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By E. Robert Kiehl

In the early days of the United States, gypsum was most commonly used for the manufacture of plasters with energy being used for quarrying, grinding, and calcining of gypsum rock. With the dramatic switch to gypsum-drywall construction after World War II, the energy usage per ton of rock processed increased more than threefold, and with the rapid growth of the construction industry, the total energy consumption in gypsum-board production alone increased eightfold during the period from 1940 to 1973. The gypsum industry was one of the first to recognize the need for energy conservation and has voluntarily reported its progress to the Federal Energy Administration for the past several years. Efficiencies in the use of energy have resulted in decreasing the unit consumption an estimated 10 percent during the past six years. Improved combustion efficiencies, optimum operating conditions, more liberal use of insulation, and heat recovery will all contribute to the gypsum industry's goal of using less energy. Gypsum products today are vital to over 85 percent of new housing construction in the United States.

Jan 1, 1978

By Charles Rubin

Mining is a capital- and labor-intensive business, and profitability often depends on the ability to squeeze maximum efficiency out of every piece of equipment to achieve safe production. This means keeping every mechanized drill, loader, truck and bulldozer operating at all times, and having a system to coordinate the movements of people and personnel. Mines often use wireless radios to connect equipment with management systems. But growth and changes in a mine?s profile over time can require upgrades to the wireless network. In its openpit gold mine near Carlin, NV, Newmont Mining Corp. has recently upgraded to microwave radio systems to increase bandwidth while maintaining round-the-clock uptime on its wireless network. For many of its operations around the world, Newmont uses Minestar, an operational control software system that allows administrators to dispatch equipment operators and use GPS to track the precise position of every piece of equipment in an operation. Each of the approximately 150 pieces of equipment at the mine has a radio on board. These radios connect to a network backbone that carries information between the equipment and the mine?s operations center. When traffic began to bog down on this network, Newmont upgraded to Exalt microwave backhaul systems to carry dispatch, inventory and control information throughout its operation.

Jan 4, 2010

By N. ?peh

The purpose of the paper is to present a way of assessing nonrenewable lignite resources by means of sustainability indicators. An introductory presentation of the origin and characteristics of the discussed nonrenewable natural resources is followed by the study and analysis of separate sustainability indicators. Out of many, only the ones that would directly relate to the explored coal deposit were studied. Some different viewpoints such as economic, social and environmental were assessed inside the studied landscape structure and in relation to other provincial resources using the indicators that are closely linked with the explored lignite reserves. Exploitation of coal as an underground nonrenewable natural resource, has been taking place in the ?alek valley for more than 120 years. However, about 60% of the coal will still be left underground since not all coal will have been extracted when the mine closes. According to the regional and wider national strategic goals concerning the use of natural resources and electricity production in the future, the sustainable aspect of the exploitation of the geologically well explored reserves is emphasized in the paper. Finally, we have tried to evaluate the role and the meaning of the studied underground natural resources for further sustainable development of the ?alek valley and placed stress on the most questionable spheres that should be considered preferentially.

Jan 1, 2007

By B. J. Arnold

Coal blending inherently means homogenizing a mixture of coals so that the properties of the blend meet some specifications for maintaining power plant performance and emission requirements. In practice, however, coal blending is, at best, coal mixing. The degree of blending sophistication required depends on the reason for coal blending in the first place. If it is to maintain fuel characteristics that will diminish the chance of slagging and fouling, then some swings in variability may be tolerated at some power stations. However, if emissions limits are the issue, then more sophistication may be needed. Emissions limits are becoming stricter with requirements to meet averages for shorter time frames (hours and days instead of weeks and months). These restrictions require closer control over the quality of the blend being fed into the bunkers at the station. Even scrubbed units should have a consistent quality of fuel as feed so that sorbent additions can be minimized. To meet these challenges, engineers must consider available equipment and control techniques and the properties of the parent coals when evaluating new blending systems.

Jan 1, 1994

By Robert B. Hopler

Explosives research and development has historically been motivated by coal mining. Whether to solve safety problems or to improve productivity and cost, the result has been the same: better explosives products and initiation systems. Today, this process continues at an accelerated pace due to the tools presently available to the explosives and mining industries. Background Explosives have been used in coal mining since the industry's earliest days. Black powder, introduced into metal mining in 1627, undoubtedly was introduced into coal as soon as a need to replace pick work was apparent. Until the invention of the safety fuse by William Bickford in 1832, the only initiation methods available were the straw, quill and miner's squib. Disastrous explosions underground in England brought about studies on their possible causes (Atkinson, 1886). The studies showed that, while explosives contributed to the accidents, the real villain was coal dust, since that was the agent that transmitted the disaster throughout the mine workings. To improve underground safety, research was applied in an attempt to make explosives that could be safely fired in a methane air atmosphere. The Prussian government was apparently the first to establish a testing station for coal mine explosives. This occurred in 1885 (Guttmann, 1909).

Jan 1, 1993

By Robert J. Auber, Thomas R. Scotese

The West Leg Interceptor is part of a new sanitary sewer system in the southwest suburbs of Cleveland. The first two construction contracts were excavated in glacial soils varying from hard tills to pressurized silts and flowing sands. These soil and groundwater conditions were locally problematic during shaft and tunnel excavations and final lining construction. A variety of solutions were developed primarily during construction. During the WLI-1R Contract, subgrade pressures, continued ground losses, and displacements necessitated extra eductor wells and modified inverts for stabilization of shafts. At the WLI-2Contract, one shaft excavation in similar ground required only one extra well. In the WLI-1R tunnel, localized inflows of groundwater, silt, and sand through the geotextile fabric were stopped by cement grouting. In one WLI-2 connector tunnel, damage to the TBM flood doors combined with wet, flowing silt and sand led to ground losses, surface settlements, plugging, patching, and chemical grouting. The concrete lining in the main WLI-2 tunnel required remedial work to improve watertightness at joints.

Jan 1, 1999

By Dennis C. Martin

Construction of the Cerro Colorado on-off leach pad in northern Chile required about 3 Mm2 (32.3 million sq ft) of fill over an area of about 600,000 m2 (6.5 million sq ft) in irregular terrain with relief of up to 40 m (130 ft). Earthwork construction was completed in about six months using mine waste, placed in 4 to 6 m (13 to 20 ft) lifts with mine haul trucks. The lift thickness was reduced and the compactive effort increased in the upper 10 m (33 ft). This was done to develop a mat for additional resistance to possible differential settlements due to the modest density of the fill and dynamic (earthquake) conditions. A single 2-mm (80-mil) high-density polyethylene (HDPE) liner was used below the leach pads. This was protected from the loading and unloading equipment by bedding and cover systems. It consisted of screened sand, gravel and silt as the bedding and cover layers and a heel of screened gravel and primary crushed low-grade ore.

Jan 1, 1995

By N. S. Tombs

This paper presents the experimental results of an ongoing investigation into various properties related to the performance and durability of concretes made using existing and new cement replacements. The process of cement and concrete production is investigated focusing on product performance and environmental performance. The overriding factor for the progression of a material will be product performance however; each material selected will have many intrinsic environmental benefits. The study combines Ordinary Portland Cement (OPC) with each cement replacement candidate using the most common replacement percentages, 10, 20, 25, 30 and 50 percent. A 35N/mm2 concrete is then prepared and analysed in the fresh and hardened state. In addition, a chemical and physical analysis of each replacement material has been performed and results compared to the control samples containing OPC only and Ground Granulated Blast Furnace Slag (GGBS) as a replacement. The results show that in their present form the replacements used in this research do not compare with the strengths achieved by the controls. The right balance of chemical composition and particle grading needs to be achieved to produce a realistic replacement material. The processes required to achieve this must strike a balance between monetary and environmental cost.

Jan 1, 2006

By Robert S. Neil, O&apos

The basic transportation planning process consists of: 1. Inventories and analyses of existing conditions. 2. Estimates of future growth. 3. Determination of future travel demand. 4. Testing alternative systems to satisfy future travel demand. The many modeling techniques used in the transportation planning process are well known, commonly accepted, and thoroughly described in readily available literature. This paper will concentrate on the fourth step of the planning process, specifically the development of alternative systems for testing, and will discuss some of the factors which should be considered during the development of alternative systems. There are many factors which require consideration and which have a bearing on the configuration of alternative test systems. These comments will be limited to the influence of geographic, demographic, geologic, and economic factors. Although addressed separately, the four are to a great extent related and have a significant effect on each other. The objective of examining these factors during the early phases of system planning is to assure that more detailed corridor studies will not be stymied by considerations which could have been anticipated and accommodated at an earlier time. It is particularly important that feasibility of construction be assured before test systems lead to corridor decisions and accompanying commitments to

Jan 1, 1974

By W. Kuckshinrichs

Metallic raw material flows are characterized by a complex global network of producers and consumers, as well as by a multitude of ecological, economic and social impacts across national boundaries and on different scales. This leads to the need to develop methodologies, which allow identifying obstacles that prevent metallic raw material flows to contribute to sustainable development. From a scientific point of view CRC 525 (Martens 2003) has developed an holistic indicator set consisting of approximately 80 different indicators. This set is taking into account the multi-dimensional character of sustainable development. Moreover the indicators reflect different system boundaries according to different actor levels and decision contexts. The full indicator set is important in scientific considerations and suitable for scientific awareness creation. However, to fulfil the function of a decision support approach for political and economic decision-makers some modifications are of central concern. At first a reduction of the full indicator set by selection of core indicators enables decision-makers to deal with complex issues of contrary economic and societal protection targets. Secondly, as thresholds of indicators justify societal call for action, they are discussed against its political or scientific origin. The proposed methodology is exemplified by indicator-based studies of the material flow of aluminium.

Jan 1, 2003

By S. D. Van Nort

Editor’s note: This is the first of two MINING ENGINEERING articles about the Grasberg deposit. The second, focusing on open pit mine development, will appear in the April issue of the magazine. The Grasberg porphyry copper-gold deposit of Freeport Indonesia Inc. lies within the Ertsberg Mineral District in central Irian Jaya, Indonesia. The Grasberg deposit was discovered during a drilling campaign initiated in the mid-1980s. Production at the open pit de- posit commenced in December 1989. The Grasberg copper-gold ore body is contained within a young igneous complex of dioritic composition that intrudes limestones of the Tertiary New Guinea Group. Alteration is typical of porphyry copper deposits worldwide except that higher grade primary chalcopyrite with significant gold values is associated with a centrally located zone of strong quartz stockwork. Irian Jaya comprises the western half of the island of New Guinea. The Ertsberg District lies 70 km (43 miles) inland from the Arafura Sea at an altitudeof3500 to45OOm (11,480to 14,764 ft). It straddles the Papuan fold belt. This belt forms the east-west trending chain of mountains that extend the entire length of New Guinea and is the site of numerous mineral districts.

Jan 1, 1991

By Roger E. Melley

Since startup of the Syncrude Canada Ltd. (SCL) oil sands facility in northern Alberta 15 years ago, numerous improvements have been made in the ore conveying system and equipment. The unique nature of the material conveyed coupled with the wide range of environmental conditions encountered results in a number of unparalleled challenges. Most of the improvements have been brought about through the use of detailed field evaluation. Numerous publications are available that detail the various aspects of conveyor technology, and a significant list of papers are presented each year adding to the knowledge in this field. In the area of power formulae in the mid- 1970s, there were two major sources for use in the design of the SCL conveyors: the Conveyor Equipment Manufactures Association Handbook, 1988, and DIN Specifications 22101: Belt Conveyors for Bulk Materials, 1982. These sources were supplemented by the knowledge of the belt and conveyor equipment vendors and from the general literature. The SCL design was based on the CEMA formula. However, it was accepted that this empirical approach had been developed for use with more conventional materials in more reasonable climates. To accommodate

Jan 1, 1993

By Staff

GENERAL DESCRIPTION The Lucky Friday mine is located in Mullan, Sho-¬shone County, Idaho. The mining method is horizontal slice cut-and-fill (with timbering for support or un¬timbered) using hydraulic sand. Cemented sand fill at a 1:17 ratio is used in sill pours and at a 1:7 ratio for the final 152 mm (6 in.) capping in successive stope floor pours. Annual production with 100% cut-and-fill mining is 167 829 t (185,000 st). The average depth of mining is 1296 m (4250 ft) and the average travel time to the stope is 45 min. GENERAL ORE BODY REQUIREMENTS AND LIMITATIONS Size The ore body is 396 to 488 m (1300 to 1600 ft) long on strike, 1421 m (4660 ft) on dip, with an average width of 2.3 m (7.5 ft). Dip varies from vertical to1.2 rad (70°) Ground Conditions, Ore Value, and Production Requirements The ore body contains quite strong argentiferous galena and quartz. The hanging wall and footwall are strongly sheared and fractured. Ore value is $211/t ($192/st).

Jan 1, 1982

By Steven R. Wardwell, Gerald G. Stokes

INTRODUCTION A compaction grouting program to control ground loss, and to minimize surface settlement, was developed for the West Tunnel of the Phoenix Storm Drain Tunnels. The West Tunnel was 4,200 m long, 7.56 m in excavated diameter, and was excavated with shallow cover through the central Phoenix business district. The tunnel could not have been successfully excavated without the compaction grouting program. HISTORY After heated political debate over a ten year period, the Arizona Department of Transportation (ADOT) was granted approval to build the Papago Freeway, an extension of Interstate 10, through central Phoenix. To comply with environmental constraints, a portion of the Freeway was depressed, requiring an excavation 10 meters in depth, thus intersecting surface run-off from the northern section of Phoenix. This required that ADOT and Project Design Consultant, Howard, Needles, Tammen & Bergendoff (HNTB) design a drain system to collect run-off and transport it approximately 4 kilometers to the Salt River through the City of Phoenix. Tunnels were chosen for the main discharge conduits because depth and location of the system made cut and cover construction impractical. A contract for construction of the tunnels was awarded to Shank-Artukovich-Ohbayashi (S-A-O) on May 24, 1984.

Jan 1, 1987

By Eugene V. Cilento, George B. Georgellis

The hypothesis that freshly-sheared quartz makes it more reactive in lung tissue than aged quartz was tested by its ability to stimulate superoxide anion (02-) release from single adherent pulmonary alveolar macrophages (PAM). Fresh quartz was prepared by grinding for 30 min and then used within 2 hr, while stale quartz was from the same stock but aged 15 days prior to use. Also, dipalmitoyl lecithin (DPL), the major constituent of lung surfactant coating the alveoli surfaces, was coated onto the particles. Release of 02- was measured after 40 and 180 min of direct contact with quartz dust (225 µg/ml). Fresh quartz was more reactive than aged quartz, as indicated by the 78 and 63% increase after 40 and 180 min, respectively. A time delay and suppression of 02- release was observed in the ability of the DPL- coated fresh or stale dust to stimulate PAM. These results supported the hypothesis that the natural process of surfactant coating of inhaled particles in the alveoli may play a role in their phagocytic removal by PAM.

Jan 1, 1991

By Weston Bourret

The need for wartime supplies of uranium for the Manhattan Project prompted a 1944 study of uranium in South Africa. Uraninite had been reported by R.A. Cooper in 1923 in a Witwatersrand heavy- mineral concentrate, and the search for uranium, therefore, included the district's 30 operating mills. The method of investigation was simple: take bulk concentrate samples from the Wifley tables and determine their mineralogy. Samples were taken on a daily basis, although weekly composites also were taken of some mills. In 1944, most mills had simple gravity circuits and produced (I) a gravity concentrate, and (2) an all-slime [-75 pm (-200 mesh)] product. The tonnage throughput was known, and from that, head assays could be calculated. Concentrate samples were sent to the United States for chemical analyses. A Geiger counter set up in a Johannesburg hotel room provided preliminary data. The early data showed uraninite to be widespread. Microscopic, mineragraphic, and siezing tests were all under- taken in Johannesburg. Ultimately, tests led to a high grade (+90%) uraninite concentrate. Platinum and other heavies were the impurities. In seven months, the investigations had reached the stage where it was possible to forecast an annual production of 5.4 to 7.3 kt (6,000 to 8,000 st) of U3O8. The estimate is still realistic. Additional details are found in Bourret (1981).

Jan 1, 1991

By Osamu Shoji, Mamoru Kato

In order to continue improving the quality of telecommunication services to meet the expectations of the people and to increase reliability in the case of emergency such as disasters, Nippon Telegraph and Telephone Public Corporation (NTT) is now constructing cable tunnels which connect main urban telephone offices. However, almost all the large cities in Japan are built in river deltas, so that their chief underground features are low strength fluvial deposit and a high ground water level. In this saturated soft ground, the ground surface at an installation site has occasionally subsided through deep excavations for cable tunneling construction. As these settlements have sometimes caused accidents, especially in densely populated large cities, NTT has made much effort to avoid such accidents. These accidents have occured mainly in flexible sheeting due to its inward movement. Therefore, after the investigation into forecast method of sheeting deflection with accuracy, NTT has reserched a system which forecasts ground surface settlements. This paper describes an outline of the ground settlement forecast system and practical example on the site.

Jan 1, 1979

By Donald E. Scheck, Syed F. Abbas

Public domain ventilation simulation programs have been well accepted by the mining engineers, but preparing the input and interpreting the results are labor intensive tasks. High performance personal computers and versatile CAD packages provide the means to quickly create the network and display the results. The enhanced simulators work from computerized as-mined map, the projected mine layout and timing maps. Using on screen displays of these maps and the snap-on feature of AutoCAD, the planner designates nodes in the ventilation network, connects them into branches and selects the branch characteristics from a side bar menu. The color coded ventilation network appears with the parameters shown along each branch. The software then calculates the length of airways and computes the branch resistances where needed and converts the input into the required format and passes the data to the Pennsylvania State University or U.S. Bureau of Mines ventilation programs. Output is available in graphical as well as report format. The color coded graphs include pressures at the nodes and flow quantities on the branches. Since the networks come from the mine maps, the ventilation displays are to scale and can be plotted separately or superimposed on the mine maps.

Jan 1, 1991

By J. Craig Green

Companies mining for coal, oil shale, and minerals in the western US must often complete extensive geotechnical studies to satisfy federal and state regulations. The modern mining process is further complicated by the legal problems and liabilities associated with mineral rights and land leasing. Yet the study of water rights-unique to the West is often incomplete or ignored until the latter stages of mine planning. Water rights in the West are not adequately understood by many mining companies and their geotechnical consultants. Some firms, headquartered outside the western US, have not had to contend with the water supply problems of a semi-arid region. Water problems encountered by eastern mining companies, for example, are primarily water quality, drainage, and flood control. Even when water quantity is a problem in these areas, ownership and/or use of it is governed by entirely different legal and administrative concepts than in the West. Both legal and engineering issues have to be considered when studying western water rights. Legal issues, such as existence and title, must be addressed to insure that a particular water right is properly established and maintained. The exercise of a water right, however, often requires engineering analyses that focus on preventing injury to the properly established water rights of others.

Jan 8, 1981

By Patrick J. Coughlin

Shortly after Asarco Inc. purchased the Ray Mines Division from Kennecott in 1986, the company began an expansion program to increase copper production. The Bechtel Corp. oversaw engineering procurement and construction management for a new in-pit crusher, overland conveyor system and concentrator facility. Construction started in May 1990 on these facets of the expansion project. The concentrator was commissioned in February 1992. The Ray concentrator uses a single-line, semiautogenous grinding circuit (SAG) with a design through¬put of 27 kt/d (30,000 stpd). In the early 1960s, Kennecott conducted pilot plant grind tests of Ray mine ores to determine their amenability to SAG and autogenous grinding methods. Those tests, though, were not followed up. During 1973 and 1982, Kennecott conducted additional pilot testing on some of the softer ore types. In 1989, Asarco ran a final series of SAG pilot grinding tests at Lakefield Research, which became the basis of the new Ray concentrator grinding circuit. Even though pilot test work demonstrated that some of the Ray ores gave satisfactory results during the autogenous grinding tests, the SAG option was selected for the primary comminution device. Due to the wide range of mineralogies encountered in the Ray ore body, selective mining and blending of these ores would be required to achieve the necessary production efficiencies and throughput rates using an autogenous grinding circuit.

Jan 1, 1994