Search Documents

By John W. Cash

The mineralogy and textures of cyclone dust, sludge, and occasional build-ups in the American Iron and Steel Institute (AISI) direct ironmaking pilot plant at Universal, Pennsylvania have been studied by reflected light, transmitted light, and cathodoluminescence microscopy, and phase compositions have been determined by SEM-EDS. The cyclone dust consists of particles of carbon, metallic iron, sulfur-bearing iron, and wustite. Measurements of particles in the sludge indicates that 69% are less than 2.5 um across, 21 % are 2.5-5 um, and 10% are larger than 5 um. Mineralogically the sludge particles are mainly carbon and metallic iron, with minor wustite and sulfur-bearing iron. Build-ups that sporadically develop in the furnace consist of olivine, hercynite spinel, metallic iron, wustite, pyrrhotite, pseudobrookite, akermanite-ferroakermanite and gehlenite. The microtextures shown by the build-ups indicate that much of that material has precipitated at the build-up loci. This study has been supported by AISI and the U.S. Department of Energy.

Jan 1, 1995

By H. Sevim

Long term production planning in open pit mines requires the determination of cutoff grade, mining and milling production rates, mining sequence, mine life, and ultimate pit limits. These variables interact in a circular fashion, that is, the value of a variable can not be determined without the knowledge of the value of the preceding variable in the circle. Therefore, a genuine solution to the problem necessitates simultaneous determination of the variables. Such a solution methodology, comprised of a group of heuristic algorithms and an unconventional dynamic programming algorithm, is described in this paper. The methodology is applied to a small size Western US gold deposit to illustrate its logic and capabilities.

Jan 1, 1995

By Y. J. Zhang

This paper presents the results of a recent study on the development of an in-situ testing method for determining the coal strength in mine pillars. The strength testing is performed in the horizontal holes drilled into the coal rib using the penetrometer. It is a hydraulically powered device that uses an indenter to press the surface of the borehole until the load reaches the failure point of coal. The pressure and the penetration of the loading pin are recorded by the data acquisition unit. The results collected from several coal mines indicate that this testing method is ideally suited for the realistic coal strength measurements. The new testing system not only improves the accuracy of pillar strength determination, but it is more cost efficient than the conventional method.

Jan 1, 1995

By P. A. Christopher, R. H. Pinsent

"The Adanac molybdenum porphyry deposit near Atlin, in northwestern British Columbia, was discovered in 1905. It was explored extensively between 1967 and 1980.The deposit is within a complex, multi-phase, quartz monzonite stock that is a satellite of the post-accretionary, Surprise Lake Batholith. Biotite K-Ar dates range from 703 ± 2.4 Ma to 71.6 ± 2.1 Ma, indicating a Late Cretaceous age of emplacement.The deposit comprises an irregular-shaped ring or halo peripheral to a quartz monzonite porphyry dome, or ""cupola': The shape of the ring, and of a smal~ fine-grained quartz monzonite intrusion, and the presence of higher-grade mineralimtion on the eastern flank of the cupola, suggest partial control by a preminera/ structure. The deposit is truncated by a steep, northwesterly dipping, normal fault (Adera Fault) that down-dropped the northern half of the deposit by a minimum of 100 mThe deposit lacks strong zonal alteration but there are narrow envelopes of potassic alteration around some veins and local zones of intense wall-rock silicification. There is considerable retrograde alteration along postminera/ faults and fractures.Molybdenite occurs in veins and fractures, many of which are relatively flat-lying. They occur in all phases of quartz monzonite. Molybdenum is the only element of economic significance. There are vein and skarn occurrences with tungsten, tin, lead, zinc and precious metals peripheral to the deposit.In 1981, Placer Development Limited reported an ""undiluted mineable mineral reserve"" of 151 971 000 tonnes grading 0.063% Mo at a cutoff grade of 0.04% Mo and a strip ratio of 1.5:1."

Jan 1, 1995

Commodities statistics and other information are available through the following three systems: Internet Access: To acccess the USBM Gopher server on Internet, connect to: gopher.usbm.gov port 70, using gopher client software. Or contact the Systems Administrator for technical questions: Matt Klevemann, 412-892-6499 (klevemmc@miner.usbm.gov) These USBM materials are available on Internet, with more to come in the future: Publications and other research findings, including this bimonthly publications list, newsletters, tech transfer updates, enviromental technology research, health and safety information. USBM software products Media materials and speeches. Mines Data: Computer bulletin board. Log on via modem through 202/501-0373, or call 202/501-0406 for technical assistance. Mines FaxBack. Return fax service. 1. Use the touch-tone handset attached to your fax machine's telephone jack. (ISDN [digital] telephones cannot be used with fax machines.) 2. Dial 202/219-3644. 3. Listen to the menu options and punch in the number of your selection, using the touch-tone telephone. 4. After completing your selection, press the start button on your fax machine.

Jan 1, 1995

By J. G. Pippenger

The Coteau Properties Company's Freedom Mine is a surface lignite mining operation located near Beulah, North Dakota. Coteau, a wholly owned subsidiary of The North American Coal Corporation, produces more than 13.5 million tonnes per year, ranking it among the largest mines in North America. In 1993, Coteau ranked seventh in terms of annual coal sales, becoming the largest mine outside the Powder River Basin of northeastern Wyoming. However, for the Freedom Mine to stand among these Powder River heavyweights, Coteau over-came several obstacles, including a coal seam with three quarters the heating value and overburden to coal ratios three times higher than the Powder River mines. Coteau's ability to compete has been built around a program of continuous productivity improvement, cost efficiency, and innovation. This report highlights a few of the major improvements implemented in recent years.

Jan 1, 1995

By K. Kim

A site characterization strategy formulated for the probabilistic design of underground structures is presented, which takes into account the variability of rock properties and the stochastic nature of the rock failure process. It entails determining probability distributions of rock properties by utilizing the theory of extremes and Monte Carlo simulation. Laboratory and field test data are analyzed and presented to illustrate the methodology. The results indicate that the distributive characteristics of rock mass properties can be estimated using empirical relationships currently available. This results of analyses can be incorporated into the design of underground structures, and then, the relative uncertainties of the failure probability of the structures can be assessed.

Jan 1, 1995

In this U.S. Bureau of Mines report, proposed narrow-vein and longwall mining concepts using drill-split technology (described in part 1 of this series) and in situ liner concepts (described in part 2 of the series) are combined and applied conceptually to environmental problems. Proposed applications deal with (1) acid mine drainage (AMD), (2) solid waste disposal, (3) site remediation, and (4) pollution prevention through innovative industrial design. For control of AMD from abandoned hillside mine workings, it is proposed that source veins be re-mined, processed for residual values, then backfilled using an impermeable compound backfill mix. For solid waste disposal, "vertical landfills" are proposed, consisting of trash-backfilled underground rock quarries. Vertical landfill activities take place in in situ lined containments that geohydrologically isolate the mining-backfilling activities. Site remediation through the creation of in situ underliners, for the capture of toxic leachates, and pollution prevention through the underground storage of toxic, flammable, and explosive materials in in situ containments, are proposed.

Jan 1, 1995

By Satya Harpalani

The four most important parameters controlling the flow of gas in coal are the gas content, permeability, diffusion coefficient and cleat characteristics. Estimates of these and, more importantly, a knowledge about the variation in their values over time are required for simulation of long-term gas production. This paper describes experimental techniques to determine each of these, along with their time dependency, under simulated in situ conditions. It is shown that the permeability, diffusion coefficient and the cleat aperture values are not constant as usually assumed to be. There is a significant variation in their values as a result of changes in the microstructure of coal associated with release and flow of gas.

Jan 1, 1995

By C. Woofter

Quarry operators must continue to change and adapt environmental compliance methods to meet the increasingly demanding regulations. To fulfill industry needs, a computer-based decision support system is being developed to facilitate decision making that mine operators are required to make regarding environmental responsibilities. This system can help to determine permitting and compliance measures needed for air, surface water, groundwater, noise, aesthetics, vegetation, wetlands, hazardous wastes, storage tanks and wildlife habitats during the development, operation, and closure phases of mining. Operators will utilize the system's user-friendly interface consisting of mouse driven responses and limited keyboard entries on a desktop computer. The system is easy to upgrade according to the user's needs and changes in current laws and regulations. Data input models, user interfaces, and support of decision making are explained. The program permits inclusion of the decision maker's own insights through "what-if' analysis, in which the user can change ad hoc entries and check the related consequences. Using this approach, the user has complete control over all steps of the decision making process. A storm water example is selected to demonstrate the potential benefits of the support system to environmental decision makers.

Jan 1, 1995

By R. A. Ynchausti

In January 1993, Pyramid Resources began implementation of a supervisory expert control system at a U.S Cu concentrator. The objective of this control system was to improve plant profitability through unit operation optimization and integration. This paper documents the key aspects of the project, including: economic and associated benefits, system architecture, concepts of implementation, process control strategies, practical aspects of implementation and conclusions. The implementation of expert control at this concentrator has resulted in an estimated benefit of $50,500 per day. This is a net result of improved tonnage, reduced reagent consumption, improved concentrate grade and reduced energy per ton produced.

Jan 1, 1995

By Daniel S. Gwinner

The tolling, or processing for a fixed fee, of aluminum drosses to recover the metal units is a common practice in the Aluminum Industry. The Dross Toller is acting for the owner, and since most dross processes result in material going to landfill, it is important for the owner of the dross to insure that the toiler is processing the material and handling waste disposal in an environmentally responsible manner. The paper discusses the Dross Toiler Audit Program, first from the Reynolds Metals Company perspective. Included are the reasons the company deems it necessary to audit and a description of the items covered during the audit. Finally, there will be a discussion of the audit from the Tollers perspective - what the Toiler can expect when the auditor arrives.

Jan 1, 1995

By D. A. Meyer

The long and arduous process of bringing aggregate produced in Mexico to the Gulf Coast of the United States really began in the 1970s when the first exploratory trips were taken by Vulcan's geologists. It was not until the middle of the 1980s that all of the elements of the project seemed favorable and the largest capital investment in Vulcan's history was given the green light. The history of the project will be covered along with a discussion of the role that market forecasting played in the process. Is this the first of many or a once in a lifetime project? In July 1987, Vulcan and its joint venture partner broke ground in Mexico for a world-class limestone quarry and crushed stone production facility. This project is the largest ever undertaken by Vulcan's Construction Materials Group, with a total cost of over 200 million dollars -a cost shared equally by Vulcan and its joint venture partner, Ingenieros Civiles Associados, or ICA, a diversified Mexican company which is also the largest construction firm in Latin America.

Jan 1, 1995

By Jr. Gabler

Because of concern over the availability and reliability of an uninterrupted supply of manganese and other materials, the U.S. Congress requested that the U.S. Bureau of Mines (USBM) study the /low of strategic and critical materials in the economy to delineate and quantify the production areas where metal values are lost. As a result, the USBM developed a generic computerized commodity flow model that is readily amenable to updating. The original model developed for cobalt, with slight modifications, was used to track the flow of manganese. This report follows the flow of manganese through its metallurgical and chemical applications and highlights areas where significant losses occur owing to downgrading, export, or disposal. The study indicates that materials containing 695,000 short tons (st) of manganese were consumed domestically in 1990. Scrap recovery specifically for manganese recycling was insignificant. However, considerable manganese was recycled through processing operations as a minor component of ferrous and nonferrous scrap and steel slag. The major loss category is manganese lost in steel processing, 323,156 st or 46 pet of the 1990 apparent consumption. Most of this loss reports to steelmaking slags. Recovery from slags is technically feasible, but is not economically feasible.

Jan 1, 1995

"The Crescent, DM, and Pothook zones are copper-gold porphyry deposits which formed in association with alkalic intrusions of the early Jurassic Iron Mask batholith. The characteristics of the Crescent and DM deposits are nearly identical. Both formed along the contact between the Cherry Creek monzodiorite and Pothook diorite phases of the batholith. Permeable intrusion breccias along the contact concentrated the flow of hydrothermal fluids. Early, pre-ore alteration is represented by pervasive, sulphide-barren potassium metasomatism. The precipitation of copper-gold ore occurred during subsequent fracture-controlled potassic alteration, and is most strongly developed in chlorite-sulphide veins and their alteration envelopes. A central zone of potassic alteration is surrounded by a propylitic, pyritic halo in both deposits. The DM zone is unique among alkalic porphyry deposits in its high abundance of quartz-sulphide veins.The Pothook deposit formed at the westernmost contact of the Iron Mask batholith with enclosing Nicola Group volcanic rocks. Pervasive potassium metasomatism, similar in style to that at Crescent and DM, is associated with intrusion of the Cherry Creek monzonite. Pervasive and fracture-controlled albitic alteration is associated with intrusion of the Sugarloaf diorite and introduced minor copper-gold mineralization. Most of the copper-gold mineralization was introduced during formation of veins and breccia matrices dominated by magnetite/hematite and sulphide. Late-stage chlorite veining may have remobilized or introduced additional gold mineralization.Copper and gold assays in the Crescent deposit are well-correlated and have a nearly constant Cu:Au ratio, suggesting that the metals coprecipitated during a single hydrothermal event. In the Pothook deposit, copper and gold do not correlate closely, lack spatial correspondence, and suggest that transport and/or deposition of the two metals were not identically controlled and that they may have been introduced at different times by separate hydrothermal events."

Jan 1, 1995

By Hal dun Kurama

In thus-study, Bigadic upper zone zeolitic tuff, which contains about 87% clinoptilolite was used as an ion exchanger for removal of Pb++, Cu++, Cd++ and Hg++ ions from wastewater. Bench scale experiments with two different glass columns, were carried out continuously under the closed/ open circuit conditions. Before ion exchange tests, zeolite samples were treated with NaCI (6ml/ min. and 42BV). The effects of particle size, bed volume, pH and flow rate on the ion exchange capacity were determined. Under the best operation conditions, the effect of initial influent solution concentration on ion exchange selectivity was tested. As a-result, it was found that the Bigadiç clinoptilolite had the following ion exchange capacities;

Jan 1, 1995

By Roy J. M. van Lier

In industrial aqueous solutions, germanium generally occurs in trace amounts amid high concentrations of other metals, such as zinc, copper and iron. Separation of germanium from these metals as well as its isolation from gallium and indium pose a real challenge to the hydrometallurgist. After a brief discussion of the aqueous chemistry of germanium, this paper reviews the flowsheet of the Apex Mine in Utah. The Apex property was the only mine in the world to be operated primarily for production of gallium and germanium, but apparently closed due to great operating difficulties. Several process variants proposed for the treatment of the Apex ore, including bioleaching methods, are addressed. Following a more general description of the behavior of germanium in hydrometallurgical zinc processing streams, available technology for its recovery from aqueous solutions is summarized. Precipitation, solvent extraction, ion exchange, electrowinning, ion flotation and liquid-membrane separation are all outlined in terms of the aqueous chemistry of germanium. Finally, the production of high purity germanium dioxide and metal is briefly discussed

Jan 1, 1995

By C. T. Philipp

Recycling of waste is much preferred over disposal. This paper discusses the Enviroscience, Inc. (ESI) process, now being commercialized by MetWool, Inc., to recycle hazardous wastes using an extractive metallurgical process which is followed by vitrification of non-reducible metal oxides. In this process, volatile and reducible metals are reclaimed as their respective oxides and elements.

Jan 1, 1995

By F. Seymour

A dynamic programming algorithm is presented that takes a series of nested phases, a fixed mining rate schedule, a fixed plant production capacity schedule, and finds the mining and cutoff grade sequence that maximizes the Net Present Value. This tool allows the Mining Engineer to quickly look at project sensitivity to various production capacities, commodity prices, and costs. A description of the algorithm is given along with examples of how it has been used at Newmont.

Jan 1, 1995

By J. T. I. Poijärvi

Outokumpu Harjavalta Metals Oy operates copper and nickel smelters, three sulphuric acid plants and nickel refinery at Harjavalta and copper refinery and precious metal plant at Pori. The by-products of these plants are presented in this paper. The by-products of the smelters include products from slag cleaning of flash smelting furnaces and converters, flue dusts and smelter off-gases. Weak acid and sludges from cleaning of smelter off-gases and acids are the by-products of the acid plants. The by-products out of the copper refinery are crystallized metal sulphates and sludges from electrolyte purification, on which a co-production process of the copper tankhouse is based. The main by-products of the precious metals plant are products from anode slime treatment and platinum metal group concentrates in the recovery of precious metals. Sludges from nickel matte leaching and precipitates from solution purification are the by-products of the nickel refinery. The formation, treatment and processing as well as the research work done for the utilization instead of dumping of the by-products in the production of copper and nickel will also be discussed in this paper.

Jan 1, 1995