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By S. Ostap

INTRODUCTION Paradoxically, it has been found that the people who are the most aware of the origin, mineralogy and composition of bauxite are also the people who are the least aware of how bauxite composition affects its treatment by the Bayer process. These people are the exploration and mining geologists normally associated with aluminum producing companies. The purpose of this paper is to give some idea of how the concentration and physical nature of the different minerals found in bauxites affect the operation of the Bayer process used to extract their alumina content. The bauxites we will consider here will be only the tropical bauxites such as occurring in Jamaica, various countries in South America i.e. Guyana, Surinam, Brazil, African bauxites, Malaysia and in Australia. When we speak of the Bayer process, it will be the North American version of the Bayer process using low caustic concentrations and bauxite digestion temperatures varying between 130° to 250°C. TABLE 1 shows the minerals and elements of interest occurring in tropical bauxites. The minerals and elements listed in the table do not by any means represent all of those identified in bauxites. Using mass spectrographic analysis on six bauxites from different geographic locations, we managed to identify between 50-60 different elements. Fortunately, only about 13-14 of these elements possess the necessary chemical properties to be able to accumulate in caustic Bayer solutions. The remainder are either not attacked, or form insoluble reaction products with some main liquor component, i.e., hydroxide, aluminate or carbonate, or reprecipitate with alumina trihydrate during the precipitation stage.

Jan 1, 1984

By J. den Drijver, M. Opahle, R. Inderst

Safety reasons render necessary the advanced calculation of the amount of methane degassing from a longwall in the scope of the ventilation planning of mines. Today empirical methods, which are based on observations of operational procedures, are used for the calculation of the amount of methane. Despite of constant improvement those calculations are not always sufficient. In particular calculations which are based on operational facts but not proved by experience are not reliable. Most of all these calculation procedures lack physical-analytical descriptions of the procedure itself, presenting only the effects on important parameters such as the distance between seams in the roof or floor or gas pressure. Tschersich [Tschersich 961 developed an analytical model for an advanced calculation by analysing the degassing of seams in the roof and floor and the physical parameters of gasflow. This model might correct the lacks of existing procedures and improve the precision and reliability of additional calculations. The model simulates the emission record in seams of the roof and the floor. It takes into account not only a multitude of parameters such as the distance to adjacent seams and gas pressure but also the depth of seams, gas content, rank of carbonification, rock temperature, face advance rate, initial and succeeding mining and the face length. In order to comprehend and to verify those correlations we extended the model of Tschersich and programmed this enlarged model using the computer language C++. Aim of this research is to guarantee a much higher accuracy in calculating methane emission caused by mining. The improved planning is expected to result in more safety and better prevention of high methane con- tent in ventilation as well as in a better use of the capacity of the mining equipment. The application [Drijver, lnderst 961 of the ex- tended model will also be very useful in the course of research projects as it allows computer simulation, i.e. in-situ research can be extensively limited or even replaced.

Jan 1, 1997

By M. Cai

Transformation of the measured borehole deformations induced by stress relief relies on the traditional assumption that the rock is continuous and homogeneous. Systematic and quantitative tests were carried out to check the performance of devices commonly used for measuring borehole deformations within different types of discontinuous rock conditions. Test results provide a reliable basis for considering the influence of discontinuities on in situ stress measurement and for choosing the best measuring device for a given rock type and condition.

Jan 1, 1998

By Nathaniel Arbiter

In attempting to assess the contributions of Antoine Gaudin to the profession which he illuminated for almost a half-century, we will need to examine a very broad canvas. He was active in three significant areas: as a teacher; in research, both through his own endeavors and those of his students; and as a consultant to the mining industry and to the Government. Beyond these specific contributions, there was the major personal influence he had on scores of students, friends, and colleagues in the profession. If a single measure of the man's contribution is to be found, it will be the extent and direction in which he influenced the practice of his profession. To find this we should examine the state of miner- al processing when he began his activities in the 1920's, the progress which has taken place over the past half-century, and the part his activities played in this advance. However, there is a provocative and broader examination which I have chosen to make instead. This is to examine the past century in mineral processing through the lives of three men who, by common agreement, stand on the heights, both in teaching and in their contributions to industry: Robert H. Richards, Arthur F. Taggart, and the man whose memory we honor this evening, Antoine M. Gaudin. Their careers, by coincidence, cover just a century. This is also AIME's first century, and the first century of mineral industry education in the United States. In fact, mineral processing itself on any significant scale in the country encompasses only a century and a quarter. BEGINNINGS OF PRACTICE IN THE U.S. Before the 1840qs, U.S. mining, except for coal and iron ore, was on a small scale and was confined to the eastern states, with processing practically nonexistent. The 1840's saw the beginning of Michigan native copper production, including ore dressing; the 18501s, iron ore production in Minnesota; and the 18601s, lead production and processing in Missouri. But the most explosive event was the California gold rush after 1848, which not only brought tens-of-thousands of fortune hunters to the West, but also catalyzed broad mining activities and processing within the following decades. This was not only in Calif-

Jan 1, 1976

In analyzing cost performance, managers must initially consider the issue of scope. Is the analysis for a single responsibility center or multiple centers? For a single period or a number of periods? If multiple responsibility centers are being examined, how can managers compensate for differences in their sizes? Several techniques have been developed to analyze the relationships in a set of financial statements at a single point in time and the trends in these relationships over multiple periods. Cross-sectional techniques focus on the first of these, and time-series techniques look at the latter. Although this text focuses on cost performance, these methods also can be used for revenue-related analyses.

Jan 1, 1999

By Wayne R. Charley

High operating costs and environmental restrictions have combined to increase smelting costs for precious metals to a level where many mining companies cannot afford to operate. The need for a hydro-metallurgical process to produce bullion with an efficient, economical and environmentally safe method is well recognized by the industry. This paper describes the research and development program conducted by Behrent Engineering Company in its investigation of the use of an acidic solution of thiourea for the extraction of precious metals from concentrates and high-grade ores. The areas discussed are: process design parameters, health and environmental aspects and economics of the process. The scope of this paper includes the leaching process, the recovery of precious metals from pregnant solutions and the production of dore'. Thiourea leaching offers a complete alternative to smelting and cyanidization for those concentrates and ores amenable to this process.

Jan 1, 1984

By B. Whitmoyer, J. Tian, J. E. Sneckenberger, M. A. Jerabek, C. A. Chandler

A computational procedure has been developed to determine the lung volume function for the upper airways of the human respiratory system. This analytical procedure computes a person's partial lung volume from an experimental two-microphone acoustic measurement of the upper airway passages obtained through a molded tubular mouthpiece. The theoretical transfer function for the two microphone signals as well as the related acoustic impedance and reflection coefficient for the upper airways are calculated using two-channel spectrum analysis techniques. An inverse spectrum analysis scheme then converts the reflection coefficient to an impulse response from which the airway area function is extracted using an area recovery algorithm. Numerical integration of the upper airway area function yields the lung volume function for the upper airways of the human respiratory sysytem. A software program to accomplish this computation of human upper airway volumes will be described in this paper. Application of this computational procedure to the measured tracheal acoustic impedances of 15 human subjects will illustrate the program's capability toward early detection of lung dysfunction using a prototype clinical facility.

Jan 1, 1991

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 C. Zografidis

Environmental protection, economic prosperity and respect of the need for social equity promotion, constitute a prerequisite for any modern industry aiming to operate in a sustainable manner. The Natural Stone industry in Europe, a sector comprising mainly of SMEs, despite the fact that consists a dynamic extraction sector, often lucks the resources to apply novel techniques and management schemes towards achieving sustainable performance. I-STONE, an EU Integrated Project funded by the 6th Framework Programme, is aiming to contribute in the improved performance of the Natural Stone industry. A primary project objective is the re-engineering of the stone production chain, in order among others to considerably in-crease its efficiency and productivity, and minimise the amount of stone wastes disposed. The present paper, resulting from the research con-ducted on environmental management within I-STONE, is focusing on the use of sustainable indicators as a tool for the assessment of the stone industry?s performance. Based on Commission Decisions and reported studies, a list of indicators was selected and used within I-STONE, including environmental and socio-economic indicators. A set of selected environmental indicators were quantified based on operational data of a number of Greek and Portuguese quarries examined as case studies. The analysis indicated that an integrated strategy, including the application of novel operation techniques and equipment, waste minimization and systematic environmental monitoring and reporting, constitute key factors for the sustainable operation of natural stone industry.

Jan 1, 2007

By R. C. Oberth, C. F. Lee, E. M. Taylor

INTRODUCTION Underground siting of nuclear power stations is drawing increasing attention in various parts of the world. Scandinavian countries took the early lead in this field because of their experience in the design and construction of underground hydroelectric stations and industrial plants, and because they have near-surface rock formations which are ideally suited for hosting large underground caverns. The world's first underground nuclear facilities were built in Norway (Halden) and Sweden (Agesta) and were commissioned in 1959 and 1963 respectively. Figure 1 summarizes the main features of these and two other small-scale European facilities. (1-4) American utilities and regulators are also for a variety of reasons assessing the benefits and penalties of underground siting. A recent study by Sandia Laboratories (contracted by the Nuclear Regulatory Commission (NRC) focussed on identifying potential safety benefits of underground siting. (5) Although the study concluded that underground plants would have improved containment for some accidents, as well as better external protection, NRC, in assessing the overall benefits and penalties, decided not to impose mandatory underground siting for nuclear stations. In June 1976, the California Legislature enacted a law which directed the California Energy Commission (CEC) to examine the issues concerned with underground siting of

Jan 1, 1979

By Victor F. Hollister

This section includes examples of discoveries of Kuroko- and Anyoz-type massive sulfides, and shale-hosted, zinc-lead deposits, and describes exploration models for each group of case histories. Exploration or empirical models can differ from genetic models, because ore guides and controls are emphasized in exploration models. Genetic models may form the scientific basis for exploration or prospecting models, although factors that are important to the localization of ore are stressed in exploration models. The paper by Sato (abstracted herein) on Kuroko deposits can be used as a general exploration guide for that type of deposit. It is clear, however, that no unambiguous stratigraphic control for Kuroko-type ore is given in the Sato paper. The paper by MacIntyre (an excerpt herein) describing Gataga, Midway, and Windy Craggy includes most of the elements of the shale-hosted and Anyox models. Although more recent work by the Geological Survey of Canada has modified the Windy Craggy stratigraphy, the Anyox model as applied to Windy Craggy is well described in the MacIntyre (1983) paper. Discoveries of ophiolite-, Ducktown-, volcanic-associated Ni- Cu-, and Besshi-type deposits are not included in this section. Conformable massive sulfide deposits are generally assumed to be syngenetic. Sulfides in the crosscutting feeder zones, however, are classed as epigenetic. Therefore, volcanogenic massive sulfides can contain both a syngenetic and an epigenetic component. Vital to the development of the epigenetic component is a heat source that propels the convection cycle that forms both components. In all massive sulfide discoveries described in this section, it is assumed that a volcanic magma fueled the hydrothermal fluids.

Jan 1, 1991

By K. Rajamani

A mathematical model based on the pertinent fluid dynamic equations to predict the performance of the hydro cyclone has been developed which will eventually replace the empirical model. Experimental measurements of fluid velocity profiles made in a 75 mm hydrocyclone by laser Doppler velocimetry (LDV) agree well their predictions by solving the Navier-Stokes equations numerically. Particle slip velocity and particle trajectory were computed which in turn, yields separation curve of the hydrocyclone.

Jan 1, 1988

By Allen V. Reicks

Modern conveyor pulleys are welded steel structures subjected to dynamic loads. In this paper, fatigue notch and fracture mechanics methods are applied to several weld joints on typical pulley constructions. These methods are used to analyze field applications and are correlated with laboratory testing. Generalized approaches are presented which provide high confidence in pulley design with corresponding high reliability.

Jan 1, 1996

By N. E. Norman

A great deal of effort has been put forth in recent years to arrive at accurate projections of the demands for tunnels in this decade. In reviewing the statistics presented by various study groups, it appears that during the decade from 1960-69, there were some 1,335 miles of rock and soft ground construction tunnels excavated throughout the world. These statistics indicate 645 miles of rock tunnel and 689 miles of soft ground tunnel were excavated during the last decade. This is expected to increase to 3,000 miles in the 1970's according to projections made by various authorities in the field of construction tunneling. I point out the above statistics to emphasize two main points: (1) The demands for tunneling in this decade alone are staggering. (2) There is a fairly even distribution in the amount of rock tunneling and soft ground tunneling being excavated. Unfortunately, available statistics do not answer many important questions about tunneling which are of great importance to the contractor and to boring machine designers. For example, how many of the projects completed in the past decade involved both soft ground and rock tunneling? How many projects involved tunneling in conditions where both rock and soft ground were contacted at the same face. While the answers to these questions remain unanswered, I am sure most of you can think of numerous examples of projects where mixed face conditions are prevalent. Many of you are probably familiar with the Austin Crosstown Interceptor which was bid last month in Austin, Texas. Here is a project involving 57,000 feet of tunnel where limestones and clay shales are expected to be traversed. Another project, the Tonner Tunnels No. 1 and No. 2, near Los Angeles, involve some 22,000 feet of tunnel where mixed soil and rock conditions are expected. A large majority of the projected tunnels for this decade are to

Jan 1, 1997

By W. Allen Dupree, Charles D. Campbell

A field investigation was conducted by the Ventilation Division, Pittsburgh Health Technology Center (PHTC), Mine Safety and Health Administration (MSHA) to evaluate the effectiveness of a blowing face ventilation system utilizing a water sprayfan system and a single inlet flooded bed dust collector (scrubber) in controlling methane liberation in the face area while mining at brattice distances up to 12.2 meters (40 feet) from the face. The rated capacity of the scrubber was 117 m3/s (4,145 cfm) of air. Results from the investigation indicated a methane dilution capacity of 0.57 m3/s (20 cfm) with the air quantity behind the line brattice averaging 138.7 m3/s (4,900 cfm).

Jan 1, 1991

By Edward F. Fries

Computerized, real -time monitoring had its beginning in the U.S. coal industry in the early 1970's. Over the last 10 years, developments in technology have made systems available that are capable of monitoring and controlling many mine parameters that can increase safety and production. However, situations currently exist where computerized monitoring systems are not being utilized to their fullest capability. They produce reams of printed output that are not sorted in a useful format, and human operators are not able to react fast enough in emergency situations tn tile large amount of information that the systems generate. A solution is the application of an expert system as the interface with real-time monitoring. An expert system would use an extensive knowledge base and human-type reasoning ability to make decisions on optimum strategies. Expert systems have been applied successfully to problems in other industries, and could provide significant benefits to mine information management systems. The use of an expert system with real-time mine monitoring is discussed in this paper.

Jan 1, 1986

By Thomas E. McNider

Preliminary studies were conducted at Jim Walter Resources, Inc. Blue Creek No. 3 Mine to determine the influence propane operated heaters exert on the mine ventilation system when two of three intake airshafts were heated. During initial use of the heaters, it was found that change in density caused by heating a portion of the air at two of three intake shafts altered under- ground air flow changes sufficient to be considered a violation of Part 75.322 of the Federal Coal Mine Health and Safety Act of 1969 as amended by Public Law 95.164. The primary concern was to accurately define the problem in order to derive a workable solution.

Jan 1, 1980

By S. Ersayin, I. Iwasaki

The application of a magnetic field was shown to be effective in controlling iron losses in a pilot-scale cationic silica fIotation in the processing of magnetic taconite concentrates. The design of a magnetic field distribution device and batch flotation test results using a 1.42-m3 (50 cu ft) WEMCO flotation cell are reported. Major losses of iron units in froth products were in the -25-µm (-500-mesh) fraction, and the application of a magnetic field decreased the flotation of fine magnetite, thereby improving the selectivity of separation. The "as-received" sample was sufficiently magnetized, and no further benefit was gained by the magnetizing treatment. The selectivity was somewhat adversely affected by demagnetizing the sample, though its effect was minimal due to the magnetic field. The device is simple in construction, low cost and may be readily installed in existing equipment. Key words: Iron ore, Flotation, Taconite concentrates, Cationic silica flotation, Magnetic field, Flexible magnetic sheet, Magnetizing, Demagnetizing

Jan 1, 2003

By Guy G. Jr. Granger

INTRODUCTION Due to the current depressed state of the mining industry, many mining companies have been forced to operate at less than maximum capacity. This paper will describe how the AMAX Henderson Molybdenum Mine and Mill near Empire and Parshall, Colorado respectively have utilized operations scheduling and budgeting to achieve production targets at minimum operating costs The AMAX Henderson Molybdenum Mine and Mill have been operating most recently at approximately sixty percent of maximum capacity. OPERATIONS SCHEDULING Production Targets. The production targets are tons, operating days, tons per opera- ting day, head grade, recovery, and pounds of molybdenum. One specific objective of operations scheduling is to meet the production target for pounds of molybdenum. Present market conditions dictate that production be adjusted to match sales of molybdenum. Over-production and creation of molybdenum inventories is unacceptable. In summary, the product ion target for pounds of molybdenum must be met, but not exceeded. Capacity. The AMAX Henderson Mill single stage open crushing circuit capacity is 48,000 dry short tons per day. The AMAX Henderson Mill single stage semi-autogenous primary grinding mill circuit capacity is 38,000 dry short tons per day. All other AMAX Henderson Mi 11 circuits such as rougher flotation, regrind, cleaner flotation, lead leach, filtering, drying and concentrate handling are sized to accommodate the 38,000 dry short tons per day and pro- ducts from same. The tailing delivery system is designed to accommodate tailing from a 38,000 dry short tons per day operation. Constraints. One mill production scheduling constraint is that the mill operating schedule must be the same as mine production, ore haulage and crushing. There is a total crushed ore stockpi1e storage capacity of 240,000 dry short tons. This breaks down to 60,000 dry short tons of crushed ore over the three reclaim pan feeders for each of the four primary grinding mill circuits. However, there is only approximately 10,000 dry short tons of live crushed ore available over the three reclaim pan feeders for each of the four primary grinding mill circuits. Dozers must be utilized to re- claim and push the other crushed ore. Primary grinding mill throughput is

Jan 1, 1986

By D. A. Day, H. L. Marsh, P. J. Stephens, C. A. Wiggins

Lightweight cellular grout backfill behind pipe-in-tunnel has been gaining increased acceptance in the tunneling industry and has proved to be both practical and economical. Two successfully constructed projects, the Upper Scioto West Interceptor Sewer (USWIS), in Columbus, Ohio and the Benbrook Pipeline Tunnel Project in Fort Worth, Texas will be discussed. The projects represent two different but successful applications of lightweight cellular grout backfill. The USWIS placed the grout behind precast reinforced concrete pipe, in water bearing limestone, and in close proximity to residential water wells. The Benbrook Project placed grout behind 6,096 meters (20,000 feet) of steel pipe from just two locations, eliminating major surface disruption typically associated with the placement of pumped concrete.

Jan 1, 1999