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By Barry Hunsaker

I cannot help but be reminded, as I stand here today, of my boyhood years and heritage, both of which are inextricably tied to this very valley and are, in a: bay, apropos of the theme of this Keynote Session. I remember the scarcity of people. For example, 48, 000 in Phoenix and 436, 000 in the State in 1930 and 65,000 in Phoenix and 499, 000 in the State in 1940. Today Phoenix boasts a population of over 500, 000 and the State a population of 1, 500,000. I remember the' lack of facilities, goods and services, including gas and electric power. I recall stories of my grandfather who had the freighting or teaming contract to haul all the supplies and generating equipment, by wagon mind you, up the old Apache Trail to Roosevelt Dam. . .a three day trip from the nearest railhead which, by the way, was not Phoenix, for it did not merit a railhead on those days, but the village of Maricopa approximately 25 miles south of Phoenix. I remember chopping firewood, heating wash water on an open fire in a No. 3 wash tub at the rear of the house and doing my school homework by the light of a kerosene lamp just 25 to 35 years ago within what is now a large metropolitan area

Jan 1, 1965

By Tim Cleary, Steve Skelhorn

The 9th Line / 16th Ave tunnels are part of a $700 million expansion of the York Durham Sewage System, north of Toronto. The 15 km of tunnels presented many challenges, including glacial and postglacial deposits, at depths up to 55 m. Due to high hydrostatic heads, the Owner specified EPB tunnelling, however, an alternate was proposed utilising rib and lagging tunnels, combined with a de-watering scheme. State of the art technology was utilised with a new Lovat TBM, incorporating PLC control, soft start water-cooled motors and a head designed to tackle the mixed ground expected. The 9th Line tunnels were completed in 2002. Subsequently the second section of tunnel along 16th Avenue has been awarded to the Joint Venture. This paper presents a case history of the soft ground tunnelling, including design elements, tunnel systems and TBM operations.

Jan 1, 2003

By Brian Stimpson

A recent study by the National Academy of Engineering concluded that if the U.S. Coal Industry is to double production by 1985 it must open 30 new 2,000,000 tons per year surface mines in the eastern states and 100 new 5,000,000 tons per year surface mines in the western states, in addition to major growth in underground mining. Major expansions in coal mining are also planned in other countries. Engineering geology can play an important part in coal mine development, operation and abandonment (Table I), and with the increasing scale of surface coal mining and the requirements of environmental legislation, it seems certain that engineering geology and geotechnics will play a growing role in surface coal mining.

Jan 1, 1976

By A. B. Cecala

Two recent Bureau studies evaluated workers' dust exposures in automated pallet loading processes. The first study involved a Bureau designed dust control system using a push-pull ventilation technique. The unit was shown to reduce workers' dust exposures by 76% during pallet loading at a ground silica operation. A hydraulic lift table was used to automate the bag stacking process; this kept the loading height constant throughout the entire pallet loading cycle. The second study evaluated different commercial automated pallet loading systems. These systems automatically stack the bags onto pallets, shrink wrap the pallets, and deliver the pallets to a fork lift pickup location. Results from a ground silica evaluation site indicated respirable dust samples taken were below the Threshold Limit Value (TLV) as established by the Mine Safety and Health Administration (MSHA).

Jan 1, 1990

An AFM has been applied to study in situ the adsorption of oleic acid on fluorite in aqueous solutions. The AFM images show that fluorite surface becomes smoother with the adsorption of 7 × 10-5 M oleic acid solution at pH 9. Force measurement shows that fluorite is strongly positively charged in water at pH 6, suggesting a neglectable surface carbonation of fluorite. The adsorption of oleic acid at pH 9 renders fluorite more and more negatively charged. The surface morphology change of fluorite as shown by the AFM images suggests that oleic acid chemisorbs on fluorite at pH 9. Increasing temperature can help increase the adsorption of oleic acid on fluorite. It may also improve the lateral polymerization of unsaturated oleic acid on fluorite as suggested by the smoother mineral surface in oleic acid solutions at an elevated temperature.

Feb 23, 2014

By Eleanore L. Nestlerode, James R. Guilinger

In April. 1990 Addwest Minerals acquired the Phillips Ranch sulfur property. The sulfur deposit, hosted by the Permian Castile anhydrite, occurs as two distinct elongate. parallel orebodies within a series of northeast-trending grabens. After completing a positive feasibility study, based, in part. on successful drilling programs by Addwest Minerals and previous operators, the decision was made to place the property into production. Utilizing an existing on-site kasch plant, plus significant portions of the recently purchased Texasgulf Comanche Creek Frasch plant. Addwest is currently constructing an 800 long ton per day Frasch mining facility.

Jan 1, 1992

By J. G. Groppo

In 1992, 48 million tons of fly ash (not including bottom ash, boiler slag and FGD material) was produced in the United States, according to the American Coal Ash Association. Of this amount, 27.2% was utilized; although the percentage of fly ash utilized increased from 20% in 1980, there is significant potential to increase utilization. One of the primary driving forces behind increased utilization is increased disposal costs due to more stringent environmental controls and regulation. Fly ash is classified as a natural pozzolan and finds significant use as a cement additive. It has been found to increase the plasticity of the cement mixture while lowering the amount of mix water needed. In addition to improving leveling and finishing properties, fly ash improves pumpability as well as decreases the heat of hydration of the concrete mix which is particularly important in massive concrete structures such as dams where the concrete needs to cool as quickly as possible. The Loss on Ignition (LOI) of fly ash is an important quality when considering utilization. The LOI is primarily due to the presence of unburned carbon and the standard specifications for the use of fly ash as a mineral admixture in Portland cement concrete are given in ASTM C618-89a. which sets an LOI limit of 6%. However, many states have set a more stringent limit of 3%. The primary reason for the lower LOI specification is that carbon adsorbs air entraining agents which limits freeze-thaw resistance. This is particularly important in climates such as the midwestern US where multiple cycles of freezing and thawing are typical in winter.

Jan 1, 1995

By N. Kuyucak

Uranium ores leached with sulphuric acid typically have poor dewatering properties. Applicability of controlled neutralization where gypsum precipitates as crystalline particles, improving dewatering properties of material was examined. Neutralized material was then dewatered using paste thickener to increase underflow density. The objectives are to maximize water recovery due to water scarcity and to produce suitable cemented paste fill material for optimizing underground ore recovery. Work was performed on acidic slurry samples collected after leaching but before the resin-in-pulp uranium recovery. Controlled neutralization greatly reduced volume of neutralization precipitates giving higher densities and improving the dewatering (filtration) properties. As a result it would be possible to increase the water recycled to the mill. Another benefit is that sulphate in the recycled water was reduced to saturation limit minimizing scaling of process equipment. Additional test work is needed; however, Unconfined Compressive Strength results imply that controlled neutralization increases the strength of paste fill and possibly offers opportunities towards a viable backfill option.

Jan 1, 2010

By M. Howe

This is a study of the impact of cyanide from mining waste on riparian communities, primarily vegetation, near Whitewood Creek, down-stream from Homestake Gold Mine in Lead, South Dakota. Cyanide is used in gold processing and the effluent, until fairly recently, was discharged directly into Gold Run Creek which empties into Whitewood Creek. Vegetation, soil, and water were collected from four different sites over a six month period, and samples tested for cyanide concentration. Data indicate a relationship between cyanide in soil and its uptake by certain plants, also, that the Homestake cleanup effort has made the stream viable again.

Jan 1, 1983

By H. EI-shall

The conventional beneficiation scheme for Florida phosphates involves reverse flotation with an intermediatory acid scrubbing step. A single reagent flotation process, using fatty acids or amine as the collector, would eliminate the scrubbing step along with the other flotation step. This can not only simplify the process flowsheet, but also result in reduced reagent costs. The potential of single reagent flotation of Florida phosphates using fatty acids as the collector was examined in this study.

Jan 1, 1993

By Thomas P. Meloy

Floating "fines" differs from floating "sands" because the fines have a much larger surface area compared to their mass. The forces that arise from this large specific surface the key to understanding the behavior and treatment of fine particles. Though the nature of these forces is not thoroughly understood, enough work has been done to give a qualitative picture of what is happening in a flotation cell. It is the purpose of this chapter to re-examine some of the more, recent theoretical work and-to indicate its importance.

Jan 1, 1962

By M. A. Bartkoski

Today?s surviving companies are being pushed to a heightened level of excellence due to market changes. Therefore, new business strategies must be explored. This paper offers a sequenced plan to retool, empower, and organize the entire team for a common goal. Integrity Process is an operating system that is very comprehensive and is integrated in every part of the business. It relies on a detailed prevention concept intertwined with accountability that produces individual efficiencies and team effectiveness. Integrity Process focuses on the importance between working from commitment motives versus compliance fears. The results are balanced in priority and truly yield a win-win for the owners, management, workforce, and the community. Integrity Process can and is being used in any industry that is challenged to optimize the relationship between people and process.

Feb 23, 2014

By G. R. Brunskill

The molybdenite flotation plant at Magma Copper Company, San Manuel concentrator has been in operation since 1956. In January of 1980 the plant was converted from a hydrogen peroxide - ferrocyanide process to the current sodium cyanide - sodium hydrosulfide process. This paper is an operational review of Magma Copper Company's molybdenite recovery circuit, column cell flotation experience and use of on- stream x-ray flourescence analysis.

Jan 1, 1985

By A. Goulsbral, D. Harrison, R. Dunne

A programme to reduce cyanide consumption at the New Celebration Gold Mine, situated 32kms South of Kalgoorlie, Western Australia, commenced in the latter part of 1990. Cyanide speciation studies at the time identified that the major loss and consequently consumption was due to the hydrolysis of cyanide, The use of artesian hypersaline waters of high magne­sium content on gold plants in Western Australian Goldfields has meant that economically viable operating pH values during cyanide leaching are around 8.9 to 9.5. The high ionic strength in these waters does to some degree retard the hydrolysis reac­tion. Notwithstanding this, the formation of hydrogen cyanide and its loss due to volatilisation is the cause of the major loss of cyanide on most gold plants in the Kalgoorlie Goldfields. This paper discusses the aspect of oxygen addition during cyanide leaching to decrease cyanide consumption and increase gold recovery.

Jan 1, 1996

By K. A. Natarajan, Namita Deo

The interaction of Bacillus polymyxa and minerals such as hematite, corundum and quartz resulted in significant surface chemical changes, both on the cell surfaces and on the interacted oxide minerals. After such treatment, quartz was rendered relatively more hydrophobic, while hematite and corundum were rendered more hydrophilic. Biopretreatment was observed to be beneficial in the separation of silica from hematite and alumina by both selective flocculation and flotation. The possible role of bacterial adhesion and metabilites in the biobeneficiation process is illustrated.

Jan 1, 1998

By F. S. Knoll

Magnetic separation employing superconducting technology is now accepted within the Kaolin processing industry, proving the value of this technology and its ability to operate reliably even at the most remote site. Developments in superconducting magnet engineering, including cryogen free operation, combined with experience in mineral processing enables new forms of Wet and Dry superconducting magnetic separation to be developed. Applying the high magnetic force advantages at 5 T else available from such magnets to other materials is now a reality. High magnetic force mineral separating system developments are reviewed allowing the mineral processor to take advantage of a technology that is no longer confined to the laboratory.

Jan 1, 1997

By E. Taskin

Diasporic bauxite from the Mugla-Milas region was mechanically activated in a planetary mill for different activation times and the structural changes were examined by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and specific surface area analysis (BET ? Burnauer, Emmett and Teller). Non-activated and activated bauxite samples were leached directly in alkaline (Na2O) solution at atmospheric conditions and the activation procedure led to the amorphization and structural disordering of the diasporic bauxite structure, which increased the dissolution efficiency. Effects of milling speed, liquid/bauxite ratio and leaching time on alumina extraction in direct alkaline leaching of diasporic bauxite were also studied. The alumina extraction was ~7% for non-activated bauxite and ~70% for activated (75 minute) bauxite. Key words: Diasporic bauxite, Mechanical activation, Alkaline leaching, Alumina extraction

Jan 1, 2009

By R. J. Bridwell

Acid mine drainage (AMD) occurs in high sulfur coal and heavy metal mining environments. We show remediation methods using 3D numerical ground water flow models and chemical kinetics of pyrite oxidation for acid leaching of pyrite during air and ground water flow. A recently developed numerical model couples air and water flow with kinetics of iron-reactive bacteria, oxygen transport, specific chemical reaction rates, and pyrite oxidation to calculate migration control of pollution. A model is presented which considers diminution of acid mine drainage in pyrite rich ore bodies by raising the potentiometric surface through a vadose zone to reduce acid mine drainage. A ground water model is presented of an initially saturated mountain, containing an adit, with a sloping ground water table. Ground water recharge consists of snowfall and normal precipitation. Simulations indicate that the historically open adit creates a desaturated mountain above the adit. Significant air saturation ranging from 10-90% oxygen can occur to depths of the adit (-270 m). Remediation consists of plugging the adit, which fill s adit and mountain with water from recharge. Plugging the adit required <10 years for resaturation and rise of the water table in the mountain.

Jan 1, 1994

By E. Farrokh

CSM and NTNU models are among the most commonly used models in TBM performance evaluation. Due to increasing application of TBM in different tunneling conditions, modification became necessary for these models. Sensitivity analyses on these two models indicate that both models are very sensitive to machine characteristics. Analyses performed on CSM database for cutter load and penetration rate prediction indicate while the r-square of the CSM model is reasonably high for the predicted cutterload, the r-square value for the penetration is low. In order to increase prediction capability of CSM model for penetration rate the model was reevaluated using non-dimensional analysis and the original database of Colorado school of mines. NTNU model is evaluated using Monte Carlo simulation and regression analysis. The results of analyses indicate that the majority of the variation of the penetration in NTNU model can be explained by only three parameters. This might indicate that the effects of other factors are overshadowed and it is worthy to reevaluate NTNU model using original database and more updated statistical methods to avoid overlapping of different parameters correlations.

Feb 23, 2014

By O. M. Johnson

Barite and bentonite are the two principal components of drilling fluid systems used in the petroleum industry for oil and gas well drilling with rotary-type rigs. Approximately 87 percent of the world&apos;s annual production of barite is used in drilling applications. Of the worldwide production of bentonite, an estimated 30 percent is used. The drilling fluid, or drilling mud, to which barite and bentonite are added, performs five distinct functions: Lubrication-The liquid phase of the drilling mud lubricates the drill bit, preventing premature failure of the cutting edges and bearings. it also helps to soften the formation being drilled. Cuttings Removal-A mud system must be able to carry rock cuttings broken loose by the bit up to the surface where they can be removed by mechanical or chemical methods. The fluid&apos;s ability to perform this function depends upon maintaining a proper balance between the rate of circulation of the fluid and the colloidal properties required to entrain the cuttings in the mud to prevent their settling to the bottom of the hole. Hole Stability-The pressure exerted by the mud against the wall of the bore hole prevents the collapse of the uncased portions of the hole. Downhole Information-The fluid characteristics of the mud should be such that good cuttings samples, cores and electric logs may be obtained to help evaluate a well&apos;s productive zones and potential. Control Oil, Gas and Water Flows-It is essential that a drilling fluid offset any pressure from naturally occurring formation fluids in order to prevent a potentially wasteful and dangerous blowout.

Jan 1, 1980