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By J. L. Vanderbeek

The SAG milling of ores with markedly variable grinding rates presents definite process control challenges. Decisions must be made regarding the selection of the most appropriate combination of mill volumetric load level, percent solids, and mill speed for the combination of ore types being processed at the moment. An investigation was performed concerning the effects of these parameters. General results are presented.

Jan 1, 1985

By N. Moony

The benefit of gravity separation in improving total gold recovery in grinding circuits has been outlined in a significant number of papers to date. However, the use of batch centrifugal concentrators (BCC) as an industry standard to extract gold has limited the potential for maximizing gravity recoveries -particularly in coarse gold deposits. This is a reflection of the high upgrade ratios obtained by BCC's which has an inverse relationship with recoveries. Survey work in Australia has indicated that installation of the InLine Pressure Jig as an alternative to the Bee will significantly increase recoveries of gold by gravity and, accordingly, increase total gold recoveries and lower operating costs.

Jan 1, 1998

By T. E. Scartaccini

A drill recorder is a permanent data collecting instrument. In open pit blast hole drilling the application of a drill recorder is that of data collection, drilling control, and drilling education. The various drilling parameters (weight, RPM, penetration, torque, and air) have a drilling correlation which can be demonstrated and documented by a recorder graph. When the correlation is physically put to use during the process of drilling, then the recorder has become a drilling tool and is no longer just a data collecting instrument, per se. By being able to maintain accurate records and drilling control, comprehensive studies of changes both operational and technological can be made. These are based on in-progress facts and not after-the-fact logs. To determine total drilling efficiency, drilling conditions must be documented and controlled. Field operations at American Smelting and Refining Company's Mission Mine have proved that by increasing drilling control, demonstration of parameter relationships, and drill monitoring, more economic efficiency can be obtained. In comparing results obtained with recorder control and conventional control a decrease of 14 percent to 36 percent of drill footage costs were obtained. The percentage of variance is dependent upon whether drilling is milled-tooth or carbide-insert bit drilling.

Jan 1, 1970

By Jr. Schnakenberg

In 1986 the U. S. Bureau of Mines (USBM) embarked on a major research effort to develop technology that can substantially reduce worker exposure to face hazards simply by relocating the equipment operators to an area of relative safety. This reduced exposure mining system (REMS) research effort enhances the USBM ongoing health and safety research efforts to reduce and control dust and noise and to reduce accidents through training and better mining practices. This paper reports progress of the research that is developing and will demonstrate the technologies required for the computer-assisted tele-remote operation of continuous mining machines, haulage systems, and roof bolting machines.

Jan 1, 1996

By E. Turner

In a joint exercise, the European Commission, (led by DG Enterprise), the EU Member States, the various sectors of the Extractive Industry, and WWF have developed a set of Sustainable Development Indicators specific to the non-energy extractive industries. Of equal significance, a Voluntary Scheme for publicly reporting the data has been created. This paper presents these indicators at the company level and explains the role of companies and trade federations in establishing the reporting process. This has been achieved in just 18 months and the paper identifies 6 Success Factors, which have made this possible. It is believed this is the first Scheme of its kind to be put into place and to have begun operation. It is a model for co-operation between government, the NGO sector and industry. The first set of data, based on the reference year 2001, has been gathered. The SD performances of the European Minerals Industry will be publicly reported on for the first time, on the basis of these 2001 data by industry sub-sector. The Member State level Indicators will follow to complete the picture.

Jan 1, 2003

By B. K. Mishra

This paper focuses on the use of a numerical tool known as the discrete element method (DEM) to study the motion of ball charge in ball mills (14-18 ft). DEM is employed to simulate the motion of individual balls. While doing so, the effect of liner design on the grinding performance of the mill is studied. Two important factors such as the configuration of the liner and the geometry of the lifting surfaces are correlated with the overall mill performance. An attempt is made to show the effectiveness of the lifter bars in transmitting power from the mill shell to the interior of the mill with particular emphasis to large diameter mills.

Jan 1, 1992

By Roland Heersink, Charles H. Wells

This paper discusses how a mill uses off-site data hosting approach to effectively utilize an entire suite of advanced applications to optimize daily operations, without incurring the overhead of on-site systems, staff and support. Details of the solution are provided, together with a live view of actual plant operations. Security and authentication mechanisms are also outlined so that users may gain an appreciation of the actual security of the remotely hosted data. A number of Web-hosted software applications provide direct connectivity to the database offering rapid and deterministic response times to clients. A 24x7 help-desk is available to authorized users from any Internet connected device. The paper shows how mill management advantageously use wireless PDA's to view what is going on at anytime and from anywhere. It concludes with a summary of how the approach is being used to speed decision-making and capture spot market opportunities.

Jan 1, 2002

By Tom Ireland, Sumi Eratne

The approach to Risk Management during the procurement of major projects often has a significant outcome on the ultimate successful delivery of a project. The $NZ4.4B Auckland City Rail Link project is the largest and most complex transportation project yet undertaken in New Zealand. Risk management prior and during procurement was undertaken in accordance the ITIG Code of Practice for Risk Management of Tunnel Works (TCoP) and through the use of an Alliance Geotechnical Baseline report. This paper describes the measures taken during the procurement process to achieve certainty with respect to outcomes and minimise project risks whilst also achieving value for money. This included the use of cloud-based delivery of geotechnical data and 3-D geological models, reducing tendering costs and allowing a focus on risk mitigation measures during the tender rather than data management.

Jun 13, 2021

By Oliver W. Marsden, John O. Marsden

This paper presents the results of a hypothetical case study that evaluates the potential transition of a large copper mining and extraction operation to 90% renewable energy. The case study considers three phases to accomplish such a transition; phase I considers installation of renewable power generation at the site to meet a portion of the current electric power needs, phase II considers conversion of diesel combustion mining equipment to electric equipment, and phase III considers implementation of renewable energy generation coupled with energy storage systems to provide approximately 90% of the total mine site energy requirements. The paper evaluates the results in the context of a range of purchased electric power unit costs ($0.065, $0.100, and $0.135/kWh) as well as various carbon tax scenarios ($0, $5.00, and $37.30/t CO2). While the case study is hypothetical and considers a range of assumptions, it clearly identifies a pathway to potentially economically viable transitions to a renewable energy platform for mining companies. This represents an approach that mining companies can use to help to meet emissions targets, as well as social responsibility and reporting requirements.

Jun 4, 2021

By A. Noble

"Linear circuit analysis (LCA) is a fundamental tool that may be used to evaluate, design and improve the performance of mineral separation. The traditional LCA methodology provides a comparative evaluation of circuit designs purely from the unit interconnections. The quantitative approach uses the analytical circuit solution to evaluate the slope of the circuit’s partition curve at the midpoint. Since the partition slope is often associated with a separation’s general selectivity, this numeric value is used to compare and rank alternative configurations. Unfortunately, the partition curve slope only reflects the separation potential of middling material. By itself, this value does not account for the relatively high unit dollar value of pure material or the gains and losses in mass yield associated with alternative circuit configurations. Realizing the value in the LCA methodology, but respecting the limitations of the partition slope valuation, the authors have derived two new performance indicators that quantitatively address pure particle misplacement (the Partition Moment of Inertia) and circuit mass yield (the Yield Score). Together, these parameters provide a better indication of separation economics in typical mineral and coal separation systems. Since the two parameters provide independent information on circuit selectivity and circuit yield, a Pareto efficiency, multi-objective function selection approach is proposed for preliminary circuit selection.IntroductionOver the past 30 years, numerous scientific and industrial studies have proposed various mineral processing circuit design methodologies that attempt to optimize the allocation of separation resources within the processing plant. Over this period, the methodologies have undergone various transitions, including the increased inclusion of process models and computationally intensive algorithms, as well as a general shift from a purely technical solution (Lauder and McKee, 1986) to partially economic solutions (Abu-Ali and Sabour, 2003; Cisternas et al., 2014). Today, circuit design is largely driven by flowsheet simulation; however, no consistent design methodology is used across the industry.One intriguing approach for circuit evaluation is linear circuit analysis (Meloy, 1983a). This method evaluates the separation potential of the circuit solely considering the unit configuration and stream interconnections. No preliminary data other than the basic circuit configuration is required to use the approach."

Jan 1, 2015

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 Bernard E. Weichman

The oil shales in the Piceance Creek Basin of northwest Colorado occur in the Parachute Creek member of the Green River formation. The oil shales were deposited in a unique environment of deposition which caused the mineral nahcolite (NaHC03) to be precipitated within the oil shales. Post-depositional tectonics resulted in extensive fracturing of the Middle Zone of the Parachute Creek member, and to a lesser degree portions of the Lower Zone, which allowed percolating ground waters to dissolve the nahcolite in the fractured portion of the oil shale beds which is characterized by broken porous oil shale, certain beds of which have collapsed into rubble and debris. The extent and porosity of the Leach Zone aquifer is dependent upon the percentage of kerogen and nahcolite originally deposited in the oil shale. Any oil shale development program in the Piceance Creek Basin of northwest Colorado will need to be preceeded by an extensive study of the Leach Zone in order to determine the effects on a mining program.

Jan 1, 1973

By Donald E. Hendrickson

A new prinicple of side dumping front end loading for underground mucking machines has completely changed the concept of underground loading and haulage equipment arrangement both in production and development work loading. Versatility and adaptability of this type of machine permits combinations with a broad range of haulage means not possible with -conventional overhead loaders. Steel "armored" conveyors serving this type of loader are replacing conventional rail mounted car haulage to give a continuous loading operation and effect important economics of reduced manpower, faster loading rates and fewer working areas for a required production. First used in Germany this easy to control and highly efficient means of placing rock from the muck pile on or into haulage means has advanced the art of underground rock loading more in the past three years than any other advancement since the first successful small crawler mounted air powered loader was introduced in 1954. Bucket type loaders with a relative new side dump principle are gaining in popularity for underground loading. They are replacing conventional overhead loaders in present applications and becoming first choice in new ones. Primarily for hard rock development and production loading they are also widely used in production loading of coal and other soft materials. This discussion briefly traces the historical development of hard rock underground loaders to the new side dump type and its present population. In more detail various applications, loading techniques and the advantages of operation, production and economy with the side dumper in hard rock loading will be dealt with.

Jan 1, 1966

By R. A. Hill

A brief explanation of the theoretical functioning of a regenerative system followed by its application to firstly, shuttlecars and then continuous miners and its effect on performance thereof with regard to handling, production and safety.

Jan 1, 1986

By Earle Faig

Along with other transportation modes, the barge industry will be greatly effected by trends in domestic coal production. Traditionally, coal has been one of the major commodities moved by barge. Now, because of events in the international energy market, coal is finally getting the recognition it deserves as a major component of the country's energy program. Perhaps even more significantly, a series of events have caused other countries to turn to the United States as a source of coal. Although the outlook for coal demand is optimistic, it will be greatly influenced by the ability of the transportation sector to handle the additional traffic. Because of our long experience in moving large quantifies of coal, the barging industry is in an excellent position to capitalize on coal's increased popularity. A brief description of the barging industry should facilitate the discussion of coal as it relates to the barging industry. Barge companies operate on a 40.23-Mm (25 000 mile) river system which includes the East and West Coasts and the Mississippi River System. Included in the Mississippi River System are the Allegheny, Monongahela, Kanawha, Ohio, Illinois, Missouri, Tennessee, Cumberland, Arkansas, Warrior - Tombigbee and Mobile Rivers as well as some smaller tributaries. The Gulf Intracoastal Waterway, which stretches along the Gulf Coast from Brownsville, Texas to Apalachicola, Florida, is also considered part of the inland waterway system.

Jan 1, 1981

By Subhash B. Bhagwat

No economic activity would take place without human ingenuity, driven by our needs and wants. Economic activity is made possible by the energy from fossil and other energy sources, our technological hardware, the buildings and infrastructure made from materials such as metals, plastics, wood, water, and numerous industrial minerals. Industrial minerals are difficult to define; however, they generally include utilitarian minerals other than metals and fuels. Some of the industrial minerals form an exception to this categorization and, as explained elsewhere in this book, belong to more than one category because of the manner in which they are used. Industrial minerals are so numerous, and their applications so ubiquitous that they often do not receive the attention given to metals or fuels. Nevertheless, without industrial minerals, many of our most fundamental economic activities such as construction of our cities and towns, control of floods, transportation of our people, the search for minerals, the smelting of metals, and the delivery of supplies of clean water would be impossible. How then do we assess the economic importance of such a variety of materials lumped together under the general designation of industrial minerals? The price per ton or the total amount consumed do not satisfactorily explain the relative value of these materials to the economy. For example, the current price of limestone is about $5/t and the price of fluorspar is about $190/t. However, nearly 1.1 Gt of limestone, valued at about $5.5 billion, are consumed in the United States annually, compared with 590 kt of fluorspar, valued at about $1 12 million. It would not, however, be accurate to conclude that the mineral with the higher total value is always more economically important. Many other questions must be answered before making judgments of this type. These questions include how many people are employed in the production, processing, and distribution of the mineral? How is the mineral used? Is it partly or entirely imported? Where do the imports come from? How is the mineral transported? Is the mineral considered critical to national security? Is there a substitute material available in case the mineral supply is interrupted? Where would the substitute be produced? What would be the basic material from which the substitute will be produced? Even when these questions have been answered satisfactorily, the economic importance of the mineral is not completely known until the consuming sectors are studied as well. For example, even though the manufacture of fighter aircraft is vital to the national security, it employs only a fraction of the number of people employed in the housing and construction industry or the automobile industry or the appliance industry. Mineral commodities consumed in these latter sectors of the economy are more significant than those consumed in the production of fighter aircraft, because nearly two-thirds of the Gross Domestic Product (GDP) depends on the purchasing power of individual consumers. In comparison, the entire defense budget accounts for only 6% of the GDP. There is no easy way to present the importance of industrial minerals to the US economy because most minerals have diverse applications and products made from industrial minerals often con- tribute to the production of other goods and services. One way of highlighting the value of a mineral would be to relate it to the GDP reported by categories such as construction, machinery, stone, clay and glass products, electrical and electronic equipment, paper and allied products, and chemicals and allied products. These GDP categories represent industries fundamental to the economy totaling $644 billion, or about 12% of the GDP in 1990. However, these categories are not convenient for discussion of the many minerals that are used in our complex economy. In a general way, minerals are the 5% of our economy that make the other 95% possible. This chapter, therefore, discusses a selected few industrial minerals to illustrate their importance to various sectors of the economy.

Jan 1, 1994

By Mauricio Brücher, Juan Camus

This article deals with open pit mine planning and a computer technology known as Direct Block Scheduling, or “DBS”. This is an emerging technology for modeling mine exploitation strategies using mixed-integer linear programming. This technique has proved to yield stronger economic results compared to the Lerchs-Grossmann (“LG”) algorithm currently used at the beginning of the mine planning process. The article briefly describes the shortcomings of current practice; then, this delves into the superior results obtained by DBS technology compared to current practice. Finally, the article argues that results achieve so far by DBS could be enhanced even further. To do this, the framework to apply this emerging technology, which is also used in current practice, should be modified to better exploit the capabilities of DBS technology. To better understand this change, an illustrated case study is presented at the end of the article.

Jun 25, 2023

By D. A. Huggins

Column flotation is finding increasing use in the flotation of copper, molybdenum and other heavy metals and coal. Columns have proven operational, cost and metallurgical advantages which caused us to investigate their use in the proposed Escondida flowsheet. A comparative pilot plant test with 35 tons of ore showed that one column can replace three stages of cleaning and result in a significantly higher concentrate grade with no loss in recovery.

Jan 1, 1987

By V. Svalbonas

The process of grinding mill quality assurance brings with it associated truths and myths. When the mill quality assurance process took its first great steps forward in the late 1970s and early 1980s, they were in response to the conditions existing, in our industry, at those times. In the late 1990s, we are faced with different conditions, and problems, and need fresh solutions. Yet the system developed for the early 1980s has produced no new approaches for the late 1990s, becoming instead more hardened and entrenched. This lack of development and actual resistance to research is now costing the industry significant amounts of money in late start-ups and useless scrap loss.

Jan 1, 1999

By W. G. Pariseau

Conventional barrier pillars in underground coal mines are intended to protect mains and sub-main entries for relatively long periods of time. Inter-panel barrier pillars that may be used in especially deep coal mines, say, below 800 m (2,400 ft), are intended to protect longwall panel faces and adjacent panel entries for the life of nearby panels. Barrier pillar failures have serious consequences, especially when failure is sudden and catastrophic. Design of barrier pillars is thus of considerable importance to safety and efficiency of operations. Locally, failure occurs at the limit to elasticity when stress tends to exceed strength. Strength of rock is stress dependent, so an analysis of stress is central to rational design of barrier pillars. There are several approaches to stress analysis for coal mine pillar design that range from the simplified but popular tributary area method including variations that use empirical definitions of the tributary area (volume) to more sophisticated numerical methods such as the boundary element method and the finite element method. Despite ease of use, empirical methods are limited and always suspect when applied to conditions beyond their scope of definition, while boundary element methods do not generally include pillars in the solution domain. The finite element method is not so restricted and thus is a natural choice for conventional and inter-panel barrier pillar safety analyses. Caving of roof strata certainly affects the distribution of stress about longwall faces and nearby barrier pillars. Conventional wisdom that considers roof strata to respond as cantilever beams indicates the longer the span the greater are loads on longwall faces and face supports. Failure of roof beams, caving, shortens spans and relieves face and support loads. The same view is applicable to barrier pillars in that long roof spans outside of barrier pillars leads to higher pillar loads than short spans. Hence, caving should be beneficial to barrier pillar safety. However, the benefit may be small depending on the extent of caving and only in the form of a slight reduction in overburden weight transmitted to the barrier pillar, especially in case of inter-panel barrier pillars. FINITE ELEMENT MODEL Finite element models for stress analysis in rock mechanics are formulated in consideration of physical laws, kinematics, and material laws. These models meet the essential requirements for equilibrium of stress, satisfy strain displacements relations, and in a general sense, relate stress to strain through material laws, often referred to as constitutive relations. The last may be complex and replete with nonlinearities. A de facto engineering material law is the elastic model in the form of Hooke?s law for linear, homogeneous materials that may be anisotropic. A limit to elasticity is imposed by strength in the form of a failure criterion or yield function that accommodates triaxial stress states. Examples used in rock mechanics are the well-known Mohr-Coulomb (MC)criterion, the popular Hoek-Brown (HB) criterion, and the Drucker-Prager (DP) criterion. The first is linear in stress, while the second is nonlinear. Both do not include any effect of the intermediate principal stress. The last is also linear in stress but includes the intermediate principal stress. All show an increase in the major principal stress at failure with confining pressure. In the UT2/3 finite element programs, the failure criterion Y is a nonlinear, anisotropic form and is also the plastic potential [1]: [YJI=+ 11NYJI=+- (1) ] where N is an exponent, usually 2, and J2 and I1 are nonlinear anisotropic forms of the second invariant of deviatoric stress and the first invariant of principal stress. The form (1) reduces to DP when N=1and isotropy prevails. When Y = 1, the limit to elasticity is reached and plastic deformation is possible. The material constants that enter (1) are all computed from unconfined compressive, tensile, and, in case of anisotropy, shear strengths. These latter strengths may be estimated from conventional laboratory test data. Of course, joints in field-scale rock masses induce different values. How different is often a matter of conjecture. For comparative studies, laboratory rock properties seem adequate. Inelastic, that is, plastic behavior occurs with strain beyond the elastic limit. Strain hardening, ideal plasticity, and strain softening are possibilities. Ideally brittle behavior with complete loss of strength is an extreme form of strain softening [2]. Caving may also be considered as strain softening with a less drastic reduction of material properties. As intact roof strata fail, fall, and form a rubble pile below, a new material is formed with greatly reduced elastic moduli and strengths, say, 1/100th of the original intact moduli and strengths. From another viewpoint, caving is simply a natural cut and fill process. Input for stress analysis by the finite element method includes: 1. Preexcavation stress state 2. Geology (stratigraphic column) 3. Structure (major faults, joint sets) 4. Elastic moduli 5. Strengths, and specific gravities of each rock type 6. Excavation sequence Output from an analysis includes distributions of: 1. Stress 2. Strain 3. Displacement 4. Local factor of safety (element fs) The last is defined as the ratio of strength to stress and in view of the failure criterion (1), is the ratio [fsJstrengthJstress=] where the numerator is the maximum possible value and the denominator is the actual value of the square root of the second invariant of deviatoric stress. This invariant is a measure of shear stress intensity but also reduces to uniaxial tensile and compressive strengths as the case may be. An fs greater than 1 indicates an elastic state of element stress; a value of 1 indicates the limit to

Jan 1, 2009