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A price list of publications of the Geological Survey, complete to May, 1931, and with separate monthly notices of publications to (late, will be sent upon application to The Director, United States Geological Survey, Washington, D. C. A leaflet is issued each month listing new publications; it will be sent upon application to the Director, as well as Circulars containing information about topographic maps. Book publications of the Survey include (1) Annual Reports, (2) Monographs, (3) Professional Papers, (4) Bulletins, (5) Water Supply Papers, (6) chapters and volumes of Mineral Resources of the United States, (7) Folios of the Geologic Atlas of the United States and the World Atlas of Commercial Geology, (8) Topographic Folios and Topographic Maps that bear descriptive texts. Monographs, Folios of the Geologic Atlas of the United States and the World Atlas of Commercial Geology, and Topographic Folios and Topographic Maps, are not distributed free. A publication of one of the other classes can be distributed free only until the end of the fiscal year following that in which it was issued. No person can obtain more than one free copy of the same publication, and general requests for free publications, such as all of any series or all on any subject, can not be granted. In ordering publications one is requested to give both the series designation, as Bulletin 738 or Professional Paper 122, and the title. Give full address, plainly written, including county. Prepayment is required and may he made by postal, or express money order payable to the official charged with the sale of the publications. requested, as indicated in the discussion of each classification following; or it may be made in cash-exact amount -at sender's risk. Postage stamps are not accepted in payment for publications.

Jan 1, 1933

By Bernard J. Steblay

The U.S. Bureau of Mines has attempted to use ultrasonic signal travel-time measurements to measure loaded roof bolt strains. The strain measurements are then related to roof bolt loads through equations or empirical calibrations. Such techniques offer the potential of accurate, rapid bolt load measurement that does not disturb the anchotage. This report presents 6e research findings for a specific type of ultrasonic measurement instrument using a pulsed-phase-Iock-Ioop technique. This technique measures signal travel time indirectly by measuring frequency changes. A complete development of the applicable theory and detailed derivations of key equations is presented along with empirical laboratory and field results. The differences between anticipated and measured behaviors are analyzed and discussed. The report identifies problems encountered in applying pulsed-phase-Iock-Ioop technology to roof bolt load measurement and provides potential solutions to many of them. A key assumption of pulsed-phase-lock-loop theory is that driving and reflected signal frequencies will always be equal. Findings showed that not only were actual frequencies not equal but they were not stable or simply related. Reflection wave shape also was not stable. The ramification of these findings and ways to minimize their adverse effects are presented.

Jan 1, 1990

By Osvaldo A. Bascur, J. Pat Kennedy

Large metallurgical complexes have more data than a small city and much of it is "real time," changing rapidly as internal and external conditions evolve. As corporations buy and sell assets and reengineer their staff, the structures and tools that were used to understand these data are lost. The lack of an integrated approach makes the profitability of metallurgical plants lag behind that of other industries despite technical advances that have occurred in recent years. This results in significant deterioration in the ability to maintain a "smart” operation. The solution is to use the sophisticated new tools built for the Internet so as to leverage information in a familiar browser format that people can use and understand. Combining real-time infrastructure with portal technology is becoming an accepted methodology. This paper introduces real-time portals and team sites to support decision making by work- groups which require both real-time and documentary information from manufacturing assets, vendors, head office and the Internet. Workers get insight from the overall process effectiveness index based on key variables such as losses due to plant availability, performance efficiency and rate of quality. Real-time portals and smart clients are part of any real-time performance management (RtPM) solution. Three case studies in large metallurgical complexes are presented. PLANTS ARE YOUR STRATEGIC HANDICAP Information technology is arguably one of the fastest moving technologies used by the mining/metallurgical industry. However, the business model for managing that

Jan 1, 2004

By N. S. Dalal, X. Shi, V. Vallyathan

"Electron spin resonance (ESR) and cytotoxicity measurements were made on newly fractured silica to examine specifically the role of the fractured-induced, siliconbased radicals (Si· and SiO·), and silica-generated hydroxyl (·OH) radicals in the mechanism of the cell membrane damage by silica. The concentration of the Si· and SiO· radicals was controlled through decay processes, thermal annealing, and boiling, while that of the ·OH radicals was varied by using catalase, superoxide dismutase, KMnO4, Ha2seO3, ascorbic acid, and metal ions, and monitored via ESR spectroscopy. The dust's cytotozicity potential was evaluated by measuring the silica-induced hemolysis and also by determining lipid peroxidation (using linoleic acid). Prom the comparison of hemolysis and ESR results it is deduced that the radicals play little· or no role in the silica-induced hemolysis. However, the lipid peroxidation data indicate that the radicals might be involved in the initiation of an oxidative chain reaction leading to the macrophage membrane damage through lipid peroxidation. INTRODUCTIONThe biochemical mechanism of Quartz-related pneumoconiosis is still not fully understood. It is believed, nevertheless, that one event of primary importance is the perturbation of cell membranes by the dust particles (Allison et al., 1966; Allison and Harrow, 1971; Bateman et al., 1982; Parazzi, et al., 1968; Reiser and Last, 1979; Shi et al., 1989; Summerton et al., 1977). The ensuing cell-membrane damage unleashes certain lytic enzymes resulting in additional cell injury and eventual fibrosis (Nolan et al., 1981; Summerton et al., 1977). Thus considerable effort is currently being made towards the understanding of the processes by which quartz particles disrupt the membrane of a red blood cell (RBC) or a pulmonary alveolar macrophage (PAM). A simple but important method of evaluating the membrane damage potential of a dust is the hemolysis test (Harington et al., 1971). Even though this test is used routinely for screening dusts for their cytotoxicity potential, the biochemical mechanism underlying the cell lysis by many dusts, including quartz, is still controversial (Kilroe-Smith, 1974; Singh and Rahman, 1987), and this provided us the impetus for the present undertaking."

Jan 1, 1989

By Ivette E. Torres

World investment 10 all mineral and mining industry sectors is not available. However, partial information available provides some information useful for analysis. Information available in this section covers limited geographic information on investment in the steel industry, limited information for petroleum industry capital spending, and total U.S. foreign investment in comparison to the mineral-related sectors (tables 13, 14, and 15). Annual steel industry investment is available for the European Community, almost all countries within the European Free Trade Association (EFTA), Latin America, and other countries with significant mineral industries, such as Canada, Japan, and the United States. Although information was not available for 1992, data for 1991 indicate that for those countries aforementioned, total investment increased by 8 %. However, investment patterns were very different within the different groups of countries. While the European Community had a net increase of 12 %, dominated by an almost °40 % increase in Germany, EFTA member countries had a 26 % decrease in investment for the same period. Investment in EC countries was almost seven times that of EFT A countries. Japan's investment in the iron and steel industry, by far the largest of those available, almost twice that of the EC and almost four times that of the United States, increased by more than 20 %. In North America, investment in Canada and the United States decreased. Almost all of Latin America decreased investment in the sector. The notable exception was Mexico, with a 60 % increase. Changes in Mexico's investment policies of the recent past, its economic growth, and privatization of its iron and steel industry are some of the reasons for such an increase. The other country covered individually in Latin America, where investment in the iron and steel industry increased, although slightly, was Argentina. This limited information does not allow a comprehensive analysis of global industry trend, which in turn impacts many other mineral commodities, and with the transition in many countries within Europe and Central Eurasia that are now effecting the steel industries of the countries that were members of the U.S.S.R. and its CMEA partners, it is most regrettable that comprehensive and comparable data, both current and historic, on investment in this area are not available.

Jan 1, 1994

Reduce longwall equipment transfer time between panels by utilizing a predriven recovery room, and thus eliminate the premove preparation associated with most equipment recovery methods. Background and Approach The recovery point for a retreating longwall is a predetermined position near the end of the panel where mining is terminated and equipment is disassembled and removed. However, to prepare for equipment removal at the recovery point, bolting and wire meshing arc required before the recovery point is reached. Usually, preparations for equipment recovery begin about 35 ft from the recovery point, significantly impeding the normal rate of advance of the longwall and, consequently, production. Recently, BethEnergy Mines, Inc., and the Bureau of Mines cooperated to evaluate the applicability of utilizing predriven recovery rooms to improve longwall equipment recovery. A predriven recovery room is an entry driven parallel to the longwall face at the end of the panel, having standard dimensions (for that particular mine) and supported with bolts, wire mesh, and supplemental support. The preparation of this entry is completed before it experiences mining-induced effects from the approaching longwall face. This enables the face to continue to mine at its normal rate of advance until the panel is completed. The supplemental support is required to control the loads imposed by the front abutment and is the most vital component of the recovery room.

Jan 1, 1989

By C. T. Holland

Coal mining has been an important industry in the Appalachian area for many years. This is particularly true in the northern part of the area, namely, in Pennsylvania, West Virginia, and Ohio. Also, in the south a great deal of mining activity has been carried on in Alabama, Kentucky, and southwest Virginia. Some of the by-products of this activity has been the production of mineralized water from the mines in copious quantitites. The southern Appalachians have been somewhat more fortunate in that the water there has had a considerable amount of alkalinity in it, which has to a large extent eliminated some of the more undesirable aspects of mine drainage. Northern Appalachia, including central and western Pennsylvania, the Monongahela basin in West Virginia, and the Appalachian area in eastern Ohio have not been so fortunate in that coals in those areas and the top and bottom rock have, in many cases, shown considerable quantities of pyrite, and the water does not carry the carbonates found farther south.

Jan 1, 1969

By B E. De Gee, N Viviers, A Naidoo

In 2013 the Mopani Copper Mine Mufulira plant in Zambia embarked on a project that was aimed at improving concentrator recoveries. The project commenced with the automation of the milling and flotation circuits. This involved the installation of new instrumentation, namely measurement devices and actuators, and the connection of these to new programmable logic controllers (PLCs).The infrastructure changes were followed by the implementation of basic proportional-integral-derivative (PID) controllers on the PLCs. Supervisory control and data acquisition (SCADA) interfaces were also implemented to allow for switching between controller modes, inputting of setpoint variables and to provide a visual display for process monitoring. The final phase of the project involved the installation and commissioning of advanced process control (APC) solutions on the milling and flotation circuits. This work was carried out by Mintek over 21 on-site days. The APC solutions included the MillStar and FloatStar suites of advanced controllers.The MillStar control suite focused on stabilising the mill feed and mill discharge on the two primary mills as well as the flotation circuit feed. Mintek’s CyLas instruments, which provide a measurement of the hydrocyclone underflow angle, were also installed. The measurements were incorporated into the discharge stabilisation control on both milling circuits. The FloatStar level stabiliser controller provided flotation cell pulp level control on fourteen cells, including two columns.Performance tests showed that the Mintek APC system stabilised the mill feed and mill discharge while ensuring the process remained within operational constraints. The MillStar control system utilised the CyLas instrument to prevent roping on the hydrocyclone underflow. This was not always achieved under normal operation. Additionally, the flotation section was stabilised as a result of improved level control by the FloatStar control system.Performance comparisons showed that the Mintek control system improved the operation of the milling and flotation circuits resulting in a greater copper recovery.CITATION:Naidoo, A, De Gee, B E and Viviers, N, 2014. Implementation of an advanced milling and flotation control system at Mopani Mufulira copper mine, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 363–368 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Thomas L. Kesler

The Cartersville mining district, 35 miles northwest of Atlanta, Ga, has been of varying but continuous importance in the southern mineral industry during the past century. Noted chiefly for its production of brown iron ore, manganese oxide ores, barite, sienna, and magnesian limestone, the district and its environs have produced brick and tile clays, slate, gold, bauxite, and graphitic schist. Minor deposits of serpentine, sericite schist, copper ore, and red iron oxide have been prospected. The obvious deposits of brown iron ore, together with some associated specular hematite, were mined out years ago, although a little ore was left in the workings. Moderately steady production of sienna reached a peak about 1930, then declined rapidly. Manganese mining passed through a relatively active period from the World War to 1931, but has subsided to a small but rather constant output for the Birmingham market. However, the White Manganese Corporation has prepared for possible increased production by constructing a new washer capable of handling about 300 tons of ore per day. Principal activity in the district proper has centered for some years in the production of barite and magnesian limestone. General Geology Geologic relations of the ore deposits of this district are more or less similar to those of many Appalachian districts. The lowermost Cambrian formation, heretofore called Weisnerl in this region, supposedly partly or. wholly equivalent to the Erwin and Hesse quartzites as recognized to the northeast, is overlain conformably by the Shady† formation, also of Lower. Cambrian age. In the Cartersville district, the sedimentary rocks of these formations were folded with increasing intensity eastward, and were recrystallized.

Jan 1, 1941

By E. Topanelian

In recent years considerable progress has been made in the development and application of mathematical techniques for the solution of certain problems involving economic "strategies". Such a problem might involve, for example, the scheduling of shipments of a commodity from a number of sources to a number of destinations. The object would be to schedule the shipments in a manner so as to satisfy the destination requirements and at the same time minimize the transportation costs. The solution to such a problem is not necessarily intuitively obvious. The "obvious" solution is frequently far from optimum. If the shipments are to be made from, for example, only two sources to four destinations, the optimum schedule is readily found. However, if shipments are to be made from, say, 10 sources to several hundred destinations, even a competent and experienced scheduler may spend considerable time in finding a reasonable answer. Even then he is not sure that he has the optimum solution. Furthermore, he has no way of knowing how far from optimum the answer is. Consequently, he does not know whether he should accept this solution or seek a better one. Prior to the advent of large high-speed digital computers, little more could be done with such problems because of their great size and multiplicity of possible solutions. A problem involving 20 sources and 50 destinations would require choosing, from a very large number of possible combinations, the optimum combination of 1,000 variables. The best one could do was to utilize intuition, extrapolation from past experience, and other non-exact approaches. With a high-speed computer, however, such problems can be solved providing a reasonable computational procedure (or algorithm) can be utilized. The purpose of this paper is to describe such a procedure (linear programming) and to apply this procedure to a production scheduling problem. THE RESERVOIR PROBLEM A simple reservoir model is used throughout this analysis to illustrate the use of linear programming. Even the simplest reservoir behavior problem is nonlinear in both space and time, but if the geometry is fixed for a particular study and the time variable is quantized, the resultant system may be described by linear constraints on the variable production rates. Crude oil is available from five separate sources and is delivered to a pipeline. Sources 1, 2, 3 and 4 are ideal reservoirs and therefore are subjected to reservoir flow restrictions. Source 5 is labeled "Outside Source" and crude oil from this source is assumed to be available in unlimited quantities without considering reservoir conditions. The general problem is to determine the schedule of crude oil production from five sources which, over an eight-year period and subject to certain restrictions, will result in maximum profit. "Profit" is defined to encompass all economic factors and expenses involved in producing and selling crude oil to a pipeline facility. Such economic factors are lumped to the extent that the term represents the dollars profit from one barrel of crude oil from any of the five sources entering the pipeline system. Table 1 presents the assumed profit per barrel for oil from any of the five sources over each of the four time periods. In this chart the eight years is broken into four equal intervals of two years. The selection of four time periods of two years each and the values representing the potential profit are completely arbitrary selections for the purpose of illustrating this idealized reservoir problem. In any practical application of this work a careful economic study would have to be made in order to estimate potential unit profits for time periods as far in the future as eight years. In this particular study it is assumed that all of the potential unit profits (C) are known and fixed before the production schedule is attempted. For each reservoir arbitrary values are assigned for

By M. Berjak, D. M. Hawlins, R. B. MacGillivray

SYNOPSIS The paper describes a method of producing iso line plans using a mathematical technique for interpolating between boreholes, and its computer application. The iso line plans are used for assessing the value parameters of an ore body. The computer programme also produces means and standard deviations to supplement these iso line plans. The mathematical techniques tested for the production of a satisfactory fit of the data were the polynomial, Fourier and moving average technique. The iso line plans are used for assessing the quality of the ore and other salient features such as depth to the floor of the ore body at different points, with a view to deciding how best the ore may be mined. The plans are plotted by the computer to any scale required. INTRODUCTION To assess the economic exploitability of an ore body many tedious and repetitive calculations must be carried out. Observations of borehole or development samples have to be processed yielding measures of ore reserve and quality in each sampled area, and also measures of the worth of the ore body as a whole and of variation in quality from section to section of the ore body. The observations made on the ore (which we shall term 'value parameters') may embrace a variety of characteristics of the ore. Obvious value parameters are those directly related to the economics of mining, viz. assay values, ore body thickness and depth below surface. Other value parameters however may be almost as important. In the case of coal for example a purchasing contract may specify limits of acceptability on other value parameters such as calorific value, ash content or the percentage of volatile matter. In this case, a detailed study of these value parameters will also be crucial. This detailed study must include an assessment, not only of the body as a whole, but also the regional variation in value of the parameter. An obvious and satisfactory way of displaying this variation is by drawing iso lines of constant value parameter on a map of the ore body and supplementing this with the means and standard deviations of the value parameters taken over all boreholes. Such plans, considered together, show up the zones of significance. The relatively stereotyped nature of the operations involved in this process makes it amenable to computer solution. In order to produce iso line plans on the computer we require some mathematical formula for producing a 'valuation surface'-a mathematical

By Florian Kongoli

Slags and fluxes are important interchangeable dimensions of pyrometallurgical processes. They can increase the efficiency of the smelting, converting and refining processes and improve the quality of the final products. A good slag should have appropriate physicochemical properties such as low liquidus temperature, optimal viscosity, maximum ability to attract undesirable elements, minimum potential of attracting valuable elements, etc .. A good flux, on the other hand, when properly used, can considerably improve the physicochemical properties of the slag since by modifYing its chemical composition it could decrease the liquidus temperature, improve viscosity etc.. Consequently, the choice of a good slag and the corresponding fluxing strategies has become indispensable in most of industrial processes. However, the properties of multi component slags as well as the effect of several fluxes are known only empirically and confusion exists in the literature and in the industrial practice. In today's reality of frequent changes in the composition of raw materials and that of the fluxes themselves, in the existing or new developing technologies, the quantification of the thermophysicochemical properties of multicomponent slags and the effect of fluxes becomes indispensable. This paper reviews some of the work carried out by the author's group during the last ten years on the quantification of the thermophysicochemical properties of multicomponent slags and on the effect of fluxes in several smelting and converting processes in close relation to their individual characteristics. Several examples have been given in order to demonstrate the fact that when taken outside the context some fluxes can become in fact anti-fluxes.

Jan 1, 2003

By M Svartsjaern, D Saiang and K Mäkitaavola

The Kiirunavaara mine is a large-scale (28 Mt/a) iron ore mine located in northern Sweden. The mine is owned and operated by Luossavaara-Kiirunavaara Aktiebolag (LKAB) using sublevel caving (SLC). The SLC area underlies an open pit decommissioned in the 1950s, the current main SLC haulage level is situated at an depth of 1100 m. The main orebody dips 60 degrees to the east with a distinct boundary defining the hanging wall to the east and footwall to the west. Since the 1980s damage has been observed both in the footwall rock mass as well as on the footwall crest of the open pit. Recent investigations indicate that the underground footwall damage is primarily controlled by large-scale slope failure mechanisms. Structurally controlled near-vertical planar shear failures in the upper footwall appear to be driven or facilitated by a step-path like curved shear failure situated in a zone starting ca 250 m, and intersecting the SLC about 100 m above the active mining level. To confirm this failure evolution a pilot underground measuring system has been designed and installed to monitor the expected rock mass displacements indicated by numerical models based on the above mechanisms. The systems consists of 50 m time domain reflectometry (TDR) coaxial cables installed in the footwall both across and away from an estimated damage extent boundary to monitor shear movements along natural joint surfaces. The TDR installation is combined with long extensometers to facilitate differentiation between diffuse shear and rock mass normal expansion. Additionally, a low-tech system of tape extensometer lines are installed in drifts and stopes running perpendicular to the ore strike to monitor horizontal displacements in the infrastructure as the footwall ‘slope’ loses confinement during mining advance when the mined out areas are replaced by caved rock from the hanging wall.CITATION:Svartsjaern, M, Saiang, D and Mäkitaavola, K, 2016. Underground footwall monitoring at the sublevel caving mine – Kiirunavaara, Sweden, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 773–780 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Pedro Fuertes V.

El presente trabajo señala la mecanización en las operaciones de exploración, desarrollo, preparación y explotación en la industria minera a través de un programa de planeamiento y producción aplicado en el yacimiento Milpo. Para ello, se describe la estructura del yacimiento, el diseño de la mina, el ciclo de minado, transporte, servicios y administración del personal.

Nov 8, 1984

By Kennedy, Joseph E.

MANY things must be considered in coming to a decision as to what type of crushing and grinding equipment is to be used for preparing run-of-mine ore for concentration, amalgamation, flotation, or cyanidation. This paper is intended in no sense as a thorough discussion of these various factors, but rather contains a few observations based on a wide experience in the manufacture and application of milling machinery. One important governing factor is the tonnage to be dealt with. In large plants treating several thousands of tons in eight hours, a large jaw or gyratory crusher of substantial construction is standard equipment for reducing ore to 8 or 10 in. or finer. In open-pit work, using power shovels with 4- or 5-yd. dippers, a jaw crusher should have a receiving opening of 48 by 60 in., or 60 by 84 in., so that dynamite or hand sledging will not be required for breaking to a finer size before primary crushing. The coarsely broken ore is then conveyed by a belt to vibrating screens, the oversize from which is again conveyed by belts to secondary crushers having openings of 12 or 14 in., the product from which is conveyed to storage. From storage, the material goes to a finishing gyratory for reduction to 1/4 in. or finer.

Jan 1, 1936

By Kyle Murphy, John S. McCartney

This paper focuses on the seasonal thermo-mechanical response of two energy foundations installed at the new Denver Housing Authority Senior Living Facility in Denver, Colorado. The two drilled shaft foundations, which have diameters of 36 inches and depths of 45 ft and are end bearing in the Denver shale formation, include a closedloop series of polyethylene tubes through which fluid is circulated to exchange heat with the surrounding ground. The tubes within the foundations are coupled together with the conventional ground source heat pump system for the building and were installed to evaluate the heat exchange response of the foundations as well as any thermomechanical soil-structure interaction effects. A series of vibrating wire strain gages and thermistors were installed at different depths in the foundation to record the thermomechanical strain and temperature at different depths. Also, pipe-plug thermocouples are used to measure the inlet and outlet temperature of the heat exchanger fluid entering each of the foundations, which is necessary to evaluate the total heat exchange for the foundations and the efficiency of the heat pump. This paper will describe the energy foundation construction processes, the strain distribution and ambient temperature profiles during building construction and the seasonal strain and temperature distributions during heating and cooling of the building. The data indicates that typical heat exchange associated with heating and cooling operations leads to strains which are within acceptable limits, and that the foundations can provide a clear option for absorbing the base heating and cooling load for the building.

Jan 1, 2017

By S. Konetschnik, E. Dreyer, A. Filzwieser

"More intense furnace operations require effective cooling in order to achieve low refractory wear and good furnace lifetimes, making cooling technology an important aspect of furnace operations. However, the use of water - today’s standard cooling medium - has some disadvantages, as it can cause problems both during furnace start-up and operation, namely hydration problems, corrosion, and explosions. Apart from these aspects, the energy that is removed by extensive cooling cannot be recovered and is normally lost in the cooling towers.With METTOP’s new patented cooling technology it is possible to overcome the disadvantages of water by using an alternative cooling medium, namely ionic liquids (ILs). The main advantage of ILs is the fact that there is no risk of explosion should this liquid come in contact with molten metal. Furthermore, ILs can be used at higher temperatures than water - up to 200°C. This relatively high cooling medium temperature avoids hydration and corrosion problems and allows recovery of the energy by combining the ILTEC system and the organic Rankine Cycle (ORC) technology, for example.Due to the removal of the explosion risk, much higher safety standards can be achieved, particularly in critical areas such as tap-holes"

Jan 1, 2014

This paper presents the results of an investigation of the stability of the mass flow rates and average pellet size in the different streams of an industrial-scale balling circuit. The variables in this study include water content, drum speed and fresh feed rate. It was found that both the mass flow rates and pellet diameter are greatly disturbed when a change, positive or negative, in any of the variables takes place. For most of these disturbances to be damped don, a period of one hour or so is required. When a disturbance in the feed rate was made, the transient period extended to more than one and half hours (the duration of the experiment). It was observed that there is an interaction between the drum speed and moisture needed for producing an acceptable green ball product. The moisture content of the product pellets was found to be a function of the pellet size, with the larger pellets retaining a higher moisture content.

Jan 1, 1980

The term metamorphism as commonly used means any change in a rock in either form or composition, from whatever cause. By metasomatism, according to Lindgren, is meant a metamorphism that involves a change in the chemical composition of a rock by the addition or subtraction of substance. Certain types of metamorphism are due to the action of mineralizing solutions, and are closely connected with ore deposition; they form, therefore, valuable guides in the exploration for ore- deposits. Other types of metamorphism are due to regional processes, and are not connected with ore deposition. By dynamo-regional metamorphism is meant a primary alteration of rocks over large areas under conditions of pressure, flowage, and heat. This process produces schists and gneisses from either sediments or igneous rocks. It is thought that there is little migration of minerals or of elements in dynamo-regional metamorphism, and that the changes are due chiefly to recrystallization and rearrangement of original minerals in bands with their major axes oriented normal to the direction of greatest pressure. Under these conditions limestones are commonly altered to marble, and sandstones to quartzite, basic igneous rocks to greenstone or serpentine, while rocks of normal or acid com- position commonly yield the usual types of schist or gneiss. Dynamo-regional metamorphism, extending over large areas, has no connection with mineralizing processes, and is, therefore, no guide to ore deposits; while this process has certain features, such as characteristic mineral associations, in common with contact metamorphism, the results of the two processes may usually be distinguished without difficulty.

Jan 1, 1932

By Burnett C. C H

GEMNet, (Grade Estimation using Mapping Networks), is a grade/reserve estimation software system that uses the artificial intelligence technique known as neural networks to perform reserve estimates from both two- and three-dimensional data samples from a mineral deposit. The system is the result of research carried out over the past three years into the feasibility of using neural networks for reserve estimation at the AIMS Research Unit in the Department of Mineral Resources Engineering at the University of Nottingham. This paper describes the architecture of the GEMNet system including details of the neural network components of the system. The performance of the GEMNet system is then compared to several other widely used reserve estimation techniques on two reserve estimation examples. The results produced by the GEMNet system compare favourably with more conventional estimation techniques, but require fewer assumptions to be made about the form of the data used, and do not require the use of complex mathematical modelling.

Jan 1, 1995