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Based on the idea to copy crystallisation and precipitation phenomena occurring in nature, a new technology was developed allowing the preparation of metastable, mineral forming solutions. If these solutions are brought into soil or rock formations, directed precipitation of slightly soluble minerals takes place. Immobilisation of dissolved heavy metals as well as overlaying of reactive mineral surfaces with insoluble minerals can be achieved. It is possible to prepare solutions leading to the formation of gypsum, BaSO4, CaCO3, Ca(OH)2, Al(OH)3 or Fe(OH)3. The successful large-scale application of BaSO4 forming solutions was demonstrated in the former uranium mine Koenigstein of Wismut GmbH, (Germany).

Jan 1, 2003

The Mining Enforcement and Safety Administration has called attention to the increasing frequency of accidents occurring during mine maintenance and repair tasks in a recent publication. Data from the agency's Health and Safety Analysis Center have been compiled and presented in a report titled "Analysis of Injuries Associated with Maintenance and Repair in Metal and Nonmetal Mines,"* a booklet aimed at answering four questions: (1) Which pieces of operating equipment are most frequently involved in maintenance accidents; (2) Which maintenance functions are the most hazardous; (3) Which tools are most often associated with injuries; and (4) What is the comparative hazard of welding or flame cutting vs. mechanical or electrical maintenance functions.

Jan 3, 1978

By G. J. Koons, J. L. Uhrie

Field density studies carried out at the Phelps Dodge Chino Mine have found that truck-induced compaction is limited to the upper 2.4 m (8 ft) of an individual lift. Hydraulic properties of material compacted to field densities were determined in a laboratory setting. Saturated flow models were then run, simulating the effect of compacted zones within a stockpile. Modeling shows that compaction can prevent solution flow through large portions of the stockpile. This implies that care must be taken to ensure that ripping is carried out to a depth of at least 2.4 m (8 ft) across the entire stockpile to achieve uniform solution flow. Uniform solution flow will result in maximum leach recovery.

Jan 1, 2002

By D. Zaharaki

In the present experimental study the geochemical stability of inorganic polymers was studied by immersing them in various solutions (distilled water, seawater and 0.5N HCl) for a period of 7 months. Inorganic polymers were synthesised by mixing ferronickel slag with kaolinite, potassium hydroxide and sodium silicate solution. The cement like paste was heated at 80 °C for 48 hours and left for curing at room temperature. Their structural integrity was assessed by compressive strength testing after subjection to freeze-thaw cycles as well as high temperature heating. XRD studies were carried out in order to identify new formed phases and provide useful information regarding the progress of the mechanisms involved.

Jan 1, 2008

By John J. Ridgeway

Habits take us where we were yesterday and attitudes tend to keep us there. Until recently, little had been accomplished to improve conventional explosive energy for use offshore. But with the special requirements of the Offshore Oil Industry, and particularly in the North Sea, most equipment, products and services must be specialized as well. Previous attempts to excavate a trench for a sealine in surf areas had been impossible to accomplish. But with the application of safe, controlled explosive energy, an impossible task to accomplish yesterday has now become a reality. Explosive energy, often overlooked as a convenient and economical offshore tool, excavated a clean trench underwater for a 40" sealine at Djeno in the African Congo recently.

Jan 1, 1977

By V. C. Pandolfelli, S. F. Santos, L. A. Rodrigues

Under conditions of stable crack propagation at room temperature, the elastic energy stored in ceramic materials is converted mainly to surface energy. However, at high temperatures, creep may also occur in such materials, in which case it will present a ductile behavior. This paper discusses the brittle-ductile transition of a refractory material. Stable crack propagation and creep tests were carried out under a three-point bending device. A commercial ceramic containing 63 wt-% of SiO2 and 31 wt-% of Al2O3 was used as testing material. The results revealed that the change in behavior from brittle to ductile was caused by softening of a vitreous phase present in the material's microstructure.

Jan 1, 2004

By Robert C. Peddicord

Application of Quality Management philosophies and techniques commonly referred to as Managing for Continuous Improvement, Team Management , or Managing for Consistency is required in today's mining, manufacturing, and service industries in order to meet quality demands, beat competition, lower costs, optimize operations, effectively use personnel, improve morale, and enhance profitability. Most of these phiosophies and techniques are known to today's managers but either have fallen into disuse or were never allowed to surface in the corporate environment of the organization. Managers should review and adopt the philosophies and techniques of Quality Management and use them to revitalize their organizations and bring about a "paradigm" shift in the way we manage, thereby achieving the goals listed above.

Jan 1, 1991

By Henry R. Tiedemann, William H. Hansmire, Harvey W. Parker

Although the use of precast concrete segments for tunnel linings has been common for many years in Europe, acceptance of this type of lining has been slow in the United States. This paper explores the cost, design, and construction considerations of concrete segmental lining with a view to promoting its use in this country when favorable conditions exist. The different perspectives held by owners, designers, and contractors are discussed. In addition to cost, other considerations include previous design and construction experience, size, length and function of tunnel, watertightness, and liability. Cost comparisons are made to traditional ground support and lining. Under favorable conditions, the use of precast concrete segmental linings can be technically feasible and cost effective.

Jan 1, 1987

POSITIONS VACANT The National Bureau of Standards needs men to fill metallurgical positions with salaries varying from $1200 to $2000, depending upon the training and experience of the candidate. Experience either in ferrous. or, non-ferrous metallurgy. Duties will be almost entirely of an investigational nature, in connection with problems of military importance. Qualified men are urged to send to the Bureau of Standards at once a statement of training and experience, names of references, acid minimum salary that would be accepted, so that they may he advised of appropriate civil service examination for which to file papers. Until further notice, such papers are received by the Civil Service Commission at any time and ratted promptly.

Jan 10, 1917

By Gregory P. Lorsbach

Significant information about any blast is contained within the seismic signal generated by the blast. In this study, standard digital signal processing techniques are utilized to extract source parameter information from a seismic signal recorded at distances commonly used in compliance monitoring. Specifically, digital seismic data was analyzed using the cross-correladon and autocorrelation functions for the purpose of determining delay timing. The initial results are interpreted to indicate that: 1) Individual delays can be identified analytically but not visually for short delay periods and large source to receiver distances, 2) Delay timing can be resolved to a few milliseconds, and 3) Results can be obtained from data collected at a minimal number of locations.

Jan 1, 1991

By Randall D. Peterson

Economic operation of a mine ventilation system must include some means by which operating costs can be quantified and evaluated periodically. Current practice at most mines relies upon the best judgement of foremen, engineers and managers to identify high cost or problem areas in the system and to estimate potential costs and benefits of work proposed to reduce inefficiencies. The problem with this is that significant savings can be overlooked or sub-economic projects may be undertaken when sufficient attention is not paid to the interrelationship between airflow characteristics and corporate financial criteria. In order to accurately determine costs and benefits it is necessary to view the solution of each potential ventilation problem as a separate economic opportunity.

Jan 1, 1993

By Kellett KR

Gold Mining at the Lancefield Mine was commenced initially in 1897 and continued intermittently through to 1956 when rising costs and mine cave-in forced closure. The mine was redeveloped in 1981 and a new-oxide treatment plant commissioned, followed by a new refractory treatment plant in late 1982. Both these treatment plants are located within the Windarra Nickel Project plant area.The refractory ore is processed by fluidised bed roasting of flotation concentrates. This is carried out in two series connected reactors to maximise arsenic and sulphur eliminations and to minimise reagent consumption. For gold recovery the zinc precipitation process was initially used, to be later replaced by carbon-in-pulp.

Jan 1, 1984

By Jones

Extractive metallurgy in the mining industry in Western Australia has diversified and increased in the last 11 years. Before 1980, the industry mainly produced alumina, nickel, mineral sands and iron ore, with the gold industry restricted to five operating plants using Merrill-Crowe technology. In 1981 Carbon-in-pulp (C]P) plants were commissioned at Kambalda, Kalgoorlie and Meekatharra.Currently, the gold industry has some seventy CIP plants in operation, production of synthetic rutile has increased tenfold to 500 000 tpa, alumina production has doubled and production of copper, lead and zinc concentrates has begun. Other extractive metallurgy plants recover tin, niobium and tantalum, silicon, titanium dioxide and zirconia. Current proposals include vanadium, steel and rare earths.

Jan 1, 1992

By Elburt F. Osborn

The phrase "Clean Synthetic Fluid Fuels From Coal," implies that it is possible to obtain adequate and dependable supplies of fuel without sacrificing the quality of our air, water, and land. Because of the long lead times needed to develop technical feasibility, into commercial reality, however, vigorous efforts must be made now in order to do it. The available options for clean fuels include many exotic sources, like solar and geothermal power, fuel cells, and thermionic and thermoelectric systems. To solve the energy crisis, however, we have three basic energy criteria-abundance, reliability, and commercial availability by 1985. Only processes based on converting coal and oil shale to clean, synthetic fluid fuels can meet all three.

Jan 9, 1974

By Lawrence M. Lenahan

Cleveland's Southwest Interceptor Contracts No. 3 and No. 4 are continuations of Contract No. 1 addressed at the 1987 RETC with geology, equipment, and methods that differ greatly. The two contracts consist of 791 m (4.22 miles) of 3.5 m (11.5 ft) tunnel lined to 2.9 m (9.5 ft), nine access shafts, six drop shafts, and six collection structures. The excavation drive was completed by the use of a 1970 vintage Robbins TBM hybrid for this particular job through the use of both new and old technology. All other excavations were successfully accomplished through drill and blast method in tight residential areas. Concrete lining and connections were completed nine months after holing through.

Jan 1, 1989

By Prisbrey K., N. Choi, A. Burbank

Large tonnages of low grade refractory gold ores are not presently being treated because they resist direct cyanide heap leaching and because they are too low in grade for more expensive oxidizing pre-treatments. If they could be oxidized while remaining in heaps, they could be economically leached with cyanide. The solution is to use bacteria to partially oxidize the encapsulating pyrite mineral which allows cyanide dissolution of the gold in a separate treatment. A variety of refractory ores from different locations was crushed to minus three quarters inch, loaded into columns, and inoculated with T. ferrooxidans. The bacteria attacked the pyrite causing biooxidation, and gold recovery increased 30 to 120 percent after three months curing.

Jan 1, 1990

Modern off-highway trucks have evolved over 30 years from small 20 ton units to vehic- les with capacities of up to 170 tons. Diesel engines are used by all manufacturers while transmissions are either mechanical or electri- cal. Development over the years has kept pace with component availability from engine, trans- mission and tyre manufacturers.Computer simula- tion studies are recognised for purposes of vehicle evaluation and costing under various op- erating conditions. Several manufacturers are currently manufacturing or evaluating vehicles with capacities of up to 260 tons. This paper describes the essential facts associated with the operation of off-highway trucks of the rear dump type in the mining industry.

Jan 1, 1973

By Albinson T

Mexican epithermal deposits can be broadly grouped into two types based on their contained metals, distribution, associated igneous rocks and fluid inclusion compositions. Silver-gold deposits (e.g. Tayoltita) mostly occur in the western part of northern Mexico where host rocks consist of Eocene, intermediate composition volcanic and intrusive rocks; fluid inclusion studies indicate that mineralizing fluids were _10 eq. wt. % NaCl). The distribution of these two deposit types, crosscutting major major crustal sutures, and the close spatial-temporal relationships between mineralization and magmatism, together suggest that magmatic processes were more important in the formation of mineralizing solutions, as a source of both ligands and metals, than the segments of crust hosting deposits.

Jan 1, 1995

By John T. Crawford

Various open pit limit-analysis techniques have been utilized for many years to design pit limit surfaces. In the last 15 years there have been many advances in developing sophisticated computer methods to aid this process. The extensive capability of the digital computer has led to effective utilization of multiple alternative approaches to problem solving. Computerized open pit limit analysis methods can be applied to a broad scope of long range and intermediate range mine planning and design needs. This paper provides an overview of some of the more important of these applications. While not covered in detail, they are meant to indicate the flexibility and adaptability of open pit limit analysis methods and to stimulate thought.

Jan 1, 1979

By Don U. Deere

The tunnel boring machine (TBM) can be a magnificent tunneling device under optimal rock conditions. Such ideal conditions would include good Rock Material Characteristics (compact, uniform; low to medium strength, hardness, and abrasiveness); good Rock Mass Characteristics (few joints and shears; unweathered); and good Geologic Environmental Characteristics (above groundwater level and moderate in-situ stress). Such idealized rock conditions would eliminate support problems, fallout at face and grippers, frequent cutter changes, and water problems. Daily advance rates of 50 m would be commonplace. Unfortunately, nature seldom provides the ideal geologic characteristics. The challenge to the geologist, machine manufacturer, and contractor is to provide equipment and procedures to best handle the adverse geologic features, once identified.

Jan 1, 1981