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By P Lukic

The definition of the working sections that will be used in a mine is usually initially made in the field by the geologist supervising the drilling program. These initial definitions are often made on the basis of rules of thumb such as æcoal less than 30 cm thick cannot be mined separatelyÆ; æpartings more than 30 cm thick will be mined separatelyÆ; and æif a coal seam is less than 50 cm thick and the parting above or below is thicker than the coal, the coal will be wastedÆ. These decisions are also often made based on the requirement for a minimum sample mass for analysis, and the desire to collect data at the minimum resolution to conserve the exploration budget.In many cases the geological models based on this data are produced at a resolution that is inadequate to allow the mining engineer to produce a mine plan that will maximise project value. This problem is generally unrecognised.Where data is collected to a higher level of resolution the subsequent processes employed in the production of geological models and mine plans often discards the inherent value that is hidden in this data. Again this problem is generally unrecognised.This paper highlights this problem and then presents a methodology that ensures that the optimal working section is selected and compares the outcomes of applying this methodology versus adherence to the usual rules of thumb.

Sep 26, 2011

||Abad, Leopoldo F, Min Engr, Div of Mines, Bureau of Science Manila, P I '23 Abadilla, Quirico A, Geol , Logo Pet Corp Box 172, Maracaibo, Venezuela '20 ||Abarquez, Ramon F, Met, Bureau of Science Manila, P I '24 ||Abbey, Robert Graham, Student, Case School of Applied Science Cleveland, Ohio '21 Abbott, A N , Mines Supt, Mazapil Copper Co, Ltd Concepcion del Oro, Zac , Mexico '23 Abbott, Clarence E , Mgr, Mines & Quarries, Tenn Coal, Iron & R R Co. 1242 Brown Marx Bldg, Birmingham, Ala '04 Abbott, Louis Benjamin, Chief Engr, Consolidation Coal Co, Elkhorn Div Jenkins, Ky '15 Abbott, Robert R , Met Engr, Peerless Motor Car Co Cleveland, Ohio '12 ||Abbott, Wells Osborn, Ray Consolidated Copper Co Hayden, Ariz '23 Abeel, George H., Jr, Cons Min Engr 4612 W 17th St, Los Angeles, Cal '18 Abel, Albert E , Asst to Pres , Valley Mould & Iron Corp Sharpsville, Pa '19 Abernathy, George Elmer, Prof of Geol & Min , Kansas State Teachers College, Pittsburg, Kan '20 Abey, Hiroshi, Min & Met Engr, Chief Engr, Takata Min Co, 2 Yeirakucho, Nichome, Kojlmachiku, Tokyo, Japan '17 ||d'Ablamg, Philip R , Millman, Old Dominion Silver-Lead Co Ellensburg, Wash '25 Aborn, R H, X-Ray Metallographic Research, Mass Inst of Tech Cambridge, Mass '19 Abouchar, Sylvain Sley, Min Engr & Geol, care of S H Sekaly, 13 Rue El Nimr.

Jan 1, 1923

By F. S. Sinnatt

THIS paper is the outcome of an extended investigation carried out in association with Dr. L. Slater. The inquiry had been continued in various directions and a number of results are quoted from an investigation recently completed by S. H. Jenkins. In projecting the work some five years ago, the author had in view a general attack on the problem of the spontaneous combustion of coal from an angle that had received little attention. The basic idea was to obtain a "slow motion study" of the active combustion of coal. This included an examination of the conditions prevailing in a mass of coal at the moment when active combustion ceases. It was thought that, if the factors governing the extinction of combustion in coal could be definitely established, it might offer an explanation of the manner in which the spontaneous combustion of coal originates. The inquiry arose from a detailed study of the properties of fusain that the author began in 1918. Fusain seemed to possess characteristics quite distinct from the coal with which it was associated, for if it were collected into a heap and one portion were heated by a small flame the combustion would traverse the whole mass. This combustion was not accompanied by smoke and passed slowly through the heap of material. Later, it was found that coals, including anthracites, would behave in a similar manner provided they were in the form of powder and that the particles were smaller than a certain size. The limiting size of particles is a definite characteristic of the coals investigated. In view of the fact that fusain exists with coal in a state that enables it to undergo this particular form of combustion, it must be assumed, sometimes, to playa definite part in the spontaneous combustion of coal in the goaf (waste).

Jan 3, 1925

By M. R. Geer

THE importance of the size composition of coal is reflected in the differ-ence in price of the various sizes of the same coal and in the large number of primary sizes and mixtures of sizes produced by the modern preparation plant to meet the demands of a market that in late years has grown increasingly conscious of coal size. The importance of size in the indus-trial and domestic uses of coal has its counterpart in the role played by size composition in the laboratory examination of coal. Investigation of many of the physical properties of coal in their relation to its uses requires an evaluation of size composition. In fact, the Standards on Coal and Coke issued by the American Society for Testing Materials in 1936 contains 12 standard methods of testing that involve some use of size composition. The screen analysis is, of course, the standard method of determining size composition, whether the material is coarse run-of-mine coal or fine pulverized fuel. Customarily, the analysis is reported as the weight percentages retained on or passing each of a series of testing screens, the number of which may range from only two or three to as many as 20. When more than two or three sieves are used, which is usual, the number of weight percentages obtained is so great as to make the analysis difficult to comprehend. Direct comparison of analyses made on the same sieves is hard, and comparison of analyses covering the same range of sizes but made oil different sieves is next to impossible. Consequently, a frequent purpose of sizing tests-correlation of size with properties and charac-teristics related to size-is rendered difficult.

Jan 1, 1938

By Crockford GI

Some twelve months of operation at Mount Lyell, using two large diameter ball mills as a two-stage grinding circuit indicated a short- fall in the grinding capability compared with design criteria. Breakage, particularly at coarser sizes, was less efficient than with the previously used grinding circuit comprising a large number of smaller diameter mills. This paper describes both old and new equipment, puts forward the facts as they are presently known, and lists the attempts made to overcome the problem.

Jan 1, 1978

By Thomas MacFarlane

DURING the last fifteen years the progress made in the science of lithology has been of a very marked character. From being a miscellaneous collection of facts and observations regarding certain mineral aggregates seemingly incapable of systematic arrangement, it has become a most interesting and orderly department of science. The investigators who have brought about this great change have recorded the results of their labors, and placed at our service an extensive and varied literature on the subject. To this I have paid some attention, and partly from .studying it, partly from my own observations, I have wrought out a classification of original or crystalline rocks, which I venture to bring under the notice of the members of this Institute. The practical importance of the subject will be acknowledged when it is considered that rock species are not without their influence on the contents of the mineral veins which intersect them. Besides, the Institute has been doing good service in defining terms in metallurgy, and no doubt in mining and geology we might

Jan 1, 1880

By Frank J. Wiebelt

The Veta Chica and Cerro Colorado chromite deposits of the McGuffy Creek area, Siskiyou County, Calif. were selected as worthy of investigation by the Bureau of Mines in accordance with the Strategic Minerals Act of 1939. These were two of many chromite deposits examined by engineers of the Bureau of Mines during their extensive wartime mineral examination and exploration campaign. Exploration by the Bureau of Mines consisted of 2,234 feet of diamond drilling, surface trenching, and sampling during the months of May and June 1942.

Jan 1, 1949

By Rolly Thorpe

Bulk emulsion explosives have been used at surface mines and quarries for many years. Recently, this technology has been adapted for underground use in relatively confined work areas and in smaller diameter blastholes.

Jan 1, 1994

NORTH AMERICA Number Members Alaska 36 Canada 323 Mexico 184 Newfoundland 3 United States Alabama 40 Arizona 111 Arkansas 8 California 646 Colorado 171 Connecticut 90 Delaware 21 District of Columbia 136 Florida 16 Georgia 7 Idaho 66 Illinois 208 Indiana 66 Iowa 11 Kansas 24 Kentucky 32

Jan 1, 1934

By S. O?Connor

When one looks back and does assessments of what has been the key ingredient in achieving success in our safety efforts, there are many issues that spring to mind and cover a wide array of elements. One does not know which has the ultimate maximum effect. In his presentation yesterday, Alan Peers, our SHEQ leader, covered a lot of detail with the way we are managing safety at Modikwa. I have attempted to identify some of the key essentials in making the mine safe. Passion Safety is addressed with a passion that is unbelievable at times. When I get phoned because an incident has occurred and in reporting the incident, there are already action plans being put in place to prevent re-occurrences, you understand the commitment to put employees? safety first. You hear the disappointment in your subordinates? voices when they have to share the fact that an incident or accident has occurred.

Jan 1, 2011

By E. D. Gardner

This paper is one of a series on milling methods being published by the United States Bureau of Mines. Atlanta is in Elmore County, Idaho, about 80 miles from the railroad at Mountain Home, Idaho. The concentrator is at an elevation of, 6,000 feet and located in a timbered, well-watered region of relatively heavy snowfall. The snow, however, does not seriously affect local operations. The track road to Mountain Home, which passes over a mountain range, is closed each winter from about November 1 to June 15. During this period concentrates are stored and bullion is shipped by airplane. Power is generated by a Diesel engine and by an auxiliary hydroelectric plant. Gold is the principal metal produced; the or also contains an able quantity of silver.

Jan 1, 1935

By R. Q. Honaker

A significant problem in ultrafine particle classification is the significant amount of submicron particle by-pass to the coarse particle stream. In classifying cyclones, submicron particle by-pass to the underflow stream can be reduced by decreasing water recovery. Past studies have shown that a reduction can be realized when the feed solids concentration is increased or the apex diameter is reduced. However, both adjustments tend to increase the particle size cut point and negatively affect classification efficiency due to the impact on slurry rheology. The addition of a viscosity modifier to the feed stream of a classifying cyclone improved the classification performance and decreased the particle size cut point over a range of feed solids concentrations. The detailed test program investigated the use of the modifier in conjunction with varying apex diameters to identify conditions that minimize ultrafine by-pass. With small apex sizes, roping conditions were readily eliminated by the addition of viscosity modifiers. The addition of the modifier had no deleterious effect on froth flotation performance, which commonly serves as a downstream separation process. The fundamental and practical benefits of viscosity modifiers in classification processes are discussed in this publication.

Jan 1, 2006

By Irving M. Symonds

COMPA[N]IA Minera de Penoles, S. A., at its Avalos unit operates a lead-zinc concentrator having a capacity of about 600 short tons per day. Lead and zinc concentrates are made by flotation methods. The concentrator is at Terminal de Providencia, in the state of Zacatecas, some 70 miles south of Saltillo, Coahuila. The Pe[n]oles-Avalos railroad operating between the plant and Estacion Avalos, a distance of 6 miles, makes connections with the Coahuila and Zacatecas railroad, which in turn connects with the Nacionales de Mexico at Saltillo. The three railroads are each of different gauge, requiring the transfer of all supplies and concentrates at each junction. The mill operates on company ores, on ores from leased mines, and as a custom mill. The custom business is very small. The lead concentrates are shipped to company smelters at Monterrey, Nuevo Leon and Torréon, Coahuila. Since the European war, all zinc concentrates have been shipped to the United States. ORE TREATED The major source of ore supply is a group of four mines owned or leased by the company, some three miles south of the mill in the mountains, from which the ore is delivered to the mill by a gravity aerial tramway. Custom ore comes in by rail. The ores occur in chimneys. The upper levels contained oxidized siliceous ores of lead, copper, silver and gold, with varying amounts of zinc. These ores were direct-smelted. In the first two years of operation a good deal of the tailing loss was caused by the oxidized content of the ores milled. Much of the ore in the transition zones between the oxides and sulphides was not mined. The ores now being milled are clean, hard sulphides in a limestone gangue, with only occasional contamination of oxides. The lead and zinc sulphides are of coarse structure and are freed even above flotation sizes. The galena is usually "steel" colored, easily and quickly floated. When there is any oxidation, it is usually on the coarsest crystals. The zinc minerals vary a good deal in color; a resin sphalerite predominates but there are varying shades of brown marmatites. On an average, the zinc sulphides contain 64 per cent zinc. The only common copper mineral is chalcopyrite. Little is known of the occurrence of gold and silver. Waste minerals are mainly limestone and pyrite, both of which are barren. The ores vary from 20 to 35 per cent pyrite. Mill heads for the year 1940 and the first eight months of 1941 are given in Table I. [ ]

Jan 1, 1942

By Matthias Baeßler, Markus Herten, Ernst Niederleithinger, Steven Georgi

"Abstract: BAW and BAM have performed a large scale comparison and calibration test on static and dynamic load capacity evaluation of bored piles in glacial sandy soil. The test was performed using eight piles at the BAM test site for technical safety at Horstwalde 50 km south of Berlin. The test area has been prepared and investigated in great detail using boreholes, cone penetration tests, pore pressure sensors and geophysical methods to assure controlled conditions for all piles and tests. The piles (10 m length, 0.9 m diameter) are mainly friction piles (low toe resistance) and have been checked by integrity testing. Five piles have been tested by five contractors using the dynamic method in a blind experiment, the other ones piles by static load and/or later on by the dynamic method. Some piles have been equipped with additional fibre optic instrumentation which proved to be robust and helpful in interpreting the results of static, dynamic and integrity tests. We have experienced a deviation of the dynamic load test results gathered in the blind experiment from the static values of up to 20% in most cases, sometimes even up to 30%. This can be related to the known soil inhomogeneities, interpretation and modelling in CAPWAP and method inherent uncertainties. In cases where the static values were known by the testers for calibration, the deviations were significantly smaller. It has to be taken into account, that the two static load tests showed different results as well. Due to the low toe resistance, use of a big drop weight (11 tons) and large drop heights most piles suffered from cracking, which was clearly seen in follow up integrity tests and confirmed by excavation. The piles are available for further research.IntroductionBored piles are used in many construction projects of the German waterways authorities, e. g. bridges, piers or locks. Their load carrying capacity varies with pile type and geometry as well as soil type, parameters and structure and is thus not easy to calculate in advance. Dynamic pile testing as a cost effective addition or replacement for expensive load tests is accepted in many places (Beim and Likins 2008) but still doubted in others. Inspired by the international prediction event for piles in residual soil carried out in the frame of ISC’2 (Viana de Fonseca and Santos 2008), governmental research institutes have designed an experiment in a geological setting typical for glacial and post-glacial areas in northern Germany. Some results have already been presented by Niederleithinger et al. (2012), Herten et al. (2013) and Baeßler et al. (2013). It was intended to perform a blind test for load capacity estimation using dynamic pile testing on six drilled shafts involving five test crews. Two other piles would have to be tested thereafter using static and dynamic methods."

Jan 1, 2014

By Karl-Heinz Obst, Juergen Stradtman

The importance of the chemical and physical properties of lime has been overlooked for years although the quality of lime plays an important role in the production of steel. With the introduction of the oxygen injection process these properties have been re-evaluated. The CaO, MgO, S, and P2O5 contents of lime are important, but so are the physical properties such as granulation, reactivity with respect to slag formation, and the degree of burning. Soft burnt lime enhances de-phosphorisation and de-sulphurisation, and facilitates the smelting process in general, mainly due to its large specific surface. Special lime, prepared as briquettes from quicklime and fluxes or as pellets from limestone and various fluxes with or without binding agents, clearly accelerates lime dissolution during the slag formation process, lowers the melting point, and enhances de-phosphorisation, de-sulphurisatlon, and de-carburisation even more than soft burnt lime. The introduction of special limes in the oxygen injection process for steel production has opened up new fields for commercial exploitation of slags as well as improved operational techniques.

Note: This is a progress report and therefore not necessarily conclusive. Further data may result in conclusions somewhat different from those reported here. Crop Growing Season The monthly average temperatures, total precipitation, and evaporation for the demonstration mine are shown in Table 1. [ ]

Jan 1, 1980

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Jan 1, 1938

By Masanori Mori, Hajime Miki, Osamu Ichikawa, Tsuyoshi Hirajima, Mitsuru Sawada, Keiko Sasaki

For pretreatment of selective flotation, surface oxidation of chalcopyrite and molybdenite was applied by oxygen plasma then the minerals were washed by solution at pH 9 with oxygen bubbling. Surface characteristics of these minerals were investigated with AFM, XPS, zeta potential and contact angle measurements. Contact angle of chalcopyrite and molybdenite decreased a lot by plasma treatment. When they were washed with pH 9 solution with oxygen bubbling, contact angle of molybdenite increased whereas chalcopyrite one kept low. Adhesion force measurements indicated similar behavior. Result of flotation experiments indicated low recovery of both chalcopyrite and molybdenite after plasma treatment and only molybdenite recovery became higher after washing. Selective flotation of chalcopyrite and molybdenite could be achieved with this process. Possible mechanism of selective flotation was proposed from the results of XPS, AFM, etc.

Jan 1, 2014

By M. J. Sheridan

"INTRODUCTION In December 1942, the-Bureau of Mines reported favorably on a proposal to grant Government assistance-in constructing an access road (consisting principally of a timber-pile bridge across the Rio Grande at Hot Springs, N. Mex.) to the property under lease to the United States Fluorspar Co. At that time the property was being developed actively, and there appeared to be no immediate-need for exploratory or metallurgical assistance by the Bureau of Mines.Because milling facilities were inadequate; the access-read project was eventually disapproved, but prior to disapproval the company had discontinued operations. In June 1943, exploration was resumed by the Humphreys Gold Corporation of Denver, which had subleased the property. Difficulty of access continued to interfere with exploratory progress. In July 1945, at the request of the lessee, the Bureau of Mines directed sampling, using company employees.At the completion of this sampling program, the Bureau of Mines concluded that the property was potentially a important source of fluorite but that further development for production appeared to depend largely on the establishment, by exploration, of adequate reserves. Because of the relatively easy position-of metallurgical-grade concentrate and ores, it also was deemed advisable to investigate the possibility of producing acid-grade concentrate from the ore, for which a demand was becoming evident. Accordingly, a program of trenching, diamond drilling, and metallurgical testing was undertaken by the Bureau. The results of its investigation are reported herein."

Feb 1, 1947

By McPherson M. J

This paper describes a major ventilation study for the expansion of the El Teniente mine operated by Codelco, Chile. El Teniente is one of the world's largest under- ground mines. The design effort was under- taken in three stages and involved a partial mine ventilation survey with network simula- tion, detailed stope ventilation investiga- tions, and design of the entire mine ventila- tion circuit based on production plans to achieve 112,000 tons per day by 1995. The partial ventilation survey provided values of representative friction factors and resistances for typical ventilation raises and airways. These values were used to conduct detailed modeling of the block caving levels to investigate the most cost effective and practical means of providing the required ventilation. The results of these analyses were extrapolated to the proposed expanded mechanized zones.

Jan 1, 1988