Search Documents

By J. H. Meza Viveros

This paper describes some actual parameters and technologies used at Mexicana de Cobre Smelter, and the principal design parameters and new technologies which wiil be used with the smelter expansion project, in order to increase the production capacity of anode copper from 180 000 mtpy to 300 000 mtpy. Likewise its describe some parallel projects under construction also in the smelter plant.

Jan 1, 1997

By J. Boisvert, E. Daniels, C. Deutsch

"INTRODUCTION Conventional mine planning is performed on a single resource model at a selective mining unit (SMU) scale deemed appropriate for the deposit and mining method. Estimation methods such as kriging and inverse distance, commonly used to construct a single model, are susceptible to histogram smoothing (Rossi & Deutsch, 2014). This can be mitigated by limiting the number of composites per estimate, therefore correctly reproducing the distribution of estimates (Boisvert & Deutsch, 2012). Search limiting techniques remedy histogram smoothing at the cost of introducing a problematic conditional bias (Isaaks, 1999) and introduces even greater spatial smoothing. Localization is an alternative, offering histogram reproduction through post processing of more robust probabilistic modeling techniques. A single localized model at the SMU scale is desirable. The correct histogram can be reproduced and a single model allows for the use of conventional mine planning and resource evaluation techniques. Despite the advertized benefits of localization, the necessary reliance on a larger panel scale as a middle step in the localization process yields unsightly “edge-effect” artifacts (Boisvert & Deutsch, 2012). Two approaches to artifact reduction are presented here. The first is a straight forward optimization approach designed to minimize an objective function that penalizes artifacts including panel edge discontinuities to generate a model free of panel edge-effects. The second approach redefines a panel in a less conventional fashion as a randomly chosen set of SMUs throughout the domain. This method produces a model void of any regular panel shape resulting in an artifact free model. Artifact reduction minimizes the obvious “edge-effect” issues of localization but local precision issues described by Boisvert & Deutsch (2012) persist. Localization is not a replacement for quantified uncertainty for comprehensive risk analysis and resource evaluation. LOCALIZATION Initially developed with Uniform Conditioning in mind, localization collapses a distribution of local uncertainty at a panel scale to an SMU scale model for mine planning (Abzalov, 2006). This process has been extended to Indicator Kriging (Hardke, 2011), Sequential Gaussian Simulation (Boisvert & Deutsch, 2012) and MultiGaussian Kriging (Daniels and Deutsch, 2014). The localization process is performed in a similar fashion regardless of which technique is chosen to create the prior model of uncertainty. Methodology There are three scales of importance considered in the localization process. The point scale, otherwise known as the data scale, is the smallest and is the scale at which experimental data is collected. The SMU or block scale is the familiar scale at which mine planning and resource evaluation takes place. Lastly, the panel scale is larger and contains a number of SMUs. Each of the three scales is illustrated in Figure 1."

Jan 1, 2015

By T. W. Camm

Some of the defining characteristics of narcissists include a grandiose sense of self-importance, preoccupation with success and power, a sense of infallibility, and a supreme confidence in their ability and intelligence. Ironically, many of these characteristics are rewarded in business organizations, which may explain why there seems to be so many narcissists in management positions. Assuming we will be dealing with narcissists throughout our career, it makes sense for us to understand what makes them tick, and more importantly what we can do to work with them in a constructive manner.

Feb 23, 2014

By Terry W. Engelhart

"A computer-based approach to online supervisory control and operations management of bulk materials handling terminals". This paper describes an integrated computer facility supporting the functions and responsibilities of shift operations, scheduling, maintenance and management using real-time interactive techniques. The functions and responsibilities as related to coal export terminals are specifically addressed, although these functions would be equally applicable to other terminal configurations and other commodities. A discussion of the resulting benefits are presented: - throughput efficiency - long-term planning and scheduling, using simulation - operations monitoring and protection - demurrage/despatch optimization - preventative maintenance - operational productivity

Jan 1, 1982

By R. H. Weiland

The dewatering of flocculated clay suspensions by compression in a centrifugal field has been investigated. The results are evaluated with regard to both direct applicability to centrifugal dewatering, in solid-bowl centrifuges for example, and indirect applications to gravity sedimentation systems. It is well known that sediment consolidation under gravity depends on structural characteristics such as permeability and on the "self-weight" of overlying sediment layers. An important objective of the study has been to evaluate the self-weight effect using centrifugal forces to simulate consolidation in deep sediments. In this way, small-scale laboratory tests can be used to predict the rates and limits of sediment compression in industrial systems such as thickeners and settling ponds. Experiments have been conducted in which the sediment mass and initial structure were maintained constant while the effective sediment weight was varied by centrifuging at different speeds. The effects of initial structure have also been studied using controlled variations in flocculation conditions.

Jan 1, 1993

By David M. Abbott

This paper is a companion to, and amplification of, the ?History? section of the 2014 version of the SME Guide for Reporting Exploration Results, Mineral Resources, and Mineral Reserves (SME Guide). The need for the careful examination and evaluation of mineral deposits has long been recognized. In the book De Re Metallica, Georgius Agricola noted, ?Moreover, a prudent owner, before he buys shares, ought to go to the mine and carefully examine the nature of the vein, for it is very important that he should be on his guard lest fraudulent sellers of shares should deceive him? (1556, p.29). Agricola further stated, ?Now a miner, before he begins to mine the veins, must consider seven things, namely: the situation, the conditions, the water, the roads, the climate, the right of ownership and the neighbors? (1556, p. 30). The elements of Agricola?s seven things, much expanded, are incorporated into the 2014 SME Guide. As reflected in this quotation, veins were the primary concern of mining until 20th century technology permitted bulk mining techniques. The need for standardization of reserve descriptions arose along with the development of western mining in the United States and the concurrent development of mining engineering and mining geology as professions. By the turn of the century, debate about terminology of various classes of reserves was in full swing. Herbert Hoover noted in 1909 (p. 16-17), ?The old terms ?ore in sight? and ?profit in sight? have been of late years subject to much malediction on the part of engineers because these expressions have been so badly abused by the charlatans of mining in attempts to cover the flights of their imaginations. A large part of Volume I of the Institution of Mining and Metallurgy has been devoted to heaping infamy on these terms, yet not only have they preserved their places in professional nomenclature, but nothing has been found to supersede them. ?Some general term is required in daily practice to cover the available field of visible ore, and if the phrase ?ore in sight? be defined, it will be easier to teach the layman its proper use than to abolish it. In fact, substitutes are becoming as badly abused as the originals ever were. All convincing expressions will be misused by somebody.? Hoover (1909) noted that the common terms at the time were: ? Positive ore or ore developed: Ore exposed on four sides in blocks of a prescribed size. ? Ore blocked out: Ore exposed on three sides within a reasonable distance of each other. ? Probable ore or ore developing: Ore exposed on two sides, ? Possible ore or ore expectant: Ore in whole or in part below or beyond the range of vision. Hoover stated that these, and similar terms, overlapped and had the difficulty of failing to account properly for geologic variation in metal distribution beyond the exposed face. Certainly assuming extension of values along a vein is reasonable, but how far? Also, these definitions are for vein deposits, not all types of deposits are in veins. Hoover (1909, p. 19), therefore, defined the following terms. ? Proved ore: Ore where there is practically no risk in failure of continuity. ? Probable ore: Ore where there is some risk, yet warrantable justification for assumption of continuity. ? Prospective ore: Ore that cannot be included in the above classes, nor definitely known or stated in any terms of tonnage.

Feb 1, 2014

By I. Duckworth

P.T. Freeport Indonesia operates a mining complex located in the highlands of Papua, Indonesia. This district consists of underground and surface operations. The East Ertsberg skarn system (EESS) is one of the major orebodies in this district. Subsurface caving of the EESS has been carried out in a systematic series of mining lifts dating back almost 30 years. Present production from the third lift deep ore zone (DOZ), has reached 80 kt/d (88,000 stpd) during 2010, with this rate sustained through 2015. The orebody was proven below the existing caving level, with the next vertical block called the deep mill level zone (DMLZ).

Jan 1, 2010

While SME is hosting its Annual Meeting at the Phoenix Convention Center, Feb. 28 to March 3, one of the finest collections of mining history will be on display just 15 blocks away at the Arizona Mining and Mineral Museum. Inside the museum, visitors will be treated to a treasure trove of minerals, gems, me¬teorites, rocks, fossils, mining artifacts, historical exhibits and interactive displays on modern mining. The museum is located at 1502 West Washington. For SME Annual Meeting attendees, this is a free, eight-minute Dash bus ride 15 blocks west of the Phoenix Convention Center.

Jan 1, 2010

By I. B. Tulu, M. M. Sears

In 2015, 40 longwall mines provided nearly 60 percent of U.S. underground coal production. During this time, about 80 percent of ground-fall-related fatalities occurred in areas where the mine roof was supported. In an attempt to better understand the status quo of current longwall support practices in the United States, during a period between 2010 and 2017, researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH) visited a sample of 25 longwall mines representing nearly 50 percent of the currently active longwall mines operating in all of the major U.S. longwall producing regions. The data presented here indicate that the types and amount of roof support being installed in modern U.S. longwall mines have reduced ground-fall accident and injury rates to levels never seen before. However, the complete elimination of unintended roof falls in U.S. longwall mines has remained elusive. The data in this paper can be used by mine operators and engineers to determine where their chosen type and density of roof support occur on the spectrum of observations contained in this database. Additionally, this data can be used to enhance, supplement and support additional research on longwall gateroad support systems. 

By J. H. Gasper

A cost analysis for two alternative contour mining methods is performed to compare their results. The methods evaluated are: 1) Front-End Loader/Truck Haulback and 2) Scraper Haulback. Before performing these analyses, output requirements and equipment needs are found based on integrating geometric limitations with material properties. The final geometric design establishes limits on clearances, congestion problems and grades (with associated running surface materials). All calculations are kept practical, with assumptions clearly stated. The cost analysis is a unique, easily utilized compilation of several different approaches incorporating cost engineering principles. The strengths of each are welded into a cohesive entity once again aimed at practical application. The results are presented in tabular form.

Jan 1, 1992

By Klaus Rabensteiner, Klaus Chmelina

"INTRODUCTION Urban tunneling is often related with special geotechnical risks. Typical causes are difficult (hydro)geological conditions, a very low overburden and the presence of critical and vulnerable (infra)structures in the influence zone of the construction (e.g. existing tunnels, roads and pavements, sewer pipes, gas and power lines, landmarked buildings, historic monuments). To manage these risks appropriately, an early detection and warning of unexpected behavior of the affected geotechnical objects ground and tunnel, as well as existing structures are mandatory. To accomplish this, the design and execution of a dense geotechnical monitoring program is of high importance. In more detail, this means specifying and performing a systematic and continuous acquisition, processing and analysis of monitoring data to support decision making. In recent years the development of new automatic sensors and (wireless) data transfer techniques and the general trend towards an automatic acquisition of monitoring data has led to an enormous increase of data production frequencies and volumes. In order to handle this data explosion efficiently, information systems and geo-databases have been developed and used successfully in many projects. They represent IT tools that support the different tasks of a given geotechnical monitoring program including data acquisition, transfer, check, processing, backup, analysis, distribution, reporting and, last but not least, alarming. Meanwhile, some tools already have developed the capability to connect to other theme-specific databases used in the project and, thus, serve as a central data management system for all kind of digital data produced. This makes possible the implementation of further useful functions and services supporting tunneling tasks such as machine control, tunnel simulation, geological prediction, process optimization, etc. where data from different engineering disciplines must be combined and processed in an integrated way. In the following chapters our aim is to describe how monitoring data management, geotechnical monitoring, alarming and reporting are organized and technically implemented at the metro project Cityringen in Copenhagen (Denmark). We want to highlight the specific role and tasks of the used tunnel information system in the project, and particularly inform on the most relevant challenges."

Jan 1, 2016

By Eugie Kabwe

The effective employment of a pretensioned bolt within support structures requires an appropriate installation tension as a result of sufficient bolt head/nut preload. In this paper, a load indicator washer (LIW) able to withstand an assigned static loading as well as provide an appropriate pretension is presented. The different LIW breadths are numerically analyzed with ABAQUS finite-element code to estimate deformation when a designated 60 kN preload is applied. The numerical simulation employs the bilinear isotropic hardening constitutive law governed by the von Mises yield criterion. The simulation also considers the nominal temperature of the nut-LIW-rock bolt connection. Therefore, long-term relaxation effect on bolt pretension as a result of stress relaxation is neglected. The compressive force required to achieve the LIW predetermined deformation is the bolt pretension. It is drawn from the simulation results that LIWs with thicknesses of 1.5, 2.0, 3.0, 3.5 and 4.0 mm are completely flattened when subjected to 28, 42.5, 65, 76 and 88 kN preloads, respectively.

By Neal P. Cochran

The Office of Coal Research Program has been outlined in our Annual Report for a number of years and reported on by various members of the OCR staff as well as by our contractors. The program is national in scope and is intended to develop new and improved uses for our Nation's coal resources and to maintain coal in a favorable economic position, vis-a-vis, the other energy forms. A program has been developed that includes conversion of coal to gas, gasoline and other petroleum-type products, and to electricity. These projects are only one facet of the OCR program albeit an important one. In many of the conversion projects we have underway, original development work has been done with bituminous and sub-bituminous coal. It is the intention of this paper to present a general outline as to how lignite might fit into one or more of these projects as a raw material. Our national lignite reserves are vast in scope and this has been recognized in the OCR program by development of a project specifically for lignite and by including lignite as a test raw material in many other projects. Project Lignite is intended to develop the Cop Acceptor Process for conversion of lignite to a high B.t.u. gas. In this effort we have included the design, construction, and operation of a lignite gasification plant at Rapid City, South Dakota. The work is being conducted by the Consolidation Coal Company and is an outgrowth of their laboratory development of this process. The first portion of our effort included a detailed economic study of a somewhat arbitrary grouping of States designated Market Area A that could be expected to use gas manufactured in a lignite gasification plant. The area included the Dakotas, Minnesota, Nebraska, and Iowa. This geographical area could readily be served if a process could be developed for converting North Dakota's lignite reserves, estimated at 351 billion tons, to high B.t.u. gas. Our study showed that Market Area A had a potential commercial- industrial market of one trillion cubic feet of gas a year. To meet this demand, we believe that part of the load can be obtained from commercial lignite-to-gas plants. At the time of our original study, we concluded that gas could be delivered to the city gate in Market Area A at about 45¢. As a result of price escalation in the interim, our estimate today might be slightly higher, but not significantly so, since some parts of the process appear better today than they did at the time of the original projection.

Jan 1, 1968

By Roberto Carranza

The planning of experiments and the importance of statistical interpretation of the results have been recognized for years by scientists and engineers. The Factorial Design of experiments is among the various methods used for this purpose and is being widely applied in all branches of research and production. The basic principles of this tool have been described in detail (1, 2, 3, 4) and several examples of its application in various fields have been published (5). In recent years the mineral industry has also used Factorial Design to improve the efficiency of research, testwork and plant operation (6, 7, 8, 9). This method permits for a qualitative determination of the influence of the variables studied in a process and also a qualitative measure of the interaction of the variables. By graphic means or derivative methods, one may also establish the optimum conditions of the process (ibid 7, 8, 9). It is desirable, however, to develop mathematical methods to evaluate quantitatively these effects and restrict the optimization to the practical limitations of the variables. It is also convenient to adopt a notation system to generalize the Factorial Design.

Jan 1, 1971

By R. W. Smith, J. Dubel, M. Misra

The bacterium Mycobacterium phlei is highly hydrophobic and negatively charged. It has specificity for selective adhesion to fine coal particles, mainly due to hydrophobic interaction. However, it does not attach to pyrite and ash forming minerals present in the coal matrix. Results have shown that this bacterium is an excellent flocculant for fine coal. Not only, are the coal particles visibly aggregated, but the optical micrograph has shown that the coal particles are held in the aggregate by adhesion and bacterial bridging. With Mycobacterium phlei, the flocculation characteristic of coal is markedly different from that usually observed with synthetic polymeric flocculants. In particular, the entwining characteristics of the long chain molecules of synthetic flocculants are absent in the case of Mycobacterium phlei. Since the hydrophobic interactions between the adhering particles are of greater importance in the formation of particle aggregation, the flocculation process is very selective.

Jan 1, 1994

By P. James

"INTRODUCTION High sulfate (SO4-2) levels often occur in MIW (mining influenced water) either as the result of oxidation of sulfide minerals exposed by mining activity or by deliberate addition – commonly by sulfuric acid (H2SO4) use in hydrometallurgical leaching activities. Increasing regulation of sulfate discharge is creating new pressure to treat or mitigate sulfate release to prevent its entry into the environment. Current treatments include precipitating as gypsum during lime treatment, filtration separation using membranes such as reverse osmosis and nanofiltration technology, and biological elimination via methods like constructed bioreactors. Blue Planet Strategies (BPS) focuses on improved resource utilization targeting electrolytic treatment and waste conversion into resources and has now demonstrated that its proprietary DEMET™ (Dynamic Electrolytic Metal Effluent Treatment) platform can also remove sulfate from target streams as a byproduct of its usual primary treatment focus points of metal species elimination and/or pH adjustment.[1-6] This powerful new capability can mitigate sulfate contamination and recover the sulfate in a useful and potentially saleable form as a byproduct of improved primary treatments focused on enhancing production or treating waste. This provides a new treatment opportunity and value proposition for lowering overall sulfate consumption/addition or creating new revenue to defray conventional treatment costs. The DEMET Alternative DEMET utilizes a patented electrolytic technology platform employing proprietary dynamic high surface area electrodes in innovative configurations to achieve a variety of novel selective chemistries. DEMET‘s unique elements can yield higher processing rates at practical efficiencies, lower energy consumption, plus improved processing stability and lower maintenance requirements due to enhanced resistance to cell fouling and shorting; while also thwarting cross stream (catholyte vs. anolyte) contamination. Consequently, DEMET can provide a superior, extremely versatile, and cost-effective electrolytic treatment option where a multitude of FEED and PRODUCT stream combinations might be employed in comparison to traditional tankhouse electrolytic cells. Secondary reactions (Figure 1A) which could also occur at the cathode (plating/electrowinning, precipitation/scale formation, etc.) are controlled through process tailoring and operation parameter selection. Additionally, DEMET‘s innovative dynamic system mitigates potential fouling and electrode occlusion or shorting challenges which could occur when process particulars demand some of these secondary side reactions occur."

Jan 1, 2015

By James J. Scott

Three dimensional photoelastic techniques have been developed which provide information on the state of stress at any point in a model investigated. This investigation utilizes these techniques to determine the stress distributions in the pillars and the roof of a room and pillar mine model. Castolite plastic was used for the construction of the model in which a stress pattern was developed by the stress freezing process. Analysis of the stress pattern was accomplished by use of data obtained by observing points in slices from the model with a polariscope and solving data obtained by' the shear-difference method. Slices through the centerline, edge of pillar and centerline of span were investigated. Results of this work provide information on the overall stress distribution on points of stress concentration in compression, shear and tension, show relative magnitude of stress throughout the model and indicate directions of the most important stress values. A generalized roof bolt pattern is developed for room and pillar mines based on the stress distribution. A digital computer was used in the reduction of data and proved to be extremely useful for investigation of this type.

Jan 1, 1963

By R. M. Reyes, D. Negrete, G. Herrera

First Majestic Silver Corp’s La Encantada Silver Mine is a producing mine with a capacity of 3,000 tonnes per day. The La Encantada team is currently constructing two small-scale caving mines, including the San Javier breccia caving mine. The new mine is constructed within a mineralized breccia body composed of clasts of varying sizes and with very poor rock quality. Due to this poor rock quality, primary and secondary supports are required to support both the development and production stages. Since the proximity of the new mining levels to existing old workings, correct selection of the support system and proper production controls, instrumentation, and monitoring are very critical to maintain the stability of the pillars and fortification elements. An increased ground deformation due to the load transfer during the production stage is expected. This report reviews the primary and secondary support elements used in the different stages of mining, the monitoring of ground deformation, and the steps taken to analyze and visualize the collected data in order to enable the geotechnical team to manage caving stress and maintain pillar stability. INTRODUCTION First Majestic Silver Corp. (“First Majestic”) is a Canadian mining company focused on silver production in Mexico that operates six producing silver mines, including La Encantada Silver Mine (“La Encantada”). First Majestic acquired La Encantada in 2006. La Encantada is located in the northwestern portion of the state of Coahuila, in northern Mexico, in the municipality of Villa de Ocampo. The mine lies in the northern part of the Sierra Madre Oriental physiographic province. The mine location is shown in Figure 1. La Encantada is a producing mine, with a mill processing capacity of 3,000 tpd, and a 4,000 tpd capacity cyanidation leaching circuit equipped to process fresh underground ore and old tailings amenable to be reprocessed. The mine is currently employing several mining methods, including overhand cut and fill for narrow veins, small mantos, and other minor deposits. A subset of caving methods are applied on the larger, but weak, mineral deposits, such as at the San Javier breccia and La Prieta breccia. La Encantada consists of vein, manto, breccia pipe, and chimney deposits with concentrations of silver, lead, iron, and zinc in oxidized mineralization enclosed by calcareous sedimentary formations of Cretaceous age. At deeper levels, there is sulphide mineralization in skarn with zinc and silver concentrations associated with a granodiorite intrusion.

Jan 1, 2019

By Joseph B. Novak

In the last decade or so, the importance of effective preventive maintenance controls and practices has taken on a new and accelerated emphasis. Advances in technology and changes in equipment and product designs impose more precise and demanding standards of quality, productivity and customer service at a very rapid pace. Daily, it is becoming more apparent that in order to fulfill current requirements, existing manufacturing practices and associated control programs must also be upgraded and expanded. This is particularly true in the field of maintenance services. As production and quality standards become more demanding, effective equipment maintenance takes on more importance and becomes more difficult to sustain. In modern plants, the failure of a single equipment component can shutdown a complete production line causing interruptions to operating and shipping schedules that result in costly downtime, dissatisfied customers, and reduced profits. These costly experiences can be minimized with an effective maintenance program that provides maximum equipment reliability and minimum downtime and readily adapts to revision and change. A significant feature of an effective program is the provision of controls over activities generally identified as

Jan 1, 1971

By Kim Lapakko

Increasing public concern over the welfare of the environment has placed demands on the mining industry to evaluate the environmental impact of mining development. This is a difficult task and involves considering the influence of a multitude of variables on complex processes over a long time period. Few studies which focus on the evaluation of the environmental impact of mining have been conducted and, therefore, there is little past experience to rely upon. This article describes some of the work done to evaluate the potential environmental impact of mining development in Minnesota. Interest in developing the major copper and nickel sulfide deposits near the wilderness areas of northeastern Minnesota aroused concern regarding the environmental impact of mining development in the region. As a result laboratory and field studies were initiated to investigate the potential for trace metal leaching and acid generation due to dissolution of Duluth gabbro. Chemical equilibrium computer modeling was conducted to aid in data interpretation. The goals of the study included the investigation of leaching mechanisms and rates of release (1, 2).

Jan 1, 1980