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By James A. Jones

The Doe Run Co. emerged from the depressed lead market of the mid-1980s as North America's leading lead producer. Doe Run was lean and mean but quickly recognized that technology had advanced while the company was held to the belt tightening slump. With the 1990s approaching, Doe Run moved quickly to update its technology and control equipment to ensure its position as an industry leader. Doe Run was formed in 1986 when Fluor Corp. and Homestake Mining Co. combined their lead-zinc-copper assets in Missouri to form a joint venture. Doe Run is now owned by Fluor Corp. A rich history of mining, milling and smelting started in Missouri in 1862 when the St. Joseph Lead Co. was founded. Subsequent acquisitions led to the formation of St. Joe Minerals, which was later purchased by Fluor Corp. Six mines, four concentrators and two smelters are presently being operated, and a secondary lead smelter was recently commissioned. The Viburnum, Buick and Fletcher operations are lead, zinc and copper flotation concentrators, while the Brushy Creek plant is set up to process high copper-low lead ores. This article looks primarily at the process control installation at the Fletcher concentrator.

Jan 1, 1991

By John C. Heter

The P.W. Gillibrand Company holds 705 placer and lode claims in the Precambrian San Gabriel Anorthosite Complex of the western San Gabriel Mountains. These claims contain large tonnages of ilmenite, magnetite and apatite with anomalous quantities of zirconium (zircon), niobium, vanadium and rare earth elements. Stockpiling of heavy mineral concentrates associated with aggregate mining from alluvial pits has occurred since 1984. The limited reserves of material from these alluvial deposits and their relatively low heavy mineral grades caused Gillibrand Company to initiate an extensive drilling and exploration program to develop the hardrock resources of ilmenite, apatite and magnetite.

Jan 1, 1995

By K. N. Han

The leaching behavior of palladium in ammoniacal solutions was investigated by using the rotating-disk technique in an autoclave. The study included the effects of rotation speed, temperature, oxygen pressure, composition of ammoniacal solutions and catalysts on the overall leaching rate. The dissolution of palladium in ammoniacal solutions was discussed in terms of the thermodynamics and a kinetic model. Even though the Eh-pH diagram suggests that palladium metal can dissolve in ammoniacal solutions at room temperature, it was found that the dissolution was very slow at temperatures below 100 °C but was significantly improved at higher temperatures. It was also found that the rotating speed of the palladium disk had no effect on the leaching rate. The apparent activation energy was found to he 69.7 kJ/mole. Based on the results obtained, it was concluded that the dissolution of palladium is controlled by chemical reaction.

Jan 1, 1999

By C. Bazin, D. Hodouin

Dynamic experiments were performed in a continuous open-circuit 40x40-cm ball mill using a pseudo-random binary sequence of the feed rate and measuring the variations of the discharge particle-size distribution. The impulse response is calculated by a cross-correlation technique. Then a model involving a discrete transferfunction and a time-series stochastic equation is calibrated using maximum likelihood methods. Based on this empirical model, a minimum variance controller with constrained input is designed and its performances are compared, by simulation, to the performances of a conventional PID regulator.

Jan 1, 1987

By Milton E. Wadsworth

Cost effectiveness in gold and silver leaching has centered mainly on reducing or preventing excessive use of lixiviants. In cyanide leaching practice, the active reactants, cyanide and oxygen, present different problems. The activity of cyanide may be adjusted at cost, but oxygen from air, has a fixed, low activity with an equilibrium concentration of ~7 ppm. Consequently, the use of air in agitation and heap leaching presents distinct kinetic problems. The refractory ores are either high consumers of oxygen or tend to immobilize dissolved precious metal-cyanide complexes. Commercial treatment of refractory ores involves oxidation by pressure leaching, roasting or biooxidation prior to cyanide leaching. Chemical reactions important in preoxidation of refractory sulfide ores by pressure leaching and biooxidation are considered. Major emphasis is given to the role of oxygen in heap leaching of oxidized ores.

Jan 1, 1995

By Edward F. Fries

Computerized, real -time monitoring had its beginning in the U.S. coal industry in the early 1970's. Over the last 10 years, developments in technology have made systems available that are capable of monitoring and controlling many mine parameters that can increase safety and production. However, situations currently exist where computerized monitoring systems are not being utilized to their fullest capability. They produce reams of printed output that are not sorted in a useful format, and human operators are not able to react fast enough in emergency situations tn tile large amount of information that the systems generate. A solution is the application of an expert system as the interface with real-time monitoring. An expert system would use an extensive knowledge base and human-type reasoning ability to make decisions on optimum strategies. Expert systems have been applied successfully to problems in other industries, and could provide significant benefits to mine information management systems. The use of an expert system with real-time mine monitoring is discussed in this paper.

Jan 1, 1986

By R. Velkova, D. Bojinova

The objective of the present investigations is to establish the effect of the preliminary mechanical activation of phosphates on the degree of phosphorus extraction by bioconversion of Bulgarian and Tunisian phosphates using A. niger fungi and T: thiooxidans microorganisms. The influence of the phosphate concentrations, the type of the nutritive medium and the incubation times on the process of biological mobilization of the phosphates was studied. When the concentration of phosphates in the medium is twice as high, an equal and/or higher degree of phosphorus extraction can be achieved through the bioconversion of mechanically activated phosphates compared with non- activated phosphates under similar conditions. A maximum degree of 90+% phosphorus extraction in utilizable form was achieved at definite conditions.

Jan 1, 2002

By Steve Garcia

GEORGE WEINMAN: Our next speaker is Steve Garcia, operations vice president and general manager of mining at IMC-Agrico, Florida. Steve was born in Lakeland, Florida, to an IMC mining family. He has 17 years with IMC-Agrico and Freeport companies, including assignments in North Carolina, Nevada, Arkansas, and Indonesia. His work within the industry includes technical and operating positions including chief metallurgist, drying superintendent, and mines operations manager at Pane Creek. Other experiences include design of a grassroots phosphate facility in North Carolina; construction and start-up of a gold facility near Elko, Nevada; work in the Blytheville, Arkansas, ammonia urea facility; and three years managing engineering, construction, and support services in Irian Jaya, Indonesia. Steve's presentation is "Evaluation and Standardization of Multiple Slurry Pumping Systems."

Jan 1, 1998

By D. W. Ashman

Today the electrolytic zinc industry is facing unprecedented environmental pressure and low metal prices. Zinc plants have to decide how they will dispose of iron residues in an environmentally friendly way without major capital expenditures. Only low-cost producers will survive, so companies must continuously improve to stay competitive. Therefore, the challenge of the process engineer is to find innovative solutions to the industry's problems. This paper reviews the status of electrolytic zinc processing and provides some insight into how the industry will respond to the pressures facing it

Jan 1, 1993

By Robert N. Evans, Delon Hampton

During construction of the Washington Metropolitan Area Transit System, the hand-mining of a mixed-face condition was anticipated on a portion of tunnel located in the downtown area of Washington, D.C. The Section, consisting of two circular tubes, extends from Station 12+80, heading in a westerly direction, traverses along a curve under Lafayette Square, and ends in a northwesterly direction at Station 37+62 (see Fig. 1a). It was near the northernmost portion of the section that the mixed-face condition was encountered. Decomposed rock was first encountered in the invert at Station 31+00. From this point the rock gradually increased in height until it intersected the springline at Station 37+62, the project limit. Summarized within this paper are measurements of the soil load on a horseshoe-shaped portion of tunnel located in the mixed face condition. These measured loads are compared to the soil load on tunnels as determined by current design methods. The paper also discusses rib and surface movements associated with the post loading process. Comments will be made on how the presence of a mixed face condition might help or hender the tunnel design and construction procedures.

Jan 1, 1974

By Alain Broussaud, Guy Fourniguet, Jacques Franck, Pierre Conil

Steady-state simulation is now in current use to assist mineral processing plant design and optimization. However, the reliability of results generated by simulators has not until now been seriously investigated. A simulator supervision algorithm was designed and programmed to study both the influence of the reliability of experimental data on the accuracy of unit operation model calibration, and the influence of unit operation model accuracy on the results of direct plant simulations. An application to a grinding flotation plant is described and discussed. The approach may open the way to the quantitative analysis of the risks taken in mineral processing projects, which would be similar to the application of geostatistics to mining projects.

Jan 1, 1990

By Fernando Concha, Arturo Barrientos

The flow in a hydrocyclone is divided into a boundary layer around the walls, an exterior inviscid flow and an air core in the center of the equipment. The boundary layer flow over the lateral walls is associated with the short circuit of particles to the underflow, while the boundary layer over the top of the hydrocyclone and the outer part of the vortex finder tube is related to the short circuit of particles to the overflow. Classification takes place in the exterior flow. The model can be validated with pilot or industrial data and simulates the performance of hydrocyclones in a wide range of design and operating variables.

Jan 1, 1992

By Richard E. Ray, George N. Aul, Fred Garcia, William P. Diamond

Increasing longwall panel dimensions, particularly face width in gassy coalbeds, may result in unexpected increases in methane emissions. To investigate this problem, continuous longwall face emission monitoring studies were conducted at two adjacent mines operating in the Pocahontas No. 3 Coalbed, where longwall faces were to be extended from 229 to 305 m (750 to 1,000 ft). It was predicted by regression analysis of methane emissions data from 229 m (750 ft) wide longwall faces that extending faces to 305 m (1,000 ft) would increase methane emission rates by only 7 percent (0.6 m3/min (20 cfm)), to 8.6 m3/min (304 cfm) at the VP-1 Mine. In contrast, it was predicted that extending faces at the VP-3 Mine could increase methane emissions by as much as 13 percent (1.8 m3/min (65 cfm)) to 16.1 m3/min (567 cfm). The geologic and mine design factors in¬fluencing the variation in face emissions between the two mines will be discussed.

Jan 1, 1997

By John Marsden

JIM ARNOLD: Our next speaker is John Marsden. John runs the concentrator complex at La Candelaria Project in Chile. John's a Royal School of Mines graduate and he wrote the book on gold metallurgy, The Chemistry of Gold Extraction, which, by the way, he dedicated to me-at least that's what my copy says. [laughter] John, go ahead. (Message shown on Projection screen) ‘Raulerson’s Rules Plant operators and maintenance personnel should be asked to participate early in the design process. This ensures that the plant will never be completed on time or within budget.’ JOHN MARSDEN: Good afternoon, everybody. My presentation this afternoon is going to be very short. It won't be as funny as Joe Keane's, but I guarantee you it will be a lot quicker. [laughter] That transparency isn't mine, actually. [laughter] You're trying to throw me off.

Jan 1, 1998

By J. J. Scott, G. H. Bennett

INTRODUCTION Friction Rock Stabilizers, commonly called Split Sets,tm* have been under development since early 1973. Five years of intensive laboratory and field testing led to their introduction to the metal mines in the United States in the fall of 1976. Actual sales started in February of 1977 and, to date, over five million units have been marketed to metal mines. The present rate of useage is near 3 1/2 million units per year which is approximately 50 per cent of all roof fixtures used in the United States metal mining industry. Mr. Richard Hoppe, Senior Editor of Engineering & Mining Journal, in an article of the February, 1979, issue, entitled "Winning the Battle Against Bad Ground", said, "In hardrock mining operations in the western U.S., particularly underground uranium mines where exceedingly difficult ground is common, no roof support system has been accepted more quickly than the Split Set friction bolt invented by Dr. James J. Scott and developed by Ingersoll-Rand Co." This paper describes how Friction Rock Stabilizers function and presents technical data to show the uniqueness of the Friction Stabilizer system. SPLIT SET STABILIZERS The Split Set System is a revolutionary development in the field of ground control. The system produces an interior reinforcement to a rock mass which: *Trade Mark of Ingersoll-Rand Co.

Jan 1, 1979

By J. S. Walker

Public Law 95-87 enacted by Congress in 1977 and subsequent regulations require coal mine operators to predict the effects of mining on the environment prior to the start of mining. Prediction of the effects of mining on the local groundwater system is a difficult task due to its complex nature and the lack of detailed published information. An investigation of water level fluctuations in five we1 1s positioned over three consecutively mined longwall panels was initiated in conjunction with an intensive subsidence monitoring program. The purpose of this work was to provide detailed information which could be used to predict certain hydrologic effects of longwall mining in the Northern Appalachian Coal Region. The results of this case study indicate that water level fluct- uations in the local ground-water system above longwall panels is associated with subsidence and that the static water level will generally re- establish at or near the pre-mining elevation after mining is completed.

Jan 1, 1986

By Kenneth N. Han, Jianshe Liu

Various techniques used in the removal of metal ions from effluent streams have been reviewed. These techniques include recovery of metals by biological treatment, chelating agents, adsorption, ion- exchange and chemical precipitation. The main thrust of this paper however, is concerned with the removal of cadmium and zinc ions from the solution by adsorption utilizing liquid fluidized beds. The bed particles used were silica of 150x200 mesh. The range of the concentration of these ions studied was 10-3 to 10-5 M. Important variables examined included flow rate, concentration of metal ions and amount of bed particles. A mathematical model describing the concentration profile of metal ions in the axial direction in liquid fluidized beds has been developed. The equation of continuity was solved numerically and the results were used to predict the recovery of metal ions in fluidized beds.

Jan 1, 1992

By Y. Q. Zhang, Y. Luo, S. S. Peng

Burrier pillars in underground coal mines could eventually be subjected to a water head due to the build-up of mine water in the old workings. The water head could not only act ns a force to destabilize the pillar, but it could also cause seepage flow through the pillar and its surrounding strata. Excessive seepage flow could induce piping failure that, ill turn, could accelerate the mechanical failure process of the barrier pillars. In this paper, a finite element simulation approach was employed in the evaluation of the barrier pillars. Both the stress distribution and the seepage flow pattern in and around a barrier pillar have been simulated numerically. The effects of ground stress on rock permeability to water seepage has been taken into consideration in these simulations,

Jan 1, 2002

By S. G. Malghan

This paper reviews uses of sodium sulfide in the flotation of oxide minerals of copper, lead, and zinc. The activation and depression effects of sodium sulfide are of particular importance because of their applications with oxidized lead and copper ores. In spite of its industrial importance, the nature of the heterogeneous reactions between sulfide ions in solution and the surface of oxidized minerals has not been fully understood. Hence, proposed mechanisms of the sulfide action in flotation, methods of measuring and monitoring sodium sulfide in flotation pulps, and variables influencing the sulfide addition are analyzed. Recent studies on sodium sulfide addition to flotation pulps, monitoring its concentration, and the optimum dosage control using platinum and/or sulfide specific ion electrodes are discussed.

Jan 1, 1987

By Frank L. Bazzanella

Se presenta una breve introducción de la concentración gravimétrica, incluyendo alguna discusión sobre los minerales mas comunes recuperados normalmente. Se mencionan las consideraciones importantes para el diseño básico de una planta de concentración y se presentan cuatro esquemas de flujo sobre las operaciones más corrientes. Las plantas estudiadas en detalle incluyen: "Climax Molybdenum Co. By-Product Plant" y "Canada Tungsten Ltd. Plant". Las plantas brevernente reseñadas incluyen: "Palabora Mining Co. Uranium Recovery Facility" y "Bridge Hill Ridge Heavy Mineral Recovery Plant of Mineral Deposits Ltd."

Jan 1, 1982