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By Vincent Castronova, Jane Y. C. Ma, Joseph K. H. Ma, Chang-geng Mo, Carl J. Malanga

A group of bisbenzylisoquinoline (BBIQ) alkaloids has been shown to exhibit various degrees of effectiveness in preventing silicainduced fibrosis in animal models (1, 2). The capability of these drugs to interact with phosphatidycholine vesicles and rat alveolar macrophages was studied using fluorometric and equilibrium dialysis methods. The lipid binding affinity of these alkaloids was found to depend upon several structural factors including hydrophobic substitutions, the chiral configurations, and the double oxygen bridge-restricted conformation of the benzylisoquinoline moieties. Tetrandrine, which is highly effective in preventing fibrosis, showed strong binding to both lipid vesicles and alveolar macrophages. In contrast, curine and tubocurine, which have little or no effect on silicosis, exhibited only weak binding to lipid vesicles and almost no binding to cells. The moderate binding affinity of fangchinoline to vesicles and cells corresponded to a moderate effectiveness of the compound as an antifibrogenic agent. Methoxyadiantifoline, an alkaloid of unknown antifibrogenic potential, also exhibited high binding affinities for lipid and cells. In summary, this study indicates that alveolar macrophages exhibit large binding capacities for certain members of the BBIQ alkaloids. A positive correlation was observed between binding affinity to alveolar macrophages and the reported antifibrotic potency of these compounds, suggesting that the ability of these drugs to interact with alveolar macrophages may be a key step in inhibition of the progression of silica-induced pulmonary disease.

Jan 1, 1991

By F. Seymour

A modified three-dimensional Lerches-Grossmann (LG) graph tree algorithm that generates the complete set of nested maximum valued pits in a single run is presented. This modified LG algorithm looks at the relative strength (average value) of the branches (groups of blocks). Pointers are allocated and pruned until there are no members of weaker (lower average value) branches overlying members of stronger (higher average value) branches. The final set of strong branches arc listed in order of decreasing strength. The pits they represent form the maximum valued convex hull for a single-variable pit-limit parameterization. A description of the algorithm is given along with examples of lion it has been applied at Newmont.

Jan 1, 1996

By G. Kazonich, S. L. McGill, J. W. Walkiewicz

Naturally occurring minerals and reagent-grade compounds were tested to determine their receptivity to microwave heating. The maximum temperature achieved for the samples and the time required to reach temperature are reported. A description of the microwave oven and a thermocouple technique that accurately measures and continuously records the temperature of samples during irradiation are reported. Extractive applications using the generated microwave data were investigated. Stress fracturing at mineral grain boundaries in a gangue matrix was shown. This should significantly affect grinding energy requirements and liberation properties. A method to produce a magnetic phase on pyrite surfaces, a method of using microwave heating to retort cinnabar concentrate, and a roast-leaching microwave treatment of chalcopyrite ore are described.

Jan 1, 1987

By S. Serata

Background Results of the above study in the August 1991 issue of Mining Engineering offer valuable lessons in the solution of cutter-roof problems. The original study plan was initiated by the discussion authors to solve the problems using the "stress control method" of mining (Serata 1976,1982; Serata, Carr and Martin, 1984; Serata and Gardner, 1986; Serata, Gardner and Preston, 1986; Serata, Gardner and Shrinivasan,1986; Serata and Kikuchi, 1986; Serata, Preston and Galagoda, 1987) However, the plan and the planner were changed to the arrangement reported in the paper. The change was considered reasonable at the time due to the mine engineers' uncertainties about the stress control method. Consequently, the basic principle of the study was shifted from the original stress control method to the method described in the paper, which will be called the "yield pillar method" for the purposes of this discussion. The paper convinces the reader that the yield pillar method fails to solve the cutter-roof problems. This doesn't mean that the stress control method also fails. Actually the contrary is true, as discussed below. Limitation of the yield pillar method The paper illustrates clearly how poorly the yield pillar method performs in solving the problem. The reason for this failure is the lack of the protective stress envelope needed to stabilize the cutter roof. Unfortunately, the protective envelope cannot be formed properly without utilizing the stress control method of mining. Changing the pillar size does not make much difference in the roof stability.

Jan 1, 1992

By W. J. Cieslewicz

Geologically, northeastern Siberia is a region occupied by a folded belt of Triassic and Jurassic sediments and volcanics. Gold mineralization is of Upper Jurassic age. Most of the stream placers formed during the Quaternary. Placer gold was first discovered in 1916. Between 1930 and 1957, mining was carried out by the "Dal 'stroi," a Russian concentration camp organization. Since 1966, the mines have been worked mechanically. About 10 mining districts are now active, producing, altogether, 110 to 135 t (120 to 150 st) of gold annually.

Jan 1, 1987

By J. P. Allen, D. A. Rice, H. L. Abercrombie

Cobalt, nickel and manganese can be recovered quickly, cleanly and selectively from cobalt-rich manganese ocean crust by leaching in dilute acid solutions in the presence of hydrogen peroxide. Common selective precipitation methods can then be used to recover these metals from the leach liquor. The leaching reaction produces only oxygen as a byproduct, and the waste residue from leaching was tested and found to be nonhazardous under existing EPA specifications. The leaching process is effective in either fresh water or seawater. This research is a part of the Bureau of Mines program to identify the mineral resources of the Exclusive Economic Zone and devise methods, for recovering their valuable components.

Jan 1, 1992

By L. A. Puchkov

The creation of automatic methane concentration control systems presupposes the use, as a control factor, of the air rates in workings and in mine as a whole. These systems present a complicated set of computers and software, including as major components the following - systems for detecting methane concentration and air rate; - telemechanics systems; - programs and means of data processing; - programs and means of air rate control in workings and main fan capacity control. The paper analyses the experience of development and exploitation of automatic methane control system in gassy mines of the USSR Donetz coal basin. Much attention is given to the study of technological factors influence upon aerogasdynamic process using automatic methane control system.

Jan 1, 1989

By G. R. Wheeler

Epithermal gold exploration in the last decade has developed useful models for exploring previously overlooked ore districts in Oregon. In eastern Oregon, disseminated gold occurs in epithermal deposits that have been pervasively silicified and brecciated. Many gold prospects staked since 1980 are in fluvial and lacustrine sandstone and conglomerate deposits. Clay alteration products and disseminated pyrite may be present. Vein filling calcite and thin to thick quartz veins are common. Late stage quartz forms pseudomorphs after calcite in many prospects. Arsenic, mercury, and gold are geochemically anomalous but silver is usually not. The epithermal deposits are located in part of the Deer Butte formation or equivalent units. Exploration criteria include the presence -of Deer Butte formation or equivalent units and northwest structures cut by north-south basin and range structures.

Jan 1, 1987

By Chapman Young, Donald E. McCarthy

Many hard rock tunneling projects, where the majority of excavation can be accomplished with TBMs, will still require considerable specialized excavation which can not be done with a TBM. This secondary excavation, involving cross cuts, galleries, flattening of the invert, increases in bore diameter, et cetera, may be accomplished with conventional drill and blast, applied on a small scale and usually with fracture control techniques, or with mechanical splitters. The problems of using explosives in many of these cases and the high cost of mechanical splitting excavation make the consideration of other approaches attractive. The PCF rock excavation method, which has recently been reduced to commercial practice for mine-development excavation, offers an attractive alternative to drill and blast and mechanical splitters. With the PCF method the rock is excavated utilizing a small-charge, propellant-driven, controlled, penetrating-cone fracture process. Excavation is carried out continuously by combining the PCF hardware with integrated mucking capabilities on a carrier which remains at the excavation point. In addition to the benefit of providing for complicated excavation geometry, the PCF method also causes minimal damage to the remaining rock which will significantly reduce ground support requirements. In very bad ground, the continuous nature of PCF excavation allows ground support to be applied as limited sections are exposed thus reducing both the duration and extent that the ground would be free to move. Data on PCF excavation parameters, as measured in actual mining operations, indicate that crosscuts, galleries and the like could be excavated at considerable cost savings compared to drill and blast or mechanical splitters.

Jan 1, 1995

By S. Mathur, Pradip

Polyacrylic acid (PAA) was evaluated as a selective flocculant for the dolomite-apatite system. PAA with a molecular weight (MW) of 4 million was found to flocculate both dolomite and apatite. However, the flocculation behaviors of dolomite and apatite were significantly different with 450,000 MW PAA, which was found to be the lowest molecular weight fraction capable of flocculation. In single-mineral tests with a dosage of 2 kg/t PAA, 90% of the dolomite and 35% of the apatite flocculated. Selectivity was achieved in mixed mineral tests. From a feed consisting of an 80:20 mixture of apatite and dolomite, respectively, a concentrate containing 90% apatite was obtained with a 70% recovery. The dolomite rejection was about 75%, which corresponds to a 2% MgO content in the concentrate.

Jan 1, 1997

By V. Roze, M. E. A. Robertson, C. J. Sharland

Current Techniques - Fire Assay Fire assay of gold has been used for several thousand years and is a well known technique to the traditional assayer. Very few assayers wish to use the method but to date there has been no viable alternative. Fire assay is expensive in labour, time, capital and running costs. Workers can be exposed to hazards and uncomfortable working conditions such as lead fumes, heat stress, dust and eye strain. The high capital cost of putting up the building and equipping it, together with running costs which increase annually at a prohibitive rate makes the technique less attractive each year. The main requirement in most assay laboratories is to maximise throughput economically. This is difficult with fire assay as it is impossible to automate. Each sample for analysis is handled by at least 12 people and each person represents a potential source of error. Record keeping and report generation has to be done manually which is both slow and prone to errors. Replacement of staff requires a considerable training period and with a large turnover of personnel this presents yet another problem. The presence of silver and dross in the gold sample affects the accuracy at low gold values. X-ray fluorescent analysis Two methods of XRF instrumentation have been used with limited success. The first type is a laboratory instrument employing L X-rays. Small samples of a few grams, which are not representative,

Jan 1, 1988

By Yan. T. Y.

Uranium precipitation from an eluate using hydrogen peroxide has been studied in a laboratory continuous unit. The important process parameters were the dosage of H2O2, reaction pH and chloride ion concentration. In the process, the alkaline eluate is acidified to a pH of 2, then H2O2 at 110%-130% of the stoichiometric requirement is added, and finally NaOH is added to maintain a pH of 4 for one hour to complete the precipitation and settling. The chloride content in the system is controlled to 50g/L or below by rejecting part of the decant solution. The process has been successfully employed in commercial operations. The uranium recovery is complete, while the precipitate settles rapidly and can be processed to high purity yellow cake without filtration.

Jan 1, 1991

By Otis M. Clarke

The 34th Forum on the Geology of Industrial Minerals gave members a chance to see the geology of various stone and ore deposits displayed graphically in quarry walls and also provided an opportunity to hear and see first-rate papers and posters on the geology of industrial minerals. Also, some field trips passed through areas of spectacular scenery. As a bonus, participants saw scenic mines, some of which are "pretty as a picture." Watercolor paintings prove it. At the Oklahoma Forum, the writer displayed a number of paintings of mines and other landscapes seen during previous Forum trips. These paintings and this brief article are part of a crusade to prove that some mines and geologic vistas are scenic wonders and belong in our visual heritage. It is a plea to save some of our best geologic exposures for future geologists, tourists, and artists.

Jan 1, 1999

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

Although column flotation is known to be more effective than conventional flotation for cleaning fine coal, little attention has been paid to the considerable sulfur removal potential of this process. Whereas conventional flotation can only with difficulty remove pyritic sulfur from coal, flotation columns can make this separation readily due to their greater selectivity. This project has used a modified flotation column to remove pyrite from fine coal. This column has been shown to be capable of removing 70 to 85 percent of the pyritic sulfur from coal while recovering 80 to 85 percent of the total calorific value. However, the remaining pyrite is too finely disseminated to be readily removed by physical means. Currently, experimentation is in progress using bacterially-catalyzed dissolution of pyrite in acid solution to remove ultrafine pyrite and aid in the removal of coarser pyrite inclusions.

Jan 1, 1988

By S. M. Hsiung, Wen H. Su, Syd S. Peng

This paper examines the interaction problems of multiple seam mining by combining underground investigation, laboratory testings, and numerical modeling. One case of multiple seam interaction that occurred recently in West Virginia was carefully studied. Causes for the interaction problems were identified and the corresponding mining recommendations were proposed. The principle of pillar columnization and the effect of a remnant pillar on mining operations in the underlying and over- lying seams were also carefully examined. Considerable attention was given to the effect the pillar size, the pillar width, the coal stiffness, the extraction ratio, the degree of inhomogeneity in the interburden, the overburden thickness, the mechanical properties of the interburden rocks, the strata inclination, the interburden thickness, and the in-situ horizontal stresses have on the pillar load transfer mechanism.

Jan 1, 1986

By V. G. Matziaris

The differentiation between saturated and un-saturated soils becomes necessary due to basic differences in their nature and engineering behavior. The most important difference is the existence of a suction zone, above the water table, in unsaturated soils. Pore water pressure in this zone is always negative and the shear strength is greater than the one in saturated soils. This is due to an occasional and apparent component in the Mohr-Coulomb equation, which appears in unsaturated soils. In slope stability analysis of unsaturated soils, the factor of safety increases due to this occasional cohesion component of the shear strength. However, the suction zone tends to disappear because of rainfall. In these cases the factor of safety decreases and eventually the slope may fail. In this article, a parametric study of the effect of suction zone fluctuation due to precipitation in slope stability is examined. For this purpose a Combined Hydrology and Stability Model (CHASM) has been applied.

Jan 1, 2005

By G. L. Bloomsburg, E. G. Zahl

INTRODUCTION During the past decade, disposal of mine and mill waste material has become an increasingly important issue. Problems of structural stability and seepage effects on stability have been well addressed, and significant technological advances have been achieved [(1-4)]. The primary problem currently facing industry in the waste disposal area is environmental protection. The greatest environmental concern is over the amount of seepage or leachate entering the ground or surface water systems. Methods to determine the quantity of water seeping from a tailings pond have also been covered in the literature [(5-23)]. However, much further work is necessary to fully implement these techniques to evaluate tailings pond performance and accurately predict the various influences of disposal management on seepage from mill tailings. This study is an effort to develop those necessary techniques. The partially saturated method of analysis which is discussed here is applicable to most situations involving seepage from waste piles. In a conventional type of tailings pond, a slime layer is ordinarily built up under the ponded area. This material will consolidate slowly from capillary pressures and the weight of material deposited above it. In situations where this consolidation results in a slime layer of lower permeability than the native foundation soil, a partially saturated flow condition will usually exist in the native soil. This will result in a smaller quantity of water entering the ground-water system than would be predicted by saturated flow analysis. The finite-element program used in this study was originally developed by Neuman [(17)] and is called UNSAT2. The program will analyze problems of saturated or unsaturated, steady or nonsteady flow and can be used with a variety of boundary conditions such as constant flux, constant pressure, maximum flux, minimum pressure, and with infiltration, evaporation, and seepage surfaces. The maximum conditions are controlled by exterior factors such as atmospheric conditions; but the actual flow in the porous media is determined by properties of the porous media. In this test, the computer code was used

Jan 1, 1980

By Markku Virtanen, Pertti Koivistoinen

From the perspective of a large mining company the comminution circuit design is worth keeping within the boundaries of the organisation. The correct circuit design begins from the understanding of the role of grinding. Grinding is a link only in the long "comminution chain," starting from solid rock and ending at the concentrating stage. The final target in comminution is to take a part in the maximization of Net Smelter Return, which goal provides the simultaneous considering of capital costs, operating costs and the economic effect of process results. As a general rule there will be a single crushing stage only, ahead of the grinding process. Grinding does not use any metallic grinding media at all, and there will be fine crushing for critical material in the grinding circuit. Grinding has a minimum two stages, besides, at many concentrators middling products and quite often also tailings are reground.

Jan 1, 1997

By Murat Budakoglu

Albite (NaA1Si308) is one of the important raw materials for the rapidly developing Turkish ceramic and glass industry. Prior to 1980, development of the ceramic industry in terms of raw material was dependent upon small-scale mining operations; in the last decade, these efforts have increased substantially. The aim of this study is to investigate the geochemical properties and distribution of albite occurrences in the Kocayayla district, which is about 12 km northeast of the town of Milas, about 50 km west of the city of Mugla in southwestern Anatolia. Kocayayla is also well known for its famous ancient city, Labranda. The field area is located in the Menderes Massif, which was formed by major tectonic events during the Late Proterozoic and subsequent periods. The target area was studied to prepare a detailed geological map (scale, 1:10,000), and to determine the formation of albite-mica-schist-quartzite borders in the host rock gneiss. To do this, systematic sampling of albite was done in the two main areas, the Sarikaya and Yumruta? regions. In the study area, albite zones are scattered within an area of about 20 km2, and they extend in a northeast-southwest direction; mica-schists and quartzite veins accompany these units. Mineralogical observations show that quartz is the main mineral associated with albite. In the ceramic industry, the albite + quartz assemblage is well known and is classified as "standard" or "super type," depending upon the content of TiO2 and Fe203. In this study, the Sarikaya albites (profile I) exhibit remarkably lower TiO2 (0.15% on the average) values contrasted to that of Yumruta? (profile 11; 0.24% on the average), whereas Fe203 values vary slightly from 0.076% to 0.085% in both regions.

Jan 1, 1999

By J. Donald Rimstidt, Jeanette K. Jerz

Acid mine drainage is a major environmental problem worldwide. A key to remediating this problem is understanding the rate and mechanisms of the complex, multistep pyrite oxidation reaction under geologically relevant conditions. Because many waste piles are not submerged, a large amount of pyrite oxidation actually occurs in air. We have designed a Barcroft-manometer reactor to measure the rate of pyrite oxidation in air as a function of relative humidity and oxygen partial pressure. The reactor consists of two chambers joined by a manometer. Each experiment occurs at constant temperature, initial oxygen partial pressure, and relative humidity, although these variable can be changed between runs. Oxygen consumption was measured and pyrite oxidation rates were calculated from those data. Initial data indicate that rate of pyrite oxidation by oxygen in humid air is much faster than the rate of oxidation by oxygen in solution. The rates determined by this study can be used to develop better remediation techniques for acidic mine waters.

Jan 1, 2000