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By T. M. Plouf, G. A. Lang

INTRODUCTION The finding or acquisition of ore bodies containing 200,000 opt gold and greater is becoming more difficult. There are more investors and small heap leach operators who have or can raise the capital to make the investments in the large ore bodies. Echo Bay Mines' approach has been to regionally develop small ore bodies, two or three in the same geographic location, which when considered together contain over 200,000 opt gold. CONCEPT The "world class" ore body syndrome, which many large gold producing companies maintain, can restrict company growth if the finding or acquisition of these large ore bodies is not forthcoming. Another approach has been taken by Echo Bay Mines. The concept is to regionally develop two or three small ore bodies suitable for processing with portable equipment. The systematic scheduling of mining, processing with a single flexible processing plant using the same management/ operator team can reduce your overall investment. The initial selection of mining and crushing equipment suitable for sun11 open pit operations is essential. A very viable option in the mining sequence is to use contract mining/crushing/screening/agglomerating and stacking. This option also lowers your initial capital investment and increases the flexibility in mining as you move from one mining operation to another. LOCATION AND SEQUENCING One single small ore body of itself is not attractive enough for the large producer. The recovery of the initial capital investment, although very rapid, does not make a viable project. The only alternative is to find two or more small ore bodies close enough geographically to each other so that the same management/operator team can be used to run the operations as each is put into operation. Echo Bay Mines has regionally located several ore bodies ranging in recoverable ounces up to 100,000 oz. These small separate ore bodies, located within a 30-mile radius of each other, for planning purposes have been considered as one single ore body. The first small ore body has the initial burden to recover the capital invested in the office, laboratory, power plant and processing plant. Other capital investments such as water supply, access and haul road, fencing, septic system, pads and ponds are reoccurring at each mine site. The first small ore body must recover the initial capital investment in the movable structures as well as the reoccurring capital investment in the fixed structures very rapidly. A total capital recovery time of 6 to 9 months should be used as an economic decision point for both choosing which small ore body should be processed first, and what the plant design capability should be. The sequencing of the small mines is very critical. All the fixed structures mentioned above must be installed at the second mine site before the first mine has been mined out. The ideal sequencing will allow for only one month between shutdown of the first small mine and production from the second. SPECIFIC OPERATION Echo Bay Mines has completed the construction of the Illipah Mine located in White Pine County, Nevada, with this small mine sequence approach. The Illipah Mine is a 40,000 ounce recoverable gold ore body. This ore body met all the necessary requirements. The Illipah project could support the capital investment in the movable structures which will

Jan 1, 1987

By George E. Aikens

Prolonged subzero climatic conditions impose some unique engineering problems for the developer and operator of open-pit mines in the Far North. The remoteness of the job site and the extremely cold, long, dark winters severely tax both man and machine in the quest for the Arctic's rich mineral wealth. Undoubtedly the singular most troublesome problem for the engineer is Permafrost which underlies about 201o of the land area of the world and about 85% of the state of Alaska. Permafrost has its impact on building construction and mine excavation, while posing a more pervasive threat to the-delicate ecologic balance within the Arctic wilderness. Yet the difficulties associated with mining up North may not be as overwhelming as has been previously supposed. For example, the lowest temperature recorded at Point Barrow is -560F, whereas Montana has recorded -69.7° F.. There are no specially designed machines for mining and construction in the Arctic, and efficient equipment utilization is maintained through proper operation and servicing techniques. However, neither equipment or people can be assumed to function normally at -40°F. Special techniques in drilling, blasting, and ripping are being used to yield economically competitive ores. Overall, a fundamental understanding of the nature of Permafrost will allow the engineer to deal expeditiously with an Arctic mining venture and at the same time to deal fairly with Arctic environment.

Jan 1, 1972

By Omar A. Muhtadi

6.1 INTRODUCTION The three most critical factors in successful heap leaching operations are: • The methods employed to pretreat ore (i.e, crushing and agglomeration); • Placement of ore on the leach pad (heap building techniques); and • Wetting of the ore with cyanide (solution application techniques). Improper execution of any of these initial steps may result in a substantial sacrifice of total metal extraction or, in the worst case, in project failure. Ore preparation in terms of crushing and agglomeration was discussed in Chapter 5; this chapter therefore focuses on commonly employed techniques for heap construction and solution application. The main objective of heap construction is to obtain the most homogeneous heap possible. "Channeling" of leachate in heaps with preferential seepage paths leads to preferential leachate distribution and uneven/incomplete extraction. The two main contributing causes of channeling are inadequate attention to heap construction and uneven solution application. These pitfall s can best be avoided through a knowledge of the various techniques available and the applicability and success of these techniques with various ore types and site conditions. The remainder of this chapter provides a discussion on these two subjects. 6.2 HEAP BUILDING TECHNIQUES Successful heap building techniques vary with the type of ore and, since no two orebodies are exactly alike, some slight modifications are usually necessary for each specific project. However, it is possible to generalize in terms of the appropriate techniques to be used with ores having similar characteristics. This section discusses the three most commonly used methods of heap construction and provides some guidelines with regard to ore types, construction constraints, and lift height parameters for each of the three. 6.2.1 Run-of-Mine Dumping and Dozing The run-of-mine method of heap building can only be used with ore of a highly silicious nature (i.e., ore which will not generate a large amount of

Jan 1, 1988

By Keith G. Wallace, Oscar Codoceo

This paper describes the ventilation planning that was per- formed at the Barrick Gold Corporation, El lndio Mine. The El lndio Mine is located at an elevation of approximately 4,000 m in the Andes mountains east of the coastal city of La Serena, Chile. The ventilation planning program consisted of a detailed ventilation survey of the mine and the establishment of a correlated com- puter model. A series of network simulations were conducted to determine the optimum position, size, and configuration of new ventilation raises and main fan exhaust system. Modifications to existing mine infrastructure including; driving of drifts, slashing of airways, and positioning of ventilation controls were examined. Detailed costing information was developed to optimize the location of the new main exhaust raises and fan system. The final ventilation system is expected to increase the mine airflow from the existing 157 m=/s to over 315 mls. This increase was necessary to accommodate an expansion in mine production, diesel equipment utilization, and deeper mine development. Furthermore, the increased airflow was required because of the de-rating of diesel equipment and large air volumes necessary to dilute diesel exhaust at high elevation.

Jan 1, 1997

By J. Gawler

In June 2005 the Minerals Council of Australia signed a Memorandum of Understanding (MoU) with the Australian Government which states an intention ?for mining companies and government to work together with Indigenous people to build sustainable, prosperous communities in which individuals can create and take up social, employment and business opportunities in mining regions?. Implementation of the MoU has begun with demonstration sites established across Australia. All sites are using a Regional Partnership Agreement (RPA) model as a framework for enabling local people to find local solutions to local issues in partnership with mining companies, governments and Indigenous communities. Mining and resources companies can provide important input into regional economic development and capacity building by working through local partnerships. Company benefits include gaining a social licence to operate, access to a reliable skilled workforce, better longterm relationships with Indigenous communities and sustainable regional communities. All levels of government, Australian, State and Local, are working collaboratively to address unemployment and other issues in remote Indigenous communities. The Australian Government has adopted RPAs as one mechanism for implementing its whole-of-government approach to Indigenous affairs. This leading edge work is unique to Australia and the model has applications and significant learning for other countries and industries.

Jan 1, 2007

By E. R. Hoskins

The Gulf Coast States ranging from South Texas to Alabama contain vast resources of lignite ranging in energy content from about 4000 to 7000 Btu/lb (as-received) with sulfur content ranging from about 0.5 to 2 percent. Currently, the strip mining rate is about 35 million tons per year in Texas and essentially zero in the other Gulf Coast states. Estimates of future mining rates are as high as 310 million tons per year by the year 2000 with 240 being in Texas. In this paper, we examine the life cycle of the surface mineable lignice based on the most recent estimates of surface mine recoverable resources with two scenarios. The first indicates that a 310 million tpy rate could be sustained for only 15 years while the second scenario suggests that the 310 million tpy could be sustained for 25 to 30 years. If lignite resources are required beyond those that are surface mineable, the deep basin lignite will be developed. Five strategies for developing deep basin lignite are discussed.

Jan 1, 1983

By R. Reeves

Coal producers and utilities depend on automated coal blending systems to reduce costs and meet stringent environmental regulations. Over 30 systems installed in the United States since 1987 use on-line PGNAA (Prompt Gamma Neutron Activation Analysis) analyzers to accurately control the blending process. Experience and detailed engineering are required to integrate real-time data produced by the coal analyzer with a control system to meet demanding performance specifications. This article reviews successful installations and lists important features including interfacing analyzers with plant control systems, specifying feeders and weigh scales, and managing data.

Jan 1, 1995

By C. M. Brown

The semi-autogenous grinding circuit at the Utah Mines Limited, Island Copper Operation, located on Vancouver Island, British Columbia, is described. Since start-up of the operation in 1971 grinding circuit throughput has been progressively increased from the initial design rate of 30,000 to the current average 45,000 tonnes per day (t/d) of porphyry copper ore. Key developments and modifications in operating and maintenance practice that have contributed to this increase are reviewed.

Jan 1, 1985

By R. C. Berry

The Environmental Impact Statement (EIS) has become a routine requirement for mining operations on federal lands. A similar document is being required in developing countries. Baseline studies are needed prior to writing an EIS and these studies involve surface water, groundwater, air quality, and wildlife/ native plant evaluations. The required baseline hydrology and geochemical studies are often the most expensive and lengthy evaluations. This paper summarizes the hydrology and geochemical baseline studies required for .An EIS and presents suggested methods to expedite these studies and to shorten the time and the cost to complete the studies and the EIS.

Jan 1, 1999

By F. G. Hyde

Passage of the Public Utilities Regulatory Policy Act ("PURPA") in I 978 created an entirely new industry that is referred to today as the Independent Power Producers ("IPP"). Requirements of project owners, environmental compliance, project design, the financial community and most of all, the need to be a low-cost producer presented a unique situation for the sourcing and the utilization of fuels. Depending on the specific type of project being developed, (e.g. coal-fired, wood/biomass, natural gas, petroleum coke or a blend of several fuel types) and the type of boiler design, it is important to acquire fuels that will optimize both the project's operating efficiency and flexibility. This paper will focus on the acquisition of fuel for coal-fired projects, but will describe the necessary steps in the sourcing, contracting for, and the utilization of fuels and transportation resources in the IPP industry today.

Jan 1, 1996

By Stefan Mede

Automation in segment production doesn’t necessarily mean the use of robots. Several other aspects of automation in the process are available. Herrenknecht has collected many experiences in the automation process of carousel systems for segment production, implemented several robot systems and launched new artificial intelligence-based camera system supporting the production team in the quality control This paper is a follow up of the presentation on Automation in Segment Production held in 2021 at the RETC.

Dec 1, 2022

By M. Saunders Macdonald

A number of open pit gold mines in Nevada extract ore from areas below natural groundwater elevations, necessitating dewatering and some method of disposal of the extracted water. These open pits extend well below the water table, with associated dewatering volumes greater than 10,000 gpm. Some mines, with large volumes of dewatering water to manage, have constructed re-infiltration basins to re-introduce dewatering water to the groundwater system some distance from the pits. This paper presents an overview of the state of the art of re-infiltration projects, including the permit process for such projects in Nevada, and the necessary engineering considerations.

Jan 1, 1996

By Nick Chlumecky

INTRODUCTION Column-type supports are used to prevent roof falls in underground excavations. The first individual column supports were made from timber that was cut to fit the irregular heights of mine seams. Because the seam height of the material removed varied throughout the mine, timber posts generally could be used only once. During the I 920s, steel friction props began to appear in British and European mines, and, by the 1950s, thousands of these props were being used. However, the steel friction props were heavy, difficult to install, and difficult to recover. Furthermore, the friction props could not be preloaded, and their yielding behavior was rather erratic. In 1946, hydraulic props were introduced in En¬gland, and, within a few years, they replaced friction props throughout Europe. The first application of hy¬draulic props in the United States occurred in the 1950s, during early experiments with longwall mining. Modern technology and high-production mining procedures have combined to make the use of hydraulic props a very acceptable method of providing temporary heavy-duty support for production areas. In areas such as development headings, where only modest roof loads are expected, lighter-duty jackscrews, ratchet jacks, and light hydraulic props are used. ADVANTAGES OF HYDRAULIC SUPPORTS The acceptance of hydraulic supports has been wide¬spread during the past 25 years, proving their reliability and effectiveness in preventing roof falls. Some of the advantages provided by hydraulic supports are: 1) Individual hydraulic props can be installed within 30 sec, resulting in a minimum exposure of per¬sonnel and equipment to an unsupported roof. 2) Hydraulic props can be preloaded to more than 4.5 t (5.0 st), increasing the frictional resistance between the rock strata. Thus, the roof is kept tight, improving the behavior of the unsupported ground. 3) If gradual roof sagging or bottom heaving im¬poses an irresistible force, the hydraulic prop yields gradually and continues to support the ground. 4) The support capacities of the hydraulic props most widely used range between 10 and 20 t (11 and 22 st). Their support capacities are maintained during yielding to an irresistible force. 5) Hydraulic props can be recovered rapidly. Where no other supports are provided for the roof, as in pillar¬ing operations, the hydraulic props can be recovered by remote means. 6) The length of hydraulic props is readily adjust¬able allowing them to be reused in seams where roof height varies. 7) Studies of mining operations indicate that the use of hydraulic props increases both personnel safety and mine productivity. DESCRIPTION Figs. I and 2 illustrate typical hydraulic props used in mines in the United States. Fig. I illustrates a prop

Jan 1, 1982

By T. F. Deems

The nature, usage and comparatively rare occurrence of ball clay is described. The importance of these white firing plastic clays in ceramics, particularly in the production of industrial sanitary ware and tiles, is emphasized. The US deposits are briefly discussed. What is known about relevant deposits in Brazil, Argentina, Colombia and Venezuela (the four largest ceramic producers in South America) is also described. The ceramic plants have been sited near the centers of population rather than the plastic clay deposits. At present, extraction is probably concentrated on surface residual deposits and lenses which require minimum investment. Native plastic clays are used exclusively in the tile plants, but in sanitary ware, they are often used as extenders of imported ball clays.

Jan 1, 1997

By N. P. Titkov

This paper presents the results of laboratory and pilot plant investigations for the development of efficient methods of beneficiating hematite ores from the Krivoi Rog, Kursk Magnetic Anomoly, Olenogorsk, and other localities. The tests included gravity, magnetic (in a high intensity field), flota¬tion, and magnetizing roasting methods. It was possible to develop efficient beneficiation methods depending on the mineral composition of the ore and degree of dissemination of ore and gangue minerals. The paper shows the relationship between the iron silicate and quartz content of the ore and the technologic indices of the various beneficiation methods. Some of the conclusions based on these investigations and the technical and economic computations related to the cost of one ton of pig iron produced from concentrates obtained by the various beneficiation methods are: 1. If the hematite ore is not disseminated uniformly, it is expedient to use a combined gravity and flotation process. Ore particles up to 50 am. in size are beneficiated by gravity (heavy suspension, jigging, and others) and yield a lump concentrate. The middlings from this process are recrushed and floated; 2. Finely disseminated hematite ores, containing small quantities (less than 5 percent) of iron silicates, are most effectively beneficiated by flotation. Anionic (sulphate soap, tall oil emulsion with various foam depressors) as well as cationic collectors may be used. Depending on the mineral and chemical composition of the ore, it is possible to obtain concentrates containing up to 65 percent iron with an extraction up to 94 percent; 3. Finely disseminated, mixed hematite-magnetite ores may be beneficiated by flotation or a magnetic separation-flotation process; 4. Finely disseminated hematite ores, containing large quantities of iron silicates and earthy hematite ores are most efficiently beneficiated by the magnetizing roasting method. This method will yield concentrates containing up to 68 percent iron with extractions up to 90 percent. Although beneficiation by the magnetizing roasting process is costly, it will nonetheless, when employed on this type of ore, yield the least expensive pig iron.

Jan 1, 1960

By Christopher Laughton, Michael P. Bruen

At Fermilab, a 4000-ft long underground complex has recently been constructed for a high-energy physics experiment. The complex is sited up to 350 ft, below grade principally in bedrock. The rock excavations were mined by TBM and drill and blast methods and supported by a combination of rock bolts, dowels and shotcrete. Water control was achieved using a combination of pre- and post-excavation grouting, drainage systems, drip shielding and air desiccation measures.

Jan 1, 2003

By V. A. Scovazzo

The analytical pillar design procedure employing the Wilson equation is based on the site-specific material strength of the floor, pillar, and roof rock. Stable pillars so designed will sometimes be larger than those designed using empirical methods thus providing more stability or at other times smaller than empirically designed pillars thus conserving natural resources. Presented here is a detailed procedure for the analytical design of soft rock pillars using the Wilson Equation. An example of this procedure is presented that uses data from a mine in the Owl Seam in Southern Appalachia. These Owl Seam pillars are now in use and are performing as expected. Also addressed is an assessment of the Dr. Scovazzo?s analytically designed pillars based on pillar performance data gathered by Dr. Mark in the Southern Appalachian Coal Field.

Jan 1, 2010

By B. R. Pothini, H. von Schonfeldt

In underground coal mining many excavated openings have a relatively short projected life span. To ensure safety for men and materials at a minimum cost over the projected operating life, only pillars for overburden support and roof bolts for support of the openings are used extensively. Mining activity constantly changes the geometry of the mine producing load changes on the structural support members of the openings that often induce unstable deformations which can lead to roof falls or pillar failures. The paper describes how simple deformation measurements can be used to design primary and supplementary roof supports and to predict roof falls and possibly pillar bumps. Specifically, bed separations in the roof measured directly with the help of borescopes and calculated from differential convergence data are used to optimize bolt links or support requirements for chemical stabilization of mine roofs. Roof falls are predicted on the basis of admissible values for cumulative convergence between roof and floor, convergence rate, and the change of the rate of convergence. The pillar extraction operations convergence anomalies detected from contouring identify bump prone pillars, while convergence and pillar dilation determine the yield zone in a pillar to verify pillar softening and de-stressing. Manuscript not received in time for publication.

Jan 1, 1983

By B. H. Kim, P. Zhang, M. A. Van Dyke, D. Su, H. Dougherty

The National Institute for Occupational Safety and Health (NIOSH) has been evaluating longwall mining-induced strata fractures and their impacts on casing stability of Marcellus shale gas wells located in longwall pillars. To understand the extent of overburden fractures after longwall mining, NIOSH researchers drilled a postmining corehole into the fractured strata above the Pittsburgh coal seam longwall gob. Knowing the extent of the fracture zone height will help gas operators minimize the hazards of drilling into longwall gobs. The core was retrieved from the surface down to the top of the gob void. Various fractures were encountered varying from 35 to 64 degrees, depending on lithologic type and relative closeness to the gob. The longwall panel dimension was 457 m wide and 3657 m long, in which the total fracture zone height was found to be at 141 m and the hydraulic connected fracture zone at 87.7 m above the top of the Pittsburgh seam. In addition to core drilling through the gob, FLAC3D modeling was also used to simulate the formation of fracture zone and the orientations of longwall-induced fractures. This study provides much-needed evidence on the fracture zone of Pittsburgh seam longwall gobs to help gas operators avoid potential hazards associated with drilling through highly fractured zones

Mar 2, 2022

By D. M. Fritz

Environmental experts face large and rapidly-increasing volumes of raw data obtained from environmental monitoring stations. These professionals must compile and analyze the data in a systematic manner to cost-effectively understand and minimize the impacts of mining. The shift toward desktop computing, combined with the downsizing of company staffs, has now more than ever created a demand for a modern, PC-based application for the storage, retrieval, analysis and presentation of environmental data. This paper discusses the general requirements of such a system, and points out specific ways in which such industry-specific software can provide convenient and useful access to the data. The software used to illustrate these features is the HydroDat program, developed by Western Water Consultants, Inc.

Jan 1, 1996