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By George W. Poling

Designing optimal placer gold recovery plants requires a detailed knowledge of the size, shape and surface physical characteristics of the gold particles and the host alluvium in the pay gravel, sand or clay. Results of a recent pilot-scale study of the quantitative performance characteristics of riffled matted sluice systems are presented. For the appropriate non-coherent pay gravel-sand with medium-flat gold, simple sluices can recover gold at greater than 85% efficiency down to 100pm diameter. Alternatives to simple sluices are presented and discussed briefly.

Jan 1, 1987

By Dean D. Turner

Exploration geochemistry requires computer processing for quick and efficient reduction and interpretation. An easy to use microcomputer based geologic workstation fulfills this need and allows the geologist to independently process geochemical data. Functions necessary for geochemical data processing are: 1)Digitizing; 2)Communications; 3)Data base management; 4)Statistical analysis; 5)Mapping analysis; and 6)General purpose applications (ie: word processing). A geologic workstation that can perform these tasks will yield significant advantages in processing and interpreting geochemical data.

Jan 1, 1987

By R. D. Miller, D. W. Steeples

Seismic reflection is a powerful geophysical exploration method that has been in widespread use in the petroleum industry for more than 60 years. This paper addresses some basic principles of the method and its application at depths shallower than 30 m (100 ft). Since 1980, the shallow reflection technique has been increasingly used for engineering and environmental problems, such as mapping bedrock beneath alluvium and delineating intra-alluvial features near hazardous waste sites, detecting voids in coal and karst, defining the top of the saturated zone and mapping shallow faults. New applications will be added with improved resolution and increased cost-effectiveness.

Jan 1, 1994

By T. S. Mackey

The industrial types, sources, and quantities of US tin residues are identified and the methods of treatment reviewed. The effect of a lower tin price, due to a current major world surplus of tin metal, is mentioned and covered in some detail. The names and locations of over 100 US firms recovering tin residues are listed. Current smelting and refining charges are included to convert the residues into tin metal and alloy. The impact of the complete with-drawal of the LME daily tin price since Oct. 24, 1985, and the collapse of the International Tin Council, which at one time supported the Buffer Stock Manager, are reported with comments.

Jan 1, 1987

By C. W. Schultz

Introduction The Mineral Resources Institute, The University of Alabama, has for the past three years been engaged in a program to develop a beneficiation system for eastern (Devonian) oil shales. One objective of that program was to evaluate advanced technologies for effecting a kerogen-mineral matter separation. Column flotation was among the advanced technologies selected for evaluation. Early in the program it was shown that column flotation was superior to conventional (mechanical) flotation and to the other advanced technologies being evaluated. The investigation then proceeded toward the further objective of defining the optimum operating conditions for column flotation. One observation made in the course of optimization testing was that introducing the feed into the froth (above the pulp-froth interface) resulted in an improved combination of concentrate grade and kerogen recovery. This observation was reported in a previous paper (Schultz and Bates, 1989). Because the practice of maintaining the pulp froth interface below the feed point is contrary to "conventional" practice, it was decided to subject the observation to a systematic series of tests. This paper describes a recent series of tests and the results that were obtained.

Jan 1, 1991

By S. Zhou

Since the hypothesis of coal and methane outburst mechanism based on elastic mechanics gives no consideration to time, it can not give a satisfactory explanation to the outburst occurrence and its development. A creep mathematical model of coal containing gas has been set up through creep tests and analysis under the condition of tri-axial compression. And the model can explain the phenomena of coal and methane outburst successfully. The tests proved that there is no essential difference between the rheological properties of prone outburst coal and non-prone outburst coal. Outburst can take place in any kind of coal if the rheological conditions of coal containing gas are met. The creep mathematical model provides a basis for establishing a comprehensive index of coal and methane outburst possibility.

Jan 1, 1991

By S. Chunhui, W. Anbin, R. B. Cook

The Xicheng is one of China's largest lead-zinc (Pb-Zn) districts with known minable reserves in excess of 10 Mt (11 million st). The centrally located Changba-Lijiagou and nearby deposits are representative of the district. They consist of stratiform and stratabound zones of pyrite-sphalerite-galena mineralization within deformed, moderately metamorphosed Middle Devonian clastic and carbonate units. When considered with other similar districts that extend for several hundred kilometers to the east, a major episode of Devonian sedimentary exhalative mineralization is indicated.

Jan 1, 1992

By A. M. Johnson, D. H. Carlson, D. L. Johnson, S. T. Bagley

A biologically assisted ferric iron leaching system was evaluated for in situ recovery of three copper sulfide oresfrorm northern Michigan. Laboratory scale bacterially assisted ferric sulfate leaching tests were run on the three ores. A T. ferrooxidans strain was found that could be adapted to copper in solutions at concentrations as high as 20 g/L. Column leaching of 4.5 to 2 mm (-4 +I0 mesh) material yielded extractions of 80-90% copper from one ore and 70 and 60% from the other ores. The highest copper extractions were from the Mount Bohemia ore deposits located in the Keweenaw Peninsula, which have fracture controlled chalcocite mineralization. The Bohemia ores are apparently well-suited for in situ solution mining.

Jan 1, 1987

By Y. Nakahiro, T. Wakamatsu, M. S. Elsalmawy

The flotation of quartz, feldspar and alumina was studied as a function of pH when using N-alkyldiamines as collectors. The lengths of alkyl chains of diamines were 8, 9, 10, and 12 carbon atoms. It was found that shorter hydrocarbon chain length of alkyldiamines has stronger tendency to float quartz while the feldspar responded poorly to flotation with these collectors at high pH values. The effect of addition of nonionic surfactant of Brij type, when using dodecadiamine as collector, was investigated. Flotation studies in the absence and in the presence of sodium dodecylsulfonate were carried out. These studies have indicated that sodium dodecylsulfonate, in the concentration studied, functions as strong depressant for feldspar.

Jan 1, 1995

By G. Pierson

Explanations for commodity price levels (or movements) commonly focus on the fundamentals of supply and demand, otherwise they are simply assigned to speculative activity. Comparisons of metal-price histories to monetary and other economic data support the argument that the supply of and demand for money are no less important in the determination of price than are the supply and demand of the commodity itself. That these relationships should exist is evident in the price identity and they are consistent with monetary theory. The patterns developed have limited usefulness as predictors, but their recognition is essential for the construction of price scenarios for planning purposes.

Jan 1, 1997

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

An on-line monitoring system for apparent slurry viscosity has been developed at Michigan Technological University. It utilizes a vibrating sphere viscometer in conjunction with a special slurry presentation system to reduce particle settling and turbulence effects. It has proven to give accurate, reproducible results in an on-line hydrocyclone installation. Its performance shows that it can be an effective instrument on an industrial scale, particularly in grinding circuits. Development of the sensor and the importance of rheology in grinding are also discussed.

Jan 1, 1992

By Robert P. Edwards, Brian C. Flintoff

Crushing plants (multiple stage) are an integral part of most conventional comminution circuits (ball mill, rod mill - ball mill). Although conventional circuitry is now the design exception, there are still many older, and some newer plants that include crushing in the process flowsheet. In most of these installations the operating objective is to maximize throughput at some minimum product size, in an effort to balance the comminution load between crushing and grinding. To achieve this goal, while avoiding production losses due to overloads, generally requires the use of automatic control strategies. This paper reviews the crushing plant control problem and describes several approaches that have been successfully implemented in different plants.

Jan 1, 1992

By A. K. Haines, M. W. Godfrey, D. M. Miller, P. C. van Aswegen

The Bacterial Oxidation [(BIOX)] process for the pre-treatment of refractory ores for gold recovery developed by Genmin, the mining division of Gencor, has been operating successfully at the Fairvew Mine since October 1986. The continuous operation of a pilot plant at Genmin Process Research has resulted in further process developmenst to improve plant operating efficiencies. These new developments, which include a higher solids content of the pulp feed to [BIOX], lower retention times, higher operating temperatures, lower power utilizaton for oxygen dispersion and reduced nutrient addition, have all been successfully implemented on the Fairvew plant. It has furthermore been confirmed that the arsenic precipitate formed in the neutralization of effluent solutions complies to the United States of America EPA standards. Contineous cyanidation pilot plant work conducted on [BIOX] product has indicated that cyanide consumption can be drastically decreased if a continuons flowsheet is implemented in preference to a batch leaching system.

Jan 1, 1992

By Justus B. Deen

Given that the majority of mine ventilation operating costs are imposed by shafts, the need to predict the resistance of a planned shaft with reasonable accuracy is important. During conceptual design, shaft resistances are usually predicted by use of published friction factors, k, based upon lining and fitting configurations. More often than not, published friction factors do not directly coincide with "real" shafts, so their use is somewhat limited. For more accurate shaft resistance determination, equations both theoretical and empirical may be employed if there is detailed knowledge of the shaft. These equations treat the shaft resistance as discrete components, with their sum being the overall shaft resistance. This paper describes the basic shaft resistance equations and verifies these equations by comparison to field measured shaft resistances. Several shafts were examined which varied in depth, shape and fitting arrangements. Results are presented and conclusions drawn to show that the shaft resistance equations are accurate.

Jan 1, 1991

By Michael J. Rinker, R. V. Nicholson

Waste rock and tailings from a proposed nickel-copper mine were evaluated extensively for potential on-land and under water disposal. Standard humidity cell and column tests were conducted over a two year period and underwater tests were conducted for more than one year. Nickel concentrations or release rates from the waste were consistent with nickel to sulphur ratios in the solids. This relationship provided a tool to assess the risk of metal leaching in wastes using nickel and sulphide assays. Nickel release and mobilization was found to occur for both oxidizing leach tests and under water tests even when pH values exceeded 7.0. Geochemical model calculations showed that iron oxyhydroxide solids can scavenge nickel from leachate and that the nickel inventory can be released from solids at relatively lower, but neutral pH values.

Jan 1, 2000

By Bruce B. Redpath

Single-charge cratering tests can provide a direct measure of the powder factor necessary for achieving a desired effect in conventional blasting. If a desired blast effect, such as fragmentation or mound velocity, is produced by a single point-charge at a particular scaled depth of burial, then the cube of the reciprocal of that scaled depth is the appropriate powder factor for duplicating the effect in a conventional array of blast holes. Scaling formulas are presented that provide a link between point-, line- and plane-charge geometries, and which can be Apparent crater used for blast design. Mound and burden velocities from several sources are compared and several examples of blast design are given.

Jan 1, 1977

By J. Mark Richardson

Modern mining operations are increasingly affected by complex economic factors. Broad and rapid fluctuations in metal prices, rising operating costs, socio-political trends and the inherent technical difficulties encountered in most operations, all can combine to quickly change once-profitable ventures into money-losing propositions. Accurate knowledge of metal inventories during all phases of an operation has become essential to wise management decision-making. This paper reviews key elements of metallurgical accounting: sampling theory, measurement technology and computerized data adjustment. Application of current technology to the reconciliation of a hypothetical operation is discussed.

Jan 1, 1991

By John F. Schat, T. William Thompson

Laboratory data on the time-dependent compaction of porous rocks are presented, and various attempts to model this behavior are described. These lead to a discussion of the problems that arise in using laboratory data to estimate long-term effects. A method is suggested for combining laboratory data with information from the geologic record to estimate long term effects.

Jan 1, 1986

By David M. Spatz

Team, as defined by Katzenbach and Smith (1993), is a small number of people with complementary skills who are committed to a common purpose, performance goals and approach for which they hold themselves mutually accountable. As the mining industry searches for new ore discoveries increasingly under post-mineral cover, the process of mineral exploration has taken us from prospector to geologist to multidisciplined explorer to multi-disciplinary team. Multidisciplinary exploration techniques have improved in terms of sensitivities and penetration and more than ever before each technique requires specialists with appropriate training and skills to process data and interpret results. To produce a quality product, specialists must collaborate openly and honestly in an atmosphere where the collective result takes into account the knowledge and expertise of each individual and the relationships between all pertinent data sets.

Jan 1, 1998

By Lynn B. Hales, Randy A. Ynchausti

Object-oriented technologies have been developed to more closely model the way we think about the world and our natural approach to solving problems. Higher levels of abstraction, generalization and classification are benefits of an object-oriented approach. Object-oriented programming, design, and expert systems are part of this technology which is shaping the future of real-time supervisory control. Goals of real-time supervisory control systems include: minimizing variations in process operations, improving efficiency, maximizing production, and implementing procedures for starting and stopping the process. Incorporating object-oriented technology in design, development and implementation of real-time supervisory control systems provides new opportunities for these tasks. This paper discusses some of the opportunities and challenges of implementing real- time supervisory control using an object-oriented expert system for a rougher flotation circuit

Jan 1, 1993