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By A. G. Journel

The indicator random function formalism allows a common coding of hard numerical data, constraint intervals, and soft qualitative information as prior probability distributions. The soft kriging algorithm allows interpolating these priors into posterior probability distributions of the unknown. The curse of ?negative kriged grades? is solved. The consideration of additional soft information, whenever deemed necessary, becomes possible within the framework of well-proven kriging techniques.

Jan 1, 1986

By Leonidio Stegmiller

Since the petroleum crisis in 1973, charcoal1 is being considered one of the most important fuel for the Brazilian consumers, mainly for pellet's producers. In replacing fuel by charcoal mixed up with ore, obviously one of the first thing to be investigated is its influence in the product's quality. Special attention has been given to the metallurgical characteristics. This paper infocus the effect of increasing dosings of charcoal to the pellet's porosity and how other physical and metallurgical characteristics will be affected accordingly. This work was carried out using two different finesses of charcoal and dosing varied from 0.5 to 2.0%.

Jan 1, 1982

By Theodore H. Budd, Austin M. Cooney

The North Shore 9 Collector System comprised an integral part of the Milwaukee Metropolitan Sewer District's Water Pollution Abatement Program. The project required the construction of 1,490 m of tunnel, ranging from 1.5 m to 4.6 m in diameter along three separate alignments beneath arterial streets traversing Milwaukee's central business and cultural districts. This paper details the various aspects of the tunnel drives which were accomplished using two Lovat EPB type TBMs in conjunction with pipe-jacking procedures. Shaft configurations developed for the project, including ancillary subsidence mitigation components and portal pressurization facilities are discussed. Anomalies in observed soil behavior at variance with the parameters delineated in the project's geotechnical report are addressed.

Jan 1, 1993

By Ronney Rodrigues Silva, Renata Mendonca, Gabi Knesel, Cathrine Monyake

Locus Mining is working side-by-side with a prestigious iron ore company to evaluate the addition of Locus ESG-friendly green flotation reagents with the primary goal of improving recovery and grade. In this paper, we will focus on the cationic reverse flotation application. The most “established industry” reagents for cationic reverse flotation are amine as the collector, starch as the depressant, and in some cases frothers are also used (among them MIBC, pine oil, others). Here, we evaluate the synergies of different classes of eco-friendly biosurfactants and industry-standard reagents during the cationic reverse flotation method. Exploratory research was done first with an analog sample under different pHs, eight different biosurfactants with starch and no-starch, and a customized DOE was used to perform 145 microflotation tests. The results show Separation Efficiency from 20% (baseline) to 50% (biosurfactant), and Selectivity from 3.27 (baseline) to 5.67 (biosurfactant). Optimized result conditions were then applied to the iron ore samples received from our client to perform flotation tests on a Denver Lab cell. Similar results were obtained by improving Separation Efficiency and Selectivity, which corroborate with the previous work.

Feb 1, 2025

By L. Evrard, M. Van Camp, J. Y. Yen, R. G. Reddy, D. Mantha

Viscosities of two industrial lead blast furnace slags have been experimentally determined as functions of composition and temperature. A Brookfield viscometer with alumina rods and crucibles were used. Experiments were carried out between 1200 and 1573 K in an argon atmosphere with up to 5% addition of FeO, MgO, and SiO2 to the slags. Results showed that 1) the viscosities of two slags decreased with increase in temperature; 2) addition of FeO decreased the slag viscosities; and 3) addition of MgO and SiO2 increased the slag viscosities. Use of the above slag compositions with the addition of FeO is recommended for successful lead smelter operation.

Jan 1, 2005

By P. G. Corser

A gold and silver open-pit mine located in northwestern Chile contracted ACZ in 1991-92 to assess the stability of their spent ore pile and to determine the cause and magnitude of cyanide contamination associated with leaching operations. The mine is a conventional open-pit located at an elevation of approximately 4,800 meters (m.) (15,744 feet). A spent ore pile is located approximately 2,000 m. southwest of the mine and approximately 1,000 m. northeast of the active pad and plant facilities. The pile was constructed on a gentle northwest slope dipping 12 to 13 degrees. The pile is bordered by a small river to the northwest and by a larger river to the northeast. Both rivers eventually flow into Bolivia. Heap leaching and processing commenced at the mine in 1988. Since 1988, nearly 6.0 million tons of ore at an average grade of 1.96 grams/ton (0.07 ounces/ton) of gold and 52 grams/ton (1.83 ounces/ton) of silver have been treated by cyanide heap leach methods with zinc (Merrill Crowe) precipitation. In approximately three years of operation, the mine has yielded more than 225,000 ounces of gold and over 1.5 million ounces of silver. Currently ore is agglomerated and hauled to the leach pad by truck and is top loaded to produce a 5-meter lift height. Four contiguous reusable (on/off) leaching pads were constructed with an asphalt layer above a carefully compacted sub-base of High Density Polyethylene (HDPE) liner and screened fines. Leach solution of pH 10-11 containing 1.2 to 1.5 gram/liter of cyanide is applied to the heap at a rate of 10 liter/hour/square meter for a total active application period of 30 days. Leached (spent) ore is transferred to the spent ore pile located approximately 1,000 meters to the northeast. The pile currently contains approximately 6 million tons of spent ore. The pile liner, which has been constructed over a prepared sub-grade consists of three geosynthetic layers (geotextile/flexible membrane liner/geotextile). Long term objectives include washing the pile to recover an additional 3 to 4 percent gold and silver.

Jan 1, 1993

By Andrea Brickey, RICHARD AMOAKO, Akshay Chowdu

Production forecasts derived from the medium-term schedule represent the best path forward for underground mining operations to achieve corporate and operational goals. Unforeseen circumstances, such as equipment breakdown, can cause significant deviations from established production forecasts in the short term. Such situations require timely mitigation of the effects of the deviations in order to stay as close as possible to the medium-term plan. This paper presents a deterministic mathematical formulation for short-term scheduling that addresses this challenge. The formulation is able to make up for deficits resulting from operational disruptions by minimizing deviations from medium-term production goals and medium-term activity start dates. We demonstrate this in a case study by simulating disruptions involving reduction in ore extraction capacity and development advance rate. Aside from the rescheduling capability, this formulation can help mine planners conduct analysis on the impact of various disruptions on the schedule. The formulation can help identify those conditions or disruptions that are more detrimental to the achievement of forecast targets, or otherwise. The formulation also affords mine planners the flexibility to prioritize one production goal over the other, depending on operational conditions at the mine. In the future, we seek to incorporate in the formulation respirable dust, diesel particulate matter and ventilation constraints in order to create more realistic schedules, and enhance miners’ health and safety.

Jan 1, 2024

By A. J. Guse

The primary limiting factor for hoisting capacity from great depths is the self-weight of steel wire ropes. Steel wire ropes are very suitable for mine hoisting due to their high strength and durability, but have the negative characteristic of a low strength/weight ratio. Also, as hoisting depths increase, the service life of steel wire ropes decreases due to the higher stresses and physical effects on the ropes. The significantly higher strength/weight ratio of synthetic ropes offers the primary advantage of hoisting a larger payload with a similar size rope and hoisting plant. The beneficial properties of synthetic ropes could be used to improve the overall economics of deep underground mining both for new deep shaft projects and for existing mining operations expanding to deeper orebodies. A research and development program has been initiated to evaluate the suitability of a fully synthetic rope for the mine hoisting application.

Feb 23, 2014

By Earl L. Rau

Although the Sagasca deposit has been known for 76 years, the property was never put into successful operation because of various adverse factors including low market price for copper, legal entanglements, unsuccessful financial arrangements, and an inadequate metallurgical process. Late in 1963, Continental Copper & Steel Industries, Inc., obtained legal control of this property. Since that time there has been a concentrated effort to complete the necessary mine appraisal, process development, and engineering design, and to solve the legal and financial problems to bring this property into production.

Jan 1, 1970

By W. A. Hoyer

Neutron activation analysis for mineral identification has attracted the attention of numerous investigators, judging from the publications on this subject in the past few years. 1-9 The appealing aspect of this method of mineral analysis is its proven sensitivity in the laboratory. In principle, activation analysis is one of the few petro-physical methods whereby a direct analysis for a mineral itself is possible in a borehole. The successful application of activation analysis requires the use of particular neutron reactions, measurement of selected gamma-ray energy intervals, and optimum bombardment and detection times. For copper analysis, Labanov et al., 10,11 using a low-energy PuBe source, reported an acceptable logging means. On the other hand, Pradzynski12, in analyzing ores and process tailings, used high-energy neutrons and photons for surface measurements of process samples. The work of Labanov et al. was based on measuring the rate of decay of the activated copper and hence was not as definitive as might be desired. Equipment is commercially available to carry out activation studies in the field 13,14 Gamma-ray spectra can be successfully transmitted over ordinary logging cables and, with borehole high-energy neutron accelerators and lower-energy chemical neutron sources, a variety of neutron activation methods can be studied. The purpose of the study discussed in this paper was to determine the feasibility and practicability of logging for copper using neutron activation techniques and commercially available equipment. The laboratory study showed that Cu could be detected in rock samples in the laboratory by high-energy neutron activation of 63 Cu. In the field, however, due in part to the large volume irradiated, the direct detection of copper using high-energy neutrons was not as promising. Detection of copper by measuring both the direct gamma-ray emission and the excessively strong low-energy gamma-ray absorption appears promising. Copper was not detected either in the laboratory or

Jan 1, 1972

By Leonard B. Rothfeld

For many years, pulverized coal (PC) boilers in utility power plants have been the dominant market for domestic coal. Today, two new coal utilization technologies challenge the PC boiler's dominance. Atmospheric fluidized bed combustion (AFBC) and "coal gasification/combined cycle" (GCC) stand on the verge of commercial demonstration in the utility environment at a scale of 100 MW. Developed over the past decade, these technologies respond to the demands for cleaner ways to burn coal and for more flexibility in fuel supply. In the near term, these are the "clean coal" technologies most likely to have a significant impact, because they are ready for commercial application. As for environmental acceptability, consider that just a few years ago one of the environmental slogans was "no coal in California." Indeed, the only large quantities of coal above ground in California at that time were in transit on the way to Asia. Today, thanks to new technology, we can point to two operational coal-burning plants in California and one in the works: * Cool Water GCC demonstration plant (100 MW) * California Portland Cement AFBC commercial cogeneration, near Riverside (190 000 lb/hr steam) * Energy Factors AFBC commercial cogeneration at Stockton, to be operational 1988 (44 MW)

Jan 1, 1987

By Stephen P. E. Redmond

A 15 km water supply tunnel is being constructed in Buenos Aires, Argentinata expand the capacity of the existing system. Two 4.3 meter diameter Earth Pressure Balance (EPB) tunneling machines operating at times from the same shaft on a congested work site and advancing through sedimentary deposits underlying this wonderful city pose interesting challenges. As of January 1999approximately 50% of the tunnel has been excavated. Combined machine production rates of 1026 m/month have been achieved. Presentations made in prior proceedings can be referenced for details of the overall Project scope and for details of the tendering process. The purpose of this paper is to compliment those presentations by addressing now the execution of the work.

Jan 1, 1999

By BHAMIDIPATI S. SASTRY, KATTAMURI PAVAN KUMAR, ADITYA PANDEY

Several laboratory methods are available to determine the thermal conductivity of rocks, but most of them are complex and cumbersome. The present study explains the working principle of Lee’s apparatus, which is relatively simple, easy to fabricate and use, and provides consistent results. In the present study, thermal conductivities of sandstone cores obtained from an Indian coal mine are determined using Lee’s apparatus. An approach is discussed to determine the temperature gradient of sandstone specimens while cooling and is used to calculate thermal conductivity. The thermal conductivities of different sandstone specimens have values between 2.37 and 2.59 Wm−1°C−1. For different sandstone cores obtained from the field, properties including specific gravity, specific heat capacity, thermal diffusivity and porosity, along with thermal conductivity, were determined and highlighted in this study.

By Ronald D. Hill

The occurrence of acid mine Drainage (AMD) with coal mining has been well documented. (1) Less documentation is available of its association with other types of mining, e.g., copper, gold, zinc, and sulfur. Yet there are many locations in the western states where acid mine drainage is as great a pollution problem as in Appalachia and in some cases, because of the high copper, zinc, and arsenic concentrations, they present an even more difficult problem. Until a few years ago, it was generally believed that the neutralization of acid mine drainage was uneconomical thus, AMD was allowed to discharge freely into our streams. However, the demand for good water finally dictated that the mining industry be included under pollution laws. In 1964 the Commonwealth of Pennsylvania passed a law requiring that all active mine discharges meet a discharge standard of pH 6-9, iron less than 7 mg/1, and the water must have a net alkalinity. Several other states now require active mines to treat AMD. In all but a few cases, lime neutralization, often in conjunction with aeration, has been the treatment method used. The high cost of lime as compared to limestone and the poor quality sludge, (slow settling, large volumes, and low solids content) has stimulated work in the utilization of limestone. This paper reports on the current state-of-the-art of limestone treatment of AMD.

Jan 1, 1970

By S. C. Suboleski

In a high risk venture such as mining where capital is committed and contracts are signed on the minimum of information, decisions are based primarily on production forecasts derived through consideration of such factors as management-labor relations, mining practice, variations in physical conditions and the equipment applied. Among these factors, the physical conditions offer the least opportunity for control and, due to the wide range of mining conditions that may be experienced, little effort has been made to develop objective methods for measuring their effects on mine out- put. The aim of this paper is to demonstrate a method for assessing these relationships that can be applied under a wide range of conditions both in new mines and in working sections where there is a need to determine the impact of proposed operational modifications. psing empirical data from active underground mines, a mathematical model was developed to derive a set of regression equations for predicting production as a function of mining conditions

Jan 1, 1980

By Muriel S. Robinette

Ground-water contamination from uranium operations could be avoided with proper site analysis techniques. Contamination from tailings disposal sites is carried downgradient within permeable hydrostratigraphic units which can be located and delineated with a combination of drill holes, borehole geophysical logs and surface geophysics. Several case studies are presented to illustrate this application.

Jan 1, 1980

By Ehsan Moosavi, Kamyar Tolouei, Mehran Gholinejad

The literature defines rockbursts in slightly different ways based on their generation mechanisms, field phenomena, and degree of damage, but in a way that is almost consistent. Generally, a rockburst refers to seismic events that mainly happen in underground excavations, for purposes such as underground mining, road and railway tunnels, nuclear power, etc., and that are followed by the collapse and outburst of rocks. Long-term rockburst prediction can be abstracted as a classification problem mathematically, in which we can introduce deep learning to solve it. Further, using deep learning in rockburst prediction can overcome drawbacks such as subjectivity and inconsistency brought from previous traditional approaches. A rockburst data-set, was employed to evaluate the current method for predicting rockburst grade, and the good results of overall success rate were obtained. The results indicated that the proposed algorithms can speed up parameter optimization search, the proposed method is robust model and might hold a high potential to become a useful tool in rockburst prediction research.

Apr 26, 2022

By J. W. Leonard

By using physical and chemical method to increase the bulk density of newly mined coal, the productivity of a mine can be significantly increased. Greater amounts of coal can be placed in fixed volume shuttle car by increasing bulk density. This can increase mine productivity by about 15%. Small, easy to achieve changes in mining operations are required to obtain the increased productivity. This article deals with chemical methods used to increase coal bulk density, the results and discussion are based on experiments performed in the laboratory.

Jan 1, 1992

By R. S. Datta

Regulations on sulfur emissions have caused the electric utilities to evaluate various methods of meeting them. Low-sulfur, low-volatile coals can be burned alone or blended with high-volatile? coals. This option may be a cost-effective alternative to the installation of scrubbers on coal-fired combustion systems. In some blending applications, problems may be encountered because the low sulfur content and high calorific value of the low-volatile or other clean coal allow it to economically upgrade extremely poor quality coal. While this is done to meet specification purposes, actual boiler performance may be dominated by the poorer quality coal. Thus, the reputation of the low-volatile or other clean coal suffers. As a result of laboratory and full scale testing, conducted over the last five years, a model has been developed to evaluate the relative combustion characteristics of various coals and coal blends. A database for different coals has been gathered. This paper presents the model and shows how power plants and coal mine personnel can use it to evaluate their coals from different sources. It can be used to blend two or more coals from different sources so that thee blended coal has flame stability characteristics which are similar to those of the baseline coal.

Jan 1, 1991

By Wolfgang Sand, Alex Schippers, Tilman Gehrke, Thore Rohwerder, Peter-Georg Jozsa

Metal sulfides are degraded via thiosulfate (pyrite) or via polysulfides and sulfur (sphalerite, galena, chalcopyrite) by leaching bacteria The attack on the crystal lattice is either effected by only iron(III) ions or by iron(III) ions and protons, respectively. Consequently, different endproducts are formed. For a control of ARD-processes, these reactions need to be hown to regulate them. Experiments in percolators up to 65 m3 with inorganic compounds like fluoride, concrete, or SDS resulted in differently lasting inhibition. Microcalorimetric measurements of microbial leach activity allow monitoring of these effects with respect to active bacterial cells, and, in addition, the amount or rate of dissolved metal sulfide allowing prediction of possible endangerment by ARD.

Jan 1, 2000