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By Manuel Gomez

This report presents prediction equations for eleven factors indicative of metallurgical coal quality which have been developed from data obtainable during exploration. Five coke strength parameters and six carbonization product yields have been predicted for coking coals having volatile matter contents in the range 16.3 to 42.1 percent, dry basis. The prediction models developed contain information from the proximate and ultimate analyses, the size consist, and the petrographic composition of coking coals carbonized in BM-AGA retorts at 800°, 900°, and 1,000°C. The equations reported have been evaluated with independent data derived from the 900°C carbonization of 33 binary blends. Present results show that metallurgical coal quality can be predicted ahead of mining. Capability to forecast coal quality is useful in mine planning and should provide basic information for optimization of blending and crushing techniques, leading to the production of uniform coke.

Jan 1, 1968

By Gy. Deák

The Romanian mining industry, especially salt mining, is going through a restructuring phase taking into account the Environment Acquis of the European Union1. In order to preserve the centuries-old salt mines and to develop new ones, in the same salt rock deposit, the long term stability assessment of the saline complex is very important. This case study refers to the Praid salt mine, which includes old salt mines, with impressive sizes, located above the new mines, with activity in progress, in order to provide the means and solutions for efficient conservation and sustainable exploitation for the salt resources. The DKRControl method and FLAC 3D code were used in order to assess the confidence level for the computed prediction of the stability of the salt mine complex salt.

Jan 1, 2008

By C. A. Born

AMAX Inc. climax's mine-mill complex at Climax, Colorado is best known for its molybdenite production: 50,000 TPY of molybdenite flotation concentrate (95% MoS2) from mill heads containing 0.35% molybdenite. Less recognized are the byproducts that are concentrated from the tails generated in the rougher flotation circuit (see Figure 1). Climax recovers a heavy mineral concentrate by passing the rougher tailings from molybdenite flotation over Humphrey spirals (Figure 2a). This concentrate is floated using xanthate at pH 4 to remove sulfides, principally pyrite. The tails from the pyrite float are then cleaned of quartz, feldspar and light minerals by tabling (Figure 2b). Amine flotation follows at pH 1.5 and 75°C to float monazite (Figure 2c). The present circuit at Climax dries the monazite flotation tailings and utilizes high intensity cross-belt magnetic separation Figure 2d) to generate a high grade wolframite concentrate and a low-grade cassiterite product, both of which are contaminated with the mineral brannerite, (UO, TiO, UO2)TiO3. The uranium specifications have recently become difficult to meet due to the increasing percentage of brannerite reporting in the mill feed. A plant is being built utilizing hot sulfuric acid and sodium chlorate to leach this uranium from the monazite flotation tailings prior to their being fed to the wolframite- cassiterite magnetic separators. This modification is the subject of our paper.

Jan 1, 1975

By C. L. Schneider

The calculation of the liberation spectrum in the product from continuous milling operations is a problem of considerable importance and is difficult to solve because the population balance equation must be integrated in two-dimensional space. Complete solutions require the estimation of a large number of parameters unless a structural model of the ore texture can be used. A very simplified textural model based on the use of the modified Andrews-Mika diagram and the PARGEN simulation of multi-phase particles has been formulated and is used to simulate the behavior of a continuously operating laboratory ball mill. A sensitivity analysis for this mill has been done to show the likely effect of model approximations on the predicted liberation spectrum which will be measured.

Jan 1, 1992

By Y. C. Lo

This paper attempts to answer whether or not the mill performance at Bougainville could have, in fact, been predicted by the population balance approach, or whether other special considerations are required to explain their behavior. In recent studies, the plant tests were performed at Bougainville and batch tests were carried out at the Utah Comninution Center. In all tests power measurements were made and several levels of energy input to grinding were evaluated. Also, tracer tests were performed for mill residence time determination. The performance of Bougainville's 5.5 x 6.4 m mill has been very successfully predicted by population balance methods. The prediction errors are only about 1% on product size distribution and 4% on power with a mill volume scale-up of 3790 to 1. It is significant that this approach will reduce the risk of failure in large mill design that has been recognized in traditional methods.

Jan 1, 1987

By William E. Bonini

Gravitational field anomalies have been observed over many igneous intrusives of medium (4000 km2) to small (100 km2) size in outcrop area. These studies give good results because the residual anomalies can be separated from larger scale crustal anomalies and density contrasts usually are present. Although unique solutions are not possible, the analysis of the gravity anomalies can put limits upon the geologic interpretation of such bodies. Three examples in Montana, U. S. A. are discussed: (1) the Boulder Batholith, a late Cretaceous quartz monzonite series of intrusives of 4000 km2 outcrop area; (2) the Little Rocky Mountains, an up-domed area, in which an Eocene porphyry (130 km2) has intruded the Precambrian crystallines and lower Cambrian sediments; and (3) the Crazy Mountains, an Eocene diorite (100 km2), which has intruded the Paleozoic and Mesozoic sediments. In both the Boulder Batholith and the Little Rocky Mountains, intrusive rocks are less dense than the surrounding rocks and negative anomalies are found (40 and 28 mgal, resp.). In the Crazy Mountains, the intrusive is more dense than the surrounding sediments and a sharp positive residual anomaly of 42 mgal is observed. The analyses of the gravity anomalies predict that: (1) the thickness of the Boulder Batholith is on the order of 10 to 15 kms and is concave upward; (2) the Little Rocky Mountain syenite is not a simple laccolith, but is T-shaped and extends in depth to about 16 kms; (3) the Crazy Mountain diorite is not a simple small scale series of stocks, but a large connected body extending in depth 5 kms to the basement (although nothing can be said of it within the basement because there is little density contrast). The analyses of the anomalies place important limits on both the areal and depth extent of the intrusive bodies. Of all possible geophysical techniques, gravity studies offer the most promise in the determination of the shape in depth of intrusive bodies.

Jan 1, 1969

By J. B. Lott

The authors' company has recently undertaken a development programme aimed at exploring the relationships between the variables of greatest importance in the design of mixer-settlers for metallurgical solvent extraction applications. Such applications vary from relatively small scale plants treating copper mine waters, nickel containing effluents, etc., where the total flowrates may be of the order of a few hundreds of gallons per minute, to very large scale plants treating several thousands of gallons per minute of leach liquors containing copper, uranium or other metals. This paper outlines the physical and mechanical factors which must be taken into account when designing mixer-settler systems for large scam. solvent extraction plants. The performance of the equipment will also be dependent upon the chemistry of the system, including the kinetics and thermodynamics of the ion exchange reaction itself, the effect of impurities flocculants, surfactants, temperature, etc., but these will not be dealt with here. Much of the laboratory work has been carried out using copper containing solutions and either LIX 64* or LIX 64N* as the solvent dissolved in various grades of kerosene. For simplicity, all the graphs and tables of results which are presented and discussed here will refer to the LIX-copper system, although the conclusions will in many cases be generally applicable to other systems also. The LIX-copper process is now sufficiently well known to obviate the need for a full description, however, an outline flowsheet of the process is shown in Figure 1. The ultimate objective of a laboratory programme for a particular extraction application is to provide data upon which a mixer-settler system can be designed to handle a given throughput of leach liquor and extract from this liquor the maximum quantity of metal for the minimum cost. In other words, the objective is to determine the design and operating parameters which achieve the optimum balance between capital and operating costs. * Trade-marks for General Mills solvents.

Jan 1, 1971

By W. M. Cross

Optical fibers have revolutionized the telecommunication industry, because of their ability to transmit large amounts of data over long distances. Without optical fibers many of the communication technologies on which business, industry and research rely would be impossible. In addition to their use as communication devices, optical fibers are often used as sensors. Despite the great promise that optical fibers have for the development of many types of remote sensing devices, few remote sensing devices have been built for use in the mineral industries. This paper will describe the use of optical fibers as sensors for surfactant adsorption at mineral surfaces.

Jan 1, 1995

By C. A. Rowland

Introduction Rod mills are horizontal, cylindrical, rotating, tumbling mills in which steel rods, that are usually about 6 in. shorter than the length of the grinding chamber, are used for grinding media. Fig. 33 shows a cutaway view of a rod mill. Rod mills were first used around 1910 because of their ability to grind in open circuit, consistently produce a uniformly sized prod¬uct, give greater continuous availability, and give lower maintenance costs. They have basically replaced roll crushers and coarse grinding ball mills in comminution flowsheets. The present 20-ft limit on rod length, based on rod manufacturing methods, and the pulp flow char¬acteristics, that influence mill capacity, have established the maximum rod mill sizes' of 15 x 21 Vs ft using 20-ft rods and drawing from 2,200 to 2,300 hp. Rod Mill Uses. The principal uses for rod mills are: preparing feed for ball or pebble mills, grinding gravel or aggregates to the size analysis required for making concrete sand, preparing coarse agitator feed for leaching operations, and for primary grinding circuits, particularly in industrial mineral applications. Wet grinding is the most frequently used grinding process for rod milling. There are a few special cases where dry rod milling is used. Preparing feed for ball or pebble mills is the most common use for rod mills. In ferrous and nonferrous ore concentrators, wet open-circuit grinding is used to prepare ball-mill feed. Figs. 34 thru 37 show the four basic grinding circuits used in these concentrators. In rod mill-ball mill grinding circuits, where the rod-mill discharge contains 25% or more of the grinding circuit product-size material, the rod-mill discharge can be fed to the ball- or pebble-mill classifier as shown in Fig. 34. This is the most frequently used rod mill-ball mill circuit in the nonferrous ore concentrators. In a few concentrators such as Anaconda's Weed concentrator,55 the rod mill discharges to one classification stage which makes the same or a slightly coarser particle-size cut as the classifiers used to close the ball- or pebble¬mill circuits, as shown in Fig. 35. In concentrators where rod mill-ball mill circuits are used to grind low grade magnetic iron ores such as Reserve Mining Co., Silver Bay, Minn.; Erie Mining Co., Hoyt Lakes, Minn.; Eveleth Taconite Co., Forbes, Minn.; US Steel, Mt. Iron, Minn. and Atlantic City, Wyo.; Inland Steel-Jackson County Iron Co., Black River Falls, Wis.; and The Cleveland-Cliffs Iron Co., Adams mine, Kirkland Lake, Ont., the rod mills discharge to rougher magnetic separators (cobbers), the concentrates from which are fed to a ball milling stage as shown in Fig. 36. The same basic circuit is also used with gravity concentra¬tion methods such as spirals (Hanna Mining Co., Groveland, Mich.), tables (St. Joe Minerals, Bonne Terre, Mo.), and jigs. When the rod-mill discharge contains less than 25% of the grind¬ing circuit product size, this indicates an ore that does not readily produce the fines needed to help carry the coarse feed into the ball charge. When this occurs, the fines in the rod-mill discharge are needed in the ball mill or pebble mill so the rod-mill discharge flows direct to the second-stage mills as shown in Fig. 37. Rod mills are used to make feed for open-circuit ball mills such as those used in wet grinding cement raw material (American Cement, Brennan Ave¬nue plant, Detroit, Mich., and Port Huron, Mich., plant, and at the South Dakota State Cement plant, Rapid City, S. Dak.). Grinding gravel or aggregates to the size analysis required for making concrete sand is used in areas where natural sand of the proper particle size gradation required to make concrete is not availa¬ble. Three-quarter inch crushed aggregate is ground to 4 mesh using center peripheral-discharge rod mills (Fig. 38) operating in open circuit. US Corps of Engineers specifications state that the sand product be 93-100% passing 4 mesh and contain no more than 3-7% passing 200 mesh. It may be necessary to classify the rod-mill discharge to remove any excess -200 mesh sand produced in the rod mill. Particu¬larly when processing aggregate with high abrasion indices, center peripheral-discharge rod mills are used instead of hammer mills, fine bowl crushers, and crushing rolls for the production of specification sand. If the -4 mesh size fraction of the rod-mill feed is removed

Jan 1, 1985

By V. D. Smar

The flotation process may be considered an interactive system consisting of many chemical, operational, and equipment variables. Changing anyone of these variables causes an overall system response change. This study examines the effects of simultaneously changing the operating variables of: (1) frother concentration and air flow rate, and (2) frother concentration and collector concentration. It is part of a comprehensive study to look at how changes in several of the major variables may be used to produce interactions which will allow the rougher flotation process to be optimized. Ultimate recovery, flotation rate, concentrate grade and froth quality, are used as the major evaluative criteria.

Jan 1, 1993

By P. Semberg, B. Bjorkman, C. Andersson

"In this study, the interaction between magnetite and the additive olivine was studied after oxidation as well as after isothermal reduction at temperatures in the 500º-1,300º C range. In the olivine sample, the forsteritic olivine particles react partly during the oxidation pretreatment to form magnesioferrite and vitreous silica along the particle corona. This breakdown of the olivine particles during oxidation liberates magnesium from the particles, which do not react until temperatures of above 1,150° C in reducing atmosphere. When the hematite in the sample is reduced, and when the temperature is high enough to allow solid-state diffusion at ~800º C, the magnesium of the magnesioferrite redistributes, so that the magnesium concentration approaches the same level throughout the iron oxide structure. For magnetite, this did not occur until 800° C. At 1,000° C, this magnesium reacts further with the silica in the glassy slag phase, which crystallizes into fayalitic olivine. At this temperature, the magnesium has diffused over distances of more than 600 µm from large olivine particles after 2 hrs reduction. From this point, the primary slag phase in the pellet, until melting, is solid fayalite. Upon reduction to metal, the metallization front concentrates the MgO in the remaining wustite, which can lead to MgO levels of up to 10 mole% locally. The melting point of the fayalite is raised from 1,145º C to a melting range of 1,238-1,264º C due to the MgO increase, as estimated based on phase diagrams, which were adapted to the pellets tested. Much of the olivine that remained unaltered in the oxidation process will be encapsulated by iron before the particles begin to dissolve in reducing conditions and, therefore, plays no role in the reduction before final melting of the particles occurs.IntroductionEnvironmental concerns have placed increasing pressure on the CO2-intensive iron and steel industries to further optimize operation toward higher productivity and more efficient use of reducing agents. At the same time, high demand for iron ore has caused new iron ores with lower grades and more complex chemistries to be taken into production. In Scandinavia, the main iron-bearing material is magnetite-based pellets with olivine, which allow operation with very low slag volumes and, hence, lower fuel rate ( Slagnes and Sundqvist Ökvist, 2008; Hallin et al., 1994). Both the MgO and SiO2 of the olivine, as well as the elements of the gangue of the ore, i.e., Si, Mg, Ca, Al and alkali, interact with the iron oxides to give the finished pellet product its final properties in the blast furnace. Tailoring the additive mix to be used for a certain iron ore for optimal product properties, therefore, requires detailed knowledge of the mechanisms by which these elements dissolve and react in the pellet."

Jan 1, 2015

By J. F. Cornelsen

Wheel loaders are currently being used in many mining applications for a variety of reasons. While they sometimes provide the lowest loading cost, a primary advantage of the wheel loader versus other loading systems is the increased versatility and mobility inherent in a wheeled vehicle. The advent of large wheel loaders with much greater digging capability enhanced wheel loader usage in severe loading applications. To match these severe conditions, machines offered today were designed to work in these rocky conditions. Soon after the introduction of large wheel loaders into rocky conditions, however, it became apparent to many users that tire costs could at times account for up to 50% of total hourly operating costs on large wheel loaders. In some applications, tire costs alone pushed wheel loader economics beyond the economic feasibility for these jobs, prohibiting their use. In an effort to combat high tire costs, several attempts have been made to put fast moving steel around the tires to provide a strong interface between vehicle and ground. Some earlier attempts involved wrapping tracks around tires. Mechanical difficulties with these systems limited their customer acceptance. Subsequently, the development of protective tire chains came into favor. While tire chains offered added protection to the tires, the cost and maintenance of the chains remains a problem in 1972, the Dystred arrangement was announced for usage on a 6 cu yd wheel loader from Caterpillar Tractor Co. (See Figure 1). The Dystred offered the advantages of greatly increased tread life over conventional tires, as well as resistance to tread puncture in most situations. The arrangement basically employed a track system similar to that used on track type loaders. Pin and bushing wear often caused high hourly operating costs and excessive machine downtime. In addition, the connection of shoes through the use of links, pins, and bushings forced a limitation on too speed of the vehicle.

Jan 1, 1976

By Z. Yunquan

The flocculation and dispersion behaviors of microsize wolframite and quartz are systematically studied in this paper. For synthetic mixtures, the floc separatory method on gravity units--electromagnetic vibration table (EVT) and lifting column (LC), have been approached. Satisfactory results can be obtained with a weak shearing. A better metallurgical performance can also be achieved for natural ore slimes through the combined technique. The efficiency is better than that of single gravity separation. Finally, the mechanism has been investigated.

Jan 1, 1990

By Kendall Y. Keuhey

The Mercur Mine, developed and operated by Getty Mining Company, is designed to process 3,000 tons/day of gold ore from the historical Mercur Hill mining district. The mill process involves crushing, grinding, and cyanide carbon in leach for recovery of gold ores ranging from 0.08 to 0.10 oz/ton. During the mining of normal grade ore, a substantial tonnage of material containing 0.02 to 0.05 oz/ton is mined and would be available for heap leaching. Also, Getty Mining is developing methods to test and prepare lower grade material for heap leaching by rejecting a course rock fraction from the grinding circuit SAG mill. This lower grade fraction is suitable for heap leaching, and its removal will upgrade the regular mill feed. Other test methods are directed toward leaching techniques on some 4.0 million tons of tailings that resulted from roasting and/or cyanide leaching Mercur ores in the early 1900s. The natural carbons associated with the Mercur deposits require special treatment to reduce their gold adsorption effects when leached with cyanide.

Jan 1, 1983

By R. L. Grayson

Conventional mine safety wisdom states that "the most efficient mines are also the safest." Since the 1980s, small mines (and contractors) have been targeted as the most dangerous ones because of their fatality records. Statistical testing of 1993 West Virginia safety and production data indicated that the most efficient WV mines were not the safest ones, considering correlations between the severity measure and tons per employee-hour, except for very small mines. This paper will present the results of an extended analysis of WV mine safety using 1993 and 1996 data, concluding with the method used to suggest current priorities for focusing interventions.

Jan 1, 1998

By Cyrus W. Field

Metalliferous sediments constitute an important component of the sedimentary veneer that overlies basaltic oceanic crust of the Nazca Plate and elsewhere. Although first collected more than one century ago near the East Pacific Rise during the Challenger Expedition and recognized for their anomalously high content of Fe and Mn, occurring as very fine-grained, yellow-orange, oxides, hydroxides, and oxyhydroxides, it was not until the more detailed studies of Bostrom and Peterson (1966) that their geologic significance and concentrations of other transition metals were fully appreciated. The Nazca Plate is a dynamic lithospheric unit bordered by the Peru-Chile trench and the East Pacific Rise to the east and west, and by the Galapagos Rift and the Chile Rise to the north and south (Fig. 1). Samples employed in this study were taken from piston core recovered from the Nazca Plate (Fig. 2), D. S. D. P. drill core from the northeast Pacific (Dymond and others, 1973), ferromanganese nodules from dredge-haul s at several locations, and from hydrothermal mineral deposits of the Andes. Our efforts have been largely sponsored by the National Science Foundation through its International Decade of Ocean Exploration Pro- gram. The metalliferous fraction of these sediments is widespread, but generally small. Sedimentation is dominated by biogenic silica in the equatorial latitudes, terrigenous debris adjacent to the South American Continent, and by biogenic carbonate elsewhere, except at depths below 3500 m in the central and northwest parts of the Nazca Plate near the East Pacific Rise. Contributions of these distinctive sediment types are shown by the distributions of Si02, A1203, and CaC03 given in Figure 3.

Jan 1, 1982

By Eugene A. Lang

Mr. Chairman, ladies and gentlemen. As a member of the uranium and coal producing community, I am pleased to participate in a session dedicated to a look at these and other mineral markets.(title slide) before sharing some of my thoughts with you, let me tell you a little bit about rocky mountain energy company. It was established as a subsidiary of union pacific corporation in 1971 with responsibility for coal, uranium, and industrial minerals. We participate in four coal mining operations and a uranium mine and mill all in Wyoming, and an aggregate and an abrasive operation in Utah.

Jan 1, 1984

By P. H. Qi

Activated carbon loaded with gold from different halide solutions has been characterized by thermal analysis techniques. The mechanism of gold uptake by carbon varies from predominately adsorption for gold iodide to predominately reduction for gold chloride. TGA and DT A measurements confirm the existence of adsorbed gold-halide species within the micropore structure of carbon. These results suggest that the ration of reduced; adsorbed gold increases for gold halides in the order Au-I > Au-Br > Au-Cl. In the case of Au-I, TA results for the loaded carbon were compared with pure compounds of 12, AuI and AuI3.

Jan 1, 1996

By G. P. Hand

The purpose of this paper is to bring to your attention the various kinds of high performance graphites available today, their characteristics and possible applications. These materials are products of a proprietary high temperature technology developed by Superior Graphite Company. We feel we have only begun to tap the potential of this technology and the utilization of the resulting products. During the course of the paper, we shall investigate high purity, high performance graphites made from raw materials such as mined natural graphites, synthetic graphites and petroleum derivatives. We shall define their characteristics and resulting benefits to current applications, along with applications currently under development. It is our desire to stimulate speculation and development of current high performance graphites and their applications as well as ideas for new high performance products and applications. First, a little background about the process. The technology was developed through a concentrated R&D effort which culminated in 1976 in the construction of a unique furnace capable of continuously processing tonnage quantities of granular carbons at temperatures in excess of 2,500 degrees C. This process is capable of refining various carbonaceous raw materials, including natural graphites, to levels of purity and consistency that were previously unattainable in commercial quantities. Carbon contents in excess of 99.9% are currently being produced on a continuous flow-through basis. Since beginning operation in 1977, this plant, located in Hopkinsville, KY, has been expanded in stages to its present capacity of producing over 45,000 tons of purified graphites and graphitic carbons per year. In addition to the purification process, the technology used allows the introduction of selected elements into the carbon/graphite structure to provide additional benefits. Elements of interest include boron, silicon, copper, iron and rare earths. The characteristics of and applications for some of these products will be discussed later.

Jan 1, 1990

By V. Z. Sun

One of the major concerns of ground control in a coal mine is safety against failure of one of three components (i.e. roof, pillar, or floor) of the mine entry. In order to better design and evaluate stability of the mine entry with a certain confidence, a reliability approach is introduced rather than using the conventional safety factor (SF) method only. Advantages of using the reliability approach is that it not only takes variability of both rock/coal properties and stress distribution into consideration, but also assesses the stability of each component and mine entry as a whole system. Therefore, it is anticipated that, by using this approach, the current ground control technology in coal mine will convey a better sense of confidence. The results of a case example show a significant influence on the current design concept and stability evaluation of mine entry.

Jan 1, 1997