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By Richard R. Klimpel

In this paper, the old and the new commercially available reagent chemistries for the improved flotation of sulfide minerals will be summarized. The reagent classes discussed are those that meet three criteria: 1) they are being commercially used and/or large scale plant tested in North America in the last few years; 2) they are clearly different in chemical structure than commonly used commercial reagents of the last few decades and are not simply mixtures of existing reagents and/or simple changes in cation, alkyl group size, etc. and 3) the structural formulae are clearly specified in the public literature.

Jan 1, 1994

By P. Tsang, S. S. Peng

The stability of longwall chain pillars depends not only on the mechanical properties of the coal and surrounding rocks but also on geological and mining conditions. To evaluate the effects of each variable, orthogonal experimental design was employed in a significance analysis. The study concluded that the stability of longwall chain pillars is mainly controlled by the ratio of pillar stress to pillar strength, the ratio of the Young's moduli of roof to coal and floor to coal, entry width, pillar width and the internal friction angle of coal. Additionally, horizontal stress, panel width and mining height also play a significant role.

Jan 1, 1996

By Don L. Jensen

With the successful implementation of supervisory control on the Bagdad concentrator grinding circuits, steps have been taken to expand supervisory control to the flotation circuits. This paper discusses the design and installation of the slurry delivery systems, analyzing instruments, level control devices, reagent pumps and supervisory software. Emphasis is placed on the design and installation of a reliable slurry transport system to feed the Courier 30 online analyzing instruments. Total system availability has been measured at plus 95%. Phase 1 acceptance testing of the supervisory software indicates a notable increase in copper recovery with no significant change in final copper grade.

Jan 1, 1999

By A. Vargiu, R. Ciccu, G. Massacci

Based on the current results of field practice and on experimental data obtained in the laboratory with a suitable testing apparatus, the industrial operation of diamond wire cutting can be simulated by means of a mathematical model capable of predicting the cutting velocity and the wear rate of the tool, and thence the cost figures, achievable for a variety of conditions (kind of rock, size and shape of the cut, position of the equipment) according to a predetermined setting strategy (peripheral velocity, pull- back force). The paper gives a short outline of the model and discusses the simulation results obtained in a number of cases aiming at singling out the most favourable conditions for a cost-effective use of diamond wire.

Jan 1, 1996

By Daniel P. Coughlin, Robert C. Thomas, Christopher S. Romanek, Kristian W. Paul

Two separate constructed treatment wetland (CTW) systems receiving the same metal contaminated, acid sulfate water over different lengths of time and at different rates were evaluated for metal attenuation. Both wetlands are the alkalinity generator portion of a succesive alkalinity producing system (SAPS). Sequential extractions are employed to determine phases of metal removal. Results indicate that Fe, Al, Zn, Ni. and Cu accumulate in the organic substrate over time. Manganese accumulates initially, but is not retained in the system over time.

Jan 1, 2000

By Carolyn S. Watkins, Thomas E. Ward, Debby F. Bruhn, Vern Winston, Mary Lou Rowland, Deborah K. Bulmer

The genetic characteristics of members of the genus Acidiphilium are poorly understood. As part of our study of the genetics of these bacteria, a search was made for an endogenous bacteriophage. Such a bacteriophage has been discovered. Several properties of the phage have been investigated. The phage has a lambdoid morphology and is somewhat larger than lambda. A variety of factors which affect phage stability have been investigated. The bacteriophage infects several of the strains that have been tested. Study of this bacteriophage should greatly increase our understanding of genetic mechanisms in Acidiphilium.

Jan 1, 1989

By Y. M. Jiang, R. L. Sanford, D. W. Park

Artificial intelligence has emerged over the past two decades as an important problem-solving tool. Techniques include expert systems, neural networks, free classification, fuzzy logic and genetic algorithm. These methods can be employed to solve rock mechanics and ground-control problems associated with the highly complex nature of rock masses and ground conditions. A current study focuses on the development of an artificial-intelligence system for real-time interpretation of data collected from longwall monitoring stations and on the development of an early warning system for the prediction of undesired conditions and the prevention of longwall-mine instability problems. The successful application of these artificial-intelligence techniques will contribute to a safer and healthier mining environment.

Jan 1, 1997

By D. D. Harbuck, G. K. Green

The Bokan Mountain area on Prince of Wales Island, AK, contains vast quantities of heavy rare earth minerals. To lessen the US dependence on foreign sources, the US Bureau of Mines (USBM) investigated yttrium recovery from this ore. By sulfating the ore at 250 ° C for 1 hr at an H2S04:ore ratio of 1:1 and then water leaching the sulfated material for 1 hr at 20% solids and 25ºC, over 74% of the yttrium, cerium, and lanthanum were solubilized. Solvent extraction (SX), using a synergistic combination of OPAP and DEHPA, selectively loaded 100% of the yttrium. Yttrium was stripped directly as a solid using a 2M, 35 ° C NaOH liquor. When the OPAP/DEHPA mixture was tested in a continuous SX circuit, yttrium loading and stripping were 100% and 96%, respectively. The organic showed excellent recyclability properties with minimal solvent loss.

Jan 1, 1996

By Y. Luo, S. S. Peng

This paper presents some results obtained from research on long-term subsidence over and near chain pillar systems - the area available to long-term subsidence in longwall operations. Although the long-term subsidence for most longwall operations is insignificant, it does exist in some cases. In the cases that showed significant long-term subsidence, it was found that the development process could be expressed by an exponential decaying function. The stability factor of the chain pillar system and the potential for long-term subsidence are the two most important factors that control the magnitude and development characteristics of the long-term subsidence process.

Jan 1, 2000

By James G. Sampson

The discarded phosphatic clays from mining operations have historically been stored behind earthen dams for long periods of time before any reclamation was accomplished. In efforts to expedite the dewatering and reclamation of the clay ponds, the phosphate industry explored alternatives to conventional clay disposal practices. One alternative, employed by CF Industries, Inc., combines the clay and the discarded sand prior to disposal behind earthen dams. The sand encourages the clays to 'give up' trapped water more readily resulting in enhanced consolidation behavior. This paper provides an overview of the sand-clay mix process including the reclamation of sand-clay disposal areas.

Jan 1, 1992

By S. L. Bolivar

The Prairie Creek intrusion, near Murfreesboro, AR, is the site of the most famous diamond mine in North America. Three major rock types are associated with the intrusion-a hypabyssal peridotite, a volcanic breccia in which the majority of diamonds occur, and tuft. Previous studies, including geological, geophysical, petrological, and whole-rock and mineral chemistry are reviewed. The recent suggestion, by other workers, that this intrusion may be more correctly called a lamproite is examined. This has serious implications for diamond exploration in Arkansas and elsewhere in the US.

Jan 1, 1987

By S. B. Bhagwat

Equipment capacities of a sample of Illinois surface coal mines representing about 60% of surface production in the state were studied. Available equipment capacity was compared with the required capacity, as indicated by coal production and stripping ratios reported. Most mines sampled showed surplus equipment capacity, which if avoided, would result in substantial cost savings. The surplus capacity results mostly from market fluctuations that result in underutilization of equipment. Study findings underline the importance of market assessment at the time of mine planning and of communication between marketing and engineering arms of a coal firm.

Jan 1, 1987

By P. C. Rath, K. Srinivasa Rao, T. Subbaiah

A process for the recovery of nickel from ammoniacal leach liquor through an integrated solvent extraction-electrowinning (SX-EW) flowsheet was tested on a pilot-plant scale. The objectives of the test run were to assess the reproducibility of laboratory-scale data in a large-scale continuous operation and to study the build up of impurities in the system. The pilot-plant test was conducted under operating conditions that were established from the laboratory-scale experiments. Efficiencies of nickel extraction, nickel stripping and ammonia scrubbing were comparable to the laboratory-scale values, whereas the current efficiency during nickel electrolysis was observed to be less than the laboratory-scale values. The electrodeposited nickel contained some cobalt and iron impurities.

Jan 1, 1998

By H. Y. Sohn, H. K. Lin

The leaching of primary porphyry chalcopyrite ore under simulated solution-mining conditions was studied using a packed-bed reactor. A mathematical model incorporating the intrinsic leaching kinetics of chalcopyrite and pyrite grains, the pore diffusion of dissolved oxygen within the ore fragments, liquid-solid mass transfer, and the effect of fluid flow and axial dispersion was formulated and tested for the overall leaching process. The dependence of oxygen solubility on ionic strength of the solution was also incorporated into the model. Satisfactory agreement between model pre- dictions and experimental data was obtained. The model can also predict the rate of the leaching process under different temperatures, oxygen pressures, solution flow rates, and different size distributions of ores.

Jan 1, 1991

By N. S. Harding, M. C. Mai, A. G. Fonseca

Many coal characteristics affect combustion performance. Mill wear, boiler efficiency and derate, slagging, fouling, and ash collection and removal are only a few of the impacts of coal quality on boiler performance. The ability to assess fuel characteristic impacts on busbar costs is essential, although difficult to obtain. The relationships between coal characteristics and ignitability, operability, slagging, and fouling were investigated. The examination of combustion data/performance from a laboratory study, a boiler simulation system (pilot combustor), and commercial boilers indicated the benefits of burning improved quality coal. The specific effects of cleaning are discussed. A validation of the necessity of commercial-scale and/or pilot-scale testing is presented.

Jan 1, 1988

By N. Lydakis ? Simantiris

Preliminary results of a mineralogical, geo-chemical and nutrient analysis of soil samples collected from Omalos polje-plateau are presented. This study is part of a project concerning the relationship of lithology and mineralogy characteristics of soils of different geological origin from the island of Crete with their chemical composition, and more specifically with their ionic nutrients content. The results presented in this work show a relatively good correlation of the mineralogy and the bulk content of the soils examined with the available nutrients in soil solution.

Jan 1, 2005

By Leo J. Laughlin

In recent years, heavy mining applications have put an increasing demand on conveyor pulleys. This has resulted in the increased usage of turbine pulleys. The designs of these pulleys are often based upon the failures seen in the conventional welded designs, overlooking the interaction of pulley-shaft system components as the profile of the disc is modified. This paper will focus on the development of balanced design philosophy using case studies of turbine pulleys in heavy mining applications, evaluated with FEA.

Jan 1, 2002

By Hassan El-Shall, Abbas A. Zaman, Brij M. Moudgil

The addition of organic and inorganic dispersants to aqueous suspensions of heterogeneous particles (kaolin) was found to significantly affect the solubility of metal ions from kaolin particles and stability of the dispersion. In most of the industrial applications of kaolin, highly concentrated slurries of controlled stability and fluidity are required. The solubility of kaolin particles in terms of aluminum and silicon ions and its effect on the stability of the slurry was investigated. The main objectives of this study were (1) to study the effect of the extracted metals on the properties and performance of the slurry, (2) to understand the reaction mechanism of dissolution of metals from kaolin, and (3) to understand the interaction mechanism of dispersants with kaolin particles. The controlling variables were dispersant dosage, slurry pH, solids loading, and aging.

Jan 1, 2003

By B. K. Mishra, R. K. Rajamani

This paper focuses on the use of a numerical tool known as the discrete element method (DEM) to study the motion of ball charge in ball mills. DEM is employed to simulate the motion of individual balls. While doing so, the effect of liner design on the grinding performance of the mill is studied. Two important, factors, such as the configuration of the liner and the geometry of the lifting surfaces, are correlated with the overall mill performance. An attempt is made to show the effectiveness of the lifter bars in transmitting power from the mill shell to the interior of the mill, with particular emphasis on large diameter mills.

Jan 1, 1994

By J. V. Byrnark, R. W. von Bitter

The Hibbing Taconite Co. concentrator flowsheet, which is noted for its simplicity, uses single- stage autogenous grinding coupled with two stages of magnetic separation and two stages of size classification to produce a magnetite concentrate. This paper discusses the pilot-plant development of single-stage grinding, the commercial mill grinding performance, and mill liner development. Process innovation discussion includes process control computer implementation, size classification improvements, mill speed changes, magnetic separator improvements, and quality control innovations.

Jan 1, 1987