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The placer mining industry of the West Coast region of the South Island is based largely around the production of alluvial gold, although other valuable minerals are also present. Since the first major discoveries in 1864-65, reported gold production has totalled around 264 t (8.5 Moz). During the past 10 years, annual production has totalled around 1460 kg (47,000 oz). It is anticipated that gold production over the next three years will continue at a level of 1400-1800 kg.   Annual gold production peaked during 1866 at approximately 17,170 kg (550,000 oz) and has not exceeded 100,000 oz since 1885. This reflects the ease with which gold was won from shallow, rich deposits that were present at many localities. Subsequently, there has been a general decline in the availability of this type of deposit, a trend that will continue in the future. This paper outlines the present state of placer mining in the West Coast region, gives some historical background to the industry and briefly predicts future trends.

Jan 1, 1997

The final criterion of the payability of gold production must necessarily be the cost per ounce. While the cost per ton or per cubic yard is a convenient comparative measure, and a necessary one for operating control, it is obviously insufficient as a means of judging whether or not, in a given set of circumstances, a gold production operation can be carried out economically.. An alternative method, which brings in the ton or cubic yard as a unit of measurement, is to determine what the cost per ton or per cubic yard is equivalent to, in terms of pennyweights or grains at the ruling price of gold. But this is really only another way of stating that the cost per unit of product is the ultimate measure of profit or loss, and not the cost per unit of input material.It is accordingly of interest to determine the cost per ounce of Australian gold production and to compare it with the cost of gold production in some other parts of the world which are important gold producers. The attached Appendix, which it, is believed comprises practically all Australian mines of any consequence (except Big Bell and the de Bernales group, for which. insufficient information is available), shows this information for financial years ending between 31st December, 1938, and 31st December, 1939, the production of gold dealt with being some 1,084,000 oz., or 66% of the total Australian production for 1939. For comparative purposes the cost of producing gold at representative mines in New Guinea, New Zealand, Fiji, Canada, India, West Africa and Rhodesia, and the average cost of production at the Rand mines, has also been included.It is obviously necessary in a study of this sort that the basis of the cost should be clearly set out and should be as nearly as possible uniform. The "cost" as calculated herein comprises the following items:

Jan 1, 1940

By Hubert E. Risser

Although, for about a half-century the percentage of coal production provided through strip mining has steadily increased, recent trends indicate that a peak in percentage (not tonnage) is being approached, principally because of the decline in economic adrantage enjoyed by strip mining compared to underground mining. Factors contributing to the decline are the decrease in the margin of advantage in manpower requirements held by strip mining; an increase in depth and volume of overhurden, requiring larger equipment and capital investment; increasing lack of reserve land blocks large enough to support extensive strip mining operations; more stringent legislation for reclamation of stripped land, with increasingly higher costs of such reclamation; and the increasing costs of land surface rights for strip mining. Already there has been a peak and suhsequent decline in relative importance of strip mining insome major Eastern coal-producing states; trends indicate that a peaking for the whole Eastern region is on the way. Although, in the West the pressures are less severe, they will, nevertheless, reduce to an increasing degree the advantage that strip mining has possessed. For about half a century, strip mining has been providing an ever-increasing share of total coal output in the United States, and in the past 30 years this share has grown from less than 8% to 33.7%, as shown in Fig. 1. Fig. 1 also shows that strip mining is gaining faster in the West than in the East. From 1961 to 1967, output from strip mines grew 63.6 million toqs, or 52.2%. Certainly there is nothing in such performance to indicate any peaking in the level of strip coal-mine production. But the fact is that, if not in actual tonnage, strip mining appears to be reaching its peak in relative importance, at least east of the Mississippi River. And the area east of the Mississippi provides 90.0% of the strip and 94.9% of the total coal production of the nation. The relative economic advantage which spurred strip mining's growth for a third of a century has been diminishing markedly in recent years. Fig. 2 shows evidence of this decline. From 1947 until 1961, strip tonnage output remained fairly stable, at the end of the period showing only a 12.5% decline. Meanwhile, underground coal production fell 44.5%. As the result of the greater decline in underground coal, strip coal in 1961 furnished 30.3% of the total coal produced, compared to only 22.1% in 1947. In the succeeding six years, however, underground coal output increased by 76.5 million tons, while strip output increased only 63.6 million. Further evidence of the strengthening of underground coal's relative position — or if you will, the weakening of strip coal's position — can be found in the major coal stripping states: Illinois, West Kentucky, Ohio, Pennsylvania, Indiana, and West Virginia, which in 1966 provided 80% of the nation's strip coal. Fig. 3 shows what has been happening in three states lying in the Appalachian field and in the total output of these three states. In the figure, the column height represents the output of coal mined by all methods. The number at the base of each column is the percentage mined by stripping. In Pennsylvania and Ohio, the percentage of strip mining increased between 1956 and 1961, but by 1966 had declined from the 1961 level. In West Virginia, a decline occurred during the first five years but was followed by a rise. In January 1968, Coal Age published an article listing the locations and capacities of new large mines in the planning and construction stages that would be operating by 1968-1971. The plans for West Virginia and Pennsylvania indicated all the new mines would be underground. Except to the extent they might replace existing under-

Jan 1, 1970

This paper evaluates the effect of longwall mining on a cluster of unconventional shale gas wells located in a district barrier pillar between a current longwall panel and the future panel north of the barrier pillar. A cluster of 19 unconventional shale gas wells have been drilled and 5 additional gas wells have been proposed in the barrier pillar. The closest gas well is 25.6 m (84 ft) to the current panel tailgate and 26.2 m (86 ft) to the tailgate of the future panel north of the barrier pillar. The rib-to-rib width of the barrier pillar is 57.9 m (190 ft). The distance between the two gas wells across the barrier pillar is 6.1 m (20 ft). The pillars in the current tailgate are on 22.9-m (75-ft) and 32.0-m (105-ft) centers, and the pillars in the tailgate of the panel north of the barrier will be on 22.9-m (75- ft) and 36.6-m (120-ft) centers. The two longwall panels adjacent to the barrier pillar are 475.5-m (1,560-ft) wide. The overburden depth at the shale gas well site is 321.6 m (1,055 ft). The wells have been installed in the barrier pillar, and the current district panel and subsequently the panel north of the barrier will be developed and retreated in the near future. The average min

Jan 7, 2020

By Virginia T. McLemore

The Gallinas Mountains are in northern Lincoln County and southern Torrance County, New Mexico, USA where a series of alkaline igneous bodies, including porphyritic latite, trachyte/syenite, andesite, and rhyolite laccoliths, flows, dikes, and plugs, have intruded Permian sedimentary rocks belonging to the Permian Abo, Yeso, and Glorieta Formations. A small amount of bastnaesite, a REE mineral, was recovered during processing for fluorite from the Gallinas Mountains. Four types of deposits are found in the Gallinas Mountains: epithermal REE-F veins, Cu-REE-F veins, REE-F breccia pipes and iron skarn deposits; all are associated with Tertiary alkaline to alkalic-calcic igneous rocks. Alteration includes brecciation, silicification, chloritization, and fenitization. District zonation is defined by Cu-REE-F (±Pb, Zn, Ag) veins that form center of the district, surrounded by REE-F veins. Carbonatites are inferred at depth by the presence of fenitization, carbonatization of the breccias, presence of REE and similarity of the intrusive rocks and mineralization to areas with known carbonatites.

May 1, 2011

By P. M. Daling

This report, sponsored by the U.S. Bureau of mines, presents the results of an examination of available safety assessment methods and their applicability to the mining industry. Standard safety analysis procedures were evaluated for relevance to the mining industry and mire operators' needs. The major safety concerns and needs of mine operators were identified through telephone contacts and a visit to a mine site. Safety assessment methods recommended for use by the mining Industry were also investigated for potential adaptability to a user-interactive computer system. Several methods were determined to be Immediately transferrable to the mining industry; these techniques are described in a user's handbook produced as part of this project. The handbook gives detailed instructions on appropriate application and utilization of these methods. Other techniques will require further development before they can be effectively transferred to the mining Industry. These methods, their advantages, disadvantages and resource requirements are described in the final project report. Recommended system safety analysis techniques facilitate an evaluation of total mine system safety and a determination of safety-related interactions among systems within a mine. The application of these methods to the mining industry could result In reductions in both the frequency and the consequences of mine accidents.

Jan 1, 1983

By Robert Linton

THE PURCHASE of silver by the United States Government under the provisions of the Pittman Act is practically completed. Producers of silver in this country will now have to market their silver in competition with the rest of the world. It therefore becomes of interest to study such data as are available and endeavor to obtain such suggestions as may be afforded therefrom as to the probable future market position of the metal. Conditions influencing the marketing of silver are numerous and complex. It is a commodity entering. into the arts and manufactures, and therefore influenced by the condition of various lines of business which make use of it; it is currency-being used by all countries for subsidiary coins and even as the founda-tion of the system by a very few; and it serves as a frequent basis for speculation. The various factors involved can easily set up so many cross-currents in the flow of the metal that predictions in regard to the market position of silver can never be safely made, although it may be possible to form some idea of prob-able trends over a sufficiently long period. Of course price is determined, as is the case with all commodities, by the inexorable workings of the law of supply and demand.

Jan 6, 1923

Several years ago, Hudco Industrial Products began experimenting with the idea of levitating a conveyor belt with a film of air, much like the puck on an air-hockey table. While conducting its research, the company found out that some Russian and Dutch companies attempted the concept during the 1970s. After studying those conveyors, Hudco determined that its design was better. The Hudco advanced air-supported conveyor consists of an air-tight plenum, or chamber, that runs the length of the belt. The topside of the plenum has a formed trough. It corresponds to the profile of conventional troughing rollers. Low-pressure air is provided to the sealed plenum from a low horsepower blower. This pressurized air is metered and released through the central portion of the trough and reacts against the underside of the belt. The differential pressure between the top and bottom surfaces creates the lift to support the loaded belt. Airtight covers are installed to seal the transported materials in the plenum trough.

Jan 1, 2002

By W. Mbhalati

"Conzal Mine was not meeting production targets in 2013, and it was established that this was caused by the inability of the load haul dump machines (LHDs) to tram the required tonnages. An investigation of the LHD productivity was therefore conducted to identify the inhibiting factors. This was accomplished by carrying out a literature review on LHD operations to gain in-depth knowledge and conducting observations in the working environment. The relevant information and data on the LHD type used at Conzal was also acquired.The major inhibitor was found to be excessively long tramming distances in all the sections of the mine. The one-way tramming distances were all significantly greater than the 90 m set in the mine’s code of practice (COP), with the Main Shafts section having the longest average one-way tramming distance of 260 m. The other inhibitor was LHD utilization, which in 2013 was only 47% against a target of 70%. Simulation of the LHD operation, taking these two factors into account, showed that production could be increased by more than 100%. As a result, it was recommended that conveyor belts should be extended regularly in order to keep tramming distances within the recommended one-way distance of 90 m. In addition, utilization can be improved by minimizing employee absenteeism as well as by modifying the travelling routes such that LHDs do not encounter unnecessary delays.Paper written on project work carried out in partial fulfilment of BSc. (Mining Engineering)"

Jan 1, 2015

The Hyde Macraes Shear Zone (HMSZ) is an extensive low angle semibrittle mineralised structure in the Otago Schist Belt, New Zealand. The shear zone is located on the lower limb of a late metamorphic recumbent fold. Structural observations suggests that the shear zone initiated as a high strain mylonite zone and transgressed the ductile/brittle boundary (D4) later in its development. A surge zone at Round Hill is bounded to the south by a NE-SW striking lateral ramp which displaces the hanging wall shear (HWS) by 50 m. Oblique strike slip displacement during surge zone propagation created space for deposition of the sheeted vein complex or stockwork. Quartz recrystallisation in stockwork veins suggests that the veins were deformed in a ductile manner and implies that surge zone propagation may have occurred during late D3 deformation. A macroantiform was produced during D3/D4 shortening below the HWS. Over tightening of the antiform hinge created SW and NE-dipping ramp thrusts. Continued strike slip displacement along the lateral ramp rotated the antiform and associated ramps into a south plunging drag fold. Post-mineralisation (D5) structures include NE-dipping nonna! faults below the HWS and SW-dipping low angle imbricate thrusts above the HWS. The development of these structures was kinematically compatible with normal movement on the HMSZ and is related to mid Cretaceous break up of Gondwanaland in the SW Pacific.

Jan 1, 1992

By Chen-Luh Lin, Jan D. Miller, Sindhoora Puvvada

The depletion of good-quality phosphate resources, coupled by a need to supply acceptable products at a rapid rate, while meeting the specifications of fertilizer chemical plants, is of significant concern to the phosphate industry, particularly the production of concentrates with tolerable dolomite content. Tremendous efforts have been made in the past to develop an efficient and economical process that can effectively reject dolomite. However, dolomite removal continues to plague the phosphate industry due to several process-specific challenges being encountered with various beneficiation technologies. In this regard, detailed characterization of phosphate reserves is crucial to understand textural limitations and help design appropriate strategies to achieve quality products. In this paper, the development of procedures to establish dolomite rejection/francolite recovery curves for gravity preconcentration of pebble phosphate from Central Florida is described using high-speed X-ray computed tomography (HSXCT). The developed procedure is illustrated with the analysis of high MgO pebble phosphate samples (10.39 mm × 1 mm) received from South Pasture and Four Corners locations operated by the Mosaic company. The rejection/recovery curves were calculated for each sample for five different particle size classes to observe the trend in rejection/recovery with variation in particle size. In order to evaluate the reliability of the HSXCT data, analysis using the high-resolution X-ray computed tomography (HRXCT) technique was performed on one particular sample (FC-3-1). Finally, to assess the separation efficiency, the HSXCT and HRXCT rejection/recovery curves obtained were compared to experimental gravity preconcentration results reported in the literature. In this way, liberation limitations for gravity preconcentration in the processing of pebble phosphate have been established based on X-ray computed tomography analysis.

By J. H. Adkins

The goal of this program was to produce a set of baseline health and safety training materials that could be used by the metal/nonmetal mining industry to reduce injuries and to comply with federal training requirements. The materials developed are arranged in a two level outline format. The first level provides the title, course goals, background and topical outline while the second level provides a detailed outline of the course content. Visuals, designed to portray miners in a positive, attractive fashion, were done in simple line drawing so they would reproduce for handouts without loss of quality. Each of the required units in the Baseline Guides have one or more self-checks. These are designed to be suggestive of evaluation techniques the users can develop for themselves. An instructors guide and a mining terms glossary are included. In a second phase the program developed performance based training guides for Annual Retraining and Experienced New Hires in the Underground Salt Industry.

Jan 1, 1983

By Jerry Gagnon, Matt Burr, Dave Evans, Timothy Ellis, Davies Kakengela, Abbas Mirza, Larry Webb, François Leclercq, Andrew Johnston

Lead-based alloys are the primary anodes used in electrowinning from sulphate-based aqueous systems. Lead anode technology has evolved over the years, migrating from pure lead and lead-antimonial alloys to the present day lead-calcium-tin alloys for copper electrowinning and lead-silver alloys for zinc electrowinning. It has also migrated from cast to rolled microstructures in search of improved mechanical properties and higher corrosion resistance. Although great strides have been made in the development of new alloys and production processes, the industry still has unresolved issues related to untimely corrosion which limits anode life and may lead to higher contaminant levels in the metal being produced. Lead anodes corrode because of the difference in the chemical/electrochemical potential across the microstructural features of an anode. Given a very high purity material, we find that the grain boundary areas corrode significantly faster than the rest of the grain. The desire to minimize grain boundary corrosion by a balance of alloying element selection and microstructural design allows the grain boundary area to be engineered. However, operational issues can lead to unexpected corrosion behaviours which we will discuss moving forward. The comments in this work, though directed toward copper electrowinning, can be extended to similar phenomena in other metals electrowon from sulphate media (i.e., zinc, nickel, cobalt, manganese). The lifecycle of electrowinning anodes is dependent upon electrowinning tankhouse operating conditions and maintenance of the anodes, including cleaning and straightening. This paper will focus on the operational aspects of maximizing the utilization of lead electrowinning anodes.

Jan 1, 2015

By J. H. Zietsman, M. W. Erwee, P. J. A. Bezuidenhout, Q. G. Reynolds

"Pyrometallurgical furnaces are tapped through tap-holes that are opened with drills and oxygen lances. The lance is often used on its own or as the last step of opening the tap-hole. Interaction of oxygen with molten material inside the tap-hole can occur, and is a phenomenon that is not well understood. As part of a study that focuses on the effect of lancing on flow inside and around the furnace tap-hole, a cold-model validation was done. The validation study focuses on validating the MULTIPHASEINTERFOAM multiphase flow solver in OpenFOAM® for the problem involved. The sensitivity of the model to different materials properties (viscosity and density in particular) is presented with both cold models and the results from flow simulations in OpenFOAM®. IntroductionMany pyrometallurgical operations are carried out in furnaces where molten material accumulates continuously. Once enough material has accumulated and is ready to be removed from the furnace, material is tapped through one or more tap-holes in the furnace. Tap-holes differ significantly in both geometry and materials of construction, depending on the process involved – examples of different types of tap-hole configurations can be found in, for example, Nelson and Hundermark (2014). Tapholes all share one common feature: they are high, wear areas of the furnace. Molten material at high temperature flows through these areas, after which the tap-hole is sealed, usually using tap-hole clay. The purpose of the tap-hole clay is to harden inside the tap-hole and seal it until the next tap.Once ready to tap, a pneumatic drill and/or oxygen lance is used to open the tap-hole. The extent of lancing a furnace tap-hole depends strongly on the type of furnace. In, for example, many blast furnace operations lancing is limited as much as possible, and done only if drilling was not effective. In other operations, such as on small-scale pilot furnaces with short tap-holes, only lancing is used to open the tap-hole."

Jun 1, 2019

By T de Wit, S Meyer

The location of seismic events in mines is traditionally calculated based on the arrival times of P- and S-waves for a given velocity model (homogeneous or heterogeneous). This technique is successful when the sources of seismic events are sudden and localised (eg episodes of fracturing in solid rock or dynamic slip along a plane of weakness) and thus the radiated seismic waves have clear arrivals. In massive mining operations such as block caves, strong seismic signals often originate from the movement of loose rocks on the perimeter of the fracture zone. These signals are easily recordable but do not contain easily identifiable direct P- and S-waves, making the estimation of location through traditional methods more complicated. This problem has been approached by using a ‘brightness’ location method that estimates the origin of seismic waves based on travel times of envelopes of seismic energy. This tool is extended to be applicable in a heterogeneous velocity environment that now accounts for the presence of a cave or other strong velocity perturbations. The suggested method is particularly important when caving occurs in low-stress environments (eg close to the surface).CITATION:Meyer, S and de Wit, T, 2016. Location of seismic events associated with caving using brightness method, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 225–236 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

The flolation behaviour of some Australian uranium ores was investigated. Although uraninite and pitchblend float readily with fatty acids, selective concentration to produce an economically discardable tailing has not yet been achieved. This is attributed to the presence in the ores of a quantity of uranium mineral in finely dispersed form which is very difficult to liberate. For some of the ores, at least, the proportion of this material decreases with increase in head assay.Flotation may be a useful concentrating method for some Australian ores if uranium oxide is to be sold in a free competitive market.

Jan 1, 1967

By Jorge Meza

El presente texto señala la aplicación del sistema de gestión de demanda y consumo de energía eléctrica en la fundición de Southern Perú. El sistema está compuesto por un módulo predictor de demanda eléctrica y un módulo de simulación del sistema eléctrico de la planta. El primero, se construyó utilizando redes neuronales con algoritmos de aprendizaje backpropagation, capaz de pronosticar la evolución horaria de la demanda eléctrica con un porcentaje de error cercano. Mientras que el segundo está basado en técnicas de estimación paramétrica, redes neuronales y ecuaciones matemáticas obtenidas por regresión estadística, que simula el comportamiento del sistema de energía eléctrica de la fundición. En ese sentido, los módulos facilitan una adecuada planificación, ya que permiten conocer el comportamiento de la demanda horaria y los patrones de consumo de la planta, incluyendo los componentes de la facturación. Así como las deficiencias energéticas y oportunidades de mejora, sobre la base del análisis de la información acerca de los equipos, procesos y planes de producción, así como programas de mantenimiento.

Sep 24, 2008

By Göran Bäckblom

The Swedish mining companies LKAB and Boliden, the equipment supplier Atlas Copco, the general contractor NCC and the specialist company Reflex joined forces in 2005 to advance the field of rock technology for the purpose of mining and underground construction. The creation of the company Rock Tech Centre is part of the strategy developed by the Swedish mining industry to strengthen co-operation with industry, academia and society. This paper outlines the current R&D strategies developed for the industry in general, discusses what focus areas are selected and provides some details on the current RTC project portfolio, especially faster and better drifting.

May 1, 2006

By S. Narasimha Rao

Significant amounts of lateral load may act on pile foundations supporting structures such as transmission line towers, tall structures, bridge abutments, offshore platforms, quay wails, harbour structures and anchorages for water front structures. There were several theoretical and experimental studies conducted on laterally loaded piles in clays to determine ultimate lateral capacity and deflections under working loads. Under a lateral load, a pile deflects in the direction of load application and the soil in front of the pile offers resistance to this movement. The ultimate lateral resistance of a pile can be estimated considering the statics of the pile for a known distribution of soil resistance with depth. In this paper, considering the contributions from both lateral shear drag and frontal passive earth pressure, a method has been proposed to estimate the ultimate lateral capacity of rigid piles in clays. The lateral shear drag has been estimated in terms of adhesion and shape factor. A few load tests were conducted on model piles subjected to lateral loading and these experimental values are used in verifying the proposed method. The reported results obtained from both model tests and field tests were used in support of the predictions made. In all the cases, there is a good agreement between the predicted and measured capacities.

Jan 1, 1996

By Thomas M. Barczak

The 1990s brought an unprecedented increase in the development of innovative technologies to provide more effective and easier-to-install roof support in underground mines. To facilitate the application of these technologies in improving mine safety, the National Institute for Occupational Safety and Health (NIOSH) developed the Support Technology Optimization Program (STOP). STOP is a Windows-based software program that provides mine operators with a simple and practical tool to make engineering decisions about the selection and placement of these various roof support technologies. The program includes a complete database of the support characteristics and loading profiles obtained through safety performance testing of these supports at the NIOSH Safety Structures Testing Laboratory. A support design criterion in the form of the required support load density at a specified convergence can be established from four options: (1) a database of measured ground reaction obtained from various mines or ground behavior information input by the user,(2) load requirements based on a detached roof block or rock failure height, (3) criteria based on the current roof support system, and/or (4) arbitrary criteria set by the user. Using these design criteria, the program will determine the installation requirements for a particular support technology that will provide the necessary support load density and convergence control. Optimization routines are also available to determine the most efficient support design for a user-specified support installation. In addition to these performance measures, STOP can be used to compare material handling requirements and installation costs. Comparisons among the various support technologies are easily made, including a graphical analysis of relevant support parameters. This paper describes STOP and its application to optimizing standing secondary roof support systems.

Jan 10, 2000