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By Paul Clayton

Case Study ? Site: BMA Saragi Coal Mine Queensland Australia ? Model: Marion 8050 ? YOM: Mid 1970s ? Boom: 97M ? Bucket: Original capacity of 100 Tonnes upgraded to 125 tonnes at time of filtration upgrade. ? Apps: Swing, Hoist & Drag Gearboxes ? Oil: Oil Castrol Alpha TT1200 Viscosity of 1208 cSt @ 40° C (104° F) 720ltr Oil Volume Trial and Installation Justifications ? To reduce gearbox overhauls. Typical schedule being 5 years. ? Bucket upgrade from 100 tonnes to 125 tonnes. Increased gearbox demand and stress. ? Increase of overhauls out to 10 years + ? Saving per Dragline estimated to be US$8-10M in downtime and maintenance if successful. ? In compliance with BHPBilliton Global Maintenance FLAC program ? Fuels, Lubricants, Air and Coolants ? Cost Justification ? Downtime: 4 days ? Lost production: $420,000 ? Cost of parts: $162,000 ? Labour and misc: $41,000 Gearbox failure cost $623,000

May 1, 2008

By Glenville A. Collins

IN 1932, Horace Onyett at Oroville, California, built a practical floating washing plant along the general lines as now known, using a 24 in. by 12 ft. trammel; it was fed with a ½ yard dragline bucket, rated then at 200 yards per day. Onyett dubbed his plant a 'Doodlebug' which name has clung to this type of operation ever since. In general, the 'Doodlebug' dredge is the outgrowth of the depression of 1929, wherein many dirt contractors had surplus idle equipment and a few of them ventured to use it for placer mining. Many such plants were impractical and poorly designed and adapted often to locations not suited to the purpose. However out of the general idea came refinements until today dragline dredging has a very definite place in the gold production of the world. Many of the early operators, being mainly contractors without mining experience or technical knowledge of gold saving, geology, or mechanical design, naturally went through stages of trial and error until a workable unit became standard practice. Credit should be given Bodenson Iron Works of San Francisco, who did a notable job of pioneering and building of floating washing plants; also, to Lord and Bishop, contractors of Sacramento, who were among the early operators, and to several others who built and rebuilt their plants until the weak spots were strengthened to take the beating required, and yet deliver a high degree of efficiency.

Jan 1, 1945

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 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 John D. Nelson, Clint L. Strachan

Drainage of tailings impoundments is a key issue for impoundment stability, water control, seepage control, and reclamation. Drainage control is an established operating practice where climate and site conditions permit, such as in South Africa and various mines in North America. In these areas, drainage control is primarily used to maximize tailings densities and to provide adequate impoundment stability. Drainage practices during operation also become an important issue when tailings impoundments are reclaimed. Time required for cover placement and post- reclamation seepage control depends greatly on the ability for tailings to drain and consolidate. This paper discusses drainage issues associated with gold tailings impoundments in terms of mechanics of saturated and unsaturated flow and experience with design and reclamation of tailings impoundments.

Jan 1, 1988

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 K Nesbitt

Draw control at Premier Mine is considered important to avoid conditions of isolated draw, which results in early waste ingress, compaction of the kimberlite ore and loss of ore reserves. The Premier Mine kimberlite pipe is unique in that the pipe is cut at a depth of 400 metres below surface by a 75 metre thick gabbro sill. All cave mining at Premier is below the sill and failure to exercise good draw control could cause early ingress of gabbro waste. Gabbro causes problems in the diamond recovery plant and the amount of gabbro sent to the plant needs to be closely monitored. Fortunately coarse gabbro fragments are easy to recognise in drawpoints. It was anticipated that only 85 per cent of available ore would be drawn from the blocks immediately overlain by the gabbro sill before excessive gabbro waste forced the closure of drawpoints. Data on tons drawn per drawpoint and loaded per LHD as well as the tons tipped per pass is gathered by the vehicle monitoring and control (VMAC) system and information recorded by the load-haul-dump (LHD) drivers. Draw control staff monitor drawpoints on a shift basis and record the occurrence, type and height of hang-ups. Information pertaining to the status of the drawpoint in terms of support, waste and availability is also recorded. A database has been compiled that has been used to analyse the overall pattern of draw control, the frequency of occurrence of different types of hang-ups, secondary blasting efficiencies and drawpoint and LHD productivity. The gabbro sill has provided a unique marker horizon that has allowed the arrival of rock from a level 100 metres above the production level to be recognised. Data shows that ore migrates extensively towards groups of drawpoints that are heavily drawn with many drawpoints more than 100 per cent drawn before gabbro waste was recognised. This indicates that an accurate mixing algorithm is essential for good draw control. Data on tons drawn, drawpoint availability, productivity and the occurrence of various types of hang-ups has allowed better control of the mining operation and provided data for planning future caves. In the BA5 mining block a drawpoint spacing of 22 metres, horizontally across the major apex, has still allowed drawpoints to be pulled to waste with no loss of ore. In the BB1E mining block the drawpoint spacing has been increased to 23 metres and no problems have been experienced to-date. Future initiatives centre on improving the data gathering integrity of the vehicle monitoring and control system and a linear programme that will optimise draw control and productivity.

Jan 1, 2000

By R. Mulyanto, M. Siray, A. Parhusip, F. Hartono

"PT Freeport Indonesia is preparing the Deep Mill Level Zone (DMLZ) mine to be the successor of the currently operating Deep Ore Zone (DOZ) mine. The DMLZ is block cave mine situated 500 m below the DOZ mine and approximately 1600 m depth from surface. Both of the block caving mines require draw point construction in the extraction level to extract the ore from caved area above. Learning from the experience in DOZ, the construction & maintenance of draw points in the production panels is a significant challenge in supporting consistent production.The average DOZ draw point construction duration is approximately 46 shifts per draw point. The time frame for construction is dependent on several variables; availability of the conventional forming system, material availability, and development tolerances. The repair of concrete floors and lintel sets causes production downtime. Reviewing the old DOZ draw point design, there is an opportunity to increase constructability, durability, and reliability of DMLZ draw points. This paper discusses how the DMLZ has improved draw point construction productivity and is on track to significantly reduce costs whilst increasing the quality by using the Six Sigma Improvement Method.Introduction The DMLZ Mine is part of the PT. Freeport Indonesia (PTFI) future Expansion to its underground mining complexes. It is the fourth vertical lift in the East Ertsberg Skarn System (EESS) deposit (Figure 1).Currently, it is under development phase.The DMLZ mine will be a block cave mine using an advanced undercutting method. The DMLZ extraction level will be approximately 1,600 meters below the surface on the 2570 level with column heights of roughly 500 m. The Undercut is on 2590 level, some 20 meters above the extraction level."

Jan 1, 2016

By M. G. Schulz

Mining of molybdenum at Questa, New Mexico has been accomplished by block cave methods since August, 1983. As caving progresses, a periodic geologic evaluation is made of the rock-types present in finger raises on the Grizzly Level of the mine. The production maturity of the cave can be monitored by relating this data to geologic cross-sections through the ore body. The draw point mapping program is a simple and effective tool that is used in making draw control decisions at Questa.

Jan 1, 1985

By Dalia. R. Mohamed, Hisham H. Hafez, Marawan M. Shahien

"Construction activities in major projects that involve deep excavations necessitate the use of vertical walls surrounding the construction site to play an important role as earth retention system. The walls are usually partially penetrating impervious walls which can increase the efficiency of the ground water control system that usually consists of number of partially penetrating wells. The analysis and design of such system requires 3D numerical simulation. The aim of this study is to develop simplified semi-empirical approach to analyze and design such system. The analyzed model is a single well in a square site that is surrounded by impervious walls along the perimeter of the site in an unconfined aquifer. The results of the parametric analysis are presented in this paper aiming to assess and understand the factors that influence dewatering in terms of ground water or drawdown profile surrounding the well. The parametric analysis is carried out using the 3D finite difference software. The parametric analysis comprises with more than 550 cases calculated. The study involved the parameters; well penetration depth, impervious wall penetration depth, size of the construction pit, coefficient of permeability, well yield and well location or distance between well center to impervious wall edge.IntroductionThe presence of groundwater in a site may have impact on the construction processes involved during the course of project construction, especially those projects that involve deep excavations. Deep excavations, especially in urban areas, require the construction of supported walls all around the site perimeter to ensure the stability of the excavation. In most of cases, the constructed walls are relatively impervious. Depending on the ground and site conditions, the walls are not penetrating all the way down through to the bottom of the aquifer and thus the walls are partially penetrating walls. The presence of ground water necessitates the lowering of the groundwater to levels below the bottom of the excavation to ensure working in dry. This paper focuses on groundwater control systems that consist of deep wells inside square areas enclosed by impervious walls partially penetrating unconfined aquifers. The wells are partially penetrating the aquifer, as well. There are many factors or parameters that are related to the configurations of the components of the system that may influence the drawdown of a well in such groundwater control system. This paper is a part of a comprehensive study that aims to development of a simple method for estimating the drawdown of dewatering system of the described configuration. In order to achieve such a major goal, a 3D finite difference model is developed for the problem in hand. A comprehensive parametric analysis was then carried out to investigate the influence of all the parameters on the drawdown of a deep well in such groundwater control system. This paper describes the problem, the model, the parametric analysis including the involved parameters. The paper, then, demonstrate the results of the analysis showing the influence of the studied parameters on the drawdown of a single well."

Jan 1, 2016

By E. Henderson, L. K. Daneshmend

Drawpoint control is critical in determining the cutoff point for load-haul-dump mucking operations to minimize dilution. It is also necessary to ensure even mucking distribution and to prevent possible hang-up of material within a stope. A prototype production monitoring and reporting system has been developed for load-haul-dump operations in under-ground mines. The system generates accurate and timely information regarding mucked tonnages and drawpoint and ore/waste pass utilization. The monitoring system integrates a PLC-based load weighing system with a radio frequency identification (RFID) system for locating the vehicle. The system records the identification and time of entry and exit of each draw-point and ore/waste pass visited during a shift, as well as the weight of each bucket load. A trial of the system was conducted at the CAN-MET Experimental Mine near Val d’Or, Quebec. The monitoring and reporting system functioned as designed, with the exception that the maximum read range of the RFID tags under dynamic conditions was found to be a limitation. RFID systems with greater range capabilities have been identified for a second generation system. The system is the first of its type in North America to demonstrate that RFID tagscan be successfully applied to locate trackless underground equipment. Because of their ability to locate equipment and personnel within underground mines, RFID systems should be considered a key technology for future mine information and process control systems.

Jan 1, 1996

By T. Good

Twin roll sizers are neither compactly designed machines nor are they configured to accommodate underground mobility; in fact, twin roll sizers leave room for improvement in many aspects of the design. The DRC1200 capitalizes on the weaknesses of these machines to make a more productive, easily maintained, and compact twin roll sizer than current market offerings. These strides were made through the inception of the Hard Rock Extraction System (HRXS), which requires a mobile sizer as part of the system. After use of a third party sizer on the HRXS, potential improvements were evident. These improvements include improved structural design to reduce overall footprint and an optimized design to reduce operating cost.

Feb 23, 2014

By P A. Kirsch, A Hine

Mining is a major global industry that requires the moving of considerable volumes of earth and rock (overburden) to win the valuable ore prior to mineral extraction and processing. As a result of this process, new landscapes are created, both extracted voids and overburden piles, as well as infrastructure for management of mine operations, wastewater, tailings, other raw materials, transportation and extreme rainfall events. Resource companies must develop and obtain regulatory approval for detailed plans that manage this displaced material through all phases of the life-of-mine and rehabilitate the site at the time of closure (including landform stability, revegetation and ongoing management).Individual mine sites operate in long time frames (ten to 50 years), with several mines often operating in the same region, generating cumulative overburden volumes and heavily altering the original landscape. These impacts are universally framed as a negative consequence of the industry, especially by modern society that values natural (and some agricultural) landscapes as pristine and almost sacred. Overburden and tailings are also seen as a problem, and are a significant business cost to mining practice.This paper looks to investigate perceptions of mining and post-mining landscapes, questioning the aesthetically driven emphasis on the ‘natural’. It proposes instead an opportunity to reframe the way we look at overburden and landscape impacts from mining, exploring the possibility of imagined post-mine landscapes unburdened by traditional aesthetic expectations. These landscapes, to be conceived by regional stakeholder roundtables, have the capacity to be built by regional mining consortia as a foundation for sustainable post-mining economies.Post-mine regeneration offers both the motivation and the basic materials to create an altogether new environment from a blank slate. Few circumstances allow the opportunity to truly explore a re-envisioning of the land on a huge scale, and the possibilities merit serious consideration.CITATION:Hine, A?and Kirsch, P?A, 2014. Dreams of futures past – curating post-mining landscapes, in Proceedings Life-of-Mine 2014 , pp 121–138 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By J Stipcevich, N Patel, J Faithful5, S Narendranathan, L Tatnell4

ENGIE, the current owner and operator of the Hazelwood Open Cut coalmine, are in the process of rehabilitating the mine site in preparation for mine closure. Bucket wheel excavators (dredgers) used during coal mining operations are in the process of being demolished, which involves the controlled felling of dredger components using explosives. With the mine located in close proximity to the Morwell township and other critical public infrastructure, it is crucial that the use of explosives and the possible implications for mine stability is well understood. The felling of Large Mining Equipment (LME) will apply an impact load immediately to the underlying coal benches with the adjacent coal batters potentially at risk also of adverse slope stability impacts. This paper presents the 3D stability modelling methods employed to successfully assess the potentially adverse stability implications associated with LME collapse.

Jun 21, 2022

By Ronald C. Askin

Dredging is a common method of remediating ponds containing contaminated wastes. However, dewatering of the dredged solids is usually not well integrated with the dredging phase. As a result, overall project efficiency can be poor. Specifically, since dredges deliver material in a widely varying slurry form and since dewatering presses require the delivered material to be uniform, union of the two systems often results in inconsistent operation of the overall process. In an effort to enhance overall dredging and dewatering process production rates as well as minimize the return of suspended solids in the decant water, a new process was developed to provide a consistent dredged sludge for delivery to the press. This paper discusses modifications made to a conventional dredging and dewatering process to improve production rates and dewatering capabilities. These modifications are applicable to any project where efficient solids dewatering is required and where returning decant water must be visually free of suspended solids.

Jan 1, 1996

By S H. Burgmans, B Anderson

This paper aims to define the specific challenges relating to dredging fine tailings from an above ground storage facility for transferral to a mined-out pit. In addition, it compares dredging and mining perspectives on dredging of fine tailings.

Jul 1, 2021

By J. C. Boswell, J. D. Crawford

IN addition to its base-metal and coal mining operations, the United States Smelting Refining and Mining Company has, for the past quarter century, been one of the few large American mining companies interested in dredging. Its activities in this field are confined to gold, and to Alaska, but it is the largest operator in that territory, with twelve huge dredges available to work during the summer on the frozen ancient beach sands at Nome and the gravels of Fairbanks. These operations will be described separately.

Jan 1, 1948

By P. K. Sims

One-day field trip via U.S. Highway 6 and Colorado Highways 119 and 279 from Golden, Colorado to Idaho Springs. This field trip provides an opportunity to observe aspects of the Laramide ore deposits in the Central City and Idaho Springs mining districts and the Proterozoic basement rocks, which host the ore deposits.

Jan 1, 1986