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By William R. Nash

The scope of work for the fast track construction of the Weeks Island Replacement Facility, Weeks Island, Louisiana included the design and construction of two salt mines. Mine #1 - An interim underground mining level consisting of a 975 m (3200 ft) incline and 3520 m of 5.5 m x 7.3 m (11560 ft of 18 ft x 24 ft) drill and blast excavation; raise boring; core drilling; roadheader excavation; complete bulk material handling facilities utilizing an existing production shaft. Mine #2 - Simultaneous with the interim mine construction a new one million ton per year underground salt mine was constructed consisting of: two 5.5 m diameter x 381 m (18 ft diameter x 1250 ft) deep shafts; 76450 cu m (100,000 cu yd) of drill and blast bottom excavation; surface and undergound bulk material handling systems (conveyors, skip loaders, shaft equipment, hoisting); ground freezing for water control for both the production and service shafts; the design of the first underground doublewall slipform installation of a dynamic bitumen shaft lining system; the emergency grouting of both the existing production shaft and the interim mining level in the salt dome; 227 mt x 64 m (250 ton x 210 ft) high structural steel production headframe; 2.2 MW (3000 hp) double drum mine hoist; service shaft headframe; and service buildings.

Jan 1, 1987

By Wilhelm J. Kogelmann

The quest for U.S. energy independence will result in a major increase in underground mining operations. It will necessitate the rapid excavation of development drifts, entries and slopes to exploit underground deposits of energy resources such as coal, uranium and oil shale. Most of this development work will be done in soft and medium hard rock up to an unconfined compressive strength of approximately 20, 000 psi. OBSTACLES TO RAPID TUNNEL EXCAVATION Labor In the U. S. coal mining industry, the underground productivity in tons per man-day declined from 15. 61 in 1969 to 11. 00 in 1973 which is a startling 30% decline. While productivity declines, the cost of labor and supplies continues to rise. Ralph E. Bailey of Consolidation Coal Company recently stated four reasons for the decline of productivity: A shortage of experienced miners, enactment of the Federal Coal Mine Health and Safety Act effective April 1970, major changes in union work rules in 1968, and a deterioration in the attitude of the work force (1). Because there is already a great shortage of skilled miners, the situation will get worse when large new mines for oil shale, coal and uranium open in sparsely populated areas in the Western United States. Only the large scale use of easy to operate tunneling machines can increase productivity and lower the cost of excavation.

Jan 1, 1974

By G. R. Tostengard

Gold plant performance during the start-up period, which extends until capacity production is sustained, has a major impact on the internal rate of return and the net present value of gold projects regardless of mining and processing configurations. The start-up period experiences substandard production, extra expenses, and sometimes reduced recovery. This results in lost profits, a portion of which are recouped at the end of the life of the mine. Poor start-up performance can put projects into financial jeopardy. The gold mining industry regularly experiences start-ups ranging from good to poor. Problem areas, which affect start-up performance, include shortcomings in ore reserve sampling and testing, equipment design and installation, untrained plant operators, inability to cope with problems which arise, and organization of the maintenance program. An investment, equal to 0.5% to 1.0% of plant capital cost, in programs to prepare for start-up, in advance, is recommended. Investment in such a program will make a good start-up possible. Without it the best result which can normally be expected is a fair start-up. Developers of new gold mines are urged to compare the cost of this investment with the anticipated increase in project net present value. Funds for this investment should be included in feasibility studies.

Jan 1, 1988

By Samantha Smith

Nautilus is completing the world's first environmental impact assessment (EIA) of seafloor mineral extraction and Nautilus has gained extensive experience conducting environmental studies in subsea environments. Nautilus is currently working on the Solwara 1 Project in the Bismarck Sea, Papua New Guinea, where high grade seafloor massive sulfide deposits lie at ~1600 m water depth. Conducting an EIA in the deep sea presents some interesting and exciting challenges. Seafloor studies commenced in December 2005 using a remotely operated vehicle (ROV) fitted out with highly specialized scientific equipment to conduct water quality, sediment, biological and oceanographic studies. During 2007 and 2008, Nautilus launched two two 30-day ROV programs dedicated to environmental baseline studies and during this campaign, over 550 biological, sediment and water samples were collected and over 20,000 seafloor observations were logged. On board specialists included an international team of experts in the field of deep sea marine science. Collaboration between industry and scientific research institutions allows data to be collected for the EIA but also provides an extraordinary opportunity for researchers to access sites that might otherwise remain unobtainable to science. This presentation will review the studies conducted as part of this exciting project. Keywords: Seafloor Massive Sulfides, Environmental Impact Assessment

Jan 1, 2008

By Charles G. Zink

Early anthracite "deep mining" methods, production, manpower. underground transportation, labor, safety and reserves are reviewed and compared to the present and to future requirements which must be met in order to economically win the fourteen million tons of untapped reserves and to keep the product competitive in the market place.

Jan 1, 1971

By A. J. Neale

Much has been published lately about the application of advanced control strategies in the automatic control of autogenous and semi-autogenous grinding circuits. The application of adaptive control algorithms, self-tuning controllers, state estimation, and expert systems has been well documented. While these approaches can be very effective; experience has shown that quite often simply "fixing the fundamentals" can have a significant positive impact on overall grinding circuit performance. This paper will highlight the results of process optimization and process control work by the authors at a variety of autogenous and semi-autogenous installations. A review of one approach for quantifying the mill load/bearing pressure/power relationship is provided. Accurate monitoring of key mill process variables is a necessary prerequisite for both effective process analysis and process control. This paper discusses some of the concerns related to defining steady state operating conditions and the issues related to signal conditioning. The paper concludes with a discussion of an effective application of algorithmic constraint control which incorporates many of these considerations.

Jan 1, 1994

By R. L. Sundeen

Trackless vehicles, as the name implies, are machines not bound to rails, guide cables, or other direction controlling devices. They include, for the most part, vehicles which are wheel or crawler (track laying) mounted. Power sources may be self contained such as diesel or battery and can be defined as non-captive machines, while connected power sources such as compressed air or electric can be defined as captive machines. Trackless vehicles are used in all phases of underground excavation, loading, hauling and dumping. Early application found most machines with digging ability used to load those with payload hauling ability. As the versatility of trackless methods became more obvious the trackless vehicle has evolved to more productive machines such as the self loading haulers commonly referred to as Load-Haul-Dump equipment. Trackless vehicles find wide use in drifting and tunneling. Ability to negotiate adverse grades is especially noteworthy. Experience drawn from highly efficient room and pillar mining operations has lead to relatively wide application in drawpoint and cut and fill mining.

Jan 1, 1969

By F. W. Brackebusch

Paste is a high density mixture of water and fine solid particles with a relatively low water content (10-25%) such that the mixture has a consistency as measured by the ASTM slump cone test from slightly greater than zero up to nearly 12 inches (305mm). Particles of different size classes will not segregate or settle when the paste is not being agitated or when it is stationary in a pipeline. Cement may be a component of paste. Larger particles of aggregate can generally be added to a paste without greatly changing the pipeline transport characteristics. A paste may bleed water slightly when it is allowed to be motionless for periods of up to several hours, but the solids do not become so dense that the paste cannot be easily re-fluidized. The dividing line between the definition of a high density slurry and a paste is not sharp. It is a practical matter that must be considered when designing a pipeline transportation system. If the pipeline is very short, there is very little risk of plugging the pipeline with a high density slurry when flow is stopped for short time periods. With longer pipelines the mixture must remain stable without motion for periods as long as several hours to avoid pipeline plugging. The fine particles in a paste mixture can be composed of mine tailings or naturally-occurring clays, silts and fine sands. The mineralogy of the particles thus can have a wide variety from quartz and feldspar to clays, micas and even salts.

Jan 1, 1993

By C. A. Fleming, C. J. Ferron, E. S. Makande, P. Mason

Several small mines are producing refractory gold concentrates in Zimbabwe and, owing to the small scale of most of these operations, their output is processed in a central custom roaster in Kwekwe. Owing to the wide variations in the feed to the roaster, the efficiency of the old Edwards roaster is deemed unsatisfactory with gold recovery from concentrate as low as 70%, and alternative processes were evaluated to improve this situation. Various processes for oxidizing refractory arsenopyrite/pyrite concentrates to liberate gold prior to cyanidation are known. In practice, only two have to date met with wide industrial acceptance, pressure oxidation and roasting. Owing to the ·high arsenic and antimony levels of some concentrates in Zimbabwe, the only viable roasting alternative would be two-stage air-roasting of concentrates in two reactors, as practiced at Giant Yellowknife, Campbell Red Lake and New Consort. This process, however, creates an arsenic disposal problem, and produces gas of fairly low SO2 content, requiring a large gas handling system for acid production. On the other hand, there are currently four commercial pressure oxidation plants treating refractory gold ores (McLaughlin, Mercur, Getchell and Goldstrike) and three treating concentrates (Sao Bento, Porgera, Campbell). One other concentrate oxidation plant is being constructed (Con), and several more are being considered.

Jan 1, 1992

By P. T. Brown

Denison Mines Limited, Canada's largest uranium producer located in Northern Ontario recently embarked upon an extensive development program that would allow them to substantially increase production and also meet the more stringent air quality standards established by the ministry of Natural Resources. To proceed with this program it was essential that the fresh air supply be greatly increased to the underground workings. A major portion of the mining area is located under Quirke Lake on the north limb of a syncline termed the Quirke Lake trough. The Denison engineers determined the most practical size and location for a proposed new fresh air shaft, eventually deciding to drive a 25 foot diameter shaft, 490 square feet in section for 1,800 feet long vertically. The shaft collar would be located on Roman Island, an island in Quirke Lake. A test hole was drilled from Roman Island to determine the ground through which the ventilation shaft would pass. This drill hole confirmed the location of the Quirke Lake over-thrust fault, a highly fractured water bearing zone 165 feet thick, approximately 800 feet below surface. Plans were made by Denison Mines Limited to seal and consolidate this ground when it was encountered by the shaft.

Jan 1, 1974

By Reinhard Gnilsen

Ground pillar control in soil and weak rock often represents a critical and sometimes a determining factor for mined underground civil structures. A concept is desirable that minimizes the restrictions possibly imposed by pillar control requirements on geometrical tunnel characteristics and on the mining operation itself. Conventional concepts are discussed and an alternative concept is introduced. This concept reduces pillar control requirements to ground control measures required with "regular" tunnels. The conventional model of pillar mechanics with potential yielding of a ground body in more than one direction, is then avoided. Due to the complexity of pillar mechanics, the level of engineered design furnished to the contractor is crucial to optimizing ground pillar control. Conventional versus alternative contractual arrangements for pillar control are described and their important role is illustrated. The concept introduced relates to principles inherent to the New Austrian Tunneling Method (NATM). However, tunnel projects using other mining concepts can employ alternative ground pillar control principles as well, if certain criteria are observed. Case histories in the United States and abroad are presented and the impacts from different concepts of ground pillar control are illustrated. The paper concludes by analyzing concept characteristics that can infer monetary impacts on both the owner and the contractor.

Jan 1, 1987

By T. B. Szwilski

The paper gives an account of the development of a mine health and safety program in China from 1987 to 1996. The project was funded by the United Nations Development Program and managed by the International Labor Office (ILO). The objective was to strengthen the capability of the National Safety Training Center (NSTC), located near Beijing to train more than 2,000 engineers per year, and provide consulting and informational services to 39 safety training centers and coal mines. Presently China has the highest mortality rate in the world for coal mine operations, the greater incidence occurring at the many thousands of small, unlicensed underground mines.

Jan 1, 1998

By J. Fox, C. Allen, A. Greth, K. Kocsis

"It is the duty of the mine operator to ensure the mine environment is healthy and safe for the mine workers. For deep and hot underground mines, this requires maintaining adequate working temperatures by means of mitigating the heat load generated by strata, auto-compression, mining equipment, explosives, ground water, and human metabolism. The heat load is best reduced by minimizing the amount of heat transferred to the mine air from these sources and through the use of efficient ventilation with effective cooling systems. The heat emitted by mining equipment and vehicles contribute a significant proportion to the combined heat load of an underground mine. This is especially a problem for diesel equipment due to the fact that besides heat, a large amount of water vapor is produced, which increases the humidity in the production workings. Diesel engines have proven advantageous in recent history due to their high power output and reliability. However, as mines continue to become more mechanized and deeper the climatic problems introduced by elevated heat generation will continue to rise. With that, the issue of heat generated by diesel equipment must be addressed. The economic alternative for diesel engine equipment fleets in underground mines is the electric engine. Technological advances in battery technology, increased mechanical output and improved reliability have made the electric engine significantly more competitive in comparison to diesel engines. Because electric engines do not utilize internal combustion, the heat produced by them is significantly less than of the diesel engines. Battery powered mining equipment likewise eliminate diesel particulate matter (DPM) produced by diesel engines. Utilizing battery electric equipment in underground mines provides many advantages, such as: (a) reduced heat load, (b) healthier and safer environment for the mine workers, and (c) reduced mine operating costs due to lower ventilation requirements. This paper will highlight the health and cost benefits of using battery/electric fleets versus diesel fleets in deep and hot underground mines. The study analyzes simulations produced from thermodynamic ventilation models. Early simulations show significant cost reductions in terms of net present value (NPV) when comparing the air volume requirements for battery/electric equipment versus diesel powered equipment for the same production rate. INTRODUCTION The competitiveness of the world mineral market demands that mine operators continue to increase production and decrease costs as commodity prices fluctuate in often unplanned directions. This has forced underground mines to operate at deeper depths and to become more mechanized to remain competitive. Because of these changes, ventilation challenges have continued to increase as the mines combat an enlarged influx of contaminants such as heat and diesel particulate matter (DPM)."

Jan 1, 2018

This United States Bureau of Mines study is based on a review of U.S. mine fire accidents that occurred from 1970 through 1989. Information on these accidents was obtained through investigative reports written by Mine Safety and Health Administration personnel. For this study, 260 mine fire accident reports were examined. A previous Bureau research effort established that fires causing fatalities were more likely to occur in haulage entries than at any other underground location. This study has found that the most prolific source of haulage entry fires was the inadvertent grounding of trolley wires. The largest segment (15 out of 40 trolley wire fires) resulted from not maintaining adequate clearance between the trolley wire and the vehicle. Several novel fire prevention and control ideas have evolved in response to frequently occurring fire-related problems. These included; discriminating power isolation devices, wire cutting devices, more accessible fire extinguishers, vehicle overcurrent protection, and vehicle fire suppression.

Jan 1, 1994

By Dion Weatherley, Raúl Castro, Pablo Cid, René Gómez

In underground mining, hang-ups due to coarse fragmentation are frequently observed in drawpoints, drawbells, and ore passes during ore draw. Hang-ups can often require operational interference and hang-up removal activities. Drawpoint and drawbell design has been shown in some studies to influence hang-ups; however, the full extent of this influence remains open to question. In this study, the discrete element method was used to analyze the effect of hang-ups on three distinct drawbell geometries: the Drawer type, Circular type, and El Teniente type. The drawer type was used as the base case given that data was available from a physical model in which hang-ups were studied. The drawer type base case data was then used to calibrate our numerical model. Results show that the El Teniente drawbell geometry sustained 13% more hang-up events as compared with the base case, while the circular drawbell geometry had 16% fewer hang-up events than the base case. From this study, it can be concluded that fewer hang-up events will occur with a rounded drawbell geometry.

Apr 11, 2023

By Robert C. Sutter

In 1958, it became obvious to some of us in the solution mining business that there were certain problems in connection with our sodium chloride brining operations which were industry- wide. These were the types of problems which, while they were important to the safe and economical operation of our salt brining operations, were not such that their solutions would give an individual company a great competitive advantage over his competitor; and since they involve the safe and efficient mining of a natural resource, it was obvious that the answers would, in any event, be shared industry-wide. Since we were dealing with underground solution mining and, consequently, unseen and remotely controlled operations, the problems are formidable and the solutions difficult. While all of us were doing work to improve our operations, none of us could justify the expenditures necessary for basic research in these areas. Consequently, the idea was conceived of research sponsored by many companies with the same problems. In 1960, 11 companies entered into a' formal agreement to jointly support research on a specific problem of sodium chloride solution mining. The project to be undertaken was the development of a method for measuring the size and extent of underground solution cavities in sedimentary salt beds. It was agreed that all research was to be performed by independent research organizations. A part-time consultant or administrator was retained to administer the research contracts and to provide technical advice.

Jan 1, 1966

By Rick Bearce, Minsu Cha, Mike Mooney, Yuanli Wu, Lisa Mori

"Proper soil conditioning is critical for effective earth pressure balance (EPB) TBM tunneling. Chamber pressures can reach 3-5 bar yet the vast majority of testing is performed under atmospheric conditions. This paper illustrates how pressure influences foam stability and conditioned soil behavior, and how atmospheric test results must be viewed in the context of expected chamber pressures. Torsional shear strength, compressibility and abrasivity of foam conditioned sand were found to be ideal when the void ratio was above the ASTM-determined maximum void ratio, achieved by sufficiently expanding the soil grain structure with foam, herein when the foam injection ratio at pressure exceeded 45%. Otherwise, the engineering properties of foam conditioned sand were not ideal, i.e., appreciable torque and abrasivity, low compressibility. INTRODUCTION Proper soil conditioning is critical for effective earth pressure balance (EPB) TBM tunneling. The formation soil at the cutterhead must be transformed into a highly compressible, low shear strength and low permeability medium within the excavation chamber to allow effective EPB performance. This behavior must be maintained for a certain residency time while the soil is in the chamber and screw conveyor. The vast majority of published studies on conditioned soil behavior have been performed under atmospheric conditions (Quebaud et al., 1998; Bezuijen et al., 1999; Psomas and Houlsby, 2002; Vinai et al. 2008; Thewes et al., 2012; Peila, 2014); however, the desired soil behavior must occur under chamber pressures that can reach 5-7 bar. The influence of pressure on conditioned soil is significant and is dramatically different than behavior under atmospheric pressure (Williamson et al., 1999; Mori et al., 2015). This paper illustrates how pressure influences conditioned soil behavior and how atmospheric test results must be viewed in the context of expected chamber pressures. The influence of pressure on foam bubble size (including with time) is shown through digital image analysis. The influence of pressure on foam half-life is also investigated. The compressibility, shear strength, and abrasivity of conditioned soil under pressure is presented and explained in terms of density, soil and air compressibility and porosity."

Jan 1, 2016

By Harry R. Dahlberg

Heap leaching is discussed as a unit process. Five factors are identified as the principal elements that can be measured and/or controlled. These are: 1. Material Size 2. Volume of solution 3. Tonnage of heap 4. Time 5. Solution concentretion. The Rate of Extraction Curves obtained from an actual heap or column tests describes the economic viability of the unit process. By analysis of these curves and the five factors end their inter-relationship it is possible to determine how the extraction rate can be increased. The practice of leach and rest used by many operators is analyzed and shown on a hypothetical rate of extraction curve. The influence of the driving force of the hydrogen ion and ferric Lon as Lixivants and its effect on the rate of extraction curve is discussed.

Jan 1, 1979

By T. L. Myron

In recent years increasing attention has been given to improving both the chemical and physical properties of sinter. The first step toward this goal was the production of a self-fluxing-sinter. More recently, blast-furnace operators have found that significant improvements in blast-furnace performance can be achieved by improving and controlling the physical size of the sinter. The results of full-scale blast-furnace tests have shown that blast-furnace production can be improved by using a closely sized agglomerate. The improvements obtained by the use of pellets, a closely sized agglomerate, are well known. In contrast, blast furnaces charged with sinter having a wide size spectrum have generally not yielded results as satisfactory as those from furnaces 1) * charged with pellets. Beginning in 1958, Appleby-Frodingham charged plus 3/8-inch sinter to their blast furnaces. Further tests by other companies in Canada, 2) the United States, 3) and Australia showed that blast-furnace production could be improved by about one percent when the plus 3/8-inch material in the burden was increased by one percent. Because of the promising results obtained with screened sinter, an extensive test program was initiated to determine an effective means of producing sized sinter in U. S. Steel's sinter plants. This paper describes the work done by the Applied Research Laboratory in this program.

Jan 1, 1965

By K. F. Unrug

The research work reported in in this paper deals with the monitoring of roof behavior in a drift mine located in Eastern Kentucky operating in the Coalburg Seam. The thickness of the seam at the monitoring site ranges between 9 and 10 feet with the immediate roof changing from sandstone to shale then back to sandstone. Shale thickness varies between 0 and 2.5 feet. The characteristics of the immediate shaly roof were monitored with 38 dynamometers which were set up in three survey lines to cover the entire range of shale distribution. The dynamometers are capable of providing accurate load readings in the range of +/- 5 pounds. To closely observe the contribution of moisture toward roof deterioration the dynamometers were set up in intake and neutral airways. A television borescoping camera was used in conjunction with the dynamo- metric instrumentations at pre- determined observation holes to physically observe and record the separation process of the shale and sandstone stratum with respect to time. Monitoring took place between January 1985 through January 1986 in order to cover a full cycle of dry and wet mine conditions associated with the seasonal changes. Analysis of the data show a trend of roof deterioration induced by condensation and eventual penetration of moisture within the immediate roof bedding planes, leading to rapid disintegration of the mine roof.

Jan 1, 1986