test. All processed samples were analyzed petrographically by a combined maceral/microlithotype analysis. The increase in the percentage of coal ground to -200 mesh increases through the 60- to 180-mesh fractions for each of the lithotypes for the following two apparent reasons. First, with progressive grinding, more of the oversize material is close to 200 mesh (75 µm), creating a "pool" of particles ready to be ground to -200 mesh, and, second, the removal of fines from the system at each step eases the grinding at the successive step. The fines retained system shows the influence of buffering of further grinding by the particles retained in the grinding mill. The Phalen lithotypes and the series of Central Appalachian coals, evaluated previously by Hower and Wild (1994), differ in that an increase in vitrite and a decrease in trimacerite is observed in successive -200-mesh fractions in two of the Phalen lithotypes. This is the opposite of the trend observed in the slightly lower-rank Central Appalachian coals.

Jan 1, 1998

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 Alban J. Lynch, Khairun Azizi

Education and research have always followed production in the mineral industry. Almost all of the leading mineral education and research units in the world today are in developed countries which had strong mining industries created during the 19th and 20th centuries to meet the demands for minerals due to the Indus- trial Revolution. It is in those countries where the main advances in mining and metallurgical technologies have occurred. But it is in the developing countries, often with traditions which have not favoured engineering initiatives, that the mineral industry is growing. Legislative changes and high exploration expenditures in many of those countries are of such a nature that many mineral discoveries will be made and mines and plants built in them during the next decades. Developments must be accompanied by increased activities in education, research and technology transfer in mining and processing, particularly those which are computer based. Malaysia is a developing country with the objective of achieving developed status by 2020. It has a short history of tertiary education and industrial research and a growing mineral industry. It is now building the education and research programs which will give strong support to its mineral industry. The progress which is being made in the computer based components of these pro- grams, and the factors which influence them, are discussed.

Jan 1, 1996

By D. Craig Camp

Microtunneling has successfully completed both horizontal and vertical curves. This paper covers the historical development of curved microtunneling and a description of one microtunneling project. The completed microtunnel is used for electrical transmission in Japan. The crossing had several concerns including right of way, social disruption, obstructions, the cost of intermediate shafts, and political restrains. In order for this drive to meet all of the imposed restrictions, four horizontal curves and one vertical curve were planned and executed in accordance with the design. Iseki Poly-Tech of Tokyo, Japan designed and built the microtunneling machine to meet the project requirements. Curved microtunneling has been successfully used on fourteen projects in Japan. The reason for a curve has been that the project could not be rerouted, short straight drives could not be used to negotiate the curve, or the project’s social and environmental conditions required a curved tunnel. The following table (Table 1) includes summary information on 14 curved microtunnling projects that have been successfully completed in Japan. The first column is a reference number. Columns two through four include basic project information. The fifth column is the total project distance completed by microtunneling. The sixth column is the project’s microtunneling duration. The seventh column is the machine type and size. All of the machines listed are manufactured by Iseki Poly-Tech of Tokyo, Japan. The size is the internal concrete pipe diameter; all of the projects listed were completed with Japanese standard concrete pipe. The eighth column contains a general description of the soil. The soil type and blow counts are approximately equal to ASTM D 2487 standards. The ninth column lists the radius of the curve and the span distance or the distance microtunneled that included the curve. The radius of a vertical curve is denoted with a “VR”, a span with both a left and right hand curve is denoted with a “S”. Other significant first events are also noted in this column. The first curved microtunneling project was completed in 1982 using a conventional microtunneling machine with standard Japanese concrete pipe and a very long radius curve while maintaining grade for the gravity sewer. The second curved microtunneling project included multiple radii curves, all in the same direction, on a single drive. In 1989, on the fifth curved microtunneling project, a “S” curve was successfully negotiated. On the seventh curved microtunneling project, completed in1995, a tight radius curve was negotiated. In 1996, the eighth project included a vertical curve. The thirteenth curved microtunneling project, completed in 1997, was the first project to utilize a microtunneling machine specifically designed to negotiate curves. The fourteenth curved microtunneling project was the accumulation of all

Jan 1, 2001

By Benjamin C. B. Hsieh

Many processes in the hydrometallurgical and chemical industries require the separation of dissolved material from suspended solids. Counter current decantation (CCD) with thickeners is one of the methods generally used. The process engineer needs a quick and accurate CCD calculation method. Several theoretical 1-12 CCD calculation methods are available in the literature . The simultaneous 1, 2 equation method for a complex circuit as used would take too long to solve the problems. Approximate equation method1 is not accurate and is for simple cases only. A shortcut method developed by Counselman3 contains no mathematical equation, and thus is not suitable for computer programming. Based on Counselman's method, Woody4 derived two simple equations in terms of percent soluble loss for two typical examples. Scandrett5 included a term for mixing in his formulas. This mixing efficiency was defined by Murphree6. Another method which depends on making volume calculations instead of using weights is presented by Mastin8 and Cahalan9. None of these methods is related to dissolution and pre¬cipitation reactions. Chen 10,11 demonstrated his methods for counter current leaching. His results are calculated from the general solution of a derived linear difference equation for constant underflow, and from the solution of a derived non-linear Ricatti difference equation for variable underflow. This paper concerns derivation of a general equation for CCD washing with provisions for adding and withdrawing the streams, and for leaching (dissolution) or precipitation reactions. These equations take several forms depending on the input information available. A set of simplified equations for continuous counter current washing and leaching is derived for determining:

Jan 1, 1972

By Roland W. Rammler

In recent years, the crude oil reserves of the world have increased at the same rate as the consumption. A Consideration of the global figures suggests that adequate supplies of petroleum will be available during the next decades. On the other hand, it in a fast of economic and political significance that the reserves in the industrialized countries increase much more slowly than in the developing countries. In Western Europe the reserves have even decreased. At the present time, about 70 % of the petroleum reserves of the world are in the Middle East and in Africa in regions in which political arises are prevalent or impending. For the industrialized countries, the discrepancies between the consumption and reserves in various regions of the world are a strong urge to investigate whether oil can be recovered from other sources. The situation will probably not be changed to a large extent by the discovery of oil in the north of Alaska. The main starting materials for the production of synthetic crude oil are coal, oil shale and tar sand. In North America, where the consumption of petroleum increases more rapidly than the reserves, there are enormous deposits of each of the three materials. This fact is another incentive toward the utilization of these unconventional oil reserves, which provide a reliable basis for a supple of energy for a long time to come.

Jan 1, 1970

By K. K. Bhattacharyya

In the Gulf Coast area lignite deposits occur in Texas, Louisiana, Arkansas, Mississippi and Alabama. Lignite has been mined in Texas since the early 1800's reaching a production of over 900,000 metric tons (1 million short tons) in 1910. With the availability of inexpensive oil and gas, production fall to as low as 16,000 metric tons (18,000 short tons) by 1950 (Henry, 1976). With the advent of the oil and gas shortage in early 1970, lignite production began to increase again. The purpose of this paper is to discuss the geotechnical considerations of mining lignite in the Gulf Coast area, particularly Texas and Louisiana. Lignite deposition occurs in unconsolidated sand, silt and clay environments. Extensive sand units saturated with water may be present within the potential mining depths. This paper describes the geotechnical considerations for designing a surface mine in this geographical area. These factors include geology, hydrology, mining method, and equipment utilization.

Jan 1, 1982

By A. Acar, E. T. Tuzcu, Y. O. Vural

"In order to sustain the operations in chromite processing plants, due to concentrate selling cost, plants are in need of optimization in terms of capacity and recovery increase. In this study, DAMA Engineering carried out a methodological study for the purpose after a detailed sampling campaign in a plant which is situated in one the main chromite zones in Turkey; 1 The current status of the plant was investigated quantitatively with the bottlenecks, Plant overall efficiency in terms of recovery, Efficiencies of the particular equipment (mill, screen, gravity circuit), 2 A new circuit was proposed with the available equipment, 3 The new circuit that is product of modeling and experimental effort, was evaluated quantitatively as if it is a running plant, After 4-5 months continuous effort, the capacity of the plant was almost doubled (37 tph to 70 tph) and the plant overall recovery was increased from 48% to 63% by grinding adjustments and additional shaking tables theoretically. It was shown that the plant may move into profit with the minimum amount investment using readily available system. INTRODUCTION TO THE CURRENT PLANT The objective of the study is to increase the capacity and recovery of the chromite plant owned by Kurmel Group, Akmetal Inc. The complete study is given elsewhere (DAMA, 2016). The plant is situated in one of the main chromite zones in Turkey; Aladag. The current capacity of the plant is around 35 tph and the overall recovery declared by plant engineer is around 47 %. The chromite plant mainly has 3 units; crushing, grinding and gravitational circuits. The crushing circuit has 3 stages; a jaw crusher, a secondary cone crusher and a tertiary cone crusher operating in closed circuit with a vibrating screen with the aperture size of 15mm. In grinding circuit, a rod mill (2.44 6m x 3.6) and a ball mill (2.13 x 2.3m) are used for primary and secondary grinding, respectively. Derrick screens are used for the size separation. Additionally, for the size classification of the system, hydrosizers are used and each size fraction is sent to the shaking table sets. The middling product of the tables is subjected to re-grinding with a ball mill with the dimensions of 2.1 x 2.9 m. The capacity and the recovery are affected by several bottle necks; hydrosizers’ pure classification, primary/secondary mill power vs capacity problems, re-grinding product’s high slime content and so on. These combined factors made the plant to run in low recovery and capacity. Hence, DAMA was asked to make a study to investigate current status of the plant and propose a new solution to increase capacity and recovery of the plant. The conceptual flowsheet of the circuit is given in Figure 1 below."

Jan 1, 2017

By J. S. Anderson

Size reduction models of cone and impact crushers have been developed using Whiten's generic computational structure for the description of crushers. They incorporate a laboratory single particle breakage test and the t-family of curves to describe the breakage behaviour of the feed ore. A quantitative model of 7-foot cone crushers has been developed, based on surveys of Svedala (Kobe) and Nordberg machines. Survey data on a Canica vertical shaft impact machine have been used to validate the impact crusher model. Given the crusher operating conditions, such as tonnage, feed size, set and liner condition, or rotor speed and radius, plus breakage information on the feed, the models provide good predictions of product size distribution, and appear to be robust over a wide range of conditions. They are incorporated in commercially available computer simulation packages.

Jan 1, 1998