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By Firth B. A

The flotation of fine coal (minus 0.5 mm) often requires the addition of an insoluble hydrocarbon collector to apparently promote the adhesion of coal particles to air bubbles. A series of experiments was conducted using a radiotracer and narrow size fractions of clean coal to determine the effect of particle size distribution, collector addition rate, desliming of feed and emuIisification of collector on the distribution of collector between the different size fractions. The concentration of collector per gram of each size fraction was found to be approximately proportional to (average particle size)-2 except if the collector was emulsified prior to addition, the dependence altered to approximately (average particle size)-1. Mechanistic consequences are discussed.

Jan 1, 1982

By A. E. Lewis

The emphasis of this paper is on the characterization and testing of the slag produced by a secondary lead refinery. This work forms part of a broader investigation aimed at reducing loss of valuable product from the process as well as minimizing the environmental impact of the process wastes. It was this work that led to a critical examination of the standard waste classification tests. Characterization of the slag was carried out using a number of complementary techniques. In the broader context, the slag characterization aided in identifying process deficiencies and thus was a critical tool in suggesting potential for process optimization. For this study, the slag characterization provided a relatively comprehensive picture of the composition and properties of the slag, which facilitated understanding the behaviour of the slag under batch test conditions. On the basis of quantity of hazardous components alone, the slag is hazardous according to South African Acceptable Risk Limits (ARL). However, when both the quantity and the leach potential of the hazardous components is taken into account, standard waste tests carried out by three independent agencies indicate that the slag should not be classified as hazardous according to local regulations. Also, according to United States Environmental Protection Agency (US EPA) limits, which are independent of the quantity of the waste, the slag would not be classified as hazardous. The standard waste tests used by the independent agencies was the Toxicity Characteristic Leach Procedure (TCLP), a test which was developed by the US EPA to classify hazardous wastes. One of the requirements of this batch test is that it should be quick, simple to carry out and that the results should be reproducible. Previously, the applicability of the TCLP test to mineral processing and metallurgical wastes has been challenged on a number of points. Additional testing of the slag was carried out using both the TCLP and the Synthetic Precipitation Leach Procedure (SPLP) recommended by the American National Mining Association as being more appropriate for mineral processing wastes. The particular physical and chemical characteristics of the secondary lead slag highlighted additional limitations of both the TCLP and SPLP tests as standard laboratory batch procedures. Keywords: environmental protection, secondary lead processing, slag, leach testing, TCLP, SPLP, ARL, hazardous waste, batch tests

Jan 1, 2000

In recent years it has been more and more recognised that applied geology can be of service to the mining industry, and many mining companies overseas now have permanent geological staff as part of the operating organisation.Most of these companies insist that the geological department must pay for itself by the savings it can make in operating cost, and the growing use of the geologist is proof that such savings are made.The geological problems in every district are different, and a description of the problems and method of attack in a specified district is a useful addition to the literature of mining geology. Very few contributions, from the standpoint of the mining company geologist, have appeared in the Australian literature so that, although the operations of Bendigo Mines Limited are still in the development stage, and its geological work newly established, a description of the routine geological work at Bendigo should beof interest.Although most Bendigo mining companies have not employed permanent geologists, they have utilised geological guidance wherever possible, and a great body of data has grown up. Acknowledgment is made here to the valuable work of the Geological Survey of Victoria, especially the writings of E. J. Dunn, H. Herman, and H. S. Whitelaw, and the maps of Caleb Thomas and H. S. Whitelaw; and also to the work of independent investigators, notably Chief Geologist, Bendigo Mines Ltd.

Jan 1, 1936

By CLAYTON C. BALL

In the year 1948, more than ever before, the coal industry established itself on the threshold of a new and exciting future expansion. While production did not equal the wartime and peacetime peaks of 1944 and 1947, it was, in review, a good coal year. During the latter part of the year a combination of mild weather, record stock piling, and general business slackening reduced coal demand to the extent that marginal mines suspended operations, while mines remaining active found it necessary to renew their attention to producing better products at lower operating costs.

Jan 1, 1949

By P. Sanchez-Mejorada

GEOLOGISTS who are acquainted with the mines of northeastern Mexico realize that the most important lead-silver replacement deposits of the province are confined to a single formation. But since the formation is several hundred meters thick, the author has determined the relative position of the lead mantos in the belief that this information will prove useful in the search for new mines. This article describes the stratigraphic location of lead-silver replacement deposits known in several mines situated in a region comprising part of the states of Coahuila and Nuevo Leon. The area studied extends for 200 km* (125 miles) from east to west and 70 km (45 miles) north to south. Metallogenic Province: The most important metallic deposits of the region have the following common characteristics: 1) The orebodies occur as manto replacements of calcareous sediments. 2) The horizons that have contributed large tonnages of ore are in similar positions in the corresponding stratigraphic columns (as it will be shown later on). 3) Lead is the most important metal in the ores. Silver is commonly present in small amounts. Occurrence of zinc is dependent on the degree of oxidation of the primary sulfides. 4) A large proportion of the total production has been in the form of oxidized ores. 5) The deposits are located on anticlines. Rocks of Cretaceous age crop out over large areas of the states of Nuevo Leon and Coahuila. forming part of a belt that extends to the south along the eastern Sierra Madre. The sediments are cut by a small number of intrusive stocks ranging in characteristics from rhyolite to diorite. The most prominent structural feature of the region is a series of folds trending northwest-southeast. Faulting is not conspicuous in the region, although a major fault zone is found farther East.' The physiography closely reflects structural features, with mountains formed by anticlines and valleys conforming with intermediate synclines. Narrow valleys have also been developed along the axes of many anticlines, where solution of limy sedi- ments and erosion have proceeded along axial tension fractures. Stratigraphy: Rocks of the Upper Cretaceous are exposed in only a small percentage of the total area. Generally they have been eroded away from the mountains and are covered by recent talus and alluvium in the valleys. Humphrey' has published an excellent paper describing the Cretaceous formations of the Sierra de los Muertos, a short distance west of Monterrey. A brief summary of these formations is given below to convey an overall picture of the stratigraphic sequence that prevails just south of the area under consideration. Upper Cretaceous Indidura: Essentially thin shaly sediments. Cuesta del Cura: Limestone in thin wavy beds

Jan 1, 1959

By Arturo Ressi di Cervia

From the times when men in lacustrine environments drove wooden piles into the mud to elevate their dwellings, until the beginning of the twentieth century builders reacted to the conditions found in the location of their proposed structures by attempting to distribute their loads in ways that could be supported by the foundation's soils; or, if those were unsuitable, by moving the structure, whenever possible. While many major structures were built on stable ground (the pyramids were founded on rock), others were built on [ ]

Jan 1, 2000

By Don McCarthy

Modern mining has been dominated by the drill-and-blast method for more than a century. There have been steady improvements in drilling technology, explosive products, methods of initiation and integration of the two techniques but the essential cyclical nature of drill-and-blast rock excavation naturally limits continuous improvements in cost and productivity. Dynamite and safety fuses, compressed-airdriven tools, and most of the crushing and grinding machinery in use today were all developed before 1900. Moreover, virtually every mechanized mining system used today was in use by the late 1950’s.

Jan 1, 1998

By Ralph B. J, Sadler W. R

Thiobacillus ferrooxidans was shown to catalyse biodegradation of chalcopyrite concentrates. The process was growth associated at normal temperatures (30°C) in dilute acid solution (pH2, H2SO4) in submerged cultures. Approximately 20% of the copper dissolved in 22 days in the presence of T ferrooxidans while less than 0.6% was released when bacteria were absent. In ore column leachates, the iron and sulphur oxidizing species T ferrooxidans, ranged from I04 to I06 cells/ml while exdusively sulphur oxidizing species ranged from I02 to 104 cells/ml. T ferrooxidans predominated below pH 3 while other sulphur oxidizing bacteria favoured higher pH. Organisms were distributed vertically in ore columns according to pH differences, resulting from gradual acid consumption by gangue, during trickle irrigation.There was a sequential development of bacteria in leachates from fresh ore irrigated with water only. High pH sulphur oxidizers were always present, low pH sulphur oxidizers appeared within a week while T ferrooxidans took 50 days to show up. Routine monitoring of bacteria in dump leachates provided a qualitative indication of events in otherwise inaccessible ore bodies.

Jan 1, 1981

By L. C. IlsLey, H. H. Clark

In various publications relating to safety in mining the Bureau of Mines has called attention to the hazards attending the use of openBame lamps. An open-flame lamp is a potential source of danger in any coal mine. It may start a fire in a dry mine or an explosion in a gaseous mine. The type of open-flame oil lamp now used in mines is the product of long evolution; its principal merit is simplicity. That such a light is unsafe in an atmosphere containing gas (methane) is evident, and Sir Humphrey Davy immeasurably increased safety in coal mines when he found means of protecting a lamp flame so that it would not readily ignite gas. The safety lamp, however, gives less light than the open-flame lamp, is not as simple in construction, is more cumbersome, and must De carried in the hand .. Consequently, some miners are reluctant to abandon the open-flame lamp for the safety lamp, and risk their own lives and the lives of their fellow workers with the one rather than to be hampered by the other. When small electric bulbs, with their clear, white light, and small electric storage batteries became available, the advantage of combining these elements for a miner's lamp seemed manifest. The combination looked simple and safe, but was soon found to have elements of danger and weakness peculiar to itself. The Bureau of Mines showed, in 1911, that the breaking of a miniature electric bulb in an inflammable mixture of gas and air might ignite the mixture, so that only the fragile glass of the lamp bulb might stand between the miner and injury or death. There Was also a possibility that sparks from the small battery would ignite gas, and the accidental spilling of the contents of a battery on the miner's clothing or skin was a possible source of injury. The first portable electric miner's lamps that were carried in the hand, or with the battery strapped to the back and the light carried on the head, were exceedingly crude and were designed without appreciation of the sources of danger. The possibility, however, of producing a safe and practical miner's lamp by the proper combination and design of the elements available promised to increase safety so greatly that the Bureau of Mines attemr>ted to stimulate better design and construction by careful investigations and the establishment of an approval system that would be an assurance to the miner and an advantage to the maker of the lamp. As a result various manufacturers submitted types of lamps, cords, and bulbs for test and cooperated with the bureau in efforts to so improve the safety features of these devices that the lamps would P&$ specific tests for approval.

Jan 1, 1917

By Jr. Babcock

The Pyke asbestos deposits were discovered by Kennecott Explorations (Australia) Pty. Ltd., in 1969 during the course of base metal exploration on the South Island of New Zealand. Extensive occurrences of chrysotile asbestos were found associated with the Red Mountain Ultramafics in the headwaters of the Pyke River, and to the north and south along the ultramafic belt for a distance of 70 kilometers. Surface evaluation and drilling by Kennecott in 1970 and 1971 identified numerous small deposits of good grade fibre in the Little Red Hills between the Pyke and Barrier Rivers. Additional drilling and three adits have been completed by other companies since that time. The property is presently held by Lime and Marble, Ltd. Of Nelson, New Zealand, and Kennecott Explorations (Australia) Pty. Ltd. This paper will present the regional and local setting of the asbestos deposits, including the geology and nature of mineralization. In addition, the exploration methods used by Kennecott in the discovery and evaluation of these deposits will be outlined. Subsequent work by other companies will be mentioned, but not described in any detail. This subsequent work did not alter Kennecott's conclusions or produce any serious changes in the interpretation of geology and mineralization. The author acknowledges the contribution of the many employees of Kennecott Explorations (Australia) Pty. Ltd., who have been involved in the project, particularly Ramon Farmer, N. G. Comer, and A. W. McConie, who were responsible for completion of field work and reporting on the project. The responsibility for the conclusions and interpretations of this report are solely that of the author and result from his involvement in discovery of the deposits and management of the exploration program.

Jan 1, 1978

By J. E. House, C. J. Lewis

In the solvent extraction process, also referred to as liquid-liquid extraction, the clarified uranium-pregnant sulfuric acid leach solution is contacted with an organic extractant dispersed in kerosene; the uranium enters the organic phase and associates itself with the organic extractants. Simultaneously an-ions or cations, as the case may be, leave the organic extractant phase and enter the aqueous phase. The two phases are then allowed to separate by virtue of their immiscibility. Based on the data available, a generalized procedure for the recovery of molybdenum from the sodium carbonate scrub liquor of acid leach uranium mills using secondary and tertiary amine extractants is presented, as is another generalized procedure for the recovery of molybdenum from the bleed stream of alkaline leach uranium mill circuits. Such economic appraisal as can be made at this stage of the development is also indicated. Molybdenum occurs in most uranium ores. Whether the uranium is solubilized by the acid leach route or by the alkaline leach process, some of the molybdenum present in the ore is solubilized along with the uranium. Molybdenum in uranium mill pregant solutions may cause processing difficulties, among which may be mentioned the poisoning of resins, the precipitation of organo-molybdenum complexes, or the build-up of molybdenum in recycle streams. While the uranium milling industry has been successful in applying measures to overcome the problems arising from the presence of molybdenum in the circuits, such measures nevertheless add to the cost of producing uranium yellow cake concentrate. Table I shows the analysis of typical uranium pregnant leach solutions. Uranium recovery by solvent extraction is presently practiced only in conjunction with acid leach circuits, and it may be noted that of about 16,000 tons of uranium ore daily processed by sulfuric acid leach, more than half of this tonnage follows the solvent extraction route. Uranium mills leaching ore with sodium carbonate-sodium bicarbonate solution (the so-called alkaline leach circuit) do not use solvent extraction. In this case the uranium pregnant solution is sufficiently pure to permit the direct precipitation of uranium concentrate with subsequent recycle of the alkaline leach solution. While solvent extraction procedures may be developed which are economically attractive for the alkaline leach uranium process, this has so far not been the case. The earlier uranium mill solvent extraction circuits used organo-phosphate extraction reagents, among which di-2-ethylhexyl phosphoric acid was popular. It should be borne in mind that uranium in its sulfuric acid leach solution exists in an equilibrium involving uranium in both anion and cation forms: uo + 2S0 = [uo2(so4)2] For this reason uranium may be extracted by either cation extractors or anion extractors and this is likewise true of molybdenum. However, the organo-phosphate extractants also load ferric iron which is usually present in the uranium acid leach solution. For this reason, it is necessary to reduce this solution substantially to the ferrous state ahead of solvent extraction using organo-phosphate reagents. The amines, being anion extractors, selectively reject iron and thus render the iron reduction step unnecessary. In the solvent extraction process, also referred to as liquid-liquid extraction, the clarified uranium-

Jan 1, 1961

By Walter C. Woodmansee

The only reported mineral production in 1977 was small output of alluvial gold, valued at an estimated $54,320.2 In addition, marine shells are gathered for use in lime manufacture, although output was not reported. Proposed development of a bauxite mine and smelter, involving Rennell and Vaghena Islands, was deferred in June. Conzinc Riotinto of Australia Ltd. (CRA), in partnership with Mitsui Mining & Smelting Co. Ltd., and the Solomon Government, with- drew from the project, and Mitsui, which conducted a feasibility study and metallurgical testing of the bauxite, decided to defer further work because of slack demand for aluminum in Japan and difficulties in arranging financing. The Mitsui feasibility studies reportedly indicated that the project could be viable despite technical difficulties and relatively high initial investment costs. The project was to produce 1.5 million tons of bauxite and 600,000 tons of alumina per year from reserves totaling 60 million tans at 45% to 50% A1203.

Jan 1, 1981

By J. A. Herbst

During the last decade it has been established that conventional flotation control strategies based on classical control theory result in significant increases in grade, recovery, and operating-cost savings. In the current report a description of an advanced model-based control philosophy is presented. The derivation and verification of a simplified flotation model is described. The implementation of a Kalman filter for estimation of unmeasured variables for input to controllers is discussed. Several control strategies using the model-based approach are described, emphasizing the nonlinear nature of the flotation plant. Expected trends in the implementation of such model-based flotation control strategies in the future are discussed.

Jan 1, 1986

If lead buttons are cupelled under closely controlled conditions in a suitable design of furnace, silver losses during cupellation are given by a simple equation. The effect of copper on these silver losses has been studied and a "copper limit" for cupellation has been determined. Scorification and crucible fusion procedures for copper-bearing materials have been designed so that the lead buttons produced will not contain amounts of copper greater than this determined copper limit. Silver losses during these crucible fusion and scorification procedures are given by the distribution law, and can be calculated. Thus, silver can be determined in copper-bearing materials with a satisfactory degree of accuracy provided that the appropriate corrections for losses are applied to the weight of the silver prill produced.

Jan 1, 1957

By Verma UK

Mining for sand was active in South Delhi during the last four decades disregarding all norms of safety. The aim of the paper is to highlight what is proposed to be done for mining in Delhi. Apart from the damage to the landscape, the earlier operations gave rise to visual pollution to the scenic Delhi area and there is immediate need of land restoration and landscaping. Future mining should be planned so that the resultant land surface completely merges with the topography and gradually assimilates with the green belt. Restoration of old workings, land reclamation and details of plantation in old pit areas are included. The project also provides a demon- stration site to show the impact of eco-development leading to new legisla- tive measures, as it is in the Capital of India itself and therefore more accessible than any other area. What has been suggested for mining is not the latest and the most modern equipments from the Western point of view but the right equipment to meet the specific requirement of the country. Financial projections are included alongwith technical details of the project to show the benefits to the society. It is concluded that eco-development is essential for the mining in the Twenty- First Century.

Jan 1, 1986

By S J. Brace

About 180 000 tons of explosives are used annually underground in South Africa. Most is loaded into holes less than 50mm in diameter. 75% is consumed in the gold and platinum mines where holes are between 25 and 4omm in diameter and no more than 3.0m in length. The small amount of explosives per hole with extreme conditions of heat, humidity and seismic activity, make the choice of explosive on safety and technical grounds very important to the success of a blasting operation. Taken together with the fact that many underground precious metal operations are now marginal then the choice of an explosive, when its price is also considered, becomes critical to the very viability of some mines.

Jan 1, 1994

By C. A. Young, J. D. Miller

The surface chemistry of the calcite/oleate flotation system was examined by in-situ FT-NIR/IRS. Spectra of combination and overtone bands of aliphatic stretching vibrations revealed gauche/trans conformational changes that occurred solely as a function of temperature. The conformational changes were attributed to the simple "melting" behavior associated with phase transitions. It was concluded that chemisorbed oleate at calcite surfaces is gel-like at temperatures below 22oC, resembles a coagel between 22oC and 31oC, and becomes micelle-like at temperatures above 31oC. By comparison, chemisorbed oleate at fluorite surfaces also undergoes these phase transitions but is additionally dependent on adsorption density. The conformational changes were observed at high chemisorption densities (> 2.0x10-10 mol/cm2) and attributed to molecular forces, primarily van der Waal's interactive forces, among neighboring chemisorbed oleate molecules. Similar analysis of in-situ FT-NIR/IRS spectra of surface-precipitated calcium dioleate at calcite surfaces did not exhibit this behavior thereby confirming that surface-precipitated calcium dioleate remains in an all-trans conformation. The results help explain why surface polymerization is not observed at calcite surfaces but is observed at fluorite surfaces.

Jan 1, 2002

The general nature of the special constructional features that are required to provide safety from explosion hazards on machines approved as permissible by the Bureau of Mines is fairly well known to mining men who are at all interested in safety. These requirements are outlined in the schedules under the provisions of which the investigations of such machines are conducted. Also, the method of conducting inspections and tests of such machines has been described in Bureau of Mines Bulletin 305, Inspection and Testing of Mine Type Electrical Equipment for Permissibility, published in 1929. A more detailed knowledge of the special safety features of a particular machine is often useful and sometimes essential for inspectors, safety engineers, maintenance men, and engineers in selecting machines for a particular application. Three bulletins that give information of this nature have been-published by the bureau, viz., Bulletin 313, Permissible Storage-Battery Locomotives and Power Trucks. Bulletin 343, Permissible Coal-Handling Equipment. Bulletin 382, Permissible Coal-Cutting Equipment. Report of Investigations 3309, Permissible Electrically Operated Air Compressors, which contains similar information, was issued in August 1936, and a Report of Investigations 3326, Permissible Electrically Operated Room Hoists, was issued in January 1937. Thus, the present paper is the third to give detailed information concerning permissible machines of types not included in bulletins, and covers all the rock-dust distributors approved prior to October 1, 1936.

Jan 1, 1937

By Jacqueline H. Jansky

The Mine Safety and Health Administration (MSHA), U.S. Department of Labor, did a linear analysis for a new underground coal mine in Grant County, WV, through the interpretation of LANDSAT imagery and high-altitude, color-infrared aerial photography, to identify areas of potentially unstable roof in advance of mining. The Bureau of Mines included this mine in its ongoing study of the correlation between geologic features and linears. Three years after the analysis, after mining had progressed through the plotted linears, a cooperative Bureau-MSHA study evaluated the effectiveness of the linear plot in predicting areas of unstable roof and defined the geology associated with the linears. Adverse roof conditions at this mine include roof falls, potted-out roof, water inflow, and local areas requiring supplemental support. At the time of this study, 34 pct of the mine workings were within 200 ft of a plotted linear. Fifty percent of the adverse roof area in the mine occurred within this area. The primary geologic anomaly associated with the linears is an increased frequency of jointing. The majority of the plotted linears coincide with the prominent joint orientations. Additional features observed in the linear zones include roof rolls and a sandstone channel that cuts into the coal seam.

Jan 1, 1983

By Vance G. Leak

A technique for recovering copper and steel from metallic scrap has been developed by the Bureau of Mines based on preferential melting in molten salt baths at 1,150° to 1,250° C, The molten salt, preferably barium chloride or calcium chloride, both minimizes oxidation of the metals and promotes heat transfer. Cleanest separations (0.01 percent copper remaining in iron) have been achieved by pretreatment (dipping or spraying) with sodium sulphate or sodium silicate, which alters and coats the surface of the iron to inhibit the alloying or brazing with copper. An economic evaluation of the process was carried out on six combinations of sweating media and inhibiting reagents. On the basis of the postulated model, a cost of about $0.20 per pound of copper recovered has been determined for the sweating treatment operation.

Jan 1, 1973