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By Larry Murphy, Mohammad R. Jafari, David M. Giel, Sharat K. Kalluri

"Built in 1940’s to provide a key roadway arterial between New York and Boston, the Heroes Tunnel is the only highway rock tunnel in the state of Connecticut and is part of the Wilbur Cross Parkway. This 365.0 m long tunnel consists of two barrels, each with two lanes of traffic, and carries over 71,000 vehicles per day. For nearly 70 years, the tunnel has seen millions of vehicles pass through but time has taken its toll and now the tunnel lining, ventilation system and radial section joints are significantly deteriorated and in need of rehabilitation. Owned and maintained by the Connecticut Department of Transportation (CTDOT), CTDOT initiated a unique managed approach to mitigate the risk, social impacts and financial implications associated with rehabilitation of this tunnel. This new approach consists of performing field inspection and conducting a comprehensive study to explore six rehabilitation options, including construction of new tunnels and enlarging the existing tunnels. The main criteria for this study are: Impact on traffic and the resulting delay cost; Construction cost; Construction duration; and Construction complexity. This paper will present the results of the alternative study. PROJECT BACKGROUND Location and Importance Heroes Tunnel is located in the State of Connecticut within the Town of Woodbridge and the City of New Haven near the Town of Hamden border. Heroes Tunnel is the only true highway tunnel in the State of Connecticut. The tunnel is part of the Wilbur Cross Parkway (Route 15), a scenic connection between Hartford and New York. Originally constructed and opened to traffic in 1949, the tunneled portion of the parkway passes through the West Rock Ridge. The tunnel was originally named West Rock Tunnel, but was re-designated as Heroes Tunnel in 2003. Route 15 is a vital roadway within the State transportation infrastructure. In the vicinity of Heroes Tunnel, Route 15 carries approximately 71,000 vehicles daily. Locally, Route 15 provides access to residences, shopping centers, and points of interest, as well as other state roadways. Regionally, Route 15 connects New York to the Hartford area and serves as an alternate expressway route to I-95 and I-91. The tunnel is approximately 365.0 m long and passes through the West Rock Ridge. West Rock Ridge is an 11.3 km long rock ridge located on the west side of New Haven. A network of suburban streets abuts the mountain on all sides and a seasonal paved park road climbs to the crest of the ridge. Figure 1 depicts the tunnel topography and location."

Jan 1, 2016

By R. A. Metz, William H. Breeding

The remarks that follow are based substantially on experience covering 45 years, 80% of which has been in placer work, rather than on a review of available literature. Most commercial placers have been deposited by the action of water. The richer and more difficult-to-mine placers are those in the headwater areas where gradients are steepest. The most lucrative placers are generally in intermediate areas where volumes are greater, fewer boulders are present, and gradients are from 3% to 1-1/2%. The higher volume, lower grade placers are in the lower reaches of river systems where gradients are lower. Where gold-bearing rivers have discharged into the sea, wave action can concentrate values on beaches, past and present. Most of the rich, readily accessible placers were mined by our forefathers. Current opportunities exist: (1) in remote areas where infrastructure has been absent in the past, or development has been prohibited by adverse ownership - political or commercial; (2) in deposits that could not be mined by equipment available to our forefathers; (3) in deposits unidentified by our forefathers; (4) where the-price-of-product/cost ratio is substantially better than in earlier years; or (5) a combination of those factors. When I entered the placer business in the late 1930s, and subsequently, a prevailing opinion believed that glacial deposits should be avoided as irregular in mineral content and composition, and unrewarding to explore and develop; yet an operator has been mining a fluvio-glacial deposit profitably for the past 17 years. Rich buried placer channels, often called paleo-channels were worked in the last century, generally by hand methods, and under conditions that would be unacceptable today. Exploration and mining equipment now available make some of these channels attractive targets. Well-known examples are in California and Australia. The formation of a commercial placer requires a source of valuable minerals. Above primary deposits, there may be eluvial deposits formed by the erosion of gangue minerals and the concentration "in situ" of valuable minerals. Down slope from these deposits are the hillside or colluvial deposits, and below them are the alluvial deposits of redeposited material. Most of the great placer fields of the world are the result of several generations of erosion and deposition. Well-known examples are in California and Colombia. Gold is a very resistant and malleable material, and gold placers may extend for 64 or 80 km (40 or 50 miles) along a river system. Platinum is less malleable, but is very resistant to disintegration. Diamonds are extremely hard, and (especially gem diamonds) may be found over great lengths of a river system. Cassiterite is less resistant to disintegration, and tin placers seldom extend over two miles without resupply from an additional source or sources of mineralizaton. Tungsten minerals are generally more friable, and within a few hundred yards of the source disintegrate to the point that they are uneconomical to recover. Rutile, ilmenite and zircon placers generally result from the weathering of massive deposits, and may be encountered over extensive areas; most are fine grained and durable. What does a geologist or mining engineer look for in placer exploration? The old adage to look for a mine near an existing mine is still valid. You need a source of valuable mineral. Then you require conditions for concentration, which means a satisfactory gradient and/or other conditions that will permit heavy minerals to settle. Nicely riffled gravel, often called a shingling of the bars, is conducive to placer formation. Coarser gravel is logically associated with coarser gold. Excessive clay and/or high stream velocities in narrow channels can carry gold far downstream and distribute it uncommercially over a large area. When material is extremely fine, in situ weathering and concentration become more important. Placers frequently occur distant from lode mines, and one must remember that in a larger watershed the exceptional floods that occur once in a hundred or a thousand years can move great quantities of material long distances. The carrying power of water is said to vary with the fifth or sixth power of its velocity. I am not ready to disagree with Waldemar Lindgren and accept that many commercial placers are substantially enriched by the chemical deposition of gold from solutions; however, I have seen crystalline gold in clayey material quite distant from known sources of primary gold that is dif-

Jan 1, 1992

By Bing Wang, Jingli Fan, Qinying Song, Fengyu Li, Xian Zhang

"With the background of water shortages and serious water pollution, issues of water involved in energy exploration and utilization have become critical problems affecting urban water usage. In order to identify the relationships of the energy-water nexus, this paper characterizes the energy-water nexus literature using a bibliometric method and based on the Chinese National Knowledge Infrastructure database platform. The results reveal that 1) Scientific outcomes in this field have increased sharply since 2003, with a slightly higher growth rate than that of general disciplines. 2) China Water Resources, Yangtze River and Express Water Resources & Hydropower Information are the dominant journals, and the main research fields include industrial economics, environmental science, and management, among other disciplines. 3) Hohai University, the Chinese Hydraulic Engineering Society, the Institute of Geographic Sciences and Natural Resources Research, and the Changjiang Water Resources Commission are the main research institutions in this field. However, the proportion of publications of these institutions is not high, which suggests that there is no institution dominating this field. 4) According to the keyword analysis, the hot spots in this field include ecological environment, sustainable development, environmental protection, climate change, etc. Energy-mining related keywords have increased over time, implying that the energy-water nexus from the perspective of the energy exploitation industry can become a key issue. At the same time, the frequency of keywords related to sustainable development has been maintained at a high level, and the studies concerned with the impacts of climate change were introduced into this field relatively late. The conclusion of this study provides a foundation for a comprehensive understanding of the current situation as well as for further research in the energy-water nexus field.Introduction As an important strategic resource for national economic and social sustainable development, water has been increasingly focused on by the Chinese Government. Over the next decade, the total water demand of China will continue to grow steadily, which lead to a significant trend of increasing water consumption in the future (Zhang 2013). To reasonably exploit, utilize, conserve and protect water resources, the Water Law of the People's Republic of China was enacted by the members of the 9th National People's Congress Standing Committee in 1988 and after multiple revisions, the latest of which, in September 1, 2016, has involved water infrastructures in the national economic and social development plans of the government at all levels and regulated the rationale for water engineering construction. Thus, in the context of serious water shortages and water pollution, China’s government has taken several measures to make rational use of water resources."

Jan 1, 2017

By Melvin E. Poad

INTRODUCTION The placement of concrete by means of pumping is one of the fastest growing practices in the construction industry and is widely used in mining applications. In¬troduced in the United States in 1933, this method has been adapted to many aspects of the industry, especially where space for equipment is either limited or inaccessi¬ble. Concrete pumping offers many advantages over other methods of placement. Using pumping equipment, the concrete mixture can be transported in a single operation from a central mixing site to numerous forms in many remote locations, eliminating the need for rehandling the mixture and reducing the labor costs to a minimum. Pressurized pumping provides an extra mix¬ing and blending step, resulting in concrete of improved uniformity and greater density. In turn, this produces high compressive strength and increased durability. Various placement defects can be reduced or pre¬vented by pumping. The steady and even flow of the concrete minimizes the form distortion and delays caused by vibration problems that are common to fast dumping of the concrete mixes. Segregation, planes of weakness, bleeding, and surface faults are diminished considerably. Perhaps the greatest advantages of concrete pump¬ing are the distances and volumes that can be handled. Depending upon the equipment used, pumping rates of from 8 to 115 m'j/h (10 to 150 cu yd per hr) can be achieved, with a horizontal range of up to 460 m (1500 ft) and a vertical range of up to 140 m (450 ft). Theoretically, almost any concrete mixture could be pumped. However, consistency is an important consid¬eration for efficient operation. Mixes that are too wet, too dry, too hard, or poorly graded can cause difficulties that increase the costs. Similarly, mixes containing aggregate material that is over the maximum size or that is porous and highly absorptive can also result in diffi¬culties and increased costs. For the best efficiency, the mix formulation must have a well-graded sand and aggregate combination, with enough fines to provide flowability. If additional water is required for pumping, additional cement must be used to meet the design criteria of the structure. Each pump manufacturer can provide recommended mix formulations for the specific equipment furnished. Since the 1950s, many improvements have been made in pumping technology. Originally, only rigid steel pipe of 168 to 245 mm (6.625 to 9.625 in.) diam was used; today, both rigid steel pipe and flexible conduit are available in diameters of from 76 to 203 mm (3.0 to 8.0 in.). Improved pumps have been developed, and the introduction of power-coordinated booms has in¬creased the versatility of concrete pumping. The older and more conventional placement methods can no longer compete with the flexibility, efficiency, and econ¬omy of the pumping method, and continued research and development can only improve the system and expand its use throughout the mining industry. PUMPING EQUIPMENT The three major types of concrete pumping units currently available are the piston pumps, the pneumatic pumps, and the squeeze-type pumps. Table I provides a comparison of capacities, horizontal ranges, and vertical ranges for pumps of all three types. Piston Pumps The simplest of all concrete pumps are the piston¬type pumps; they are available from many manufac¬turers. As shown in Fig. 1, each unit consists of a

Jan 1, 1982

By R. Krishna, L. A. Kumar

The paper suggests a new empirical model for predicting mining subsidence. The parameters considered are Lithological Factor, which in this context meant percentage of sandstone, Rock Mass Factor (depending upon the RQD value of drill-hole cores), width: depth ratio and percentage extraction of coal. More than 250 drill-hole cores from seven longwall panels and 11 bord-and pillar (room-and-pillar) workings were analyzed from an extensive data bank of Singareni Collieries Company Ltd. (S.C.Co.), Andhra Pradesh, India. Excellent subsidence agreement was found with the suggested model.

Jan 1, 1993

By N. Djordjevic

Introduction The vibration energy that travels beyond the zone of rock breakage is wasted - all it does is cause damage and annoyance. Under favorable geologic conditions, this energy may travel many kilometers before it finally drops bellow the background noise level. This has forced the introduction of more restrictive limits to the allowable vibration levels. To maintain the profitability of a mine or quarry and to comply with environmental protection legislation, blasting needs to be performed in a more predictable way that will ensure that the final results are optimal in both mining and environmental terms. Minimization of ground and induced structural vibration is, therefore, a matter of good blasting practice -not just an attempt to avoid complaints from neighbors. A new approach to blast vibration minimization is presented. The method utilizes the existence of the local minimums in the frequency spectrum of single-hole blast vibration. The results are presented as a delay map showing maximum ground or structural vibration velocity for many combinations of interhole and interrow delays. A blast engineer can use this map to select an optimal combination of delays that will produce a low vibration velocity at a selected location and, at the same time, will be acceptable from the point of view fragmentation or muck pile shape. Response of structures A typical single-story building has two distinctive forms of vibration. The first form is a translatory vibration of the building superstructure (frame), and the second form is a flexural-bending vibration of the structural elements such as walls and floors (Siskind et al., 1980). Walls and floors will have several modes of oscillation. The most important is the fundamental mode of the vibration, as this mode will have the lowest frequency, the largest amplitude and will cause the largest deformations. The vibration of walls and floors is also a source of secondary vibration within a building, due to the movement of loose objects, e.g., furniture and wall fittings (Dowding, 1985). The subjective estimate of the amplitude of a vibration by the occupants of a house will be unrealistically high due to the effect of the secondary vibrations. It is now well recognized that human perception of ground vibration begins at levels that are far below those that will produce minor damage to the most fragile structures. In mining and quarrying operations, complaints regarding vibration levels tend to be determined more by human perception or annoyance rather than by observations of damage. Ground vibrations on the order of 0.08 mm/s (0.0032 ips) (Walter and Walter, 1979; Murray, 1987) can be felt, and they are often subjectively estimated to be about 100 times greater. Amplification of ground vibration in the structure depends on the amount of energy in the ground vibration spectrum that is in the vicinity of the structure's resonant frequencies together with the damping ratio of the structure at these particular frequencies. One way to avoid significant vibration amplification in a structure is to shift the dominant part of the ground vibration away from the resonant frequency range of the structure. The presented method allows for the selection of the optimum blast timing (interhole and interrow delay times) to minimize the resultant ground vibration amplitudes in a given frequency range. It also allows the selection of suboptimal, but still acceptable, blast delay times, which may be preferable from the point of view of overall blast performance. Determining frequency ranges of importance in structures In attempting to avoid amplification of vibrations in the structure, ground vibration amplitude of frequencies close to the resonant frequencies of the building needs to be minimized. The width of the frequency-minimization region is determined by the value of damping in the building. If the damping ratio is low, then the frequency-minimization region around the resonant frequency will be relatively broad. By shifting the dominant part of the ground-vibration energy into the frequency region much higher than the resonant frequency of the building (1.5 to 2 times), it is possible to achieve efficient vibration isolation of the building. In such cases, the structural dynamic amplification of ground vibration will be less than unity. The first step in this minimization process is the determination of the structural resonant frequency. From the frequency spectrum, it is possible to determine the resonant frequency of the structure. Sometimes the

Jan 1, 1998

By Stephen C. Tadolini, Thomas M. Barczak

Western mines have had limited choices for standing support. Wood cribs were often too soft and unstable. The introduction of the Can support in the early 1990’s provided a very effective alternative and remains the dominant form of tailgate support. Water-filled prestressing cells are now used to cap the Can and preload it to provide an active roof load. The Cluster Prop, consisting of three timber wedge props bundled together, provides more capacity than an equivalent sized Can support and improves transport efficiency. However, the Cluster Prop is less stable and does not maintain a consistent load throughout its loading profile. Pumpable roof supports are another alternative support, but they have not been proven in high deformation environments. Alternative supports are also being used in longwall recovery operations. These include the Rocprop and Omni Prop, which are extendable support systems. They also provide active roof loading which can be beneficial in these applications. Specialty supports, such as the Sand Prop and Spider Prop, have also been introduced into western longwall operations. This paper compares the performance characteristics of these various support systems.

Jan 1, 2005

International Minerals & Chemical Corp.'s New Wales operation near Mulberry, FL, is reportedly the world's largest concentrated phosphate chemical fertilizer and phosphate-based animal feed ingredients complex. Its latest expansion represents a $191-million investment. Two Northwest draglines were put to work at the operation early last year and, according to a company spokesman, total production from the units have more than doubled that from older rigs. This article describes how the draglines are used and provides details on the New Wales operation. The principle product at New Wales is phosphoric acid, produced by reacting ground phosphate rock with sulfuric acid in large concrete attack tanks. For each ton of phosphoric acid produced, New Wales must dispose of about 4.5 t (5 st) of waste gypsum. New Wales stores the gypsum on-site, and uses durable Northwest draglines to help handle the material. Two Units Maintain the Gypsum Stack After the gypsum is separated from the phosphoric acid through 23-m-diam (75-ft-diam) vacuum filters, it is mixed with water from a 121-hm2 (300-acre) recirculating cooling pond and, in slurry form, is pumped to the top of a 121-hm2 (300-acre) gypsum stack located adjacent to the cooling pond. The slurry contains mostly gypsum (CaSO4), with small traces of silica and other elements. The water at this point is corrosive, containing from 1-2% phosphoric acid. Its pH usually ranges from 1.5-2.0. Water drains from the gypsum stack into the cooling pond. Only about 15% of the pond's water, however, comes from the gypsum stack; the balance is from various sources throughout the complex and is held in the pond to cool before being returned for reuse in the plant. About 97% of New Wales' water needs come from this recycling program. The gypsum remains on the stack, inert, ready for future processing if it becomes economically feasible. Throughout the handling process, Northwest draglines work around the stacks' rim, continually directing the waste flow and digging out dried solids to heighten the perimeter dike to provide more storage volume. When wet, gypsum is extremely soft. When dry, it compacts well and provides footing with enough bearing capacity to support the machines. Processing at New Wales started in 1975 and the gypsum storage area has already been built up 12 m (40 ft) above grade. A total of 14.8 km3 (12,000 acre-ft) of solids are now stored. The draglines dredge material from near the perimeter dikes and place it to build parallel berms. This

Jan 8, 1982

By Tim Neil, O&apos

The coming years should see moderate growth in the US coal industry. That growth may come at the expense of the oil and natural gas industries. Conoco pegs coal growth at 2% a year, until the year 2000. During that same period, Conoco projects only 0.5% annual oil growth and "a flat or negative trendline" for natural gas. This is compounded by the fact that coal has a delivered cost per Btu that is only half as much as it is for natural gas and only a third as much as it is for oil. So said Ralph Bailey to many of the 2600 attending the opening session of the American Mining Congress Coal Convention, May 12-15, in Pittsburgh, PA. Bailey is chairman of the AMC. He is also chairman of Conoco. While coal's projected growth is not spectacular, "it is in fact almost an assured growth," Bailey said. Weak oil and gas prices will likely prevent faster growth for US coal. Most of coal's increased demand will come from the electric utility industry and expanded steam coal exports. Conoco's study projects that domestic coal demand will be strengthened in the 1990s. By then, the present surge of nuclear power plant constuction will be over. And there will be a lack of acceptably priced, large-scale generation alternatives for utilities. "It is not likely that any electric utility is going to be ordering new nuclear reactors," Bailey said. "And as oil and gas supplies become scarcer and more costly, it is only logical that coal is going to fill the gap." At the same time, Bailey believes the US coal industry must find ways to lower its costs. He said cost excesses can be found in "regulatory overkill, labor, and simply bad habits" hidden by years of high inflation. "Those costs have now been laid bare, because we are going through a pe¬riod of disinflation. We have to put our house in order, particularly if we are going to compete in world markets." Bailey also touched on coal research. "The industry certainly accepts the fact that we must find a way to burn coal as cleanly as possible. A lot of work in that regard is going on. I expect there will be some significant break-throughs." Bailey said the coal industry is being squeezed this year. Last year, coal customers accumulated inventories in anticipation of a major coal strike that never materialized. Now, many utility customers are working down these inventories. So they are not taking deliveries on their coal contracts. But coal use is up in 1985, compared with 1984, Bailey said. So increased coal use, along with supply drawdown, should strengthen the coal market before the year is out, he said. After Bailey's presentation, some 100 speakers addressed policy and technical topics at 15 sessions during the four-day meeting. It was the first time since 1977 that the AMC Coal Convention has been held in Pittsburgh. And this year's attendance was up 40% from the last AMC Coal Convention held two years ago in St. Louis, MO. This year's registrants included 228 companies, 225 manufacturers, and 106 associated members. The only negative was the David Lawrence Convention Center. It was less than ideal. By turns, meeting rooms were too small, too cramped, or too far from one another. The session on longwall mining was so crowded that the doors were propped open so conference delegates could peer in. A concurrent manufacturers' forum session needed 50 more chairs to accommodate those wanting to attend. However, on to summaries of some of the presentations. Coal transportation and export Since Congress approved the 1980 Staggers Rail Act, railroad rates for hauling coal have not been excessive. In fact, rail rates for coal have increased less than 0.5% a year, in real terms, since 1980. Moreover, the market oriented principles written into Staggers are contributing to the improved financial and operational health of the nation's railroads. But no railroad is earning excessive profits. That is the gist of a coal transportation study being completed by the US Department of Energy. William Vaughan is DOE's assistant secretary for fossil energy. He affirmed the thrust of the upcoming report. Vaughan did allow that Interstate Commerce Commission (ICC) regulations on rate reasonableness could permit the railroads to exploit their monopoly power on captive shippers. Luncheon comments later made by Don Hodel confirmed Vaughan's comments on railroad rate justification. Hodel is Secretary of the

Jan 7, 1985

By Youning Li, William J. Drury, Christopher H. Gammons

A demonstration scale, subsurface flow anaerobic wetland was built to treat zinc and other metals in surface drainage near the historic mining center of Butte, MT. Based on three years of continuous monitoring (1996-1998), copper and cadmium were effectively removed year-round, but attenuation of dissolved zinc was dependent on hydraulic residence time (HRT) and bacterial sulfate reduction (BSR) rates. BSR rates decreased in winter months, as did HRT due to the development of thick frost zones in the substrates. An additional problem was the inability of the wetland substrate to completely filter out fine-grained particles of ZnS forming in the anaerobic cells.

Jan 1, 2000

By William C. Cooley

Modern tunnel boring machines are subject to excessive cutter wear and bearing failures when used in hard and abrasive rock. In very hard rock, the high cost of cutter and bearing replacement, combined with slower excavation progress, make it more economical to drive tunnels by conventional drill and blast methods. The use of high pressure water jets to break rock provides a promising alternative. Experimental data indicate that the specific energy (the energy expended per unit volume of rock broken) decreases as the water jet pressure increases. Continuous jets are generally limited to pressures below 100,000 psi, whereas pulsed jets from a water cannon can attain much higher pressures. Therefore, the Federal Railroad Administration of the U. S. Department of Transportation has sponsored the design (Ref. 1 & 2) and the fabrication and testing (Ref. 3 & 4) of a water cannon to determine its effectiveness in rock disintegration at very high pressures. This paper reports the results of laboratory tests with pulsed jets against large rock samples at pressures of 125,000 to 650,000 psi and field tests against dolomitic limestone and granitic gneiss at pressures near 450,000 psi. Although initial tests were made with a small nozzle, operating at off-design conditions (Ref. 4), this paper only covers results with the full-size nozzle, including 55 laboratory test shots and 67 field test shots.

Jan 1, 1974

By Michael A. Linkous, Mark J. Zdunczyk

Silica in the form of sand and sandstone is one of the most common, and at the same time, unique industrial minerals. Found in every rock type of every geologic age and virtually everywhere in the world, silica is used in products that touch just about every aspect of daily life. Imagine a world in the 1990s without computer chips, fiber optics, or glass, and you have just begun to understand how important silica is to the quality of life we enjoy. The elements silicon (Si) and oxygen (0) comprise roughly 60% of the earth's lithosphere to a depth of about 16 km. The crystal structure of silicon dioxide consists of one atom of silicon bonded to four surrounding atoms of oxygen to form a three-dimensional network of SiO, tetrahedra. This network makes up the mineral quartz (Murphy and Henderson, 1983), the most common detrital mineral in most sandstones. Quartz is also a major constituent of many igneous and metamorphic rocks and is widespread as a siliceous cementing agent in various rock types. Although quartz is common, sandstones, quartzites, and pegmatites and the unconsolidated sediments derived from them that have a silica content high enough and pure enough to meet today's market demands for quality and consistency are not common. USES AND SPECIFICATIONS Silica sand that is mined and processed for industrial uses must conform to the chemical and physical specifications set by customers. In the United States almost half of the silica sand produced is used in the manufacture of glass. Other important products include foundry sand, ground silica, blasting sand, and fracturing sand. Glass Sand Silica is the principal glass-forming oxide in a glass batch. Glass manufacturers develop model specifications for each source of silica sand used. These specifications broadly define the limits and ranges for chemical and physical properties of the sand and are used by the manufacturer in calculating the desired batch mix or formula. Some specifications may be critical to a glassmaker and require very stringent limits on the quantity of impurities in the sand. For example, the total iron oxide content of a batch is extremely crucial when making white or flint glasses (Mills, 1983). Iron is present in almost every raw material used in a glass batch and must be carefully controlled in order to obtain a consistent color in the finished product. It is difficult, however, for a raw material supplier to tightly control the chemistry of a naturally occurring material such as silica sand. To a great extent the commercial quality of a sand is determined by its geologic history. Realizing this, glass producers tailor their model specifications to each source of approved material. In general, a glass company is concerned most about the consistency of raw materials on a day-to-day basis. Soda-lime-silica glass was the earliest type of manmade glass (Baker-Can, 1967) and still accounts for most of the glass manufactured for commercial use today (Mills, 1983). It is relatively easy to melt and shape and is less expensive per ton to produce than most other types of glass (Baker-Can, 1967). Soda-lime-silica glass is used in fabricating containers, flat glass products, incandescent and fluorescent lamps, glass fiber, and many other products. Heavy minerals such as ilmenite, leucoxene, kyanite, and zircon are impurities on which strict limits are placed for a glass batch. Because of their refractory nature they either do not melt or only partially melt, which results in stones or feathers in finished glass. Aluminosilicates such as kyanite also contribute unwanted alumina to the batch as they partially melt. Limits are especially rigid for refractory mineral grains coarser than 0.60 to 0.425 mm (30 to 40 mesh). [Tables 1 and 2] present typical specifications for silica sand used in flat glass and container glass products. The percentages shown represent an average of many companies7 specifications.

Jan 1, 1994

By Poltak Sinaga

PT Kaltim Prima Coal's 13.1 km overland conveyor was commissioned in 1991. It is of conventional 3 roller 350 troughed belt type. Cost and performance optimisation during initial design ended up with 5.4m/s belt speed, 1,000mm belt width to convey 1,350tph, and 7mtpa of coal. Despite high initial figure, the belt speed was lifted to 6.5 mps in 1996 to accommodate mine throughput increase. In 2002, new low loss ST2100 1,100mm wide belt replaced the old ST2250 due for change-out. An upgrade project was initiated at the end of 2003 to further increase the belt speed to 8.5 mps, hence to increase the OLC capacity to 30mtpa. Performance data, experience of site personnel, site observation and tests, benchmarking, and information from equipment manufacturers were major inputs to the design review. The project fast track was another challenge in addition to executing modifications on a production lifeline. The project was completed within fifteen months and the OLC was successfully commissioned at 8.5 mps belt speed in February 2005. The OLC has been to date conveying 4200tph satisfactorily.

Jan 1, 2008

"INTRODUCTION The characterization of groundwater hydrogeology is a common component in feasibility studies, geotechnical investigations and regulatory permitting for mining operations. The lithology at a location of interest may include several discrete water-bearing units; and the means of isolating each for testing can be accomplished through the use of inflatable packers. Consideration for testing during drilling program planning and communication between all stakeholders is essential to ensure that the Mine, Drilling Contractor and Hydrogeological Testing Specialist (Specialist) are ready to perform packer testing when the call is made to mobilize. Often, the notice to mobilize can be delayed and then occur with little warning due to the issues that can occur during drilling of very deep boreholes, as well as other factors. Hydrogeological investigation reports and journal articles generally discuss testing methods and results, with limited information available describing the planning and coordination of the field testing program, as evidenced by the lack of references cited below. The source of inspiration for the subject matter of this paper is grounded in the author’s past shortsightedness; with the hope that others not share similar misfortunes but experience success through thorough preparation for their future hydrogeological testing programs. The sections below focus on the planning stages of a field investigation using inflatable packers, including considerations for site specific conditions, designation of stakeholder responsibilities, and communication of testing expectations. Following these sections is a presentation of two examples of successful field programs and lessons learned in addressing problems encountered along the way. PRELIMINARY PROGRAM PLANNING & CONSIDERATIONS From the onset of planning for drilling programs, the Specialist should be in communication with the Mine to review plans and identify fatal flaws which could impede collection of hydrogeological data. Preliminary scope decisions can significantly affect the budget and duration of hydrogeological field programs and may dictate the means by which the field data is collected. The issues that need to be considered include the following factors. Testing Objectives The setup of the packer tool is dependent on the testing objectives. Is the goal to estimate bulk aquifer hydraulic conductivity or to identify discrete discontinuity hydraulic characteristics? Are groundwater samples needed? The answers to these questions affect selection of test interval length and what instrumentation might need to piggyback on the packer tool. Identifying the testing goals initially will provide adequate time to prepare packer equipment for mobilization. Borehole Size While inflatable packers come in many shapes and sizes, some sizes are more readily available and easier to procure on short notice. Packers for NQ and HQ size boreholes have been historically easy to procure and are commonly used in exploration drilling. Packer equipment is available for smaller holes, but it becomes more difficult to fit instrumentation down-hole as the borehole size decreases. This is particularly a consideration if collection of groundwater samples is required. In addition, risks of losing the hole or equipment downhole are greater for smaller boreholes. Larger boreholes require larger packers and clearly require more effort and heavier capacity machinery to manually manipulate due to the increased size."

Jan 1, 2017

By Kanaan Hanna, Mir Heydari, Dipack Sengupta, Gordon B. French

This article concludes a two-part series on the safety, technology, and economic impact of eliminating safety fuse from metal and nonmetal mines. Discussed are the consequences of fuse abolishment, the technical feasibility of changing to an alternative system, and an economic analysis of initiation systems. Last month, part one (ME, pages 31-35) described current use of initiation systems, incidence of accidents, and consumption values for safety fuse and other initiation systems. Consequences of Fuse Abolishment Cap and Fuse Manufacturers Two major safety fuse manufacturers, Ensign Bickford and Apache Powder Co., share the US fuse market. Marketing of Ensign Bickford safety fuse is done by Dupont. Dupont manufactures electric caps as a main product and recently introduced a new nonelectric initiation system (Detaline). Therefore, Dupont would be only slightly affected by the elimination of safety fuse from metal and nonmetal mining. Ensign Bickford, though a larger manufacturer of fuse, does not appear to emphasize the safety fuse market. In fact, safety fuse sales represent only about 10% of Ensign Bickford's total sales volume. Ensign Bickford is strongly pushing its Nonel product. It appears, therefore, that the elimination of safety fuse would have a limited effect on Ensign Bickford, and could ultimately be to the company's advantage. Apache Powder Co., however, would be seriously affected if safety fuse was eliminated. Safety fuse, although not its only product, constitutes a major source of revenue for the company. It currently does not manufacture a substitute product. Apache Powder Co.'s manager agrees that prohibiting the use of safety fuse would result in a greater market share of initiators for Ensign Bickford. Hercules could also benefit from the prohibition of safety fuse. Metal and Nonmetal Mining Industry According to an explosive company contact, elimination of safety fuse by a mandatory regulation would force some of the small, marginal mines out of business. Another powder company representative believes that eliminating safety fuse will result in uneasy situations for small operators not familiar with other techniques. These operators try to minimize the costs and traditionally like safety fuse. He believes that insufficient proof exists to substantiate the overall safety increase if the fuse is eliminated. Fuse manufacturers and distributors disagree, then, about the impact of safety fuse elimination. However, they tend to agree on some important points: • Safety fuse can be a safe method if applied properly. • Electric blasting can be dangerous due to stray currents, and may have higher misfire rates than safety fuse. • It is very difficult to compare the rate of misfires and partial round failures for different systems. This is due simply to the nonavailability of such data. In many cases, the misfires are not even reported to the shift boss, as required by regulations. • Safety fuse has high acceptance in certain applications, such as a face where Nonel or detonating cord are used, or in open-pit blasting. • The safety fuse industry appears to be phasing out on its own. It is expected that the fate of the safety fuse market will be similar to that of black powder. An investigation by Nitro Noble of Sweden "clearly states that the diminishing use of safety fuse has considerably reduced the accidents in Swedish mines." Mine Data Acquisition and Analysis As a part of the study effort, visits were arranged to 24 metal and nonmetal mines. In most cases, underground visits were accomplished. At least one drilling and loading operation was witnessed. The mines were grouped into four mining areas: Wyoming, Montana, Idaho; western Colorado and eastern Utah; Missouri; and southern Arizona. Of all mines visted, the safety fuse system was used in 11 mines, electrical system in seven, Nonel in five, and the Hercudet system in one surface mine. At each mine, the manager, foreman, and blasting crew were interviewed for information and opinions. Besides informal discussions with mine officials, a questionnaire was also filled out for each mine. Due to the extensive length of the information gathered, these data are not presented here.

Jan 2, 1984

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 K. N. (Mani) Subramanian

A 2.5 meter diameter column has been successfully used in a 100 tph flotation plant at the Harbour Lights Mine in Leonora, Western Australia, to produce a final gold bearing sulfide concentrate from the ore in a single stage. This pioneering application of column flotation cells to rougher stage was pilot tested using a 11 cm column, which demonstrated column's capability in rougher, scavenger and cleaner flotation stages. A hybrid circuit involving columns and mechanically agitated flotation cell s was adopted for the commercial installation. This paper describes pilot plant results, design of the plant flotation circuit, and early results of commercial operation.

Jan 1, 1988

By Houston Kempton, David Atkins

Mining in semi-arid climates can produce environmental impacts that will not begin for hundreds of years, but once started, may continue for thousands of years. Pit lakes may eventually exceed toxicity thresholds as metals are evaporatively concentrated, and slow unsaturated flow through acid-generating waste can eventually load several kg-SO4/m2-yr to underlying water tables. U.S. regulations are poorly equipped to respond to delayed and long-term environmental impacts, delaying permits as operators and regulators grapple with uncertainty. Improved uncertainty analysis, additional long-term mitigation options, and explicit regulatory guidance offer solutions to this dilemma.

Jan 1, 2000

By E. Topuz

This paper discusses factors affecting the productivity of continuous coal mining operations. It analyzes design and operational relationships in continuous mining systems, and investigates how their productivity can be improved by selecting the number of headings, the dimensions of pillars, and the depth of cuts as well as the miner loading rate and tramming speed, the shuttle car payload and hauling speed, and the roof bolting cycle time. A computer simulator has been found very efficient in analyzing effects of section layouts and equipment operating characteristics on the productivity of continuous coal mining systems.

Jan 1, 1987

By J. C. Zelanko

The U. S. Bureau of Mines conducted a multi-faceted geomechanics research project at a bump-prone longwall coal mine in eastern Kentucky. This mine presented a unique opportunity to study coal mine bumps in that the problem appeared to be confined to areas beneath a sandstone channel of limited areal extent. The Bureau's research plan sought to exploit the uniqueness of the site by monitoring strata behavior and longwall support reactions as the longwall face approached and passed beneath a sandstone channel. The study incorporated static pillar stress and strata deformation measurements, shield support leg pressure measurements, and microseismic monitoring as well as geologic mapping and the collection of observational data. Data collection was underway when a major coal bump occurred on the longwall face at the mine. Pillar behavior (load and deformation), shield loading, and microseismic activity were monitored prior to, during, and after the bump. Observations in the tailgate indicated that these pillars were failing prior to and after the face bump. Shield load data which were evaluated in an effort to identify trends which could be used to forecast coal bumps appear to provide a measure of the effectiveness of destressing operations conducted on the face (e.g. shot firing). Analyses of microseismic data revealed anomalous values associated with microseismic "energy" prior to the face bump. In addition, microseismic source location data and underground observations provided some insight as to the sequence of pillar and face bumps.

Jan 1, 1991