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By Norm Steenson

Rapid excavation includes rapid support and is the central theme of this paper. Over the last few years, enormous strides forward have been made in the excavation and material handling aspects of underground excavation. However, the technology necessary to support these rapidly created openings has lagged behind the other aspects. This paper would attempt to bring you up-to-date on the progress made in bringing ground support using shotcrete into the same productivity rates as the other cyclic operations. Shotcrete has become an acceptable material for temporary and permanent support for undergound openings. However, coarse aggregate shotcrete has been an expensive construction material. It has been confined in the main to difficult ground conditions where conventional methods of support have proved to be even slower and more expensive than shotcrete. There are two main factors influencing the productivity of shotcrete equipment. (1) Structural shotcrete as opposed to gunite requires 40% to 45% rock minus 3/4" in the mix design. The equipment to handle such aggregate content has been difficult to develop on a volume basis owing to the attritional nature of the material which causes intense wear problems on

Jan 1, 1974

By Shaning Yu, Yosry A. Attia

The purpose of this work was to investigate the feasibility of using column flotation as a floc separation technique. In this study, the ultrafine coal (minus 25 microns) slurries were cleaned by using the Integration of column flotation with selective flocculation. It was found that using column flotation as a floc separation technique during the "cleaning" stage, achieved much better results than that either using column flotation as a rougher separation technique for coal flocs, or using It directly to recover the ultrafine coal from the slurries without adding selective flocculant. Thus, the ultrafine coal slurries were first separated by selective flocculation process to reject a certain amount of the dispersed ultrafine ash minerals, and to aggregate the ultrafine coal particles as flocs. Thus, the entrainment of ultrafine ash minerals Into the coal floc-froth concentrate during flotation could be considerably reduced. Subsequently, the coal flocs were further "cleaned" by column flotation. The experimental results Indicated that this approach was technically feasible and particularly suitable for a slurry containing a large amount of ultrafine particles. The effect of flotation time, and collector dosage on column flotation of coal flocs were also Investigated and reported In this article.

Jan 1, 1988

By P. R. G. Brandão

In this investigation, the differences in the absorption spectra of etheramines, fatty amines and condensates, mostly present as acetates, from several suppliers are characterized by means of infrared spectrometry. Sharp differences were observed in the absorption spectra of three types of amines and derivatives. Etheramines show a characteristic and well-defined peak at 1,114 cm-1. This peak is due to the ether C-O group and differentiates etheramines from the other classes. The absence of such a peak indicates that the species is not an etheramine. The distinction between condensates and fatty amines is made by the presence of a sharp peak around 3,200 cm-1. This peak is probably due to the proximity of the N-H amine groups and C=O carbonyl groups in the amide portion of the condensate's molecule and by different and better-defined bands in the 1,800- to 1,500-cm-1 range. The flotation performance of these amines was evaluated by means of the laboratory-scale flotation of an itabirite ore. The etheramines proved to be the most effective collectors for this system. Monoamines presented better performance than diamines for the ore under investigation.

Jan 1, 2002

By A. L. DeVegt, H. G. Bayer, C. J. Buisman

During the last ten years, Paques Inc. has been engaged in the development and installation of treatment systems to remove sulfur compounds from water and gaseous streams using biotechnological processes. Metal and sulfate can be removed from mine waters in two biological steps. In the first step, sulfate-reducing bacteria converts sulfate to hydrogen sulfide (H2S). The HS reacts with the dissolved metals to form insoluble metal sulfide precipitates. In the second step, sulfide-oxidizing bacteria convert excess H2S to elemental sulfur. The Budelco Zinc Refinery in The Netherlands installed a groundwater treatment system to remove metals and sulfate using the biological steps described above. The system has been operating since May 1992 and has been treating 5,000 m3/d (180 thousand cu ft/day). A pilot plant began operation in November 1995 at Kennecott's Bingham Canyon Utah copper mine to develop processes for metal and sulfate removal from groundwater and for the selective copper recovery from leach water. The principle of the biotechnological methods, the full-scale experience and an overview of the test program at the mine are presented

Jan 1, 1999

By S. P. Banerjee

There has been a phenomenal increase in production of coal from opencast mines in India. At the same time environmental problems caused by mining are receiving greater atttention. Deterioration in ambient air quality due to increased concentration of suspended particulate matter (SPM) in and around an opencast project is a major problem. Some measured values of SPM level around opencast mines in diff coalfields show that in many cases the TLV of 500 ug/m^3 is exceeded. The impact of dust emission from a mining project on surrounding areas are estimated by using computer models for air pollution dispersal but such treatment suffers from errors in predicting the dust load and failure to take into account the terraced nature of the opencast mine site. The haul roads have been identified as the most prolific source of dust and some recent trials on haul road dust consolidation in Indian mines are mentioned in the paper. Statistics regarding pneumoconiosis cases in Indian coal mines for the last decade are presented to show an increase in reported cases and a gist of the recently amended regulations on the subject of precaution against dust is mentioned.

Jan 1, 1991

By J. E. Murphy, R. Y. Wan, K. R. Sandgren, M. C. Fuerstenau

As part of a U.S. Bureau of Mines program to evaluate alternatives to sodium cyanide in gold leaching, three organic nitrile compounds were tested for their effectiveness as gold lixiviante. The organic compounds examined were malononitrile, acetonitrile, and cyanoacetamide. The reagents were tested on an oxide ore, two carbonaceous ores, and a eulfidic ore. Acetonitrile and cyanoacetamide were shown to be ineffective gold leachante. Malononitrile was the most successful of the organic lixiviants. On an oxide ore, malononitrile performed shilarlyto sodium cyanide with extractions of around 80 pct. For carbonaceous "preg-robbing" oree, sodium cyanide was completely ineffective while malononitrile extracted 24 pct of the gold. When using a resin-in-leach technique, extraction with sodium cyanide increased to 60 pct and the extraction with malononitrile increased to 80 pct. On the sulfide ore, sodium cyanide and malononitrile performed similarly with 80+ pct extraction as long as the pH of the malononitrile solution wae maintained above 10.5. Malononitrile is six times less toxic than sodium cyanide as measured by LD, levels. Therefore, malononitrile has a significant advantage over eodium cyanide, but its high cost and undemonstrated usefulnees make it unlikely to gain acceptance.

Jan 1, 1993

By F. L. Wilke

In the german hard-coal mining industry the mechanization of longwall faces and the machinery used for the extraction process have reached such an extent, that an extensive increase in productivity and face performance is not likely to be expected. At present, the greatest amount of man-shifts is needed for operations such as tunneling, transportation and haulage (fig. 1.). The most restrictive parameter, especially considering the possible ad- [ ] vance rate of faces, is the comparatively low advance rate achieved in drifting operations. Therefore improvements in productivity and advance rates of drifting operations will have considerable influence onto the extraction rate of the faces. The importance of drifting operations - and especially the so-called "conventional drifting by drilling and blasting" within the scope of long- term planning strategy of the german hard-coal mining industry is reflected by the development factor. This factor is given by the ratio: cubic meters of rock excavated in drifting per 1.000 tons saleable coal produced. In 1973, which is considered to be the beginning of the oil-crisis, this factor was determined to be 17.7 m3/ 1.000 tons sale- able coal.

Jan 1, 1982

By Patricio A. Espinoza, Aldo Casali, Cristian Ardiles, Guillermo González

Cluster analysis is used to design grade soft-sensors in a rougher flotation plant and a ball mill overload soft-sensor. Soft-sensors are virtual sensors which either replace unavailable actual sensors or infer measurements for non existing sensors. In the case of the grade soft-sensors clustering serves to determine clusters of related operating points. To each cluster there corresponds an ARMAX model structure whose parameters are estimated using only the points in the corresponding cluster. Thus a much better correlation is found than if all the data points were used for a global model. The problem of identifying clusters when the measurement of the real sensor is not available is addressed. In the case of the overload soft-sensor, variables were selected which are related to overload, either from a phenomenological point of view or according to operator experience. Different clusters are formed, some of which are identified as determining an overload condition or a possibility of such condition. Each of these clusters has a set of operating conditions which suggests the corrective action to be taken when necessary. Both kinds of soft-sensors are tested with industrial plant data and promising preliminary results are obtained.

Jan 1, 1995

By Roderick K. Davey

The objective is to develop a short-range mining plan which satisfies management and operating criteria and also "dovetails" with the long-range mining plan. In the past years, this objective was accomplished entirely by manual methods. Today, the computer is used to assist the engineer with this task. The results provided by these programs usually are incomplete and require further manual manipulation. The advantage of using the computer programs is that the program can be used to evaluate alternative plans on a first-cut basis minimizing the manual work. Subsequently, the most promising alternatives can be analyzed in more detail, commencing with the first-cut results. In this specific case history, one technique for using computer programs to assist with short-range mine planning will be discussed. Some of the basic operating and management criteria considered directly and indirectly are as follows: (1) operating criteria which include minimum and maximum shovel cut size, equipment performance, haulage roads, requirements for blending, and plant capacities; and (2) management criteria which consist of production requirements, cash flow requirements, return on investment, market demands, and availability of capital.

Jan 1, 1979

By C. L. Karr

Researchers at the U. S. Bureau of Mines have developed a technique for producing adaptive control systems using fuzzy logic and genetic algorithms. These controllers can be used to efficiently manipulate complex systems in real-time. Furthermore, they can achieve an acceptable level of control despite limited feedback in the problem environment. The control systems that result from the implementation of the Bureau-developed technique are able to recognize when changes have occurred in the problem environment, evaluate the magnitude of these changes, and alter the strategy being used to control the problem environment. Fuzzy logic is used to provide the controller with a rule-base that mimics the "rule-of-thumb" approach generally adopted by humans in the area of process control. Genetic algorithms are used to provide the controller with the adaptive capabilities necessary for the control of complex time-varying processes popular in the minerals processing industry. The effectiveness of this technique is demonstrated on a laboratory pH titration system. The pH system includes a changing setpoint, titrants with varying concentrations, and the possible addition of a buffering solution.

Jan 1, 1993

By Solomon S. Katz

As more and more computer software is written for geological mapping applications, the users of the software are discovering the problems of transferring data between the programs, maintaining correct data and integrating maps produced last week with those produced today. One way to deal with these situations is by using a geographic information system (GIs). Last September the USGS and National Academy of Science held a 5-day GIs symposium on integrating technology and geoscience applications (USGS, 1988). It was followed in October by GEOTECH '88 (Peters and Krajewski 1989) which had a session exclusively for GIs applications in the Geo-Sciences. Editorials in Geobyte (Leonard, 1986, 1988) suggested that geographic information systems will be the next major computer programs to be adopted by the mineral industries. As far- back is 1985, the Computer Oriented Geological Society (COGS) printed An Introduction to GIs in their newsletter (Katz, 1985). About 20 years ago, a revolutionary idea occurred in the world of business data processing. It was the idea that all related data be stored in a standard format, in a single place and that all related computer application programs would use the same data.

Jan 1, 1989

By Munson R. McKinney, Bryan A. Slim

To date some 1,000 exploration targets (by way of adits, mine dumps, shafts, outcrops and unstoped mine areas) have so far been identified using an interactive data base system to query a digital data base comprising topographic, cadastral geological and mine components developed as a compilation of old plans, records, surveys and recently flown aerial photography. The exploration targets are intended for early follow-up as part of a 1987 exploration programme to investigate the reserve potential of the former producing property located in southern Utah. Of further interest is the unscrambling of old mine plans to provide drill targets for investigation of unstoped reserves with one target being a possible 800,000 tons in part of the lower workings. The project site encompasses about 3,200 acres of mainly patented lode claims covering most of the claims and mines of the Gold Mountain mining district formed in 1889. Turn of the century mining saw several mines operating whose total production was at least 143,000 oz. gold and 460,000 oz. silver from steeply dipping veins up to 20 ft. or more in thickness.

Jan 1, 1987

By A. Pavlides

The purpose of this work is to conduct a preliminary analysis of the spatial variations of the thickness of lignite layers in the area of the Amyndeo mine, and to estimate the lignite reserves of the mine. The reserves are estimated by the method of the Voronoi diagrams, using a group of mirror points to close the polygons around the boundaries of the mine. Two data sets are investigated. The first one corresponds to an exhausted part of the mine. The derived reserves estimates are compared with the actual data obtained by the Public Power Corporation (PPC) to validate the analysis. The second data set extends over the entire mine, and it is used to derive an approximate estimate of the total lignite reserves. A geostatistical analysis of the total layer thickness is performed. The experimental semivariograms are evaluated for both data sets in different spatial directions. Two possible theoretical models for the experimental semivariogram (the exponential and a novel Spartan model) are compared and discussed. An interpolated kriging map of the total thickness variation is produced accompanied by a map of the kriging precision. The performance of kriging interpolation is discussed in terms of cross validation measures.

Jan 1, 2007

One of the major objectives of cost analysis is to enable the manager to predict the financial outcomes of decisions. To accomplish this, the future costs and benefits of alternative courses of action must be determined. If care- fully used, information about past financial performance can be helpful in this analysis despite the fact that, by definition, financial reporting information is historical. In many cases, both revenues and costs need to be estimated for decision- making. For the production manager, additional revenue is a result of increased throughput or recovery of valuable material from the stream of mined material. A reduction in operating cost, although similar to a revenue increase in its financial impact, is estimated using slightly different techniques. Generally, the estimation of cost is more difficult than the estimation of revenue. Most cost estimates have two components: an estimate of fixed costs and an estimate of variable costs. As discussed in chapter 5, the total cost of an activity during a specified period can be expressed as: Total cost = (Variable cost per unit of activity) x (Units of activity) + Fixed cost or TC = VX+F

Jan 1, 1999

By J. R. Stoltz, E. Thompson, S. Pattee

On May 15 and 16, 1999, a mine ventilation survey was performed in the 705-m- (2,312-ft-) deep Cayuga Mine, Cargill Salt Division, Lansing, NY. The purpose of the survey was to develop a numerical model of the existing ventilation system and to perform a computer simulation study for long-term environmental and ventilation planning. Because the natural ventilation pressure (NVP) has significant effects on the ventilation system at the Cayuga Mine, there was a need to assess the NVP acting in the mine. Due to the ventilation arrangements in the Cayuga Mine, the authors decided to use the direct-measuring method to determine the NVP by measuring differential pressure across the automatic fan door. This difference in pressure was measured immediately after the fan was stopped and the automatic door was closed to stop the flow throughout the entire mine. To show seasonal changes in NVP, two additional measurement for NVP were performed, one on Aug. 22, 1999, during the hot (summer) season, and another on Feb. 6, 2000, during the cold (winter) season. The mutual interaction between the natural ventilation pressure and the main fan at the Cayuga Mine is also discussed

Jan 1, 2003

By M. J. Virnig, C. P. J. Van Vuuren, A. J. Botha

The Zadra, AARL and organic elution processes and variations of them are presently widely used to recover gold from activated carbon. Despite this the study of the kinetics of elution have received relatively little attention. It is the aim of this study to investigate the rate processes taking place during elution in both inorganic and organic solutions. Batch adsorption and elution rate and equilibrium experiments were performed. The spatial concentration of gold inside carbon particles at various stages of the adsorption and elution processes were measured with a scanning electron microscope using an image analyzer to control and manage the micro-analysis data. The activated carbon particles exhibited film and intra-particle mass transfer rate- controlled behaviour during adsorption in a caustic aqueous solution at 95°C. Elutions in the aqueous caustic acetone solution at 30°C and the caustic aqueous solution at 95°C were unaffected by change in stirring rate. Elution was modelled by desorption reaction rate-control at the outer surface of the carbon particle. Adsorption and elution isotherms under duplicated solution conditions showed reasonable agreement for the inorganic solution and a large disparity for the organic solution.

Jan 1, 1993

By A. J. Hendron, B. Mohraz, R. B. Peck

INTRODUCTION The state of the art of soft-ground tunneling was discussed in detail by the senior author at the 7th International Conference on Soil Mechanics and Foundation Engineering held in Mexico City in 1969. Little can be gained by repeating the information assembled at that time. Hence, in this report, only the briefest summary will be given of the overall state of the art and attention will be concentrated on trends and developments since 1969. A characteristic of recent developments is the continued trend toward use of shields and excavating machines. The implications of this trend with respect to design and construction, and particularly with respect to the treatment of unfavorable ground conditions, will be examined. Settlement associated with lost ground, a subject as old as tunneling itself, will be reviewed and methods will be considered for its reduction. Design of tunnel supports was discussed in detail in 1969 with respect to essentially rigid or essentially flexible types of linings. In this report, a definition of flexibility will be considered and design procedures suggested for linings of flexibility intermediate between the two extremes.

Jan 1, 1997

By Salt Lake City Research Center, D. G. Foot, J. D. McKay

As part of its research program on column flotation, the Bureau of Mines, Salt Lake City Research Center has performed studies on (1) column flotation amenability and comparison with conventional flotation results for over 15 mineral systems, (2) alternative methods for improving column bubble generation systems, (3) mineral behavior within a column, and (4) the effect of changes in column operating parameters on flotation grade and recovery. Based on results from these studies, flotation columns (1) are capable of producing higher grade concentrates in fewer stages than conventional flotation cells at equivalent or increased recoveries, (2) require less retention time than conventional flotation cells, and (3) can be divided into cleaning and collection zones that have characteristic mineral-upgrading-per-foot values. Attempts to improve the column air sparger have led to the development of a superior external bubble generation system, which can (1) achieve increased air holdups. (2) produce bubbles from 400 Um to 4,000 Um average bubble diameter with minimal frother addition, (3) provide superior bubble size control, and (4) be maintained without column shutdown. Efforts are continuing to improve column flotation and transfer successful technology to industry.

Jan 1, 1988

By T. T. Chen, J. L. Jambor, J. E. Dutrizac

A reconnaissance study of the neutralization potential of 30 diverse minerals, 28 of which are silicates and aluminosilicates, has shown that most of these minerals contribute minimally to the neutralization potential (NP) in standard static tests. Feldspars in particular give low NP values and would not be expected to attenuate the acidity to any significant extent in acid rock drainage settings. The BET-determined surface areas of the minerals vary considerably, and the large surface areas of some of the pulverized samples have clearly affected the NP values even though the standard static-test protocol was used for the preparation of the samples. The low NP values of most silicates and aluminosilicates are in general agreement with the laboratory-determined slow dissolution rates for these minerals. The results suggest that, in the prediction of whether rocks will be acid-producing, the most realistic measure is that of the carbonate content. In mine wastes from metalliferous ore deposits, the contribution to the NP by the non-carbonate gangue assemblage is unlikely to be more than a token amount until well after the establishment of an acid rock drainage situation.

Jan 1, 2000

By William D. Hanson

Celestine (celestite) (SrSO4), the primary ore mineral of strontium, is present in the DeQueen Limestone Member of the Trinity Group (Lower Cretaceous) in Sevier, Howard, and Pike Counties, southwest Arkansas. Two mappable celestine beds have been identified. One bed is commonly 3-5 in. thick, but ranges up to 18 in. in thickness; the other bed is generally 2-3 in. thick. The beds are concordant within the DeQueen Limestone and were formed by precipitation from periodically restricted sea water. Reports concerning celestine date back to 1929, when Hugh D. Miser and A. H. Purdue mapped the geology of the DeQueen and Caddo Gap quadrangles. A small amount of celestine was produced in the early 1940s in Howard County. During 1941, the J. W. Hintze Company collected 1,500 pounds of celestine for testing purposes. In 1942 and 1943,750 test holes were drilled by the Bennett-Clark Company in Howard County. Afterward, approximately 90 tons of celestine was open-pit mined and shipped to Texas for processing. Since then, no mining of celestine in Arkansas has taken place.

Jan 1, 1999