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By D. Ince

Flotation of dolomite from apatite was investigated, using dodecylamine hydrochloride or sodium oleate as the collector, with and without inorganic modifiers such as sodium chloride. Separation of dolomite from apatite was anticipated from the single mineral experiments under various pH and collector concentration conditions. Flotation selectivity in the mixtures, however, was found to be limited. Attempts to control the flotation response of these minerals by addition of salts such as NaCl and KCI indicated that selectivity is possible. The presence of sodium chloride was determined to depress apatite flotation using sodium oleate, leaving dolomite flotation unaffected (Moudgil and Ince, 1989). In this paper, conditions for optimum separation and the effect of major parameters on the desired selectivity are discussed.

Jan 1, 1992

By D. R. Spears, C. E. Jordan

The U.S. Bureau of Mines examined the influence of turbulence on the fine bubble flotation of fine-sized (minus 40 micron) galena in order to improve flotation efficiency. Fine bubble flotation was carried out in a spinning-disk flotation cell and was compared to results obtained from flotation in a conventional cell at equivalent agitation levels. An automated electrochemical technique was used to monitor the turbulent velocity distributions of the fluid within the cell as a function of time and position. The velocity profiles were used to increase the precision of the fine particle, turbulent flotation model. While improved flotation response was obtained with intense agitation, the effect of bubble size was small. These results matched the model's predicted response for fine particle flotation.

Jan 1, 1989

By Walter C. Labys

There has been considerable growth in public enterprise institutions involved in mineral commodity markets. These institutions typically consist of trading organizations (STO1s), regulatory agencies, and mixed agencies. The particular character of these institutions varies according to whether they reside in developing countries, in Eastern Europe (COMECON Countries), in industrialized countries, or in the form of international agencies. The purpose of this paper is to explain recent attempts to assess the growth of public enterprises as well as their impacts on mineral markets and trade. Some earlier analyses of market impact made by the author have been up- dated for four major mineral markets: copper, tin, bauxite and iron ore. Conclusions are drawn regarding the dynamics of market structure changes and their impacts.

Jan 1, 1986

By Robert Stauffer, John Frostiak, Rein Raudsepp

Placer Dome's Campbell Red Lake Mine in Balmertown, Ontario produces a refractory gold flotation concentrate containing the sulphide minerals arsenopyrite, pyrite and pyrrhotite. In 1991, the existing concentrate roasters will be replaced with a pressure oxidation plant based on Sherritt Gordon technology to update the facilities and to satisfy environmental requirements. A successful continuous pressure oxidation miniplant program was conducted by Sherrill Gordon in late 1989 which formed the basis for the design of the commercial plant. The paper summarizes the Campbell operation and the environmental aspects of the project, and discusses the results of the miniplant program and the design of the commercial plant. The capital cost of the pressure oxidation plant and the process operating costs are also presented.

Jan 1, 1990

By A. B. Phillips

The Randfontein Estates Gold Mining Company (Witwatersrand) Limited (REGM) operates three metallurgical complexes for the recovery of gold from the Witwatersrand Gold Reefs at the town of Randfontein, 40 kilometers west of Johannesburg. Mining operations in the. area commenced in March 1889 and ceased temporarily in 1965 when the viable ore reserves had been depleted. Exploratory drilling in the 1960's indicated viable deposits of gold in the Elsburg reefs, south of the Witpoortjie Horst Block, _which formed the Southern limit of the previously exploited areas. Three shaft complexes have been established to exploit this area, known as the Cooke secti'on. In 1983 the Doornkop shaft was sunk to the north of the Cooke section to mine Kimberley reef and the South reef.

Jan 1, 1992

By Jim V. Rouse

The decision to hold parallel conferences dealing with hazardous waste and mining waste grew out of the conviction that there were advantages to having personnel serving the two groups talk to each other, as both groups develop cost-effective and environmentally-protective solutions to present and future waste-disposal problems. There has been a certain amount of "reinventing the wheel" which could have been avoided by a better dialog between the two groups. The intent of holding the two parallel conferences is to allow for networking, to minimize future needless redundant effort. The opening session panel speakers represent expertise from both industries; I feel honored to speak as one with a history of serving both groups as a specialist in the subsurface behavior of heavy metals.

Jan 1, 1991

By G. Gaidajis

In this paper, a semi-qualitative methodology is presented and then applied to an aluminium extrusion industrial facility in order to perform an initial environmental assessment. The results of the assessment enable an improved understanding of the environmental performance of the facility and more importantly identify the areas of significant environmental concern. Following, the application of case-specific sustainability indicators related with the areas of significant environmental concern, leads to a more comprehensive sustainability assessment. The applied two-step approach offers a quick and reliable environmental assessment and help focusing on the most environmentally problematic areas. Moreover, the follow-up of the specific indicators seems to be appropriate for the improvement of the environmental performance of the examined industrial facility.

Jan 1, 2008

By David Shuck

On November 1991, Homestake Mining Co. completed the installation of a $5.7-million, 2.7-kt/d (3000-stpd) flotation circuit into the flowsheet of the McLaughlin Mine in California's coastal mountain range, about 113 km (70 miles) north of San Francisco. This addition reduced overall operating costs and improved the gold recovery of the low-grade refractory reserves over that expected from direct cyanidation. In addition, flotation provided a means to generate a sulfide concentrate that is used to supplement feed to the pressure oxidation circuit. The McLaughlin operation started in 1985 as the first pressure oxidation plant for treating sulfide refractory ore. During the mine's short history, efforts have been made to reduce costs and increase production through process development.

Jan 1, 1994

By Jennifer B. Leinart, Otto L. Schumacher

JIM ARNOLD: Our next speaker is Otto Schumacher. He's president of Western Mining Engineering in Spokane, Washington. His company offers services in the area of mining feasibility analysis and publishes Mining Cost Service. Otto's talk will be "Are Metallurgists Overpaid?" [laughter] I know one that's not. [laughter] OTTO SCHUMACHER: I really think it's kind of a dirty trick for Doug to put me up here and pose that question since I'm a mining engineer. However, it's probably most appropriate that a mining engineer address the question because I can be more objective than the rest of you. [laughter] SPEAKER. Otto, do you promise to say something nice about metallurgists? [laughter] OTTO SCHUMACHER: I'll see how much time I have. [laughter]

Jan 1, 1998

By T. C. Eisele

Previous work by the authors has shown that the performance of a flotation column can be improved by the use of horizontal baffles. These baffles prevent axial mixing and also reduce "churning" of the froth by breaking up or preventing the formation of large air bubbles. In this paper, results from tracer experiments are presented that show the effects of horizontal baffles on the reproducibility and stability of the column operation. The baffles prevent random disturbances, such as unusually large air bubbles and turbulence, from rapidly propagating along the height of the column. Because these factors are responsible for much of the variations in column performance between tests, the result is that the horizontal baffles make the column performance more reproducible, with fewer short-term variations.

Jan 1, 1999

By Raimondo Ciccu, Francesco Satta, Marcello Ghiani, Piero Carbini

Nonpolar oils are utilized as collectors in low-rank coals flotation processes. The analysis of the mechanism of the hydrophobic film formation on coal particles permits the identification of the main characteristics that these reagents should exhibit in order to render the process technically and economically efficient. Such requirements - low repulsive energy developed in the interaction with coal particles; limited interfacial tension at the coal-oil boundary; relatively low viscosity and, at the sake time, poor ability to absorb into the coal pores - are found in some binary mixtures of oils having different volumic mass. The features of such mixtures as well as the advantages deriving from their use for the flotation of a Sulcis coal sample and experimentally proven, are described.

Jan 1, 1989

By Edward Finch, William F. Riggs

Selectivity and recovery of many industrial minerals can be directly affected by the carbon length, degree of unsaturation, and melt point of fatty acids used as collectors. Examples of several modifications are provided based on actual experiences of commercial applications. A review of recent history indicates that fatty acid collectors are applicable from C9'C18 in carbon length, however, not for all minerals. The mesh size, density, and surface characteristics of the particular mineral, as well as other related operating conditions, are important in selecting the correct fatty acid configuration. A review of some past programs are submitted as a guideline in the selection of fatty acids and supported by isolated, successful examples demonstrating the effect of carbon length and unsaturation.

Jan 1, 1986

By J. Hanna, J. Jung

Researchers at The University of Alabama have recently developed a two-step method for the treatment of phosphorus sludge. The process includes the bulk removal of phosphorus by physical separation techniques followed by the remediation of the residual P4 in the sludge using a novel, wet, air-oxidation technique known as "HSAD." Tests made on electric furnace, phosphorus sludge samples have demonstrated that an essentially complete and fast removal of the contained P4 can be achieved by the HSAD wet oxidation treatment. Further studies were made to determine the applicability of the two-step process to sludges of different origins, pretreatments, storage conditions and P4 contents. The present work discusses the mechanisms and factors controlling the HSAD, wet, air-oxidation remediation approach.

Jan 1, 1993

By E. B. McNew, J. M. Barnes, A. E. Torma

The applicability of biosorbent materials for the removal of uranium and other heavy metals from synthetic and actual uranium mil 1 tailing (UMT) solutions has been investigated. The biosorbent materials used in this study were barium loaded beads of alginate, alginate-dextran sulfate, alginate-carrageenan, and alginate-xanthan gum. These studies were performed in stirred vessels and packed columns. It was observed that 100 percent of the uranium could be removed from a synthetic solution following 2 hours of contact time in a stirred vessel, and 80-100% of U, V, Mo, Mn, Sr, and Zn could be removed from a UMT effluent solution with a packed column. Kinetic evaluations were performed, using a generalized rate equation, on the biosorption of uranium with these barium loaded beads.

Jan 1, 1992

By M. M. Botz

Cyanidation tailings disposed of in a surface impoundment experience a loss of cyanide due to natural attenuation, which frequently reduces the cyanide concentration to very low levels. Quantifying cyanide losses in terms of impoundment geometry, local weather conditions and feed-solution chemistry has been largely empirical in spite of the fact that, in many cases, mining operations rely on surface impoundments to reduce cyanide to below an internally regulated concentration or below an effluent limitation. To permit a quantitative evaluation of cyanide losses in an impoundment, a computer simulation was developed to estimate the losses of free, weak acid dissociable (WAD) and total cyanide due to dissociation, photolysis and volatilization. Results of the model are compared with data collected for a North American tailings impoundment in 1998.

Jan 1, 2000

By D. T. Maiers, P. L. Wichlacz, P. A. Pryfogle, J. H. Wolfram

The effects of metal solution concentration, biomass density, length of exposure time, and pH were determined for biosorption of molybdenum (Mo) and chromium (Cr) by three organisms. Results indicate that it is possible to sorb Mo and Cr from dilute solutions. Differences were observed in the abilities of an organism to sorb Mo and Cr as well as among respective abilities of the three microorganisms. This suggests an inherent selectivity of the organism which may afford the means to control a sorption-based process. Results also indicate that the metal sorption abilities of these microorganisms depend on duration of exposure, biomass density, solution pH, and the metal concentration of the solution. Each of these parameters suggests an additional means of controlling the sorption process.

Jan 1, 1989

By H. Cho, P. T. Luckie

A study was undertaken to investigate the liberation behavior of coal macerals through size reduction and density separation. It was seen that the liberation of coal macerals could be achieved by size reduction, allowing selective separation of coal organic components. However, the degree of liberation was dependent upon the comminution history. Even for the same fineness, the extent of liberation might not be the same depending on how the material was generated. The liberation of coal macerals was analyzed by examining the liberation index. It was seen that, although comminution produced fine particles enriched in inertinite (primarily fusinite and semifusinite), these particles were less liberated than coarser particles. However, the liberation of macerals increased when all the feed was ground to a finer size.

Jan 1, 1999

By H. Sis, D. Dahlin, S. Chander, C. Summers

Bench-scale selective-flocculation tests were conducted on samples of Florida phosphate and Western phosphate process tailings to recover upgraded phosphate concentrates. After physical and mineralogical characterization, the slurry samples were treated with a broad suite of flocculants with a range of molecular weights and anionic functional groups. Parameters investigated included pH, dispersant and flocculant types, and dose; conditioning parameters and settling times were, for the most part, held constant. Where selectivity was achieved, phosphate minerals remained dispersed, whereas silicate minerals flocculated and settled. Single-stage tests using reagents with low to medium anionic characteristics produced upgraded phosphate concentrates at moderately elevated pH. Two- stage site-blocking tests, in which low-molecular-weight flocculants were used as site-blocking agents, gave improved results.

Jan 1, 2002

By C. W. Matthews

Introduction Screening is defined as a mechanical process which separates particles on the basis of their size and their acceptance or rejection by a screening surface. The key element in this method of particle sizing is obviously the screening surface, the medium that contains the apertures for the passage of the undersize material. This surface must be strong enough to support the weight of the material being screened, flexible enough to yield to the vibrating force applied to it, yet light enough to provide a reasonable ratio of open area to attain a practical through- put. To balance all of these factors is difficult enough. The problem is compounded, however, because screening media are made in a great variety of types, shapes, sizes, and materials of

Jan 1, 1985

By Jan Visman, James W. Parkinson

GENERAL INTRODUCTION Sample collection, preparation and analysis are all steps in a single process designed to provide information about a much larger amount of material than the sample itself. For example, information about the ash content of a unit train load of coal may be derived from a single, relatively small sample of perhaps a few hundred pounds (liters) extracted from the entire shipment. These three steps can be thought of as links in a chain, allowing the simple analogy that the strength of the chain, or, in other words, the value of the information is only as strong as the weakest link. Sample collection, discussed in Part 1 of this chapter, is critical because analytical procedures can do no more than reveal the characteristics of the sample presented to the laboratory. If that sample does not properly represent the population to be characterized, neither will the analysis of that sample. Sample preparation is also a critical part of the chain. Any change in the nature of a sample between the time it is collected and the time it is analyzed will appear to reflect the nature of the population. For example, sample preparation procedures that allow air to partially dry the coal sample before reaching the laboratory will cause the sample analysis to indicate a lower moisture content than the sample originally had. Other changes can be more subtle. Second only to moisture loss, oxidation reactions generally cause the greatest problems. Oxidation of a coal sample can alter surface properties, changing flotation response. In extreme cases, combustion parameters, such as caking or agglomerating properties or mineral composition, such as pyrite content, can change. Water samples can also be altered by oxidation. For example, ferrous iron can oxidize to ferric iron, possibly changing water quality parameters such as pH. Sample analysis, the subject of Part 2 of this chapter, is the final link in the chain. Obviously, no laboratory procedure can correct for problems created by improper sample collection and preparation. At the same time, poor analytical techniques will create incorrect information about the total amount of coal from which the sample was extracted (the population) in the same manner as improper sample collection and preparation. The key to gaining correct information about the population is to view these three steps as parts of a single process. Following proper techniques through only one or two steps of the process will not produce accurate information.

Jan 1, 1991