Search Documents

By Robert Snow, Yingxue Yu, Howard Hanson, Patrick Zhang

One of the major current efforts by the Florida phosphate industry to reduce deep aquifer water consumption is to use 100% recycle water for flotation. This measure alone could save billions of gallons of deep well water annually. However, this also results in higher suspended solids (slimes) in flotation water, causing poor process performance particularly for amine flotation. Polymers could play a major role in allowing the industry to use high-turbidity recycle water for amine flotation without compromising its impact on the Florida economy. The enhancement of rougher flotation by polymers may also have potential. Most importantly, dramatic efficiency improvement may be realized by floating silica first. Adding polymer to flotation feed and/or water is perhaps the most economically viable way of reversing the Crago "double float" process, in order to reduce operating costs and increase phosphate recovery. This paper presents both laboratory and pilot flotation data showing the effect of different polymers on collector dosage and flotation recovery. There appeared to be an optimal range of polymer concentration beyond which the benefits do not offset the drop in phosphate recovery. The effect of poly mer is slime-level dependent. Pilot testing data show that the "Reverse Crago" process (floating silica first followed by phosphate flotation) can outperform the Crago process.

Jan 1, 1999

By G. R. Marchant

The nonferrous industry has for many years maintained monitoring stations in agricultural areas in the vicinity of smelters to collect data concerning impact of smelter emission on agricultural crop production (Thomas and Cross, 1928). However, in 1967, the United States Congress passed the Clean Air Act which was amended in 1970 (Marchant, et al., 1977). The interpretation of this act by the Environmental Protection Agency (EPA) made it necessary for the industry to install extensive real-time ambient sulfur dioxide (SO,) monitoring systems. This was only the tip of the iceberg. Since that time as a result of additional laws and agency directives, it is now necessary to monitor concentrations of a number of substances -in both air and water. And unless there is a major change in government thinking, this trend will continue during the decade of the eighties. It is difficult to estimate the full impact of these laws. Nevertheless, the impact is large and affects every person in the United States today (Anon., 1972; Rockefeller, 1971; Nelson, Yeager, and Guptill, 1973; and Anon., 1975). It prohibits the burning of trash and paper in most areas of the country. It increases the cost of transportation and the price of motor vehicles. It increases the, cost of nearly everything that is manufactured. In industries which compete in the international market, it reduces their competitive position. In some industries the environmental impact is felt on costs of goods sold in the vicinity of 25% of the total production costs. The major portion of these costs is not due to the monitoring systems but instead is due to the increased cost of production facilities, equipment, and raw materials in industries that are required to comply with environmental regulations.

Jan 1, 1979

By C. J. Roos

Ground engaging tools are used to prevent damage to the main components of earth-moving equipment. These tools consist of everything from shovel teeth to replaceable drill bits to dozer wear plates. The costs of these ?consumable? items are increasing with the costs of raw materials. This project developed a tool to be used by Newmont Mining Corporation to predict the consumption of excavator teeth. This paper presents the results of a Montana Tech research project in which an equation was developed to predict excavator teeth consumption based on production rates and rock properties.

Jan 1, 2009

By H. Nematollahi

The comminution laws The grindability of the ores or minerals is an important factor that could not be deduced from their mineralogical characteristics (Testut, 1958). Many theories have been proposed to determine the amount of work required in a comminution operation as a function of the nature of material, size and shape of the minerals before and after of comminution. The most important laws are proposed by Rittinger, Kick and Bond. According to Rittinger (1867), the work is directly proportional to the new surfaces produced during the comminution. Kick (1885) believes that the work needed to produce similar modification is proportional to the volume or mass of the material. Bond, during his 25 years of experience and research, reached to the conclusion that on the average the energy required for a known comminution is between the Rittinger's and Kick's laws (Bond, 1952). According to Bond's Third Theory, the work input is proportional to the new crack tip length produced during the particle breakage, and equals the work represented by the product minus that represented by the feed. The work input is given by the following equation: [111W = 1 Owi( FP FF(1)] where W is the The energy input to the mill, (kWh/st); F is the Feed size based on 80% passed, (µm); P is the Product size based on 80% passed, (µm); and W; is the Work Index, (kWh/st) Methods to determine the Bond Work Index Various methods have been proposed by Bond to determine the Work Index. There are some problems with the Standard Bond Grindability Test: •Requiring a special mill. •Requiring a relatively large amount of sample. •Being relatively time consuming and tedious. [ ] During the recent years, numerous attempts have been made to install faster and easier methods to determine the Work Index. A complete description of these methods is presented by Yap et al. (1982). Determining the Bond Work Index by a new size ball mill During the recent years, researchers at the University of Tehran determined the Bond Work Index, using the Anaconda simplified methods by its Denver 305- x 127-mm (12 x 5-in.) laboratory wet ball mill. The equation used to calculate the Work Index for the above mill containing 16.12 kg (35.5 lbs) of steel balls is as follow: [1 _ 1-1W;=0.54x [P [)(2)] In addition, an attempt has been made to determine the Bond Work Index similar to standard Bond ball mill procedure but by a different ball mill, smaller and in consequent portable and less laborious than the Bond ball mill. Method description Just as the standard Bond grindability test, this method is a locked-cycle dry grinding and screening process that is carried out until steady state condition is reached. Test equipment The test is conducted in a special ball mill, called the New Size Ball Mill (NSBM). The mill is scaled down with a coefficient of two-thirds from the standard Bond ball mill. It measures 200 x 200 mm (8- x 8-in.) inside (instead of 300 x 300 mm or 12 x 12 in. in Bond ball mill). Just like the Bond

Jan 1, 1995

By N. ?peh

The purpose of the paper is to present a way of assessing nonrenewable lignite resources by means of sustainability indicators. An introductory presentation of the origin and characteristics of the discussed nonrenewable natural resources is followed by the study and analysis of separate sustainability indicators. Out of many, only the ones that would directly relate to the explored coal deposit were studied. Some different viewpoints such as economic, social and environmental were assessed inside the studied landscape structure and in relation to other provincial resources using the indicators that are closely linked with the explored lignite reserves. Exploitation of coal as an underground nonrenewable natural resource, has been taking place in the ?alek valley for more than 120 years. However, about 60% of the coal will still be left underground since not all coal will have been extracted when the mine closes. According to the regional and wider national strategic goals concerning the use of natural resources and electricity production in the future, the sustainable aspect of the exploitation of the geologically well explored reserves is emphasized in the paper. Finally, we have tried to evaluate the role and the meaning of the studied underground natural resources for further sustainable development of the ?alek valley and placed stress on the most questionable spheres that should be considered preferentially.

Jan 1, 2007

By M. J. Shulman

An algorithm used by the US Coast Guard to find lost objects is utilized to optimally allocate exploration efforts during initial stages of an exploration program. Based on classical search theory, the algorithm assumes a target probability distribution function, a detection func¬tion, and a cost function. The three Junctions are analogous to delineating areas of possible mineralization, choice of exploration methods, and exploration budget. Application of the algorithm is shown for a hypothetical target distribution. Using the maximum number of field days available as the cost function, the optimal allocation of effort is shown for different exploration methods, e.g. electromagnetic survey and induced polarization. The adaption of the algorithm for the exploration process is discussed.

Jan 3, 1984

By Richard H. Gates

INTRODUCTION The U. S. Army Corps of Engineers is developing chemical explosive excavation as a construction technique for use on Civil Works projects. Large chemical charges are being used in multiple charge arrays in a variety of media and topographic situations to achieve actual construction projects. The target is the development of chemical and nuclear explosive excavation as an accepted cost-competitive construction technique. Military research using explosive excavation is also being conducted to apply this technique to military engineering for combat purposes and to military construction. The information gained from both the civil and military research is integrated into the overall development of explosive excavation. This research and development work is being conducted under the auspices of the U. S. Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory (EERL) located at Livermore, California. This organization was formed in 1962 as the Nuclear Cratering Group (NCG) to carry out the Corps of Engineers (OCE) portion of a joint agreement with the Atomic Energy Commission (AEC) to develop nuclear explosives for construction purposes. The AEC, through the Plowshare Division of the Lawrence Livermore Laboratory at Livermore, California, has been responsible for developing nuclear explosives, conducting nuclear cratering experiments, developing nuclear safety information, and developing methods for predicting the shape of the craters. The Army part of the program includes corollary chemical high-explosive cratering experiments, participation in the AEC's nuclear cratering experiments, and development of

Jan 1, 1997

By Allan J. Breitenbach

The heap leaching process has developed into a low-cost method for recovering copper, gold and silver from large and small deposits of low-grade ore. The earliest known heap leaching process with chemicals occurred in about 1752 and is attributed to Spanish miners percolating acid solutions through large heaps of oxide copper ore on the banks of the Rio Tinto (Ran Zyl, et al., 1988). In 1969, US Bureau of Mines research¬ers proposed the use of dilute alkaline cyanide solutions as a low-cost means for recovering gold values from low-grade ore containing micrometer-sized particles of gold (Miners News, 1991). The modern-day heap leaching process typically involves the percolation of leach solutions through controlled lifts of stacked, low-grade ore (crushed, aggomerated or run-of-mine) in a heap for chemical extraction of precious and base metals into solution (Fig. 1). The enriched (pregnant) solution is collected by gravity flow in lined basins, sumps and ponds for processing and recovery of the target metals (copper, gold and silver). The barren solution from the recovery facilities is recirculated to the heap, along with chemical reagents and makeup water, for containment of all process solutions in an enclosed and environmentally sound system. This involves the use of low-permeability liner systems beneath the heap leach stacks to maximize solution recovery and protect the underlying ground water (Fig. 1). This article discusses the typical heap leach liner systems currently used by mining companies in North America. The most successful heap leach pad liner systems from past precious metal operations generally include an underlying, low-permeability soil bedding material; a geomembrane liner, and an overlying protective cover fill.

Jan 1, 1994

By J. Drzymala

Particle beneficiation tests are often conducted to determine how the recovery of a key component of a particle mixture varies with overall product yield, i.e., the separation curve. The results can be misleading when an attempt is made to determine the effect of feed grade by comparing separation curves representing different feed grades or key component concentrations. This is a shortcoming of the conventional recovery versus yield diagram, which may not appear to be affected by feed concentration. To overcome this shortcoming, a method is presented for transforming and normalizing the recovery and yield coordinates so that the separation curves representing dif-ferent feed concentrations are directly comparable.

Jan 1, 2007

By Don Phelps, John Hawley, David P. Field

In recent years observational techniques of tunneling have become increasingly popular methods to facilitate complex underground infrastructure projects. The traditional design and construction management practices developed in Europe have been adapted for application in North America to suit a more restrictive management and legal culture. This paper will discuss three recent projects, the San Diego Mission Valley East Extension, Washington Dulles International Airport People Mover, and the Seattle Beacon Hill Station and Tunnels, with the objective of identifying the challenges of applying observational tunneling methods to established contractual practices in North America.

Jan 1, 2005

By L. A. Hansen, D. L. Buffington, G. H. Beckwith

This paper reviews geotechnical engineering considerations in heap leach pad design, discusses design philosophy and provides design procedures. A brief discussion of surface water hydrology ground- water protection and other design considerations are also presented. Special emphasis is placed on projects in the arid and semiarid regions of the Western United States where annual evaporation exceeds rainfall, and where good foundation conditions are usually present.

Jan 1, 1987

By R. D. Schmidt, S. E. Follin

Introduction Mineral recovery from an in situ leaching operation is determined by the often complex interaction of hydrology, mass transport, and chemical kinetics. The operating conditions of many pilot and production scale uranium leaching operations involve heterogeneities in aquifer permeability. Differences in permeability may be naturally occurring, the result of differences in main size or cementation, or they may be induced by leaching activity. Variations in permeability directly affect the fluid flow streamline pattern, fluid flux, and so also leaching geochemistry and uranium recovery. An in situ leaching hydrology model (ISL) and a mass transport-oxidation rate model (ISLGC) have been developed for use in making site specific predictions of the leachability and productive potential of heterogeneous ore deposits, and for the optimal design of leachant injection and recovery operations. The two models are linked by output and input requirements. The ISL hydrology model generates a leachant flow streamline pattern between injection and recovery points in a flow domain incorporating regions of arbitrary permeability. The ISLGC transport model describes the changing solution concentrations of uranium and oxygen and the changing mineral concentrations of uranium and pyrite resulting from convection, longitudinal dispersion, and oxidation reactions. ISL hydrology model Basic equations The differential equation for steady-state two- dimensional flow in an isotropic porous medium is

Jan 1, 1988

By D. A. Barr

The Galore Creek copper deposits lie in the Stikine River district of northwest British Columbia, a largely undeveloped region which possesses rugged mountain terrain with deeply incised valleys which support dense undergrowth. Timberline is normally at about 1300 m (4265 ft) and the higher levels contain glacial systems and large ice fields with peaks rising to 3500 m (I 1,483 ft). A location map of the Galore Creek area is given in Fig. 1. In the late 1920s, field parties under the direction of F.A. Kerr (1948) of the Geological Survey of Canada completed geological surveys of the district. Primary access for this work was provided by riverboats on the Stikine and Iskut Rivers. Kerr's party had to contend with extremely difficult travel conditions that required considerable backpacking, augmented by pack dogs in certain cases. Absence of ground control led Kerr to establish his own topographic maps. Among the geological data established was the recognition [ ] that small bodies of orthoclase porphyry in the district are often well mineralized with base metal sulfides. Copper mineralization in the upper Galore Creek valley, a tributary of Scud River which flows into the Stikine River some 80 km (50 miles) south of the small settlement of Telegraph Creek, was originally discovered during aerial reconnaissance by M. Morrison and W. Buckholz while prospecting for Hudson Bay Exploration and Development Co. Ltd. in 1955. Malachite- and azurite-stained out- crops in several parts of the Galore Creek watershed are clearly visible from distances of 500 m ( 1640 ft) or more. Claims were staked in 1956 and the copper showings were partly mapped, trenched, and investigated by shallow diamond drilling. Because of the remoteness of the area and higher priorities for expenditures elsewhere, no further work was undertaken and most of the claims were allowed to expire.

Jan 1, 1991

By Ludger Suarez-Burgoa

At the Porce III Underground Powerhouse Complex in Colombia, the observational method (Peck, 1969), was used to provide information to an underground wedge and a 2D Finite Element Method numerical models, both used to estimate the mechanical behavior of the hoisting rock mass. The observation process consisted in collecting fault events in the field and in interpreting Multiple Point Borehole Extensometers and Surface Convergence Displacement Points readings. The calibrated models were employed to predict the behavior of the pillars formed between the machine and transformer caverns. The observational method is an important activity during excavation of large openings and provides arguments to understand the rock mass mechanical behavior.

Jan 1, 2008

By Mulong Yu, Yosry A. Attia

Beneficiation of high magnesium Florida phosphates requires ultrafine grinding to liberate the dolomite (the main source of magnesium), and a separation process capable of dealing with ultrafine sizes such as selective flocculation. The objective of this study was to investigate the feasibility of separating dolomite from apatite ultrafines by selective flocculation. To achieve this objective, selective polymeric reagents to either dolomite or apatite must be first designed and synthesized. This challenging task was accomplished by carefully selecting complexing/chelating agents which are selective to either the Ca or Mg ionic sites on the minerals, and incorporating these reagents into the structure of long chain water soluble polymers to obtain either selective flocculants (with high molecular weight, MW, polymers), or selective dispersants (with low MW polymers) to either the dolomite or the apatite particles. Synthesis and testing of these polymers on individual and mixed mineral slurries, and on a sample of natural high magnesium phosphate ore, have been attempted and the results are described in the paper. The preliminary results showed encouraging signs for the feasibility of selective flocculation separation of dolomite from apatite.

Jan 1, 1993

By A. Supomo, A. Partanen, M. Mular

Although many SAG operators may agree that on-line measurement of SAG feed-size is an attractive notion, applying this information in a control strategy that recovers the investment, engineering time, and maintenance is not necessarily straightforward. The P. T. Freeport Split-Online system was justified based on the assumption that SAG feed-size could be used in a feed-forward control strategy either at the regulatory or expert system control level. Something like “as the feed size changes adjust the throughput to avoid under or overloading the mill” was envisioned. However, following installation and calibration, Cluster Analysis showed that such an approach would not be successful. However, the sensor has been successfully integrated into Freeport’s grinding control strategy other ways. It provides an input to the Kalman filter parameter estimator used in a model-based control strategy that optimizes throughput and grind. The Split sensor also provides a characteristic feed size parameter for use in an on-line work index estimator. This paper describes the calibration and installation of the Split SAG feed-size analyzer, and reviews the evolution of its use in the Freeport C3 grinding circuit control strategy.

Jan 1, 2001

By William E. Mead

The process of selecting a building site for a major structure is a complex procedure involving the consideration of a multitude of factors. The approximate geographic location for a structure is usually fixed by its intended function, though often there may be several site alternatives. Socio-economic, logistic, marketing and political factors are the primary site determinants. Also critical in site planning, however, are the environmental factors, both natural and man-made. These factors will influence the precise siting location within the limits allowed by the primary determinants and will dictate some of the basic design criteria. This paper discusses environmental factors, principally those which are natural conditions, that must be analyzed for five different groups of structures. The importance of thorough site environmental analysis based upon the principles of applied earth science is described. Significant elements to be considered in an appraisal of the geology, hydrology, seismology and meteorology are outlined.

Jan 1, 1968

By John W. Antalovich

Normally I would like to begin a talk on photogrammetry by defining the word. However modern technology has changed the science so radically that it bears little resemblance to its original definition. Photogrammetry as defined is a science of taking accurate measurements from photography. Today's photogrammetrist, in addition to working with photography, finds himself working with magnetometers, infrared scanners, radiometers, holo¬graphy, lasers, side-looking radar, digital interfaces, computers and countless other modern space age concepts. The modern photogrammetrist is a pilot, photographer, lab technician, mathematician, geologist, programmer, engineer, physicist, and cartographer. His modern instrumentation and many spheres of activity all have a role in the environmental sciences. For example, the magne¬tometer which measures the earth's magnetic fields is used to locate the earth's ore deposits. The infrared scanner captures the heat emitted from the earth to detect ground waters and thermal pollutions. To elaborate on each of his many endeavors would take volumes rather than this short paper. I have elected therefore to discuss what I feel is his most important role in the environmental sciences - that of cartographer.

Jan 1, 1970

By A. Arik

An accurate estimation of mining block grades continues to be a challenging task for ore reserve practitioners. Two of the factors that affect the accuracy of the estimates are the estimation method used and the variability of the mineralization in the deposit. The objectives of the study are twofold: Firstly, to see how different estimation methods perform on a given deposit. Secondly, to determine the impact of particular nature of the mineralization on the results. The comparison of several estimation methods for the prediction accuracy is performed using the conditional simulation results as the basis.

Jan 1, 2000

By Raymond F. Mikesell

This paper evaluates the contributions of "third parties" to surplus capacity in the world metals industries in the 1980s. Special attention is given to the role of international development agencies, such as the World Bank, that have made project loans to state mining enterprises. The paper also reviews the contributions to surplus capacity of the International Monetary Fund and evaluates the large volume of credits from commercial banks to developing countries. Although the credits to Third World countries during the 1970s facilitated the expansion of mining capacity in those countries, no one source of financing can be held responsible for a significant portion of the expansion.

Jan 1, 1989