Search Documents

By W. D. Blackburn

If there is a single key to managing a mineral extraction company, it is the control of productivity. American labor costs, in general, tend to be in the range of 10%-15% of total costs. American coal mining labor costs, however, exhibit ranges of 30%-60% of total costs. Is it any wonder that the industry finds itself at a competitive disadvantage? When labor costs take as much as sixty cents of every dollar of revenue, there is little room for profitability. The American coal mining industry must set as a long range goal the reduction of labor costs to the 10%-15% range of total costs in order to be competitive.

Jan 1, 1986

By H. H. Murray

Industrial usage of clays for current and new applications will continue to grow into the next century. The rate of growth will be highest in the less developed areas of the world. Transportation costs are a significant part of the delivered price, so the location of reserves and processing facilities for kaolin, bentonite, and palygorskite (attapulgite) are reviewed relative to serving these emerging markets. New value added applications will increase in the more developed areas which will require high quality raw materials, more sophisticated processing, and rigorous quality control.

Jan 1, 1998

By Timothy J. Matthews, Ted Klemetti, Timothy J. Batchler, Daniel J. McElhinney

Unplanned tailgate collapses and difficult mining conditions in U.S. longwalls have necessitated the use of innovative tailgate support systems. Severe ground movement induced by longwall loading has caused operators to utilize secondary support systems that can match yield and strength requirements with expected ground reactions. Standing support performance requirements depend on the nature of the ground deformation behavior, and therefore require a good understanding of the interaction between the support and ground to achieve an optimum roof support system. Mining operations often employ standing support strategies that are unique to their mine. A support system that functions successfully in one situation could fail in another situation. It is important that the design and installation of the standing support systems provide the highest probability of preventing roof falls. Pumpable roof supports are currently being used to provide a safe working environment for longwall mining. A full understanding of the impact of these performance characteristics is necessary to optimize the support application and to provide a foundation for making further improvements in the support performance. Optimization of roof support applications helps to ensure the protection of mine workers by preventing roof falls due to inadequate support design. The load capacity and stiffness characteristics of a 27-in.-diameter pumpable support system was evaluated using the National Institute of Occupational Safety and Health (NIOSH) Mine Roof Simulator (MRS). Previously, tests to evaluate the performance characteristics were performed on a single pumpable support. The goal of this new research is to evaluate the performance characteristic effects of the pumpable support system and compare it to an individual pumpable test examination. This research of a pumpable support system configuration simulates the current installation practices in U.S. coal mines.

Jul 1, 2023

By John C. Nixon

In 1959, The Australasian Institute of Mining and Metallurgy (Aus. I.M.M.) was asked by the Federal Government of Australia and the State Government of South Australia to join in the formation and management of a new contract research organization which was subsequently named The Australian Mineral Development Laboratories (Arndel) ? This body was formerly the Research and Development Branch of the South Australian Department of Mines which had been set up to develop the Radium Hill uranium deposit. It had then gone into contract R&D and the State felt that it would be more appropriate for the Branch to become a separate national organization. The Aus. I.M.M. decided that a professional institute could not participate directly in Arndel and, as there was no other suitable industry group to do so, it formed the. Australian Mineral Industries Research Association Limited (AMIRA). AMIRA held its first Annual General Meeting in September 1959 when the first Council was elected and the Memorandum and Articles of Association were adopted. The initial task of AMIRA was to raise guarantees of work or cash from its members to underwrite Arndel for the first five years of operation. The Federal and State Governments also provided guarantees and Arndel commenced operations in January 1960.

Jan 1, 1977

By Takayuki Sakai, Takefumi Takuma, Lee Roesner

"70-foot deep rectangular-shaped bulkheads were built with sheet piles as launching and receiving shafts for a pipe jacking operation for new underground waterlines in a densely populated section of Los Angeles, California. The Press-in Piling Method was specified to drive 95-foot long sheets (a record for the method) to form the bulkheads for the Los Angeles Department of Water and Power’s LA-29 (DWP) Connection Modification and Pipe Jacking. The piling was chosen because of its very low noise and practically vibration-free nature since the site is surrounded by houses, an apartment complex, and existing water lines. The out front areas of the bulkheads were grouted to let the TBM go through without major ground water leaks. Hydrophilic foam grout was also injected in addition to welding steel scab plates on the inside to seal them to achieve sufficient watertightness behind a few split interlocks. BACKGROUND This project was located in the Crescent Heights area of Los Angeles which is a few miles south of Beverly Hills. The project represents the completion of the last phase of the Stone Hollywood Trunk Line. This was an 8-mile long water trunk line that averaged 60 inches in diameter and was built to improve the reliability of the DWP’s major water system. This section of the project involved driving 2 deep shafts to allow for the installation of a 350-foot-long 72-inch steel casing using microtunneling construction. See Figure 1 for the shaft locations and the tunnel alignment. The challenge for the project was that this water line would have to pass beneath the Hollyhills buried box drain (15 feet high by 20 feet wide). Further complicating the construction was the soils beneath the drain. The DWP chose to drive the tunnel at a depth of approximately 65 feet to ensure that the ground conditions were uniform and suitable for the microtunneling equipment. There were two previous attempts to construct this work which failed because of poor ground conditions and very high water levels. This third attempt was critical because the DWP could not afford to have another failure due to the fallout with the residents being impacted by the project."

Jan 1, 2016

By Clement K. Chase, J. A. Eisele, Paul D. Chamberlain, Terry Laverty, Lee Rice, Larry Sevenker, Albert G. Law, Daryl Tweeton, John Peters

"Name your poison," wrote Forbes, Jan. 3, 1983, in an article describing the plight of much of the mineral industry as it entered the new year. "To ask which (mining) segment is better these days is almost like asking which of several stones would make a better life preserver." "The scene has seldom seemed darker or apparently less promising," said the Mining Journal in June 1982. And the Northern Miner described the year as the third in a "3-year drought which has completely dried up (company) coffers." Thus, 1982 became the worst year for much of the mining industry since the Great Depression. Low prices, commodity surpluses, output reductions, layoffs, temporary and permanent closures, and financial losses made headlines as the general recession continued to hurl blows at an industry facing strong foreign competition, increased government regulations, and plummeting market demand. At fault were tight US monetary policies and the resulting high interest rates that, while forcing inflation to slow, also threw the economic wheels of the country into reverse gear. Automobile production, housing starts, consumer durable sales, and capital spending all fell dramatically. US industrial production fell about 8.5% in 1982, with the GNP dropping by 1.7%. Production Value Not a single mineral escaped this recession. According to the US Bureau of Mines, US nonfuel production value dropped for all but four out of 21 metals and 14 out of 44 nonmetals. Production quantities increased for only gold, lead, and zirconium among metals and for only six nonmetals. Total nonfuel mineral production value dropped a whopping 21% from 1981 levels, the largest decline since 1938 and the first since 1971. Production value was estimated at $20 billion. Metal commodities showed heavier losses than nonmetals-37% vs. 12%-because of their link to depressed automobile and construction industries. Prices From peaks in early 1980, prices of precious and base metals, ferrous and nonferrous metals, and virtually every mineral dropped to 30-month lows in June 1982. Gold dropped to $9.64/g ($300/oz) compared to a high of $27/g ($850/ oz). Silver was quoted below 164/g ($5/oz) versus a $1.61/g ($50/oz) high. Copper was offered at a five-year low of $1.22/kg (55.5¢/lb) compared with a high of $3.30/kg ($1.50/lb). Lead went for 53¢/kg (24¢/lb) versus $1.21 (554). Nickel begged for buyers at $4.19/kg ($1.90/lb) compared to a high price of $7.72/kg ($3.50/lb). Molybdenum was available at or below $8.82/kg ($4/lb), down from a high of $44/kg ($20/lb). Cobalt went for $11/kg ($5/lb) versus $55/kg ($25/lb). Adjusted for inflation, increased currency costs, and currency devaluation, many of these prices are the lowest reached in decades. Financial Profits & Losses Low prices severely impacted companies' earnings, turning profits into sometimes disastrous or fatal losses. Robert Norton, director of the US Bureau of Mines, noting there has been a recession in the mineral industry for years, said, "Profit rates as related to invested capital have been considerably lower (for mining) than those of other industries. Mineral industry profits have been subject to greater cyclical swings and debt equity ratios have been significantly greater than

Jan 5, 1983

By Stephen V. Thompson

Within recent years portable seismic refraction units have found their place in the industry for shallow investigations, Completely portable, relatively inexpensive and of proven accuracy, the portable refraction seismograph is an electronic tool in an electronic age. The age of electronic instrumentation has seen the development of seismic reflection and refraction equipment for deep exploration, especially in the petroleum industry. Large, expensive units, normally truck-mounted and utilizing explosives, are being used successfully for this type of sub- surface investigation. The portable seismograph utilizes the same theory for shallow work as that applied to deep refraction seismology.

Jan 1, 1964

The results of studies to ameliorate acid mine drainage by retarding the rate of oxidation of pyrite at source are discussed. In the transpassive region, pyrite oxidizes by reactive dissolution, mass transfer through the product layer and diffusion in the bulk solution. One can decrease the rate of pyrite oxidation by inhibiting either oxidation reactions or cathodic reactions. It is demonstrated in this study that some surface active reagents extend the passive region by affecting both the anodic and cathodic processes. The extension to higher potentials occurs by inhibition of the anodic dissolution process whereas to lower cathodic potentials through decrease in the rate of reduction of molecular oxygen and/or ferric ions. To retard the oxidation of pyrite by ferric ions, which is considered to be the dominant oxidant under conditions of acid mine drainage, it would be necessary to restrict mass transfer or promote complexation of ferric ions at the surface. Imidazoline based reagents were found to be most effective in meeting this goal.

Jan 1, 1994

By M. H. Col

Within the last few years, there have been numerous techno-logical advancements within material handling due, in part, to the introduction of conveying systems and mobile material handling systems to the industry. Although the traditional material handling methods are still commonly used, the introduction of conveyors to the industry has provided companies with some very efficient and economical options. These "new" systems change with the industry to accommodate rigorous demands, ease of operation, and low operating cost requirements. The number of mobile material handling systems utilized in mining operations is increasing, especially in heap leaching applications. Ten years ago, mobile material handling systems like Mobile Stacking Conveyors (MSC) were considered a novelty. There were two (2) MSC's in actual operation and only one of those in a heap leaching application. Today there are numerous proven systems operating at mine sites around the world-La Coipa, Zaldivar, Florida Canyon, Cananea, El Abra, Chuquicamata, and Radomiro Tomic. The popularity of mobile systems is due to the benefits realized by individual projects. As technology advances, so do the concepts behind mobile material handling systems. Implementing self leveling mechanisms, Programmable Logic Controllers, and Global Positioning Systems to control the equipment are just a few of the recent advances that will be discussed in this paper. We will also discuss current proven systems, and touch on what we see as some of the future advances.

Jan 1, 1998

By Erich U. Petersen

Chemical zoning studies of mineralization can be useful in guiding exploration efforts. They permit one to determine the limits of mineralization and to correlate mineralized intervals in drill holes. Fahlore minerals are well suited for zoning studies because they are common minerals found in a variety of deposits, exhibit chemical diversity, and record the chemical evolution of migrating hydrothermal fluids. Zoning information in the form of metal ratios preserved in fahlore minerals was used to determine ore body limits in the Orcopampa precious metal system, Peru, and to correlate between multiple ore horizons in a sediment hosted massive sulfide (SHMS) currently under investigation. The current generations of electron microprobes provide the most efficient, accurate and economic way to analyze the tens to hundreds of sample required to successfully describe and use zoning information at the mine scale.

Jan 1, 1991

By G. Perkins

The development of the mineral industry of Jamaica has been guided by an unwritten policy which has nevertheless been reflected in various pieces of mining legislation and by case-by-case approvals of incentive packages for non-bauxite minerals. An effort has now been made to bring together in one minerals policy document, all the policy elements that have guided our laws and actions thus far and to upgrade the final version to meet the challenges of the next century. In this regard, industrial minerals will be placed on a more equal footing with bauxite, especially in terms of investment incentives.

Jan 1, 1998

By F. L. Pierson

Since the discovery of 'potash in the Carlsbad area in 1926 and the start of mining operations in 1931, "first mining," operations have been carried on. This is a room and pillar system in which approximately 62% of the total ore is removed. Or the basis of ore reserves and rates of extraction, the life of the mine in the early; days was estimated to be well over 50 years, however, even with an increase by additional ore reserves, it became increasingly apparent that the life of the mine was being shortened considerably by increased production. Further cause for the shortening of mine life was due to the exceptionally weak back over the northeast quadrant of the main orebody which had .caved in on first mining up to a height of 8 feet. Thus, in 1953 the decision was' made to begin pillar pulling, also called, second mining or final mining, and in December of 1953 this program was started after much discussion.

Jan 1, 1965

By Markus Thewes, Mario Galli

"INTRODUCTIONProject-related studies showed that lab tests are a helpful tool for the planning of EPB tunneling and soil conditioning in cohesionless soils. This type of ground commonly represents the extended application range for EPB shields, which demands for a treatment with additives. Considering soil conditioning with foam, so far, approaches exist for the investigation of the foam quality and of the conditioning behavior of soils (e.g. (EFNARC GUIDELINES 2001 2003)), but not any standards for testing procedures related to soil conditioning. State-of-the-art research on the topic is and was conducted for example in Bochum (Germany) cf. (Budach 2012; Maidl 1995), in Lyon (France) cf. (Quebaud et al. 1998), in Oxford and Cambridge (Great Britain) cf. (Borghi 2006; Peña Duarte 2007), in Delft (Netherlands) cf. (Bezuijen and Schaminée 2001), in Turin (Italy) cf. (Borio 2010; Peila et al. 2013; Vinai 2006), and in Aachen (Germany) cf. (Vennekötter 2012). Additionally, applied science is reported by the tunneling practice and suppliers of conditioning agents. Although the research focus in all these and further studies varied, similar test methods and test series were applied. A standardization of essential properties and testing methods (setup and procedures) however did not take place. The results from laboratory testing can only function as index values for practice because in the studies, production and application of the conditioning agents mainly takes place under atmospheric conditions. Nevertheless, the tests enable basic understanding of feasibility as well as processes and interactions going on during soil conditioning. For recommendations for standardized and reproducible testing see (Budach 2012; Budach and Thewes 2015).The most extensive investigations on the flow behavior of soil-foam mixtures have been performed by using the slump test from concrete engineering, cf. (DIN EN 12350-2 2009-08), which originally is applied on evaluating the workability of fresh concrete. Although this test does not describe the actual flow behavior, it rather represents an index on the workability, very much experience exists with this test method. Besides others, the workability – or flow behavior – of the EPB support medium certainly is a major factor of influence on the properties of the material in the excavation chamber and thus, for effective tunneling with EPB shields, cf. (Galli and Thewes 2014). For a summary of various investigations on the workability of conditioned soils using the slump test and resulting recommended slump ranges see (Budach 2012; Vinai 2006). Thereof, slumps between 10 and 20 cm have been reported as suitable workability for EPB applications. However, there is actually not much known about the real flow behavior of soil-foam mixtures related to rheological properties such as the viscosity (?) or potential yield stresses (t0). These physical values are necessary for a realistic determination of face pressure, for the design of required torques, and for an evaluation of the material flow at different locations in the excavation chamber, in the screw conveyor or on the conveyor belt. To generate a linear pressure distribution at the tunnel face, as it is assumed a priori, a low-viscosity fluid is favorable, whereas in the screw conveyor, a high-viscous fluid is needed for a controlled pressure decrease. On the conveyor belt, yield stress plays an important role preventing deliquescence and spilling from the belt. Attempts in characterizing the actual flowing of soil-foam mixtures have so far only been made by few researchers, the application of rheometry is rare."

Jan 1, 2016

By J. P. De Carvalho, R. Dimitrakopoulos

An actor-critic reinforcement learning approach is presented to improve the production of an industrial mining complex by defining shovel allocation and adapting the short-term plan given grade-control decisions. Blasthole data updates the simulated orebody models, which are input into a stochastic grade-control method based on a spatially constrained clustering approach that minimizes the profit-loss function. These aspects are embedded in a discrete-event simulator that defines the material flow from faces to processors. A case study at a copper mining complex shows the methods’ ability to adapt to new information, improving the quality of the material feed and increasing cash flow by 23% compared to a baseline case.

Jun 25, 2023

By B. Simser, T. Butler

Glencore’s Nickel Rim South Mine, located in Sudbury, Ontario, Canada, is a primary/secondary blasthole operation with ore zones lying between 1,100 and 1,700 m below surface. One of the main benefits of the primary/secondary mining method in high stress ground is that up to 50% of the mining will take place in secondary stopes that should be in a yielded rock mass state. Every future secondary mining stope begins as a primary stope abutment pillar. As with many mines, the stress loading history and rock mass conditions can vary considerably in space and time. Safe mining practices cannot allow for an assumption that the planned secondary stopes are indeed yielded. An incorrect assumption can result in mining development and stoping taking place in high stress ground rather than the expected yielded rock mass conditions. This can result in higher levels of seismicity than expected and incorrect ground support recommendations in areas where workers could be exposed. Seismic monitoring is the mines’ premier tool to track the actual rock mass response to mining. Yielded zones have a reasonably clear seismic signature/pattern over time that is visible in the collected data. The ability to accurately locate small magnitude seismic events can help define and delineate different stages of rock mass failure. The vast majority of the seismic data recorded by the microseismic monitoring system is below moment magnitude (Mw) 0.0. Examples are provided showing how small seismic events (Mw < -1.5) can help provide feedback from the rock mass deformation that allows the ground control engineer to gain a better understanding of how the rock mass is responding to mining processes.

Apr 26, 2022

By C. W. Schultz

The distribution of material passing a screen, or a set of screens, is described by the equation [ ] where p = the probability that a single particle will pass the screen on a single presentation k = number of layers of screen cloth n = distance from head of screen expressed as number of screen openings. This model can be used to predict the performance of conventional screening operations (i.e., k = 1) as well as the so-called "statistical screening" operations. Using this technique, in which multiple identical layers of screen cloth are employed, screening can be carried out at a finer size than is possible with conventional techniques with no loss of separation efficiency.

Jan 1, 1969

By Robert A. Westman

The INRED process has been developed step by step by Boliden since 1972 at MEFOS, the Foundation for Metallurgical Research, at Lulea in Sweden. The demonstration - plant is number five in this series. The purpose of this plant, which has a nominal capacity of 60,000 tonnes per year of hot metal is to: 1) prove the process on a sufficiently large scale to provide the basis for construction of production plants, 2) test various kinds of raw materials on behalf of licensees, 3) train operators of the first production plant, 4) develop the process further for special applications.

Jan 1, 1983

By M. R. Lastra

Island Copper Mine began gold recovery Tom molybdenum sulfide concentrates in April, 1985. Plant design capacity is 20 tons of molybdenum concentrate per day. The molybdenum concentrate is produced in a conventional copper/molybdenum flotation circuit by selective copper depression. After thickening, the molybdenum concentrate is leached with cyanide solution in a series of five leaching tanks. The leached concentrate is then filtered and soluble gold values recovered on activated carbon with a six column adsorption circuit. The gold leach extraction is approximately 80 percent with a gold adsorption on activated carbon of 97 percent.

Jan 1, 1986

By A. Wang

This paper defines the elements of a basic economic model for decision-making when considering a methane drainage system for an underground coal mine. A drainage system will require significant capital and operating expenses; hence the decision to utilize drainage must be made carefully. The model outlines the basic structure of decision-making and considers the costs and benefits when the methane is marketed and when the methane is vented to the atmosphere. The effects on mine safety and the dust levels in the mine are also considered, both in a general format and as economic variables. Sources of information for executing this decision-making are provided for an actual mine decision.

Jan 1, 1997

By D. A. Meyer

The long and arduous process of bringing aggregate produced in Mexico to the Gulf Coast of the United States really began in the 1970s when the first exploratory trips were taken by Vulcan&apos;s geologists. It was not until the middle of the 1980s that all of the elements of the project seemed favorable and the largest capital investment in Vulcan&apos;s history was given the green light. The history of the project will be covered along with a discussion of the role that market forecasting played in the process. Is this the first of many or a once in a lifetime project? In July 1987, Vulcan and its joint venture partner broke ground in Mexico for a world-class limestone quarry and crushed stone production facility. This project is the largest ever undertaken by Vulcan&apos;s Construction Materials Group, with a total cost of over 200 million dollars -a cost shared equally by Vulcan and its joint venture partner, Ingenieros Civiles Associados, or ICA, a diversified Mexican company which is also the largest construction firm in Latin America.

Jan 1, 1995