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By Murdoch Mackenzie

"Organic Polymers used as gangue depressants are classified according to their chemical structure. Absorption mechanisms for these reagents at the mineral - water interface are reviewed. The method of selecting these reagents for a particular flotation system is discussed. Details are given of methods of reagent solution make-up and distribution. Plant addition policy is reviewed.”

Jan 1, 1986

By Z. Sun, H. A. Davies

"Current understanding of the mechanisms by which glassy and crystalline thin ribbons are formed in high speed continuous casting processes is considered. A computer model of the combined heat and momentum transfer during melt spinning has been developed. The influence of roll velocity and of heat transfer coefficient (between the melt and the roll) on the temperature and velocity distributions within the melt puddle is analysed and the thickness of the extracted ribbon computed. The relative importance of heat and momentum transfer under different conditions is assessed and differences between the casting of crystalline and amorphous strip highlighted.IntroductionHigh speed continuous casting of thin metallic ribbon and strip is currently of considerable interest both to metal processers and to those studying process mechanisms. The practical interest arises both from the potential economic benefits to be gained from a shorter and more energy-efficient production route and from the ability to obtain extended and uniform thin strip having a metastable microcrystalline or amorphous structure with enhanced or unique properties. The latter arise from the rapid solidification associated with the cooling of very thin sections of melt brought into intimate thermal contact with one or two rapidly moving heat sinks.The principal processes for casting thin strip include free jet, chill-block melt-spinning (GBMS) (1), melt drag (MD) (2), planar flow casting (PFG) (3) and twin-roll casting (TRG) (4). For the first three of these, all essentially variants of melt-spinning, melt flows through a nozzle onto the circumferential surface of a rapidly rotating roll, whereas for TRG the melt passes into the nip between two contra-rotating rolls. We shall be concerned in this paper with the single-roll melt spinning processes only. For these, a puddle is established where the melt contacts the roll surface and the length of this puddle l is a function of the process conditions, notably the circumferential velocity of the roll Us and the volumetric flow rate of the melt Q. The contact time between any point on the roll surface and this puddle, or residence time eR(= l /Us) determines the thickness of ribbon t extracted from the puddle. This thickness, in turn, partly governs the cooling rate T and the amount of undercooling in the melt and thus the microstructure of the solidified ribbon."

Jan 1, 1986

By R. H. Zeng

Many subsidence researchers in the U. S. have developed new empirical function methods to predict subsidence, or attempted to validate some empirical functions developed by foreign researchers for use in the U. S. An attempt is made in this paper to develop a new empirical function to predict a surface subsidence basin due to longwall mining. In the U. S., the emphasis of empirical methods for the subsidence prediction over longwall panels has been in large part on determining the profile functions for the major cross-sections of a subsidence basin. In this approach, the surface monuments are usually laid out along the major cross-sections and thus, the subsidence profiles developed are restricted for subsidence prediction along the major cross-sections. However in practice many monuments or surface structures for which subsidence prediction for damage evaluation is required, are not laid out along the major cross-section of the basin. In such cases, it is difficult to get either the empirical profile function for the cross-sections where these structures are located or to predict their subsidence based on the profile function developed for the major cross-sections. Therefore, there exists a strong need to develop a subsidence basin function with a reasonable degree of accuracy, which can be determined or confirmed by the data of scattered monuments on a surface basin. The same subsidence basin function can also be used for prediction of subsidence for any arbitrary points over a longwall panel. In 1982, He (1) proposed the clastic theory, for which he developed the basic differential equations describing the movement and deformation of overburden due to underground mining, and performed the selection of best solution for the equations. He found that the Weibull dietribution is the optimal solution. The Weibull distribution has three parameters that vary to fit the subsidence profile so well that the profile function derived from it provides a high degree of accuracy in subeidence prediction. However the results

Jan 1, 1986

By Bof J, Lowe S

BHP's newest colliery on the Southern Coalfield Is Tower Colliery. It is situated near Wilton some 60 kms south west from Sydney. It commenced its operations in 1978 and since that time has experienced considerable roof problems. In its eight years of operations, production has been 936 687 tonnes to December 1985. To a certain extent this is a reflection of the ground control r,,b1cros present in the colliery. paper out Iines the signif mt g,, logical features that are known to exist in the colliery and their influence on roadway development. Faulting has hindered the mine's development and an igneous intrusion has had outhursting associated with it. The prevailing roof rock has also had an impact on the roadway conditions. The paper will look at intersection deformation in present workings. Extensometers have been installed in these areas and provide measurements to verify visual observations. The results show a significant increase in roof movement as the roadway is developed from a single heading, to a T-intersection and then Into a four-way intersection.

Jan 1, 1986

By L. R. Shotwell, C. F. Voss, R. J. Bastian

Pacific Northwest Laboratory (PNL) currently supports the U.S. Department of Energy's Office of Civilian Radioactive Waste Management in developing and evaluating analytical methods for assessing the suitability of sites for geologic disposal of high-level radioactive waste. The research includes consideration of hydrological, geomechanical , geochemical , and waste package components and the evaluation of the degree of coupling that can occur between two or more of these components. The PNL effort and those of other research groups investing potential waste sites in the U.S. and abroad are producing a suite of computer codes to analyze the long-term performace of the proposed repository sites. This paper summarizes the ongoing research in rock mechanics at PNL involving flow through jointed rock. The objective of this research is to develop a methodology for modeling the coupled mechanical-hydrological process of flow through joints and then attempt to validate a "simple" model using small -scale laboratory test data as a basis for judging whether the approach has merit. This paper discusses the laboratory tests being conducted to develop s joint behavioral constitutive model for the numerical method under development and the modeling approach being considered.

Jan 1, 1986

By M. J. U. T. Van Wijngaarden, R. J. Dippenaar

An electrochemical technique based on the solid oxide galvanic cel Mo / Mo + MoO2/ ZrO2-MgO / Fe + (FexO)slag + Ag / Fe was used in a determination of FexO activities in liquid slag systems. The emf measurements, scanning electron microscopy, and microprobe analysis of the cross-sections of the electrolyte tubes used in direct contact with the slag melts indicated that slag attack did not affect the open-circuit emf values during normal cell operation, The reliability of the cell was confirmed by the good agreement between the standard free energy of formation of liquid Fep obtained in the present study and those reported in the literature, The FexO activities were determined in FexO -CaO and FexO-SiO2 slags at 1673 K, and are in good agreement with those measured by the conventional gas-equilibrium technique. The experimental technique was successfully extended to the measurement of Fe2O activities in the complex slags that are used for the external desilliconization of the hot metal product of the blast furnace.

Jan 1, 1986

By J. Herman

The Mid-Continent Geophysical Anomaly (M.G.A.) which extends from Michigan into Wisconsin, Minnesota, Iowa, Nebraska, and Kansas, has recently been the object of intense preliminary oil and gas exploration activity involving widespread land leasing, seismic data collection, permitting of deep exploratory holes and other activities (Paul et al., 1985). This report describes the remote-sensing techniques and results of the application of these techniques to study the geology of the M.G.A. and the surroundings in Iowa. In early 1981, Coal Valley Natural Resources contracted Geospectra Corporation to find a large, (100,000 acres or larger) lease block for wildcat oil and gas exploration. The southwest Iowa area was chosen for several reasons. First, southwest Iowa contains the northeast portion of the Forest City basin (Figure 1) which has produced oil and gas from numerous fields in Kansas, Missouri, and Nebraska (Landes, 1970; Petzet, 1982).

Jan 1, 1986

By R. Norman Holme

Sulfonate promoters and collectors were originally developed as relatively inexpensive anionic collectors to selectively concentrate the iron-bearing minerals in low grade iron ores and to remove iron and other mineral contaminants by flotation in the processing of glass sands, feldspar and other ceramic raw materials. The first reagents produced were effective collectors for such iron oxide minerals as goethite, hematite, limonite, magnetite and siderite. Further development has resulted in additional reagents with a broadened application to the selective flotation of a variety of nonsulfide and nonmetallic minerals. The products in this group are anionic sulfonate-type promoters, natural petroleum sulfonates, and synthetic modified sulfonates. Beyond their applications to iron-bearing minerals, the sulfonate collectors have gained commercial use in the flotation treatment of barite, celestite, fluorite, apatite, chromite, industrial garnet, kyanite, mica, rhodochrosite and cassiterite. in addition, extensive laboratory studies indicate their potential suitability for flotation of the following minerals: Anatase Anhydrite Bauxite Beryl Calcite Chlorite Some Copper Carbonates Corundum Dolomite Hornblende Huebnerite Ilmenite Lepidolite Magnesite Phosphate Minerals Rutile Scheelite Spodumene Sillimanite Talc Tourmaline Wolframite Zircon Sulfonate promoters are water soluble or dispersible liquids, syrups or pastes of varying viscosity with colors ranging from dark blackish-brown to clear. Customarily, they are fed to the conditioner or flotation as 5% to 30% water solutions or dispersions. In addition to their normal collector activity, certain of these products display notable frothing characteristics. Improved collector efficiency and adequate froth control can frequently be obtained by employing mixtures of sulfonate reagents, of ten with results quite markedly superior to those achieved with equivalent dosages of the individual promoter alone. Reagent requirements will vary with the type of mineral being treated; however, a general overall range of 0.13 to 2.0 kg/metric ton (0.25 to 4.0 lb/ton) of feed should cover most applications.

Jan 1, 1986

By Rodger C. Fry

Underground coal mining has been active within the East Mountain property since the mid 1950's. As a result, coal from two seams has been extracted within large areas allowing surface subsidence to occur. Monitoring of subsidence annually, began in 1981 using on the ground conventional monumentation, surveying and photogrammetric monitoring. The data collected has shown the time benefits of photogrammetry and the relationship between observed subsidence and the geometry of the mined out area below.

Jan 1, 1986

By Alan G. MacKinnon

Loads and stresses from pile driving are increasing from heavier piles and more powerful hammers. Stresses can be dangerous to equipment stability. Equipment developer MacKinnon tells how to compute stresses for all positions of the crane boom and angles of pile batter. From a paper presented at the DFI-University of Hawaii Seminar, April 1985.

Jan 1, 1986

By Kepplinger W

The KR Process is a joint development by VOEST-ALPINE, Austria and its subsidiary company KORF ENGINEERING, Germany. This new technology allows production of hot metal on the basis of non-coking coal. The KR Process is based on the idea of separating the process steps realized in the blast furnace (generation of reduction gas, reduction of iron oxide and melting of the reduced iron) and including coking of coal. These reactions are carried out in two reactors: - the melter gasifier, where non- coking coal is coked and gasified into a high quality reduction gas and hot prereduced iron is melted. - the reduction furnace, where iron oxide is reduced by the reduction gas generated in the melter gasifier and discharged in a hot state. In order to prove the process a pilot plant has been set up in Kehl/ Rhine in 1981 with a nominal capacity of 60.000 tpy.

Jan 1, 1986

By R. Michael Craig

The flood basalts of the Columbia Plateau in eastern Washington State are under investigation for suitability in siting a deep geologic repository for high-level radioactive waste. To support safety and feasibility evaluations of the proposed repository construction and operation, an assessment is necessary of the potential for inflow of groundwater to the repository excavations from the surrounding saturated rock. Preliminary estimates of inflow are presented using simple models appropriate to the current understanding of available data. Both normal and bounding analyses are presented.

Jan 1, 1986

By Brian K. Failon

Scale formation is a problem that affects many mineral processing systems because the processes require the use of large volumes of water. Scale composition may vary from circuit to circuit, but the scale deposition mechanisms and needs for prevention are often somewhat similar. Likewise, there is a degree of commonality in the prediction, detection, and elimination of scaling conditions in various water systems. This paper briefly reviews some of the conditions which lead to scale formation, as well as some of the common problems associated with unchecked scale growth. The primary focus of the paper is on the variety of chemical scale inhibitors available for use in mineral processing circuits, and the actions of each type. The means of predicting and detecting scaling tendencies are also addressed, and include both direct and indirect methods, i-e., stability index determination and chemical analysis of deposits.

Jan 1, 1986

By R. W. O. Kersten

The main objective of The South African Institute of Mining and Metalurgy is to identify the needs of the mineral and metals sector of the South African economy, and to initiate the means by which the requirements for technology and scientific knowledge can be satisfied. To achieve this, the Institute organizes schools to promote technology transfer and to satisfy the needs of its members for continuing education by the exchange of technical information, the communication of ideas, and the identification of technological problem areas.

Jan 1, 1986

By R. M. Tyson

Sulfides present in the troctolitic and footwall rocks are placed into one of three major zones (hornfels, cloud, and basal) on the basis of their stratigraphic position and mineralogy. Hornfels sulfides, enriched in Fe, represent remobilized sedimentary sulfide. Sulfides from the Cloud Zone are probably magmatic and are enriched in PGE, Cu, Ni, and Ag. The basal sulfides, composing most of the ore, resulted from contamination of the magma by remobilized sedimentary sulfide. The basal sulfides exhibit a differentiation trend in their mineralogy and chemistry. PGE, Cu, and Ag are enriched with increasing differentiation which is attributed to fractionation within an immiscible sulfide liquid.

Jan 1, 1986

By E. L. Montgomery

Salar basins in the Andean Highlands of Northern Chile contain ground-water resources which could be used to satisfy requirements for the mineral industry in the region. Salars occur in arid zones; average precipitation is about 200 millimeters per year at altitudes of about 4,000 meters, and average annual evaporation is two meters or more. The salar basins are hydrogeologic sinks where water flows from recharge areas at the margins of the basins to discharge areas at the salt encrusted salar at the lowest point of the basin floor. Groundwater circulation occurs principally in the alluvial and fractured bedrock aquifers. Results of pumping tests for exploration and production water wells indicate a range in maximum sustained pumping yield of 62 to 126 liters per second, and where abundantly fractured, ignimbrite comprises the most prolific aquifer. Chemical quality of groundwater is good. Long-term pumping from properly located production wells in the salar basins would result in lowering of groundwater levels and salvage of water in areas where groundwater is lost via evaporation.

Jan 1, 1986

By J. M. Keating, R. L. Wiegel

Those processing plants which depend on flotation for their mineral separations are always looking for reagents which are cheaper, more selective or in some other way may provide improved economic performance. This paper describes the rationale for and some results from applying a statistically based approach to reagent testing in those flotation plants which still rely on experienced operators for manual flotation control.

Jan 1, 1986

By L. S. Jen

The seven most important base and precious metals produced in Canada are copper, nickel, lead, zinc, molybdenum, gold and silver. Because much of Canada's mineral production is exported in the form of concentrates, it is of special interest to keep track of the production of these various concentrates and the capacity utilization of the concentrators producing them. Annual data surveys on individual concentrators, coupled with the interactive capabilities of the computerized mineral product ion system through a custom-tailored, fairly low-cost computer system configuration are used for ongoing monitoring. Rapid analysis of concentrator production can be carried out on a disaggregated basis that allows policymakers to see specific reasons for significant changes over the years.

Jan 1, 1986

By L. R. Bower

"This paper describes a highly versatile variable speed unit with a torque multiplication feature as a direct replacement for a fluid coupling .The unit is comprised of a modulating clutch with torque converter and lock-up options.The UCD does not start or stop the motor. This is carried out in the normal manner.The UCD continually monitors and rapidly regulates the output speed to the requirement of a set point demand from input signals or a pre-set program with full manual override.The pre-set program can include start and stop ramps, top speed and minimum speed regulation and also mid-speed set point with security for man-riding, etc. Speed variation is from zero to 100% on a constant duty basis.The input signals can be from any source, e.g. belt weigher. load profile bunker probes, mine monitoring system, etc.The UCD when fitted with a torque converter has a torque multiplication feature which automatically provides a starting torque up to two and a half times greater than the full load torque without exceeding the normal motor power levels.IntroductionIt is common practice in the mining industry to drive conveyors, whether they be belt or chain, through a transmission system incorporating a fluid coupling between the driving motor and gear-box .However, there are drawbacks and in an effort to attain a better degree of drive and control, two-speed motors - inverters cycle- converters - hydrostatic drives, etc ., have been introduced."

Jan 1, 1986

By Peter M. Bartlett

The Republic of South Africa ranks among the world leaders in both reserves and production of numerous land-based mineral commodities. Over the last three decades, however, South Africa has also identified several commodities that may exist in commercial quantities in the marine environment. The major targets include 1) placer diamonds; 2) titanium- and zirconium-rich beach sands; 3) sedimentary and concretionary phosphorite and glauconite deposits; 4) manganese nodules; and 5) hydrocarbons. South Africa ranks second in world reserves of diamonds and has potentially enormous sea resources. Diamonds are currently recovered on the Atlantic side from ancient beach gravels in the Northwest Cape Province and from the seabed south of the Orange River to Lamberts Bay. Approximately 100,000 carats (or just 1% of South Africa's total annual production) are produced each year from offshore operations. DeBeers is investing approximately $5 million per year on sea prospecting activities and currently operates three vessels in offshore recovery operations. Diamonds recovered at sea will remain a small percentage of total production because of huge land-based reserves that are mined at a fraction of the cost of seabed operations.

Jan 1, 1986