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By W. K. Summers

During the past few years monitoring systems have been installed to measure the effects of environmental changes on the ground-water resource. The design of a monitoring system depends upon the designer's perception of how the environmental factors merge with his perception of the ground-water flow system. The validity and representativeness of measurements made during a monitoring program depend upon the validicy of the designer's perceptions and concepts. To optimize the design of a ground- water monitoring program the designer should make preliminary measurements to confirm his assumptions.

Jan 1, 1985

By Jose Agapito

Roofbolts with expansion anchors have been used at White Pine for more than twelve years, but always with an understanding that their performance was not entirely satisfactory. Some bolts fell out, some were obviously loose, and, when roof failures did occur, very few bolts actually broke. Obviously, there was an anchorage problem. A program was started in May, 1967, to define the problem and to solve it. This paper describes briefly those parts of the program which led to the development of a roofbolt assembly which performs much better in the medium-hard rocks at White Pine. As a result of the changes, significant improvements were found in the torque:tension, tension loss, and pull tests.

Jan 1, 1970

By Saman Khaleghparast, Naj Aziz, Jan Nemcik, Guanyu Yang

"More than 25 years of uninterrupted research on ground support technology for underground mines has been undertaken at the University of Wollongong. This research has resulted in significant findings on tendon characteristics and strength properties. The paper focuses on the development of the fourth generation of cylindrically shaped shear test apparatus for assessing tendon performance in shear. This shear apparatus is known as the MK-IV Double Shear Box or Naj Aziz Double Shear Box (NADSB), and is based on the experience gained from the development of previous versions of rectangular double shear boxes. The new NADSB is circular in shape and is fitted with a truss system, which permits friction free shear testing of tendons across joint planes. A series of double shear tests were carried out on a number of cable bolts commonly used in Australian mines, both plain and indented wires, under varied pretension loads. The results were compared with similar test results using rectangular shaped double shear apparatus, with and without friction across joint faces. The significance of wire surface roughness and increased initial pretension loads are discussed and conclusions made, suggesting that indented wires are inferior in shear compared with plain cable bolts. The general test procedure of the NADSB is described and different concrete reinforcement techniques are reported. The influence of external and internal confinement of the concrete medium blocks in a circular double shear box contributed to consistent test results with a minimum of lateral and axial cracks occurring in the host medium.INTRODUCTIONThe use of long tendon ground support elements (cable bolts) is now a common practice in modern underground coal mines, hard rock mines, tunnels and other underground structures. Due to their material properties cable bolts contribute significantly to the overall ground reinforcement provided by a support system. Cable properties in tension and shear are in many cases vital to maintaining a safe and productive underground environment. Accordingly, tension and shear properties must be assessed accurately using both valid and reliable methods.Load transfer property testing of tendons has been studied over several decades with much of the early research focused on the pull and shear testing of solid rock bolts and hollow bolts (like Swellex and split set tube bolts), as these elements were used extensively at this time. It was not until the 1970’s that the use of cables for ground reinforcement developed, and as such highlighted the need to extend load transfer property testing to include shear strength of cable bolts. Initially, the discarded hoisting ropes were used for ground support in metal mines, particularly in stopping wall support and then late in 1980’s cable tendons began to use in coal mines."

Jan 1, 2019

By John T. Awald

The efficiency of search for porphyry copper and molybdenum deposits can be greatly increased. A model exploration system is here presented to show how geologic literature data and field surveys can be aided by modern statistical and computer methods. Assuming that major ore deposits occur in clusters, it is possible to evaluate rapidly large areas at modest cost and with minimum investment risk. An example of the success of these methods is given. Clusters of mine density and metal production covering the State of Nevada were plotted and machine contoured. Selection of a 47,300 square-mile area on the Nevada-California border was made. Within this area, detailed analyses were performed, and a 3000 square-mile site was picked for subsequent field examination. To initiate efficiently the field work, 81 stream sediment geochemical samples were collected and analyzed for copper, zinc, and molybdenum. These data established local variance and necessary statistical controls. Following this, a total of 151 geochemical samples were used to survey the 3000 square-mile area. Computer contouring of results directed attention to specific target areas for detailed geologic analysis, property acquisition and drilling. A total of 22 copper-zinc and molybdenum anomalies were identified. Four of these were recommended for further exploration. To date, two have been acquired and drilled and preliminary ore reserve and financial analysis have been made on one. The estimated cost and time for the regional exploration phases leading to these targets were thirty man-weeks and $16,000.

Jan 1, 1973

By Juan Ares, Enrique Fernández, Alejandro Sanz, Francisco González

"INTRODUCTION Crossrail is a subsidiary company of Transport for London created for the construction of a new transverse train line 118 km long between Maidenhead and Heathrow in the West, and Shenfield and Abbey Wood in the East, including 21 km underground below London. Crossrail C305 Eastern Running Tunnels project is the biggest contract within Crossrail Project and involved boring 11.8 km of twin tunnels through London’s city center. Crossrail C305 Project interfaced with different contracts along its alignment and therefore logistics and solutions had to be developed to minimize disruptions or interferences with other contractors and the neighborhood. The paper describes this innovative approach. C305 CONTRACT APPROACH C305 contract was split into three drives, to be excavated by four EPB TBMs 7.1m diameter, as shown in Figure 1. •,Drive Y: 8.2km long between Limmo Peninsula and Farringdon Station in the city center •,Drive Z: 2.7km long between Pudding Mill Lane and Stepney Green Junction •,Drive G: 0.9km long between Limmo Peninsula and Victoria Dock Portal in the East. Crossrail C305 Project scope of works included the excavation of TBM tunnels and shafts at Limmo Peninsula and Stepney Green (including 17m span turnout caverns), along with the requirement to traverse station and shaft structures of other Crossrail contracts. Limmo Peninsula Site was a strategic element as it was the only access point on the tunnel alignment with sufficient available area at the surface for tunnelling logistics and also connected to the Lea River, tributary of the River Thames which facilitated marine operations for segment supply and muck removal. These were the reasons for operating Drive Y & Drive G TBMs from that location. Drive Z TBMs were originally planned to be launched from Stepney Green to Pudding Mill Lane, supplying the TBMs during Drive Z excavation from Limmo Peninsula site through the excavated section of Drive Y between Limmo and Stepney Green. During the early stages of the project, a value engineering proposal with a new tunneling strategy was agreed wherein the Pudding Mill Lane contractor would provide space for TBM assembly and operation in their portal, allowing for reversing Drive Z excavation and launching the two TBMs from Pudding Mill Lane. This optimization reduced some of the shaft requirements at Stepney Green which were contingent upon critical enabling works and provided program certainty and cost savings for the full Crossrail Project. It allowed for the reuse of both the Drive Z TBMs for Drive G excavation from Limmo to Victoria Dock Portal thereby saving on the procurement of two TBMs, in addition to easier logistics for both Drives Y&Z, therefore de-risking the TBM excavation process and the C305 Project program completion."

Jan 1, 2016

By Yi Luo

Longwall coal mines are frequently located in steep mountainous areas with narrow valleys. In order to protect surrounding watersheds and residential structures, support areas are left under the valleys. However, the indirect subsidence effects to the residential structures due to the potential topography effects can be a serious problem. The present study examines a longwall mine in southern West Virginia located in an area with an average slope of about 30°, or 58%, and with an overburden depth that varies from 49 to 376 m (160 to 1,235 ft). A comprehensive investigation was carried out to assess the subsidence and topography effects, as well as other ground control issues at this site. Surface and subsurface movements and deformation were predicted and their direct effects on nearby streams and structures were assessed. The potential and indirect subsidence influences of surface topography effects were assessed. The techniques and results of this investigation are presented in this paper. It shows that the direct and indirect subsidence effects on the streams and residential structures should be insignificant. The post-mining observations agreed well with this study.

Jan 1, 2010

By John C. Nixon

In 1959, The Australasian Institute of Mining and Metallurgy (Aus. I.M.M.) was asked by the Federal Government of Australia and the State Government of South Australia to join in the formation and management of a new contract research organization which was subsequently named The Australian Mineral Development Laboratories (Arndel) ? This body was formerly the Research and Development Branch of the South Australian Department of Mines which had been set up to develop the Radium Hill uranium deposit. It had then gone into contract R&D and the State felt that it would be more appropriate for the Branch to become a separate national organization. The Aus. I.M.M. decided that a professional institute could not participate directly in Arndel and, as there was no other suitable industry group to do so, it formed the. Australian Mineral Industries Research Association Limited (AMIRA). AMIRA held its first Annual General Meeting in September 1959 when the first Council was elected and the Memorandum and Articles of Association were adopted. The initial task of AMIRA was to raise guarantees of work or cash from its members to underwrite Arndel for the first five years of operation. The Federal and State Governments also provided guarantees and Arndel commenced operations in January 1960.

Jan 1, 1977

By T. M. Needham

Increasing ore hardness led to a gradual reduction of mill throughput rates. This, combined with declining head grades and low gold price, prompted a review of milling practice at Kidston. Plant trials and computer simulation of the grinding circuit indicated the potential to increase mill throughput by up to 451 by reducing SAG mill feed size. Secondary crushing and additional ball milling capacity were installed. Commissioning was carried out successfully in September/October 1992. Design, operation and problems of the expanded circuit are discussed, and recent operating results are presented.

Jan 1, 1994

By Håkan Stille, Jalaeddin Y. Rafi, Fredrik Johansson

"INTRODUCTIONIn tunneling projects, pre-grouting is performed with the purpose of establishing an impervious zone around the tunnel periphery. This is obtained by reducing the penetrability of the most conductive fractures in the rock mass. The main attention, besides economy of the project, is given to limiting the ingress of water into the tunnel to a certain amount during construction s well as operation period. Failure in pre-grouting process may, according to Bruce (2007), significantly affect the project in terms of safety, performance, cost and time. In this respect, determination of design parameters (pumping pressure, properties of the mix and stop criteria) affects these projects significantly. In current practices, depends on the geological conditions and requirements of the project these parameters differ widely. Weaver (1991) recommends selection of design parameters, specifically grout injection pressures, based on site specific factors and the conditions at each specific hole into which grout is to be injected (grout hole logging and water pressure test data). Houlsby (1990) correlated the allowable grouting pressure to the quality of the rock mass and the rock cover above the grouted fracture. In his methodology, grouting should be continued until the maximum pressure was attained. Later, Lombardi and Deere (1993) introduced the Grout Intensity Number (GIN), which limits the combination of injection pressure and injected grout volume in order to control the energy induced in the fracture i.e. avoid fracture jacking. Even though the GIN method was a step forward in understanding of the mechanism of the fracture deformation, there are ambiguities connected to this methodology, thus determination of the intensity number is challenging (see e.g., Rafi and Stille 2015)a.A main problem when no theoretical solution is practiced is that effects from the chosen injection pressure, such as possible increases of transmissivity and changes in total grouting time, remains hidden in the overall grouting process. The question is if a high or a low pressure should be used to fulfil the requirements of the projects at the lowest possible cost."

Jan 1, 2016

By Charles H. Greene

This paper will describe briefly the steps taken in the development of a Central Florida phosphate ore deposit from acquisition to mining. Further, the design and early operation of the mining and beneficiation facilities will be depicted. During the 1950's, with confidence in the continually increasing requirement for phosphate fertilizer materials essential for producing food, I'. R. Grace & Cc acquired the Hookers Prairie tract containing approximately 45 million metric tons o. (50 million short ton~ of potential phosphate rock product. In 1973, at a point when the Grace captive need for rock was being greatly enlarged by a planned doubling of its Bartow phosphate chemicals plant capacity, the decision was made to expand existing phosphate rock production by building a new mine and plant. The initial annual capacity was to be 2.3 million tons (2.5 million st); however, subsequent investigation pointed to a higher than estimated dragline operating factor 'and the forecast of annual capacity was set at 2.5 million tons (2.8 million st).

Jan 1, 1977

By Guy T. Jr. McBride

World food production is not matching the exploding increase in world-population. Since arable land is limited, ways are being sought to increase yields by turning_ to fertilizer. Phosphate, an essential fertilizer ingredient, is undergoing a period of growth unparalleled in history. The United States is at once the world's largest producer of food and of phosphate rock. Both food and fertilizer output in the United States are being enlarged to meet the demands posed by the threatening world food crisis. New phosphate deposits are being developed in Florida and North Carolina to assure the United States' continued preeminence in this vital resource. Large fertilizer complexes are also being constructed with an eye to both domestic and foreign markets. The growth of the U. S. phosphate industry has been characterized by developing technology in the processing and distribution of phosphate raw materials. The trend from low analysis to high analysis materials accompanied by a change from a large number of small fertilizer plants oriented toward the marketplace to a fewer number of large plants located at the raw material source is illustrative. These changes in technology and distribution have also been important factors in the development of new mining areas in Florida, the Western States and North Carolina.

Jan 1, 1966

By Eleanor Kentish, Nathan Bond, Edward Batty, Simon Webber, Alan Skarda

"Crossrail is Europe’s largest construction project — a new 100km rail route running through central London. A joint venture of BAM, Ferrovial and Kier (BFK) has constructed the tunnels and escalator shafts at the new Bond Street and Farringdon Stations. The recent trend in the UK industry towards sprayed secondary linings is driven by the potential for significant savings in cost and time. BFK is unique within Crossrail by constructing both sprayed and cast secondary linings. This paper presents a direct comparison between sprayed and traditional cast in situ secondary linings at Bond Street and Farringdon Crossrail Stations. An objective comparison is drawn between procurement and mobilisation periods, production rates, flexibility, tolerances and logistics in the tunnels. The technical challenges surrounding cast and sprayed secondary linings are explored, and recommendations are made of how each method could be improved for future use. INTRODUCTION It is well established that sprayed concrete offers a fast and effective method to seal the face of an excavation. In a relatively short space of time, sprayed concrete can be applied to an open face to support the short term ground loading on the tunnels during construction. Advances in sprayed concrete lining (SCL) technology — such as the use of wet mix processes, improved accelerators, fiber reinforcement, remotely controlled spraying robots, innovative surveying equipment and nozzleman competency schemes — have greatly increased the speed and safety of tunnel excavations using this technique. As a result, design engineers have become increasingly confident to use SCL primary linings as part of the permanent structural lining (Su 2014). Historically, long term ground and water pressure loads have been considered to be carried by the main structural or secondary lining, constructed using cast in situ concrete (Pickett 2014). However, the advances described above have made sprayed secondary linings a viable option, which has already been proven on the A3 Hindhead Tunnel (Arnold 2012). Sprayed concrete secondary linings offer potentially significant savings in cost and time during the construction process. The contractor does not need to procure a bespoke formwork system for each different sized tunnel — the SCL plant required is already on site for the primary lining. Each bay is sprayed with accelerated concrete, becoming self-supporting almost immediately — compared to moving and resetting the shutter, pumping concrete and waiting for it to cure. With sprayed concrete, working sequences and cross sections can easily be changed."

Jan 1, 2016

By Jerry Wang, Greg Bold, Mahmood Khwaja, Rebecca Caldon, William Simcoe

Phase III and Phase IV of the Beaver Creek Clean River Project, Albany, NY, includes microtunnel construction of 2,320 feet of 48-inch/36-inch internal diameter (ID) conveyance pipe and a 525 foot long 9.5-ft horseshoe shape roadheader excavated tunnel. Notable challenges were encountered during the construction including mixed face tunnel conditions, undocumented existing fill ground conditions that resulted in settlement during shaft construction, and unstable tunnel face conditions. This paper discusses several of the key challenges encountered during construction and selected solutions to construction sequencing and methodology to successfully complete Phase III and Phase IV of the Beaver Creek Clean River Project.

Dec 1, 2022

By J. A. L. Campbell

Peabody's Camoy mining system is a truly continuous conceptual method of underground mining of coal. The system solves the three factors which limit coal from being mined continuously. Camoy's principal features are improved productivity and increased recovery. A conservative retreat production rate of 2 1/2 times normal continuous miner room-and-pillar mining rates are projected for a 6-7' seam. Overall mine productivity will be 2 times normal, with a potential for considerably higher rates. Major incremental production increases can be achieved by partial implementation of the system. Total mine recoveries of 75% are expected. The system includes both advance and retreat mining. The retreat half of the approach encompasses many of the features of short wall mining. A central panel is prepared for retreat mining by driving entries using room-and-pillar mining to the left and right of it. The room-and-pillar mining encompasses the advance features of Camoy. In the retreat phase, the roof of the face is supported by self advancing chocks or shields. All mining is done under the chocks by a continuous miner. As the miner advances the chocks continuously move forward behind it. Thus, as in a typical short wall system, continuous roof support is attained. Ventilation is unidirectional, another characteristic of short-wall type systems. Fresh air is brought in and passed over the working personnel. It moves to the face where the continuous miner is operating, picks up the generated dust and released methane, and is exhausted away from all personnel. Exposure to respirable dust and ignition hazards due to methane build-ups are almost totally eliminated. Thus, the second limiting factor is overcome and continuous ventilation is attained. Coal mined with the continuous miner is passed to a surge car and then to a Serpentix conveyor. The Serpentix, a Peabody invention, is a flexible conveyor capable of going around corners.

Jan 1, 1976

By T. A. McAfoose

As one of the major suppliers of the chestnut Ridge energy center, Rochester and Pittsburgh Coal Company continues the search for more efficient haulage systems. This search is one that is essential in providing coal to the Keystone and Homer City power plants at the most economical cost. These two electrical generating plants located in west central Pennsylvania are part of the energy center which consists of four generating stations. Prior to the time the two stations were put on line, August, 1967 for Keystone and August, 1969 for Homer City, our company made the decision to rely on belt conveyors from the section to the surface to provide for continuous main line haulage. The proximity of these generating stations to proven reserves allow for minimal truck haulage and minemouth setups. With the addition of seven new mines, in the past ten years, revisions have been made on the original setup to interconnect the haulage of several mines to deliver the product by belt to the power plants.

Jan 1, 1979

By R. A. Matuszak

U.S. Government sponsored studies proclaim large reductions in surface mine productivity. Consulting studies place a large share of the blame on increased governmental regulatory activities and on inexperienced, improperly train people. Union rules, which allow indescriminate bidding for job openings, seem to be a major factor causing the lack of experience in spite of elaborate training programs.

Jan 1, 1982

By Richard H. Olson

Talc deposits in the Precambrian of southwestern Montana (Beaverhead and Madison Counties) are unique within the U. S. A. in that large bodies of tremolite-free talc can be open-pit mined. All known deposits are in pre-Beltian dolomite units. The origin is suspected to be metasomatic, with the siliceous component having been contributed by an intrusive Precambrian granite gneiss. Precambrian deformation was extreme and is characterized by multiple periods of tight isoclinal folding and the flowage of less competent rocks, rather than by faulting. Post- Precambrian folding has been relatively negligible; the characteristic Laramide structure is block-faulting developed along northwest-southeast trends. The talc is thought to have been formed in Precambrian time; the high-angle block-faults probably have no significance with regard to the formation of the talc, but do tend to complicate mining operations. Tremolite-free talc ore bodies with horizontal widths of more than 200 feet, vertical depths of several hundreds of feet, and strike-lengths of as much as one-half mile are known in the Ruby Range and the Gravelly Range. Where dolomite is interbedded with tremolite-free talc in the Gravelly Range, the scale of this relationship permits the use of conventional open-pit mining methods with subsequent upgrading by hand-sorting techniques. Underground mining has been used in the past, but all current Montana talc-mining operations are on the surface. The hand-sorted ore, some of which is shipped overseas, is finely ground or micronized in roller mills and fluid-energy mills. The products are distributed both nationwide and abroad.

Jan 1, 1975

By J. Castaneda, J. Schmidt

"INTRODUCTION Chino is an open-pit copper mining complex faced with intricate material routing requirements. Historically, this was challenging at the mine, in part because the shovel dig plan, haul plan, and dump plan were prepared completely separately. The mine now uses an integrated workflow for faster evaluation of schedules, which facilitates preparing balanced cutoff grade-to-equipment requirements, supports better mineral production, and improves schedule viability, while considering operational implications. Located in the state of New Mexico, Chino is one of nine Freeport-McMoRan mining operations in North America. This presentation discusses the benefits of implementing an integrated approach to tactical mine planning, and shares practical examples that were learned as Chino implemented an integrated tactical planning method. This includes improvements in completion time for preparing a schedule, minimal risk from manipulating Excel macros, data integration required to make short-term planning decisions, and better understanding of the mine plan’s effect in relation to the business’s key performance indicators. Ultimately, the integrated approach to tactical mine planning at Chino has led to production forecasts which are more achievable and reduced planning and execution variance. PROJECT OVERVIEW Chino mine is a porphyry copper deposit wholly owned by Freeport-McMoRan, the largest publicly traded copper producer in the world. Chino mine is located in Grant County, New Mexico, a short distance east of Silver City. Ore material mined from the pit today includes oxides, primary sulfides, and secondary sulfides. The mineralized material is sent to a mill, with a rated throughput of 42,000 tons per day, or to ROM leach pads with variable dumping capacities. At Chino, the short-range objective is to maximize total copper pounds sent to the mill, but no fixed cutoff grade accomplishes this for all periods. Instead, 12 different material classifications, including four sulfide classes that can feed either the mill or other destinations, and 38 cutoff bins, are aligned with the needs from operations, leaching, and the concentrator to create a schedule. Cutoffs vary from one week to another to cope with a highly intermittent ore body."

Jan 1, 2018

Lack of selectivity in mixed mineral flocculation can be attributed to one or more of the following factors: dissolved ion interference, heterocoagulation, mechanical entrapment in flocs and entrainment of fines between flocs. In a study of apatite- dolomite system, it was determined that dissolved ions do not have a significant effect on selectivity. Heterocoagulation was minimized by choosing proper process conditions and addition of a dispersant. Mechanical entrapment was proved to be insignificant and efforts were made to reduce entrainment by choosing an appropriate method of separation of flocs from fines. A new factor termed "polymer induced entrapment" which occurs due to limited affinity of the polymer to the mineral which is not flocculated is postulated to be the cause for the loss of selectivity.

Jan 1, 1986

By S. Peng, Yi Luo

Subsurface strata movements and deformations associated with underground longwall mining activities could cause certain influences to subsurface structures and water bodies. Methods have been developed for the prediction of final and dynamic subsurface movements and deformations induced by underground longwall mining operations in the eastern coal fields. Two new types of strata deformation, vertical and total strains, which could be useful in the field of subsidence research in assessing subsidence influences to the subsurface structures and water bodies, have been introduced. Using the subsurface subsidence prediction model, three types of subsidence influences to surface and subsurface hydrological systems have been identified. Attempts have been made to quantify the two types of subsidence influences that could cause water loss and could lower water levels in aquifers.

Jan 1, 2010