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By A. F. Edwards

The Main Pass sulphur and oil deposit is located at Main Pass Block 299 in the Gulf of Mexico, 30 miles east of Venice, Louisiana, in 210 feet of water. The deposit was discovered by Freeport-McMoRan and its joint venture partners, IMC Fertilizer and Homestake Mining, in late 1988-early 1989. The sulphur deposit contains 67 million long tons of recoverable sulphur. The sulphur occurs in bio-epigenetic limestone replacing anhydrite caprock on top of a salt diapir. Recoverable reserves of 39.4 million barrels of oil and 9.1 billion cubic feet of gas are also contained in the limestone caprock and in supracap sandstone stringers.

Jan 1, 1992

By Douglas N. Kendall

There are three definite steps in the making of a mining industry in any country. These are as follows: Step A - Geological Mapping This step covers the basic geological mapping of the country at scales of 1/250, 000 up to l/50, 000. This step eliminates territory and directs the exploration teams to the areas of potential interest. Step B Prospecting This step includes all phases from detailed geology through geophysics and drilling up to the point of proving that an economic ore body exists. Step C - Mine Development This is the expensive step, involving the creation of the mine, including shaft-sinking, ore treatment plant, etc.

Jan 1, 1963

By Daniel W. Kappes

This paper examines the issue of heap leach cash flow based on some recent operational examples. After the first six months of operation, single-lift continuous heaps produce into salable bullion only 70% of the total recoverable gold stacked. This compares with "batch" heaps and lab columns which achieve 100% in two to three months. Multiple-lift heaps often experience a second cash flow depression as a result of the holdup of gold in the heap. Heap leach projects seldom fail based Oil technical pe1for111ance, but they often fail in the sense that they gmerate cash flow at a much slower rate than expected.

Jan 1, 2000

By Walter C. Labys, William A. Vogely, David O. Wood

INTRODUCTION The past decade has witnessed a literal explosion in formal modeling of energy systems and markets. This rapid development was stimulated primarily by policy issues arising from the energy price shocks of 1973- 1974 and 1979- 1980. The suddenness of this interest is illustrated by comparing the current and earlier editions of Mineral Economics. The third edition, published in 1976, includes an addendum to the section of projection and forecasting methods because, Since the foregoing chapter was written, major events in petroleum have caused an explosion in formal modeling efforts in the energy field.a In contrast, this fourth edition includes the present chapter on energy modeling, and a separate chapter on nonfuel minerals modeling. The considerable interest in formal energy models is based on the complexity of the system, in particular the interaction between technical and engineering data and designs, and economic behavior of energy producers and users. Energy is a vital component in the economic and social well-being of nations, and must increasingly be explicitly considered in developing economic growth and welfare policies. Energy models can contribute to policy development and analysis, both by improved understanding of the energy system, and of the interaction between energy markets and the economy, and as an explicit means of analyzing and comparing the implications of alternative policy actions. At their best, formal models can clarify and illuminate policy options. In this chapter we will survey the objectives, methods, and potential contributions and limitations of energy system modeling. Section 2 considers the objectives, scope, and approaches to energy system and market modeling. Methodological approaches are then discussed more formally in section 3. Our approach is to intro- duce each model type and method via relatively simple generic models, illustrating their use by a selective review of the applications literature. Section 4 shifts the focus from modeling methods to procedures for model evaluation and improving model credibility especially in policy research and analysis. We conclude with some brief remarks on directions and opportunities for future modeling research. ENERGY MODELS: OBJECTIVES, SCOPE AND APPROACHES The concept of a model usually evokes an image of a complex, computerized system of mathematical or econometric equations providing detailed information concerning the operation of the process being modeled. In fact. models may be simple or complex, formal or mental, depending upon the purposes for which the model is intended. Simple judgmental models may be most appropriate when monitoring the overall performance of a process. When more detailed information is required and/or when the model

Jan 1, 1985

By V. Vesselinov, S. Orr

"Enhanced heap leaching - Part 1: Insights" (Orr, 2002), different flow and transport phenomena that could significantly reduce leaching recovery were investigated. The combination of such understanding with advanced flow and transport modeling establishes the link between cause and effect, thereby, directing operators to optimal design and construction of new heaps. Modeling of flow and transport in heaps could also point to a unique change in application method or rate that would maximize leaching enhancement of an existing heap under existing situation and leaching history. The use of such a model is cost effective in that it can simulate multiple scenarios of alternative leaching enhancement methods. By simulating a large number of irrigation scenarios, such a model can point to the optimal and/or the most promising alternatives for a particular heap. The authors' simulations concentrate on the effects of changes in application rates and heap design on changes in flow paths and enhanced leaching recovery. Based on such simulations, an intelligent control agent, such as Multiple Resolution Decision-Support System (MRDS) (Meystel and Albus, 2002), could build a new representation of the complex heap-leaching system. And, by learning from historical data and current information, it could provide optimal management of heap leaching and heap decommissioning.

Jan 1, 2003

The problems of toxic, noxious, and explo¬sive atmospheres caused by gases and dusts are certain special environmental considerations in underground mining. Some other problems unique to underground mining are design of stable structures in the strata and their support, lighting the workings, and control of noise in confined spaces. These affect the health and safety of the workmen and deserve critical analyses. Some of the most important environmental parameters of underground mining are summarized in Table 1. The list is not exhaustive but illustrates the scope of environmental planning in underground mining. This chapter will discuss the use of computers and computer models in mine atmospheric environmental planning.

Jan 1, 1979

By Stephen Young

The continuous monitoring of free cyanide levels is an important part of gold recovery operations. Accurate and up to the moment knowledge of the free cyanide concentration can result in substantial cost savings by allowing reduced concentra­tions with lower fluctuations, while maintaining or increasing gold recovery. Reduced free cyanide levels also result in lower detoxification costs at the mill discharge which translates into further savings while meeting environmental requirements. As can be seen from the upper curve in Figure 1 (which is based on in-service measurements), without accurate monitoring and control, cyanide concentration fluctuates during the produc­tion cycle, and is maintained at a high level to err on the side of caution. The lower curve illustrates the improved control permitted by the installation of a CY ANCOR, giving a more consistent concentration over the process cycle, and safely allowing use of a lower concentration.

Jan 1, 1995

By A. P. Chaves, A. Gomes

The cyanidation and adsorption processes at Fazenda Brasileiro mine were studied with the aim of increasing hydrometallurgical recovery. Technical evaluation of the processes consisted of (i) quantitative mineralogy of ore samples collected in different points of the circuit, and (ii) comparison of plant performance in the original (designed CIP) and in the modified (current CIP/CIL) circuits. An empirical correlation between process variables and gold grades in the cyanidation tailings was established. The suggested modifications in the circuit and in the operation conditions led to an increase in gold recovery, from 91 to 93.5%. Annual revenue is expected to show an increase of approximately US$ 1 million.

Jan 1, 1998

By V. M. Torres

An empirical correlation to detennine laboratory mill grinding time has been developed. Grinding samples to 90 ± 5# below 147 micrometers was required for a flotation testwork at Companhia Vale do Rio Doce (CVRD) Research Center. The initial samples were all below 1 mm in size with different size distributions and work indices (Wi) ranging from 13 to 23 kWh/st. Grinding curves were determined for some initial samples. A correlation was developed between percent retained on 147 micrometers at a standard time and the time required to grind each sample to the required size. This correlation was then used to grind all samples, based on the preliminary grinding model. Finally, a statistical analysis with the size distribution of all samples was performed. The success of using the correlation was confirmed and an equation was determined using the data set.

Jan 1, 1996

By Jaime E. Sepúlveda

Semiautogenous grinding (SAG) operators have been realizing the very significant impact of fresh feed particle size distribution on the mill grinding capacity. In actual practice, this impact may be quite difficult to assess because of the natural process variability that may also involve- concurrently other critical factors such as ore hardness. Recognizing the limitations of the empirical approach, the current publication proposes the use of mathematical models and simulators to explore and assess the net effect of feed particle size only, independent of any other factors. The simulation analysis here reported provides a basis to claim that the size distribution of the particles being ground (simply characterized by a % - 2" or similar measurement) is one of the most relevant controlling variables of the overall mill performance, regardless of the SAG circuit configuration.

Jan 1, 2005

By Bronson Stringham

The close area! relationship of Cretaceous or later intrusive porphyries to larger hydrothermal deposits of Pb, Zn, Au, fig, Cu, Mo, Hg,, and U of similar age in the Basin Range Province, was statistically shown in a recent paper (Stringham1) During the past year this study has been expanded to cover p11 of the larger hydrothermal deposits of similar nature occurring in the entire western United States. The sandstone type uranium deposits of the Colorado Plateau and Wyoming have been excluded since considerable controversy exists regarding their origin. The close relationship between intrusives in general and hydrothermal ore deposits has long been-recognized, but the association involving intrusive porphyry only, was suggested in 1954 when Sales concluded that the formation of porphyry may be an intermediate stage of activity between the development of granitoid rock and certain types of copper deposits. However: he applied this concept to only a few copper deposits. The relationship appears to be true also for a great majority of the hydrothermal deposits of the other metals mentioned above of Cretaceous and later age, at least in the western United States. This situation then leads to the conclusion then when exploring for similar types of hydrothermal deposits of the metals considered one may feel reasonably sure that if an intrusive porphyry of considerable size is. not present he may be facing much greater risk of finding an ore body than if a prophyry were presents Since, there are many intrusive porphyritic rocks which do not seem to be associated with hydrothermal deposit, it is believed that some distinct value can come from the recognition of intrusive porphyry which might be barren as well as the intrusive prophyry which might be productive This paper deals with that problem.

Jan 1, 1960

By Gabriel Babut, Ion Matei, Roland Moraru

Several controlled recirculation systems are in operation wor1dwide. As an unconventional technique of ventilation the implementation of such a system requires particular safety conditions and a well-founded set of feasibility factors and parameters. On the other hand, many mines in Romania are facing problemms in meeting the growing ventilation demands, so that controlled air recirculation could give an answer. The present paper presents the results of the work in this field, based on a detailed theoretical approach. Parameters wich must to be taken into account were identified and analysed, numerical simulation are carried out and an experimental test-scale model is presented.

Jan 1, 1997

By Peter Halbach

Cobalt-rich ferromanganese crusts are one type of the two oxidic metallic mineral resources in the deep ocean that incorporate metals supplied and transported from both land (aerosols, continental run-off) and sea sources (oxygen-minimum zone, hydrothermal alteration of the oceanic crust). The substances directly precipitate from cold seawater under more or less oxic conditions and form thin layers (2 up to 25 cm thick) on hard substrate rocks like volcanic hyaloclastites, weathered basaltic rocks and/or carbonate-fluorapatite; in the crusts many metals therefore exist in the highest state of oxidation. Deposits of the Co-rich ferromanganese crusts are found throughout the global oceans on the flanks, terraces and summits of seamounts and submerged volcanic mountain ranges and platforms, where the ocean currents have kept the seafloor more or less free of sediment for millions of years. The process of hydrogenetic precipitation is basically an inorganic colloidal-chemical and surface-chemical mechanism. Elements in seawater may occur as dissolved hydrated ions or as inorganic as well as organic complexes which in general have either a positive or a negative surface charge depending on the pH of the respective aqueous environment. Those complexes may form hydrated colloids that interact with each other and with other dissolved hydrous metal ions. Hydrated cations such as Co, Ni, Zn, Sn are, for example, attracted by the negatively charged surfaces of colloidal hydrous Mn-oxide particles, whereas hydrated anions (e.g. oxyanions) and elements forming larger complexes with low-charge densities (e.g. U, As, Th, Hf, REE) are attracted by the slightly positively charged hydrous Fe oxihydroxide particles.

Jan 1, 2008

By P. Schilizzi

The increased impact of mining subsidence in the U.S. coalfields and the recent regulatory constraints legislated by government and state agencies have provoked an intense research effort on this topic by government agencies, coal companies and academic institutions. Subsidence and horizontal strain predictions are a basic requirement if subsidence and its associated effects are to be controlled and contained within acceptable environmental levels. As a result, several such prediction techniques have been proposed or are currently under development to assist coal operators in minimizing the detrimental effects of these surface deformations. VPI&SU has been actively involved in this research effort in the past few years, with particular emphasis on the Appalachian coalfield. During the initial stages of this research a large number of subsidence case studies were collected from the literature, the coal industry and government agencies. In total, data from 32 longwall panels and 60 room and pillar panels were collected. This data bank was used to determine relationships between the basic mining and subsidence parameters, in order to allow the evaluation of the various prediction methods for the Appalachian coal region. Based on this data two subsidence prediction techniques, one based on profile functions and the other on influence functions have been developed. Profile function methods provide a tool for a fast calculation of subsidence on a line across a mine panel. Influence function methods, on the other hand, allow for a more detailed calculation of ground movements, in any mode and at any depth, on a grid or at any specific point. The limitations of the data of the collected case studies, i.e. accuracy of surveys, frequency of monitoring, lack of horizontal movement measurements, etc, led VPI&SU to the initiation of a detailed subsidence and strain monitoring program above a number of active mines, located in three major coal producing counties of Virginia. The aim of this program was to enhance the data base with accurate and complete measurements of surface movements and to allow, therefore, the refinement of the prediction techniques. This paper presents this monitoring program, discusses in detail the results obtained from three specific case studies and provides recommendations for the implementation of the field data in the general prediction methods.

Jan 1, 1986

By Meliton M. Garcia, Satya Harpalani

The volume of gases produced in major and trace amounts as a result of detonation of explosives in an underground mine was determined. The volumes of major gases (CO, CO2, NO and N02) were measured immediately following detonation, during the mucking operation, and following the removal of muck. Tests to identify and quantify the gases produced in trace amounts were performed following the detonation only. The composition of the gases produced varied significantly depending on the composition of the explosive/blasting agent. An average of 95% of the gases produced were found in the test chamber immediately following the detonation, while 2% was found in the chamber following the removal of the muck. Several compounds were identified in trace amounts. Of particular interest was the detection of benzene, toluene, butenes, ethyl benzene and naphthalene since exposure to some of these compounds, even in trace amounts, could present a serious health hazard.

Jan 1, 1987

By Evan Adams

The Ireland Mine is located some seven miles South of Moundsville West Virginia, along the bank of the Ohio River. We are mining the Pittsburgh #8 seam. This seam is approximately 60" in thickness, and is immediately overlain by some 10 feet of a conglommerate material. The roof is difficult to control, due to the fact that it frequently is composed of substances not hard enough to be held together with 6-foot roof bolts. In many cases, we must use 10-foot roof bolts, in order to get bolt anchorage in the limestone above the conglommerate. Due to the elasticity of the limestone and its tendency to bend rather than to break, we have been unable to maintain a pillar line. Thus, we have found it necessary to mine by the room and pillar system. Belt haulage is used on room entries to automatic loading stations, thence into 15-ton mine cars, controlled at the loading point by car spotters. The maximum belt length is 2,000 feet. Rail haulage to the slope-bottom dump is by 27- and 50-ton locomotives. The mine produces coal two shifts per day, with 7 production crews on each shift. Mine and machinery maintenance is performed on the Midnight shift. We handle an average of 660 tons per machine shift.

Jan 1, 1964

By David Lunt, Paul Messenger, Peter Allen

The Rawas Gold Project in Indonesia has a high silver ore with a ratio of approximately 25:1 Ag/Au. Four process flow­sheets were considered during the development phase, ie. full Merrill Crowe, CIP, CIP with zinc cementation of eluate and a hybrid Merrill Crowe - CIP circuit. The process plant was constructed using a CIP circuit with zinc cementation of eluate. Unusual aspects of the design include an elution circuit designed to strip three batches of car­bon per day and an elution column designed to operate with either upward or downward solution flow. Significant improvements implemented since starting up the plant include the use of local materials and labour for relining the mill, a change from lime to caustic soda for pH modification and the elimination of caustic soda dosing to the elution pre-soak step.

Jan 1, 1998

By E. V. Bowman

This paper is intended to deal with the material handling aspects of fine coal cleaning as applied to a recently built plaint in: southern West Virginia. This plant is processing 160 tons per hour of 1/4" x.0 coal on a two shift basis. Past experience with this very friable low volatile metallurgical coal indicated that its plastometer readings, varied directly with the size and length of time elapsing between mining' and ultimate consumption. Due to the mines location with, respect to its consumers, little could be done to decrease the time element. Studies indicated that the plastometer readings are considerably less in the minus 60 mesh range than that experienced in the plus 60 mesh sizes. Therefore, handling the coal in such a manner as to have the least amount of degradation became extremely important.

Jan 1, 1961

By D. Kelley

Due to pricing volatility and lack of availability of metals, the use of non-metallic materials of construction in metal extraction and refining processes has increased significantly in recent years Even though costs and availability of metals has improved recently, these factors are not expected to continue into the future as metal supplies once again fall short of global demand. One of the most common non-metallic materials of construction used in metal extraction and refining processes today is Fiberglass- Reinforced Plastic (FRP). These processes often require materials of construction that can resist acids and high concentrations of acid chloride salts. As shown in Table 1, FRP based on epoxy vinyl ester resin has the same chemical resistance to acid and better resistance to acid chloride salts than alloy C-276 and is superior to 2205 stainless steel in both cases.

Jan 1, 2010

By Monica Pavlik, Thomas Wildeman

Water from the Forest Queen mine adit near Silverton, Colorado drains into a natural wetland. Because the pH of the water averages 5 and the iron concentration averages 18 mg/L, it was thought that the wetland might naturally treat the water. Of most concern with respect to the aquatic environment is zinc whose concentration averages 0.60 mg/L. Starting in October 1997, the surface waters, ground waters in the peat substrate, and the sediments in the wetland were sampled and analyzed four times over the course of four months. The adit water primarily remains as surface water where Fe, minor amounts of Al, and no Zn are removed. After the adit water enters the peat, then it is found that the pH rises to 5.8-6.5 and sulfate is reduced. The removal of Zn and A1 is caused by these two changes. However, Fe in its reduced state is quite soluble and may be remobilized in the reduced environment of the peat.

Jan 1, 2000