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By Mehrotra G. M, Frohberg M. G

Based on the concepts of statistical thermodynamics of athermal mixtures, an approach is developed which is capable of quantitatively explaining the thermodynamic properties of binary silicate systems. Expressions for the ionic fractions of various anionic linear and nonlinear chain polymers are derived. The developed expressions for free energy of mixing are tested by applying these to the system PbO-SiO2. The ionic fractions of various chain polymers in this system are calculated. The two cases, namely, of linear and nonlinear chain polymers are compared with each other.Limitations of earlier models are pointed out.

Jan 1, 1975

By T. S. Seleka

Laser surface melting has been conducted on a 304 stainless steel (SS) with the aim of enhancing pitting corrosion resistance of the material. This process involves rapid melting of the material?s surface followed by rapid solidification to refine the microstructure. This includes the dissolution of inclusions such as MnS, FeS, CrxCy, and other minor constituents. The microstructures as a result of laser treatment were observed by means of optical microscope and also confirmed by the XRD. The glow discharge optical emission spectroscopy (GDOES) was utilized for chemical analysis. Changes in hardness were observed by using a Vickers microhardness tester. Pitting corrosion tests on laser treated and untreated samples were conducted according to ASTM G48-92 to evaluate mass loss and pitting morphology. Laser surface melting improved the pitting corrosion resistance of this material in a chloride-containing environment.

Jan 1, 2007

By Jeffrey D. Thatcher, Debra W. Struhsacker

With the burgeoning development of precious metals heap leach mining projects throughout the country regulatory agencies are beginning to take a closer look at the short-and long-term environmental consequences of heap leach mining. This increase in regulatory review is occurring on federal, state and local levels, and is affecting both large- and small-scale mining developments. Small-scale mining developments are receiving especially critical regulatory scrutiny because in the eyes of some regulatory agencies, small developers lack the credibility automatically accorded to major mining companies. This is due in part to a bad image of small miners based upon past environmental problems and permit violations caused by a few, small operators. The proponent of a small mining development thus faces special problems during the project permitting process, and must convince the regulatory authorities of his company's ability and commitment to plan, develop, and decommission a mining operation in compliance with environmental regulations. Not only must the small developer have a thorough understanding of the regulatory requirements affecting his project, he must also devote considerable effort to careful internal planning in order to produce a well organized approach to project permitting. The importance of proper planning cannot be overstated. Project planning is key to convincing the regulatory agencies that the small miner is capable of developing a viable project. More- over, the economics of a small mining project demand permit acquisition at modest cost and in a timely fashion. A well planned permitting effort will thus ensure that permits are received within budget and on schedule. This paper will review the federal, state, and local permitting requirements for heap leach projects, and the variability of these requirements from state to state. The environmental assessment process for projects developed on public lands, and the acquisition of zero- discharge water quality permits, air quality permits, and local special use permits as they apply to small mining developments will be discussed. The paper will conclude with a review of project decommissioning and cyanide neutralization requirements and their implications for small-scale heap leach projects.

Jan 1, 1987

By John Brennan

OK, I’ll admit it: I’ve always been a big Monty Atwater fan. Not only is the man credited with being the father of modern avalanche forecasting and safety in the United States, but he is also responsible for developing the avalauncher. Through its more than 40-year history, the avalauncher has gone through many changes yet continues to prove its worth in avalanche mitigation work.

Jan 1, 2007

The district specially referred to in this paper comprises the very gently sloping country extending from the western shores of Port Phillip from the mouth of the Yarra to Footscray along the Bacchus Marsh railway to near that town thence in a southerly direction to the Little River, and along that river to the coast, 1 as may be seen on the accompanying map. Almost the whole of this area is covered by volcanic rocks, consisting of pumerous sheets of basalt, which have been poured out of various volcanic hills in the districts, such as Mts. Atkinson and Cotteril, near Melton; Mt. Maryand Bald Hill, 12 and 16 miles respectively N.W. of Werribee; and vents in different parts of the parishes of Tarneit, Mouyong, Mooradoranook, Pyweitjorrk, and Derrimut. These volcanoes were in an active state of eruption during a late period of the earth's historyprobably the late Pliocenll, or still younger Pleistocene.Occupying a narrow strip of country, for most of the distance along the coast from Williamstown to past the mouth of the Little River, there occur deposits of still younger age, belonging to the Recent period. These lie on the basalt, and extend for distances varying from a few chains to more than a mile back from the beach. They comprise superficial deposits of blown sand, and raised beaches, composed of marine sands...

Jan 1, 1902

By M. R. Pickus, I. W. Pickus

ORDINARILY age-hardening is thought of as being associated with a limited solubility of one metal in another. Much less has been written about the type of age-hardening that attends the formation of superstructures. Solid solutions generally have a disordered or random arrangement of atoms; that is to say, in a unit cell, such as that of the face-centered cubic lattice, there is no distinction between atomic sites. Atoms of a given metal may occupy cube corners or face centers. Under certain conditions, however, some alloys develop what is known as an ordered structure. In this case, cube corners would be occupied by only one type of atom and face centers by another type, Associated with this ordering process are many interesting changes in physical and electrical properties. Moreover, in many instances the alloys become susceptible to age-hardening. From the evidence now to be described, it appears that age-hardening in 14-carat gold alloys is due to the formation of both a super-structure and a precipitate. Alloys of the metals gold, silver and copper were known in antiquity. The available knowledge regarding their constitution has been ably summarized and extended by Sterner-Rainer,1 Janecke,2 Carter,3 Wise,4 and Coleman.5 Despite the long familiarity with these alloys and the numerous investigations of their properties that have been made, there is still much that remains unexplained. It has been known for a long time that the hardness of these alloys is closely related to the rate of cooling, Similar changes have been observed in the binary gold-copper system,6 one alloy of which corresponding to the formula Cu3Au, has been the subject of a careful and competent report by the English investigators, Sykes and Evans.7 They have established the fact that the shift of atoms from the ordered to the disordered condition takes place in some critical temperature range. At temperatures above the critical range the structure is random, and at temperatures below it the structure is ordered. No difference between these two structures is revealed by the microscope. Both have a face-centered cubic lattice and complete solubility, so that there is no evidence to suggest that the changes in properties are associated with a phase change, The more slowly the alloy is cooled, the higher is the degree to which the ordering process proceeds and the more marked is the increase in hardness. As experimental data were accumulated on 14-carat gold alloys, several contradictions arose. Certain observations tended to confirm the existence of a superstructure, while other observations seemed to be inconsistent with such a transformation. PRESENT INVESTIGATION As a focal point about which to develop this subject, it is expedient to consider first

Jan 1, 1943

By Giuliana A. Zelada-Tumialan

Reduced workability and flowability of the concrete through the tremie tubes and drilled shaft reinforcement have been identified as the main causes of tremie-concrete drilled shaft concrete defects. This paper discusses two recent case studies of defective tremie-concrete drilled shafts. The defects (soft inclusions, aggregate segregation, and low concrete strength) were primarily caused by the combined effects of the tremie placing sequence, rapid concrete slump loss, and poor passing and blocking characteristics of the approved concrete mix design. The level of detail contained in the drilled shaft specifications varied between projects. However, even when the specifications incorporated several of the more recent recommendations for tremie-concrete placement, the case studies showed that typical provisions for concrete mix proportioning and placement can be further improved to minimize construction defects such as those described in this paper. Based on the findings of the case studies presented, recommendations for the development of more effective specifications are provided. The recommendations include requirements for mock-up testing of proposed concrete mix designs and evaluation of the tremie-concrete placement sequence. Performance of such testing and evaluation would greatly reduce the potential for drilled shaft defects and consequent time and financial burdens associated with them.

Jan 1, 2009

By Reno H. Sales

Our colleagues cannot in the future earn reputations and medals for achievements in milling and smelting ore and for successful management of mining companies, if some one doesn't keep finding and mining the ore to mill and smelt and to provide the basis for the good management. Good ore seems sometimes to be quite helpful to good management, and good ore is not as easy to find as it used to be. And there are still more reasons, why—when this honor had been decided upon and named for Mr. Daniel C. Jackling—it should be initially conferred on Reno H. Sales. . The terms of reference of the award are that it should be conferred upon an individual working in the fields of mining, geology, geophysics, who has made an outstanding contribution to the progress of technology in one or more of those fields. And in this initial year (the earlier years are the easiest) just that was done. I think I could get away with it amongst the old-timers of my generation if I say that this time they made the award to the individual, who made the outstanding contribution. But, as Al Smith used to say, "Let's look at the record." Really, the record is mixed up a little with extra-lateral litigation—the old-time "apex cases" under Section 2322 of the Revised Statutes. Reno Sales doesn't like such litigation, but there is little question that the urgency, generated by conflicting claims of intra-limital and extra-lateral rights, and consequent necessity for committing to records and maps the complications of Butte structure, did advance—and by several years—the first continuous, accurate, systematic, and scientific portrayal of the geological and mineralogical details of what is, after all, the most important and the most complicated copper district—at least in North America. Prior to Sales' time, some of the most eminent of geologists often waived details. One geologist took the judge to the window to show him the Rarus fault going through a notch in the Continental Divide. The entertaining testimony in the Bluebird litigation was as perfect in literary style as it was innocent of the criteria by which faulting and lack of continuity of vein structure are now recognized. At any rate, this need for an accurate record of structure was in the background—to whatever extent it was, or was not, the etiological agent—for formation of the Geological Department of the Amalgamated Copper Co. in and about the year 1900. Charles W. Goodale was at that time the head of the Boston & Montana, and John D. Ryan succeeded William Scallon as the president of Anaconda Copper Mining Co. in 1905. Horace V. Winchell, for years a specialist in extra-lateral litigation, was perhaps the man who at that date had the vision, the persuasive weight with the management, and the willingness to defend the idea of large current expenditures (as then viewed) for a complete and sys-

Jan 1, 1955

By R. J. Kendall

As we enter the new millennium, the South African mining industry has to ensure that it becomes more competitive if it is to survive in the ever more demanding global environment. Traditionally, mechanization in narrow stopes has been limited to the use of scraper winches, and numerous mechanization attempts have been restricted to pilot projects operated on an extremely limited scale (with varying degrees of success). The benefits of hydropower are well documented, and Northam Platinum has shown these benefits to be achievable on a mine-wide basis. However, the equipment originally developed for hydropower systems has followed the traditional labour-intensive approach commonly used in deep level narrow stoping operations. The problems experienced with the hydropower system are discussed and the rationale for developing alternate technologies is explored. The hydropower system has shown to be a versatile powering medium which can be harnessed for a diversity of uses. It (hydropower) enables the mining engineer to change traditional paradigms and to design an entirely new approach for optimizing the mining operation based on explosive techniques. The system developed for Northam consists of the following: ?Purpose-built stope drill rig operated off the hydropower system with special features to ensure accurate drilling patterns throughout the length of the blast hole ?Purpose-built high rate cleaning system for rapid transfer of fractured ore to the stope orepass ?Redesigned stope layout to facilitate in-stope water control and to recover fines from the run-off water ?Purpose-built drill rig for rapid establishment of reef raises and advanced strike gullies ?Purpose-built drill rig for flat end development. On both types of development end rig, emphasis is placed on ensuring accurate drilling patterns throughout the length of the hole to maximize linear advance per blast. The paper discusses the implementation of the Northam system on a large scale as well as current initiatives to further improve on the efficiencies of mining operations. It concludes by emphasizing that mechanized hydropowered stope technologies are in their infancy and thus offer unlimited scope in progressing beyond today?s paradigms to present as yet unthought of solutions for optimizing deep level ore extraction.

Jan 1, 2000

Shaft sinking through an amphibolite-granite rock mass experienced rock bursts on the shaft walls and benches. However, rock burst phenomena was exhibited only in granite, which is e1asto-brittle with ability to store strain energy caused by orogenic and man made stresses. To improve ground conditions, blasting of destressing holes at shaft corners was carried out. By this technique rock burst during shaft sinking was minimized, but not eliminated.

Jan 1, 1982

By A. D. Davis

Limestone-based material is effective for reducing arsenic concentrations below the current limit of 10 parts per billion for drinking water, typically resulting in final concentrations of about 4 to 6 ppb. However, in laboratory and field testing, further reductions to the 1 ppb range are difficult to achieve with limestone unless other material such as iron is added. The removal mechanism with untreated limestone appears to be the formation of a low-solubility precipitate of hydrated calcium arsenate, in the form of arsenate-apatite. Likely reactions and thermodynamic data indicate a theoretical removal limit of about 2 to 4 ppb for arsenic using raw limestone. Limestone also can reduce concentrations of cadmium and lead below 1 ppb in water, resulting in >99% removal efficiency. Thermodynamic constraints appear to be favorable for reactions involving the formation of otavite during cadmium removal and the formation of hydrocerussite during lead removal.

Feb 27, 2013

Detailed petrographic analyses of coal seams from the Newcastle, Illawarra, and Lithgow Coal Measures were made for a number of localities for each of twelve seams. From these analyses characteristic standardprofiles were derived for each seam. Two broad types of profile were found; one in which vitrite-poor and vitrite-rich layers alternate, and another in which there is a steady decrease in vitrite from the base to the top of the seam. From comparison of the petrographic profiles it was concluded that the Great Northern Seam in the Northern Coalfield is a possible equivalent to the BulIi in the Southern; and likewise the Fassifern to the Balgowni...

Jan 1, 1967

By D. M. Avant, S. M. Pickering

A variety of grades of very white muscovite mica are now being produced from sedimentary sands and clays in Central Georgia. The mica is naturally concentrated near the base of the lens-shaped kaolin deposits and also disseminated in associated quartz sands. The same weathering and bacterial alteration processes which have transformed the kaolins from dark organic muds to white pigment-grade industrial clays have also removed discoloring iron from the micas and developed unusually white muscovite. Further, chemical alteration has removed some potassium from the muscovite atomic structure, resulting in an easily delaminated mica which can be cleaved to unusually fine, high bulking, high aspect ratio products. The peculiar alteration history of these sedimentary micas enables production of some of the whitest, finest particle size, and thinnest aspect ratio muscovite mica products on the world market today. Raw mica feed is obtained from kaolin and sand processing by-products, and also from beneath the useful base of abandoned kaolin mines. The processed ultrafine and filler grade muscovite mica products are used for paint, plastics, cosmetics, mold release, thermal and electrical insulation, epoxy, and dry wall joint cement markets.

Jan 1, 2002

The closure of the only professional mining school in New Zealand will mean that the minerals industry will have to explore other options to fill their mining professional positions. Globally mining is not seen as an attractive career option for young people and recruitment into mining courses is at a low level. Yet industry demands ever increasing competencies with respect to technology, environmental issues and legislation. This paper addresses this issue by first discussing the attributes required of graduate mining professionals. It then looks at alternative ways on how these can be met internationally and on the home front.

Jan 1, 1997

By M. M. Botz

There are currently more that 460 mines worldwide that utilize cyanide for gold and silver extraction. Despite this large number of cyanide-related mining operations, there have been no published accounts during the previous 25 years of the death of humans due to cyanide as a direct consequence of major mining-related environmental incidents. All published accounts of human deaths due to mining-related environmental incidents have been the result of physical inundation with tailings or waste rock materials. It appears that major mining-related environmental incidents have not been concentrated in any geographic location, are likely to occur regardless of the size of the mining company and do not occur more frequently with a specific type of mining activity. Several cyanide treatment and recovery technologies have been widely demonstrated to reliably control cyanide levels in mining solutions. With proper use of these technologies, tailings cyanide concentrations can be maintained at levels protective of wildlife while reducing the potential for adverse environmental incidents. The development of an international cyanide code of practice or management plan is recommended and should take into consideration the adoption of a weak-acid-dissociable (WAD) cyanide standard that maintains the levels entering a tailings impoundment below 50 mg/L.

Jan 1, 2001

By V. G. Grechanyuk

The paper presents the mechanical properties of Cu-Mo composite materials depending on the molybdenum content. The influence of structural defects on the mechanical-physical properties of the condensates at stretching testing as well as of the lamellar grain dimensions upon the mechanical properties of Cu-Mo composite materials is also presented.

Jan 1, 2008

The Manto Verde mine is found in the coastal ranges of the Atacama desert, 1000 km north of Santiago, Chile . The deposit is a fault-breccia specularite-oxide copper mineralisation hosted by the Jurassic andesites of La Negra Formation. It is located in a tensional fault that joins twoparallel arms of the Atacama Fault. The mine is in feasibility study: reserves are of the order of 60 Mt at 0.9 wt per cent soluble copper; mining will be undertaken at a rate of 11 000 tpd utilising an open pit and the ore will be heap-leached with acidified sea water, with copper recovery and by SX/EW.

Jan 1, 1992

By D Crequer

A Peer Review Panel for the Golden Cross Mine in the upperWaitekauri Valley, Coromandel was initiated in December 1989, before mining, as a requirement of the conditions of the Mining Licence and Water Rights. The panel's function is as a technical audit and advisory team - to provide independent technical review of design, construction, and execution of mining operations, slope remediation works, and reclamation/mine closure activities. The primary role of the panel is to act in the public interest by providing assurance to regulating authorities that the design and application of on-site mining operations accords with 'good industry practice'. Panellists are not involved in design nor as advisers, although until 1997 when explicit terms of reference were written, the panellists were a sounding board for some operational proposals. The panel functions to ensure that best mining industry technical standards are met. The costs of the peer review process are met by the mining company. Review of mining operations includes environmental matters such as land rehabilitation and water quality. The focus of this paper is on the process of peer review for environmental management factors rather than for structural and mine engineering.

Jan 1, 1998

By J. Bleeck, G. Mahrt

INTRODUCTION Many excellent papers have been written and presented regarding agricultural lime and the subject has been covered extensively in books concerning soil science, fertilizing, limestone, etc. We felt challenged to construct a paper that wouldn’t merely be a repetition of past presentations. Therefore, we chose to begin with factors having the most impact on plant growth realizing that the audience is likely to be relatively unfamiliar with this subject. So, we decided to dig deep into the roots of soil and plant growth science in order to better understand the significant role of limestone in this important area. The soil with the higher plants growing upon it forms an open and dynamic ecosystem in which there is flux of energy and material (heat, light, water, nutrients, mineral and organic matter, organisms). Plants root in the soil and then take up oxygen for root respiration, yielding energy for nutrient uptake, water for turgescence and transpiration and use in photosynthesis and the mineral nutrients needed for the synthesis of organic matter. Above the ground the plant takes in light energy and heat using them in photosynthesis to assimilate atmospheric CO2. Photosynthesis is the basic life process of creation. However, we will look at the root room where soil, water, air, and heat economy and the supply of nutrients determine soil fertility and the important role lime plays here. Location is the primary point to be considered when discussing agriculture (climate and soil); secondly, the dynamic and mobility of the minerals (plant nutrients) in the soil; and thirdly the conversion of organic substances into humus. And then there is a great deal of water involved in the growing process. In order to produce 1 kg of dry plant substance, 300 to 800 kg of water must be pumped through the plant and is then lost by transpiration. Cereals, vegetables, and sugar beets consume between 400 to 500 kg of water during the growing process and long-growing crops, such as alfalfa and clover, can consume 600 to 800 kg of water per kg of finished product. Without water, a plant cannot grow. (Reference 1)

Jan 1, 2006

By V. Bondarenko

The forecasting of floating earth inrush into the working is to a great extent connected with the investigation of the rock mass stressed-deformed state around the working. The aim of such investigations is to estimate the carrier ability of the protective layer (which is stabilized by the physico-chemical mode of fixing) and to determine it's thickness, which is to be sufficient to present the floating earth inrush into the working. We consider the protective layer to have exhausted it's carrier ability if the rocks of this layer reached the overlimit phase of deformation and it's greater part (section), which adjoins the working. is destroyed up to the limit of the remaining strength. So, the aim of investigations is to determine the size of the rocks inelastic deformation zone in the roof of the working. It is necessary to take into account the presence of water saturated seam in the roof and the overlimit characteristics of the rocks, their ability to lower the carrier capacity up to the level of the remaining strength.

Jan 1, 1996