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By Takashi Fujii

In the OG (Osaka Gas) process which includes a fusion process of sewage disposal sludge in coke bed knowledge of molten and fluid properties of the sludge are most important to controll the process in good condition. Thus, the softening and melting temperatures and viscosity were measured by the sessile drop technique and a rotating viscometer. Obtained results are summarized as follows: Melting character of sludge slag is varied according to their composition, but closely related to CaO/SiO2 ratio in ordinary sludge and to CaO/(Cr2O3,+Al2O3+P2O5) ratio in Cr2O3 containing sludge. Fluid property of sludge slag has a correlation with optical basicity or Riboud parameter, However, the correlation is poorer than that of metallurgical slags. Especially, chromium oxide containing sludge shows high viscosity and behaves somewhat different manner from ordinary sludge.

Jan 1, 1992

By D. L. Price

This paper presents a method of measuring field power consumption of shearers and deriving specific energy consumption versus shearer haulage speed performance curves. A description of a computer program which simulates the cutting action of a shearer drum is presented. A comparison between the field specific energy curves and the computer simulation results is made. The simulation results compare well with the field data where all the coal seam is being cut by the shearer. The computer simulation results give hack-calculated field pick force cutting characteristics, which allow the performance of the shearer to be predicted for other operating conditions, e.g. effect of changes to pick lacing, effect of changing the drum rotational speed, allows the calculation of power requirements for a particular production rate.

Jan 1, 1992

By G. M. L. Robinson

Mineral Processing Wastes, as defined by the Environmental Protection Agency (EPA), has determined that most of the mine wastes will be regulated pursuant to subtitle D (Solid Waste Regulations) of the Solid Waste Disposal Act while specific mine waste categories will be regulated within the framework of the Toxic Substance Control Act. Though EPA's determination currently relieves the industry of the regulatory constraints mandated by the Resource Conservation and Recovery Act (Hazardous Waste Regulations) Subtitle C regulatory framework; the industry is not granted immunity from historical or current environmental regulations related to listed or characteristically hazardous or solid wastes. Because of the current regulatory trends and the need to implement cost effective remediation alternatives; advanced currently available on-site remediation technologies are available to minimize, reduce, contain or prevent environmental impacts related to mining and processing activities. In light of industry technical needs, an overview of the research and commercially available remediation technologies will be discussed and a brief discussion of the strengths and weakness of each technology will be presented. Technologies to be discussed includes stabilization, solidification, soil wash, soil flush, thermal distillation, pump and treat, metal extraction, centrifuges, filter presses, bioremediation, and incineration.

Jan 1, 1992

The coal-bearing regions of Colorado cover approximately 29,600 square miles, which is 28.4 percent of the state's total area. The most important coal-bearing regions are located in the north western and west-central parts of Colorado. Coal resources vary from lignite to anthracite. More than 70 percent are bituminous; 23 percent subbituminous; 5 percent lignite; and less than 1 percent anthracite. The state's coal reserves total about 17.2 billion tons, 3.5 percent of national reserves. Approximately 8.8 million acres of coal rights in the state are owned by the Federal Government; on about 72percent of this land, the Federal Government controls both the coal and the surface rights. It is estimated that approximately 4.2 billion tons of coal reserves are under federal ownership in Colorado. Permitted acreage of mines in Colorado ranges from 40 to 13,114 acres. Differences in elevation create many climatic zones in Colorado. Local annual precipitation can average less than eight inches in some areas in extreme western Colorado to more than 30 inches in certain mountainous areas. Generally, precipitation rates are low at most mine sites, making revegetation difficult. Colorado gained primacy when its regulatory program was conditionally approved December 15,1980. The Abandoned Mine Land Program was approved June 11, 1982.

Jan 1, 1992

By Carl C. Nesbitt

A study was conducted to investigate the claims of early observers who noted an increase in the rate of gold dissolution when chlorine was chemically produced in the leach vessel compared to sparging with chlorine gas. This "nascent" chlorine was presumed to be an active intermediate in the production of chlorine (C1,l from chloride ions. The study used UV light to produce an activated chlorine atom intended to recreate the observed increase in the gold dissolution rate. Although no change in the kinetic rate was observed, the reaction mechanism by which chlorine reacts with particulate gold was instead determined. Various concentrations of multivalent cationic chloride salts were added to the leach solution to demonstrate that the increased dissolution rate was due to the increased concentration of the chloride ion and ionic strength of the solution.

Jan 1, 1992

By Fraser C. J

The township of Yalloum was established in 1921 to provide accommodation for the work force on the sites of the power station and open cut which were to become the basis of Victoria's electricity industry.A company town, Yallourn flourished, and in its heyday in the 1950s the township had a population in excess of 5500 residents.However the town was sited over a valuable coal field. In the 1960s, studies conducted by the State Electricity Commission indicated that excavation of this coal as a continuing development of Yalloum Open Cut was the optimum choice to meet the growing energy needs of Victoria. Operation in what became known as the Township Field commenced in 1979 and the completion of the overburden stripping was successfully achieved on target in 1991.

Jan 1, 1992

By King R. L

Low-enthalpy geothermal groundwater resources occur at relatively shallow depths in the Upper Cretaceous/1'ertiary sedimentary sequence in the on-shore Gippsland Basin. The main stratigraphic unit containing hot groundwater is the Latrobe Group. Groundwater temperatures in the range 30 to 70¦C have been recorded from depths between 500 and 1000 m. The hottest groundwater is in the Latrobe Valley and Lake Wellington depressions. Geothermal gradients in these areas range from less than 2¦C/100 m to over 10¦C/100 m (compared to a world average of about 3¦C/100 m). A number of theories have been advanced to explain the geothermal anomalies including exothermic reaction such as oxidation of coal, mixing with deeper, hotter groundwater and high geothermal fluxes along fault zones. Variations in geothermal gradients can also result from type and thickness (and hence thermal conductivities) of the sedimentary pile, depth to consolidated basement rocks, and influence of groundwater flow patterns including proximity to recharge zones. The hot groundwater in the Gippsland Basin has substantial potential as a source of energy for direct heat applications such as process heating, space and water heating for buildings, and agricultural and aquaculture. Geothermal energy has a number of environmental advantages over traditional sources of energy. It is clean, safe, causes minimal land disturbances and in most cases is naturally renewable.

Jan 1, 1992

By J. S. Jaspal

Mining of thin coal seams is both difficult and uneconomical. As a result, most of thin-seam coal reserves in the U. S. are not being mined. It is estimated that nearly 910 Gt (K. Unrug, 1985) of coal reserves exist in 355 to 710 mm thick seams. The Bureau is attempting to develop new techniques for mining 150 to 1065 mm thick coal seams. This paper summarizes the research work on existing thin-seam mining techniques, testing on small and full scale physical models of the Bureau slot mining concept, and computer modeling of the full-scale process.

Jan 1, 1992

By J. D. Ecuyer, L&apos

he microstructure of galvanneal coatings formed on extra low carbon and interstitial free steel substrates has been characterized using electron microscopy (TEM and SEM) and x-ray diffraction. The coatings are found to consist of a mixture of gamma, delta and zeta phases, of which delta is the main constituent. The amounts of each phase influences the powdering resistance of the coating which was evaluated using reverse Olsen testing and 60" bending. For the three heat input conditions considered, IF coatings were always found to contain a significant amount of gamma and only those which retained zeta phase on the surface exhibited a satisfactory powdering resistance. In much the same way, ELC coatings with relatively thick gamma layers performed satisfactorily only when some zeta was retained. It was also found, however, that coatings with minimal zeta and gamma had an excellent powdering resistance. The latter coatings were produced under galvannealing conditions of lower relative heat input. These results indicate that in addition to the zinc bath composition, coating weight and galvanneal thermal cycle, the base steel chemistry also has an effect on the coating microstructure. Knowledge and control of all aspects of galvannealing is therefore essential to consistently produce acceptable coatings.

Jan 1, 1992

This paper outlines the aims, objectives and means by which a life of mine land use plan was established for Comalco's bauxite mine at Weipa. Comalco realises the need to strategically plan for future mining activities and still minimise the impact of operations on the natural resources of the region. With this realisation long-term forward planning has been implemented to improve the Company's ability to select future sites for mining, industrial use, agriculture, town expansion and conservation purposes.The knowledge of mineral, water, soil and animal resources has expanded dramatically in the past decade. During 1990 Cornalco purchased Geographic Information System technology which has allowed previously collected resource data to be presented in map form. These maps as part of the Life of Mine Land Use Plan are both information based and strategic which can be efficiently updated. The maps allow a broad audience from engineers, geologists, environmental scientists and site managers to government officers and the general public to comprehensively view and scrutinise the operations.

Jan 1, 1992

The theme of this conference is æRediscover OtagoÆ and the conference occurs during a resurgence of economic activity in New Zealand, and in particular at a time when the Macraes Gold Project has had a significant effect on mining and business activity in Otago. The Macraes Gold Mine has implemented a Zero Accident Programme and this paper reviews some of the factors responsible for the implementation.

Jan 1, 1992

By Bin Du

In recent years, concurrent product design and process is gaining popularity and will become a norm of the industry of the future. Forging has been a critical manufacturing process for production of components with superior tensile strength, toughness and grain flow. This paper describes an expen system which is being developed for forging die design and forging process analysis in concurrent engineering environment. Rules and guidelines pertaining to forgeability are formulated and incorporated into the knowledge-base in building the system. The system is built using an object-oriented paradigm. The object-oriented approach and hierarchical rule structure paradigm are briefly discussed. Finite element analysis packages (ALPID-2D) were incorporated into the program to give the simulation result of the forging process. The system can automatically produce a competent design and recommend a set of processing parameters for a given product. The designer can modify the design according to the result of the simulation.

Jan 1, 1992

By D. A. Knight

The property is located in the Porgera Valley 600 Km North West of Port Moresby. The remote location is 2500 m above sea level. The mine area has 3,600 mm of annual rainfall and a temperate climate with temperatures ranging from 10" C to 22° C throughout the year. Alluvial gold was reported in the Porgera area in 1938 and has been an important source of revenue for the area for many years. Intermittent exploration was carried out until the 1960's when Placer (PNG) Pty. Ltd. with Mt. Isa Mines commenced an extensive exploration program. The property was brought to production in 1990 by the Porgera Joint Venture group consisting of Mount Isa Mines Ltd, Rennison Goldfield Consolidated Ltd. and Placer Dome Inc, each with a 30% ownership and the Government of Papua New Guinea with a 10% share. Placer Dome Inc. is the manager of the property with construction under the direction of the Placer Dome Technical Services group.

Jan 1, 1992

Oaky Creek Coal (OCC) has embarked on an ambitious program to fast track the introduction of Trench Mining into its current mining operations. The project has the capacity to allow the extraction of reserves at stripping ratios, uneconomical by conventional mining methods.Trench mining using Continuous Highwall Mining (CHM) technology reduces the in-situ stripping ratio to 4:3; compared with a stripping ratio of 20:1 using conventional mining techniques.

Jan 1, 1992

By Mortimer J. Richardson

Dredging can be traced to early times where it may have been derived by the Phoenicians prior to the 4th century B.C. The first tangible design drawings of a bucket ladder (BL) dredge can be found in the collections of Leonardo da Vinci (1452-1519), which he produced when he was attempting to create better methods of channel and port dredging. The perfection of the system did not commence until after the invention of the steam engine in the early 1800's; providing the impetus to progress from man-powered mud mills, horse drawn along polders or dikes in the Netherlands, England, France and Germany, to steam-driven. In the 1860's following the various gold rushes in the U.S., Australia, New Zealand, Siberia and South America, with placers in particular, efforts were begun to apply mechanization to achieve deeper digging. There is a recording of a dredge being installed to mine gold in Montana in the 1860's but did not include a processing system. Then in the 1880's in New Zealand, some practical engineers developed a system that is said to be the first bucket ladder mining (BL/M) dredge for mining gold placers. In studies of the New Zealand gold dredging experience, it is estimated that some 500 dredges were built to mine gold between the 1880's and 1942. A careful analysis of the data, however, shows that very few were profitable. The technology appeared to stagnate in the early part of the century. Two of the BL/M dredge design engineers left New

Jan 1, 1992

By Sean Gallagher, Thomas G. Bobick, Richard L. Unger

This paper describes research by the Bureau of Mines on alternative materials-handling strategies for reducing the costs and incidence of back injuries in low-seam coal mines. Strategies recommended for redesigning materials-handling tasks include elimination of tasks, mechanization of tasks, and matching lifting tasks to the physical capabilities of underground miners. The report also discusses other methods that can be used by management to reduce the costs associated with back injuries. More detail can be found in Bureau of Mines Information Circular 9235 (Gallagher et al. 1990).

Jan 1, 1992

By A. G. Pasamehmetoglu

This paper describes the conver¬gence and load measurements carried out in inclined seams at five longwall faces, two of which were supported by hydraulic props and the other three by conventional timber supports in Karadon-Gelik mine. The minimum support capacities determined in this study are compared with the results obtained from two empirical approaches suggested by Wilson (1975) and Jacobi (1981). The characteristics of hydraulic props to be used and support patterns in the longwalls are found, conclu¬sions are drawn and suggestions are made. Design nomograms are prepared for field engineers, in order to be able to approach the problem more confidently and realistically.

Jan 1, 1992

By Michael D. Balen

During the years 1987 through 1989, the Bureau of Mines Alaska Field Operations Center (Bureau) in cooperation with the Western Field Operations Center and the Alaska Division of Geological and Geophysical Surveys (ADGGS), conducted mining, geological, and geochemical investigations in the 5.7 million-acre Valdez Creek Mining District (VCMD). This investigation was conducted as part of the Bureau's continuing Mineral Land Assessment (MLA) mining district studies program. The Bureau's MLA program is designed to provide reliable and comprehensive mineral resource information that supports mineral resource policy and land use decisions made by Congress and Federal land management agencies. The information also provides the basis for decisions that would expand the domestic supply of important mineral resources, primarily strategic and critical minerals. Much of the MLA work is done jointly with cooperating State or U.S. geological surveys.

Jan 1, 1992

By P. E. Damon

An arsenal of isotopic techniques is avail-able that can date the full range of hydrothermal ore deposits. The following are prerequisites for ideal results: (1) Careful collection of samples that are related to the event in a field and process context; (2) Optical examination of the component selected for dating to be sure that it has not been altered; (3) Careful preparation of a pure component of the sample selected for dating; (4) Precise and accurate measurement; (5) Knowledgeable interpretation of the data with reference to decay systematics, properties of the component analyzed as well as the field context and thermochemical environment of the ore process.

Jan 1, 1992

By T. N. Moore, E. M. De Souza

J. Dasher Regarding the March 1991 ME technical paper by De Souza and Moore: For more than a decade since my February 1981 article on how to use modern metric, which SME-AIME had decided to do, I have monthly pointed out metric errors to the editors. In part, I do this because there has been no action to allow editors to fix figures and tables or to allow them to require authors to do so. The latest resulting atrocity provokes this discussion of vibrating drill handle units being stated in decibels. Reply by T. Moore We have read the discussion of our paper by Mr. Dasher. Our reaction is one of surprise and incredulity. It would seem that Mr. Dasher takes exception to the use of the decibel scale to present vibration acceleration data, and the use of hertz as the unit for frequency. The basis for his objection to the decibel appears to be that it has no dimensions (which somehow invalidates its use), that it is "non-metric" and, finally, that it is parochial (of limited or narrow scope). His objection to the use of the term hertz is not stated, but we will assume that it stands condemned as "non-metric" and parochial. Obviously we disagree with Mr. Dasher's views and will now outline our reasons. Although the decibel scale originates from transmission line theory and telephone engineering, it is also at present widely used, not only in the fields of electronic engineering and acoustics, but also in the area of vibration. The original definition of the decibel (dB) was based on power ratios: dB = 10 log 10(W/W0) where Wo is a reference power. However, as the power measured across a given impedance is related to the square of the force acting upon this impedance, Z, a more commonly used definition is: [2 dB = 10 logF /Z) = 20 log F/F 10\ F0 2 /Z(0)] where F and F0 are the r.m.s. values of the forces. Now, if the measurements are related to one and the same impedance, the decibel notation in the form of 20log10(X/Xo) may be used as a convenient relative magnitude scale for a variety of quantities. Thus, X may, for instance, be an r.m.s. displacement, velocity or acceleration. It is only required that XD always be a reference quantity of the same type as X. That is, when X represents an acceleration, then X0 represents a reference acceleration. This is the formulation used in our paper. This was not an arbitrary choice on our behalf but reflects standard practice as specified in the International Standard ISO 5349-1986(E) Mechanical Vibration - Guidelines for the Measurement and the Assessment of Human Despite the metric prefix, the decibel is a parochial expression of (l) the logarithmic ratio of the loudness of a sound to what is normally audible or (2) the logarithmic ratio of two power signals in radio or electronics. A decibel is not a unit, much less an SI, unit and has nothing whatsoever to do with the acceleration of drill handles. Stating that m/s2 (acceleration) is decibels is without reason. Whoever reviewed this material should not have allowed publication of figures of dB and H.[ ] Exposure to Hand-Transmitted Vibration. This was clearly stated in the "measurement protocol" section of our paper. This quantity is then referred to as the acceleration level and is expressed in dB. We may have inadvertently caused some confusion when we simply used the term acceleration to refer to acceleration level on our diagrams. At the time, we felt the use of dB or m/s2 would make the context clear to the reader. For any confusion this decision may have engendered, we apologize. Since the decibel expresses the ratio of two like quantities, it certainly has no dimensions. It is, however, common practice to treat "decibel" as a unit as, for example, in the sentence, "The acceleration level measured at the operator's hand was 160 dB." The expression of measured quantities in dimensionless form is not inherently unacceptable. In fact, in many areas of engineering it is standard practice (consider the use of Reynolds Number, Nusselt Number, etc.). The fact that the decibel is a dimensionless quantity makes the question of whether it is a SI unit nonsensical. However, it is valid to insist that the dimensional quantities used to obtain the decibel values be expressed in SI units. A careful reading of our paper will make it clear that the measured acceleration was, in fact, expressed in units of m/s2 as was the reference acceleration (l x 10-6 m/S2). These are the accepted derived SI units for acceleration. See, for example, the standard ASTM E380-89a Standard Practice for Use of the International System of Units (SI) (The Modernized Metric System). Concerning Mr. Dasher's implication that hertz (Hz) is an unacceptable unit of measure for frequency, we would again refer him to the standard ASTM E380-89a. Here, he will find (section 2.4.2) that hertz is an accepted "special name" for the derived SI units-1. This is in keeping with numerous other international standards including ISO 5349-1986(E) to which we referred in our paper. In conclusion, we agree with Mr. Dasher on the desirability of expressing measurements in modern SI units. But we would remind him that the standards that define the use of these units, and the accepted means of presenting measured data, are in a continual state of refinement. It is, therefore, incumbent upon him to keep abreast of these changes if he wishes to constructively critique the work of others.[ ]

Jan 1, 1992