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By M. Vulkov

The paper is focused on the optimal selection of grinding medium for a drum mill. The decision-making is based on the fuzzy multiple attribute approach. One way to optimize the grinding process in a tumbling mill is associated with the development and testing a new shape of grinding body. Family of new grinding bodies ? spheroidal tetrahedrons (tetraballpebs) has been manufactured. Two types of spheroidal tetrahedrons and a classical ball (sphere) with one and the same weight are compared. A fuzzy entropy method to calculate the weight of the attributes is suggested. A grinding body which is the best approximation to the fuzzy formulated technological conditions is selected. Keywords: grinding, spheroidal tetrahedrons (tetraballpebs), balls, fuzzy sets

Sep 1, 2012

The Macraes Mining Company Limited was listed on the New Zealand and Australian stock exchanges in January 1990, and the proceeds of the float were used to purchase a 70 per cent interest in the Macraes Gold Project, previously owned by BHP Gold Mines (NZ) Limited. Macraes Mining has had a 30 per cent interest in the project since May 1984, when it was incorporated. Project financing in the way of a gold loan was secured in February 1990 and construction commenced shortly afterwards. The mine construction activities were completed within nine months and the mine commenced operations in October 1990.

Jan 1, 1991

By L. Allan White

Instrumental analysis is an indispensable tool to many phases of research on rare-earth metals and their compounds; therefore, the development of new and improved instrumental techniques is essential. This report describes an emission spectrometric analytical method using direct-current carbon-arc excitation of various rare-earth-oxide mixtures. Lanthanum oxide serves the dual purpose of an internal standard and a constant major constituent. The versatility of the method was demonstrated by three different applications: (a) Analysis of complex rare-earth concentrates; (b) determination of impurities in high-purity rare-earth oxides; and (c) detection of rare-earth elements in other types of matrices, such as those resulting from beneficiation of rare-earth ores. The average error of analysis in the concentration range of 0.2 to 10.0 percent was 14.6 percent for a group of complex synthetic mixtures of rare-earth oxides. An average error of analysis in the concentration range of 0.05 to 0.50 percent was 21 percent for a group of high-purity rare-earth oxides.

Jan 1, 1959

By J Ward, B Rohrlach, B Rosero, J Silva, O Poma

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Alpala copper-gold deposit is a recent, high-grade porphyry Cu-Au discovery located in the Imbabura Province of north-western Ecuador. The deposit lies along the crustal-scale Chimbo-Toachi Fault Zone within the Dagua-Piñon terrane, which is an oceanic plateau accreted to the South American convergent margin in the Late Cretaceous. The deposit is hosted by quartz diorite stocks that intrude andesitic volcanic breccias of the Oligocene to mid-Miocene San Juan de Lachas Formation. Miocene-age calc-alkaline plutonism is associated with porphyry Cu, Cu-Mo and Cu-Au deposits in southern and northern Ecuador. The Alpala deposit lies along a sector of the Miocene arc that has recently been underplated by the Carnegie Ridge seamount chain that induced shoaling of the subducted Nazca plate beneath northern Ecuador.Surface expressions of the deposit were recognised in May 2012 during follow-up of stream sediment anomalies, when outcropping sheeted and stockwork porphyry-related veins were discovered in Quebrada Alpala. The roots of a NW-trending, structurally-controlled lithocap were recognised over an area of 4.5 × 0.9 km. The remnant lithocap exhibits well-defined mineral zonation mapped by TerraSpecTM analyses on grid soil samples. Soil sampling, heliborne magnetic surveying and channel sampling defined initial drill targets.Seven diamond drill holes were completed in the year from September 2013. Drill hole CSD-13-005 intersected 672 m grading 0.93 per cent Cu and 0.91 g/t Au in high-temperature, inner propylitic and locally potassic-altered quartz diorite intrusions. Overlying hydrothermal clay alteration assemblages define the base of the lithocap. A NW–SE trending footwall structure defines the south-west margin of the deposit. Drill hole 5 intersected high-grade sheeted ‘B-type’ and ‘C-type’ veins (Gustafson and Hunt, 1975) that lie along the south-west margin of an 1100 × 500 m magnetic anomaly that is the focus of ongoing exploration.CITATION:Rohrlach, B, Poma, O, Rosero, B, Silva, J and Ward, J, 2015. High-grade porphyry copper-gold mineralisation in north-west Ecuador – The Alpala Cu-Au porphyry discovery , in Proceedings PACRIM 2015 Congress, pp 369–376 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By J. O. Lewis

"The significant facts in the problem of the relation between the production of crude petroleum, and the ever-increasing demand for petroleum products are that in spite of continually increasing production, improvements in methods of refining and utilization, and heavy increases in imports, demands grow still more rapidly and we seem always faced with a shortage at hand or lust ahead. On the other hand, our foremost authorities warn um of entirely inadequate domestic reserves. Looking abroad we find some large fields and many of speculative promise, 'tut the situation is complicated by international relations and demands by other countries which promise to be even more insistent than oars. This is the situation, then. We can not rely upon our own Crude Petroleum to meet the Ever Increasing Demand for Petroleum Products.I wish to follow this somewhat alarming statement by saying at once that the Bureau of Mines is not pessimistic in facing this situation. To my mind those who discuss the oil situation may be placed in three categories; the pessimists, the optimists, and the super-optimists. The pessimists I call those who see darkly and will concede no possibility of solution. According to them a few years will see the automobiles piled in windrows of 'dilapidated junk, I have no sympathy with this point of view and deem it vicious and entirely unwarranted.The optimists I term those who believe that there is a solution and that we shall be able to meet all of our reasonable requirements for as far into the future as can be foreseen, yet who recognizes that this desired end can not be attained without prevision and energetic effort.The super-optimists are those who will say to you, ""There is nothing to this talk of shortage, whenever we have needed oil we have always found it and always will."" To these gentlemen the possibility of an inadequate supply of oil is as incomprehensible as the possibility of the extinction of the passenger pigeon was to the early settlers who saw flocks that hid the sun for days during their passage. The passenger pigeon disappeared within two generations thereafter, and I deem this point of view as being perhaps more vicious than that of the extreme pessimist. It seems to me it is nothing less than improvidence lulling us into a false sense of security. There is an old proverb to the effect that ""The Lord helps him who helps himself."" I believe that we shall solve the oil problem, but I do not think it will be solved by vague optimism. It is going to call for our most energetic efforts and I believe we shall have to do a lot of ""helping ourselves."""

Oct 1, 1920

By A C. Chieregati, A Heberle, F L. S P Villanova

Since the publications of Gy’s initial work, many authors have discussed the approaches to estimate the variance of the fundamental sampling error (FSE). Experimental tests suggested by Pitard and François-Bongarçon determine the sampling parameters K and a to calibrate Gy’s formula. The heterogeneity test and the sample tree method are well known and broadly used for many commodities. However, prior to the analysis, the collection of a representative sample is an intriguingly difficult task. The composite for the heterogeneity tests often consists of run-?of-?mine material or processed ore on a conveyor belt. In most cases the final sample does not have enough mass, mixes different geological units, represents a rare blend and does not characterise the deposit. In order to obtain a reliable composite for trace elements and low-grade ores, sampling practitioners suggest at least half a ton of material.To prevent the common representative pitfalls in the FSE, this case study focuses on a single gold-?bearing geological unit collected in situ. With this unit being structured by the mine geologists, but with the interaction between engineers and chemists, it was possible to validate the reconciliation suggested by Pitard (2015). The heterogeneity test and the sample tree method were performed using 500 kg of a smoky quartz from a single geological domain and the results were compared to Gy’s formula. The logging practice by the geologists was modified, emphasising the definition of the size of the gold nugget or its cluster, number of grains and association. Finally, a mineralogical study was conducted on the geological unit to define the liberation factor. All the information is compiled in this paper, showing the need to fully understand the mineralisation to correctly define representative samples and proper analytical techniques.CITATION:Villanova, F L S P, Heberle, A and Chieregati, A C, 2017. Heterogeneity tests and core logging – a final reconciliation, in Proceedings Eighth World Conference on Sampling and Blending , pp 107–114 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By R. M. Graves, C. B. McKenzie, D. Barbour, D. W. Desnoyers

"Abstract -The prospective Tulks volcanic belt hosts five significant massive sulfide deposits, Tulks Prospect, Tulks East, Jack's Pond, Daniel's Pond and Victoria Mine, as well as numerous showings and indications throughout its 70 km outcrop length. Regionally, the 498 Ma sequence consists dominantly of felsic pyroclastic rocks and flows with interbedded mafic volcanic units and fine­ grained sediments, commonly graphitic. Contemporaneous granitoid rocks occur in the south half of the belt. Rocks usually display a strong NE-SW, steeply dipping, penetrative foliation and other shear-related high-strain fabrics. Facing directions are normally northwest, although there is local evidence of folding. Sulfide bodies and their alteration systems are deformed and shape-modified in the style of ambient strain.The Tulks, Tulks East and Jack's Pond prospects appear to occupy a similar stratigraphic level, on or near the contact between a thick felsic pile and an overlying broad, conductive package of graphitic sedimentary rocks. AU are pyritic deposits with well-developed footwall alteration systems. The Tulks prospect comprises four polymetallic lenses totalling 750 000 t. Three lenses constituting more than 6 000 000 t of sulfide mineralization are indicated at Tulks East but only the 210 000 t ""B"" lens contains significant base metals. Jack's Pond consists of a very extensive, zoned alteration complex in which four lenses of massive to semi-rnassive pyrite + chalcopyrite are known.The central part of the system, characterized by Mg chlorite and carbonate, is enveloped by pervasive sericitization and capped by intensely silicified and pyritized volcanics. The sulfide lenses are interpreted as part of the footwall zone and are beneath that part of the system most likely to host polymetallic massive sulfides.Daniel's Pond differs from the other prospects in such fundamental ways as metal content, associated alteration and structural setting. The deposit comprises strongly tectonized, Ag-rich, Zn-Pb mineralization distinguished by a pronounced Ba-As-Sb signature. Mineralization is confined to a narrow, north-south high-strain zone which separates unstrained mafic volcanic rocks to the east from well-foliated felsic rocks. The deposit Jacks an extensive alteration halo and at its north end is associated with a lens of barren, undeformed massive pyrite.The Victoria Mine deposit, the most cupriferous of the five, is related to a moderately dipping structure that separates well-foliated Tulks volcanic rocks from an overlying, Jess deformed volcanic­ sedimentary sequence that may be as young as 462 Ma. The structure is also the locus of black chlorite, dolomite and quartz alteration. Structurally remobilized precursor sulfide mineralization is one possible source for the deposit."

Jan 1, 1993

By J. J. Benitez

MIBC (methyl-isobuthyl carbinol) was previously shown to enhance significantly sylvite flotation when used at the stage of preparation of amine dispersions. In this paper Atomic Force Microscopy (AFM) is used to study the effect of MIBC on deposition of octadecylamine (ODA) on the surface of mica. The AFM images indicate that amino terminated, and therefore hydrophilic, deposits of ODA are observed on the mica surface in the ODA dispersions free of MIBC. In the presence of MIBC a methyl terminated (hydrophobic) monolayer is obtained on the mica surface. The transition between the monolayer and bilayer phases is due to the presence of MIBC. Experiments carried out in distilled water reproduced the results obtained from the brine. Working in pure water instead of brine simplifies the preparation conditions and the analysis by AFM.

Jan 1, 2006

By A. H. Onur

Spontaneous combustion of coal is a significant hazard in underground coal mines. It causes serious problems for miners for many years after the fact. It threatens workers? lives and causes economic losses for companies. It disrupts coal production and makes it necessary to abandon the main drift where the spontaneous combustion occurred. Coal fires have to be prevented before they occur; otherwise they are very hard to control. Precautions thus have to be taken in potentially risky areas. For coal to spontaneously combust, it needs 3 elements: fuel, oxygen and heat. If one of them is missing, the fire cannot occur. The best way to prevent spontaneous combustion is to prevent contact between coal and air. Coating of the coal surface with an air-proof lining material would be a practical and useful solution to prevent spontaneous combustion of coal. In the scope of this study, a lining material for coating the coal surface was designed at laboratory conditions. Lining material to be used for preventing coal fires should be airproof, cheap, sufficiently strong, have low rebound, be water- and heat-resistant, and easily obtained and applied. It should also be safe for human health when in contact with mine ventilation. By considering these obligations, 3 kinds of gypsum (plaster, satin plaster, molding plaster), as well as lime, cement and fly ash and different mixtures of these materials were applied in laboratory conditions to form a lining material. Samples of lining material were subjected to uniaxial compressive strength tests to determine their behavior against roof loads. Although there is no need to carry any roof load, the lining material has to be sufficiently strong to stay in place on the applied surface. If the lining material is broken, coal and oxygen can react again. Air permeability and curing time of the mixtures were also tested in laboratory conditions. Then the tested mixtures were applied on a wall with a pump to test the applicability of mixtures. After all tests were performed in laboratory, the most suitable mixture was determined as the optimal lining material to prevent coal fires.

Aug 1, 2013

By Ángel Nuñez-Meza, Juan Alfaro-Bernedo

La intención del trabajo reportado en este artículo es la de superar las limitaciones que conlleva no trabajar con modelamiento previo, base de datos y un enfoque sistémico. En atención a esta idea, el estudio desarrolló un software para dos circuitos (directo e integral). Como resultado, se recomienda desarrollar un software integral de toda la planta concentradora —chancado, molienda, flotación y eliminación de agua— con diferentes tipos de circuito, en un solo sistema (enfoque holístico); además de migrar a un modelo de servicio en la nube, con el objeto de poder contar con completa disponibilidad.

Sep 30, 2019

By W. G. Stevenson

With the author's background of extensive experience, this paper delineates the role of the prospector in modern-day exploration programs. The stages in the development of a prospect to a producing mineral district are outlined, and examples are given from the Ross River area of the Yukon Territory and the Peachland and Highland Valley areas of British Columbia.

Jan 1, 1970

This report is the 21st in a series summarizing research and technologic work on coal and related investigations by the Federal Bureau of Mines - the Chard of the series published on a calendar-year basis 2/ Subject publica¬tions of the Bureau during 1956 are cited, and pertinent Bureau work is described briefly. The most effective method of conserving our important coal reserves is through improved technology of production and utilization. Associated problems form the program of the Bureau.3 4 5 6/ Potential production is depend¬ent on a knowledge of the quantity and quality of the reserves, and the Bureau continues to contribute information on this subject. Many problems are being studied that relate to improvements in current production, including mining methods and health and safety measures. Preparation of mined coal is necessary for its most efficient utilization. Preparation by conventional methods is being studied, as well as the development or new methods. Fundamental studies on the structure and properties of coal are necessary to insure full advantage of the special qualities of different coals. Controlling factors in the efficient use of coal in combustion, carbonization, gasification, and direct and indirect hydrogenation of coal are being studied continuously, and new processes are being investigated. The many advances in all these fields are discussed.

Jan 1, 1959

By J. B. Salsman

As part of the research effort on investigating the effects of microwave energy on the chemical and physical properties of minerals and ores, the U.S. Bureau of Mines (USBM) Tuscaloosa Research Center has conducted research to measure the dielectric properties of these materials. The objective was to establish a reliable database for use in predicting the effects of microwave heating on a wide range of minerals. The dielectric constants and loss factors of minerals, commonly referred to as the dielectric properties, were determined utilizing the theory of microwave propagation through an open-ended, air-filled coaxial line that was terminated at its open end with the particular mineral under investigation. In this phase of microwave research, the USBM measured the dielectric properties of powdered minerals with medium to high electrical conductivities in the frequency range of 300 MHz to 3 GHz and as a function of temperature from 25 to 325 °C. Since the minerals were prepared as powders, techniques were used to relate the measured dielectric properties of the powdered minerals to the dielectric properties of the mineral at its theoretical or natural density.

Jan 1, 2010

By P. A. Boeck

(San Francisco Meeting, September, 1915) THE thermal insulation of high-temperature equipment for industrial purposes is a subject that has not received from engineers and designers the attention its importance deserves. This may be attributed to a number of causes: In the first place, heat flow is a rather difficult factor to measure under the working conditions of an industrial furnace, and until the comparatively recent introduction into certain operations of the heat balance sheet, with a systematic attempt to account for the discrepancies in the totals, the various causes of heat losses and the reasons for their existence were not brought to light. Moreover, such rapid advancement and radical changes in the design of equipment, especially in metallurgical lines, have occurred that practice has apparently outdistanced the theory of design. In the modern tendency toward greatly increased size of units, effort has seemingly been made to utilize the heat of fuel gases without proper. attention having been paid to conserving heat energy and confining it strictly to the points of maximum activity. The systematic study of the thermal properties of structural materials, which is being carried out by various government bureaus and also by a number of technical societies, is forming the basis for more intelligent and consistent work in the economically important subject of prevention of fuel waste.

Jan 8, 1915

By D. Ling, Santos. R. M., T. Van Gerven, M. Guo

The valorization of alkaline waste materials from thermal processes utilizing intensified mineral carbonation routes is investigated. The principal advantages of this approach are the chemical stability and storage safety of mineral carbonates, the opportunities for process integration presented by the technology, and the potential for conversion of low-value materials into useful products. Treatment and disposal of steel slags are a costly burden on steel plants. Sustainable solutions for Argon Oxygen Decarbonisation (AOD) and Continuous Casting (CC) stainless steel slags and Basic Oxygen Furnace (BOF) steel slag are desired. An integrated on-site mineral carbonation approach is envisaged as a favourable solution.

Jan 1, 2011

By T. D. Moore

Methane emission from two surface gob-degasification boreholes was measured by the Bureau of Mines. The investigation took place during mining of a 3,200-foot longwall panel in the Lower Kittanning coalbed in central Pennsylvania. The first hole was 500 feet from the start of mining, and the second hole was 2,200 feet. The first hole went on natural draft as soon as the longwall face passed it. This caused the methane flow in the return entries to drop 75 pct. In the 6 months required to complete the panel, the two holes emitted 69 MMcf of methane in varying percentages of concentration in air. In 3 years, the holes emitted a total of 150 MMcf of methane.

Jan 1, 1976

By T. C. Eisele

The separating efficiency of a flotation column is largely limited by the degree of backmixing of tailings into the froth zone, and its recovery is limited by the degree of short-circuiting of feed to the tailings. Current columns are typically made very tall, on the order of 30-40 feet, in order to limit the effects of backmixing and short-circuiting. These effects can also be reduced in a much shorter column, provided that the flow in the column approaches plug-flow. In this work, horizontal baffles were shown to improve the performance of a 6-foot tall laboratory-scale flotation column treating a difficult-to-clean, heavily oxidized coal. Tests with variation in the position of the baffles showed that for the greatest benefit, baffles are needed both above and below the feed inlet. Tracer tests with a fluorescent dye water tracer showed that the addition of the baffles reduced the amount of feed water entrained into the froth at any given coal recovery.

Jan 1, 1994

By WM. HUFF WAGNER

Computations and allowances for mine depletion for Federal income tax purposes depend upon the meaning of certain terms in the pertinent provisions of section 114(b) 4 of the Internal Revenue Code. Unfortunately, but one of these terms is defined in the Code. Congress left it to the Commissioner to define the other terms in the Regulations. Even though the Commissioner, through his staff, labored long and earnestly to draft these definitions they have not been satisfactory to the mining industry, because the definitions in the Regulations and the interpretation placed thereon by the Commissioner do not state what the industry believes to be the clear and obvious intent of Congress. Consequently serious and prolonged disputes, unduly delaying the settlement of Federal tax returns involving percentage depletion deductions are continually arising between taxpayers and the Commissioner.

Jan 1, 1949

By Paul D. Tomlingson

Maintenance costs in the mining industry often account for as much as 18-20% of total operating costs and with the cost of labor and materials rising, they threaten to become an even larger percentage of the total. Yet, without an effective maintenance program costs can soar beyond what they would be without a program. In other words, when production equipment is down, there is no production and no product to sell in the marketplace. This cost of downtime in lost product far exceeds the actual cost of maintenance, which is defined here as labor and materials. Thus, mine management must have an effective maintenance program to avoid downtime and meet production targets. Attaining an Effective Maintenance Program Many mine management and operations supervisors believe that an effective program is a function of how hard they push maintenance. Yet, when vital production equipment is inoperable and production is lagging, no amount of pushing helps. In actuality, maintenance has little control over its own destiny and needs support from other departments to deliver good service. Success of the maintenance program depends on gaining control of those factors that directly influence maintenance. Consider the following. Organization-The maintenance organization must be structured for maximum responsiveness to production needs. Unfortunately, some needs are immediate and many are unknown in advance. The maintenance department has little control over them. These outside influences limit the department manager's ability to control his own organizational structure. Preventive maintenance procedures-Routine lubrication, equipment inspection, minor adjustments and the like are controlled mostly by maintenance. Yet, scheduling preventive maintenance depends also on the availability of equipment controlled by other departments. Planning-The purpose of planning maintenance jobs is to ensure that the best use is made of maintenance resources. If the production department creates an environment of running repairs and emergencies, there can be little planning. Even well-planned jobs will suffer if there is less than full cooperation in carrying them out. As a consequence, the maintenance department is not blocked from planning, but the value of its planning is reduced. Scheduling-Maintenance scheduling should be a joint effort. Although maintenance does the planning, production must agree to the scheduled maintenance of its equipment. Workload-As a service organization, the maintenance department has limited control over its workload because it must consistently respond to other department's demands. At best, maintenance controls only the fixed portion of its workload-utility work, janitorial service, maintenance shop work, and assigned repetitive and preventive maintenance duties. Unscheduled and emergency work are initiated by operations. Major maintenance actions require full cooperation. Labor productivity-The effective use of labor is tied to other key functions of maintenance. These include organization, preventive maintenance, planning, scheduling, and emergency work. An area type organization, for example, can often respond more quickly to immediate needs than a centrally controlled maintenance group. Yet, area maintenance can result in lower labor productivity unless tight control is exercised. One of the advantages of a good "detection-oriented" preventive maintenance program is early discovery of problems and better opportunity to schedule corrective work in advance. Under planned work conditions, use of labor can be more productive. Complete planning and scheduling can minimize time spent on each job, increase effectiveness of supervision, and improve labor productivity. Finally, if emergency work is minimized, there are fewer delays, less lost time, better coordination, and more productive use of labor. While labor productivity is an important factor in carrying out maintenance, it also is influenced by outside factors. However, few realize the impact of being able to improve maintenance productivity. By improving the productivity of 30 men from 30% to 40%, maintenance could accomplish the same work value as if it had added 7.5 men working at 40% productivity. 30 (1800) (40%) = 21,600 man-hr/yr 30 (1800) (30%) = 16,200 man-hr/yr Difference = 5,400 man-hr/yr 1800 (40%) 7.5 men Leadership-The maintenance department can have significant control over its own leaders, the front-line foremen, but they must

Jan 12, 1982

By D. M. Fritz

Environmental experts face large and rapidly-increasing volumes of raw data obtained from environmental monitoring stations. These professionals must compile and analyze the data in a systematic manner to cost-effectively understand and minimize the impacts of mining. The shift toward desktop computing, combined with the downsizing of company staffs, has now more than ever created a demand for a modern, PC-based application for the storage, retrieval, analysis and presentation of environmental data. This paper discusses the general requirements of such a system, and points out specific ways in which such industry-specific software can provide convenient and useful access to the data. The software used to illustrate these features is the HydroDat program, developed by Western Water Consultants, Inc.

Jan 1, 1996