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By D. G., Bosse&apos

Equipment choices for ultrafine grinding encompass several different types of dry and wet size-reduction devices. These need to be put into functional perspective for systematic analysis of capabilities and limitations versus processing requirements of the materials to be satisfactorily ground. Particle strengths plus maximum and average sizes are the primary variables controlling grinding action requirements and equipment options for efficient processing. These are fairly well understood and provide the starting point for decisions. Particle space requirements under dynamic processing conditions vary with particle shapes and size-distributions by as much as 30X. This additional major variable is not widely appreciated and does need adequate description to provide a firm basis for selecting processing compositions and procedures.

Jan 1, 1983

By A. Fuerst

This paper delivers insights into how high availability combines with high efficiency at the Yanacocha Plant, Newmont Mining Corporation, Peru. Advances in motor design and maintenance with integration of smart control support the approach plant maintenance staff is applying to deliver such excellent results for availability and efficiency in Yanacocha and elsewhere. Detailed efficiency and availability data for 2011 and 2012 in Yanacocha are provided. ABB and Yanacocha teams collaborate closely by combining their experience and continuous development of gearless mill drive procedures and maintenance knowledge to deliver the impressive performance being achieved. The secrets for high performance shared by the Yanacocha maintenance operations point to their systematic, practical adherence to modern asset management and maintenance concepts.

Feb 27, 2013

By G. D. MacDonald

The Grasberg porphyry copper-gold deposit of P.T. Freeport Indonesia, Co. is located in the Jayawijaya Mountains of Irian Jaya, Indonesia approximately six km west northwest of Puncak Jaya, the highest point on the island of New Guinea. Disseminated mineralization is confined to the Grasberg intrusive complex, a multiphase intrusion of dioritic to monzonitic composition which intruded tightly folded carbonate rocks of the Tertiary Faumai and Ainod formations. The high tonnage and grade of the deposit (1 X 109 tonnes at 1.4 % copper and 1. 8 ppm gold) appear to result from a succession of coincident intrusive and mineralizing events about three million years ago. This paper will focus on the history and character of these events.

Jan 1, 1993

By William Kohan

The industrial grinding process has undergone changes to better address the market and economic needs. Fine grinding of dry materials has developed to the point where classifying linings and fine ball charges improve mill efficiencies. Roller mills as well have wide acceptance due to their power efficiencies. The mill, by its nature, cannot provide the specific particle size or range of sizes which are required for further processing or final use. Therefore, various separators are operated in conjunction with the mill to control particle size. The sizing device helps minimize over grinding and control top size. Rising energy costs combined with increasingly tighter quality specifications have led to increasing study of the grinding and separation process.

Jan 1, 1985

By A. M. Raichur

The selective adhesion of hydrophobic Mycobacterium phlei to coal particles is responsible for flocculation of fine coal from associated ash forming minerals. The driving force for the differential adhesion is the hydrophobic interactions between the fatty acid surface of the organism and hydrophobic nature of coal. The effect of Mycobacterium phlei on surface hydrophobicity, surface charge and mechanism of adhesion on coal and associated minerals are controlled by several factors including hydrophobicity and surface and solution chemistry of the system. Adhesion measurements indicate that maximum adhesion occurs below the isoelectric point (IEP) of the coal particles. While massive adhesion of Mycobacterium phlei is observed on coal, however, negligible amount of Mycobacterium phlei attaches to mineral pyrite and quartz.

Jan 1, 1995

By D. J. Miller

Environmental considerations are extremely important in planning and carrying out mergers, acquisitions and real estate transfers. It is not inconceivable that potential or actual environmental liabilities could exceed the targeted company's net worth or the book value of the real estate of interest. It is therefore essential that an environmental due diligence investigation (DDI) be performed to quantify environmental liabilities before sales, mergers or acquisitions. This paper will discuss general procedures used in environmental due diligence investigations. The emphasis will be placed on mergers and acquisitions. It should be pointed out that the procedures discussed in this paper are general and must be modified to fit each particular merger or acquisition under consideration.

Jan 1, 1988

By N. K. Riddle

In many mines, it is typical to stockpile material for milling based either on analyses from exploration and blasthole drilling, or on the observation and judgment of experienced personnel. New analytical instruments make it possible to perform multiple, rapid analyses of as-mined samples at or near the mining face, so that sorting into stockpiles can be much more accurate. Using data and operating practices from a phosphate mine, a model was developed to simulate the function of analytical instruments in ore-grade control and ore stockpiling. With this model, it is possible to determine the recommended sampling points and sample frequency to obtain the desired confidence limits on the stockpile analyses.

Jan 1, 2003

By Bruce Kennedy, Dan Nilsson

Mining means drilling and blasting in order to break down the rock, loading and transport, and often also crushing the ore down to a suitable size. These operations can be done in open pits or in underground mines, and also, to a lesser extent, in marine mining. The same operations are also used in various types of construction, i.e., for roads, water power stations, etc. Before beginning a detailed economic analysis of the factors which enter into deciding whether to mine by open-pit or underground mining, and at what point a change should be made from open-pit to underground mining, or vice versa, it is of interest to consider some general factors.

Jan 1, 1982

By S. D. Thompson

Several discrete-event simulation models have been developed for designing the conveying system capacities of underground coal mines. Most of these models require the use of a step function approach to mimic the loading process at each conveyor loading point. Over the years, practitioners have generally employed one of three versions of the step function approach. An important issue is how these three versions compare to each; other in terms of simulated capacity requirements for belt conveyors. Another issue is how they compare to the peak capacity design. This paper addresses these issues by statistically and quantitatively comparing their simulation results. The consequences and problems associated with using each version are also discussed and summarized.

Jan 1, 1997

By D. G. Bosse

Equipment choices for ultrafine grinding encompass several different types of dry and wet size-reduction devices These need to be put into functional perspective for systematic analysis of capabilities and limitations versus processing requirements of the materials to be satisfactorily ground Particle strengths plus maximum and average sizes are the primary variables controlling grinding action requirements and equipment options for efficient processing These are fairly well understood and provide the starting point for decisions Particle space requirements under dynamic processing conditions vary with particle shapes and size-distributions by as much as 30X This additional major variable IS not widely appreciated and does need adequate description to provide a firm basis for selecting processing compositions and procedures

Jan 1, 1983

By Ch. Arvanitidis

This paper presents the design solution for an actual case of settlement tanks, for a wastewater treatment plant under construction, actually founded on swelling clay (the nature of which had not been appreciated beforehand) and suffering considerable damage as a result. Two points of interest prompted the use of a numerical model as an alternative approach to the traditional method of analysis: First, the desire to compare the in situ measured deformation and displacement of the tanks with the figures calculated by the numerical model. Second the need to check the validity of the suggested solution as a remedy, i.e. the replacement of a certain thickness of clay by graded material.

Jan 1, 2005

By C. Patrick, D. Puckett

The feasibility of monitoring the locations and vital statistics of equipment and personnel in surface and underground mining operations has increased with advancements in radio frequency identification (RFID) technology. This paper addresses the use of RFID technology, which is relatively new to the mining industry, to track surface equipment in mine pits, loading points and processing facilities. Specific applications are discussed, including both simplified and complex truck tracking systems and an automatic pit ticket system. This paper concludes with a discussion of the future possibilities of using RFID technology in mining, including monitoring heart and respiration rates, body temperatures and exertion levels; monitoring repetitious movements for the study of work habits; and logging air quality via personnel sensors.

Jan 1, 1999

By M. Menegaki

Restoration of abandoned mine sites is still one of the weak points of mining practice. The latter stands especially for the case of the surface coal and lignite exploitations, where the extended size of the disturbed land and the drastic changes to the geomorphologic features do not facilitate the implementation of a cost effective and environmentally sound reclamation plan. The paper examines the parameters involved towards the legal requirements for the reclamation of the first lignite exploitation in Greece, namely the ?Plakes? mine, located at Euboea, due to the particularities of the site. Then an integrated redesign procedure is presented, aiming at minimizing aesthetic degradation, confronting technical difficulties and preparing the site to accept new uses.

Jan 1, 2005

By T. Tamagawa, I. Iwasaki, N. X. Fu, M. Kobayashi

A low-temperature-chlorination selective oxidation followed by aqueous chloride leaching and SX-EW for producing electrolytic copper, elemental sulfur and ferric oxide was investigated for hydrometallurgical processing of a chalcopyrite concentrate. In this article, the selective oxidation phase of the process is described. The selective oxidation requires a temperature well above the CuCl-FeCl3 eutectic points. The test procedure was developed with a batch reactor and then tested with a continuous reactor. The process was initiated by adding small amounts of chlorinated samples to a fluidizing bed of dead-roasted sulfide concentrate micropellets. The selectively oxidized samples thus prepared were shown to fully dissolve copper, while virtually all the iron remained undissolved.

Jan 1, 2000

By J. Bigu

Use has been made of several theoretical models to predict radiation levels in underground uranium mines. The models used are the Evans model, the Thomas-Epps mine model, the isolated mine model, the mine tunnel with no air flow and the mine tunnel with air flow (Beckman and Holub). Calculations based on the above models have been extended to include thoron gas and its progeny, a common occurrence in some Canadian uranium mines. Theoretical predictions include radon and thoron progenies WLs and concentrations, and some ratios of great practical interest. The main differences between the models are pointed out and comparison is made with experimental data gathered during the last three years in several Canadian underground uranium mines.

Jan 1, 1981

By Deepak Malhotra, Robert Dorfler

Modern engineering mill design has been refined over the years to the point where detailed ore and process specification criteria can be developed In the engineering design phase of the project. The plant Is then built to the detailed criteria and performance acceptance tested by the owner to see if the as-built mill meets the criteria, This performance testing is critical to the owner; the test must be systematic with sample collection coordinated throughout the plant. Despite the availability of systematic approaches to plant development, the new plants often fall short of design criteria. This paper discusses the key Issues a Project Manager/Process Engineer should Implement to ensure that plants meet design criteria.

Jan 1, 1991

By S. D. Thompson

Several discrete-event simulation models have been developed for designing the conveying system capacities of underground coal mines. Most of these models require the use of a step function approach to mimic the loading process at each conveyor loading point. Over the years, practitioners have generally employed one of three versions of the step function approach. An important issue is how these three versions compare to each other in terms of simulated capacity requirements for belt conveyors. Another issue is how they compare to the peak capacity design. This paper addresses these issues by statistically and quantitatively comparing their simulation results. The consequences and problems associated with using each version are also discussed and summarized.

Jan 1, 1998

By Thomas F. Torries

It does not take sophisticated economic analysis to determine the current status of nickel production and demand (Figure 1). One only needs a quick glance at the balance sheets of the major nickel producers to learn that prices are down and profits are supressed to the point where they are major losses. Operations have been closed, and those remaining in production have reduced output. What Is now of interest Is, when will the nickel market improve and to what degree? The purpose of this paper is to attempt to answer these questions. This will be done by the normal method of projecting nickel demand, chosing a production scenario, and analyzing the results.

Jan 1, 1982

By William R. Bond, Jim V. Rouse, Laura L. Damon

As noted by Damon (1990), "The time that a heap (of gold ore) is on the reusable leach pad is of critical economic importance." The Interim Neutralization Study, conducted by Brohm Mining Corporation (Brohm), at the request of the South Dakota Department of Water and Natural Resources and reported by Damon indicated that improvements could be made in leaching and pointed out the need for a better understanding of the gold ore leach procedures. To provide data on an actual heap, personnel from Brohm and GEOCHEM installed a series of pressure/vacuum lysimeters in an active Brohm heap, and conducted subsequent testwork to evaluate the efficiency of leaching. The objectives of the testwork included efforts to:

Jan 1, 1992

By Thomas M. Goodell, Timothy D. Arnold

Dilute-phase pneumatic conveying has been used in the mining industry since the 1920s. It has primarily been used for the hoisting of coal and salt ores, and as a transportation medium for backfill material. More recently there have been investigations into a wider variety of applications, which this paper addreses. The paper will point out some deficiencies in the system. It 1s not the "champion" of the mining industry, but rather an excellent srste?1 with a variety of applications that may not have been studied m enough detail. The most imaginative applications to the Redpath Pneumatic Conveying System have been initiated by persons needing an innovative application to a specific predicament.

Jan 1, 1992