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By Brij M. Moudgil

Separation of dolomite from apatite, because of nonselective adsorption, cannot be achieved by conventional froth flotation technique. Results obtained in the present study also indicate, that this can be attributed to the depletion of the collector molecules due to complexation with the calcium and magnesium ions, dissolved from the two minerals. However, it has been established in this investigation that conditioning the material at pH 10, followed by reconditioning, without any additional collector, at pH 4, results in selective flotation of dolomite from the mixture. The recovery of apatite, in the proposed reconditioning process, is much higher than with the conventional conditioning under similar pH conditions. The mechanisms involved in the conventional conditioning, and the reconditioning process are presented.

Jan 1, 1983

By J. Trouw, W. de Bruijn, A. van Sandwijk, R. H. Heerema

Differential reduction and expansion or shrinkage of hematite under the influence of intimately associated foreign oxides may be a source of stress formation and sinter degradation during blast furnace reduction. To study specific effects, synthetically prepared hematite powder evenly doped with 1 % by weight of several elements present as oxides, was pressed into tablets and sintered at high temperature prior to reduction. Continuous theimogravimetric and dilatometric analyses were performed on the sintered tablets as these were being subjected to reduction under simulated blast furnace time/temperature/gas composition conditions up to 1183 K. These findings were coupled with observations on the microstructure of tablets removed from various stages of the reduction process. The results indicate that the degree of expansion or shrinkage of hematite during reduction is highly dependent upon impurities associated with the original material; marked differences in reduction rate and microstructure were observed as well. An important finding is that the influence of a particular additive can also strongly vary from one reduction stage to the next. The reduction behavior appears to be affected by the physical and chemical nature of the associations formed by the added elements.

Jan 1, 1990

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

INTRODUCTION The majority of ground water flow models have been developed for large computer systems. Most of these operate under a batch mode of operation, that is, the data are input with a deck of punched cards. The advent of micro- and minicomputers over the last few years opens the possibility of adapting many of these large flow programs to the smaller computers. In general, this adaptation will require more computer time to run the program, but in many cases if the small computer is in-house, the overall cost may be less than that required for a large computer. There are also a number of peripheral devices that can be used to make the data input much easier. As an example, the use of a digitizer with a finite element or finite difference mesh reduces the data input time considerably; the use of a graphics terminal for display of the mesh immediately after it is developed shows immediately whether there are errors in the location of node points. DEVELOPMENT OF AN INTERACTIVE SYSTEM The finite element program, UNSAT2, has been used over the past several years by the authors for several ground water flow problems (Bloomsburg, 1977; Bloomsburg and Wells, 1978; Zahl and Bloomsburg, 1980). In the past these programs have been run on an IBM 370/ 145 computer under the batch mode of operation. One difficulty that has been encountered has been in determining the length of time step that must be specified for operation of the program. The problem is that if the time steps are too large, the program becomes un- stable and operation ceases. If this happens in the middle of the problem, the only alternative is to reduce the length of time step and repeat the entire run. This problem has been alleviated in other pro- grams by using a subroutine that determines the time step automatically. If the solution becomes unstable, the time step is reduced automatically and that portion of the solution is repeated. With an interactive system this can be done by storing the output pressures and restarting the program with the new output pressures. Under the batch mode of operation, there is an option in UNSAT2 that allows restarting of the program from the last point of solution, but this must be specified when originally starting the program. The interactive computer system that we use currently consists of a PDP 1 1 /23 with hard disk drive, CRT terminal, plotter, graphics terminal, digitizer, and printer. The computer has 256 K bytes of core storage and the hard disk drive will accept a 5.2 M byte disk. To run a large program on a computer such as this, some overlaying must occur; that is, subroutines are stored on disk and put into core storage only when they are actually needed for running the program. UNSAT2 required very few changes to run on this computer but some changes were necessary to take advantage of the interactive capabilities of the system. One of these changes consists of the development of a program called DBUILD to build the data file for running the program. This program calls for each piece of data by prompt statement and gives instructions for using the digitizer. The data are then entered in completely unformated form. The node points must be entered in order and the coordinates are determined automatically by the digitizer. The pressure readings or initial conditions on each node point are entered through the terminal. All element information also is entered through the terminal. After DBUILD is run the mesh may be displayed immediately on the graphics scope whereupon any error in node point

Jan 1, 1986

By W. J. C. Meynink

In drier regions of the world, total containment of cyanide liquors for rainfalls less than a specific design value is often required by government regulation. For example, in Queensland total containment is required for rainfalls up to 'the 1% annual exceedence probability. In equatorial regions, where rainfall greatly exceeds evaporation, a total containment requirement is unrealistic and this is recognized by regulatory authorities. Regulatory constraints typically require that cyanide concentrations at an agreed downstream compliance point not exceed a specific value more than a specified fraction of the time. While the excessive rainfall prevents total containment, it does provide substantial dilution. This paper outlines a methodology for assessing the distribution of cyanide concentrations at a downstream compliance point in an equatorial region with limited hydrometeorological data. Consider the hypothetical mine environs depicted in Figure 1. The mine is located near the catchment divide and draws its water supply via a gravity line. Tailings from the process plant are piped to a tailings dam on a sub-catchment below the plant site. The objective is to determine the distributions of cyanide species concentrations at a compliance point just upstream of a major settlement to ensure they do not exceed regulatory limits.

Jan 1, 1991

By J. E. Brownhill

After being closed for three years, Specialty Minerals Inc.'s Port Inland limestone facility reopened in the spring of 1992 as a commercial limestone producer. In 1990, Specialty Minerals, a division of Pfizer Inc., bought Port Inland's reserves and equipment from Inland Steel because of the strategic value of the limestone for the production of precipitated calcium carbonate (PCC). Specialty Minerals' project team faced many challenges in reconstructing the Port Inland facility. Many traditions and norms had to be overturned to achieve the productivity, flexibility and cost necessary to survive in today's competitive minerals environment. Port Inland's history Inland Steel built Port Inland in 1930. It was operated as a captive source of metallurgical grade limestone for the steel industry until its closure in 1989. The facility is located in the Upper Pen¬insula of Michigan on the north edge of Lake Michigan. Operations consist of a deep water port facility with crushing, screening and stockpile storage for 453 kt (500,000 st) of finished product at the port. Ninety-nine percent of the stone is shipped by lake boat to ports within the Great Lakes. The operation is unique in that both metallurgical dolomite and limestone are produced on site.

Jan 1, 1994

By R. C. Hopper, A. A. Mathews, T. A. Lang

DESCRIPTION OF PROJECT The Straight Creek Tunnel site is located approximately sixty (60) miles west of Denver, Colorado, on Interstate Route 70 in the vicinity of Loveland Pass, in the Rocky Mountains. The ultimate project will consist of dual two-lane vehicular tunnels with a building at each portal to house mechanical ventilation equipment and other installations. The tunnels run virtually east-west on an ascending 1.64 percent grade for a distance of approximately 8,900 feet, and will pass beneath the Continental Divide at an elevation of about 11,000 feet above sea level. The maximum cover is 1,450 feet and each tunnel is approximately 48 feet wide by 50 feet high as excavated. The work now under construction consists of the North Tunnel, which initially will have two-way traffic. Ultimately it will be the west bound lanes for Interstate 70. The completion of the North Tunnel will be the fulfillment of a long felt need for better communication through the high Rocky Mountains of central Colorado and is a vital link in Interstate Route 70. The early planning for a vehicular tunnel through the Continental Divide began in the late 1930's and between November, 1941 and May, 1943 an exploratory pioneer tunnel

Jan 1, 1997

By William G. Pariseau

The purpose of this paper is to present a design procedure for the quantitative estimation of support load requirements in underground mines. Emphasis is upon the basic features of support behavior common to a large variety of support systems-bolts, timber sets, stope fill, steel arches, concrete liners and so forth. A strong reliance is placed upon fundamental principles and modern computing techniques for their quantitative implementation. Example problems illustrate the approach. Where artificial support is required, the ground in the vicinity of the face usually stands unsupported long enough for the support to be installed. At the time of installation, the load transferred to the support from the adjacent rock is essentially zero, although in some cases there may be an initial set load, for example, from timber blocking. With the passage of time and advance of the face, ground motion loads the supports. If the support system is properly designed, then the additional loading poses no threat to the safety and productivity of operations. If not, then difficulties may arise including high maintenance costs, hazardous work conditions and reduced productivity. Of course, over-design can be equally wasteful. Quantitative estimation of support loads is therefore essential to overall efficiency in mining.

Jan 1, 1975

By W. C. Morgan

This paper discusses some of the problems involved in predicting the productivity of a shovel and truck fleet in a new set of operating conditions. More specifically, it concentrates on the problems of predicting the travel times on the haul and return portions of the truck cycle under new profile conditions and the prediction of the interaction effect between the shovel and trucks at the loading point. The ability to calculate the travel times for a new road profile is not new. Additional corrections of these calculated times for expected actual operation can be made. In considering the interaction between the loader and the hauler, there are two approaches that can be taken. Probably the most accurate method of predicting the shovel-truck interaction is a simulation of the step-by-step operation considering the variation in cycle times of the shovel and trucks. This is usually called a stochastic simulation and requires input describing how these cycle times vary. However, by understanding the causes of this shovel-truck interaction it is possible to make sufficiently accurate predictions with much simpler methods. For the purpose of this discussion let us assume that the problem involves trying to predict the productivity of a single shovel-truck fleet at some future time in an existing operation. Let us also assume for simplification that the new operation to be simulated has the same loading and pit conditions and the same dumping conditions as did the existing operation. Therefore, the only difference would be the difference in the hauling profile for the new operation. The problem then becomes one of predicting the change in the travel times on the haul and return portions of the cycle, and in determining the change in interaction between the shovel and trucks with the new truck cycle times.

Jan 1, 1968

By Julia R. Budden

The role of bacterial oxidation in the mining industry is becoming more widely accepted. Western Australia has accepted the technology as a pretreatment for refractory gold concentrates more readily than most. The third of such plants has been completed at the Y ouanmi Gold Mine. This is situated approxi­mately 500 kilometres north east of Perth, in the Yilgarn mineral field. Y ouanmi concentrates are produced from underground ore and contain arsenopyrite and pyrite as the main sulphide miner­als. Refractory gold from this deposit is generally associated with the arsenopyrite portion of the material. Gold Mines of Australia Ltd ("GMA") initiated pilot scale testing at the BacTech premises in November 1993. The decision by GMA to use BacTech's technology was announced in February 1994. Design and construction commenced at this time. Bacterial growth on site was initiated in July 1994 and continuous opera­tion began in the October. Concentrate was added at 0.5 tonnes per hour and this has increased to 1 tonne per hour.

Jan 1, 1995

By Silvano Perla

Peabody Western Coal Co. operates two mines in northern Arizona. The Black Mesa and Kayenta coal mines are unique for several reasons. They both have only two customers: Southern California Edison’s Mohave generating station near Laughlin, NV and the Navajo generating station near Page, AZ. Both mines are close together. Between the two, they ship nearly 11 Mt/a (12 million stpy) of coal. Material is shipped to the power stations in two ways. This first is a 440- km-long (273-mile-long) underground slurry pipeline, the longest in the world. The second is an 11 -km-long (17-mile- long) long conveyor to four storage silos. Product is then shipped by train from the storage silos to the plant sites. Another factor makes these mines unusual. They are both situated in the middle of the 68,795km2 (17 million- acre) Navajo Reservation, home to the Navajo Nation and Hopi Tribe members. Nearly 90% of the Black Mesa and Kayentamines’ 850 employees are tribe members. Peabody Western Coal is the United States’ largest private employer of Native Americans.

Jan 1, 1995

By Allen J. Sobczak, Peter J. Peters

The five tunnel contracts of Milwaukee Northeast Side Relief Sewer System are about 80 percent complete. The tunnels are all excavated for 1.9 meter (6'-0") finish diameter sewers in a variable rock, mixed face, and glacial soil environment. Different contracts were let under two primary types of specifications, performance and prescriptive, which treated aspects of construction, such as primary ground support and groundwater control, differently. Interfacing of design and construction through field personnel allowed the needs of all parties to be met and resulted in savings in time and money to the Milwaukee Metropolitan Sewerage District (MMSD). Interfacing, cooperation and risk sharing allowed resolution of problems such as line and grade variations and potential differing site conditions. It also allowed the parties to pursue constructive changes to construction activities. Thus on one contract prescribed use of compressed air was eliminated, but migration of fines into the tunnels was stopped with filter fabric. Use of an expensive primary support system was dropped, but concern about deterioration of lagging was alleviated by use of special materials.

Jan 1, 1983

By P. T. Bissert, L. Yan, M. D. Klein

"Federal regulations require the installation of refuge alternatives (RAs) in underground coal mines. Mobile RAs have a limited ability to dissipate heat, and heat buildup can lead to a life-threatening condition as the RA internal air temperature and relative humidity increase. The National Institute for Occupational Safety and Health Office of Mine Safety and Health Research performed heat testing on a 10-person tent-type training RA and contracted ThermoAnalytics, Inc. to develop a validated thermal simulation model (TSM) of the tested RA. The TSM was used to examine the effects of the constant mine strata temperature assumption, initial mine air temperature (MAT), initial mine strata surface temperature (MSST), initial mine strata temperature at depth (MSTD), and mine strata thermal behavior on RA internal air temperature using 117 W of sensible heat input per simulated miner. For the studied RA, when the mine strata temperature was treated as a constant, the final predicted RA internal air temperature was 12.8°F lower than it was when the mine strata thermal behavior was included in the model. A 10°F increase in the initial MSST resulted in a 7.1°F increase in the final RA internal air temperature, whereas a 10°F increase in the initial MSTD yielded a 2.5°F increase in the final RA internal air temperature. INTRODUCTION Since 2008, the Mine Safety and Health Administration (MSHA) has required the installation of refuge alternatives (RAs) in underground coal mines (1). MSHA requires that RAs provide an environment with breathable air for entrapped miners for a 96-hour period. Heat buildup inside an occupied RA is a serious concern. Without a means to dissipate the heat and humidity generated by the occupants and the carbon dioxide scrubbing system, the temperature and humidity inside RAs could lead to severe discomfort or heat stress depending on the mine ambient temperature before and during occupation of the RA. NIOSH recommended an apparent temperature limit of 95°F in its 2007 report to Congress (2). In 30 CFR 7.504, MSHA has specified a maximum apparent temperature of 95°F inside an occupied RA (3). The apparent temperature is calculated using both air temperature and relative humidity (4). Calculations could be used to determine if the air within an occupied RA will reach the apparent temperature limit. In these calculations, in order to simplify the problem, the mine temperature could be assumed to remain constant. With this assumption, the effects of the mine strata thermal mass and thermal conductivity on the heat buildup in an RA are ignored. OMSHR research has shown that the mine air and strata temperatures surrounding an RA increase when subjected to the heat of an occupied RA (5). Thus, calculations performed with the assumption that the mine temperature is constant would under-predict the resulting dry-bulb temperature and apparent temperature for a given RA occupancy. The mine air temperature has been used as the basis for RA temperature calculations. However, research has not been used to confirm that the mine air temperature is the appropriate basis."

Jan 1, 2016

By John Drew Ridge

Recent work by Haas has made available information on densities and vapor pressures of solutions of differing salinities at temperatures up to 330°C. From these data it is possible to predict the behavior of volcanic exhalations of various degrees of salinity as they approach the sea floor. Particular attention is devoted to solutions of 5.0 weight per cent NaCl and 20 weight per cent NaCl, two fluids that approximate quite closely the salinities of what Roedder termed: (1) normal hydrothermal fluids and (2) fluids typical of stratiform deposits of low-temperature conditions of origin. It is apparent that solutions above 220-230°C. cannot reach a sea floor on which the depth of water is 600 feet or less in the liquid state but will boil at some appreciable depth beneath the sea floor. Such boiling would result in the precipitation of all constituents of the ore fluids of significantly lower vapor pressure than water. The principal such constituent would be salt, and no sulfide deposits, the major constituent of which is salt are known. It follows, therefore, that ore fluids probably never get close to the sea floor of shallow seas at temperatures high enough to permit boiling. Ore fluids significantly above 230°C. can reach the sea floor in the fluid state only if the depth of the sea in the area. in question is well above 600 feet, for example, solutions at temperatures of ±300°C. reach the sea floor in the liquid state only if the depth of sea water is slightly over 3000 feet. Ore fluids reaching the sea floor at such depths may be the parents of such fluids as the Red and Salton Sea brines. On the basis of these data, the Cyprus and Kuroko deposits are discussed.

Jan 1, 1973

By Ronald R. H. Cohen, Margaret W. Staub

Two pilot scale bioreactors designed to treat acid mine drainage primarily using sulfate reducing bacteria were constructed underground at the Eagle Mine Superfund site in Minturn Colorado. The project was designed to test th applicability of microbiological treatment on water with high metals concentration and to test the process in an underground environment. Objectives were, 1) to compare metal removal, pH increase, and sulfate reduction in a single stage reactor with a double stage reactor of equal volume at varying flow rates; 2) to determine where within the substrate treatment occurs· and 3) to examine volume versus surface ara as a design parameter for optimizing metal removal processes. Results from the reactors showed that the single stage reactor and double stage reactor performed equally well for the removal of Cd, Cu, Pb, Fe, Mn, and Zn. pH increased above 6.5 in both reactors. Greater than 97% of metals were removed within the first ten inches of substrate. Volume proved to be a more useful parameter for determining removal rates than area. Using volume as a design parameter rather than surface area enables PMDT systems to be constructed as packed columns rather than broad wetlands, Thus, space requirements are significantly reduced.

Jan 1, 1993

By J. E. Litz

The hydrometallurgy review did not arrive in time for publication in the May issue. 1992 was not a banner year for hydrometallurgical installations or new hydrometallurgical developments. Installation of copper solvent extraction/electrowinning circuits were under construction or began operation in Nevada (Yerrington ), Arizona (SilverBell), Chile (Copiapo and Escondida), Peru (Toquepala and Cuayone) and Australia (Girilambone). These installations will produce more than 100 kt/a (110,000 stpy) of cathode copper. Several new heap leach gold facilities using conventional technologies were announced or were put into operation. New technologies undergoing widespread testing include biological oxidation of low-grade ores in a heap leach mode and evaluation of new agglomerating agents.

Jan 1, 1993

By L. M. Gochioco

The Seismic Interactive Interpretation Workstation (IIW) integrates various sets of geophysical and geological data to form a network of information which is stored in a database. Computer models are generated from known drillhole information and later correlated with the processed seismic data. Seismic color processing adds another dimension to the interpretation process. Complex trace attributes provide better definition of subtle features not easily observed from black and white sections. Utilizing the computer workstation, the explorationist gains valuable insight and conducts more intelligent interpretation of seismic data through a more comprehensive network of data analysis.

Jan 1, 1989

Caterpillar and Fortescue Metals Group have moved forward with the delivery, installation and support of a complete Cat MineStar System at Fortescue?s Solomon iron ore mine in the Pilbara region of Western Australia. The complete technology suite was implemented for the first phase of Solomon, the 20 Mt/a (22 million stpy) Firetail manned mine, in October 2012. As part of an autonomous mining solution for phase two, the 40-Mt/a (44-million stpy) Kings Mine, eight Command for hauling Cat 793F CMD trucks were commissioned and commenced operations in the second quarter of 2013. The mine plan calls for a progressive ramp up to 45 autonomous trucks during the next several years. In addition, other Cat MineStar System capability sets, Fleet, Terrain, Detect and Health, are being used across the mobile equipment fleet, including support equipment and light vehicles. Working closely with Fortescue and its mining contractor, Leighton Contractors, Caterpillar and the Cat dealer in Western Australia, WesTrac, are providing a full solution for managing, operating and supporting Cat MineStar System and Command for hauling. The greenfield Solomon Mine has brought together the skilled team from Caterpillar, Fortescue, Leighton Contractors and WesTrac to deliver an efficient, cost effective autonomous mining solution.

Nov 1, 2013

By J. W. C. Wong, S. D. Miller, J. J. Jeffery

Pre-mining identification of acid forming mine and waste materials is of concern to the mining industry because of the potential for the generation of acid mine drainage, acid rock drainage, and soil acidity problems. Accurate identification of acid forming material is essential for developing appropriate waste management strategies to reduce environmental problems related to acid generation from sulphide containing wastes. The acid-base accounting procedure, in its various forms , is commonly used for pre-mining screening of mine and mine waste materials. The procedure is generally effective when used and applied correctly but is prone to incorrect interpretation of results which can have significant financial and environmental implications. This paper examines the acid-base accounting Procedure and the possibility of misuse of this method with special emphasis on the sampling method, the sulphide forms, the acid neutralization capacity, and the interpretation of results. Data from numerous coal, base metal, and gold mining operations are used to illustrate the application of the acid-base account. The data base indicates that overall, approximately 1/3 of all waste generated by mining and mineral processing is potentially acid forming indicating the need for correct identification and management. Problems associated with simple application of 'absolute' acid-base criteria for classifying acid forming material are highlighted and the need for developing site specific or 'relative' criteria is discussed and illustrated by case study.

Jan 1, 1991

By Y. C. Kim

Three rock fracture parameters define three points along empirical cumulative size (of rock fragments) distribution curves at Inspiration copper mine. These parameters are: rock quality designation (RQD), longest piece of intact rock and % of +1 inch. The RQD and the longest piece are actually measured on drill hole cores whereas % of +1 inch is visually estimated on the same cores. These size distribution curves are then utilized in a variety of engineering applications such as; slope instability analysis, blast design, copper recovery prediction from heap leaching, etc. The three rock fracture parameters for two dominant rock types (porphyry and schist) in the pit had to be estimated separately due to different rock fracture characteristics.' Both ordinary kriging (OK) with measured hard data only and soft kriging (SFTK) with hard and soft data were used to estimate each parameter. The cross validation of 100 measured sample values served as the-basis for evaluating the potential benefits of SFTK over OK. Use of subjective information during SFTK required obtaining (prior) probability distributions for all three rock fracture parameters. These distributions were obtained from the typical rock fracture parameters observed in drill hole cores falling inside the geologically interpreted structural domains with varying degrees. of fracture intensity and also through direct mapping along the exposed bench faces. Two different types of soft information were developed for this study; namely, Type "A" and Type "K". The former is based on sample distribution of fracture parameters whereas the latter is based on two step estimation designed to narrow the range of variation observed in data Type "A". The results of the cross validation were analyzed using a linear regression of actual values versus estimated values. The results confirm an improvement on the estimates made by SFTK with hard and. both types of soft data over those produced by OK with hard data only.

Jan 1, 1989

By J. H. McNamara

A process has been developed for the successful hydrometallurgical extraction of copper from sulfide ores. The extracted copper in the form of a salt is converted by reduction to copper metal. Purification of the metal is described which includes a description of the casting of ETP quality copper wire bars.

Jan 1, 1978