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By J M. Marwan, B Tang

Strain-type rockbursts, or strainbursts, are characterised by a localised violent failure. Their cause is attributed primarily to the sudden release of strain energy, which accumulates in a volume of highly stressed rock as a result of mining activities. Examples of such phenomena are crown/sill pillar bursts created in the mining process, pillar crush in room-and-pillar mining, face ejection in drift development headings at depth, and floor bursts associated with deep shaft sinking. The paper describes a simple method for the assessment of crown pillar bursts in steeply dipping ore deposits which are extracted by the overhand cut-and-fill method. The method is based on a theory previously established by the author to help assess the need for a remedial solution such as pillar destress blasting. Basically, the mining-induced energy storage rate (ESR) in the pillar is compared with the critical strain energy to come up with the so-called burst potential index (BPI).

Jan 1, 2001

By G. Bacon

The past decade has witnessed unprecedented growth in the development and implementation of solvent extraction technology in the extractive metallurgy of nickel and cobalt. Solvent extraction is proving to be a powerful tool, opening new opportunities for simpler, more cost efficient and environmentally sound metal refining processes. These advances, however, could not have been possible without the cooperative efforts between the nickel industry and the people and organizations involved with reagents, materials and equipment development and supply as well as solvent extraction research, aided by the accumulated knowledge and practical experience from the copper and uranium solvent extraction operations. This paper provides an overview of these developments and some of the challenges ahead.

Jan 1, 2002

By Marvin V. Damm, Lloyd C. Venburg, Dan Sokol

Analytical and computer models are used to evaluate information obtained from existing data and investigation programs so mine water control systems can be designed and developed. These models allow the geohydrologist to predict the amount of groundwater inflow and the impact of dewatering and stream diversion on the hydrologic regime, and to determine the schedule and equipment needed for mine dewatering. This article describes uses of the model and the essential components necessary to construct an effective and practical one. Hydrologic models are constructed to determine the extent that mining activities will affect the ground water and surface water hydrologic regime. These models range from basic analytical, mathematical models to the more sophisticated finite difference and finite element groundwater models. Many factors determine the degree of sophistication, including the mining stage, the complexity of the hydrologic regime, the mining process, and regulatory requirements. Model Uses The geohydrologist and engineer construct models so the entire ground and surface water handling and supply system can be integrated and optimized. These models can provide the following data: • Information for water balance studies-the entire hydrologic regime for the area, including precipitation, transpiration, evaporation, infiltration, runoff, and the effect of geologic features. • Data on seepage rates during mining. • Information to design the depressurization and dewatering system, including water well spacing, location of sumping systems, need for grout curtains, and possible horizontal drain and underdrain locations. • Data needed to schedule dewatering and mining operations. • Prediction of initial and long-term impacts of mining and dewatering, including local and areal drawdowns, effects on existing wells, and modifications to the surface-subsurface hydrologic regime. Potentiometric surface maps and hydrographs can be prepared from these data. • Prediction of the effect of discharge from the water control system on the surface hydrology and data input to design systems for water discharge, storage, recharge, or reinjection. The results of a computer study that illustrates the effect of dewatering and reinjection into an aquifer to confine the cone of depression are shown on the accompanying figure. • Information to forecast potentiometric surface recovery after mining ceases. The accompanying figure shows the pumping and reinjection rates in a program that is adequate to dewater a mine and permit the recovery of potentiometric levels to approximate premining levels after mining ceases. • Documentation and design information for monitoring systems to be installed during all mining phases. • Water quality predictions and geochemical changes, including the possibility of brackish or saline water intrusion because of extensive dewatering or depressurization operations. • Documentation and data for acquiring permits from regulatory agencies. Model Input Program For any model to be effective, detailed hydrologic and geologic data must be gathered from a review of existing information and from an investigative program. These data should cover entire model limits. Data updating, revising, and refining should occur as new information is received from the investigation and monitoring programs, and from the mining operation as it progresses through the pre-mining, mining, post-mining, and reclamation

Jan 8, 1982

LIST OF THE MEETINGS OF THE INSTITUTE AND THEIR LOCALITIES FROM ITS ORGANIZATION TO OCTOBER, 1904 Transactions Number Place Date Vol Page 1 Wilkes-Barre, Pa May, ?71 1 3 2 Bethlehem, Pa August, ?71 1 10 3 Troy, N Y November, ?71 1 13 4 Philadelphia, Pa February, ?72 1 17 5 New York, N Y May, ?72 1 20 6 Pittsburg, Pa October, ?72 1 25 7 Boston, Mass February, ?73 1 28 8 Philadelphia, Pa May, ?73 2 3 9 Easton, Pa October, ?73 2 7 10 New York, N Y February, ?74 211 11 St Louis, Mo May, ?74 3 3 12 Hazleton, Pa October, ?74 3 8 13 New Haven, Conn February, ?75 3 15 14 Dover, N J May, ?75 4 3 15 Cleveland, 0 October, ?75 4 9 16 Washington, D C February, ?76 4 18 17 Philadelphia, Pat June, ?76, 5 3 18 Philadelphia, Pa October, ?76 5 9 19 New York, N Y February, ?77 5 27 20 Wilkes-Barre, Pa May, ?77 6 3 21 Amenia, N Y October, ?77 6 10 22 Philadelphia, Pa. May, ?78 6 18 23 Chattanooga, Tenn May ?78 7 3 24 Lake George, N.Y. Oct. ?78 7 25 Baltimore, Md. Feb. ?79 7 26 Pittsburgh Pa, May ?79 8 28 Montreal, Canada Sept, ?79 8

Jan 1, 1923

By J. Mitchell Linne

The principal mineral commodity in the Orleans Mountain RARE II area (No. 35019) is gold. Gravel deposits along the Salmon River contain placer gold. Lode gold with associated silver is contained in quartz veins. Many placer mining claims have been located within the study area in the Salmon River district. Four placer patents totalling 230 acres were issued for claims on the Salmon River between Lewis Creek and Forks of Salmon. On this same reach of river, adjoining and overlapping the study area boundary, approximately 3.3 million cu yd (2.5 million cu m) of gold bearing gravel with values ranging from $0.51 to nearly $5 per cu yd (50.66 to $6.50 per cu m) (gold valued at $400 per troy oz), are contained in three placers, the Bloomer, Pot Luck, and Horn (table 1). Within the study area boundary there are approximately 950,000 cu yd (726,000 cu m) of gold bearing gravel in these three placers. These three mines yielded nearly 12,000 oz (373,000 g) of gold and more than 300 oz (25,000 g) of silver between 1872 and 1913.

Jan 1, 1982

A Mechanistic Model of Batch Grinding in Ball Mills

Sep 13, 2010

By L. M. English, Y. J. Wang

When plotted as head vs. volume, fan curves start high and decrease in head with increasing volume while mine head curves start low and rise with increasing volume. Their intersection is the system operating point. But wait a minute: Isn't head loss a negative number, a debit? And isn't fan head an energy addition, a credit? This, as every ventilation instructor knows, is often a stumbling block to student or audience comprehension. It is possible to use the intuitively correct curves - pressure losses as negative values and energy additions as positive values-and still obtain the correct operating point: adding the two curves produces a third curve that intersects the x-axis at the operating point, the point at which the fan energy input exactly matches air circulation energy loss. Using this technique also makes it easier to account for outside influences on the system, such as natural ventilating pressure; with the standard approach it is quite easy to add or subtract such influences to the wrong curve. This approach can be extended to the graphical solution of any series/parallel circuit or ventilation network. The results are the same, and the approach is logically consistent and less confusing.

Feb 24, 1997

The transgressive sedimentary sequence of the Noumea Basin contains rhyolitic lavas and less voluminous mafic and intermediate volcanics of shoshonitic affinities which erupted simultaneously during the late Cretaceous. The shoshonitic volcanism shows a trend froIn early mafic to younger evolved intermediate lithologies. The rhyolites are consistently calcalkaline. There is no evidence of mixing of the two magma types. The shoshonitic volcanism is the result of a short-lived subduction event related to spreading in the New Caledonia Basin and involved reactivation of an earlier esozoic subduction zone.

Jan 1, 1995

By John Ward Smith

Dawsonite-bearing oil shale of Colorado's Green River formation offers a unique and vast (more than 5.9 Gt of A120 j) resource of easily extractable alumina. The processing methods required by the thermal reactions of dawsonite and its oil-shale carrier also require production of shale oil, soda ash, and nahcolite as marketable coproducts. These production methods are presented. The alumina production process is contrasted with the Bayer process to describe technical advantages of extraction of alumina from oil shale which may offset the problems associated with processing a relatively lean ore. While alumina production from oil shale requires development of new technology, the technical problems appear solvable. Only the political problems arising from the now onerous and completely unnecessary federal oil-shale withdrawal appear less solvable.

Jan 1, 1982

By M. Martins

This work presents and discusses the influence of the surface tension (gLV) of methanol/water mixtures on the flotation response of apatite versus gangue minerals conditioned with flotation reagents (75 g/t cornstarch and 100 g/t Berol 867) at pH 10.6. Berol 867 is a collector composed of sodium alkyl sarcosinate plus nonionic surfactant. The highest Schulz efficiency of separation (recovery of apatite minus recovery of gangue) was achieved at ?51.0 mN/m. The critical surface tension of wettability (gC) of apatite was found to occur at 34.7 mN/m when determined by means of gamma flotation experiments, and it was 33.9 mN/m when determined by Zisman?s approach.

Jan 1, 2009

By F M. Weir, M Fowler

A discrete fracture network (DFN) approach involves numerical modelling that explicitly represents how defects may be spatially distributed through a rock mass. A DFN is a 3D realisation of the ‘smaller scale’, non-deterministic defects; it is not an attempt to model larger, deterministic structures that should be identified as part of an engineering geology model. The approach utilises structural data in stochastic analyses to give a range of possible models that provides a tool for visualisation and analysis of a rock mass and indicates the potential large-scale slope or tunnel performance and stability.Stochastic fracture modelling for rock mass characterisation has significantly advanced over the past 25 years. With recent improvements to field data collection and computational power, it has become recognised internationally as a valuable tool for modelling some geomechanical problems encountered when designing excavations in fractured rock masses.This paper provides an introduction to the DFN approach, particularly the necessary input parameters and derivation of these from typical structural data sources, such as boreholes or scan line mapping. Of particular importance for engineering applications is validation of the simulated fracture network and techniques for doing so are discussed here.CITATION:Weir, F M and Fowler, M, 2014. An introduction to discrete fracture network modelling and its geotechnical applications, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 435–444 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By G. E. Agar

In the April issue of Mining Engineering there is a technical note "New size laboratory ball mill for Bond Work Index determination" written by M. Nematollahi which is very confusing. My recollection is that a description of an experimental procedure should be such that someone skilled in the art should be able to reproduce the results. Applying this test to this particular article would according to me cause a failure to be registered. There are apparently three batch laboratory test procedures referred to in the article. One of these is the traditional Bond test with all its limitations such as dry grinding followed by exclusively dry screening, two attributes which fail to simulate conventional industrial grinding. There is a second procedure (NSBM) which the author is advocating as an improvement of the Bond procedure but from the description I doubt that anyone would be able to repeat the procedure. For instance, is the grinding to be done wet or dry, if wet at what pulp density, and how is the screening to be done, wet or dry or a combination?

Jan 1, 1995

By L. G. Marshall

This report is one of a series published by the Federal Bureau of Mines, describing mining methods and performance at individual mining operations throughout the United States. The objective of these papers is to promote development and conservation of our mineral resources by disseminating reliable technological information on mining methods, practices, and performance. Limestone deposits in Iowa are extensive and reserves are large. Most of the past production came from the eastern third of the state, although over half of the counties in the state have produced, or are now producing limestone. The stone is used as aggregate, road metal, agricultural lime, riprap, fluxing stone, railroad ballast, and in the manufacture of cement and lime.

Jan 1, 1962

Minerals Industry - 5 Year Outlook AusIMM sponsored project Positioning the Minerals industry for the 21st Century Does this seem right for New Zealand?  To ascertain the industry's perceptions of issues and capacity to address them: Industry context and issues Capabilities of professional staff Access to professional staff Balancing supply and demand Industry must do it. Cannot wait for others.   Some observations... Negative image - constrains capacity to influence community and government Major repositioning of professional staff competencies required Existing organisational arrangements and capabilities are under pressure to change Difficult to access professional staff of required capability Facing significant external challenges - with real concern about capacity to address them Prevailing culture not suited to needs of the future High level felt need for change The industry has a choiceà We can define where we want to be and act decisively Or We can respond to the future as it unfolds.

Jan 1, 2000

By P. J. Rider

Diamond Value Management?s objective is to achieve $/ton revenue improvement across De Beers group mines. The respective %improvement contributions are measured against targets set by each of the operations. Degree of target achievement is measured via a maturity model at each operation. DVM comprises seven elements. It spans several value chain facets and various collaborative projects are conducted under its umbrella. New technologies in De Beers are also evaluated from a DVM perspective.

Jan 1, 2003

By Scott W. Hazen

COMPREHENSIVE summary is presented of results of several years of research at the Bureau of Mines Mining Research Center at Denver on adapting and applying techniques of statistical analysis in mine and mineral-deposit sampling and in computing grade and tonnage of ore for a mineral deposit. In addition to elementary statistical theory the material presented in the bulletin includes: (1) Certain special statistical techniques that have been found useful in mining applications; (2) problems, implications, and limitations that may be encountered in applying these techniques in mine sampling and evaluation; and (3) numerous examples to demonstrate application of the theory and techniques.

Jan 1, 1967

By Glen Frank, David R. Chapman

Determining the number of boulders and cobbles that will be encountered in the tunnel envelope is one of the most difficult problems confronting the geotechnical engineer in the design of tunnels in glacial terrain. This issue is very important to the contractor, both in determining what methods will be used to construct the facilities and the advance rate that can be achieved for the chosen construction methods. The cost of constructing tunnels by pressurized face tunneling techniques is very sensitive to accurate characterization of the very coarse fraction (large cobble and boulder sized clasts), and no standard method is current available for characterizing boulders and cobbles. Careful use of large diameter borings and the sampling and analytical techniques outlined in this paper can provide a means to answer this difficult question. By performing large diameter borings and carefully recording and sampling the cobbles and boulders encountered, an estimate for the amount of these materials present in the formations sampled can be provided. Using this method allows the designer to communicate the expected geologic conditions to the prospective bidders in a manner that is both definitive and defensible. This paper describes the method as it was used in conjunction with the design of a large diameter sewer tunnel in the Columbus, Ohio area.

Jan 1, 2005

By PW Meisel

An hydraulic-powered reel system to minimize peak tension transients in shuttle car trailing cables has been theoretically designed and analyzed using a computer. A single spring-loaded take-up sheave stores or gives up cable to maintain tension within specified limits. Controls have been incorporated to shut down the vehicle before all cable is removed from the reel and to de-energize the cable in the event of a reel/cable jam. Full-scale hardware configuration drawings sufficient for manufacture of a test system have been completed.

Jan 1, 1983

By Manuel Rapiman, Ricardo Sepulveda

The feasibility study of Escondida Norte (ENorte), recommended a slope angle design for the Final Pit. But, according to the experience obtained with the slope adjacent to the West wall of ENorte, in which Compañia Minera Zaldívar (CMZ) gained in its phase 4, a slope of similar geotechnical characteristics will be exposed in the West Wall of Phase 1 (Premine) and of the Final Pit, with an interramp angle 53º and with very good stability results. In this regard, Minera Escondida Ltd. (MEL) performed a study of the slope angles for the phases mentioned and according to this delivered the results of this evaluation, the recommendations and/or the necessary conclusions in the design to ensure that the slopes are stable enough and may enable safe operational management of them.

Jan 1, 2006

By Neil R. Burns, Michael Doggett

Abstract - The Nanisivik mine offers a unique opportunity to examine the economics of a mining scenario from its original feasibility study through to closure. In the early 1970s, the Strathcona Sound project (exploration around the Nanisivik mine) had advanced to the point where a significant mineralized body had been defined and a feasibility study was initiated. The study supported development of the Nanisivik mine, with government investment in regional infrastructure, and the mine was constructed and operated for 26 years. Many elements of the feasibility study were difficult to estimate because the project was unique in its high Arctic setting. As a result, many differences were found when comparing the actual mining data to the feasibility study. The majority of these differences were the result of an actual mine life of 26 years instead of the planned 12.5 years. Most of the mining costs were higher than estimated and production occurred at a much higher extraction rate than planned. On a constant dollar basis, the metal prices were, on average, below the feasibility estimates. For the most part, these differences balanced out, with the actual mining being only slightly more profitable than anticipated in the feasibility study.

Jan 1, 2004