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By P. Massacci, F. La Marca, G. Bonifazi

Some deposits of inhomogeneous materials, which occur near the surface and are exploitable by open-pit mining, may he characterized in real time prior to mining through groundsurface imagery. If the slice to be stripped is not overly thick, surface texture and color properties may be extrapolated to its entire thickness. Image-analysis techniques for processing ground-surface images acquired in situ or in the laboratory shortly after their acquisition have been developed. These images yield pattern vectors representative of red, green and blue (RGB) color component distributions and hue, saturation and brightness (HSB) texture parameters. The techniques were applied to a sandy ore deposit containing three lithotypes. Geostatistical analysis indicated that the data used to characterize the lithotypes were reliable. The correct recognition of the lithotypes was carried out using a multibarycenter classification algorithm. Such in situ image-analysis procedures provide a means for selecting the ore to be mined, selecting the proper ore-processing method and determining the appropriate blend to he processed. This can be done either before or during mining.

Jan 1, 2000

By Andrew T. MacKenzie, Paul A. Rantala

Predictive pastefill rheology (flow characteristic), models have long challenged pastefill practitioners. While the methodology and practicality of recipe formulation is attainable in most locals, the remaining challenge has been to devise a predictive mathematical or empirical model of paste flow characteristics. Flow phenomenon can now be assigned mathematical and physical basis. The authors herein disclose physical and mathematical methods that demonstrate how operators could proceed when designing reliable pastefill systems. Knowledge presented will allow users flexibility in adjusting flow-rates. Laboratory data shows stiff pastefill delivery design can be derived through mathematical relationships of particle size, material characteristics and pipe diameter.

Jan 1, 2001

By J. D. Miller

Fluid flow phenomena and therefore the flotation efficiency of air-sparged hydrocyclone (ASH) flotation are strongly dependent on operating and design variables such as air and slurry flow rates, underflow and overflow opening areas, percent solids of the feed, reagent levels, particle size and ASH length. Time-averaged multiphase flow characteristics, as determined by X-ray CT (described in a previous publication), are used to understand and explain the steady-state ASH flotation of quartz. A detailed parametric study of quartz flotation by a nominal 2in. diam. air-sparged hydrocyclone (ASH-2C) revealed the influence of these variables on the flotation response, which is discussed in terms of the multiphase flow characteristics. Thus, a phenomenological description of quartz flotation has been established to assist in the further development and utilization of the ASH technology.

Jan 1, 1996

By S. Kesler

Rössing Uranium Limited has operated since 1976 a large open pit uranium mine and extraction plant at a remote site in the Namib desert, South West Africa/Namibia. The geology (Berning, I., et al. Economy Geology) and the technical aspects concerning mining, grade control and metallurgy have previously been described (Rössing Uranium, Mining Magazin and Whyllie, R.J.M. "Rössing Uranium reaches rated production", World Mining). The improvement of leach 'extraction has been reported in 1984 (Kesler, S.B. et. al. "Uranium extraction at Rössing") and the installation of a central process control system has been described (Kesler, S.B. et al. "The introduction of a central process system at Rössing"). At the beginning of 1983 a decision was made to develop a computer system for metallurgical plant optimisation which included mass and volumetric balances, analytical assays for up to 5 chemical elements and the costs for the major consumables. Within 10 months this computer system was developed and implemented. A large number of test runs were made and computer studies were undertaken. The metallurgical division now has a scientific tool for production; planning for actual comparison with plant results and for strategic investigations and decision making.

Jan 1, 1986

By Timothy M. Dyhr, Marie Garrett

The Cannon Mine gold project has been perceived as unique for being developed in an area characterized by orchards and suburban residences. The Cannon Mine was permitted and developed successfully in this setting. However, the ability of companies to permit, develop and operate mines in mated areas is becoming more difficult as a result of opposition by residents and increasingly stringent regulation. The challenge to the mining operator in the future on otherwise economically attractive mineral deposits will be the ability to explore and develop these types of projects successfully and cost- effectively

Jan 1, 1987

By Kumar Vikram

Rich reserve of prime quality limestone in east khasi hills of India and abundant quantity of low-cost fuel (Natural Gas) in Bangladesh made Lafarge Surma cement limited a joint venture company of Lafarge France and Cementos Molins Spain to envisage an integrated cement plant at Chatak District-Sylhet) a bordering town of Bangladesh. Since April 2006 the single flight 17 km Long Belt Conveyor (LBC) built by M/S Larsen & Toubro Ltd. (L&T), ECC Division an engineering and construction company of India, is feeding limestone/shale to the Lafarge Surma cement plant. This engineering marvel was created on a turnkey basis with technology support of M/S Aumund France

Jan 1, 2008

By L. W. Saperstein, R. J. Sweigard, D. L. Simpson

Deep tillage is widely used as a means of alleviating excessive soil compaction. There has been some concern that the voids created by deep tillage may collapse before a more natural soil structure develops, resulting in recompaction subsequent to deep tillage A laboratory investigation was conducted to determine the feasibility of pneumatically injecting organic material into the voids produced during deep tillage in order to prevent any significant recompaction from occurring. Various amendments were injected into the soil during laboratory tests using a small-scale ripping and injection system. Measurements were made of selected soil proper Pies to evaluate the feasibility of this method.

Jan 1, 1994

By J. Bouchard, V. Aubé, A. Desbiens, R. del Villar

The metallurgical performance of column flotation is determined by the concentrate grade and recovery. Although the former can be continuously measured using an on-stream analyzer, the latter must be estimated by a material balance calculation based on seldom verified steady-state assumptions. Consequently, the automatic control and optimization of flotation columns should be performed using secondary variables having a strong influence on the metallurgical performance, such as froth depth, gas hold-up or bubble surface area flux and bias. The aim of this paper is to present a method to get froth depth and bias measurements using virtual sensors. Fractional factorial experiment design for the neural network calibration of the bias sensor, pilot plant results, and eventual industrial applications – including the possibility of achieving effective real-time optimization from bias and froth depth measurements – will also be discussed.

Jan 1, 2003

By J. T. Sitarski, R. C. Emmett, L. W. Luinstra, R. P. Klepper

A mining operation in Zimbabwe produces a pyritic gold concentrate that requires oxidative pretreatment prior to cyanidation in order to liberate 80 percent of the gold values. Bio- oxidation offered the potential of increased gold recovery and was considered to be an economically advantageous alternative to the existing practice of roasting the concentrate. Based on bench- scale test work, a small bio-oxidation plant, capable of processing approximately 50 percent of the concentrator production, was installed at the mine to evaluate this approach. The plant included two 57 m3 bioreactors in series and the ancillary equipment needed to prepare the feed concentrate, to wash the leached residue prior to cyanidation, and to neutralize the waste liquor. The plant was operated for a year-and-a-half, and the conditions needed to achieve a 90 percent liberation of gold values were determined. A number of critical technical problems were encountered, and many were resolved on-site. Others have been addressed since the pilot plant was moth-balled in June 1988. Valuable insight was gained from the operation of the pilot plant, which has provided useful guidance for continued process and equipment improvement.

Jan 1, 1990

By T. Foster

The continuous operation of decanters in the mining industry relies heavily on the use of synthetic flocculants. Today, as plants seek to lower production costs by increasing throughput it is necessary to obtain optimum performance from the flocculant. Factors affecting such optimization include charge and molecular weight selection, and efficiency of mixing the highly viscous polymer solution with the feed slurry. Beyond maximizing dilution of the solution, the last factor is often ignored. This paper describes a series of calculations, based on fundamental transport theories, that have been used to describe flow conditions within decanter feed wells and to help select flocculant addition points. Examples are shown for the case of hydroxamated polyacrylamide flocculants in the Bayer Process, where proper selection of the addition points can result in lower flocculant dosage and better control of the decanters.

Jan 1, 1996

By Hans von Michaelis

Gold metallurgy has advanced remarkably over the last decade. Even more significant progress will be made over the next five years, particularly in the application of advanced comminution techniques and control, preconcentration (flotation, ore sorting and coal gold agglomeration), enhancement of cyanide leaching technology, non- cyanide leaching, treatment of refractory ores and concentrates, and improved recovery systems. Carbon adsorption processes have become standard practice for ores with relatively high gold/silver ratios, but ion exchange potentially offers distinct advantages and has recently been demonstrated to perform better in at least one application. Even in the established zinc precipitation and CIP processes several important practical improvements are emerging as experience is gained at the ever increasing number of operating plants. Improved process control and reduction of reagent consumption costs are two important goals of industry at this time.

Jan 1, 1989

By W. Stahl, K. Keller

In addition to classifying bulk material, vibration screens are commonly used in dewatering. However, the lack of a comprehensive physical theory of dewatering often leads to difficulties in the design and operation of the vibration screens. First, in this report, the dewatering of bulk material are shown based on a physical model. Because of tile oscillatory motion of the liquid in the bulk, the inertial force of the accelerated liquid and the dripping of water out of the bulk or screen must be taken into special consideration. The physical model put forward shows the effect of the various operations parameters of dewatering screens. A comparison between dewatering theory and practice are shown by measurements using coal, limestone, etc. Dewatering measurements conducted on a vibration screen demonstrated that different vibration frequencies and rates of acceleration lead to different residual moistures. Finally, the possibility of improving vibration dewatering is described.

Jan 1, 1998

By W. A. Steingraber

This paper discusses the application of deep well disposal techniques to the problem of disposing of large volumes of low level radioactive wastewaters generated by the in situ uranium mining industry in Seth Texas. Data is presented on wastewater composition and volumes, geologic and hydrologic parameters of the disposal reservoirs, tell construction techniques, well operation, well monitoring requirements, and critical factors in evaluating the Safety and environmental impact of a deep injection well system.

Jan 1, 1980

By Jessica M. Wempen, Dallan J. Coons, Bailey S. Simmons, Michael K. McCarter

Gate-road yield pillars are subject to increases in stress as the longwall face advances toward the pillars. Increases in pillar stress can be inferred by measuring roof/floor convergence surrounding the pillar. This paper presents a case study of convergence measurements surrounding a two-entry gate-road yield pillar in the head gate of a coal mine. Convergence was measured over a six-month period, as the longwall face approached and passed the pillar. Measurements were collected at eight locations surrounding the pillar: four locations in the travelway and four locations in the beltway. In addition to convergence stations, the pillar was instrumented with an array of seismometers. In future analysis, convergence measurements will be compared to seismic interpretations. This study reports on the geology and geometry of the longwall panel, the roof and rib support, the change in convergence over time, and the physical properties of coal and parting. Additionally, the convergence measurements are compared to pillar safety factor distributions derived from a finite element model. The convergence measurements contribute to the knowledge of when yield pillar abutment loading, caused by the encroaching longwall, is first detected. Knowing when abutment loading begins to yield the pillars can help define when standing secondary roof supports are required for head gate entry support.

By J. E. Gray

Before specifications are discussed it may be well to define the term "Mineral Aggregates." Professor K. B. Woods (1) defined "Mineral Aggregate--An aggregation of sand, gravel, crushed stone, slag, or other material of mineral composition used in combination with a binding medium to form bituminous and portland cement concrete, macadam, mastic, mortar, plaster, etc., or alone as in railroad ballast, filter beds, and various manufacturing processes, such as fluxing, etc. " This definition is too all inclusive for the purposes of this paper; therefore, this discussion will be confined to specifications for natural aggregates which means sand and gravel and crushed stone, and limited primarily to coarse aggregate which is aggregate larger than one-quarter inch in size. To the uninitiated, this may seem to be a very limited subject on an unimportant material. However, aggregates are essential in all types of construction. The tonnage and value of these two aggregates produced in the United States during 1959 as reported by the Bureau of Mines were as follows: Sand and Gravel 729,895,000 tons valued at $728,527,000 Crushed stone 581,721,000 tons valued at $824,411,000

Jan 1, 1961

By C. P. Shen, H. C. Tsai, Bennie Chu, Y. S. Hsieh

The Pinglin tunnels are situated within the fold-and-thrust belt structural region in Taiwan, due to continent-arc collision and plate tectonic setting. The pilot tunnel TBM (§=4.8m) became stuck ten times with the standstills to date. The westbound main tunnel TBM (§=11.74m) was buried in a collapsing calamity. The main tunnel TBM shall identify and overcome the adverse geology with high volume of ground water ingress itself. This paper presents our experience and methodology through the adverse geology with Pinglin large TBM.

Jan 1, 1999

By G. A. Rowell, T. M. Barczak, J. C. Zelanko

The US Bureau of Mines conducted a multifaceted geomechanics research project at a bump-prone longwall coal mine in eastern Kentucky. This mine presented a unique opportunity to study coal mine bumps because the problem appeared to be confined to areas beneath a sandstone channel of limited areal extent. The Bureau's research plan sought to exploit the uniqueness of the site by monitoring strata behavior and longwall support reactions as the longwall face approached and passed beneath a sandstone channel. The study incorporated static pillar stress and strata deformation measurements, shield support leg pressure measurements and microseismic monitoring, as well as geologic mapping and the collection of observational data. Data collection was underway when a major coal bump occurred on the longwall face at the mine. Pillar behavior (load and deformation), shield loading and microseismic activity were monitored prior to, during and after the bump. Observations in the tailgate indicated that these pillars were failing prior to and following the face bump. Shield load data, evaluated in an effort to identify trends that could be used to forecast coal bumps, appear to provide a measure of the effectiveness of destressing operations conducted on the face (e.g. shot firing). Analyses of microseismic data revealed anomalous values associated with microseismic "energy" prior to the face bump. In addition, microseismic source-location data and underground observations provided some insight as to the sequence of pillar and face bumps.

Jan 1, 1992

By Bryce T. Tripp

Utah's abundant industrial rock-and-mineral resources support a relatively small but important sector of the State's economy. In 1983, six of the top 10 nonfuel mineral commodities (by value) were industrial commodities. Portland cement was ranked fourth, potash fifth, halite sixth, phosphate seventh, construction sand and gravel eighth, and lime tenth. Portland cement was produced by three operators, principally from the Jurassic Twin Creek Limestone. Potash was produced by three companies from Pennsylvanian beds in the Paradox Basin, surface brine of the Great Salt Lake, and subsurface brines of the Great Salt Lake Desert. Halite was produced by eight operators, primarily from surface brine of the Great Salt Lake. Additional production came from salt beds in the Jurassic Arapien Shale, solution mining of the Pennsylvanian Paradox Formation of the Hermosa Group, and subsurface brines of the Paradox Basin. Phosphate was mined by one company from the Permian Meade Peak Phosphatic Shale Member of the Park City Formation. Construction sand and gravel were produced by dozens of operators, primarily from Quaternary Lake Bonneville beach and nearshore deposits. Lime was produced by four operators from Paleozoic formations in the Basin and Range physiographic province of Utah. The future production of these and other industrial commodities, though individually uncertain, is expected to increase gradually as a group. Factors favorable for the future of the industrial commodities industry in Utah include large to almost unlimited resources for the major commodities, a healthy projected population growth, an abundant local supply of relatively inexpensive energy from coal and natural gas, and a favorable corporate tax structure and business climate.

Jan 1, 1987

By A. M. Marabini, G. Belardi, E. Spaziani

The objective of this research was to investigate the possible application of integrated circuits to the concentration of talc from the Valmalenco mine, located in northern Italy. The investigation was aimed at producing a high-grade product (low in impurities such as iron and carbonate) that would be suitable for industrial applications. Because of the presence of accessory minerals, the talc concentrate from this ore is not, at the present time, suitable for industrial applications.

Jan 1, 1996

By Jacques Deraisme

Geostatistics has been applied in many mining feasibility studies throughout the world during the last decade. Recently geostatistics has begun to be applied to the field of mining processes by attempting to aid in the definition of the best mining policy. For a feasibility study the grade-tonnage relationships give a reasonable order of magnitude estimate of the ore reserves within the deposit. But the reserves that will actually be recovered, will vary depending upon the mining methods and the technical means used. The profit earning capacity of the mining project is determined by a great many factors, such as for instance: accessibility of reserves to extracting machines, the haulage distance between the mine and the mill, the variability of produced ore (tonnage and grades) which could necessitate stockpiles or blending areas?

Jan 1, 1979