Search Documents

By J. E. Lowe

The unique application of a large walking dragline in the mountains of southern West Virginia was developed and implemented by Hobet Mining, Inc. Hobet is an independent operating subsidiary of Ashland Coal and is headquartered at the No. 21 Mine in Boone County, West Virginia, near Danville. Hobet also operates the 07 Mine located in Logan County, West Virginia, near Holden. Both mines are similar in equipment and manpower used; both produce over 2,000,000 tons of clean coal annually. Each site encompasses large, contiguous properties with access to rail service. The larger of the two is the Boone County property; it totals nearly 40,000 acres and has ample reserves. In 1977, Hobet was in the process of constructing a preparation plant (Beth Station) at its 21 Mine site with a capacity for two million tons. One of the first orders of business was to design a mine plan that would provide production for the capacity of the plant. Coal production would come from a more than adequate reserve base using the most economical mining methods available. Hobet looked at different deep and surface mining methods to use in order to develop the property; ultimately, it was determined that the mountaintop removal method with the use of a large dragline was the most economical way to develop reserve. Prior to this time surface mining in mountainous Southern West Virginia was generally done by contour mining and/or augering techniques.

Jan 1, 1993

By J. Hansen

"ABSTRACTThe paper addresses the application of automated monitoring, control, and navigation to improve dragline performance. SummaryImproving dragline performance in the Canadian coal mines is critical to the continued success of the industry. Draglines represent a large capital investment and coal prices are low by historic standards. This paper argues that the introduction of monitoring, control, and navigation on draglines offers an opportunity to significantly reduce a dragline’s operating cost per cubic metre moved. To place the importance of this in perspective, a North Dakota mine calculates that every 1% increase in dragline productivity means a savings to the mine of US$340,000 per year. MonitorsAutomated dragline monitoring is a well established technology with commercial products available since the early 1980s. The three main reasons for placing monitors on draglines are (Walker, 1993):1. productivity increases: reduce variations between different operators’ performance across different shifts;2. quality increases: increase the percentage of ore and waste loads that go to the correct destination; and3. special projects (engineering projects): justify installing static field exciters and regulator upgrades; implement power management; aid operator training; study high performance buckets, rigging changes, and various excavation sequences.Mines as diverse as Kennecott’s Cordero- Rojo Complex in the United States and Natal Coal Corp.’s Optimum Mine in South Africa report dragline productivity increases of 10% to 20% in the region attributed to the implementation of dragline monitoring."

Jan 1, 2000

By Lumley G. I, Hayes H

Non-intrusive methods for the reliable determination of dragline bucket and rigging performance have been achieved using physical modelling. Modelling offers a logical first step towards developing mathematical simulation models. The process of physical modelling has been applied successfully to predict dragline bucket performance and capacity as well as to demonstrate the effect of varying dump rope length on performance. ACIRL's Surface Miming Group has used physical modelling to carry out dragline bucket sizing for a new high productivity bucket and compared performance with Throng Coal's existing dragline bucket. The predicted bucket performance has since been confirmed in the field using dragline monitoring techniques.

Jan 1, 1992

By R. Adsero

"A high altitude review of the state of the mining industry provided by a study of multifactor productivity shows a continuation of lower output year on year for the capital and labor inputs applied. The story is sadly similar for both U.S. mining and the Australian mining sector. In fact, according to PwC analysts, the world’s mining equipment productivity has declined 20 percent during the past seven years (Lumley, 2014). Although the reasons for the continuing decline in mining productivity are varied, the need for improvement is clear.The world’s mining industry fleet of more than 400 large draglines moves billions of tons of overburden and ore (phosphate, limestone, etc.) annually. This discussion will review a few of the tools available for improved productivity in dragline operations.Benchmarking equipment performance exposes the possibilitiesIn the September 2013 Mining Engineering cover story Graham Lumley and R. Adsero suggested that analyzing best practice equipment performance from an industrywide database for specific equipment performance improvement goals would be beneficial (Adsero, 2013). Benchmarking equipment performance by normalizing differences and then comparing specific measures of performance will provide a road map to improvement for those following the leaders. For those already performing at best practice levels, a benchmark confirms and bolsters what has already been achieved. As described in the SME February 2014 paper by this author, best practice is the average of the top 10 percent in annual output. Filling performance gaps identified by a comparison to best practice by investigating the details of the why and taking action to change, makes all the difference. This is true for all major mining equipment. Given the large gap between average performance and best practice performance most mining operations can benefit. Best practice performance provides a view of what is possible to the 90 percent majority of mining operations that are performing below the top 10 percent.For dragline mining operations, identifying specific characteristics and practices of leading dragline performance will provide a reference for comparison."

Nov 1, 2016

By M. L. Bricker

The Jim Bridger Mine is operated by Bridger Coal Company and is located in Sweetwater County, 35 miles (56 km) northeast of Rock Springs, Wyoming (USA). The general location of the mine site is shown on Figure 1. Bridger Coal is a joint venture of NERCO Coal Corp, the operator, and Idaho Energy Resources Company. The permit boundary encompasses in excess of 20,000 acres (81 km2) and is nestled against the western side of the Continental Divide. Production started on July 3, 1974, and the mine has produced approximately 90 million tons (82 million t) while moving approximately 450 million cubic yards (344 million m3) of virgin earth. Annual production averages 5 to 7 million tons (4.5 to 6.4 million t) of run-of-mine coal. Coal is consumed on site by the Jim Bridger Power Plant, a 2,000-megawatt generating station, and the electricity is transmitted to the Pacific Northwest power grid (Oregon, Idaho, Northern California, etc.).

Jan 1, 1991

By Mark L. Bricker

The Jim Bridger Coal Mine, operated by Bridger Coal Co., is located in Sweetwater County, WY about 56 km (35 miles) northeast of Rock Springs. Bridger Coal is a joint ven¬ture between Nerco Coal Corp, the operator, and Idaho Energy Resources Co. The permit boundary encompasses more than 81 km'- (20,000 acres) on the western side of the Continental Divide. Since the mine began opera¬tions in 1974, it has produced about 82 Mt (90 million st) of coal while moving about 344 hm3 (450 million cu yd) of virgin earth. Annual production averages 4.5 Mt to 6.4 Mt (5 million to 7 million st) of run-of-mine coal. Coal is consumed on-site by the Jim Bridger Power Plant, a 2000-MW generating station. Electricity is transmitted to the Pacific Northwest power grid that includes Oregon, Idaho and northern California. Geology The mine is located on the northeast flank of the Rock Springs uplift. This is a broad, asymmetrical anticlinal feature about 97 km (60 miles) long and 56 km (35 miles) wide with a north-trending axis. This uplift separates the Green River Basin to the west and the Great Divide and Washakie Basins to the east. Precambrian rocks on the apex of the uplift are estimated to be 5200 m (17,000 ft) above the Precambrian rocks in the Green River and Washakie Basins. Normal faults with generally less than 30-m (100-ft) vertical displacement cut through the uplift. The dip of strata on the flanks is generally between 3° and 15°.

Jan 1, 1991

By Fry P. R

Dragline operations have played a major and successful role in coal mining around the world for more than 30 years. Because of this long history, many of the operating draglines are reaching an age where maintenance and downtime costs are prohibitive, and decisions need to be made to either replace or refurbish them.In the current economic climate, refurbishment is a popular choice and this usually involves major structural repairs above and below the roller circle, together with replacement of the roller circle components. Often, the dragline tub is also replaced by a completely new one.

Jan 1, 1992

horizontal-type classifier prior to charging into a blastfurnace.

Apr 1, 1995

By J. R. Dillon

Today more than ever, there is an increased demand for higher plant production capacities and efficiencies to offset the increasing costs for labor and materials. Plants involved in processing large volumes of bulk materials are particularly interested in more efficient material handling systems to (1) reduce labor and maintenance costs, (2) improve blending of non-uniform raw material feed to processing facilities, (3) improve blending of finished bulk materials from storage. DragScraper systems are being used effectively for handling a variety of bulk materials in both indoor and outdoor storage. Materials being handled include ores, chemicals, coke, clay, and stone, to name a few. Handling capacities these machines can provide vary from a few tons to over 1500 tons per hour. The basic components of a DragScraper machine consist of a bottomless Crescent scraper, a two or three-drum DragScraper hoist assembly including gas, diesel, or electric power unit, operating cables, guide blocks, and either fixed or mobile head and tail structures. They are presently available in sizes through 15 cubic yards, for operating spans up to 1000 feet.

Jan 1, 1969

By John K. Berry

The handling and disposal of mine water is a much larger problem than is apparent at first glance. Many more tons of water are removed from underground coal mines in the United States each year than tons of coal. In the old anthracite region of Pennsylvania the average was around 36 tons of water for each ton of coal produced, while bituminous mines average about 5 or 6 tons. Water encountered in the mines may come from several different sources. In mines with light cover and without a firm solid roof, rain may seep directly into the workings. This is also true of deeper mines where pillar falls have broken the roof to the surface. The top under creek beds is generally faulty and broken and water comes through the roof at this point. Deeper mines are frequently overlain by water-bearing strata and pillar breaks and faulty top can admit water, while places running to the dip often accumulate water which comes up through the bottom. In all cases, except where passing under a year-round stream, the amount of water made is usually pretty closely connected with the weather-more water during the rainy season, less in the dry, although the deeper a mine is, the longer it is before changes in rainfall are felt. Another source of water, not connected with seasonal changes, is old water, accumulated over a period of time in abandoned workings of the mine, or from flooded adjacent mines. Here the water filters through the coal, the parting, or comes up through cracks in the bottom. Similarly, core holes, drilled to prospect the property, can be a source of unexpected water and modern safety requirements for dust-allaying water at the working faces can turn a pleasant working area into a soggy mess over the weekend if the system is not properly maintained and operated. Why water must be disposed is obvious. If allowed to accumulate, sooner or later the mine will fill up, or at least it will become "roofed" in low places, blocking ventilation and traffic. But it must also be controlled long before it reaches this stage. Water standing in the working faces is unpleasant for the men who have to work there and also cuts down on the amount of work they can do, as they must watch where they step all the time. It is especially unpleasant in low coal.

Jan 1, 1973

By Alan J. Zeni

Drainage of water from abandoned underground mines has become important in recent years because of safety concerns when mining near abandoned works or reentering abandoned mines for further development. Seepage from inundated mines causes environmental damage and may threaten homes and communities. Where topography permits, horizontal drilling can provide a quick and cost effective method for solving trapped water problems. The mechanics of the horizontal drilling operation as applied to water drainage are discussed in this paper.

Jan 1, 1990

By K. A. Lapakko, D. A. Antonson

Fourteen samples of pyrite-bearing Archean greenstone rock (d < 6.35 mm, 0.04% < St < 1.22%) were characterized (particle size, chemistry, mineralogy) and subjected to laboratory dissolution testing. The only sulfide and carbonate minerals identified were pyrite and siderite, respectively. Quartz, chlorite and sericite typically comprised 90 to 98 percent of the mineral content. For the first 60 weeks, seven samples with sulfur contents less than or equal to 0.16% produced drainage pH values exceeding 6.0. Over this period, six of the seven samples with sulfur contents greater than or equal to 0.20% produced drainage pH below 6.0, with minimum values ranging from 3.2 to 4.7. The seventh sample (0.72% S) had a siderite content of 18%. Small amounts of magnesium and, to a lesser degree, calcium carbonates present in the siderite apparently dissolved to neutralize acid and maintain drainage pH above 6.0. Sulfate release rates generally increased as sulfur content increased, and the rates of pyrite oxidation estimated for individual samples were roughly half to five times that reported in the literature for the abiotic oxidation of pyrite by oxygen. Observed neutralization potentials ranged from 0.2 to 2.0 g CaCO3/g rock.

Jan 1, 2002

By Ben Sosewitz

The subject of rapid excavation tunneling is one that is extremely important to the people in the Metropolitan area of Chicago. My personal observation is that it is also extremely important to the urban communities around the U.S., to many local and state governments, and to the public officials who are deeply concerned about state affairs and taxes. The Metropolitan Chicago area is in fact, (as are 40 other major urban areas in the U.S.) confronted at the present time with a very serious combined sewer overflow, drainage and pollution problem which accounts for an estimated 40% of the pollutional load on its waterway system. In response to this the District has to date spent some seven millions of dollars in an attempt to find the most economical solution available for the elimination of this problem. This study included extensive investigations of the geological strata, the quantity and quality of storm runoff to be dealt with, and the various methods of storage and treatment available. It has considered solving the overflow problem by a concept involving a series of tunnels, rock tunnels, shafts and storage areas which will collect, retain and subsequently treat that portion of the combined sewer overflow which can be handled in the most cost-effective and economical way, consistent with following the federal and state standards - with which we at the present time agree in principle.

Jan 1, 1997

By J Chen

Research conducted into backfill drainage at Mount Isa Mines since 1992 is described. Piping in draining backfilled stopes has been the primary cause of bulkhead failures and emphasis is placed on research into the piping mechanism. Laboratory and in situ tests aimed at understanding the piping mechanism have been conducted and the results are presented. A case history of piping in a draining bench stope fill mass is described and a technique for reducing the potential for bulkhead failures in bench stopes is presented. Hydraulic fill is produced by standard cycloning of tailings and the overflow (reject material) is sent to thickeners prior to placement in the tailings dams. Research into the partial introduction of thickener underflow into the backfill system and its influence on backfill drainage is also described.

Jan 1, 1998

By Chend J

Research conducted into backfill drainage at Mount Isa Mines since 1992 is described. Piping in draining backfilled scopes has been the primary cause of bulkhead failures and emphasis is placed on research into the piping mechanism. Laboratory and in situ tests aimed at understanding the piping mechanism have been conducted and the results are presented. A case history of piping in a draining bench scope fill mass is described and a technique for reducing the potential for bulkhead failures in hench stopes is presented. Hydraulic fill is produced by standard cycloning of tailings and the overflow (reject material) is sent to thickeners prior to placement in the tailings dams. Research into the partial introduction of thickener underflow into the backfill system and its influence on backfill drainage is also descrihed.

Jan 1, 1998

By David Hake, David Salisbury

The Drainage Services Department (DSD) of the Hong Kong SAR Government commissioned the design and construction of the West Kowloon Drainage Improvement, Stage 2, Phase 2, Kai Tak Transfer Scheme (KTTS) project in 2000 to relieve potential flooding in Mong Kok caused by the insufficient capacity of the existing storm water drainage system. The KTTS involves construction of a 1.5km,4.4m drainage tunnel and a 450m long box culvert, running from Waterloo Road near Hereford Road to the existing Kai Tak Nullah in San Po Kong. This paper describes the design and construction of; the bored tunnel through both hard rock and soft ground using a slurry Tunnel Boring Machine (TBM), six associated access shafts, a connection structure at Waterloo Road and the box culvert connecting the bored tunnel to the outfall at Kai Tak nullah. Details will be provided on the contractor’s alternative designs adopted during the contract including the use of fibre reinforced shotcrete as one-pass temporary and permanent support for three of the shafts and modifications to the Engineer’s design for the box culvert structure.

Jan 1, 2005

The clay slime generatea in many sand washing operations is usually very difficult to de-water. Treatment of these slimes is often limited by economic considerations and the properties of the solids to a gravity-driven process. The moisture characteristics of kaolinitic slimes from two different sand washing operations were measured.From these curves, equilibrium moisture contents for sedimentation and for drainage were calculated using the methods of soil physics. The validity of these calculations were confirmed by column experiments.The results show that the increased de-watering to be gained by drainage, as compared with sedimentation, is significant. Furthermore, observed rates of outflow indicate that water can be removed considerably morerapidly when drainage is possible.The practical application of these results to the dewatering of clay slimes is discussed.

Jan 1, 1978

By Osvaldo A. Bascur

One of the most vigorous of the continuous improvement methodologies is Six Sigma. While usually associated with improving manufacturing and product quality, leading manufacturers are using it to improve their extended supply chain and logistics capabilities. At the same time they are improving reliability, some companies have cut hundreds of millions of dollars of fat out of their supply chain. Mine to Mill optimization is a transformation of culture from processing tons to processing a quality feed size distribution which reduces the overall operational costs and add the highest value to the mine. This is not a constant endeavor. As such, a dynamic performance monitoring and diagnosis is necessary. We will review a systemic way to performance improvements and avoiding metal losses from the blast to the metals. We show the requirements of using raw data to analysis the data to define operational maps which provide assistance to run the mine and mill. A case study is provided with the mine and mill data was integrated combining process control and quality information resulting in reduction of water and energy consumption while improving the overall value of the mine. The results of reengineering the current system with this SIX SIGMA Strategy had the following results: an increase of ore milling: 4.6% decrease of mil power: 3.9%, decrease of fresh water consumption: 6.8%, with a total of net profits: US$ 31.8 million, the PI System infrastructure contribution: US$ 7.95 million. These estimates were for the period 2009/04/04 to 2009/12/31.

Sep 1, 2012

By Homer S. Frankhouser

Materials may be dredged, processed, stored and loaded for shipment at a single site in water depths ranging from 250 to 1200 ft. Solution mining may also be accomplished in deep sea situations. And, open air subsea mines with direct surface access may be developed and worked under the ocean floor. These concepts for deep sea mining are the results of extensive testing of individual components of the proposed systems by Dravo Ocean Structures, Inc., a subsidiary of Dravo Corp. A basic structure in these systems is the articulated platform. The platform consists of a gravity- type base and a buoyant cylindrical column which is constructed at an onshore location, towed to the offshore site and installed in a matter of days without use of heavy equipment. The base is also buoyant for towing purposes. This allows for gradual flooding to the point of negative buoyancy for positioning and anchoring to the ocean floor.

Jan 1, 1971

By William Bogan, Mark Vaivoda, Richard Daniele

Many factors must be considered when performing engineering and construction work for a major minerals project. Dravo&apos;s Afton copper smelter in British Columbia illustrates some of the E&C factors considered when setting up this new operation. In March 1978, Afton Mines Ltd., a Tech Corp. subsidiary, began blister copper production at the world&apos;s first integrated copper ore mining, milling, and smelting operation to use Top Blow Rotary Converter (TBRC) process smelting technology. This key TBRC smelting element is licensed by INCO Ltd. to Dravo Corp. The TBRC process uses a single vessel of modular design. It rotates for mixing and provides complete processing capability, from concentrate through blister copper. The Afton facility is about 16 km west of Kamloops, a town in south-central British Columbia. To make its operation as economic as possible, Afton officials considered several options for the copper smelter, the first in modern times in the province. Inability to extract precious metals-primarily gold-from the concentrates ruled out hydro-metallurgical processes. The final choice was between a conventional electric furnace/ Peirce-Smith converter combination and the TBRC process. The TBRC process was chosen for its versatility in processing the various Afton concentrates and grades and its 40% lower capital cost compared to the electric furnace converter system. The TBRC smelter -including concentrate slurry receiving, drying, storage, smelting, off-gas cleaning, and copper casting-had an installed cost of about $25 million. In December 1974, a pilot program was conducted by Teck, Dravo, and INCO at INCO&apos;s Port Colborne, Ontario, research facility. The pilot program demonstrated the TBRC&apos;s ability to smelt, convert, and clean copper slags. After the successful pilot effort, Dravo performed additional research to find an effective fixation system for high grade, intermittent SO2 gases. Once the go-ahead was given, design and procurement for the Afton copper smelter was provided by the Denver Division, Dravo Engineers and Constructors. Commonwealth Construction, Vancouver, constructed all Afton facilities. Afton&apos;s single furnace smelter is designed to produce 25-kt/a blister copper in 363-408 kg cake form. The product is sold to England for electrolytic refining. The TBRC process is only one of several innovations proposed by Dravo and chosen by Afton to insure the most modern smelter in North America and meet all British Columbia&apos;s environmental restrictions. Conventional smelting methods use a separate furnace for each process step. The TBRC process employs but one furnace. The Afton TBRC vessel measures 6.4 m in length and 4.3 m in diameter. The furnace is supported on a set of motor-driven rollers. These permit the vessel to rotate at variable speeds to 40 rpm. Rotation provides good mixing, high reaction rates, and effective heat transfer from the refractory sides to the molten bath resulting in a low thermal gradient. The furnace can tilt through a full 360° for charging, firing, and pouring. Smelting at Afton is accomplished in sequential fashion. Flotation concentrate and limestone flux are initially charged to the hot, empty vessel. Using the water-cooled, oxy-fuel lance, the initial charge is smelted. Once sufficient molten bath is obtained and slagging completed, the metallic concentrate is charged. Materials are charged through the water-cooled, variable position additive chute mounted on the TBRC

Jan 10, 1980