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An atomic force microscopy (AFM) has been applied to study the adsorption of collectors on mineral surfaces in a copper/molybdenum flotation system. AFM images show that collectors absorb on chalcopyrite surface in patches at pH 11. A study of temperature effect on surface morphology excludes the possibility that these patches are nanobubbles forming on hydrophobized mineral surface. Hydrocarbon oil absorbs on molybdenite quickly, while KEX (potassium ethyl xanthate) has little affinity for molybdenite. Pyrite is much more reactive in water and its surface is easily coated in Ca(OH)2 solutions at pH 11. Based on the obtained AFM images, the adsorption of chemicals on mineral surface and its impact on copper/molybdenum flotation were discussed.

Jan 1, 2012

By R. L. Wooten

When discussing what Coal Mine Safety in the future will be, it is important to examine three areas which at present provide significant parameters to the industry. These three areas are: 1) Safety improvements in mining equipment; 2) Labor-management relations; and, 3) The politics of coal mine safety. EQUIPMENT Over the past several decades significant safety improvements have been made in the types of equipment now in use in most operations. Many of these improvements have evolved through mandates from either the U. S. Bureau of Nines, MESA, MSHA; and in some instances, the states. Cabs and canopies are examples of federal mandates while the use of ATRS initially was a state mandate.

Jan 1, 1985

By W. D. Bullock

The King-Beaver mine of Asbestos Corporation Limited operates an open pit in the city of Thetford Mines, Quebec. The approximate loca-tion of the open pit is at Latitude 46° 02' North and Longitude 71° 20' West. The general topography is 1020 feet above sea level. Thirty-six percent of the company's scheduled asbestos ore production, for the Thetford Mines area, comes from the King-Beaver pit. The pit operates 24 hours a day, six days a week. Normal production is 10,500 tons of ore per day at a waste to ore ratio of 2 to 1. The remaining ore requirements are mined from the King-Beaver underground mine and the British-Canadian mine.

Jan 1, 1980

By W. L. Chen

In the United States hydraulic cyclones have been used for thickening, classification and cleaning in coal preparation plants for many years. The cleaning cyclones presently in use are based on using a "heavy medium", such as a fine magnetite and water pulp. The latest addition to cleaning cyclones is the one which uses ?water only?, or simply called "Hydrocyclone". Just as was the heavy medium cyclone, the hydrocyclones were originated in the Netherlands (1, 2). Plants using hydrocyclones were built in Europe (3) and test plants were erected in Canada (4, 5, 6) and India (7). Roberts and Schaefer Company has built four plants using hydrocyclone circuits. One additional plant is in the process of construction.

Jan 1, 1965

By K. T. Mau

Hawaii is located approximately 2,500 miles from the mainland, but has basic needs for its thriving developing community. Cement is one of these needs Cement production in Hawaii is not without handicaps. The necessary raw materials are practically non-existent except for limestone. Even at that, the available limestone is marine in origin, coralline in nature and amorphous in characteristics - unlike calcite which is normally the calcium carbonate source for cement manufacture. There is no clay or shale for the argillaceous portion of cement raw mix. Hawaii being volcanic in origin is too young geologically for clays and shales to evolve and whatever there is, most likely is washed into the ocean.

Jan 1, 1982

By J. D. Miller, J. Hupka

Environmental applications of the air-sparged hydrocyclone (ASH) technology are presented. The original ASH design used porous sintered steel or porous polyethylene tubes as spargers. To diminish/prevent plugging and to reduce pressure head loss in the gas path a wire screen sparger and new hydrocyclone design have been developed, which allows for wide application of the technology to solve environmental problems and to be used as a chemical reactor. Field and laboratory trials have shown that the ASH technology might be preferred for the stripping of volatile organic compounds WOC) from contaminated water. The ASH has also been developed for absorption of SO2, toluene vapors, and for the recovery of cyanide.

Jan 1, 2005

By A. C. Kunkie, C. J. Marshall

Highly delaminated muscovite mica products (WG-1 and WG-2) have been developed by J.M. Huber Corp. The micas are characterized as a 325-mesh product having high brightness and very narrow particle size distribution. At 40% loading in polypropylene, WG-1 mica provides substantial improvement in tensile modulus and equal tensile strength to unfilled polymer; in high-density poly- ethylene (HDPE), WG-1 provides four times the tensile modulus and a 50% increase in tensile strength over unfilled polymer. Surface modification of the water-ground mica (SM ™) provides substantial improvement in tensile strength over untreated mica at greater than 20% loading in polypropylene; in HDPE, tensile strength is twice that of unfilled polymer.

Jan 1, 1988

By Kim McKnight

Dupont has successfully incorporated a Floatex Density Separator into its wet-gravity operations for the recovery of zircon from titanium tailings. Results indicate that the Floatex achieved a zircon recovery of approximately 95% while rejecting similar amounts of quartz and other gangue minerals. Additionally, a unit capacity approaching 16 tonnes/hr/m2 was achieved. Results also show that the alumino-silicates can be separated into other product streams that will further improve process economics and minimize waste material. The improved plant feed grade provided by the Floatex has allowed for either an increase in overall plant capacity and/or final product grade. This paper will present the findings from the in-plant study.

Jan 1, 1996

Cost reduction programs can focus on total cost or unit cost, but unit cost is usually the principal objective. The production cost per unit is: [Unit cost = Total cost Production volume] Consequently, any activity that reduces the total cost or increases the production volume will reduce the unit cost. Production volume is increased by (1) maximizing the availability of the production equipment and (2) maximizing equipment performance during periods of operation. Most operations managers routinely focus on volume because the factors influencing volume are generally well understood and congruent with the managers' technical skills. In fact, production volume (as a percentage of maximum achievable capacity) is widely recognized as one of the most significant measures of operational performance.

Jan 1, 1999

By Allan D. Fernie

Many long conveyors, 2 - 20 km plus, have been installed over the past 10 years. Conveyor belt life, depending on the conveyor length and material handled, will generally range from 10 - 15 years. To replace long conveyors splicing one or two rolls into a conveyor run on an intermittent basis can be prolonged in an operating system involving considerable downtime and scheduling problems. This paper presents some of the methods used to- date and highlights forward planning for such an event. Special belt handling equipment required and the execution of a belt change operation are described in detail. Wright Engineers Limited have worked in collaboration with Canada Conveyor to design and implement the methods described herein.

Jan 1, 1993

By K. Hanumantha Rao, K. S. E. Forssberg

The limestone deposit of Gâsgruvan, Sweden contains around 89.2 per cent of calcite. Conventional and column flotation studies have been carried out using sodium oleate and modified fatty acid collectors in the presence of sodium silicate modifier. The effects of collector and silicate concentrations, and particle size on the flotation response of calcite have been investigated. The results have been discussed in comparision to the performance of conventional and column flotation cells. The feed size is found to be a significant factor to achieve a high grade calcite concentrate either by conventional or by column flotation. The loss of selectivity at fine particle sizes is examined using a modified DLVO theory.

Jan 1, 1995

By Kalliat T. Valsaraj, Louis J. Thibodeaux

A mathematical model is described for the transfer of hydrophobic compounds from aqueous to an immiscible organic phase using fine bubble aeration; the process otherwise known as "solvent sublation" an adsorptive bubble separation process. The limitations of the model are explored by simulating experimental results both for a batch scale process and a continuous process. The qualitative predictions of the model with respect to the influence of the organic layer (mineral oil) are tested by performing experiments using chloroform and 2,3,6-trichloroanisole as hydrophobic compounds in the aqueous phase. The continuous process is seen to be limited by the requirements of fine bubble generation and the ratio of influent feed rate to air flow rate.

Jan 1, 1989

By E. J. Berentsen, R. F. Nanna, D. Dell’ Elce, R. Lougheed

Apollo Gold’s Black Fox project is located 10 km (6.2 miles) east of Matheson, Ontario, Canada, on Hwy 101 East It is located within the prolific Destor Porcupine Fault Zone, which is also the host for the Dome and Hollmger mines to the west and the Holt and Holloway mines to the east. The local host rocks are intensely deformed and carbonized ultramafic volcanics, pillow basalts, syenitic felsic intrusives and argillaceous sediments. Gold occurs with pyrite and as spectacular specimens in native form. Past production accounted for a total of 195,337 oz (6,075,606 g) of gold. Apollo Gold Exploration, Inc. is conducting an intense drilling program aimed at expanding the reserve base.

Jan 1, 2004

By Thomas F. Pedersen, J. Jay McNee, Alan J. Martin

Field sampling was conducted in Lake Junin, Peru in order to assess the post-depositional reactivity of the highly contaminated lake sediments. High resolution profiles of dissolved Fe, Mn, SO42- and H2S across the sediment-water interface illustrate that the organic-rich sediments in the main basin become anoxic within several millimetres of the sediment-water interface. These permanently submerged deposits in the main basin serve as a diffusive sink for dissolved Zn and Cu. Conversely, the periodically unsaturated deposits in shallow areas are characterized by the remobilization of Zn and Cu in the deep acidic (pH < 4) pore waters, resulting in the release of these metals to the overlying water column.

Jan 1, 2000

By Catherine M. Dentan, Yosry A. Attia

The presence of finely divided carbonaceous matter, particularly graphite, in gold ores, adversely affects the adsorption - recovery of gold by activated carbon from cyanide solutions of such ores. Competitive adsorption of gold by graphite and other carbonaceous matter, is thought to be responsible for this deleterious effect In this study, adsorption of gold cyanide complex AU(CN)2- by the activated carbon used in carbon-in- pulp or carbon-in-leach processes, was compared with that by graphite which was chosen to represent the carbonaceous matter. Similar adsorption studies were made with gold chloride complex AuC14-. Correlation of adsorption with surface characteristics and thermodynamics were presented in detail, and a flowsheet for graphite-in-leach was proposed.

Jan 1, 1990

By Richard R. Klimpel

This paper discusses some important industrial interactions between size reduction and downstream froth flotation processes. Experience gained at the industrial level is clearly indicating that how size reduction circuits are designed and/or operated can have a significant impact on froth flotation beyond normal considerations of particle size, liberation, etc. Three specific interactions will be discussed: 1) the impact of steel grinding media versus autogeneous grinding on the efficiency of sulfide mineral flotation with varying thiol collectors and water sources; 2) the importance of appropriately utilizing the electrochemical window that is created in the grinding to enhance sulfide mineral recovery by froth flotation; and 3) the interaction of particle size distribution with collector dosage and frother type.

Jan 1, 1995

By J. M. Kruger

High-resolution ground-penetrating radar (GPR) was used to image the near-surface extent of two exposed Late Cretaceous kimberlites intruded into lower Permian limestone and dolomite host rocks in northeast Kansas. Six parallel GPR profiles identify the margin of the Randolph 1 kimberlite by the up-bending and termination of limestone reflectors. Five radially-intersecting GPR profiles identify the elliptical margin of the Randolph 2 kimberlite by the termination of dolomite reflectors near or below the kimberlite&apos;s mushroom-shaped cap. These results suggest GPR may augment magnetic methods for the delineation of kimberlites or other forceful intrusions in a layered host rock where thick, conductive soil or shale is not present at the surface.

Jan 1, 1997

By C. D. Harrison, G. S. Stallard

The 199O Clean Air Act Amendments specify national objectives for reducing sulfur dioxide emissions from coal fired power plants. System-wide reductions can be achieved by combining various emissions control technologies and allowances, or compliance credits, that can be purchased, sold or traded. As part of the Coal Quality Expert development project funded by the US Department of Energy and the Electric Power Research Institute (EPRI), Black & Veatch has developed an interactive computer tool, the Acid Rain Advisor (ARA). Through this program, integrated, system-wide compliance plans are generated by comparing the costs and emissions reduction benefits of emissions allowances and various SO2-control technologies (coal cleaning, fuel switching, scrubber retrofits, etc.)

Jan 1, 1993

By V. W. Skema, M. W. Smith

Pennsylvania has 4,000 km (2,500 miles) of streams that do not meet water-quality standards due to acid mine drainage (AMD), making AMD the greatest cause of water pollution in the state. The problem is mainly caused by abandoned coal mines. To abate AMD, Pennsylvania is using a watershed-based approach that includes remining as a key component of a comprehensive restoration strategy. The Tangascootack Creek Water-shed was targeted for AMD restoration through remining. Geologic mapping and overburden data were analyzed using Earth Vision software to identify areas of coal reserves that could be remined to improve water quality. Incentives are offered to encourage mining in these designated areas.

Jan 1, 2002

By John Reynolds, Robert Sloan

The Escondida copper mine is located in the northern Atacama Desert of Chile at an elevation of 3,050 m. approximately 160 km southeast of the port of Antofagasta. The mine is a joint venture between BHP-Billiton, Rio Tinto, a Japanese consortium and the International Finance Corporation. The most recent expansion, Laguna Seca, has increased the total capacity to the level of 220,000t/d ore throughput. The ore body, a typical porphyry deposit, is situated on the major Chilean west fissure fault system and contains primary sulphide ore grades between 0.6% and 2.0% copper. Primary sulphide mineralization consists of chalcocite pyrite, chalocopyrite, bornite and covellite. Significant copper oxides overly the sulphides in many areas.

Jan 1, 2005