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By I. S. Parrish

Reserve audits have increased in recent years as more companies, especially juniors, enter the ranks of producers. Corporate and individual investors are seeking corroboration of stated reserves. The reserve audit satisfies this need. An audit assures investors that the reserves, as presented, are a reasonable and accurate approximation of the quantity and grade of the economically viable material present. The reserve audit verifies that there are no fundamental errors in logic, style or the data base, and that the reserves, as given, may be used for mine planning or economic forecasting. Reserves that pass an audit may be used with confidence in preparing cash flow projections and in deriving net present value or internal rate of return on any given project. This article describes what a consultant does while performing the reserve audit. In performing an audit there are four general areas of concern that must be checked: definitions, parameters, data and procedures. In each of these, the auditor must convince himself that the reserve study has complied with governmental regulations and guidelines, professional standards and industrial practices. Any deviation from these norms must be identified and its effect upon the appropriateness of the reserves evaluated. By concluding that a reserve study passes his audit, the reviewer is stating that there are no fundamental errors in logic or style and that spot checks have revealed no substantive errors in procedure or mechanics. The responsibility for the reserves remains with the entity that compiled the original study.

Jan 1, 1990

By T. H. Combs, G. T. Lineberry

Increased productivity in the US underground coal industry has taxed pre-existing conveyor belt haulage systems. The usual remedies are costly and can disrupt production. A reduction in the belt feeder discharge rate on shuttle car sections results in more uniform loading and reduces spillage vulnerability. An investigation was made to determine the effect, if any, on shuttle car discharge time arising from lower feeder discharge rates. A five-section, underground mine is modeled, and belt spillage is introduced. The sectional feeder discharge rate is progressively lowered until spillage is precluded. At each level, the simulated spillage is measured and compared to the loss in face production. Methods for predicting the loss in face production from lower feeder discharge rates were investigated.

Jan 1, 1995

By M. Prasad, A. K. Majumder, T. C. Rao

The depletion of high-grade phosphate ores is bringing about a search for a suitable, economically viable technique that con process the abundant low-grade phosphate reserves. About 75% to 80% of the world's low-grade phosphate reserves are associated with carbonate gangue that is not amenable to treatment by the simple techniques of physical separation. The processing of sedimentary dolomitic/calcareousphosphate ore has numerous problems, including similar surface properties of the carbonate and phosphate. Two-stage reverse anionic flotation of carbonates (dolomite/calcite) has appeared to be a promising separation technique ,for the removal of carbonates from sedimentary rock phosphate. In reverse fatty-acid anionic flotation, the depression of phosphate mineral with orthophosphoric acid produces satisfactory results for calcareous as well as dolomitic phosphate ores from several locations of sedimentary origin.

Jan 1, 2000

By K. N. Han, M. C. Fuerstenau, T. B. Onlin

A mathematical model describing the concentration profile of fine particles in the axial direction in liquid fluidized beds has been developed for the removal of fine particles. A forward finite differentiation technique has been used to solve a continuity equation with a source term to predict the concentration profile and, hence the recovery as a function of time. With the aid of experimental results obtained using a fluidized bed of 3-cm diam, dimensionless parameters were identified. These parameters were used to predict the concentration profile of fine particles in fluidized beds of larger sizes. Four different sizes of fluidized beds, namely, 1.3, 3.0, 4.0, and 7.5 cm in diam, were used in this investigation. The amounts of bed particles used included 4, 8, 16, 24, 59, and 120 g, and the size of bed particles were 48x100, 100x150 and 150x200 mesh.

Jan 1, 1987

Political events during the past decade have caused businesses throughout the world to think globally. Countries once closed to free market enterprises are now open and seeking out foreign investment to help improve the well being of their populations. The mining industry has always been a global one. Today, though, the industry has become even more global. The driving forces behind this include the opening up of higher grade, lower cost mineral deposits in undeveloped and developing nations. In addition, permitting delays in the United States, coupled with stricter environmental guidelines and a general anti-mining attitude, have forced the mining industry to look outside US borders. The Mineral Economics and Management Society (MEMS) took as the theme of its seventh annual professional program "Economic Globalization of the Mining Industry." About 100 people attended the conference held in Arlington, VA in late March. Speakers included members of the investment community, academia, government and the mining industry.

Jan 1, 1998

By Zvonimir Jam?ek

In Rudarski Institut Ljubljana (RIL), i.e. Ljubljana Mining Institute, we have developed CADRIL, a smaller CAD package which purpose is to overcome the difficulties by introducing Computer Aided Design in our mines. Program CADRIL is a graphics shell for several computer applications in mining. With the basic version of CADRIL all 2D working maps for daily use can be produced. Inserting different program blocks into CADRIL we get versions MAPRIL, TAHRIL, SECRIL and so on. The main purpose of all versions is graphics design. The main and most innovative feature of CADRIL is the screen four-word command menu. Not having pull-down or tablet menus is the speciality of this program. CADRIL contains 500 achievable commands. Each of them can be composed by choosing two to four expressions stored and shown in a specific four- column menu, sorted as objects functions, parameters and modes. Thus all commands are immediately accessible. As a result of its plainness and adaptability to the present working methods of mining engineers, CADRIL quickly attained a good reputation in our mines.

Jan 1, 1992

By Nellie E. Guernsey

The Call for Papers described the session as "Top down applications; management tools for decisions, planning, investment/finance, and negotiations." In order to attract papers, and know which ones to include as well as those to reject, it was necessary to (1) define the executive suite, (2) review what had been done in previous APCOM symposia, and (3) find out what's happening now, what isn't being done, and what can be predicted. To accomplish this, especially the third task, senior managers throughout the mineral industry were generous with their time in telephone and personal interviews. Five papers were selected for presentation at the symposium and inclusion in the proceedings; the content is divided between the Executive suite in the mineral industry and those elements which apply to any Executive Suite. The Executive Suite is the top portion of the organizational tri- angle (I), those to whom the managers of functional areas such as exploration, production, finance, and marketing report. The make-up and specific activities within an executive suite reflect the organization and culture of its corporation. As there is no typical corporation, there is no typical executive suite; however, those who work within the executive suite typically do not have day to day operational responsibilities and either are, or report to, the Chief Executive Officer.

Jan 1, 1989

By Bruce Congleton

The Florida phosphate industry is a leader in environmental control, both in terms of dollars spent and significant achievements. For instance, since 1960 the phosphate industry has spent over $71 million for air pollution and control devices, including installation, research and development and maintenance. Water pollution control expenditures also total in the millions, with over $69 million spent in the same 10 year period. The industry also is a leader in water conservation measures, having spent nearly $ 18 million since 1966 for conservation devices. Since phosphate is mined by strip mining, land reclamation plays an important part in the environmental control picture. Here again, the phosphate industry has met the challenge with a voluntary program of reclamation which accounts for over 20,000 acres of land useable after mining has taken place. In terms of progress in environmental control, the industry has been able over the years to solve within the limits of technology the fluoride emission problems it once had, and is currently at work solving sulfur dioxide and particulate problems. In just the past year the industry also has been extremely successful in limiting phosphorus and nitrogen discharges into area streams. The industry continues to cooperate with state and local pollution control officials on matters of environmental control, and future plans include even closer cooperation and assistance, as well as increased expenditures.

Jan 1, 1972

By I. Iwasaki, T. Fujuita

The removal of phosphorus from steelmaking slags is essential for recycling such slags to blast furnaces for recovery of their manganese, iron, and lime contents. Phosphorus is mainly concentrated in the dicalcium silicate phase of the slags (Fujita and Iwasaki, 1988, 1989; Suito, et al., 1977). Slow-cooling of steelmaking slags in an air atmosphere increased the grain sizes of constituent minerals; however satisfactory magnetic separation results could not be attained because of the close association of a strongly magnetic ferrite phase with dicalcium silicate (Fujita and Iwasaki, 1988). Curie point of the strongly magnetic ferrite phase in the slow- cooled steelmaking slags was investigated and an attempt was made to separate the phosphorus-bearing dicalcium silicate phase in ground slag pulps heated to a temperature exceeding the Curie point. Materials and methods Slag samples, heated to its fusion temperature of 1370°C and slow-cooled in an air atmosphere, were ground dry to -90 µm (about 170mesh) in a ring grinder. The ground sample was pulped to 1% solids in distilled water using 1 kg/t sodium hexametaphosphate as a dispersant and separated in a Sala high gradient magnetic separator, Laboratory Model 10-15- 20B, using a 100-mesh expanded metal matrix and 300 m/h flow rate.

Jan 1, 1990

By P. Venkatraman, F. S. Knoll, W. S. Kow

Froth flotation is the most widely used technique for cleaning fine coal. This practice may change, however, with the development of enhanced gravity concentrators such as the Mozley Multi- Gravity Separator (MGS). The MGS is a flowing-film concentrator that utilizes centrifugal forces to improve the separation of flotation-size particles. In the present work, a pilot-scale test program was conducted to examine the effects of feed rate, feed solids content, wash water flow rate and drum rotation speed on the performance of the MGS. The test results indicate that the MGS effectively rejects high-density minerals such as pyrite, while ultrafine ash-forming minerals are removed less efficiently. A major advantage of the MGS is that high separation efficiencies can be realized without additional grinding, flotation reagents or heavy media. This article describes the working principles of the MGS and presents data obtained from recent pilot-scale test work.

Jan 1, 1995

By George H. K. Schenck

Decisions to develop deposits of calcareous materials for cement production are based largely on anticipated markets for heavy construction which utilizes concrete. The geologist should understand the fundamental factors that underlie such management decisions, so that his field work and reports will more effectively relate to the information requirements of managers in the cement industry. The paper examines the relationships that exist between exploration and development of calcareous raw materials for cement manufacture and changing factors in the marketing of cement. Continued overcapacity, improved technology, changing distribution patterns, ease of entry, economics of scale, and the nature of product demand are some of the characteristics of the cement industry that are basic to decisions regarding exploration programs and property development.

Jan 1, 1966

By A. S. Malicsi, M. D. Baker, I. Iwasaki

Fine grinding may he required for- some coals to remove sulfur and ash or to prepare coal-water slurry. Fine grinding leads to increased hall wear and its effect on the surface properties of the ground coal becomes of concern. Marked hall wear - tests were performed to study the effects of oxygen, pH, the soluble species of coal, and the addition of pyrrhotite on hall wear. The synergistic action of coal and oxygen greatly enhanced the corrosion of mild steel halls during grinding. Elec.trochemica1 measurements on a mild steel electrode in coal slurries and SEM observations of grinding hall surfaces were carried out to explore the corrosive wear mechanism.

Jan 1, 1991

By D. Koch

Bentonites and bentonite containing sealing materials are used since many years for sealing purposes in foundation, dike construction, hydraulic engineering and landfill construction, especially for encapsulation of old waste deposits In the near future compacted bentonites will be important components of multi-barrier systems for dry charge of old mines, for underground disposal of hazardous or radioactive wastes. Because of their exceptional physical, structural and chemical properties, bentonites are offering manifold possibilities to protect the environment against the negative effects of dumping grounds. Often the compliance with legal regulations for waste dumping or the isolation of contaminated areas is possible only by using bentonite containing sealing systems. The essential properties of bentonite, bentonite containing building materials and the different techniques of making horizontal technical base liners and vertical cut-off walls are explained. For horizontal technical base liners the adsorption ability, the ion exchange capacity and the swelling behavior of bentonites are important. For cut-off walls bentonite controls the rheological behavior of the slurry and is responsible for the low permeability of the hardened bentonite-cement-wall. In the multi-barrier systems of repositories for chemical or radioactive wastes compacted bentonites are considered to be favourable sealing and backfilling materials because of their high swelling capacity, their adsorption and ion-exchange ability and their plasticity in water saturated state.

Jan 1, 2005

By R. A. Bauer

Investigations of bedrock within subsided areas over abandoned coal mines in Illinois reveal very little disturbance of the bedrock. In areas that have surface subsidence of 0.3 to 1 m (1 to 3.25 ft), examination of cores from exploration drilling and investigations of the boreholes by means of closed circuit television have shown that fractures are spaced at least 0.9 to 3.6 m (3 to 12 ft) apart. They are located within a zone 6 to 15 m (20 to 50 ft) above the collapsed area in coal mines 42.6 to 112.7 m (140 to 370 ft) deep. The dip of the fractures ranges from 25° to 60°, cutting across nearly horizontal sedimentary bedding planes. The amount of fracturing found in the collapsed area decreased as the amount of soft, weak materials increased in the immediate overburden of the mine.

Jan 1, 1987

INTRODUCTION Automatic controls are devices that assist operators by performing routine tasks faster and better than they could alone. Great strides have keen taken in the development of new processes and bigger machines to improve productivity, but these developments created the need for increased protection of machinery and labor. The new production-line techniques, or continuous processes developed, resulted in routine and, frequently, demoralizing jobs. The human race is not constituted mentally to perform routine operations. Devices were needed also to gather information automatically and perform routine functions. High-capacity plants incorporating large equipment

Jan 1, 1985

By F. W. De Vries

A review as of the date of this meeting will cover the writer's perception of eachof the areas indicated in the charts. Changes in many are occurring with enough frequency that a detailed summary would be inaccurate within a few days of writing; for this reason, only an outline is appropriate for advanced preparation.

Jan 1, 1998

By S. Frimpong, N. Demirel

Overburden excavation is an integral component of the surface mine production chain. The walking dragline is the most economic production equipment for overburden excavation in strip mining. Draglines are capital intensive, and thus, investments in multiple units severely impact the economic viability of projects. The use of few dragline units results in highly concentrated production focus, which must be efficiently managed to derive the potential economic benefits. Efficient use of draglines requires a thorough knowledge of the powered functions, the 3D rotational and translational motions and machine-formation interactions within the operating environment. Dragline kinematics and dynamics are required to understand and characterize machine performance and efficiency. In order to sustain the high productivity in difficult operating conditions, the dynamics of the dragline must be modeled and analyzed based on comprehensive kinematics. This paper investigates the planar kinematics of the front-end assembly and its interactions with the formation during excavation using the “Vector Loop Analysis” formulation with comprehensive simulation modeling in MATLAB Simulink. The kinematic models are used to examine the translational, rotational and angular displacement, velocity and acceleration components of the dragline front-end assembly along defined bucket trajectories during excavation. The results are the precursors for comprehensive modeling to examine the load deformation, torque requirements and dragline stress loading profiles for improving machine health and longevity.

Jan 1, 2006

By W. C. Patrick

The Spent Fuel Test-Climax (SFT-C) was con- ducted to evaluate the feasibility of retrievable deep geologic storage of commercially generated spent nuclear-reactor fuel assemblies. One of the primary aspects of the test was to measure the thermomechanical response of the rock mass to the extensive heating of a large volume of rock. Instrumentation was emplaced to measure stress changes, relative motion of the rock mass, and tunnel closures during three year of heating from thermally decaying heat sources, followed by a six month cooldown period. The calculations reported here were performed using the best available input parameters, thermal and mechanical properties, and power levels which were directly measured or inferred from measurements made during the test. This report documents the results of these calculations and compares the results with selected measurements made during heating and cooling of the SFT-C.

Jan 1, 1986

By B. K. Mishra, R. K. Rajamani, A. D. Joshi

The liners are the most important part in the SAG mill operation. Hence, the liners and their design parameters are primarily studied to see its effect on SAG mill operations. Effective liner designs are directed to reduce downtimes, which is needed for the replacement of worn liners. There exists constant chance of improvement in the capacity of mill by studying the effect of liner design on the charge motion inside the mill. This need is satisfied by three-dimensional discrete element code "Millsoft", which uses Discrete Element Method (DEM) to analyze the motion of charge. This simulation of SAG mill keeps track of all the moving bodies like ball and rock and observes its interaction with liners and lifters. The recent work done on this software helps generating mill to more reality by putting conical wall at feed and discharge end, over the earlier flat walls. Millsoft is an effective tool to watch the change in the motion of the charge due to different types of lifter bars and different design parameters. It was concluded that by simply increasing chord length between the lifters and increasing the face angle of the lifters, capacity of the mill could be increased. On the other hand, this software can also be used to get power draft at the respective mill design.

Jan 1, 2002

By M. Sagisaka

The purpose of this study is to obtain carbon dioxide emissions by copper production systems and quantitative merit to use copper scraps in Japan. Electrolytic copper and sulphuric acid originating from the refining gas are produced in the system. In this study, the inventories such as the fuel consumption of the unit processes and the in-house electricity generation were obtained from published papers and public statistical data. The following observations were made based on the Life Cycle Assessment (LCA) method: (1) Carbon dioxide emissions from the production of electrolytic copper and sulphuric acid in the system are about 1.0 kg and 0.4 kg/kg-product respectively. The carbon dioxide emissions attributable to the transportation of copper concentrate correspond to 20% of the total emission. This emission is higher than that of zinc because the metal content in the concentrate is lower than zinc. (2) The carbon dioxide emissions from the system decrease with the recycling of copper scrap to the converting process because the consumption of copper concentrate is reduced. The reduction is estimated to be 0.18 kg-CO2/kg-Cu at the point of 0.1 kg-scrap/kg-blister Cu. This corresponds to 9% reduction for the present system. However, this recycling leads to the decrease of sulphuric acid by 450x103 tonne at the point. The recycling of scrap should be evaluated not only from the reduction of carbon dioxide emissions, but also in terms of sulphuric acid demands as well as advantage of waste management.

Jan 1, 2003