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By R. L. Wiegel

There are approximately 40 million tons per year of phosphate rock produced in the United States, half of it by flotation. The bulk of this is used to produce diammonium phosphate, an essential ingredient in the commercial fertilizer mixes used by the thriving U.S. agricultural community. This paper describes the mineral beneficiation practices of the phosphate industry, with special emphasis on flotation. There is also an attempt to include those items that might be considered emerging technologies for the industry as it faces the problems of a diminishing high-grade reserve and the necessity for implementing dolomite/francolite separations.

Jan 1, 1999

By Frank Matter

Production of ultrafine powders of industrial minerals has been a problem in the past. In recent years new wet and dry grinding stirred ball mill systems have emerged which have been commercialized Two such systems are the TRZK mill with double step air classifier for dry grinding and the NRZK mill for wet grinding The primary features of these mills are feed entering from top and the product along with the grinding media leaving from the bottom, and a media separation and recycle system A detailed description of the NRZK mill for grinding coal is presented

Jan 1, 1983

By Dan Kump

This paper provides an overview of Barrick Gold's Bullfrog underground mine backfill program. The Bullfrog underground mine was a gold mine that primarily used the underhand cut-and-fill mining method. The first portal was established June 18, 1991, and mining continued until Dec. 29, 1998. This paper begins with a discussion of the events that took place to reach about 1.8 kt/d (2,000 stpd) of backfill. It ends with a commentary of what was learned. The Bullfrog experience suggests that there are two essential factors to a successful backfill program: a well-graded aggregate supply and proper placing procedures.

Jan 1, 2002

By Roy Eric Lurie

Computer based signal processing techniques for obtaining empirical dynamic models from measured mill circuit data are discussed. This modelling is the first step towards designing a particle size control strategy. Experimental data from a computerized acquisition sys tern is examined and analysed, and a number of model identification procedures are applied. The resulting models are compared and a suitable model is selected, illustrating the benefits of computer tools for control system design.

Jan 1, 1992

By Zhang You-di

A comprehensive model has been set up for surface mine long range planning. It is a system simulation model based on the oriented graph theory. Via this model, a series of mining results such as mineral and waste volume, mineral quality, mining intensity, material haulage distances, dumping area parameters and mining coat for different mining alternatives, can be derived and optimized. This model has been applied to 37 mining alternatives in several surface coal mines and proved mathematically correct and results reliable.

Jan 1, 1986

By Jerry L. Hodgson

This paper presents an application case history of the planning methods used for developing, costing and scheduling an underground hydro- electric pumped storage facility in weak rock. This method covers the system configuration, excavation methods and costs, initial support systems and final lining systems. This study was performed by the Omaha District, Corps of Engineers for the proposed Gregory County Hydro- electric Pumped Storage Project, and presents a synopsis and the results of the studies performed.

Jan 1, 1986

By P. M. Lin, P. Tsang, S. S. Peng

This paper presents an overall stabilization method to eliminate the potential of reoccurrence of subsidence over abandoned mine lands (AML). The method considers column grouting at specific locations, including the destressed and stress concentration zones, instead of grouting around and beneath damaged structures. The latter method is currently commonly used for AML subsidence abatement. The finite element method (FEM) can be used to calculate stress distribution in the strata before and after grouting. A grouting pattern is generated that includes the location and number of grouting holes. Stress concentration can be reduced or eliminated. A comparative analysis, including the number of grouting holes, area of grouting influence, stress level and potential of subsidence reoccurrence, is also presented.

Jan 1, 1993

By Dennis L. Boley, Francesco Gallavresi, Donald A. Bruce

The authors describe novel aspects of ground reinforcement and treatment as related to soft ground excavation for tunnels throughout the world. Insitu reinforcement for cut slopes (soil nailing), as underpinning (reticulated micropiles), and as direct tunnel support (infilaggi) is introduced. Ground treatment focuses on new aspects of permeation grouting (by the tube'a manchette system), and on jet grouting-a very powerful and positive new technique. Recent developments in equipment, materials, methods and instrumentation are reviewed, with special reference to major tunnelling projects in Italy and Singapore.

Jan 1, 1987

By Eric Monrad

Discrete event simulation modeling provides a tool to quantify the throughput capacity of stockyards. Interactions between the main equipment types (trains, dumpers, conveyors, stackers, reclaimers, shiploaders) can be captured, including route blockages, breakdowns, and planned maintenance. Simulation has been successfully used at world-class stockyard facilities to determine current capacity and to identify gains resulting from improvement projects. Recent projects have focused on iron-ore, coal, and soya facilities, but the technology is suitable to be used on any bulk material type.

Jan 1, 2008

By Frederick P. Schwarz

Sample preparation and analysis can impose devastating errors on assay data. Minimizing these errors by testing and procedural redesign may be critical to assure representative assays and project success. Replicate samples, taken at any volume-reduction and/or analytical step in a sampling procedure, generate replicate assay values whose relative differences constitute a set of data. Variance of this data judges the addition to total sampling error imposed by the step generating the replicates. A variance more than (11.5%)' is excessive for a single step. Sample volume increase and/or comminution at a step will reduce variance for that step. Rejects from well mineralized intercepts can provide bulk samples for testing.

Jan 1, 1989

By J. S. Lewis

Beneficiation and physical and chemical processing of non-terrestrial materials will borrow strongly from terrestrial experience but will also involve the necessity of handling literally unEarthly feedstocks, reagents and environmental conditions. The present state of scientific and engineering understanding of the processing of non-terrestrial minerals, gases and hydrocarbons is reviewed, with the production of rocket propellants, life-support fluids, structural metals and refractories as the goal.

Jan 1, 1994

By Shaoxian Song, Shouci Lu, Jingyon Gou, Pan Yiuwen

The calculated potential energies of interaction between hydrophobic particle of three minerals (rhodochrosite, quartz and talc) and air bubble show that the energy of hydrophobic interaction is the dominant factor for their attachment. An attachment rate equation, integrating particle -bubble collision and adhesion by introducing a "capture efficiency", has been put forward. It was found that the hydrophobic particle-bubble aggregates can not be disconnected in the bulk zone of flotation cell, whereas in the impeller zone the breakup may occur, particularly for the coarser particles captured by bubble. Finally, the flotation rate constant was estimated theoretically and verified by experiments.

Jan 1, 1995

By J. C. Barker

Alaska, with about 74% of the US continental shelf, is largely unexplored for placers in its vast shallow marine waters. Nevertheless, there are numerous occurrences of marine minerals including gold, platinum, and cassiterite. Offshore dredging has recently begun in the Nome area. State and Federal agencies are preparing additional acreage for leasing. With 76,200 km (47,300 miles) or 54% of the US coastline, Alaska is a vast, largely unexplored frontier for shallow-water marine placers. Despite the general lack of mapping and only sporadic past prospecting, many prospects are known and a major mining operation for gold has recently begun offshore of Nome. Due largely to the demonstrated success of the Nome operation, the US Minerals Management Service is preparing to conduct a lease sale of additional acreage further offshore from Nome. And future sales are being considered elsewhere by both the Federal and state leasing agencies.

Jan 1, 1990

By R. W. Smith, R. K. Mehta, X. P. Zheng, A. M. Raichur, M. Misra

Experimentation was per formed on the flotation of apatite and dolomite separately using anionic collectors in the presence of Mycobacterium phlei. Also, the flotation of mixtures of dolomite and apatite in the presence of anionic collectors and in the absence and presence of the bacterium were studied. It was found that M.phlei functions as a depressant for both minerals. However, it functions as a better depressant for dolomite than for apatite. Experimentation was extended to two different Florida dolomitic phosphate rocks. In this investigation a concentrate grade of less than 1.0% MgO was achieved with a 75% P2O5 recovery.

Jan 1, 1999

By G. X. Wang, J. O. Marsden, M. C. Fuerstenau

Zinc cementation of high-temperature carbon eluates is now used extensively in gold processing to replace electrowinning. Under these conditions, zinc consumption is high. In this paper, zinc solubility is press rated us functions of temperature, cyanide concentration and pH in the presence of gold, silver and mercury cyanides (both individually and in combined solutions). Based on the experimental results, cementation of these metals is characterized and discussed. The importance of cyanide concentration in cementation efficiency and the effect of mercury and its co-precipitation onto zinc are also discussed.

Jan 1, 1997

By G. Banini

A plug-flow model is described for the reactor mass balance of a typical AARL gold elution process. The model is in the form of a hyperbolic differential equation and was transformed using the method of characteristics. The transformed model was then solved simultaneously with models dependent on intraparticle surface diffusion and film transfer parameters. The solution was found to represent the experimental data for a modified form of the AARL elution. Correlation between the experimental conditions and the film transfer parameters estimated by the model are also presented.

Jan 1, 1998

By A. S. Polubinsky, V. P. Chernyak

A further development of the theory of heat- and mass transfer in the system “strata - mine opening" is necessary for an improvement of the existing technique of heat calculation of mines and other underground constructions. A generalized boundary problem of heat- and mass conduction in strata around an opening as a theoretical ground for that purpose and several particular situations, important from the point of view of an opening and surrounding strata heat state analysis, as well as results of numerical experiments executed for such analysis are presented.

Jan 1, 1997

By Guoming Liu, Weibai Hu

The designing aspects of column profile, cross-section and height, types of aerator or air sparger, and feeding and discharging devices have been designed and tested. In operating aspects, the flotation column: has beer, compared with the conventional mechanical flotation machine in large- scale plant practice. It has been found that the reagent conditioning time and the slurry residence time required in the column are longer than those in the mechanical flotation machine. The general opinion is that the flotation column can show some effectiveness in specific cases as long as it is properly designed and carefully controlled.

Jan 1, 1988

By Regina N. Tempel, Laurie S. Balistrieri, Lisa L. Stillings, Maggy F. Lengke

The Dexter pit lake, within the Tuscarora volcanic field in Elko County, Nevada, formed after closure of the Dexter mine. Mineralogy at the Dexter mine is related to widespread feldspar, silica, and chlorite alteration. Major mineralogy includes quartz, alkali feldspar, albite, phlogopite-biotite, hornblende, iron-titanium oxide, chlorite, kaolinite, smectite, illite, and sericite, with lesser amounts of calcite, zircon, apatite, and rutile. Trace element geochemistry is characterized by high levels of As, Ba. Cr, Cu, V, Zn, B, Zr, Li, and U. Detailed mineralogy and geochemistry are required for geochemical models to accurately predict trace element concentrations in pit lake waters.

Jan 1, 2000

By D. G. Fredlund, J. A. Wilson

Conventional disposal of waste rock results in the construction of benches with fine and coarse layers dipping at the angle of repose. This interbedded structure influences flow pathways within the waste rock. A numerical modeling program was conducted to study a four-layer system consisting of alternating fine and coarse waste rock. The system was inclined from the vertical to forty-five degrees with heights varying from one to twenty meters. The results show the effects of gravity as preferential flow developed under unsaturated flow conditions.

Jan 1, 2000