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By Thomas P. Meloy

A brittle solid broken by crushing or impact, results in a mass size distribution curve having a straight line segment when plotted on log-log paper. Depending on the mineral, the slope of this straight line segment ranges from a maximum of one for materials like glass and quartz to values of one half or less. Theoretical derivations of the size distribution, such as the Gaudin-Meloy model, yield a slope of one and only one. When the Gaudin-Meloy model is modified to assume that not all cracks terminate on a preexisting surface, the new model predicts that size distribution slopes, depending on the type of brittle solid, will be less than one. There is a measurable physical parameter that will predict the slope. In addition the model predicts that particles from such a size distributions will have negative corners and peaks - indentations. Moreover the model predicts that particle shape will systematically change with decreasing particle size. Finally, this new physical model of comminution may be experimentally tested.

Jan 1, 1995

By G. T. Adel

Hindered-bed separators are often used in the minerals processing industry to classify particles according to size and density. A new technology, known as the Eriez CrossFlow, was recently developed to overcome some of the limitations associated with hydraulic separators. The innovative feature of this unit is a novel feed presentation system that improves separation efficiency and capacity. In the present work, a detailed process engineering evaluation was conducted to determine the basis for the improved performance of this unit. The evaluation included controlled separation tests using well-characterized feeds, particle and liquid tracer experiments and mathematical modeling studies. Data obtained from this work show that the new separator is capable of maintaining good separation efficiencies at higher solid feed rates than traditional designs due to improved hydrodynamics in the separation zone. This paper reviews the operating principle of the Eriez CrossFlow separator, discusses the results of the tracer experiments and modeling studies and presents test data obtained from recent laboratory and plant trials. Key words: Size classification, CrossFlow separator, Hindered-bed separator, Hydraulic separator

Jan 1, 2003

By O. Guyot, A. Broussaud, J. Björkman, P. Söderman, P. O. Samskog

Model-Based Expert Control systems (MBEC) are on-line supervisory dynamic optimization systems which combine the ability of a phenomenological model to generate a large amount of information about the state of the process and predict its evolution, with the flexibility of a rules-based approach to take plant constraints into account and apply a complex control strategy. For its new concentrator started in 1995 in Kiruna (Sweden), LKAB has implemented a progressive grinding flowsheet with closed-circuit autogenous grinding followed by closed-circuit pebble grinding with ore pebbles. The standard for instrumentation in this new plant is very high. The control hardware consists of a Distributed Control System (DCS) through which the operators interact with the plant, supplemented by a site-level Management Information System (MIS). A state-of-the-art MBEC system was imbedded in the MIS by the authors before plant start-up. It consists of several modeling and expertise software modules: a phenomenological process model and a Kalman filter estimate continuously the state of the process, an optimizer calculates an optimum feedrate, while rules-based modules establish production targets and key process set-points. The decision to install the MBEC system as an integral part of the new plant before start-up illustrates the current maturity of the technology, i.e., enough know-how was accumulated through former projects to design and develop the system to a large extent without accessing the plant. The feasibility and the power of dynamic optimization systems were previously demonstrated in Kiruna pre-existing concentrator by the authors. First, a MBEC system was installed on the three existing pebble mill circuits, providing both an increase in quality (stabilised size distribution) and a 10% increase in capacity. An on-line expert control system with limited modeling capabilities was also installed in the existing flotation plant, with the aim of stabilizing phosphorous content in the concentrate and optimizing collector additions. Both objectives have been achieved.

Jan 1, 1995

By R. W. Smith, A. Raichur, M. Misra, I. A. H. Schneider

The concept of microorganisms as chemical reagents (flocculants, flotation modifiers and flotation collectors) is quite new. Potential uses for microorganisms include their use in place of certain conventional flotation reagents and as flocculating agents in minerals engineering processes. In addition, in some studies micro-organisms have been used to modify mineral surfaces and, thus, the flotation or flocculation of the minerals.

Jan 1, 1995

By Y. Tao

The professional status and characteristics of mineral processing were discussed along with the importance of innovative personnel training for mineral processing engineering. Reform ideas and models for the mineral processing engineering education system were suggested to formulate and implement new training program for the mineral processing specialty. It is suggested to strengthen engineering training practices, cultivate the culture of innovation, improve innovative education system and insisting on the combination of teaching with production and scientific research as the important means of training innovative talents for mineral processing engineering.

Jan 1, 2010

By H. V. S. Tingley, D. Helfant Ghose

"Ten years ago," said a mining industry personnel manager, "we used to wine and dine new mining engineering graduates. Now I can pick and choose among men with 10 years of experience." Comments like that are common throughout the industry today. During the 1970s, the US and Canada did indeed suffer from a severe shortage of mining engineers, especially experienced ones. Moreover, it seemed likely this North American shortage would worsen. Increased production of minerals and coal was pushing demand for mining engineers upwards, and there appeared to be substantial new employment prospects for them in the nascent synfuels industry. The oil majors entering the mining industry were pushing for an increased professionalization of mining management, heralding a trend towards higher intensity in the use of mining engineers. In response to the shortage, mining schools expanded their programs dramatically. By 1982, American schools were churning out more than 600 new mining engineers per year, compared to barely 200 in 1970 (Table 1). The timing of the explosion in the number of mining engineers could not have been worse. The downturn in the economy and the resulting slump in the mining industry coincided almost exactly with peak output of mining engineers. The market for mining engineers shifted from shortage to surplus with startling rapidity. The new crop of engineers, no longer courted by the mining companies, struggled to find any mining jobs. At the same time, experienced mining engineers found themselves thrown into the job market, some for the first time in decades. The current oversupply of mining engineers is assumed to be a temporary phenomenon. As the economy recovers, the demand for mining engineers is expected to pick up at least enough to absorb today's surplus. Not so, according to a recent study by Fenvessy and Schwab, a general management consulting and executive recruiting firm. In 1979, Fenvessy and Schwab was commissioned by a group of major mining companies to conduct a worldwide study of supply and demand for mining engineers to the year 2000*. The study began at the height of the North American shortage. One major objective of the study was "to identify means by which business and educational institutions may cope with and alleviate a future shortage of mining engineering talent." The findings, however, ran directly counter to expectations. The current oversupply will not disappear with economic recovery, the study concluded. In fact, the US and Canada are facing a massive oversupply that will probably last until the end of the century, unless enrollments in schools are reduced. Study Method Fenvessy and Schwab's conclusions are based on supply and demand models for mining engineers that it developed in the course of the study. Specifically, predictions for the supply of mining engineers are based on a survey of the 54 mining schools that account for about 90% of the world's annual output of mining engineering graduates. This survey asked for data on historical and projected number of graduates, obstacles to further expansion, changing trends in the use of mining engineers, and graduate career patterns. Fenvessy and Schwab developed three mining engineering supply scenarios from the survey data. The high case, considered unlikely for most of the industrialized world, is based on a continuation of the 1970's soaring growth rates. The middle case was established from the mining schools' own estimates of future growth in the number of graduating mining engineers. Finally, a "low growth" case for the US and Canada assumed that the number of graduating engineers will remain at current levels. Mining engineering demand was forecast using a complex model based on the demand for 50 major minerals. Formulas were

Jan 9, 1983

By James J. Fallon

I'm glad this meeting is being held in New York. First, because the city is close to my home in New Jersey, only 35 minutes from Times Square ..... if I were to come to Times Square between two and three in the morning. Otherwise it takes two hours. But even more important is the fact that all of you good people from around the country and around the world will enjoy the unique experience of that warm friendly atmosphere in the greater metropolitan area, something that you won't see any place else on the face of the earth. Seriously, the greater metropolitan area has been a large part of my industrial, cultural and spiritual experience. There are many aspects of it which I find disagreeable but on net I would rather live in this area, at least for the time being, than any other area of the United States. As a consultant I find contact with financial institutions, corporate headquarters, information sources and a great many production and research facilities a valuable asset to my activity.

Jan 1, 1985

By James F. Holzbach

Although Disputes Review Boards have been used for some time, they had not received wide publicity at the time Monroe County first used one. Public owners frequently resist adopting new contracting practices. This paper discusses an owner's experience with Dispute Review Boards, from learning about them to their use on two (2) projects. The experiences of potential and actual contractor claims are compared to a claim on an earlier contract and the ensuing litigation. Suggestions for possible use for Owner-Engineer disputes and recommendations for use are provided.

Jan 1, 1995

The most important event affecting the United States coal industry in 1993 was the strike by the United Mine Workers of America (UMWA). This was a series of selective strikes, beginning with a strike against four Peabody Holding affiliates on Feb. 2, following unsuccessful contract negotiations between the UMWA and the Bituminous Coal Operators' Association (BCOA). Although that strike ended on March 3, the failure to reach a new contract agreement led to walkouts at several Midwestern mines on May 10. During the summer, the strike expanded to include mines of 13 companies in seven states including Ohio, Pennsylvania, Illinois, Indiana, Kentucky, Virginia and West Virginia. About 17,000 miners were idled during the strike. As the prospects for a settlement diminished, the Secretary of Labor appointed a federal mediator. The mediation resulted in a five-year contract. In addition to increases in wages and pensions, it was agreed that 60% of new job openings would be filled by laid off and active UMWA miners. In return, companies won the right to establish more flexible work rules and scheduling of miners. While some health care benefits were expanded, the agreement established a new health care system that was designed to reduce costs. Preliminary Energy Information Administration (EIA) data indicate that US coal production fell by 5% in 1993, to 859 Mt (947 million st) (Table 1). The strike was one of the primary causes of the decline in production. Another significant cause was a 27% decline in coal exports. Also, a very small displacement of domestic coal production resulted from a rise in coal imports.

Jan 1, 1994

By Elmer R. Drevdahl

During the last few years there has been a rapid increase in the development of the community or junior college throughout the United States, Some factors behind this development include the need for more college facilities to service the growing number of high school graduates, the desire of the public to provide some post high school education at reasonable costs, and the need to provide post high school educational opportunities not now provided by most of the universities and colleges. Many of the new community colleges provide at least three educational services including local opportunity to provide the first two years of a four year college program, two year technical-vocational programs of a terminal nature, and adult educational opportunities. The community college has the advantage of not being saddled with years of academic tradition which prevent it from changing to suit the educational needs of the community It serves. The flexibility of the community college in developing new programs, particularly in the technical areas, is going to provide industry with many of the badly needed technicians it is now unable to secure.

Jan 1, 1965

By Lee Herold Storey

Groundwater remediation is growing in occurrence in the western United States. Groundwater remediation programs are regulated by state water quality statutes. The remedial action plans implemented under these statutes may conflict with well-established existing rights to withdraw groundwater for beneficial use. This paper discusses how the states of Arizona, Colorado and New Mexico administer conflicts between the need to withdraw and remediate groundwater with the existing rights of others to withdraw groundwater for beneficial purposes.

Jan 1, 1991

By Robert A. Metz

During the past decade we have witnessed spectacular improvements in productivity of open pit mining equipment. Thousand-horsepower engines, 200-ton trucks and 15-yard electric shovels, which such a short time ago were just dreams on a drawing board, are now realities. More productive equipment and metal shortages have encouraged increased production at existing mines and the development of new larger tonnage operations. Operators and engineers have been able to employ computers and various other types of automation to "stay on top of things". The mine geologist, however, is merely faced with a bigger and more rapidly changing pit to pick in. Keeping geologic information current in these mines presents entirely new problems to mine geological staffs. To obtain adequate geologic information on the developing orebody requires enlargement of the staff to share the work load or revision of methods in keeping with the times. The former has the disadvantage of loss of the comprehensive knowledge of the pit that a chief geologist likes to have, not to mention management's usual lack of enthusiasm for force increases.

Jan 1, 1970

By Benjamin K. Pocock

When considering alternative equipment choices in mill or process flowsheets, it is important to determine both capital and operating costs of such equipment as well as other possible savings related to downstream operations. This paper presents a few case studies and shows cursory guidelines for the selection of equipment for new installations or in the retrofitting of existing plants. Based upon recent plant experience, suggestions are given to improve the operation of clarifiers, thickeners and vacuum filters.

Jan 1, 1986

By Stephen R. Brown

Current conditions in the gold market demand that mine and plant operators make budgeted production targets at the lowest possible unit costs. For those companies bringing new gold pro­duction capacity on-line, achieving budgeted production levels as quickly as possible after start-up is vitally important to mini­mize unit costs and to begin a positive cash flow. Whether the objective is to simply improve unit costs or successfully start-up a new, complex plant, success will be strongly influenced by the skill levels of the operators and supervisors. The only way to assure return on plant investment, and to survive during depressed metal prices, is to ensure that plant operators have the knowledge to effectively run the plant. Technology available in computer-based, multimedia training systems, including: inter­active animation, videos, voice-overs, schematics, and text can now be used to train operators at their own pace using plant-spe­cific information. Additionally, it has been shown that learning through multimedia provides a higher degree of long term reten­tion than more traditional learning methods.

Jan 1, 1998

By Frederik P. Agterberg

Mineral exploration consists of the acquisition of data and their interpretation to ascertain the presence or absence of uncertain events. In general, the amount of uncertainty decreases during exploration when targets become increasingly well defined. Decisions on further exploration and whether or not mining should be commenced are based on new information using both objective facts and subjective reasoning. Computers play an important role during all stages of exploration. Three recent books (References 1-3) on decision-making in exploration and mineral-resources evaluation provide additional background supplementing the papers in this volume and articles in scientific journals or other conference proceedings (e.g., References 4 and 5) dealing with the subject. Other new developments to be considered are that microcomputers are becoming increasingly important in the earth sciences (Reference 6), and so are applications of artificial intelligence (Reference 7). Microcomputer- based technology allows rapid communication between field parties and main office. Expert systems are becoming increasingly sophisticated aids for mineral exploration an can now contain objective rules based on statistical theory (Reference 8).

Jan 1, 1989

By Terence G. McCusker, Bruno Dietl

The only previous attempt to use a tunnel boring machine in the rock formations encountered in New York City was unsuccessful. However, technology has been developed since then which made a new attempt a practical proposition. Nine thousand feet each of 8'6" and 11'0" diameter tunnels were driven in Manhattan schist using Jarva TBM's together with 1100 ft. of the smaller diameter driven conventionally in Inwood marble and earth. (1) The selection of tunneling method was largely based on the need to avoid community reaction and hazardous tunneling conditions where the larger diameter tunnel passed beneath residential structures in poor condition in seamy and blocky rock. Experimentation with cutters and cutter mountings indicate that good cutter life and ease of change are available. It was found practical to use unusually large muck cars for an efficient muck disposal system. Conventional tunneling was successfully executed beneath a subway station whose invert was less than seven feet above the crown of the tunnel. Attempts at chemical consolidation and dewatering were unsuccessful in the earth section which was completed under compressed air.

Jan 1, 1974

By Raúl Castro, Marco Vera, Alfonso Ovalle

The underground mining evolution for block cave mines in Chile and worldwide has made important strides in the last decades. Nonetheless, reserves determination in the initial stages of these types of projects—mainly for long-term planning—is not studied in as much detail as it should be, especially regarding the impact on the final value of the enterprise. Today, the first estimation of the size of a block cave mine, typically expressed in tons, tends to determine very large footprints and ore bodies. The resulting large-scale mine is obtained by applying the marginal cut-off grade (COG) to determine reserves. Yet, in many cases, it is possible to obtain an equal or higher benefit, extracting fewer reserves in less time, with a smaller active area, which significantly reduces the project’s uncertainty. To explore scenarios obtained by applying a higher marginal COG in the initial phases of the project, the Hill of Value methodology is used to estimate the net present value (NPV) in relation to the production rate and the COG. However, the application of this methodology considers certain simplifications that generate results which are not completely satisfactory in specific cases. This paper suggests an improvement of this method to obtain more reliable results regarding determination of a COG profile that will optimize the NPVof a block-cave project. The methodology was developed and applied in a massive polymetallic deposit with zinc, lead, and silver mineralization, corresponding to a real block caving project. The methodology provides NPV results that differ by approximately 15% in comparison to the real mine plan, while also being considerably simpler and faster to calculate. In summary, the proposed methodology provides a reasonable and fast procedure to estimate higher than marginal COG that increases the NPV of block cave mine projects.

By Patrick M. James

Many in mining believe that the industry is slipping behind in public image, in public mineral education and, particularly, in mining's basic right to do business. It is critical to turn things around - to change the rules of the game soon - before mining loses any chance of recovery. In the industry's experience, there is a technique of project development and operation that can help gain ground on public opinion. Only recently has this technique had a name, and that is sustainable development. What is sustainable development? Sustainable development is broadly accepted and supported by the international business community. And significant thought and work has been devoted to the subject. Research into the topic was initially confusing because the definitions of sustainable development are written in terms the writer, and his or her constituency understands. To some, it refers to environmental protection. To others, it is about social responsibility. And to the developer, it is about economic benefit. Slowly a theme emerged from the research that seemed to be part of all the definitions. That theme has three parts. First, the development, whatever or wherever it is, must contribute economic value to the developer and the stakeholders of the development. Stakeholders in this context include employees, neighbors, residents of the surrounding area, citizens of the country, suppliers and all others affected by the development. Next, sustainable development must contribute environmental value. This means that at a very minimum it must be neutral and not cause irreparable damage. And last, and what is new for miners and most other businessmen, it must contribute real social value to the stakeholders. How to use the concept? With that three-part theme as a working definition, the mining industry must find ways to use that “the challenge is for an individual company to translate what sustainable development means for them. There is no one model..." Donald W. Gentry is president and chief executive officer of Polymet Mining and former professor emeritus of mining engineering at Colorado School of Mines. He added: "While simple to state, the concept is anything but simple to implement. Present trends indicate ... one wins the sustainable development argument by staking out the high ground early..." In other words, start using sustainable development principles at the beginning of the project. New ways of doing business The mining industry's challenge is to implement sus¬tainable development universally around the world. Paternalism as a way of doing business is dead and a new model of doing business is emerging. All types of businesses are learning to deal with the stakeholders of new developments. Mining cannot be an exception to these trends. To understand how the international mining business came to sustainable development, it is useful to look back a few years. For many North American mining engineers, there were few opportunities for foreign assignments from the 1960s to the 1980s. American companies had been asked to leave many of the Latin American countries. Africa was going through a continent-wide upheaval. The Soviet Union and China had Eastern Eu-

Jan 1, 2000

By Alfredo Valdivia, Jesus Schabib, Vojtech Gall, William Cao, Curt Cicileo, Andrew J. Thompson

"The East Side Access Project (ESA) involves the construction of geometrically complex underground structures including a large number of caverns and bifurcations. Initially conceived as dual lined structures with either traditional concrete or shotcrete final linings (SFL), construction economy, advances in concrete placement technology and scheduling among others led to a wide use of what is referred to as freeform or pneumatically applied concrete (PAC) for the construction of tunnel final linings. PAC is a method of applying concrete without using formwork, where a wet mix concrete is pneumatically installed to encase reinforcement to full lining thickness. PAC has been widely adopted at ESA well beyond initial expectations. The paper addresses the design and construction aspects of the PAC method and contrasts it to traditional SFL lining placement. The experience made provides guidance for future PAC and SFL applications. THE EAST SIDE ACCESS PROJECT AND USE OF FREEFORM CONCRETE The Long Island Rail Road (LIRR) currently transports commuters from Long Island into Manhattan, terminating at the already congested Penn Station on the west side of Manhattan. Once completed, the ESA Project will provide LIRR commuters direct access to the east side of Manhattan underneath Grand Central Terminal. The ESA Project will help alleviate the congestion at Penn Station, which currently accommodates New Jersey Transit, Amtrak, and LIRR lines; reduce travel time for LIRR passengers traveling to the east side of Manhattan and facilitate connections to the New York City Transit (NYCT) Subway System and Metro North Rail Road. The construction includes mining and lining of new tunnels and facilities under Manhattan and Queens. The tunnels run from Queen’s Sunny Side Yard through the existing 63rd St. Tunnel, underneath Manhattan’s Park Avenue until termination at 37th Street. Differing types of tunneling methods and final lining systems are being used depending on the ground conditions, geometry and size of the excavation, site constraints and functional requirements. Mining of the Queens segment of the ESA Project involved soft ground tunneling by pressurized face tunnel boring machines, cut and cover construction, and conventional tunneling. The Manhattan segment of the ESA Project involves mining in hard rock by tunnel boring machines, drill and blast, and road header."

Jan 1, 2016

By Edwin G. Johnsen

Underground mining is relatively safe today, but no technique or equipment is completely fool proof and 100% reliable. The only sure way to prevent accidental death or injury to underground workers is to remove them completely from the hazardous environment. This alternate approach to underground work is now feasible. Tunnelling and mining systems can be built that could be remotely controlled by men operating consoles in a surface control room. This concept, called a teleminer, would use recently developed remote control technology to remove man from underground work but still give him the capability to remotely operate mining and excavating equipment as if he were actually in the working area. It is appropriate to present this concept in the session "Environmental Controls" because the rationale for environmental control in underground areas can be significantly modified if man is excluded from the underground operation. The development of teleminers cannot only reduce or eliminate most of the requirements for conventional environmental control, but it can also create new and powerful techniques for rapid tunnelling and excavation. TELEMINER CONCEPT The concept of remotely controlled mining machines is neither new nor untried.(1)(2) Conventional remotely controlled mining equipment employs the standard techniques of extending the controls of the equipment to a remote console. For example, the rotary cutters on a remotely controlled tunnelling machine are started or stopped by a human operator turning a switch on the remote control console.

Jan 1, 1997