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By Christopher Mark

"Many problems in rock mechanics are limited by our imperfect knowledge of the material properties and failure mechanics of rock masses. Mining problems are somewhat unique, however, in that plenty of real world experience is generally available and can be turned into valuable experimental data. Every pillar that is developed, or stope that is mined, represents a full-scale test of a rock mechanics design. By harvesting these data, and then using the appropriate statistical techniques to interpret them, mining engineers have developed powerful design techniques that are widely used around the world. Successful empirical methods are readily accepted because they are simple, transparent, practical, and firmly tethered to reality.The author has been intimately associated with empirical design for his entire career. But where his past papers have described the application of individual techniques to specific problems, the focus of this paper is the process used to develop a successful empirical method. A six-stage process is described:1. Identification of the problem, and of the end users of the final product2. Development of a conceptual rock mechanics model, and identification of the key parameters in that model3. Identification of measures for each of the key parameters, and the development of new measures (such as rating scales) where necessary4. Data sources and data collection5. Statistical analysis6. Packaging of the final productEach of these stages has its own potential rewards and pitfalls, which will be illustrated by incidents from the author’s own experience. The ultimate goal of this paper is to provide a new and deeper appreciation for empirical techniques, as well as some guidelines and opportunities for future developers."

Jan 1, 2015

By L. W. T. Weitzel

"This paper reviews the Falconbridge- SMRQ’s Raglan project in northern Quebec and the process that was used in developing its current long-term mine plan. Challenges were many and not only limited to the longevity of the project, numerous ore deposits (both underground and open pit), and a 40 km property strike length. As a result of its remote northern location, other factors such as progressive reclamation, leachable mine waste, water treatment, and waste management were also part of the plan. A combination of modern planning tools were used to formulate the plan including DataMine, Mine 2-4D, AutoMod Simulation, and an Excel-based financial spreadsheet to bring the total plan together. The focus of the paper is to show the complexity of modern mine planning and associated economic modelling of mine processes. IntroductionThe Raglan project is located 1660 km directly north of Quebec at the northern tip of the Quebec Peninsula in Nunavik. The main property is 40 km in length stretching from the Donaldson airport area at the eastern edge of the property to East Lake at the western edge. The Deception Bay port is 90 km north of the main complex/mill situated at Katinniq which lies approximately in the middle of the property (Fig. 1). The mine processes 1 000 000 tpy of ore from both open pit and underground sources. The mill is forecasted this year to produce more than 150 000 t of concentrate grading more than 18% nickel. All personnel and critical cargo are transported to the site via a company-leased 737 jet from Rouyn-Noranda where the main administration office is located. The majority of cargo is shipped to the site via Deception Bay from Quebec and on the return trip, nickel concentrate is shipped back. From Quebec, the nickel concentrate is sent by rail to the Falconbridge smelter in Sudbury and on the reverse rail haul, nickel matte from the smelter is sent to Norway via Quebec."

Jan 1, 2003

By S. H. Badenhorst

Zacharias Lewala discovered a diamond at Grasplatz, near Lüderitz in April 1908. While this stone may not have been the first diamond to be found in this barren, inhospitable area, it most certainly was the stone that set off a chain reaction ultimately leading to the creation of Namdeb as we know it today. [ ]

Jan 1, 2003

By Jamal Rostami, Ataollah Rahbar

"Uma Oya Multipurpose Development Project is under construction in Sri Lanka. This project involves 2 Rolled Concrete Core (RCC) Dams connected through a tunnel currently under construction by Drill and Blast method. The water is transferred from first diversion dam to the 2nd regulatory dam and from which, it will be transferred through a 14 km headrace tunnel to the top of a 650 m deep drop shaft that feeds the high pressure water to an underground powerhouse and turbine chamber for generation of 120 MW of electricity. The Headrace and Tailrace tunnels are being excavated by two 4.4 m diameter double shield TBMs. The headrace tunnel has already passed 5km milestone and is mined in hard rock, while the tailrace tunnel has been completed in rather weak and fractured ground. This paper will review the history of the project along with the geology of the site. The operation of TBM in headrace tunnel will be discussed in more detail, focusing on the challenges of excavating through very strong and abrasive quartzite and gneiss on this site, as well as reaches of tunnel in high inflow of water reaching 400 L/Sec. INTRODUCTION This paper aims to introduce the Uma Oya Multipurpose Development Project (UOMDP) as a hydro mechanical project in Sri Lanka, targeted generating hydro-electric power, transferring water for irrigation purposes and controlling seasonal devastating flood. This project lies in the south-eastern part of the central highland region of Sri Lanka (Figure 1). The main part of the project is located in the south-western part of the Badulla district in the province of Uva. The south-eastern end of the project site is in the central west of the Moneragala district (province of Uva). Bandarawela is the largest urban setting within the project area, located halfway between the upstream and the downstream ends of the planned hydropower plant and combination of dams, tunnels, and downstream facilities. The Multi-Purpose Project Of Uma Oya is planned to convey water from Uma Oya to Kirindi Oya Basin for hydroelectric energy generation includes Puhulpola RCC Dam on the Uma Oya river, Dyraaba RCC Dam on the Mahatotilla Oya river, a conveyance tunnel from Uma Oya to Mahatotilla Oya (L=3750m), a long feeder tunnel from Mahatotilla Oya to Kirindi Oya. The feeder (power) tunnel Lot consists of a headrace tunnel (L=15554m), the surge shaft (L=200m) and tank on the upstream of the vertical shaft, a vertical shaft with steel lining (L=650m), an underground powerhouse and a tailrace tunnel (L=3650m)."

Jan 1, 2016

A Study on Main and Interaction Effects of Operating Variables of Column Flotation

Sep 13, 2010

By David Bigby

In the UK, it is becoming increasingly necessary to open new longwall mining areas above old, abandoned workings. In such cases, strategic and gate roadways must often be driven and maintained across highly stressed areas and pre-existing and sometimes only recently formed subsidence troughs. Ground control at the edges of the subsidence trough can be particularly problematic, with complex combinations of stress and rock conditions being encountered depending upon the precise position in relation to underlying pillar edges. For economic recovery of these reserves, it is essential that rockbolt support is used wherever possible. It is therefore very important to the industry to develop its understanding of ground conditions and support requirements in these areas. This paper describes; ? the historical background to these problems and a series of documented UK case studies from the last 20 years. ? the experiences at UK Coal?s Riccall colliery, where a number of longwall panels were worked at a depth of around 800m, some 65m above previously worked longwalls. Actual experience is compared with pre-mining expectations and model predictions. ? design considerations and experience to date at UK Coal?s Welbeck and Thoresby collieries, which are embarking upon a series of longwalls in the Deep Soft seam, 30-40m above previously worked longwalls. The paper outlines numerical modelling techniques used to optimise such mine layouts within the complex geological and geometric constraints of a mature coalfield. These involve combinations of 2D and 3D finite difference and 3D boundary element models. It also discuss new modelling approaches which will be investigated in forthcoming EU funded research.

Jan 1, 2007

By Matthew Janes

Quality control procedures are increasingly important with today's higher capacity foundations and complex loading conditions. The need for a mobile, repeatable, nondestructive and economical load test method led to the development of an entirely new approach. The system described involves using solid propellant fuels to accelerate a reaction mass off the test pile. The force required to accelerate the reaction mass upward acts equally downward on the pile. Very high forces may be applied to the pile in a controlled, linearly increasing manner. The duration of the applied load is approximately 100 milliseconds. This rate of loading is slow enough to allow the pile and soil to react together as a composite rigid body. Pile/soil accelerations and velocities are low, typically 1 g and 1 m/s respectively. The effects combine to produce pile and soil response no longer dominated by the transfer of force via stress pulse (as with impact). Instead the pile force increases throughout the length of the pile, with pile top and toe stresses building in unison with time. This emulates the stress condition during static pile loading. Finally, state of the art instrumentation systems are used to obtain test data. Displacement is monitored directly using a laser datum and integrated receiver located at the centre axis of the pile. Force is also monitored directly using a calibrated load cell. Data is acquired and digitized using a 386 PC with user friendly software capable of producing load deflection curves and time histories in the field seconds after testing.

Jan 1, 1990

This paper gives a description of the methods of mining employed at North Broken Hill Limited, Broken Hill, N.S.W.GEOLOGICAL NOTESThe main Broken Hill lode occurs as a replacement of tightly folded pre-Cambrian sediments. Replacement has followed certain stratigraphical horizons and the main bulk of the ore is found where these have been packed into the noses of anticlinal and synclinal folds.Throughout the mine the ore-bearing folds pitch north fairly consistently at 45 degrees, as a result of which two favourable horizons in the same fold appear in plan as separate orebodies and these are referred to as the "Southern Orebody" and the "Northern Orebody" respectively.The general dip of the orebodies to the west is about 60 degrees. A typical sill is shown in the plan of the 1,400-ft level (Fig. 1).Both the hanging wall and footwall rocks throughout the mine are weak and, as a result, it is necessary that the hanging wall must be well supported after ore extraction, to prevent subsidence. The weakness in the footwall is confined to a narrow zone, approximately 60 feet in width. This weaknes.q is a source of trouble in the development headings which pass through it, It is sufficiently crushed to transmit weight from the overlying wall to the gangways below.Another feature causing ground instability is the presence of many faults. Although their effect on the shape and character of the orebody is relatively small their...

Jan 1, 1940

What is a nugget effect? In the early development of geostatistics, the term ?nugget effect? was coined for the apparent discontinuity at the beginning of many semivariogram graphs. This name was chosen to reflect the large differences found between neighbouring samples in ?nuggety? mineralizations such as Wits gold reefs. Geostatistical theory assumes that the difference between a sampled value and a potential repeat sample at the same location is actually zero. Included in this ?nugget effect? would be true variation between contiguous samples due to the nature of the mineralization, micro-fracturing, nugget or crystal size, and so on. Also included in the nugget effect would be any ?random? sampling variation which might occur due to the method in which the sample was taken, the adequacy of the sample size, the assaying process, etc. Arguments were put forward that ?sampling errors? actually exist at zero distance. Some geostatistical schools actually maintain that the ?nugget effect? is all sampling error. This would imply that ?perfect? sampling would eliminate the nugget effect entirely. There is now a dichotomy both in the geostatistical world and in the software packages provided for geostatistical analyses. It may seem academic to argue over whether the semivariogram model should take a value of zero, a value equal to the nugget effect, or a partial value at distance zero. However, the decision can have a profound effect on both the estimated resource and in our confidence on that resource. Whereas most geostatistical texts define the semivariogram model as taking the value of zero at zero distance, others imply that the full nugget effect should be used at zero distance. For example: ?The nugget effect refers to the nonzero intercept of the variogram and is an overall estimate of error caused by measurement inaccuracy and environmental variability occurring at fine enough scales to be unresolved by the sampling interval3 ?Christensen4 has shown that the ?nugget effect?, or non-zero variance at the origin of the sernivariogram, can be reproduced by a measurement error model ?The nugget effect is considered random noise and may represent short-scale variability, measurement error, sample rate, etc.5. In many training texts and Web courses, the definition of the semivariogram is ambiguous as the formulae for semivariogram models is not actually specified at zero distance6,7,8.

Jan 1, 2010

By E. D. Attanasi, J. H. DeYoung

Mineral exploration activity in the US suffered through another depressed year in 1984. And continued strength in precious metals (and possibly industrial minerals) exploration failed to make up for declines in other minerals. 1984 offered little solace for the explorationist. But some new data on mineral exploration provided better statistics for analysts of US mineral exploration trends. The Society of Economic Geologists (SEG) published data from its survey of 1980,1981, and 1982 exploration by US and Canadian companies - 96 companies responded (Barber and Muessig, 1984). In addition, a Mining Engineering (April 1984 p. 345) article by Emerson and Ivosevic presented their data on annual exploration expenditures in the US for gold and for all minerals from 1961 through 1983. A review of 1984 domestic exploration and development activities reported in several industry journals indicates that almost 90% of those projects were directed at gold and silver deposits. Statistics on 1984 exploration expenditures are not available. But some industry observers believe that precious metals accounted for an even larger share of industry's exploration budget in 1984 than in 1983. According to the data of Emerson and Ivosevic (ME, April 1984, p. 349), gold exploration expendi-

Jan 5, 1985

Comminution is a vital part of minerals extraction, and therefore of the South African economy. The high cost and throughput-limiting nature of comminution forms a strong motivation for research directed at improving the efficiency of the process. Building on a ten year background of fundamental charge motion research, a new formal UCT flotation and communication group has been formed. The group is also moving strongly into the field of milling circuit modelling and simulation, based on close links formed with the Julius Kruttschnitt Mineral Research Centre (JKMRC) of Australia, and an international collaborative research programme.

Jan 1, 1998

By Deon van Tonder, Chuck Edwards

"Solvent extraction is used in many acid leach uranium circuits to upgrade and purify the uranium bearing solution prior to final product precipitation. A number of strip options are available to recover the uranium from the loaded organic. This paper compares some of these options on the basis of typical capital and operating costs for both the solvent extraction circuit and downstream uranium processing, and also considers other related issues. The aim is to provide an objective comparative assessment of these options that could be used as a qualitative guide in process selection or improvement.INTRODUCTIONIn the 1950s the uranium industry was the first industry to adopt solvent extraction (SX). Since then, the flow sheets have advanced. Notable was the introduction of tertiary amine extractants by General Mills during the late 1950s and 1960s (Mackenzie, 1997; Mackenzie, 2005), which is still today considered ‘state of the art’ technology. Initially solvent extraction was done in combination with ion-exchange, such as in the Eluex flow sheet, followed later by the adoption of direct solvent extraction from pregnant leach solution (PLS). From a strip-precipitation perspective ammonia strip followed by ammonium diuranate precipitation was widely adopted as the norm in the uranium industry. More recently alternative strip systems have been receiving increasing attention due to the environmental, health and safety issues associated with ammonia and the resulting calcined uranium oxide product. This paper explores some of these alternative options in comparison with the ammonia route.It is important to acknowledge that each operation is unique, and therefore the information and philosophy outlined in this paper serve to provide a general guide that can be potentially applied and adapted to any site or project."

Jan 1, 2013

By Betty L. Gibbs

Geologically simple deposits can be modeled quickly and easily with inexpensive gridding and mapping software. Hundreds of mines around the world use RockWorks99 and Surfer 7 for generating contour maps, producing log plots and cross sections, and performing other useful geological calculations. These programs are used by many mining operations as their only modeling and graphical software or they are used in conjunction with larger systems. The investment in learning time is low and the programs produce reasonable quality results with standard computing equipment. RockWorks99 and Surfer 7 provide a good level of capability while maintaining high quality technical integrity. Both programs are used for many applications in mining, oil and gas, environmental and other fields that require analysis of spatial data.

Jan 1, 2000

By S. H. Ash

THE BARRIER-PILLAR SYSTEM in the Lackawanna Basin consists of 93 barrier pillars between Archbald and Taylor, Pa. These pillars affect 48 mines, have a total length of 87 miles, and confine 21 underground pools, which contain more than 10 billion gallons of water. From an investigation of size, position, and condition of the barrier pillars, it is apparent that those concerned are uncertain, not only as to the method by which the sizes of the barrier pillars were determined but also as to the stability of those that may be expected to act as dams. Where a barrier pillar must act as a dam, its failure may result in loss of life, the mine, or both; it would be far better had it not existed and thereby given a false sense of security.

Jan 1, 1952

By Stephen C. Tadolini, Raymond A. Mazzoni

The International Ground Control Conference in Mining has always provided an open forum for the publication, presentation, discussion, and often heated debate on roof bolting systems mostly with attention to how, when, and why they work. During the last 24 Conferences at least 170 papers have been presented by International Experts on these “simple” devices that range in length from 30-inches to 20 ft and from 5/8 to 2 inches in diameter. Roof bolts are primarily mechanically anchored, glued, cemented, or driven. Bolts are placed vertically, angled, or tied together with special fixtures (trusses and slings). They have been termed active, passive, stick-slip, and several other descriptive acronyms or mining slang expressions. This retrospective paper will present the changes in bolt types and usage, point out some of the biggest myths and hail the most significant advances (according to the authors’ opinions of course).

By Nicholas G. Theofilos

The only mining activity in Belize during 1976 involved the production of construction aggregates, which were used domestically. A comprehensive ordinance regulating mineral prospecting and mining was proposed during the year. Under the ordinance, which would supersede all grants and titles, ownership and control of all minerals except petroleum would be vested in the Government. Exxon Corp. entered into an agreement with three oil companies to achieve a majority interest in nine oil prospecting leases covering 1 million acres, mostly offshore Belize. The agreement was with Weatherford International Inc. which had 30% interest in the leases, Ajax Petroleum Co. with 40% interest, and Canadian Superior Oil Ltd, with 24% interest. A new entity, Esso Ventures Inc., was established to be responsible for conducting extensive geophysical operations and drilling an exploratory well offshore Belize.

Jan 1, 1980

By N. Behnood

"This paper describes how material selection, quality assurance, and failure investigation play important roles in the efficiency and safety of mining and metallurgical operations.INTRODUCTION Material selection, quality assurance, and failure investigation are all complementary elements of materials engineering in the application of materials technology for failure prevention. Based on commodity price increase of 300% between 2002 to 2013 [1] and increased cost ofcapital projects and operation, equipment failure, which in some cases causes complete shutdown of the operation, becomes a vital importance in mining and metallurgical plants. The following sections present a number of examples from many failure cases experienced by the author during his three decades of work as a materials engineer in the mining industry."

Jan 1, 2015

By G. W. Luxbacher

This volume describes the use of the Penn State Mine Ventilation Simulator (PSU/MVS) to model existing mine ventilation systems and, in addition, to evaluate the effect of system modifications. Ventilation survey methods designed to insure computer input data of sufficient accuracy for simulation purposes are covered in comprehensive detail, including quantity and pressure measurement and fan performance testing. The development of input data from ventilation survey results is discussed and illustrated by the use of an actual field survey. Two programs, written in FORTRAN IV with WATFIV, are presented to calculate airway head losses from altimeter pressure measurements. An existing coal mine ventilation system is analyzed and modifications to the system are simulated and evaluated. In addition the application of the PSU/MVS to non-coal mines is briefly discussed. An extensive bibliography on ventilation surveying and simulation is included.

Jan 1, 1977

By A. C. Fieldner

"Decline of the Beehive Coke OvenTwenty years ago a favorite theme of the crusader for fuel conservation was the enormous waste of valuable by-products incurred in the manufacture of blast-furnace coke in beehive ovens. Indeed, there was good reason for arousing the national conscience to this needless' loss of an irreplaceable mineral resource. In 1910, 83 per cent of the coke production was made in beehive ovens, from which surplus gas, tar, light oil, and ammonia, aggregating in value (at 1910 prices) 40 million dollars annually, were discharged into the atmosphere.In 1929, proportions were reversed and 90 per cent of the production was made in by-product ovens. The average value of by-products obtained in the production of 1 ton of coke in 1929 was $3.60, as compared with $1.16 in 1910, although the value of a ton of coke had increased only from $3.47 to $4.80. As shown in Figure 1,1 the production of by-product coke progressed rather slowly until 1915. War needs suddenly expanded the demand for coke and the by-products benzol and toluol for the manufacture of explosives. Except during the depression of 1921, this accelerating rate of production was maintained up to 1929, largely at the expense of beehive plants. The 1929 production of 60 million tons of coke will probably remain a record-breaking figure for several years. The developments which are now in progress in long-distance transmission of rural gas and in the utilization of volatile petroleum products and refinery gases for augmenting, city gas supplies may retard an other- wise accelerating demand for coke and coke-oven gas for domestic and industrial heating, Trends in Value of By-ProductsThe increasing value of by-products in comparison to the value of coke is shown in Figure 2. In 1913, the average value of by-product coke was $3.38, the value of the by-products per ton of coke was $1.41, and the cost of coal per ton of coke was $3,27, In 1929 not shown in figure) the value of the coke had risen to $4.80 per ton, the value of the by-products to $3.60, and the cost of coal per ton of coke to $5.07. The by-product values in were 155 per cent higher than in 1913, although the coke value had increased only 25 per And the cost of the coal 55 per cent. Actually the increase or the total value of coke plus by-products in this period was very little more than the increase in the coat of the coal, being 55per cent for coal and 60 per cent for coke plus by-products."

Mar 1, 1931

By S. H. Lorain

This paper briefly describes the principal known commercial and near commercial deposits of gold-bearing gravel end the principal placer mining operations of Idaho County, Idaho. It is one of a series of similar papers on western mining districts. The data used in writing this paper were gathered during the summer of 1937. Information concerning gold-bearing gravels was obtained from prospectors and operators, while operators supplied most of the data on mining operations. No attempt was made actually to test the gravels. The principal object of the examination was to indicate placer areas worthy of further investigation by prospective operators.

Jan 1, 1938