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By Thomas J. Kuli, Tim Rape

When a fan or blower breaks down or becomes worn, customers have two choices. They can replace it or they can have it repaired. In the past, replacement was the preferred option, especially when the equipment was severely damaged or worn. Now, however, customers are discovering the benefits of repairing or rebuilding. Even when the cost of repair is more than 60 percent of the cost of a new fan, customers are choosing the repair option. The cost savings can range from 20 percent to 80 percent. In many cases, the quality of the repaired part or component will exceed the quality of the original. This is because repair engineers have an advantage over the original designers. They can see how the existing fan performed — or failed to perform — in a specific application.

Jan 1, 2005

By J. D. Morgan

Demand for nonfuel minerals depends on the overall state of the economy, which steadily improved each quarter in 1984. New housing starts rose to 1.8 million units. Automakers turned out about 15% more cars (7.8 million) and 30% more trucks (3.1 million) than in 1983. Nevertheless, many domestic mineral operations experienced difficulties in 1984. This resulted from import competition greater use of newer engineered materials, emphasis on multi-unit housing and downsizing of motor vehicles. About 15% of our energy was imported. This in cluded $36 billion worth of crude oil and $22 billion in refined products This added significantly to the overall merchandise trade deficit of $12; billion. On the bright side for mining, coal production rose 14% to 810 Mt (890 mil lion st). Three-fourths o: the coal was burned to generate electricity and more than half of our electricity was derived from coal-burning plants. With the exception of a few large-bulk, low-value raw minerals, most minerals move relatively freely in world trade. The strong dollar encouraged imports and made exporting more difficult. Consequently, our nonfuel minerals trade deficit rose 60% to $19 billion, reflecting imports of $39 billion and exports of $20 billion. There were increased pressures from some major segments of the minerals industry for some form of import protection. But President Reagan said, "Our goal is a system of free and fair trade in goods, services, and capital. We will work toward this goal through both bilateral and multilateral trading agreements." The US minerals industry consists of domestic mines, concentrators, smelters, refineries, mineral manufacturing plants, and recyclers. It also includes many wholly- or partially-owned operations in many parts of the world, providing employment and income for US citizens and others as well. Compared with 1983, the value of US raw nonfuel mineral output rose 8%, to $23 billion. The $253 billion worth of goods processed from this crude mineral output was a 14% increase. Major Metals Raw steel production - a major indicator of both material use and mineral production-rose 10%, to 84 Mt (93 million st). This stimulated a 36% rise in domestic iron ore production, to 52 Mt (57 million st), about 98% pelletized. Iron ore imports rose 44%, to 14 Mt (15 million st). Despite the increase of steel production, output remained well below levels of just a few years ago. For example, 1984 production was still 23% less than in 1981. Raw steelmaking capacity remained steady at 122 Mt (135 million st). The industry continued to cite steel imports as a major reason for low domestic capacity. In December, pacts with seven leading steel exporting nations were announced. This is an effort to reduce import penetration to about 18.5% of the domestic market. Domestic producers of bulk ferroalloys of chromium, manganese, and silicon operated at about 50% capacity. The US mined no manganese or chromium. Only a small quantity of ferronickel was produced from domestic laterite mining in Oregon. Molybdenum production, at 45 kt (49,500 st), rose threefold. Mine shipments of tungsten, another mineral tied to steel

Jan 5, 1985

[COUNCIL FOR 1991/92 President R.D. Beck President Elect JP. Hoffman Vice Presidents Senior Junior Dr H. Scott-Russell J.A. Cruise Immediate Past President Honorary Treasurer H.G. Mosenthal J.A. Cruise Members of Council Dr N.A. Barcza G.A. Brown B.R. Broekman Prof. RJ. Dippenaar B.R. Fleetwood* J.S. Freer P.R. Janisch P.J. Knottenbelt Dr J. Lurie R.P. Mohring *Co-opted K.C. Owen P.D.K. Robinson D.A.J. Ross-Watt P. Smith K.A. van Gessel DJ. van Niekerk P. van Schaardenburgh* CJ.C.J. van Vuuren* P.M.T. White]

Jan 1, 1992

By J. Tanner Blackburn, James R. Gingery, Lisheng Shao

Rigid inclusions consist of grout columns installed using displacement auger or vibrated tooling. The columns are typically installed in an array to provide support for footings, mats, or embankments. Due to the relative small column diameter and low replacement ratio, the surrounding soils typically have minimal densification or improvement. A gravel load transfer platform is commonly used above the rigid inclusion head to distribute stresses more broadly to the supported structure. The axial stiffness and geotechnical engineering mechanics of rigid inclusion design are similar to those of deep foundation systems, but they are typically only lightly- or un-reinforced and are not structurally connected to the above-grade structure. The popularity of rigid inclusions is increasing in the Western U.S., where many urban areas are subject to moderate to high seismic hazard levels. However, the performance of rigid inclusions under seismic loading is poorly understood, and seldom addressed in current designs. The elements are brittle, with limited or no ductility and relatively low moment capacity, and therefore may be prone to damage under seismic loading. Three modes of seismic loading should be considered: inertial loading from the structure, kinematic loading from vertically propagating shear waves, and kinematic loading from ground failure- related permanent ground deformation. This paper focuses on the first two modes. A simplified procedure for evaluating kinematic and inertial loading of rigid inclusions is described, and its use is illustrated through application to a site in Southern California. The results show that moderate to severe kinematic loading can generate plastic hinges in the rigid inclusions. Engineering consequences of this hinging could include settlement or bearing failure. INTRODUCTION In this paper the term ‘rigid inclusion’ (RI) refers to grout or grouted aggregate columns that are installed using either drilled or vibration displacement techniques. They are commonly installed in arrays to support vertical loads from footings, mats, or embankments. RIs are not structurally connected to footings they support. Rather, it is typical for a dense gravel load transfer platform (LTP) to be installed as a cushion between the RI head and supported footing or new fill. In cases of RI support of fill embankments, the LTP may be reinforced with horizontal layers of geogrid.

Jan 1, 2018

By Robert A. Cummings

A rock mass classification system has been developed for support estimation in mines using caving methods. The developed system (MBR System) accepts readily-obtainable geotechnical properties, and mining geometry, to develop a rating that permits recommendations for drift support in block caving mines. The data base includes major active United States caving mines. The method is intended to be used for planning and estimating purposes and for preliminary support design. The Manual explains the organization and nature of the MBR System, its derivations, details of required input data, methods for assessing the data and for developing rock mass ratings, and techniques for selecting the most appropriate mine support recognizing mine requirements and desired stability. A worked example is provided.

Jan 1, 1984

Bio-Oxidation of Arsenic and Stibium Bearing Gold Ores Bio-oxidation of arsenic and stibium bearing gold ores with acidithiobacillus ferrooxidans was studied. The preoxidation results show that the best bio-oxidation technical parameters are the initial pH in the range of 1.8 ~ 2.0, particle sizes under 0.074 mm, temperature in the range of 25¦C ~ 30¦C and rotating speed of the orbital incubator in 100 rpm ~ 160 rpm. The leaching results show that If the ore, of which contain 10.37 per cent arsenic and 36.81 per cent stibium, is not bio-oxidised, gold leaching is only about 41 per cent, after 8 days oxidised, the result is about 76.55 per cent, which improved about 35.62 points. The relationship between gold leaching and arsenic oxidation is direct proportion, furthermore, it needs only partly oxidise and higher gold leaching could be get, for example, gold leaching is over 90 per cent when asenic oxidation is 60 per cent. The results will provide theoretical and technological supports of bio-oxidation arsenopyrite for pretreating refractory gold ores.

Sep 13, 2010

By Maxwell Gensamer

Jan 1, 1960

By B. Schoevaerts

The ever-increasing depth of mineral extraction presents a challenging environment for hard-rock underground mines. High in situ stresses and associated seismicity with potential rockburst hazards are the major decisive factors contributing to the choice of a ground support regime. Conventional ground support systems, designed primarily for static loads, are not always capable of providing safe working conditions for underground personnel in seismically active mines. Systems specifically developed to resist dynamic loading and allowing for larger deformations are therefore preferred alternatives. High-tensile chain-link mesh has a proven record of successful use in open cut operations in various rockfall barrier installations due to its high energy absorption capacity. It has also been used in underground operations in various parts of the world. Its application in South African underground mining, however, is limited due to the high labour intensity. This paper describes a method of mechanized installation of a chain-link mesh as evaluation at Gold Fields' South Deep Gold mine situated some 45 km south-west of Johannesburg. A purpose-built mechanized roll mesh handler, developed in Australia, was used in this trial. The handler is compatible with all standard multi-boom underground drill rigs and is operated utilizing the hydraulic circuit normally used for the feed arrangement. A number of key performance indicators have been specified as success criteria by Gold Fields: ? A 30% faster installation compared to the conventional methodology ? The mesh should sustain any blast damage when applied to the blasting face ? No unravelling of the mesh when cut ? No failure of mesh under normal conditions ? Reliability of the MESHA® installation handler (availability >90% ? Compatibility of the MESHA® installation handler with AC 282 boomers. Although the energy-absorbing mesh combined with yielding rockbolts is a ground support system of choice for rockburst-prone conditions, the operational upsides recognized during the trial imply that this product can also be competitively used in less demanding ground conditions where weld mesh or shotcrete are customarily used as a primary surface support.

Jan 1, 2012

By Benoît Demers

Dans ses opérations de traitement de concentré de zinc, l?usine de Zinc Électrolytique du Canada à Valleyfield génère un résidu minier appelé « jarosite ». Jusqu?en 1998, le jarosite était transporté hydrauliquement dans des bassins construits en argile. Le jarosite sédimenté possède une consistance très molle (impossible de circuler à pied sur le résidu consolidé) avec une eau interstitielle acide contenant des teneurs élevées en métaux. Ces caractéristiques particulières au jarosite rendaient très coûteuses la construction et la fermeture des bassins de résidus. En 1998, Zinc Électrolytique du Canada a implanté un nouveau procédé, développé chez Noranda, dont le principal objectif était de stabiliser chimiquement et physiquement le jarosite. Un nouveau concept de déposition a été élaboré pour le nouveau résidu minier appelé « jarofix ». Les grandes caractéristiques du nouveau procédé et du concept de déposition sont : ? Le jarosite est lavé et déshydraté à l?usine avec un système de filtre; ? De la chaux, du ciment et de l?eau sont ajoutés pour former le jarofix; ? Le jarofix est transporté par camions jusqu?à l?aire d?accumulation; ? À l?aire d?accumulation, le résidu est géré selon un concept d?empilement. L?élaboration du concept d?empilement et de l?aire d?accumulation devait tenir compte des caractéristiques de déposition du jarofix, de sa résistance à l?érosion hydrique et éolienne, de la gestion de l?eau de ruissellement, de la faisabilité de construire les digues de ceinture en utilisant du jarofix durci et de la nécessité de restaurer progressivement l?aire d?accumulation. Le déchargement du jarofix se fait à partir d?une rampe qui progresse avec une pente ascendante pour développer un front de déversement de plus en plus haut. La hauteur du tas de jarofix atteindra 30 m au centre du site. L?aménagement initial de 1998 a inclut une digue d?amorce de 3 m de hauteur, une rampe de déversement de 8 m de hauteur et un bassin pour la gestion de l?eau de ruissellement. Les propriétés du jarofix consolidé dans l?aire d?accumulation sont déterminées annuellement. Le jarofix durci possède la consistance et la résistance d?une argile très raide. Sa conductivité hydraulique est similaire à celle d?un silt et il résiste bien à l?érosion éolienne. Après trois années de déposition, la température du jarofix au milieu du dépôt demeure élevée. Le jarofix durci est facile à excaver et à compacter, ce qui en fait un excellent matériau pour la construction des digues de ceinture en périphérie du site.

Nov 1, 2002

By J. C. Potvin

Although the occurrence of deposits of titanium minerals on Kenya’s present day beaches and adjacent dune systems has been well documented, the potential for older formations to host economically viable deposits had not been recognised until recently. The Magarini sands formation in Kenya has been found to contain deposits of ilmenite, rutile and zircon in quantities and grades that have the potential to be commercially exploited. Since 1995, Tiomin Resources Inc. has explored these deposits and has identified one deposit, the Kwale project, as being able to support the development of a mine producing some 300,000 tpa ilmenite, 75,000 tpa rutile and 37,000 tpa zircon. Tiomin plans to start production by late 2002. Construction of a US$137 million operation is set to commence in the first half of 2001.

Jan 1, 2001

By G. I. Mathieu, R. W. Bruce

Flotation schemes for the separation of molybdenite from other minerals are based on utilizing the Inherent hydrophobicity of molygdenite (Fuerstenau1). This natural floatability was attributed to the crystalline structure of molybdenite by Gaudin et al.2 who suggested that any surface formed by the rupture of van der Wall's bonds should be hydrophobic and, therefore, naturally floatable. Other authors argued that "natural floatability" is dependent of adsorption of hydrocarbon ions and/or molecu1es on the surface of the minerals. This theory, albeit-c questioned 1,2 has long been recognized in actual practice of molybdenite flotation as the latter in carried out with hydrocarbons, such as fuel oil, kerosene and stove oil. Although conferring ready floatability to molybdenite, these presents generally have little effect on other sulphides and silicates. However, talc is a noteworthy exception because of its innate floatability4. Not withstanding the reason for this behavior which has also been attributed to crystal structure2 its end results as in the case of molybdenite is an immediate flotation response to frothing oils arid kerosene, as was observed by Baranovski5, Sutherland and Wark6.

Jan 1, 1974

By F. M. C. C. Vieira

The DEEPMINE Research Programme sought to develop the technology and competence to mine gold safely and profitably at depths of 3 to 5 km. Among the many issues addressed was the stability and support of rockpasses at ultra-depth. It was found that high virgin and mining-induced stresses could cause the walls of rockpasses to spall, leading to the deterioration and failure. A comprehensive programme of numerical modelling was conducted to investigate alternative mining layouts and sequences to ameliorate the problem.

Jan 1, 2005

The phosphorus content of the banded iron formation (BIF) and of the associated iron ore deposits in the north west of Western Australia is known to vary widely, a fact which has considerable econ~mic significance. Trendall and Blockley (1970) have described the variety of textural appearances of apatite in the Hamersley Group BlF, and suggest that apatite may account for the entire phosphorus content of the unaltered BIF.A preliminary investigation using an M.A.C. electron microprobe analyser has shown that, at least in some iron ores and in partially enriched BIF and associated shales, the phosphorus occurrence is more complicated than this. A suite of samples was examined from one location which covered the entire Dales Gorge Member and some adjoining macrobands in the Mt. McRae shale, together with samples selected for their high phosphorus content, degree of ore enrichment, and position relative to the enrichment zone. Calcium apatite was not observed in any sample of ore from this sequence, despite its ubiquitous occurrence in the BIF. Silicate mineralogy in the enriched regions also differs from that in the BIF, but this change has not yet been studied in detail.The phosphorus content of goethite in one orebody is often high and appears to be in solid solution in the goethite structure. It shows little or no variability on a micro-scale within a grain, except where theremay be a zoned enrichment near boundaries and solution channels. There is also a limited solubility of phosphorus in hematite (the maximum observed by the author is 0·1 per cent P); but where the hematite is martitic (after magnetite) its phosphorus content is always low or zero. In some bands, martitic hematite has been hydrated to goethite, and this also has a very low phosphorus content. Phosphorus was not found in the silica or silicates in the ore, and even when iron enrichment is just beginning, a limited suite of samples from the BIF suggests that the phosphorus content of the chert microbands is almost entirely in the microscopic goethite nuclei (after riebeckite) scattered throughout the chert. The ability of goethite and hematite to accept phosphorus...

Jan 1, 1973

By K. Najim, D. Hodouin

"The raw ores which are processed in mineral processing plants exhibit very strong variations of their physical and chemical properties. As a consequence, the performances of the comminution and separation processes vary greatly from time to time. Model-based control strategies improve the performance of the plant; however, they require some form of adaptation to cope with the variations of the are properties.This paper deals with the use of adaptive techniques for the control of mineral processes. It begins with a survey on adaptive control algorithms including parameters estimation aspects. Then several examples dealing with crushing, rod, ball, autogenous and semi-autogenous grinding, flotation , drying and calcination processes are reviewed.IntroductionThe operation of the various processes of mineral processing plants (crushing, grinding, flotation, dewatering, etc.) is generally controlled using empirically tuned regulators of constant structure, such as PID controllers. To improve the operation performance, mineral processors try to implement specifically designed controllers, i.e. controllers based on plant dynamic models. Most of the time, these techniques improve the control of the mineral processing installations. However, modelling is a complex procedure because of the problems of measurement and data management, specific to this industry, and because of the variations of the model parameters. In this context model-based control strategies do not always bring the expected improvements or are sometimes discarded and replaced by more conventional techniques .The sources of variation of the dynamic behaviour of mineral processing systems can be classified into three categories: (I) the inherent changes of the raw ore properties (composition, grindability, mineralogical texture, etc.); (2) the process tuning modifications (grinding media loads, number of hydrocyclones, slurry level in flotation cells, agitation speeds, etc.); (3) the feedrate variation of the ore, water, chemical reagents, etc. All these factors change the fundamental properties of the process dynamics such as the grinding or flotation rates and the residence time in the equipment. The simplified linear models which are used to describe the process dynamics are not able to track the complex behaviour of the mineral processing systems when the amplitude of the sources of variation are too large. The mismatch between the model and the plant behaviour is then frequently a cause of model-based controller failures."

Jan 1, 1992

By R. Lombard

"Water is a very important component in the production process at underground coal mines. Current unfavourable economic conditions have forced the coal mining industry to identify and address every possible bottleneck preventing optimal production. An increase in water-related downtime was identified as one of the bottlenecks at Goedehoop Colliery’s Vlaklaagte Shaft. The purpose of this project was to identify the various causes that contributed to the high downtime (501 hours in 2013, which led to a potential profit loss of R12.9 million) and to suggest possible solutions.After a thorough investigation the main causes of water-related downtime were identified as low water pressure and low water flow caused by pipe leakages and bursts. The main root cause for the low water flow and pressure was identified as being the low pressure resistance (1600kPa) of the thin-walled galvanized steel pipes used in the underground inbye water reticulation system. The pipes were selected according to the previous 1000 kPa pressure requirement for the continuous miner. However, the pressure requirement changed to 1500 kPa, which resulted in the pipes being exposed to much higher pressures than designed for.The water reticulation system was reviewed and current and future underground pipe layout and water requirements were determined for the shaft. The time frame in which the water consumption would be the highest was determined to be between 1 January 2014 and 7 September2014. Machine and sprayer specifications were used to determine theater consumption at the shaft. Three different solutions were considered to solve the water-related downtime problem and to ensure the efficient supply of water to the newly open sections. Permanent underground concrete dams, semi-mobile dams, or new pipe columns with a higher pressure resistance of 3200 kPa were considered. A trade-off study (taking into consideration cost, time to completion and ease of implementation, maintenance requirements, safety, and flexibility) was completed to determine which of these solutions would be most viable.Paper written on project work carried out in partial fulfilment of B. Eng. (Mining Engineering)"

Jan 1, 2015

Following a short review of selected literature, a back analysis of stress measurements of stress regeneration in a closed mini-longwall is shown. The agreement is good, lending confidence to the parameters used in the proposed numerical model. Foundation yielding was modelled in the absence of total stope closure. A ?Prandtl? wedge was formed, coinciding with the yield point of the pillar/foundation system. Some theoretical work is used as a starting point for the formulation of a new design methodology for strike or dip stabilizing pillar/foundation systems in deep level goldmines. The existing guideline for the stability of foundations (APS< 2.5UCS) is critically examined. Finally, the advantages of the new approach, and the work required to substantiate the proposed new design methodology, are outlined.

Jan 1, 1998

By William J. Campbell

Three types of X-ray analytical instrumentation were compared for applications in the secondary brass and bronze industry. The instruments were a conventional X-ray spectrograph, a portable X-ray spectrograph, and a radioiso-topic X-ray analyzer using balanced filters. The following two general applications were considered: Rapid identification for sorting scrap metals and quantitative analyses to provide guidance in the melting and casting of alloys. Twenty-three analyzed copper-base alloys were used as standards. Although the alloys varied widely in composition, matrix correction procedures were not necessary except for copper. The conventional X-ray spectrograph provides positive identification of the alloys and quantitative values for the six elements investigated--aluminum, copper, iron, lead, tin, and zinc. Equivalent results were obtained with the portable X-ray spectrograph for those elements whose characteristic X-rays are in the wavelength range of the instrument. The radioisotopic X-ray analyzer distinguishes certain groups of alloys and provides quantitative determinations for copper, lead, tin, and zinc. The sensitivity of the analyzer was marginal for the determination of small concentrations of elements of atomic number 26 or lower.

Jan 1, 1972

By John F. Gamble

Amphiboles are hydrated mineral silicates five of which occur in asbestiform habits as asbestos grunerite (amosite) asbestos, riebeckite (crocidolite) asbestos, anthophyllite asbestos, tremolite asbestos and actinolite asbestos] and non-asbestiform habits (grunerite, riebeckite, anthophyllite, tremolite and actinolite). The asbestiform varieties are characterized by long, thin fibers while non-asbestiform varieties such as cleavage fragments form short fibers with larger widths. The U.S. regulatory method for counting asbestos fibers (aspect ratio [>]3:1, length [>]5 µm) does not distinguish between asbestos and cleavage fragments. The method biases toward increased counts of non-asbestiform cleavage fragments compared to long, thin asbestos fibers. One consequence of this regulatory approach is that workers can be erroneously classified as exposed to concentrations of asbestos (asbestiform amphiboles) above the U.S. 0.1 f/mL exposure standard when in fact they are not exposed to asbestos at all but non-asbestiform amphibole cleavage fragments. Another consequence is that the known carcinogenic effects of asbestos may be falsely attributed to non-asbestiform amphibole cleavage fragments of the same mineral. The purpose of this review is to assess whether amphibole cleavage fragments pose the same risk of lung cancer and mesothelioma characteristic of amphibole asbestos fibers. We identified three groups of workers exposed to non-asbestiform amphiboles: two groups exposed to grunerite (Homestake gold miners and taconite miners) and one group exposed to industrial talc containing non-asbestiform tremolite and anthophyllite in St. Lawrence County, NY. In addition to assessing strength of association and exposure?response trends in the non-asbestiform amphibole cohorts, comparisons were also made with cohorts exposed to the asbestiform counterpart (positive control) and cohorts exposed to the mineral (e.g. talc) that does not contain amphiboles (negative controls). The cohorts exposed to non-asbestiform amphiboles had no excesses of lung cancer or mesothelioma. Similar results were observed in the negative control groups, in stark contrast to the excess risks of asbestos-related disease found in the asbestos cohorts. The only possible exception is the twofold increased risk of lung cancer where exposure was to industrial talc containing cleavage fragments of tremolite and anthophyllite. However, this risk is not considered attributable to the talc or amphibole cleavage fragments for several reasons. A similar increased risk of lung cancer was found in Vermont talc workers, studied in the same time period. Their exposure was to relatively pure talc. There was no relationship between lung cancer mortality and exposure measured as mg/m3 years and years worked. A case?control study reported that all the lung cancer cases were smokers (or former smokers) and attributed the excess to smoking. There were two mesothelioma cases among the NY State talc workers exposed to cleavage fragments of tremolite and anthophyllite, but talc is not a plausible cause because of too short latency and potential for previous asbestos exposure. The positive controls of tremolite asbestos and anthophyllite asbestos exposed workers showed excess risks of both lung cancer and mesothelioma and positive exposure? response trends. St. Lawrence, NY talc does not produce mesotheliomas in animals while amphibole asbestos does. In sum, the weight of evidence fully supports a conclusion that non-asbestiform amphiboles do not increase the risk of lung cancer or mesothelioma. ©2008 Published by Elsevier Inc. Keywords: Amphiboles; Cleavage fragments; Lung cancer; Mesothelioma; Asbestos; Non-asbestiform amphiboles; Grunerite; Talc

Jan 1, 2007

The Greymouth Coalfield contains New Zealand&apos;s greatest known resource of bituminous rank coal. The coals are of very high quality, with low ash and sulphur contents and a range of other properties that makes them desirable for a wide range of uses. In fact only a few producers around the world today can offer coals with such exceptional properties. This suggests that Greymouth coal has potential as a premium export trading commodity. These assertions have been largely confirmed by a comprehensive exploration drilling programme funded by Mines Division û Ministry of Energy between 1979 and 1984. The program, forming part of the NZ Coal Resources Survey, was carried out under contract by Lime and Marble Ltd. The drilling of 49 deep, predominantly cored, holes at 1000 m intervals over the coalfield has generated a vast amount of data. It has shown the existence of three major potentially minable coal deposits containing 233 x 106, 33 x 106 and 15 x 106 tonnes of coal in ground. Investigations have at this stage only identified targets and these estimates represent &apos;in ground&apos; resources, not recoverable reserves. Recent geological studies as well as past and present mining have clearly highlighted the problems posed by the complexity of the coalfield geology. The coalfield lies within a mobile zone in the earth&apos;s crust known as the Paporoa Tectonic Zone, which has been active from at least mid-Cretaceous to the present time. Currently this factor poses the greatest obstacle to the determination of mining possibility of the, defined deposit and ultimately will strongly influence any future mining development. The Greymouth Coalfield has, however, had a long and eventful mining history spanning the last 120 years, where 32.5 x 106 tonnes of coal has been won from over 100 mines. In spite of the problems facing development, the large quantities and exceptional quality of the remaining coal will act as a strong inducement to persevere with this difficult but potentially valuable resource.

Jan 1, 1985

By Robert K. Guthrie, James W. Amyx, D. B. Taliaferro

"INTRODUCTION Secondary recovery of oil by water-flooding is practiced more extensively in North Texas than in any other section of the State, and the progress and experience of the operations in that area are of continuing interest to all branches of the oil industry. The first Bureau of Mines report on water flooding in North Texas 7/ chronicled the activities from December 7, 193f', when the Railroad Commission of Texas granted The Texas Co. the first permit to inject water into an oil-bearing sand, through 1944. This second report has been prepared as a supplement to Report of Investigations 3906 to show the progress and expansion of water-flooding. The format of this report is almost identical with what of report of Investigations 3906, except for a few miner changes. For the sake of brevity, certain basic information contained on the first report has not been repealed, and the reader is urged to consider the two reports as corporation writings.The North Texas area, as encompassed by the two reports, corresponds Railroad Commission of Texas Districts 7P and 9. Oil-development operations in the two districts, since oil was discovered in 1904, have resulted in the recovery of approximately 1,400,000,000 barrels of oil from a proved area that has been estimated to exceed 413,000 acres. During October barrels of oil was produces by primary and secondary-recovery methods from 1,746 flowing wells and 25,211 pumping wells, a daily average 6.6 barrels per well. Of this total volume of oil recovered in October 1947, 47,965 barrels (0.87 percent) was recovered from leases on which water-flooding operations were in progresses."

Feb 1, 1948