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By S. G. Malghan, W. H. Moyer

In reference to the section "Excess pyrite," the author discusses difficulties in separating chalcopyrite from pyrite. A technique does exist, and has been used commercially, for the flotation, separation, and recovery, if desired, of both chalcopyrite and pyrite. The method was described in Mining Engineering, March 1966, "An Improved Flotation Method for Cornwall Sulfides." While it was not used on a porphyry copper ore, it was used on a chalcopyrite- pyrite-containing ore and might well have application. Both sulfides, chalcopyrite and pyrite, were floated simultaneously using xanthate as a collector and MIBC frother to produce a cleaned sulfide product. This concentrate was then thickened and conditioned at high solids with aeration and lime to a pH above 12.0 for a period of 1.5 to 2 hr. A supplemental suppressant, such as cyanide, could be used if necessary to sharpen the subsequent separation; however, it was not required at Cornwall. The conditioned sulfides were floated with two stages of cleaning to produce a high- grade chalcopyrite froth product and a pyrite sink product barren in copper. The separation at Cornwall gave a 28.6% Cu grade chalcopyrite product and a pyrite analyzing 0.06% Cu. A desliming step on the raw ore initially used at Cornwall for a period of time was later discontinued. Advantages to be found in using a strong sulfide collector, such as a xanthate, is the rapid flotation it induces and, generally, an ability to float at a coarser grind. A following regrind circuit could be used to give maximum liberation and produce a clean sulfide concentration. The "differential" separation is concerned primarily with grade and with assuring a barren pyrite for maximum recovery.

Jan 1, 1987

By Hans Hamrin

Three drill-blast cycles of 3.1 m advance achieved in one working shift of 7.5 hours at the Holsfjorden Tunnel project in Norway. The tunnel, 5235 m long, with a cross section of 8.6 m2, was completed several months ahead of schedule. This remarkable performance was achieved by a crew of 16 men, using machines specially designed for small tunnel excavation. The integration of drilling and charging into one unit, mucking and transport in another, reduced non-productive time considerably. The average cycle time of 140 min made it possible to complete three rounds in one 7.5 hours shift.

Jan 1, 1987

The Proterozoic Pb-Zn deposits of the Gulf of Carpentaria, Australia, include HYC (McArthur River), Mt. Isa, Dugald River, Lady Loretta and Hilton. Two seamingly incom- patible depositional models have been proposed to account for their origin. Finlow-Bates (1980), Large (1983) and Russell(1983) classify these-deposits as sediment-hosted submarine exhalative deposits. This class includes Rammelsberg, Meggen, Silvermines, Sullivan and others. In contrast, a lacus- trine, shallow-water origin has been advocated by Williams and Logan (1981), Logan and Williams (1984), Muir (1983) and Eugster (1985). The discrepancies between these two models can be removed by creating a separate class, that of continental sediment-hosted exhalative deposits.. HYC., Mt. Isa and Dugald belong to this class and their sediments were deposited in shallow, alkaline lakes. Metal- rich, hot, Na-Ca-Cl brines entered the basins along boundary faults and interacted with pore fluids and sediments, depositing-Cu-Zn-Pb sul- fides. Similar brines entered the Lady Loretta basin after marine flooding, depositing sulfi- des and barite, placing Lady Loretta into the class of marine Sedex deposits.

Jan 1, 1987

Brief summary of results obtained by a French-Japanese cooperative study on the bottom of trenches around Japan. The geophysical prospection, multi beam echo sounding and direct observation with submersible dives of the trench bottom clarified the details of the subduction of oceanic plates. It may be noted, among many new facts found: 1. The subduction and geologic structure resulted from the process is different according to the nature of subducting oceanic plate, and the geology of the land behind the trench. Thus the Nankai trough characterized by the developpement of accretionary prisms is contrasted to that of the Japan Trench where the basement rocks are exposed on the land side cliff of the trench wall. 2. The compressional tectonic situation prevailing in the trench bottom provokes the venting, along the fissures on the bottom, of water contained in sediments. Hydrocarbons contained in the sediments are comming out with water and give nutrients for bacteria. Clams, tube warms, sea slugs and shrimps are taking these bacteria as their food and biological communities with exceptionally dense population for the deep sea of more than 3000 meters in depth are formed on the field of accretionary prism and wall of the land side cliff. 3. An intense compressional tectonic field resulted from the subduction is inducing the transition from the subduction of oceanic plate to the collision of a part of the plate to the continental plate.

Jan 1, 1987

By T. A. Edison

A distinct hydrocarbon maturation anomaly coincides with the Gold Acres open pit, Nevada (Figure 1). Both atomic hydrogen to carbon (H-C) ratios and reflectance measurements of contained organic matter indicate significantly higher maturity in samples collected within the confines of the open pit than in samples from the surrounding region (not shown in Figure 1).

Jan 1, 1987

The accuracy of an ore reserve is only as good as the geologist's understanding of the deposit. The methods that are applied to resource and reserve estimation reflect that understanding. At the Olympic Dam copper-uranium-gold deposit in South Australia, evolution in the understanding of the controls on mineralisation coupled with the changing demands of the project have led to changes in the approach to reserve estimation. The project has moved into a phase where detailed stope mining reserves are now required as distinct from global ore reserves. The complex nature of the mineralisation and the large amount of data demand that all available information be readily accessible in a flexible format. To enable the selective manipulation of geological and assay information and its characterisation, a relational database has been developed. For reserve calculations themselves, initial computations were based on a system derived from that used for the Kambalda nickel orebodies. The Olympic Dam system differed mainly in the use of statistical analyses in the estimation of grade instead of the previous polygonal area of influence weighting method, Three dimensional weighting techniques are now being used for local reserve estimates. Flexible facilities for raw data handling combined with grade estimation techniques which are commensurate with the mine geologist's understanding, produce detailed gridded and contoured ore zone models suitable for reserve calculations and stope designs.

Jan 1, 1987

By T. C. Rao

The quantum of coal fines below 6 mm in run-of-mine (ROM) coal has been increasing due to progressive mechanization of mining methods which has created a substantial incentive, worldwide, to develop suitable fine coal beneficiation techniques. The majority of the efforts have been directed toward reduction in ash/sulfur contents in clean coal. The beneficiation techniques may be broadly grouped as those based on specific gravity and surface property. The processes, which use heavy medium cyclone, water-only cyclone, concentrating tables, and spirals, belong to the former group while the latter group encompasses froth flotation, column flotation, oleo- flotation, and oil agglomeration. In almost all the gravity based techniques, it has been noted that a classification step prior to beneficiation is essential for effective treatment. In general, the effect of design and process variables on the performance of these units and also the quantification of the processes have been the main areas of research and development. In froth flotation, efforts throughout the world have been mainly to understand the effect of variables and to optimize the process. Quantification of the process has been attempted through kinetic studies and mathematical modeling. The efforts have led to the development of new reagents, machine designs, and flowsheets for a specified objective. The attempts so far with the column flotation and oleoflotation processes have indicated a great potential. Extensive R&D efforts are in progress to understand as well as to commercialize the processes. The efforts in the oil agglomeration process have been toward substantiating the inherent merits of the process by developing cheaper bridging liquids and technology to recover and reuse the oil to make the process commercially viable. Modeling of the process has also been attempted to predict the yield and size distribution of the agglomerates. This paper reviews and summarizes the recent developments in the science and technology of fine coal beneficiation processes. The current trends in R%D efforts for these processes are also highlighted.

Jan 1, 1987

By R. B. Prater

Research by the Bureau of Mines includes efforts to devise means for maximum recovery of critical and strategic metals from primary and secondary domestic resources. As part of that effort, the Bureau developed a hydrometallurgical process to recover Co, Ni, and Cu from Missouri lead-smelter matte. The process includes leaching with H2S04 plus Mn02 as an oxidizing agent, liquor purification, selective precipitation of CuS, (Co,Ni)S, and MnC03, and crystallization of Na2S04&apos; This report is concerned primarily with liquor purification, in which As and Fe are removed from the leach liquor by pH adjustment and filtration. Two variations of the purification step are described. One variation provides liquor containing <1 mg/L As and Fe but requires two solid-liquid separations, The other is achieved with only one solid-liquid separation but leads to a lower degree of purification.

Jan 1, 1987

By Nagai K, Moriyama K

Toyo smelter has been making s veral efforts to reduce and diversify energy for dealing successfully with such :n:;rgy problems as the first and second oil crises. ::,specially it is one of th:; most important subjects to substitute oil by alternative: energy source, because oil is expensive and unstable with respect to its supply. t _&apos;hercfore i was decided to propel tnC ezhstitution of coal *jr oil. in the first place, the supple- mental fuel oil in the reaction shaft was replaced by oil to coal in 1981, and then th, fuel substitution of pulverized coal was achieved in the steam superheater in 1984. 3y these fuel substitutions about 7u,&apos; of the total fuel energy at 2oyo smelter has been replaced by coal. in this paper the fuel substitu- tions at loyo smelter are described in detail.

Jan 1, 1987

By Keith G. Wallace, Gary K. Rogers

As a supplement to an analysis involving methodologies for the estimation of airflow resistance in shafts used for both ventilation and hoisting, a detailed shaft characterization survey was distributed worldwide. The survey provided detailed information which enabled verification of recommended velocities and established limitations on fill factors and relative velocities. This paper evaluates the information obtained for 37 shafts and presents a statistical evaluation of the results. Apart from airflow rates, conveyance rates, and physical characteristics, qualitative information regarding means of conveyance stability and velocity control techniques at unloading and loading points are also presented. Calculations of fill coefficient, free area velocity, and most importantly, relative velocity between the airflow and hoist, are conducted. These results are presented by frequency diagrams which illustrate the trends, as well as provide limitations for these parameters. The data illustrates that, commonly, the fill coefficient for two or more conveyances, does not exceed 30 %. A limit of 50% is suggested for a single conveyance shaft. A recommended free area velocity of 10 m/s (1,970 ft/min) for combined ventilation and hoisting shafts, is sup- ported by these results. Relative velocities of 30 m/s (5,905 ft/min) are most frequent and 50 m/s (9,840 ft/min) being a practical maximum.

Jan 1, 1987

By Thomas H. Koenning, William E. Bruce

The importance and complexity of the ventilation systems in many underground coal mines necessitates the use of digital computers to model the ventilation networks. The modeling procedures used by the Mine Safety and Health Administration (MSHA) utilize the MSHA-modified Penn State computer program. The basic techniques used by MSHA have been described in detail in NESA (now MSHA) Informational Reports 1066 and 1183 (1. 2). Two basic methods are utilized for modeling underground mine ventilation systems. The first modeling method is the use of actual air-flow, pressure, and fan-performance data acquired during a full air-pressure, air-quantity ventilation survey to develop a mathematical model of the ventilation system. The second modeling method is the design of a ventilation system using data obtained from calculation, from past experience, or from technical literature. The latter method would typically be used to design a ventilation network prior to developing a new mine. Regardless of which method is used for modeling, there is a need to know, or to calculate, appropriate resistance values to be used for airways and for the various ventilation control structures. Such data is typically difficult to obtain and this report is an attempt to summarize typical resistance values which may be used in designing ventilation networks for new mines or in simulating proposed system changes in existing mines. Illustrations are presented to show where some of the resistances typically are located and how they are modeled in mine ventilation net- works.

Jan 1, 1987

By Ushakov S

New geological and geophysical in vestigation including our detailed field observation in different regions of the Koryak upland testify that Nor- theastern Eurasia margin eastward of the Ochotsk-Chukotka belt is composed of a collage of allochtonous terranes arcs and sedimentary filling of back- arc basins, which bordered North East Siberia and Chukotka (1)1). Ancient island are assemblages are the most tipical for this region (2-4; shown by heavy line). They are marked by long (500-1000 km) volcanic belts which become younger towards the Pacific up the Latest Jurassic-Neocomi- an (2) to Late Cretaceous (3) and Pale- Gene (4).

Jan 1, 1987

A computer programming language known as GPSS is described and possible applications for the mining engineer are presented. The language is continually being upgraded with improved versions appearing about every three years. The tremendous power of the language is considered by comparing it with standard engineering programming languages, such as Fortran or Basic. Sample problems that can be solved using the language are indicated. The advantages and disadvantages of the languages are also discussed.

Jan 1, 1987

By P. Bottomley, M. Matthews

Maintaining an acceptable thermal environment in South African gold mines becomes increasingly difficult as mining progresses to greater depths where higher virgin rock temperatures are encountered. Current environmental practice offsets the resulting high heat loads by installing large refrigeration plants. However, with the continued escalation of refrigeration costs, it has become necessary to examine other methods for economically combatting the underground heat load. The Chamber of Mines Research Organization has recently been pursuing a programme to devise methods of reducing the flow of heat into underground workings at source. Although there are several sources of heat (such as machinery, men, and explosives), the most significant is that from the rock mass surrounding the workings (Bluhm et al., 1986a). The main thrust of the work has therefore been directed at predicting and devising methods of reducing this heat source. A great deal of theoretical work has been carried out on the prediction of underground heat flow. From a review of this work (Bluhm et al., 1986b) it became apparent that there are two major aspects which require attention, namely algorithms for predicting the heat flow around the advancing stope face, and a correlation of the theoretical work with accurate empirical data. In order to remedy this situation, new theoretical models have been developed (von Glehn and Bluhm, 1986), and heat flow measurements have been made in both a conventional stope (Bluhm et al, 1986a) and in a backfilled stope (Matthews u., 1987). A number of methods for reducing rock heat flow are being examined. These include the insulation of intake airways (Bottomley, 1985 ), backfilling with waste material of the worked out areas, and alternative approaches to the design of mining layouts, the mining method, and the choice of cooling strategy. This paper highlights the heat load reductions that can be achieved by backfilling the worked-out areas and by adopting concentrated mining. The first part of this paper summarizes the results of the measurements obtained in the conventional and backfilled stopes. The theoretical models are then described and comparisons are made with the measured values.

Jan 1, 1987

By Noel N. Moebs

Five LANDSAT lineaments in the coal mining region of southwestern Pennsylvania were investigated by the Bureau of Mines to determine their geologic character, relation to subsurface conditions, and the means of discriminating one from another. The investigation included earth resistivity and very low frequency (VLF) electromagnetic traverses, soil moisture sampling, and a correlation with coal mine roof conditions. The lineaments could not be detected by the methods used, suggesting that they might be a surface phenomenon unrelated to subsurface geologic structures or roof stability in coal mine workings beneath.

Jan 1, 1987

By P. J. Watson

The objective of this study was to prioritize the potential risks nuisance and biologically active dusts and fumes present in metal and nonmetal mines. This was accomplished by ranking numerical values derived from a matrix formula calculation that took into account dose, mine population, and sampling size. Data used in these calculations were obtained from the Mine Inspection Data Analysis System (MIDAS). The dusts determined to have the highest risk potential were quartz respirable particulates, mine dust, cristobalite respirable particulates, welding fume components, and nuisance respirable dust. Other dusts and fumes that were not ranked in this study, due to small sampling population, but which show a potential risk, include asbestos, talc, hydrogen cyanide, organic compound dusts, arsenic, metal dusts, and metal and nonmetal fumes.

Jan 1, 1987

By W. S. Fyfe

Gold is mobilized or made soluble under all crustal conditions given appropriate fluid chemistry with molecules which complex gold. In the surface environment chloride, thiosulphate and a host of organics may mobilize gold. In the epithermal range bisulphide appears effective as shown by the classic studies in the Taupo volcanic zone of New Zealand. In the high grade metamorphic to igneous ranges little is know but it appears that gas molecules in the system CO2 -CO-H20-S-C1 can do the job. Precipitation may occur by changes in P-T-EL-pH or boiling where such changes influence the liquid concentration. Of the known regimes information is good for epithermal systems, poor for surface lateritic environments, inadequate for high-T systems. Gold is often concentrated in bio-systems both living and dead. The influence of biosystems is little appreciated. There is a great potential for the discovery of new types of gold deposits and in particular, gold in weathering environments, gold in very high-T environments, gold in strike-slip faults and thrust regimes, and gold as a by-product in materials like coal and other organic debris. By the year 2500 we may find our noble metal resources in the asteroids.

Jan 1, 1987

In the last several years we have seen the demise of the Department of Mining and Metallurgy at the University of Melbourne, the removal of extraction metallurgy from the Department of Metallurgy and incorporation of it within a School of Mines at the University of New South Wales, and the joining of a small Department of Metallurgy with a Department of Chemical Engineering to form a Department of Chemical and Materials Engineering at the University of Newcastle. Most of these changes have been forced by the logical application of the principles of accounting, the currency for such accounting being the Whole Student Unit (WSU). It is not my intent to address the problem of attracting young people into courses in metallurgy (including extraction metallurgy) which, at present, is the only way to introduce black ink into the WSU accounting ledger. Rather, I wish to express my disquiet over the trends, illustrated by some of the above occurrences, of separating out extractive metallurgy from METALLURGY by suggesting in broad terms how a course in metallurgy should be structured. I firmly believe that the mechanical metallurgist and materials engineer need an exposure to chemical and extractive metallurgy; similarly, the extractive and process metallurgist should, in my view, have a good grounding in the interrelationships between composition, structure, and properties, this topic being the core of the basic subject physical metallurgy.

Jan 1, 1987

By B. Goard

"IntroductionCemented backfill has been placed underground in slurry form in Inco Limited&apos;s Ontario Division mines since the early 196Os. The slurry was traditionally mixed on surface at between 65 and 70 wt% solids* and transported underground via gravity through a borehole-pipeline distribution system. This method of placement, while simple and dependable, has proven to be costly because of the large amounts of transport water involved.A significant quantity of the slimes buildup on mine levels is caused by the backfill water carrying cement and other fine material out of the stopes. The level cleanup and eventual pumping or hoisting of the slimes and water back to surface result in substantial indirect backfilling costs.The cement that remains in the stope is always overhydrated because of the high water cement ratios that exist. As a consequence, high concentrations of Portland cement must be added to the backfill to produce the fill strengths required for the different mining methods.Pouring backfill at these densities also demands extensive fill preparatory work in the stopes to withstand the hydraulic heads created by the slurried fill. This, along with the delays in pouring necessary to allow for water drainage, result in significant losses in productivity.These negative aspects of slurry placed fill has led Inco Limited to investigate several methods of transporting backfill underground via pipeline, at higher densities (i.e. 75 to 95 wt.% solids). Three separate transport methods are presently being experimented with by the Company&apos;s Mines Research Department. Each utilizes a different technique or form of flow transport, i.e. concrete pumping technology, high density slurry flow, and pneumatic conveying."

Jan 1, 1987

By P. C. Garg

"IntroductionThe Central Mine Planning and Design Institute (CMPDI) of India, started planning the extraction of thick seams highly susceptible to heating in 1977by the French method of sub-level caving and/or multi-slicing. Nitrogen flushing was proposed for inhibition of heating by the author in one such project - the Kotadih colliery.Inhibition of heating was unheard of in the Indian coal industry before 1977-78. The usual practice was to seal off a district or a part of the mine or the entire mine when spontaneous heating occurred. With very little equipment in a normal bord and pillar district and a low production rate, the financial loss in capital assets and in production did not warrant any serious thought for inhibition of spontaneous combustion. With the planned advent of longwall mining, particularly sub-level caving, with heavy capital investment as well as high production potential, the sealing of a longwall face due to spontaneous heating could not be considered an appropriate solution.Principle of Inhibition of SpontaneousCombustionFrench engineers have established that a fire will not break out when oxygen is 15% or lower in the general body of the air. However, once a fire starts, the percentage of oxygen has to be reduced to 2% - 4% to extinguish it. It is this principle which has been used at Blanzy Coalfield in France to inhibit heating and it is claimed that this has retrieved the integral sub level method of mining. Nitrogen infusion has been used in Frence since 1978 to keep the oxygen content below 14% in the goaf."

Jan 1, 1987