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By James A. Sommers

Combustion of niobium nitride powder in a stream of oxygen results in several niobium oxide phases, depending upon reaction parameters. Under rapid oxygen flow, the oxidation produces a molten mass which coalesces into droplets of ca. 2 mm dimension and effectively quenches to leave NbO2 and other lower oxides of niobium, despite the ambient atmosphere of oxygen. A preliminary survey of reaction parameters which govern the split between reduced and oxidized products is presented. This technique offers novel synthesis means for binary oxides when mixtures of NbN and other materials are combusted together, since the niobium moiety is generated in a molten state.

Jan 1, 1995

By Tatsuo Itou

Both sales volume of Aluminum Can and its recycling rate are remarkably increasing here in Japan. In 1993, recycled can volume was 11.78 billion cans ( 116,258 metric tons ) and its recycling rate 57.8 percent. We, MITSUBISHI MATERIALS CORPORATION. the leading manufacturer of aluminum can in Japan and our affiliated companies are very deeply involved in recycling used beverage cans ( U.B.C ) and recycling them back to can stock. In this paper. I would like to present the following; 1. Recent trend of beverage can consumption in Japan. 2. Trend of aluminum can and its recycling rate in Japan. 3. Future of aluminum can business in Japan.

Jan 1, 1995

By Robert S. Setren, Jeffrey L. Ambs

The disposable diesel exhaust filter (DDEF) system developed by the U.S. Bureau of Mines and Industry cooperators for heavy-duty permissible, diesel-powered haulage vehicles, effectively reduces in-mine diesel particulate matter concentrations up to 95%. However, there are concerns about the hazards that exist when the filter is used in situations for which it was not designed. This work investigates the exhaust gas temperature limits to which the filter elements can be exposed without posing a safety or health hazard, such as 6re or off-gassing toxic compounds. A filter approved by the Mine Safety and Health administration and after-market filters were evaluated under varying engine exhaust conditions to determine if after-market filters pose an unacceptable hazard when used in a DDEF system. Filters were laboratory tested at engine exhaust temperatures ranging from 77°C to 290°C. Of the seven filter types tested, six appeared suitable for use on water scrubber-based cooling systems and two appeared suitable for use on dry heat exchanger type exhaust cooling systems with exhaust temperatures up to 150°C. Any filter elements used as exhaust filters on permissible diesel machines must be approved by MSHA for that application. Mine operators who wish to use an after-market filter element should request an MSHA field modification. MSHA will work with the mine and filter manufacturer to ensure its use in this exhaust system application does not pose a health or safety hazard.

Jan 1, 1995

Constraints on the mineral industry are best treated as issues that have to be understood and managed in partnership rather than in conflict with communities. TheZapopan development at Mt Todd in Australia and the Martha Hill development at Waihi in New Zealand are but two of many recent successful examples at the local level.   However, at the national level, the issues are more complex and more difficult to resolve because the most influential stakeholders are now the urban electorates and governments defer to their perceptions when making decisions and policy. In the developed countries, government policies for the development of mineral resources have been progressively eroded since the early 1970s. At the same time policies for the environment and for native land rights have generally been carried out in a way that has reduced access to minerals and increased the cost and risks for prospectors and developers (Hancock, 1995). Since the end of the Cold War, the lesser developed countries (LDCs) have introduced policies to attract investment in their mineral resources that remained undeveloped under previous unstable or hostile regimes. The increased attraction of these LDCs and the decreased attraction of the developed countries has caused many Australian and North American companies to outlay increasing proportions of their budgets and capital investment in the LDCs.   Significantly, LDC policies for environment protection do not discourage exploration and mine development, Surveys of the relative appeal of the LDCs and the traditional mining countries of the developed world, rate Chile, Argentina and Indonesia ahead of Australia and Canada in terms of risk, delays and ease of doing business (Australian Mining Monthly, February 1994).

Jan 1, 1995

By Luis W. Pommier

Large quantities of sea sludge containing halogenated organic compounds, such as PCB, oils and metals like arsenic and lead have accumulated throughout the years at the bottom of sea channels and harbors and are obstructing navigation and creating environmental problems which need to be resolved. A sludge from a California port would be dredged by suction pumps, it would be processed in a plant which would be built either on firm soil or on floating platforms. The sludge shows contents of up to 1 ppm of PCB, 15 % oil and 10 ppm of arsenic, which generates a very fetid odor. Bench scale work indicates that most of the contamination concentrates on the solid phase, in fact, only minor amounts of oil report to the sea water and can be readily removed by physical means. After separation of the sea water from the solids of the sludge by decantation, it is possible to solubilize the PCB, the oil and the metals into an organic solvent leaving a non-hazardous soil for disposal near the harbor. The PCB is dehalogenated during the solubilization process leaving a liquor solution containing the oil and metals. The oil is extracted leaving an aqueous solution containing the arsenic. Further process extracts the arsenic from this solution rendering the liquid non-hazardous. Transportation and disposal of the sludge is impractical. There are hundreds of thousands of tons of hazardous soils accumulated in each harbor, which would fill the hazardous waste disposal sites available and it would be, prohibitively expensive to do so. It is not possible to compare the costs of decontamination with a competitive method. If it were, the proposed process would be less expensive than transportation and disposal and it has the advantage of removing the liabilities from the Responsible party. After a full scale continuous pilot project is run to decontaminate a small, 500 cubic yards accumulation of this type of sludge in a California harbor, a full scale environmental project would be initiated. The decontamination of one million tons of sludge would be completed in five years.

Jan 1, 1995

By W. Addy Majewski, Kenneth L. Bickel

The U.S. Bureau of Mines (USBM) and Diesel Controls Limited evaluated a new diesel emission control system on an underground mine vehicle. The system was a catalyzed ceramic wall-flow diesel particulate filter (CDPF) combined with an catalytic converter, or diesel oxidation catalyst (DOC). This paper describes the design and installation of the system on a load-haul-dump (LHD). The results of screening tests conducted by the USBM are also given. The screening tests were conducted to determine if the device's particulate collection efficiency, regeneration temperature, and effect on gaseous hydrocarbon (HC) and carbon monoxide (CO) emissions changed over the period it was being used. The system was removed from the LHD and evaluated in the laboratory after operating for 308 and 1200 hours. After 308 hours of operation, laboratory testing revealed its particulate collection efficiency varied from 41.0 to 93.5 percent, depending on engine operating conditions. Its regeneration temperature was about 415° C. It reduced HC emissions by up to 97.6 percent, and CO by up to 95.0 percent. When tested in the laboratory after operating for 1200 hours on the vehicle, no significant change in performance was observed.

Jan 1, 1995

By Robert C. Freas

Genesis 1:28 "And God blessed them and God said he fruitful and multiply and replenish the earth and subdue it and have dominion over it." Genesis 2:15 "And the Lord God made man and put him in the garden to dress it and keep it." Depending on one's perspective, these two verses from the Book of Genesis either complement one another or are in conflict. I believe that they are complementary. What they imply is that where there is privilege, there is responsibility. Privilege comes from the fact that the Lord created the heavens and the earth and he placed man on the earth to have dominion over it. The responsibility that accrues to us comes when the Lord also said that we are accountable for how we handle that which he has given us. The very nature of our responsibilities in resource utilization or, more appropriately, resource management, has changed over time as the nation's needs and priorities have changed. Thus, I have attempted to examine, from a historical perspective, how natural resource policy has evolved, where we are now and what may lie ahead.

Jan 1, 1995

By C A. Feebrey, R A. Duncan

The Ebor Volcano in north eastern New South Wales is an eroded example of a central-type intraplate volcanic-intrusive complex. It is of Miocene age (19 - 20 Ma) and has similarities to other central-type volcanoes in eastern Australia which may represent manifestations of sub-lithospheric hotspot activity. Thick lava flows are exposed around the Great Escarpment and are dominated by a tholeiitic basaltic suite, ranging from ol-tholeiite to qz-tholeiite to icelandite with ages of 19.2 - 19.6 Ma. On its western edge, the tholeiitic lava suite probably overlies remnants of basanite flows belonging to the Eocene (~48 Ma) Doughboy province, but elsewhere, minor alkaline basaltic lavas may be coeval with the tholeiitic suite. Several felsic bodies were emplaced into the volcano at ~19.0 - 19.2 Ma and include subalkaline and peralkaline types. The Crescent Complex is a Miocene-age, strongly differentiated mafic to felsic intrusion in basement rocks and centrally located in pre-erosion reconstructions of the Ebor Volcano. It is interpreted to be a major feeder for the tholeiitic lavas based on age and composition. Evolution of the dominant tholeiitic suite proceeded from a parental ol-tholeiite magma, through qz-tholeiite, icelandite and small volumes of felsic rocks by fractionation of plagioclase, olivine, clinopyroxene and titanomagnetite, accompanied by enrichmentof SiO2, SFeOlMgO, alkalies and HFSE.

Jan 1, 1995

By Djona M. Gaballah I.

Selective chlorination of unroasted and roasted spent hydrorefming catalysts was studied between 300 and 600°C using the following gas mixtures : C12+CO, C12+N2 and CI2+air. Such materials contain Co, Ni and Mo compounds supported by alumina and/ or silica. They also contain variable amounts of V compounds, C, S, etc., accumulated during the life time of the catalyst. Direct oxychlorination of the C+S rich sample allows higher extraction rates than those obtained by the carbochlorination of the same roasted one. It seems that the roasting step doesn't favor the economic metals' recovery. Results of the chlorination of C+S poor spent catalysts, in the presence of CO, in the chlorinating gas mixture, or of carbon added to the sample, were comparable. Cobalt and nickel chlorides were .extracted from the chlorination residues by their dissolution with acidified water, whereas molybdenum and vanadium chlorinated compounds were recovered by selective condensation from the vapor phase. The recovery rates of valuable metals as well as the selectivity were higher for the chlorination of spent catalysts than results obtained by the hydrometallurgical processing of the same sample. Results of the scale-up of the oxychlorination of the unroasted sample confirmed those of the laboratory scale. The global recovery rates were about 88 pct of cobalt, 93 pct of molybdenum and 76 pct of vanadium. The carbochlorination was applied to the recovery of W and Ti from Denox catalyst that is a carbon and sulfur free one. Recovery rates higher than 99 pct at temperatures lower than 500 °C could be obtained. This may indicate that the chlorination process can be applied to the treatment of various industrial wastes or by-product containing transition and/or refractory metal compounds A flow - sheet for the pretreatment of these materials is proposed.

Jan 1, 1995

By Federico Chavez

The process for recovering lead from battery residues used in several Mexican Plants include lead blast furnace and rotary furnaces. The formers are basically fed with recycled batteries together with the necessary additives to produce metallic lead. One of the by-products generated in the blast furnace is a dust mainly formed by lead sulfide. The rotary furnace is used to recover lead .from lead batteries, dross from the refining-alloying process and the leady fines produced in the blast furnace. This paper describes thennodynamic analysis made to the rotary furnace process to understand the effect that each component of the system has upon the lead recovery. In order to enhance the process, the influence of iron chips composition and excess coke on slag viscosity is discussed. A computer optimization program . has been developed to design the furnace charge based on material and energy balances, .together with the thennodynamic equilibrium calculation.

Jan 1, 1995

By Wolfgang Pietsch

Roller presses were first invented in the middle of the 19th century, for the economical size enlargement of coal fines as fuels. Coal briquettes became quickly accepted for industrial and domestic use giving rise to a large and sucessful industry, particularly in Europe, Japan, and North America. When, towards the middle of the 20th century, coal was more and more replaced by other energy sources, such as electricity, gas, and oil, roller press manufacturers searched for alternate applications of this equipment. In addition to contemporary coal briquetting, in fields such as smokeless fuel and form-coke, it was found that redesigned and modernized roller presses, which are now capable of exerting high forces, are versatile machines for many tasks in mineral processing. Today they are used for: - the "classic" pressure agglomeration and - the "new" high pressure comminution. In pressure agglomeration, the characteristics of fine minerals are improved by forming briquettes or granulated products from compacts. During size enlargement with roller presses briquettes are directly obtained while granular materials are produced by crushing and sizing of compacted sheets. The processes are carried-out essentially dry and often do not require binders other than those inherently contained in the feed and "activated" by the high forces and/or elevated feed temperatures (e.g. hot briquetting). Therefore, no foreign materials (impurities) are added. Another advantage of the technology is, that wide particle size distributions are acceptable or desirable as feed materials, including millimeter or even centimeter sized particles. Plastic particles deform and brittle materials are crushed during pressure agglomeration. A relatively new application of roller presses in mineral processing is the utilization of the crushing effect when brittle materials pass the nip area between the rollers. It was found that this crushing mechanism is very efficient thus saving energy, particularly in grinding circuits handling large capacities. The paper introduces the fundamentals of the process and describes the design as well as applications of modern roller presses in mineral processing.

Jan 1, 1995

By R. F. Dawson, A. S. Bagnall, K. Barron

"At Smoky River Coal Limited (SRCL), economic occurrences of structurally thickened coal deposits form attractive surface mining targets. These steeply dipping, structurally complex deposits require that special attention be given to pit wall design and operational practices.Where anchor support is feasible, there is potential for reducing footwall waste requirements and/or increasing coal recovery. SRCL has used rock anchors to support footwall slopes since 1985. This paper outlines design considerations and performance of rock anchor support systems at SRCL.Three case histories are included that illustrate the design process for supporting steeply dipping footwall slopes using rock anchors.IntroductionWestern Canada contains vast reserves of high grade coking coal largely located in two belts within the Rocky Mountain Foothills straddling the Alberta/British Columbia border. There are about one billion tonnes of ""clean"" coking coal reserves (Romaniuk and Naidu, 1986) situated near existing mining infrastructure. Within the reserve areas shown in Figure I, a total of six producers operate 10 large mines linked with ports situated on Canada's west coast. Al! of the producers operate conventional shovel/truck surface pits.Surface mineable reserves within some of the mountain coal mines are located on dip slopes or where the geologic structure has thickened the coal near the surface, creating low strip ratio targets. Footwall slopes in these mines are developed parallel to bedding, thus minimizing waste extraction and preventing undercutting of potentially unstable strata. The base of the mineable coal measures in both north and south regions is marked by massive quartz sandstone units (Torrens Member and Moose Mountain Member) which often form the footwall. Footwalls developed within this basal sandstone unit can attain very high unbenched heights often with little risk of instability. In cases where the footwall is developed on weaker strata above this basal unit, stability considerations control slope height when bedding dips exceed about 30°. In these situations it is desirable to assess the benefits of artificial support to increase the unbenched footwall slope height."

Jan 1, 1995

By Andrew Case

The Port Nickel facility in Braithwaite, Louisiana, is known for pioneering hydrometallurgical processes for the 'separation and recovery of nickel, cobalt and copper. Ten years ago, in 1985, a new CRI-MET process for the recovery of molybdenum, vanadium, nickel, cobalt and alumina from spent catalysts was developed and implemented. Spent- catalysts from the petroleum industry consietute the majority of feed. These are not only a valuable-source of metals, but due to EPA regulations are frequently classified as hazardous under RCRA. Molybdenum and vanadium are selectively leached in an oxidative hydrothermal step. Alumina is then extracted in a caustic digestive leach. The unique technology produces four primary commercial products l molybdenum trioxide, vanadium oxide, aluminum trihydrate and nickel-cobalt concentrate. This paper discusses the process, modifications. during ten years of operation, and the relationship of these modifications to the future of the catalyst recycling business.

Jan 1, 1995

By Baozhong Zhao

The direct smelting of copper concentrates to copper metal in a single furnace offers environmental and energy advantages over conventional two-stage copper smelting processes. However, the direct copper making results in unacceptably high level impurities (As, Sb and Bi) in the anode copper. Experimental studies have shown that it is possible to remove these impurities from molten copper by injection of sulfur-hexafluoride. This paper discusses the experimental findings on the influence of various factors on the rate of removal of impurities, such as the impurity inter-effects, initial oxygen content in the metal and injection rate of SF6.

Jan 1, 1995

By Arthur P. Chaves, Lauro S. Norbert Costa, Adão B. Da Luz

A series of bench-scale bleaching tests have been carried out on kaolin samples from the Rio Capim area( northern Brazil) at CETEM/CNPq. The whole sample has been homogenized and submitted to particle size separation, when the + 44 µm fraction has been discarded, prior to being bleached. The main objective of this series of tests has been to evaluate the possible effects of interactions among variables which are believed to play important roles in the bleaching operation on the efficiency of the process itself in terms of the brightness achieved in the final product The tests have been planned according to a classical four-variable, two-level factorial technique. The chosen variables have been the pH, sodium dithionite addition, aluminium sulphate addition and bleaching time. The study has shown that, apart of time, all other three variables are significant. None of the interactions among them have shown to be of significance. Brightness numbers close to 88 have been obtained in the products, which represents an improvement, since brightness for the non-bleached - 44 µm Rio Capim kaolin sample averages 83.

Jan 1, 1995

The generation of acid mine water is? due to the oxidation and weathering of sulfide bearing tailings and overburdens. Ferrite precipitation prooess has been applied to treat acid mine water. The conventional ferrite preC1pitatlon requires air oxidation at high temperature, or long aging time or addition of magnetite powder ,as promoter. In this investigation, a modified ferrite, precipitation process is developed by which magnetic ferrite can be produced at an ambient temperature. Acid mine waters from Berkeley Pit (Montana, U. S. A.) and from Noranda Tailings (Quebec, Canada) were used. The co precipitation of heavy metals from these two acid mine waters is studied as a function of FeIM molar ratio, oxidation time and settling rate under applied magnetic field. The investigation indicates that the modified ferrite co precipitation can remove substantially all of the, dissolved metal ions from acid mine water. The ferrite product obtained after precipitation' is characterized by XRD, SEM, BET and saturation magnetization. The results show that spinel ferrite, precipitation can be achieved at room temperature and the saturation magnetization of ferrite product from,acid mine water is comparable to that of pure ferrites.

Jan 1, 1995

By Y. Wang, E. Forssberg, R. J. Pugh

The coagulation of dispersed ultrafine weakly-magnetic oxide mineral particles (e.g., natural hematite and chromite) in an external magnetic field can be described by interparticle forces. Essentially, coagulation occurs when the short-range London-van der Waals interactions and the long-range magnetic forces outweigh the stabilizing electrical double-layer repulsion. Using the classical colloid chemistry theory, the various components of the potential energy for different-sized particles at a series of ionic strengths and magnetic field intensities were calculated. The results of this theoretical analysis were then related to the results obtained from experimental studies in which the magnetic field-induced coagulation of the ultrafines of natural hematite and chromite in aqueous suspensions were investigated using a laboratory-scale electromagnetic solenoid. The experimental results relate the coagulation process (as determined by magneto-sedimentation analysis) to the particle size, the slurry pH and the external magnetic field. In the magnetic fields, the maximum coagulation occurred near the pH of zero-point-of-charge (pHzpc) of the minerals (where the electrostatic double layer repulsion was reduced to a minimum) enabling the particles to enter the "primary minimum" energy sink. On the other hand, in cases where the electrostatic repulsion was not suppressed, the long-range magnetic forces enabled coagulation to occur in the "secondary minimum." This caused the formation of chains that appeared to be relatively stable during sedimentation.

Jan 1, 1995

By Robert J. Timko, Lincoln Derick

This work is a follow-up to previous research that attempted to predict the location of spontaneous heating episodes in underground coal mine pillars. The objective of the original work was to see if the data obtained by commonly used detection methods could accurately predict spontaneous combustion episodes in coal pillars. Data accumulation during the study was enhanced when a spontaneously generated fire occurred within one of the pillars being examined. The fire provided researchers with realistic data that could be used to determine if fire prediction was possible. Results from the initial study found that the atmospheric status equations that were used provided little advance notice that combustion would occur where it did. This study reevaluated the accumulated data by applying it to recently developed equations and compared these results with previously obtained information to determine if a combination of these techniques could more effectively predict impending combustion.

Jan 1, 1995

By K. N. Han

The dissolution kinetics of cobalt in iodine/ iodide solutions were investigated using a rotating-disc technique. Variables studied included temperature, rotating speed, concentration of lixiviants and the pH of the solution. The overall dissolution reaction appeared to be limited by the mass transfer of tri-iodide through the diffusion boundary layer with an Arrhenius activation energy of <16.2 kJ/mol (4 kcal/mol) over the temperature range of 2 to 42ºC. The pH of the solution had little effect, as long as the pH of the solution was <8. However, when the pH of the solution became >8, the dissolution rate decreased dramatically, due to passivation. The rate of dissolution was in good agreement with the dissolution model developed by the authors earlier.

Jan 1, 1995

By William D. Riley

The U. S. Bureau of Mines has developed technology to recover by-product materials from aluminum scrap using engineered scavenger compounds (ESC). ESCs are structural oxides with a channel or tunnel structure that allows them to hold ions of a specitksizes and charges. The scavenging reaction is easily reversible allowing the ESC to be recharged for continued use and the ion is recovered as an electro deposit. Key features of this novel technology are; a) ESC ,systems are designed to have a high degree of selectivity for a desired ionic species. b) The recovered mater.ial requires little or no additional reprocessing prior to reuse. Two current uses for the ESC technology that are described in this paper are the removal and recycle oflithium (Li) from lithium aluminum (Li-AL) alloys; and, using ESCs as a replacement for the conventional demaging (magnesium removal) technology used by the secondary casting industry. Research indicates that the ESC technology proposed for both these applications has either &apos;distinct economic and/or environmental advantages over previously employed methods of recovering. metal values from aluminum scrap.

Jan 1, 1995