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It is shown that, when a flat-bottomed indentor is pressed into the surface of a strong rock, the normal force necessary to cause failure of the rock is reduced substantially if a shear force is applied to the indentor. A mathematical analysis is described, which shows that higher stresses are induced in an elastic material close to the free surface of the material ahead of a punch when a shear force together with a normal force is applied to the punch. Therefore, failure of the material would occur with lower forces applied to the punch. Stress trajectories show that fractures develop in the rock along lines of maximum principal stresses.

Jan 1, 1978

By R. L. Blackwood

The solid inclusion cell for absolute in situ stress measurement has been found to give reliable results in coal. The cell is described briefly, along with the methods of installing, overcoring and taking readings in underground coal mines. The validity of the cell performance is demonstrated by reference to the stress-relief curves obtained during overcoring and a three-dimensional B.I.E.M. analysis of the installation to test for stress anomalies deriving from the geometry of the overcoring groove-borehole-cell arrangement. Case studies of two stress measurement projects using the cell are presented for coal mines in New South Wales, Australia.

Jan 1, 1982

RAYMOND M. Howe (author's reply to discussion*).-Dr. Unger states that magnesite will hardly supersede dolomite in fettling after a heat; that it is hard to believe a slag composed of oxide of iron containing about 6 per cent. of phosphorus is the active corroding, agent in a boil in a furnace; and that boiling cannot be said to be the result of the chemical action of a high-phosphorus slag on a basic bottom. These are well-established facts that no one would venture to question. The authors were misinterpreted in the statement that "in the summary, it is claimed that magnesite low in lime, or of greatest purity, ranks first in resistance to slaking," etc. On the contrary, the position has been taken throughout that while a low lime content is advantageous, the presence of several per cent. of iron oxide (an impurity), is necessary in order to confer the proper bonding and sintering properties in dead-burned grain magnesite to be used for furnace hearths. We cannot subscribe to the view that pure magnesia is no better fitted for a refractory than pure lime,' nor that the pure natural varieties of magnesite; such as Grecian or Washington, must necessarily be burned with silica and oxide of iron to produce a satisfactory material. On a small scale, pure magnesia has been satisfactorily used as a refractory in the form of crucibles. In the production of dead-burned grain magnesite from the Grecian or Washington mineral, iron oxide is added but the addition of silica is neither customary nor desirable. It is possible to manufacture brick of good quality from both the Grecian and the Washington material without adding either silica or iron oxide, providing they are burned at a sufficiently high temperature. This is regularly done on a commercial scale both in America and abroad when brick of. exceptionally high refractoriness or special purity are desired. The following analysis is of an English brick of Grecian magnesite which is extremely low in all impurities.1

Jan 6, 1919

By R. R. Klimpel

The process of flotation is an extremely important solids separation technique employed in a wide variety of industrial process applications. Froth flotation is practiced in the coal industry to recover fines produced during the mining and cleaning of coal. A recent review article by Aplan (1) covers the processing variables encountered in the flotation of coal and the variety of chemicals and operating conditions which affect recovery. Numerous engineering and scientific studies have been performed with the goal of providing semifundamental laws of flotation behavior for improved screening of flotation chemicals, better equipment scale-up factors, etc. Often the results of such work are expressed in the form of mathematical models (e.g. 2, 3, 4, 5, 6) which are potentially useful for evaluating (simulating) on paper such alternatives as possibles process operating or configuration changes, the effects of ore and reagent changes, etc. It appears to be commonly accepted that a complete scientific/engineering characterization of flotation is immensely complicated and not sufficiently developed at the present to accurately predict (or understand) many important industrial facets of flotation. Thus, one is often reduced to detailed experimental characterization in both the laboratory and plant in order to fully evaluate flotation changes or alternatives. It is the purpose of this paper to describe a method of batch laboratory data characterization that is useful in evaluating flotation chemical reagents including froth flotation of coal. The approach consists of running a series of time-recovery curves in a batch float cell followed by the computer curve fitting of this data to a series of mathematical models based on semi-physical reasoning. The unknowns or parameters of these models are then optimally chosen so as to best fit the experimental data. It has been found in both coal and mineral systems that changes in reagent type, concentration, system pH, grind, etc. cause very consistent and logical changes to

Jan 1, 1979

By Vladimiros G. Papangelakis

During the past five years, chemical modelling work at the University of Toronto has elucidated the role of soluble magnesium on the autoclave acidity and has demonstrated why feeds rich in magnesium, and other divalent metals, require more than the stoichiometric requirements in acid to produce a leaching performance comparable to that of low magnesium feeds. This understanding has allowed the calculation of acid additions to the pressure acid leach (PAL) on a less empirical basis. Optimizing acid additions to the PAL confers savings in neutralization costs, ensures high productivity and minimises corrosion problems. Hence, our picture of the solution chemistry inside the autoclave during the PAL process has been substantially improved and is reviewed here. Experimental techniques based on solubility and direct acidity measurements that support the theoretical predictions are presented. Concepts of chemical modelling of electrolyte systems at high temperature and software issues are also discussed. Finally, a better understanding of the solution chemistry at temperature has led to better kinetics models because all metal dissolution and precipitation reactions are acid driven and controlled. . Therefore, reactor modelling efforts by our group are also presented and a reactor model with very good performance, as compared to pilot-plant data, is also made here. Finally, in spite of the above success in PAL solution chemistry and reactor modelling, significant challenges lie ahead in theoretical data gaps and instrumentation; these are also discussed in this paper. Keywords: Laterites, process modelling, pressure acid leach, solution chemistry, chemical modelling, reactor simulation

Jan 1, 2004

By John Birkinbine

Through the partiality of my fellow-members I have been able, during seven years' service on the Council of the American Institute of Mining Engineers, to note the development of technical societies, a subject which commends itself as an appropriate theme for me, in retiring from the office of President, at a time when we meet in convention with Canadian technical societies. Our next assembly, called at Chicago at the time fixed for an International Engineering Congress, offers additional reason for the selection of this topic. If subsequent statements appear to give to the American Institute of Mining Engineers greater prominence than to kindred organizations, they may be excused upon the ground of long association with and loyalty to its members, and to a personal knowledge of their work. Besides, data as to its growth and development are more accessible; and at a meeting of the Institute features connected with it may be considered as of greater immediate interest than those affecting other organizations. The purpose of this address is, however, to use the record of the Institute as indicating a similar development of other technical societies, rather than to claim preeminence for any organization; the work of each must speak for it. There is a general tendency to form associations at the present time. Organizations have been created and are active in every profession and in all branches of labor, trade, industry, commerce, manufactures, science and art. A record of such associations and their aggregate membership would be startling, and would show how large a percentage of the population of North America is connected with one or more of them; but the figures cannot be even approximately estimated. The class of associations representing national, state, or local trade interests, such as boards of trade, chambers of commerce, etc., may be used as an illustration. A late report shows that in the

Jan 1, 1893

By Ralph P. Hackl

The Congress gold property, located near Goldbridge, B.C., is extremely refractory with most of the gold disseminated in fine- grained arsenopyrite. Metallurgical testwork conducted by Giant Bay Biotech Inc. indicated that biooxidation pretreatment was capable of increasing cyanide gold recovery from the ore to greater than 90%. To determine if the bioleach process could be successfully scaled up, a 225 cubic meter commercial size bioleach reactor was built and tested at the mine site in 1989. At that time the tank was the largest bioleach reactor ever operated. This paper discusses our experiences in operating the tank, summarizes some of the data obtained and describes the problems encountered.

Jan 1, 1990

By J. Mizera, J. Zdunek, K. J. Kurzydlowski, A. Dobkowska

This work concerns comparison of corrosion resistance of the aircraft aluminum alloy composed of Al - 2.3%Li - 0.1% Zr. The alloy was hot rolled (HR) from 13 mm to a thickness of 4 mm (e = 2.4) and 1 mm (e = 5.2). Corrosion resistance was investigated by Potentiodynamic Polarization Test. The investigation relied on exposure samples in two different corroding medium: 0.5 M NaCl solution and 0.01 M Na2SO4 solution with added 0.01% of Cl- at room temperature. Furthermore, the microstructure was analyzed using the optical microscope with polarized beam. The hardness was measured on lengthwise profile. It was stated that alloy after the largest deformation (equivalent total strain e = 5.2) is characterized by the best mechanical properties and the best corrosion resistance. The alloys in initial state and after deformation to 4 mm (e = 2.4) are characterized by worse corrosion resistance. It is associated with microstructure and density of dislocation in analyzing material.

Jan 1, 2015

By C Mpodozis

Central Andean (22¦S to 34¦S latitude) Miocene giant ore deposits share common features that reveal their origin. Tectonic and magmatic features include a relation to a shallow subduction zone, an association with the waning or initiation of a magmatic episode, emplacement at the time of uplift associated with crustal thickening and formation at times of major magmatic changes along the Andean margin. Rare Earth Element (REE) signatures in magmas erupted near the time of mineralisation indicate a progressive change from equilibration at depth with a hydrous, intermediate-pressure amphibole-bearing mineral residue to equilibration with an anhydrous high-pressure garnet-bearing assemblage. These features point to a common history. First, a relatively shallow subduction zone leads to hydration of a cool mantle wedge providing a source of fluids which builds up over at least several million years. Arc magmas formed at this time equilibrate with a hornblende-bearing residual mineralogy. Second, a compressive tectonic regime leads to crustal shortening and thickening that facilitates entrapment of arc magmas in the crust. Eventually, the magma-weakened crust yields to horizontal compression causing rapid crustal thickening. Fluids required for mineralisation are liberated as amphibole-bearing assemblages break down to garnet-bearing ones and over pressured fluids are released from plutons. Mineralisation subsequently ceases in the region unless continued dehydration of the slab and mechanical thinning of the continental lithosphere causes the previous conditions to repeat. The type of mineral deposit generated depends on the pre-existing continental lithosphere and the distance from the trench.

Jan 1, 1999

By T G. Measham, D A. Fleming

When attempting to understand potential regional or community socio-economic changes that resource-extraction industries may produce, it is important to analyse the channels that promote these changes. In this study, we propose a conceptual framework to better understand how socio-economic effects are likely to emerge in regions impacted by mining. The framework considers three levels of hierarchical effects (Measham, Fleming and Schandl, 2016).In the first level, the resource-extraction industry causes four direct initial impacts on nearby communities: labour demand shock (mining employment generation), income generation (compensation to landowners and higher wages), environmental consequences and land tenure/Aboriginal issues and an increase in local tax revenues.The second level is shaped by the subsequent population increase (given by immigration of permanent or temporary residents) produced by the new levels of employment and income that resource windfalls can generate in resource-extraction regions. These increases in employment, income and population become the source for a rise in the demand for local (and non-local) goods and services.Finally, the third level is given by boomtown-like and other socio-economic effects generated from the initial effects.CITATION:Measham, T G and Fleming, D A, 2016. A conceptual framework to understand the local community/social impacts of mining, in Proceedings Life-of-Mine 2016 Conference , pp 188–190 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By Chigova. Terence

In 2008, Anglo installed the Modular IntelliMine® System at its Kleinkopje Mine (AKK). As part of this deployment, Anglo also used the Change Management Consulting Service offered by Modular to ensure a successful installation. This paper outlines the benefits that AKK has realized through the deployment of the system, including a 15% improvement in tonne/kilometers per hour (TKPH). The mine benefited from the improvements provided by the system almost immediately by utilizing change management to more effectively integrate IntelliMine technology into their processes. This case study includes details about the deployed system, the implementation of change management, and recommendations to ensure success in future projects.

May 1, 2010

By Samer Sadek, David I. Smith, Wai-shing Lee, Jeffrey L. Rice, Avelino Alonso

INTRODUCTION East Side Access (ESA) Contract CQ028 is located in the New York City Borough of Queens. The contract involves construction of a 230-meter (760-foot) long open-cut excavation with a permanent deck supporting Amtrak yard tracks over a semi-circular TBM launch wall on the east end, and the 36.5-meter (120-foot) long Northern Blvd. Crossing on the west end. The Northern Boulevard Crossing will be mined under an existing New York City Transit (NYCT) five-track subway tunnel; Northern Boulevard, a heavily traveled five-lane truck route; and an existing NYCT three-track elevated line; connecting to an existing open-cut shaft adjacent to the existing 63rd Street Tunnel bellmouth. When completed, Contract CQ028 will provide access for future Manhattan and Queens tunnel contracts. The footprint of the open-cut was determined by the geometric requirements of the future Plaza Interlocking facility to be constructed within in another future ESA contract. See Figure 1. This paper discusses design risk mitigations for the key elements of the contract, namely the Northern Blvd. Crossing and the semi-circular TBM Launch Wall. PROJECT OVERVIEW The Metropolitan Transportation Authority Capital Construction Company—East Side Access Project for the Long Island Rail Road will provide Long Island commuters with direct access to Manhattan’s East Side via a new rail line between the Harold Interlocking in Queens and Grand Central Terminal in Manhattan. The project connects the unused lower level of the existing tunnel under the East River at 63rd Street to new connecting tunnels in Queens and Manhattan. Contract CQ028 Scope and Construction Schedule This contract consists of the excavation of an open-cut from the east side of Northern Boulevard, through an existing MTA-owned rail yard and into the western limits of Amtrak’s Sunnyside Yard. The contract will connect to a completed open-cut

Jan 1, 2007

The Waste Isolation Pilot Plant (WIPP) is adding a third fan to operate in parallel with, and supplement, its two existing main fans. An engineering analysis conducted in 1995 identified the need for improved system availability and efficiency. The WIPP, located near Carlsbad, New Mexico, is a U.S. Department of Energy (DOE) Carlsbad Area Office facility designed to permanently dispose of U.S. defense-generated transuranic waste in a deep bedded salt deposit. Engineers at the WIPP performed a feasibility analysis for either modifying, supplementing, or replacing its two main mine fans. Since the centrifugal fans were installed in 1988, multiple operational and performance concerns have been identified. A comprehensive engineering study was conducted (K. McDaniel, et al., 1997) to: identify and quantify operational concerns, evaluate possible alternatives, and recommend an optimum solution. The study indicated that adding a third single-duty centrifugal fan similar to the two existing fans, and equipping that fan with Inlet Van Controls (IVCs) was the best choice. This alternative provided the most desirable combination of operational readiness, and improving system performance. The fan installation project accommodates several operational and scheduling constraints. WIPP is scheduled to receive waste in May 1998. This milestone is proceeded by an operational readiness review. Fan installation could not be allowed to compromise the WIPP's ability to declare facility readiness and had to minimize operational disruptions during the system tie-in. All engineering for the project is completed and physical modifications started in July 1997. The project will be completed in early 1998.

Jan 1, 1998

By K. H. McDaniel

The Waste Isolation Pilot Plant (WIPP) is adding a third fan to operate in parallel with, and supplement, its two existing main fans. An engineering analysis conducted in 1995 identified the need for improved system availability and efficiency. The WIPP, located near Carlsbad, New Mexico, is a U.S. Department of Energy (DOE) Carlsbad Area Office facility designed to permanently dispose of U.S. defense-generated transuranic waste in a deep bedded salt deposit. Engineers at the WIPP performed a feasibility analysis for either modi tying, supplementing, or replacing its two main mine fans. Since the centrifugal fans were installed in 1988, multiple operational and performance concerns have been identified. A comprehensive engineering study was conducted (McDaniel, et al., 1997) to: identity and quantity operational concerns, evaluate possible alternatives, and recommend an optimum solution. The study indicated that adding a third single-duty centrifugal fan similar to the two existing fans, and equipping that fan with Inlet Van Controls (IVCs) was the best choice. This alternative provided the most desirable combination of operational readiness, and improving system performance. The fan installation project accommodates several operational and scheduling constraints. WIPP is scheduled to receive waste in May 1998. This milestone is proceeded by an operational readiness review. Fan installation could not be allowed to compromise the WIPP's ability to declare facility readiness and had to minimize operational disruptions during the system tie-in. All engineering for the project is completed and physical modifications started in July 1997. The project was completed in 1998.

Jan 1, 1999

By Yang Song, Li Shaokang, Wang Zhiqiang, Wang Jinjun, Li Guofeng, Su Meixuan

The paper investigates the triboelectric charging properties of calcium carbonate (CaCO3) particles under different conditions using a cyclone tribocharger. It explores the effects of airflow velocity, tribocharge material, and particle moving distance on the charge-to-mass ratio of CaCO3 particles. The study aims to provide guidance for the design of triboelectric separation systems for magnesite.

Sep 1, 2023

By Raymond B. Ladoo

[Inquiries are frequently received by the Bureau of Minas relative to occurrence, mining, treatment and utilization of the natural hydrocarbons' such as gilsonite, elaterate, wurtzilite, grahamite, and ozokerite although have been known and used for many years, they are not yet well understood and the amount of recent literature dealing with them as comparatively small. This paper is intended merely to summarize the present knowledge The natural hydrocarbons included in this series are gilsonite, elaterite, wurtzilite, glance pitch, manjak, grahamite, albertite, arid ozokerite and many other minor varieties. With the exception of ozokerite and the other mineral waxes, then all more or less resemble asphalt in that they are dark brown or black bituminous substances of organic origin, generally with a resinous luster. Ozokerite usually light an color with a waxey luster, is closely allied to the others of the series, but is usually considered separately, Unfortunately authorities differ as to nomenclature so that determinations of physical and chemical properties from different sources may riot be readily compared. Abraham Herbert, Asphalts and Allied Substances, 1918, 606 pp. has made one of the most detailed studies of these subjects in recent years, and his classification is used in the main. The following definitions are given by him]

Jan 1, 1920

By Kanaan Hanna

The integrity factor approach was developed by the Bureau of nines to assess the stability of mine pillars and has been applied primarily to longwall chain pillars. Recently this approach was applied to a room-and-pillar mine in the Illinois Coal Basin. A special configuration of hydraulic borehole pressure cells was installed in a pillar to determine the in situ strength-and- stress relationship of the coal pillar and to verify the applicability of the integrity factor approach. Results indicate that the integrity factor approach is applicable to the assessment of pillar st6b:lity and nay bs a realistic and effective approach for room-and-pillar mine design.

Jan 1, 1988

By Rudecindo S. Silo

[The principal characteristics of the process is that when applied in medium or in great degree it only needs unelaborated raw materials such as sodium chloride and calcium carbonate, or of medium elaboration, as sulphur which is found in large quantity in the North of Chili; however, the may be also applied to small copper plants provided that low cost sulphuric acid is available as a substitute for sulphur, that is, in. those plats of small capacity where large additional installations are not needed for the regeneration of the leaching solution. The method itself comprises 6 stages, namely: crushing, leaching, washing; of solutions, precipitation, regeneration of the leaching solution and fusion.]

Jan 1, 1965

By Frank Rausche

Without doubt, driven piles are the most economical deep foundation element for a nearshore environment, providing for high bearing capacities and stiffness, quick installation times, assured quality by simple monitoring and inexpensive dynamic load testing during restrike testing. However, when the pile top elevation is several meters below water surface, questions often arise as to the most reliable and economical pile installation method. Frequently encountered, yet relatively expensive, solutions include driving inside a dewatered cofferdam, driving long piles that are later cut off below water surface, or using an underwater hammer. Arguably, the most economical solution is driving the piles with a follower or chaser. However, many foundation engineers shy away from this solution because of the uncertainty associated with the transfer of energy through the interface between follower and pile, the associated potential driveability problems and maybe the limited fatigue life of the follower. This paper will demonstrate how the driveability of a hammer-follower-pile-soil system should be analyzed prior to installation and how to model the pile-follower interface both for steel and concrete piles. As an example, results will be presented which were obtained for both steel pipe piles and precast concrete piles, driven by a single-acting diesel hammer through a steel follower for a pre-construction test pile program in Venice, Italy. While analysis of the steel pile-follower system was straightforward, for the concrete piles, the presence of a soft cushion material whose material properties changed continuously posed some difficulty. Pile Driving Analyzer® measurements and CAPWAP® analysis yielded not only realistic stresses and transferred energy values in the pile, but also reasonable model parameters for further use in a pure wave equation analysis. As a side note for clarity, the dynamic measurements and analysis results herein presented are based on the GRLWEAP and CAPWAP software. GRLWEAP is commonly used all around the world for the preparation of pile driving jobs. The program either yields a bearing graph that relates bearing capacity and pile stresses to blow count or set per blow or it predicts blow counts and pile stresses as a function of pile penetration. These results allow the contractor to estimate driving time and select an economical hammer and driving system for a safe and efficient installation. CAPWAP on the other hand is the analysis of choice once a pile has been installed and records of pile top force and velocity have been acquired during installation or during a restrike test. CAPWAP is a signal matching program which calculates for one particular impact (for example at the end of driving) the static and dynamic soil parameters. Its final results include the calculated resistance distribution, the complete stress history in the pile and also a simulated load set curve. The CAPWAP calculated dynamic soil parameters can also be used in a Refined GRLWEAP analysis to generate a calibrated bearing graph."

Jan 1, 2006

By McPherson M. J

This paper describes a major ventilation study for the expansion of the El Teniente mine operated by Codelco, Chile. El Teniente is one of the world's largest under- ground mines. The design effort was under- taken in three stages and involved a partial mine ventilation survey with network simula- tion, detailed stope ventilation investiga- tions, and design of the entire mine ventila- tion circuit based on production plans to achieve 112,000 tons per day by 1995. The partial ventilation survey provided values of representative friction factors and resistances for typical ventilation raises and airways. These values were used to conduct detailed modeling of the block caving levels to investigate the most cost effective and practical means of providing the required ventilation. The results of these analyses were extrapolated to the proposed expanded mechanized zones.

Jan 1, 1988