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By Guido Deissnann, Jennifer L. Kirkaldy, Stephan Kistinger, Carol M. Pettit

Contaminated mine drainage presents a potential hazard for aquatic ecosystems and groundwater resources. Reliable predictions of long-term developments in seepage quality are necessary to select reasonable decommissioning options and remediation measures for waste-rock heaps during mine closure and/or mining site rehabilitation to minimize future risks and environmental hazards. Extensive geochemical modeling work was used to assess the consequences of various remediation options for waste rock heaps at a former uranium mine in Eastern Germany. The predicted contaminant discharges are used for an assessment of long- term benefits of decommissioning alternatives to derive conclusions for sustainable remediation measures using risk-based cost/benefit analyses.

Jan 1, 2000

By John R. Marks

Few if any mines in North America have used exhaust air to remove heat at temperatures above the stope reject temperature. In contrast, the South African mining industry has long taken advantage of this heat removal method. The Homestake Gold Mine in Lead, South Dakota, has reached the point where a large air-conditioning upgrade is needed. Since existing air and water resources are being utilized about as well as practically possible, it was recently decided to install an 8.1 MW(R) (2300 ton) plant in the deepest mining division. Two horizontal bulk air spray coolers will distribute the coo1th to active workings via controlled recirculation. The heat will be rejected to exhaust air in four parallel cooling towers. The number and size of these large direct-contact heat exchangers prompted an investigation into South African planning techniques.

Jan 1, 1987

By C. L. Schneider, R. P. King

Size distributions and liberation spectra were measured in samples taken from 10 streams in a taconite milling circuit under normal operating conditions. The size distributions were deter- mined by sieving and the liberation spectra by image analysis using the linear-intercept method with proper stereological correction. The measured data were used to validate a simulation of the milling circuit using MODSIM which included the calculation of both size distributions and liberation spectra. Both the measured data and the simulator showed that liberated magnetite was returned to the mill in the cyclone underflow. The simulation will be used to improve the economic performance of the plant.

Jan 1, 1995

By J. Partyka, J. S. Stachulak

Dust produced during blasting in a copper/nickel based mine was studied and characterized. A stope utilizing the crater blasting technique, or the vertical retreat mining (VRM method), was examined. Two dust monitors were used to measure an airborne dust produced during blasting operations. The data collected in situ was primarily used to formulate the boundary value problem for a generalized equation that describes the transportation process of airborne dust from all places where dust is produced by the VRM mining method. The field data was also used to define the analytical forms for the initial and boundary conditions, to provide a simple and reliable equation for flow of dust in a stope vicinity, and to identify the non-measurable constants. The effects of the amount of blasting material and of the ventilation system in use on dust concentration are also discussed.

Jan 1, 1995

By J. A. Rose, A. S. Atkins

Environmental awareness has become a paramount consideration in the issue of planning and licensing arrangements for the disposal of wastes associated with mining operations. In this con- text the disposal of liquid tailings is a difficult and controversial problem with regard to environmental surface disposal. The paper outlines the use of Information Systems for decision support in the safe and environmental disposal of liquid tailings linked to conventional coarse refuse operations. This offers both an economic and an aesthetic approach to a historical perception of waste tipping in the underground coal extraction industry. The paper will demonstrate a prototype system that incorporates multimedia facilities which include data such as; voice comments, site photography, site plans and fluid flow circuits.

Jan 1, 1996

By S. K. Kawatra, T. C. Eisele

To reduce their sulfur emissions, many coal-fired electric power plants use wet flue-gas scrubbers. These scrubbers convert sulfur oxides into solid sulfate and sulfite sludge, which must then be disposed of. Currently, the major markets for scrubber sludge are for manufacture of gypsum products, such as wallboard and plaster, and for cement. However, the quality of the raw sludge is often not high enough or consistent enough to satisfy manufacturers, and so the material is difficult to sell. Other markets, such as paper manufacture and plastics fillers, have even more stringent quality requirements and will not accept raw sludge at all. In the work described in this paper, several reagents have been examined to determine their ability to selectively improve the flotation of the unreacted limestone contaminant away from the desirable products (calcium sulfite and gypsum). The most success has been achieved using a cationic collector, which shows a higher selectivity between calcium sulfite and calcium carbonate than do the anionic collectors that were studied.

Jan 1, 1995

By R. J. Nankee

Recent on-going efforts to develop commercial coal cleaning beneficiation processes using chlorinated solvents-as the separating media will be described. True heavy media separations were performed on raw coal feedstocks, including Pennsylvania anthracite; Western, Eastern, and Midwestern bituminous; and lignite coals. Separation techniques included bath-type devices, cyclones, and liquid/liquid partitioning. Details on separation devices, removal of solvent, and recovery and recycling of solvent will be discussed. Projected costs of full-scale plants will be given for various coal sizes. A number of the coals evaluated are good candidates for beneficiation using chlorinated solvents. Coal beneficiation is desirable to provide needed coal quality. These needs include low ash fuels for coal water slurries and low sulfur fuels to meet emission regulations. In October of 1985, a paper, "Chlorinated Solvents for Coal Beneficiating"' was presented at the fall meeting of SME-AIME at Albuquerque, New Mexico. It reported the results obtained from various coals as feedstocks and of the separations using chlorinated solvents. These beneficiation results depended on true heavy media gravity and liquid/liquid partitioning separations. This paper will include detailed descriptions of the liquid/liquid partitioning process used in "Dow's Advanced Coal Cleaning Technology?2 and of the "Dow Solvent Recovery Technology.?3

Jan 1, 1987

The heat of immersion of coals in different immersional liquids is measured as a function of particle size and moisture content. Decrease in particle size shows a concomitant increase in the heat of immersion. The heat of immersion is dependent upon the nature of immersional fluids. In addition the nature of moisture present in coal influences the heat of immersion.

Jan 1, 1993

By V. M. Torres

An empirical correlation to detennine laboratory mill grinding time has been developed. Grinding samples to 90 ± 5# below 147 micrometers was required for a flotation testwork at Companhia Vale do Rio Doce (CVRD) Research Center. The initial samples were all below 1 mm in size with different size distributions and work indices (Wi) ranging from 13 to 23 kWh/st. Grinding curves were determined for some initial samples. A correlation was developed between percent retained on 147 micrometers at a standard time and the time required to grind each sample to the required size. This correlation was then used to grind all samples, based on the preliminary grinding model. Finally, a statistical analysis with the size distribution of all samples was performed. The success of using the correlation was confirmed and an equation was determined using the data set.

Jan 1, 1996

By Craig J. Nelsen, David A. Smith

In 1987, LAC Minerals (USA), Inc. conducted a high resolution helicopter electromagnetic (EM) and magnetic geophysical survey on the Ortiz Mine Grant, New Mexico. The primary purpose of this survey was to assist in geologic mapping of a major structural zone, the Tijeras-Canoncito Fault System (TCFS). This structure is a very important ore- controlling feature in the area. Geophysical signatures over known deposits was a secondary goal of the survey, but direct detection of mineralization was not anticipated. The TCFS was revealed to be a complex, branching and anastomosing system of faults which locally form the bounding structures of a graben. The geophysical survey guided subsequent geologic mapping by redirecting field investigations, and geophysically redefining some features which previously had been only partly defined.

Jan 1, 1989

By M. Rossi

The use of service variables in geostatistics (grade-thickness) is common in industry when developing block grade models and geologic resource estimates. This is particularly true in the case of sedimentary and stratabound-type deposits. The approach has proven merits when assessing ore reserves. However, there are cases where its application for preliminary data analysis produces biased estimates. One such case is encountered in uranium disequilibrium studies. This paper demonstrates the inadequacy of service variables when performing uranium disequilibrium studies. Disequilibrium analysis is a necessary preprocessing step when radiation counts are used as raw data to calculate uranium reserves. Typically, a probe is used to obtain the gamma counts from open drill holes. These counts are then regressed (and corrected) against chemical assays obtained from core samples. During this process the grade-thickness variable produces an optimistic image of the relationship between probe grades and chemical (true) grades, causing overestimation of the final geologic resource. The problem is analyzed through a case study.

Jan 1, 1993

By H. Sevim

A new method of designing haulage systems, consisting of belt conveyors and hoists for underground mines is discussed in this paper. Efficient and economic design of such systems will prevent operational bottlenecks and provide savings. The developed model uses a heuristic algorithm to optimize the design parameters and to select the proper equipment specifications. It is a probabilistic model because it considers the probabilistic aspects of face operations. It is versatile because it can accommodate belt conveyor networks of any configuration and hoisting systems that can be either drum or friction hoists for single or multiple-level operations. The model also has the option to internally determine the required capacities of the bunker(s) and shaft- bottom bin. The objective of the optimization process is to minimize the "expected cost per ton of ore hauled" from the working faces to the surface. A numerical example is included to illustrate the capabilities of the model.

Jan 1, 1987

By James A. Jones

The Doe Run Co. emerged from the depressed lead market of the mid-1980s as North America's leading lead producer. Doe Run was lean and mean but quickly recognized that technology had advanced while the company was held to the belt tightening slump. With the 1990s approaching, Doe Run moved quickly to update its technology and control equipment to ensure its position as an industry leader. Doe Run was formed in 1986 when Fluor Corp. and Homestake Mining Co. combined their lead-zinc-copper assets in Missouri to form a joint venture. Doe Run is now owned by Fluor Corp. A rich history of mining, milling and smelting started in Missouri in 1862 when the St. Joseph Lead Co. was founded. Subsequent acquisitions led to the formation of St. Joe Minerals, which was later purchased by Fluor Corp. Six mines, four concentrators and two smelters are presently being operated, and a secondary lead smelter was recently commissioned. The Viburnum, Buick and Fletcher operations are lead, zinc and copper flotation concentrators, while the Brushy Creek plant is set up to process high copper-low lead ores. This article looks primarily at the process control installation at the Fletcher concentrator.

Jan 1, 1991

By Ann M. Hagni

One of the most costly factors in the production of aluminum is the consumption of energy in the form of electricity. Energy consumption is increased as refractories in the Hall-Heroult reduction cells are corroded by penetration of the fluxes cryolite (Na3AlF6) and villiaumite (NaF). To decrease thermal conductivity and refractory waste, protective barrier linings are installed. Dry powder barrier linings form stable reaction products at cell operating temperatures. Four dry powders composed of vermiculite, corundum, wollastonite, and anorthite are characterized mineralogically by X-ray diffraction, reflected light microscopy, scanning electron microscopy, and cathodoluminescence microscopy in this research project.

Jan 1, 1998

By M. M. Rajkovich

Just prior to the close of the century, the Mine Safety and Health Review Commission issued its long-awaited decision in Berwind Natural Resources et al. vs. Secretary of Labor[1] to usher in the new millennium. The case arose as a result of a mine explosion in Eastern Kentucky resulting in the US Mine Safety and Health Administration's (MSHA) issuance of 225 citations, not only to the contractor but to four affiliated entities of Berwind Corp. While an Administrative Law Judge dismissed citations to three of the four Berwind entities, MSHA and the remaining Berwind entity appealed the case to the commission. Although the commission effectively left intact the administrative law judge's decision, it announced a new theory of liability that would apparently be applied in the future, namely the unitary operator theory.

Jan 1, 2003

By S. Subramanian, K. A. Natarajan, D. N. Sathyanarayana

FTIR spectroscopy is used to study the ad¬sorption of an oxidized starch on hematite, corundum, and quart: substrates. The difference spectrum of the adsorbed starch on hematite indicates surface reactions involving -CH2OH and -COH groups and shows striking similarities with that of the ferric-starch system, suggesting chemical interaction between the iron of hematite and the starch adsorbate. The IR spectra of starch adsorbed on corundum and quart: show no evidence of chemical interaction, although hydrogen bonding is apparent. The extent of adsorption of starch on hematite. corundum, and quartz decreases along the series. The evidence for chemical interaction of starch with hematite is further obtained by the X-ray photoelectron spectra of starch adsorbed on hematite, showing noticeable decrease in peak positions of O(Is) and C(Is) of free starch. The Mössbauer spectrum of hematite with stanch adsorbed on it complements these findings.

Jan 1, 1990

By G. Balletto

Increasing environmental awareness leads to a reflection on the consequences of a non-appropriate use of mining resources. In this sense the determination of the mining requirements for the building industry is the necessary prerequisite to activate planning in mining according to the principles of environmental sustainability. Experience shows that there is a relationship between the production of buildings in relation to the shape of the city and the resulting demand for minerals. The increasingly urgent demand for maintenance and restructuring by existing buildings will stretch further the demand for minerals with an excessive, no longer sustainable withdrawal, which will lead to focussing greater attention on environmental policies oriented to the use of alternative materials including materials from recycling. It is pointed out moreover that the joint action of land use planning and mining planning leads to interesting applications that have significant repercussions on the environment.

Jan 1, 2005

By Clark Woodland, William E. Stanley

Mining companies have been required to enter a "new era of management" in the 1980's as they strive to become more efficient in an increasingly competitive market place. One response for many companies has been to modify their mine accounting systems to make them more effective for cost control and decision-making. This paper discusses some of the major issues in developing and implementing a standard costing system as part of improved management reporting and cost control procedures. It describes the key features and benefits of a computerized standard costing system with particular emphasis on budget-setting and variance analysis. It also identifies important factors to be considered in order to achieve successful project planning and Implementation.

Jan 1, 1987

By J. A. Pagliero, R. T. Quiroz, S. H. Castro

Selected voltammograms in tetraborate buffer solutions in the presence of ethyl xanthate or isopropyl xanthate at pH 9.3, for chalcocite, covellite, chalcopyrite, and enargite mineral electrodes, are presented. The concept of critical Eh of dixanthogen condensation (Ehc) is introduced, and the line of Ehc is thermodynamically defined in plots of log [X i] vs Eh, for methyl, ethyl, propyl, and butyl xanthates. A reaction scheme of xanthate oxidation in four steps, involving the dixanthogen condensation step, is proposed. A first attempt to interpret mineral flotation from a more general point of view is made. The electrochemical mechanism of dixanthogen formation and condensation is considered as a particular case of a more general and relevant phenomenon, which is the decomposition of the collector giving hydrophobic colloidal forms, whose associative behavior in bulk solution and at the mineral/solution interface is governed by colloid chemistry.

Jan 1, 1989

By T. M. Campoy, J. R. Jones

When extending the life of an existing mine in Appalachia, it is common to acquire the adjacent reserves and extend the existing mine into it. The existing mine is often renovated to accommodate the new conditions. The existing mining system and the track and belt haulage systems may he modified while the new property is integrated into the old one. All of these changes create new constraints for the mine ventilation system (MVS) that require proper planning and control procedures. This paper presents a study that was carried out for the ventilation system of a newly expanded underground coal mine in the Appalachian region. The process of correcting the ventilation system of the existing mine is discussed. That is followed by a discussion of some of the stages of controlling the expanded system. Numerical data for these steps are also presented.

Jan 1, 1994