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By R. J. Kuczynski

The U.S. Bureau of Mines operated a 2,000-9 (4.4-lb) batch process development unit for recovering platinum-group metals (PGM) from automobile catalysts. Virgin monolith, used pellet and used monolith catalyst samples were tested. Leaching twice with 1-pct sodium cyanide (NaCN) solution at 160' C for 1 h in a pressure vessel dissolved over 95 pct of the PGM from virgin catalysts and over 90 pct from used pellet catalysts. Over 85 pct of the PGM was dissolved from used monolith catalysts when a third leaching step was added. PGM concentrates as metallic powder containing over 99.8 pct of the dissolved PGM and analyzing greater than 70 pct PGM were recovered by heating the pregnant leach solutions from virgin catalysts to 250' C and used catalyst to 275" C for 1 h. The solution after heating contained primarily sodium carbonate from cyanide decomposition and less than 0.2 ppm total cyanide.

Jan 1, 1993

By M. Labrie, H. L. Gibson, G. Doiron, J. J. Watkins, D. H. Watkinson

Abstract -The Corbet deposit is one of 17 proximal Cu-Zn massive sulfide deposits located. within the Noranda Cauldron which occurs within the core of the Noranda Volcanic Complex. The deposit is located at the top of the F1avrian Formation, the lowermost formation of the 3000 m thick Mine Sequence; the deposit has yielded 2.75 M tonnes of ore grading 30Jo Cu, 0.96% Zn, 2.06 g/t Ag and 1.0 g/t Au. The multi-lens Corbet deposit formed within a 250 m wide crater that occurs within a localized breccia pile. The Corbet breccia pile was constructed by explosive magmatic and hydrovolcanic eruptions localized along the south flank of a larger andesitic shield volcano that formed during the waning stages of F1avrian volcanism. The breccia footwall of the deposit allowed unfocused and widespread hydrothermal discharge that resulted in the development of a large area of chlorite and fringing sericite alteration that exceeds, by six times, the size of the sulfide lenses and represents a significant exploration target.

Jan 1, 1993

By Richard Komarek

When limestone (Ca03) is calcined in rotary kilns to produce quicklime (CaO), it is not unusual for 10% to 20% of the stone to abrade and emerge from the kiln as quicklime fines (-6.3 mm or -0.25 in.). While there are various industrial processes that can use fines, handling and shipping is tricky and dangerous. Due to the highly caustic nature of quicklime, airborne dust easily bums eyes and skin. On the other hand, money has already been invested in mining (or buying) the raw material and in the equipment and energy needed for calcining. Discarding the fines will not only waste that investment, but add even more cost in transportation and possibly dumping charges. So the question becomes, how can fines best be turned into a revenue-generating asset? Some plants convert leftover quick-lime fines into calcium hydroxide - Ca(OH)2, also known as hydrated or water-slaked lime - for sale into agricultural applications. For farm uses, hydrated lime fines are preferred over quicklime because they are easier to handle. And they are favored over raw limestone fines for their higher concentration of calcium and greater solubil¬ity. From the producer's viewpoint, quicklime fines are ideal for this use because they go through hydration faster than the larger chunks of quicklime. Those larger chunks, or "pebble lime," are more readily salable and more easily handled, for such uses as steel, copper, aluminum and magnesium production, water waste treatment, chemical, paper, glassmaking and flue gas desulfurization in coal- fired boilers.

Jan 1, 1993

By Filippos Patsiogiannis

Laboratory size (5 kg) aluminum killed low carbon steel melts were desulfurized with synthetic fluxes in zirconia crucibles. The sulfur, oxygen, aluminum, silicon, and manganese contents in the melt were determined as a function of refining time and temperature. With a good argon shield and synthetic flux cover, melt reoxidation was not observed. Sulfur removal followed first order reaction kinetics. The effectiveness of calcia saturated calcium-aluminate (12CaO.7Al2O3) based fluxes in desulfurizing the steel melts was evaluated. The effects of initial sulfur level of the melt, weight of the flux (slag), and additions of tellurium, fluorspar, and barium oxide to the melt on the kinetics of desulfurization were also studied.

Jan 1, 1993

By R. S. Saunders

Congress, under the Nuclear Waste Policy Act of 1982, as amended, charged the U.S. Department of Energy (DOE) with the responsibility for safe and permanent disposal of high-level radioactive waste in a geologic repository. The waste will consist of spent fuel from commercial nuclear generating plants and reprocessing activities. Under direction of this law DOE is currently evaluating Yucca Mountain in Southern Nevada as the candidate site for a potential high-level radioactive waste repository. Presidential, Congressional and State of Nevada approval are needed for repository construction to proceed after successful completion of site characterization and recommendation of the site to Congress. The DOE will submit a license application to the Nuclear Regulatory Commission (NRC) to construct the geologic repository. Following successful construction DOE will update its license application to operate the repository.

Jan 1, 1993

By W. Ellison

Worldwide development of commercial markets for FGD (flue gas desulfurization) gypsum is described and used as a basis for assessing potential overall market growth and regional demand foreseen in the U.S. during the 1990s. Diverse strategies are outlined for cost-effective substitution of this major supply from acid rain control retrofits (power plant scrubbers) for natural gypsum in the principal, existing markets: gypsum board and portland cement. Another focus of utilization forecasting is a key group of related. new-product advancements including floor screeds, mining mortars and various types of innovative construction products.

Jan 1, 1993

By J. R. Evans

Mining claims must have a discovery of a valuable mineral deposit to be valid. When required, a Federal government mineral examiner makes a determination of validity and recommendations thereof to authorized management officials. The examiner should show whether or not an existing mining operation, or a proposed operation have economic viability. This is accomplished through an analysis of legal entities, land status and use, geologic and mineralogic relationships, and mining, milling and processing techniques considered in an appropriate economic evaluation framework. A framework involves market and market entry studies, reserve analyses, all costs analysis, royalty buyouts, tax structure, discount rate of return, and escalation and risk factors. An income approach to value is then used by means of a simple or complex discounted cash flow (DCF) analysis to certify validity. Whether one claim is owned by a single miner, or hundreds of claims are owned by a large corporation, thorough, fair, consistent, and appropriate economic concepts should be applied by the mineral examiner.

Jan 1, 1993

A computer simulation of the automatic control of continuous mining machines has been prepared, similar to previous simulations of longwall mining systems and coal thickness sensors. The simulation allows for programmed variation of the horizon detection method, the azimuthal guidance system, the type and configuration of the miner, varying hardness in the unmined face material (leading to varying error in the machine heading), and the miner's cutting cycle. It simulates control of the miner in three axes. Use of the simulator makes it possible to anticipate problems arising from the complex character of underground mining, which include unpredictable multi-pass coupling and unpredictable variation in geological conditions.

Jan 1, 1993

By David K. Ingram

Research performed by the U.S. insurance industry has determined that mine subsidence is uninsurable. Consequently, the insurance industry has decided not to voluntarily offer mine subsidence insurance. The U.S. Department of the Interior has long been investigating the effects of mine subsidence. These investigations have resulted in Federal regulations and controls of mine subsidence. This U.S. Bureau of Mines report generally describes mine subsidence, the development of mine subsidence insurance programs, and the eight current mine subsidence insurance programs in the United States. The States that have these subsidence programs include Colorado, Illinois, Indiana, Kentucky, Ohio, Pennsylvania, West Virginia, and Wyoming. Major aspects of the programs include history, administrative and operational procedures, insurable structures, recognition of mine subsidence, major exclusions, claims, insurance premiums, and the economic health of each program. Addresses of agencies involved with mine subsidence insurance are also given. Information within this report can be useful for residential and commercial property owners and mine operators. States that are considering starting or have an existing mine subsidence insurance program can also use this report as a model for initiating or modifying their programs.

Jan 1, 1993

By William F. Riggs

The basic theme of this symposium and panel Is Rotation Pads: Are They Optimized? There Is a. reason for phrasing the title In the form of a question. There Is not only the technical competency which we must address; there Is the operating philosophy that must be evaluated on the part of both the customer and the supplier. Customers desire reagents which are trouble-free and capable of providing that extra amount of selectivity or recovery. When they receive ft, after the supplier has provided several years of Internal research, one of the first concerns/complaints Is the price of the product. This has a tendency to rapidly reduce a supplier's support level In the future. Suppliers are equally guilty from another perspective. When they approach a customer to Introduce a product, they often attempt to market by offering only a price Incentive. They then wonder why a customer doesn't respond Immediately to the incentive. They are often oblivious to the fact that the reagent cost is such a minor aspect of the operating budget, and the customer has many more pressing problems on a day-to-day basis In comparison to the reagent cost. We need to establish the understanding that reagent cost Is an Inconsequential cost of operation, and yet has such a disproportionately high Impact on the success of the entire operation. This understanding Is required by both the customer and the supplier. We say to each other,' why are we discussing this since this has been obvious for some time?' The reason is relatively simple in that we talk about it, acknowledge it, and yet we do not adhere to it. The supplier provides a product along with test data containing statistics, analysis, recovery, grade and cost calculations while most of the time ignoring the operating technique which must be applicable In the plant In order to optimize the product. He expects the reagent to be substituted In the plant for the existing reagent and ft works or does not work after trying several variables. The operating management Is equally guilty, In order to best explain this to both the customer and the supplier, ft becomes necessary to review the basic purpose of the major reagents utilized In flotation. A collector is basically to Impact selective, maximum water repellency on the surface of a particular mineral, The frother has the purpose of providing a chemically stabilized membrane on the surface of the bubble at the air-water interphase. This, then, provides a host environment for the attachment of the collector-coated mineral to a bubble. The depressant functions In the reverse of the collector and must demonstrate the same or greater degree of selectivity than expected of a collector. The key area which has been Ignored Is the rate by which these reactions occur and Interrelate. This has a very specific effect on the operating technique and the compatibility of the chemistry, equipment, and the operator himself. Researchers, suppliers, and customers provide reams of data to demonstrate how their products or design produce, for example, higher kinetics, more selectivity, or more recovery. The Information is often true. After all, we are all learned men and laboratory and actual plant data do not lie. However, we must remember the theme of this symposium and panel: Flotation Plants: Are They Optimized? and Optimizing of Flotation Reagents? The direct, honest comment to the two titles is very simple. OF COURSE THEY ARE NOT The plants, equipment, and reagents had better not be optimized or else we are in trouble. The Issue of this panel discussion is to approach this subject from a slightly different or perhaps mainly Ignored aspects of optimizing reagents in flotation. When we have reagents which provide higher kinetics, more selectivity, and better recovery, how do we use them? Since each reagent has a different physical characteristics of froth, rate of recovery, volume effect on the compatibility of equipment, and many more aspects too numerous to mention, the question which has been severely Ignored Is, 'What degree of study and cooperation by both the supplier and the operating management has been conducted In order to prepare the operator for maximizing the performance of a reagent In relation to the rest of the system?" Prior to testing a new reagent, how much time Is spent to bring the actual operator(s) Into the program to make them feel part of the program? How much time is spent explaining to the operator on the float floor how to possibly take advantage of a reagent with faster kinetics or one which Is Inherently more selective? What

Jan 1, 1993

By Orlando C. Rojas

The Potrerillos Smelter commissioned a new El Teniente converter in 1985. As a result of the use of this technology, the Peirce-Smith converters have been processing only high grade matte or white metal. These operational changes resulted in damages to the converter shells, excessive splashing and cold dope generation and very short refractory campaigns. The paper shows the modifications to the tuyere angle, mouth design changes and new techniques for mouth cleaning and gas handling. Operational results up to 1991 are also shown.

Jan 1, 1993

By Zhang Hengzhong

Based on thermodynamics of surfaces and a proposed two-dimensional state equation for surfaces, the relationship between the surface tension (Y) of a solution and the activity (a1) of its component (i) was derived: (1/Y)r2-.¬E (ai/Yl) The derived equation was verified with reported experimental data of water-alcohol systems and water-acetone system, the calculated results showed astonishing coincidence with experimental. Applications of the equation to the five matte systems Cu2S-FeS, Ni3S2-FeS, FeS-PbS, Cu2S-PbS and FeS-Cu22S-PbS also demonstrated that at given matte compositions the calculated surface tensions agreed with experimental fairy well.

Jan 1, 1993

By R. D. Hagni

Pyrometallurgical products from lime roasting of refractory gold ores, pyrite, and arsenopyrite have been examined for their mineralogy, porosity, permeability, retention of contaminant sulfur and arsenic, and potential effectiveness of gold extraction. Cathodoluminescence microscopy, supplemented by X-ray diffraction and scanning electron microscopy-energy dispersive analysis study, has shown that the products phases have characteristic cathodoluminescence properties as follows: anhydrite (CaS04), deep blue; unreacted portlandite (Ca(OH)2), deep purple; oldhamite (CaS), light yellow to rarely pink or orange; a sulfur-rich, arsenic-poor phase, violet; an arsenic-rich, sulfur-poor phase, non-CL. Within the temperature range examined (400-850°C), hematite exhibits greater porosity and permeability at the intermediate roast temperatures of 600-650°C.

Jan 1, 1993

By P. R. Taylor

Three refractory gold concentrates have been tested to evaluate the effect of roasting with hydrated lime followed by cyanidation. The results indicate that it may be possible to roast in such a manner as to contain nearly all of the sulfur, arsenic and antimony in the roaster calcine. Cyanidation results indicate that the gold recoveries are greater than 80% for all three concentrates.

Jan 1, 1993

By N. Edmonson

Apart from its role as an essential input to a wide array of agricultural chemicals and industrial processes, sulfur is interesting in that its supply involves competition between primary product and by-product. This general production structure is found repeatedly among markets for metals and other industrial minerals, and research results from the sulfur market potentially carry over to other markets with similar structures. The purpose of this paper is to present an analysis of the recent and prospective market for sulfur. The analysis will rely heavily on simulation using a comprehensive model of the North American sulfur market developed by the author. A brief description of the model is offered by way of introduction

Jan 1, 1993

By G. D. Hood

The U.S. Bureau of Mines investigated rapid froth flotation through more efficient bubble-particle collisions that improved the overall flotation kinetics. An in-line static mixer efficiently mixed the bubbles, water, and ore, selectively attaching these bubbles to the hydrophobic mineral's surface. As the mixture entered the flotation chamber, the hydrophobic mineral was already attached to the bubbles and was quickly floated away from the remaining ore pulp. The rapid flotation system was evaluated for beneficiation with a western porphyry copper ore containing 0.67 pct copper, and a phosphate-bearing amine flotation tailings sample containing 9.5 pct P2O5 in a quartz matrix. Over 88 pct of the copper was recovered from the ore in a rougher concentrate containing 5.9 pct copper at a rate 7 times faster than conventional flotation. Sixty percent of the quartz in the phosphate-bearing sample was floated at a rate 4 times faster than conventional flotation. The unfloated product retained 80 pct of the phosphate in a l6.9-pct P2O5 concentrate.

Jan 1, 1993

By Best R. J, Poulos H. G

The method for design of primary roof support for the large todoidal cavern constructed to house the Sydney Opera House parking station is presented. The cavern was constructed with 5 m of rock cover beneath Sydney's Royal Botanic Gardens. Design of rock reinfonnent using a combination of fully grouted rock dowels and Macalloy bars was based on control of horizontal shear movement along bedding features in the roof. A combination of linear arch type analyses and non-linear jointed finite element analyses were used in the design study together with an analysis of the shear resistance offered by fully grouted bolts under shear deformation.

Jan 1, 1993

By Y. B. He

The effect of the stability and rheological properties of magnetite dense medium on the separation performance of a 6" dense medium cyclone (DMC) is studied with the use of fine density tracers. The tests in which different size fractions of magnetite are used to prepare the dense media reveal that at low medium densities (<1.5 s.g.), the best separation is achieved when using the magnetite with intermediate particle sizes (du3.2=18 11m). At medium densities above 1.5 s.g., however, it is beneficial to use coarser magnetite. With the fine magnetite dense medium, an increase in medium density results in a decrease in separation efficiency. With the coarse magnetite, an opposite trend is observed; the separation efficiency is improved with increasing medium density. An accurate cutpoint control is critical in gravity separation. The cutpoint shift for coarse feed particles is found to decrease with increasing medium stability (density). It assumes values close to zero in a highly stable fine dense medium. When the size of the treated particles is small (<0.5 mm), the cutpoint shift is mainly determined by medium rheology. With increasing medium density, a continuous increase in cutpoint shift is observed.

Jan 1, 1993

By P. K. Songfack

The transport of slurry within the ball mill depends on the peripheral velocity and porosity of the ball charge. Residence time distribution and mill hold up are of-ten used as indicators of the mode of transport. In this work, the transport problem is tackled via direct simulation of the three dimensional motion of the ball charge. In doing so, the following quantities are calculated: (i) ball size distribution as a function of the distance from the feed end of the mill (ii) mean peripheral and longitudinal velocity and longitudinal velocity of balls of different sizes, and (iii) the spatial distribution of porosity within the ball charge. Hence, the problem of transport is handled as a motion of part of the slurry with the ball charge and part as hydrodynamic flow through the porous structure.

Jan 1, 1993

By Thomas J. Peters

The King Mountain study area is centered about 120 air km northwest of Blackfoot, and 30 air km north of Arco, Idaho. The study area makes up the southern one-third of the northwest-trending Lost River Range--the highest mountain range in Idaho. The area is predominantly underlain by Paleozoic-age marine limestone and lesser dolostone, with a relatively small inlier of silica-rich, Ordovician-age quartzite. There are vast, unquantified resources of these industrial minerals present; however, special markets need to be developed for these resources which are near enough for transportation costs to be competitive. Five prospects were found in the study area; however, only one, the Elbow quartz silica prospect, contains resources and current claims. There has been no mineral production in the study area.

Jan 1, 1993