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By Y. Wang, E. Forssberg, R. J. Pugh

The coagulation of dispersed ultrafine weakly-magnetic oxide mineral particles (e.g., natural hematite and chromite) in an external magnetic field can be described by interparticle forces. Essentially, coagulation occurs when the short-range London-van der Waals interactions and the long-range magnetic forces outweigh the stabilizing electrical double-layer repulsion. Using the classical colloid chemistry theory, the various components of the potential energy for different-sized particles at a series of ionic strengths and magnetic field intensities were calculated. The results of this theoretical analysis were then related to the results obtained from experimental studies in which the magnetic field-induced coagulation of the ultrafines of natural hematite and chromite in aqueous suspensions were investigated using a laboratory-scale electromagnetic solenoid. The experimental results relate the coagulation process (as determined by magneto-sedimentation analysis) to the particle size, the slurry pH and the external magnetic field. In the magnetic fields, the maximum coagulation occurred near the pH of zero-point-of-charge (pHzpc) of the minerals (where the electrostatic double layer repulsion was reduced to a minimum) enabling the particles to enter the "primary minimum" energy sink. On the other hand, in cases where the electrostatic repulsion was not suppressed, the long-range magnetic forces enabled coagulation to occur in the "secondary minimum." This caused the formation of chains that appeared to be relatively stable during sedimentation.

Jan 1, 1995

By Lane White

The nature of the new Mining Law in Mexico, how it works and its implications for foreign investors were discussed from a variety of points of view by speakers participating in SME's special programming on Mining in Mexico at its An¬nual Meeting in Albuquerque, NM Feb. 14-17, 1994. Following are summaries of three papers whose primary objective was to give foreign investors some insight into the nature of doing business under the current Mexican Mining Law and its regulations. Lane White, Publisher.

Jan 1, 1994

By Eric Forssberg, Benny Andreasson

The paper describes experiments to stabilize mineral processing waste materials for use in construction. Fine mineral processing wastes from various mines have been mixed with binders and compacted. As binders blast furnace slag and other materials have been used. Experiments have been made in laboratory scale and in large scale. The results have been evaluated by means of determinations of compression strength and the modulus of elasticity. The paper also describes some experiments in laboratory and large scale to use stabilized mineral processing wastes for back filling in cut and fill mining.

Jan 1, 1992

By O. Olajide, E. H. Cho

A laboratory study of the jigging process with Pittsburgh seam coal has been conducted. The laboratory-scale Baum jig used in this study was a McNally-Norton LO30X Right Hand Model Baum jig with an effective screen area of 0.186 m2 Feed material was prepared by selecting a size range from 6 mesh to 1.91 cm. Solid feed rates were 27.2 kg/min and 32.7 kg/min. Water flow rates were varied from 37.9 to 94.6 L/min. It has been found that smaller particles give higher values of density of separation and lower efficiency of separation. Increasing water flow rate increases the discharge rate of clean coal at a constant solid feed rate. It appears that the efficiency of separation increases by increasing water flow rate up to a certain value, and then levels off upon increasing the flow rate further.

Jan 1, 1988

By Jerry Harrington, Brad Wigglesworth, David C. Beling

Commercial operations at the open pit, heap leach Crofoot Mine commenced in April, 1988. Approximately 13,600 tonnes (15,000 st) of low grade pregnant solution are treated daily using a Merrill-Crowe circuit. Acceptable gold recoveries from these low grade solutions can be obtained by optimizing solution pre-treatment prior to zinc addition.

Jan 1, 1990

By I. M. Eitani, M. Karmis

Ground control presents the most serious problem in underground thick seam mining. In addition to parameters such as depth thickness and inclination of the seam and nature of the coal and the immediate strata, the stress interactions caused by the mining sequence must be carefully evaluated and understood, if safety and productivity objectives are to be fulfilled. In this paper, the most widely-accepted thick seam coal mining methods are reviewed and suggestions are made for future work pertaining to ground control problems.

Jan 1, 1981

By J. K. Wolski

This paper addresses the effects of using jet fans as booster fans in mine ventilation networks. A method was developed to determine the pressure generated by jet fans using the momentum theory. The influence of a reduction cone and other ventilation parameters on the jet fan pressure was analyzed. Verification experiments conducted in the Waldo Mine are described. Examples are given to demonstrate the conditions for the effective use of jet fans.

Jan 1, 1998

By Juergen Loroesch

Since the introduction of Peroxide Assisted Leach, PAL™, in the gold mining industry three years ago, seven plants in Australia and South Africa have successfully employed this process. Significant increases in the gold extraction rate are often accompanied by savings in cyanide. These applications are summarized in an overview which helps to define the requirements for a technically and economically successful PAL operation, based on mineralogical composition, operating parameters, and various design and plant features. PAL has a well-defined field of application which has to be differentiated from competitive oxygen leach techniques.

Jan 1, 1990

By H. Bogart

The Golden Sunlight Underground Mine located near Whitehall, Montana was portalled from the bottom of the existing Golden Sunlight Pit in July 2002. Gold was mined by sublevel stoping in the larger ore zones and longhole back stoping in the narrower ore zones. The stopes varied from 30 feet to 100 feet in width, extended up to 200 feet in height, and were completely unsupported. Underground production averaged 1,500 tons per day with a staff of35 people. The mine operated with a break-even cut-off grade of0.080 ounces per ton.

Jan 1, 2004

By W. L. Han, Y. D. Zhang, X. C. Li

Meta-systhetic technique for large systems engineering has been placed on the agenda. The meta-systhetic A1 approach should involve the integration of digital and knowledge info, from qualitative to quantitative analysis, etc. Some algorithms of meta-systhetic technique such as ANN-ES and GA-ANN are introduced. A case study follows - mining conditions evaluation by meta-synthetic A1 methods, including: setting up the structure of evaluation indexes system, deciding their grade of membership by ANN-ES algorithm; determining the weight values of evaluation factors by GA-ANN algorithm; and developing the integrated evaluation model.

Jan 1, 2002

International Technology for the Nonferrous Smelting Industry, by T. K. Corwin et al., Noyes Data Corp., Mill Road at Grand Ave., Park Ridge, NJ 07656, 413 pp., cloth, $36-Describes current and new production processes, and pollution control technology, in the primary nonferrous smelting industry in the US and abroad. The methods described are intended to reduce costs, increase production, and lower pollution levels. Techniques used in copper, lead, and zinc smelting are emphasized and, whenever possible, the authors describe pollution control practices.

Jan 7, 1982

Successful longwall gate entry design requires control of vertical and horizontal stresses. Vertical, or overburden, stresses are most severe in the tailgate where they are concentrated by longwall panel extraction. Horizontal stresses can also be highly destructive but they are less well understood. This paper discusses measurements of in situ horizontal stress fields in the eastern United States, experience with horizontal stress in longwall mines and methods for predicting and controlling horizontal stresses. The information presented was collected through site investigations at 45 US longwalls and an international literature review.

Jan 1, 1992

By Mohammad Ranjbar Hamghavandi, Mohammad Ranjbar, Zahra Manafi, Mohammad Hassan Fazaelipoor, Mahin Schaffie

The present study introduces a new approach to understand the copper dissolution rate and to find an adapted mathematical statement for particle shrinkage rate in a batch bioleaching system. Four size classes of a chalcopyrite concentrate, namely [D1 : (−54 + 44)μm, D2 : (−44 + 38)μm, D3 : (−38 + 25)μm and D4 : (−25)μm], were used in the batch bioleaching tests by applying a mixed culture of moderately thermophilic microorganisms. The pulp density and temperature were 8 (%w/v) and 50 °C, respectively. Findings delineated that the bioleaching time can be divided into two specific time intervals: first, the surface reactions were the prevailing controlling step; second, the prevailing mechanism was diffusion through the product layer, whereas the overall rate of the process may be related to both through a Q factor using a mixed model. A mathematical model was developed based on particle size distribution (PSD) and a kinetic model. Experimental validation of the mixed model was accomplished by the representative sample with d80 = 54 microns. Results showed that the PSD of the specific sample was in good agreement with Rosin–Rammler function. Besides, the simulation result of the conversion fraction had the best conformity with the experimental data (with a maximum error of approximately 7%). This paper should be considered as an initial part of a larger, global model for chalcopyrite concentrate bioleaching.

By S. K. Kawatra, R. A. Seitz

Nonpolar hydrocarbon oils are commonly used in the flotation of minerals to fulfill a number of roles. These roles include reducing overall reagent costs by replacing part of the collector addition, improving coarse particle recovery without reducing selectivity, as well as several others. This paper will cover the types of oils which are available, their physical and chemical characteristics, and the effect of these characteristics on the function of hydrocarbon oils in flotation. In addition, techniques for improving the behavior of oils will be discussed.

Jan 1, 1986

By Donald H. Sargent

This paper focuses upon the changing character of the market for Western bentonite, and upon transportation methods and costs affecting this market. The basis for the data in this paper, in addition to public sources of information such as federal and state government agencies and the open literature, was a program of 57 face-to-face interviews with individuals knowledgeable in the bentonite production, consumption, and transportation industries. The study was performed in 1974 and 1975 by Versar Inc., for the Bureau of Land Management, Department of the interior.*

Jan 1, 1979

By Pertti Koivistoinen

There are many grinding schools in the mining world, which claim their grinding method to be the best possible - and still the methods concerned vary a great deal. Some of them have multi- stage crushing and only single stage grinding while in others crushing may be nominal, but grinding can be very complicated. - In this presentation firstly the nine most common comminution circuits will be analyzed. Then results from a pilot scale test series will be reviewed, in which nickel ore ground by four different comminution methods was fed to a common flotation treatment.

Jan 1, 1995

The solution mining review did not arrive in time for publication in the May issue. The term solution mining is commonly used to refer to heap leaching, dump leaching, in situ mining and bore hole slurry mining technologies. The US Bureau of Mines is continuing with research in these areas. Commercial application of these technologies is progressing. There is an ongoing cooperative research project between the Bureau of Mines and the Santa Cruz Joint Venture to evaluate in situ copper mining at a field site near Casa Grande, AZ. The project is currently in the environmental permitting stage. The Bureau is preparing an environmental assessment for the project as part of the National Environmental Policy Act. The Bureau is also continuing with laboratory experiments to study the leaching characteristics of atacamite ore from the field test site, as

Jan 1, 1993

By J. D. Raulerson, R. P. Farias, G. A. Gruber

A flotation process has been developed to successfully treat ore from the Santo Domingo phosphate deposit in Baja California Sur. The ore contained less than 4% P2O5 with quartz, silicates, and carbonates as gangue minerals. Flotation of the low- grade feed in seawater required that the conventional Crago process, comprising direct anionic flotation, deoiling, and inverse cationic flotation, be augmented by an anionic cleaner flotation step, phosphate depression, and a calcite flotation step.

Jan 1, 1988

By Fathi Habashi

At the Duisburger Kupferhütte plant in Germany, pyrite cinder is collected from the sulfuric acid manufacturers in that country and processed to recover the nonferrous metals contained in the cinder, before charging it to the blast furnace for iron recovery. A typical analysis of the cinder is given in Table 9-1. The pyrite cinder is mixed with NaCl and treated continuously in a multiple hearth furnace. The evolved gases are scrubbed with water to form a weak acid which is used for the leaching process. Each batch requires about 2 days for leaching. The concentrated leaching solution obtained in the first 15 to 20 hr is sent for copper recovery, while that subsequently obtained, being poor ill metal content, is recycled. The residue, called purple ore, now a high-grade iron ore (61-63 % Fe); is sintered and delivered to the blast furnace.

Jan 1, 1970

By C. Manea

During exploration and exploitation of complex ores, waste dumps that contaminate severely the environment and in particular soils, are genetated. The most hazardous pollutants are heavy metals and metalloids (e.g As, Mo, Pb and Cu) as well as radionuclides (e.g U and Ra). Ecological remediation aims, among others, at decontamination of soils by preserving important properties as soil fertility.

Jan 1, 2008