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From the viewpoint of mechanical efficiency, charges should be fully coupled and, upon detonation, should just fail to break the rock in compression. But because mining thrives on its cost-effectiveness rather than its mechan- ical efficiency, the explosive which generates maximum energy per $ should generally be used, even though the mechanical efficiency of this explosive's detonation products may be sub- optimum. Wherever possible, each charge should have a length:diameter ratio of about 20 or more and should shoot to a concavely biplanar free face that is both parallel and reasonably close to the blasthole. Success in obtaining parallel effective faces often demands the drilling of angled blastholes and, hence, will require intensified research and development efforts by drilling manufacturers, especially where hard strong rocks are encountered. Blastholes should be drilled on equilateral triangular grids and fired in a Vl or shallower V-type sequence using inter-row delays which ensure that good pro- gressive relief of burden is achieved. The conventional method of calculating Se/Be values (on the basis of planar effective faces) is often invalid.

Jan 1, 1986

By Bennet A. G

An overall review of the selection of rock strength and deformation characteris- tics for the design of the Melbourne Under- qround Rail Loop (MIJRL) rock tunnels is presented. Particular emphasis is placed on aspects of in-situ testing, including large diameter plate bearing tests. Material on the interpretation of test results for use in the design of the tunnel linings and openings is included, with a brief discus- sion of desiqn methods.

Jan 1, 1981

By R. A. Burns

Kaolin clay has a broad range of applications with the paper market representing the largest end-use. Calcined kaolin finds application in paper, paint and plastics primarily for its high brightness and light scattering ability. It is well known as an extender for TiO2. Meta-kaolin possesses a unique set of physical and chemical characteristics finding use in both traditional kaolin/calcined kaolin markets as well as other unique applications. This paper discusses the intricacies of manufacture and the key physical and chemical properties of meta-kaolin. Specific applications and the relationship of the physical/chemical properties to end-use performance are discussed.

Jan 1, 2002

By J. A. King, D. R. Weir, P. C. Robinson

The complex mineralogy of the Porgera resource has a pronounced effect on process selection for the recovery of refractory gold and silver. Intimate association of gold with pyrite necessitates a high degree of sulphur preoxidation to achieve acceptable levels of gold recovery. Acid pressure oxidation has been demonstrated to be the only commercially proven process capable of achieving the required level of pyrite oxidation. Gangue mineralization dictates preconcentration of the sulphides to limit the acid consuming capacity and carbon dioxide generation during oxidation. However, the relationship between concentrate sulphur grade and gold recovery to concentrate ultimately governs the optimum degree of sulphide preconcentration. Minipiloting of the preconcentration and oxidation stages of the Porgera flowsheet are described. The influence of these processes on subsequent recovery of precious metals together with the technical and economic necessity of concentrate pretreatment prior to oxidation are discussed.

Jan 1, 1987

By Oscar Campoblanco

El presente texto describe el nuevo software FMMS (Ferreyros Maintenance Management Software) que ofrece Ferreyros como soporte de sistemas al equipo de servicio de monitoreo centralizado de equipos de mineros. Este sistema trabaja combinando las herramientas más comunes de monitoreo de condiciones usadas en una estrategia de mantenimiento basado en condición. Asimismo, se incluye herramientas de administración de gestión como la de reparación de componentes, la cual ofrece el nivel de integración requerido del administrador con su taller de reparaciones y el plan de acción, que está enfocado en mejorar la capacidad del seguimiento del analista de mantenimiento preventivo.

Sep 19, 2006

By Liu Z. C

Evans' theory for chisel shaped picks is well known in the field of rock cutting technology. It has been widely accepted as a good mathematical description of how coal and other rocks break under the action of a simple wedge or chisel. Subsequently, Evans proposed a corresponding theory for pointed shaped picks. Theory along with experimental evidence from the laboratory has consistently shown that chisel picks are more efficient than pointed picks. However despite such evidence, pointed picks continue to be the preferred shape in most practical cutting applications. Evans' theory for pointed picks was developed in an attempt to shed light on this apparent incongruity. The theory although predicting forces of the right order was found to be deficient in several respects. This paper examines Evans' theory for pointed picks and proposes changes to it, which brings the theory much more into line with measured data. The issue of the relative efficiencies of chisel and pointed shaped picks is also examined on a theoretical basis and the apparent incongruity is Resolved.

Jan 1, 1995

By C. E. Birchenall, J. R. Stubbles

ThE equilibrium between lead, lead sulfide (PbS), and atmospheres of H2 and H2S has been determined previously by Jellinek and Deubel,' and SudO.' Blbem and Kroger3,4 used Jellinek's data to calculate the sulfur dissociation pressures of PbS crystals (of

Jan 1, 1960

By L. A. Roe

Magnetic separation occupies an attractive position in the field of ore beneficiation. It is a simple yet effective method, used for some 150 years and steadily growing more important. This type of beneficiation orginated in 1792, when William Fullarton was issued a British patent covering the separation of iron ore by magnetic attraction. What is magnetism, and why are some materials capable of being magnetized and others not? The study involves many unknowns, and even a partial answer to these questions would be a dissertation in solid state physics and perhaps other fields of science. But the last two decades have revealed basic facts as to why certain materials are magnetic and what happens to them when they are magnetized.

Jan 12, 1958

By B. J. Scheiner

A ferrous chloride-oxygen leaching system was investigated by the Federal Bureau of Mines to determine its effectiveness for recovering copper and silver from a tetrahedrite concentrate that had been pretreated to remove a majority of the antimony. The pretreated concentrate contained coppers, silver, lead, zinc, antimony, and arsenic. Parameters affecting metal extraction (such as temperature, pressure, amount of ferrous chloride, and initial hydro-gen ion concentration) were studied. Copper extraction of 98 pct was achieved by leaching 4 hours at 40 pounds per square inch gage (psig) and 100° C. Copper was recovered from leach solutions by cementation with iron, and the resulting ferrous chloride was recycled. Leaching the residue with cyanide followed by electrowinning recovered 99.7 pct of the silver. Iron, antimony, arsenic, and sulfur reported to the tailings.

Jan 1, 1978

By E. R. Bollinger, N. S. Tanious, R. D. Beckett

The US Bureau of Mines developed hand-made, steel-fiber-reinforced concrete (SFC) blocks for building mine cribs. To ensure wider usage of these cribs, US Steel Mining Co. initiated a joint development and evaluation program with Burrell Construction Co. to mass produce SFC blocks of reasonable dimension, weight, and cost. Small specimens and full-size cribs were evaluated to determine their compressive strength and post failure characteristics. After testing and adjusting of various concrete mixtures, a final formulation was selected that gave a nominal crib strength of 22 MPa (3200 psi) and a nominal modulus of elasticity of 6.9 GPa (1.0 x 106 psi.) These SFC cribs can support 6.4 times as much as a wood crib with the same load-bearing area. The SFC crib was proven to be an economical and effective roof support system through various underground installations.

Jan 1, 1987

By Raymond E. Krauss

The McLaughlin Mine is a world class epithermal gold deposit located in the coastal thrust fault of Northern California, U.S.A. Homestake adopted a proactive strategy in the permitting of the Mine. Extensive environmental baseline studies were undertaken. Engineering and process alternatives were evaluated for environmental impact along with other factors. A unique pressure oxidation process was selected. Screening studies were conducted as a basis for the selection of waste rock and tailings disposal sites. Project engineering and permitting were fast tracked. Construction required eighteen months, and the first gold bar was poured in March of 1985, six years after the initial discovery. Project facilities are designed and operated so as to minimize environmental impacts. A comprehensive monitoring program demonstrates permit compliance. Reclamation of the site is ongoing throughout the Mine's twenty year life. Nonmined lands are managed to maximize wildlife habitat value.

Jan 1, 1990

Sec. 1. The membership of the Institute shall comprise six classes, namely: 1. Members; 2. Honorary Members; 3. Senior Members; 4. Associates; 5. Junior Members; 6. Rocky Mountain Members. All shall be equally entitled to the privileges of membership, excepting that no member of any class whom residence shall be outside of the United States of America, except those residing in Mexico and Canada, shall be entitled to vote. SEC. 2. Members: A person to be eligible for election or transfer into the claw of Member must be at least 27 years of age and must have had at least six years' employment in the practice of engineering, mining, geology, metallurgy, or chemistry, during at least three years of which he must have held positions of responsibility in one or more of these fields. This shall not apply to Rocky Mountain members.

Jan 1, 1936

By F. Ames Smith

Offshore oil and gas production operations have moved from water depths of about 50 feet in 1948 to the present record depth of 340 feet. Although mobile drilling rigs are widely used for exploratory drilling, most development drilling and production operations have been conducted above water from the decks of fixed, bottom-founded platforms. Increasing water depths have caused problems associated with design and construction of these platforms and with laying of pipelines, but not so much with other activities. After a platform is installed, drilling, production, and maintenance operations are similar to those onshore and are relatively unaffected by water depth. Events of 1968 indicate that offshore production may soon extend into much deeper water. These events include leasing of Santa Barbara Channel acreage in water depths over 1500 feet, and the successful drilling of a wildcat well in 1300 feet. Designs have been developed for platforms suitable for installation in water over 600 feet deep, and studies suggest they may be used in some areas to water depths of 800 to 1000 feet. Buoyant towers can probably support above-surface platforms in water 1000 feet and deeper. Although the cost of either of these platforms will be high, once installed they will permit relatively low-cost development drilling and production operations compared with estimates for subsea production systems. In some cases, savings in development drilling costs alone could pay out the platform investment.

Jan 1, 1969

By M. M. Bwalya, F. K. Mulenga

"SynopsisThe application of the attainable region (AR) technique to the analysis of ball milling is currently limited to batch data. This paper introduces the use of the technique to continuous milling.To this end, an industrial open milling circuit processing a platinum ore was surveyed. Samples were collected and later characterized by means of laboratory batch testing. On site, several milling parameters were varied systematically so as to collect data for modelling purposes. These paramters included ball filling, slurry concentration, and feed flow rate. After data analysis, a simulation model of the open milling circuit was developed under MODSIM®, a modular simulator for mineral processing operations. The mill was then simulated and the data generated was analysed within the AR framework.Initial findings reveal an opportunity to gain valuable insight by studying milling using the AR technique. From an exploratory perspective and inasmuch as this study is concerned, feed flow rate, ball size, and ball filling were identified as being pivotal for the optimization of open ballmilling circuits. Mill speed, on the other hand, had only a limited effect on the production of particles in the size range -75 +10 µm.IntroductionGlasser and Hildebrandt (1997) propounded the attainable region (AR) as a technique for the analysis of chemical engineering reactor systems. Results have since been produced and tested on both the laboratory and pilot scales. The method results in a graphical description of chemical reactions by considering the fundamental processes taking place in the system, rather than the equipment. From the plotted graphs, the process and the reactors can be synthesized optimally into a flow sheet.The use of the AR method still has a long way to go as far as mineral processing is concerned. For instance, several articles have reported the application of the AR technique to ball milling: Khumalo et al. (2006, 2007, 2008); Khumalo (2007); Metzger et al. (2009, 2012); Metzger (2011); Katubilwa et al. (2011); Hlabangana et al. (2012). Their main shortcoming has been the exclusive use of laboratory batch grinding data.To address this deficiency, Mulenga and Chimwani (2013) proposed a way by which the technique could be extended to continuous milling. In effect, the batch milling characteristics of a platinum-bearing ore (Chimwani et al., 2013) were used and scaled up to an open milling circuit. Then, with simplifying assumptions, an attempt was made to optimize the residence time of particles inside the mill. Later, Chimwani et al. (2014a) presented some optimization examples involving various milling parameters. The sequence of published articles then paved the way for the study of industrial milling systems with the AR methodology."

Jan 1, 2015

By Norman F. Schulz

The technical excellence of separation achieved in a mineral concentration process, or any other process where two constituents of any kind are physically separated from each other, is expressed uniquely and quantitatively by the Separation Efficiency: ES = (R ? Rg) where R is the percentage of the valuable constituent and Rg the percentage of the waste appearing in the concentrate. The Separation Efficiency meets all the usual requirements of a true efficiency and is independent of the nature of the process used. It can be visualized as the percentage of the feed material that, in effect, actually undergoes complete separation while the rest of the feed is distributed randomly and unchanged into the two separation products.

Jan 1, 1969

By D. L. Pitt

This paper, describing the milling methods at the concentrator of the Premier Gold Mining Co., Ltd., Premier, B. C., Canada, is one of a series being prepared by the United States Bureau of Mines on milling methods and costs in the various mining districts throughout the United States and Canada. ACKNOWLEDGMENTS The authors wish to acknowledge the assistance and suggestions given during the preparation of this paper by the engineering staff and accounting department of the Premier Gold Mining Co., Ltd., all of whom have assisted materially in gathering the data used.

Jan 1, 1933

By Clyde M. Pearce

The Lake Superior iron-mining district includes parts of the States of Michigan, Minnesota, and Wisconsin. The laws of each State provide for an industrial commission and for inspection of mines. The following extract from the General Orders on Mines, effective October 25, 1937, issued by the Industrial Commission of Wisconsin, is the only reference to the use of safety catches on mine cages or skips found in the laws and regulations in the Lake Superior iron-mining district: Order 316 - Cages for Hoisting Men. (c) Sides, Gates, and Safety Catches. ***Every cage shall be provided with safety catches of sufficient strength to hold the cage with its maximum load at any point in the event the hoisting cable should break. (d) Testing Safety Catches. The safety catches of cages and skips used to hoist men shall be kept well oiled and in good working order. They shall be tested at least once each month by tying up the cage or skip with hemp rope, lowering a few feet of hoisting cable on top of cage, then cutting the hemp rope, provided that any other system of testing, which is equally effective, may be used.

Jan 1, 1945

By K. C. Grogan

"GeneralGIANT ORE is complex, with the gold values for the most part occurring in extremely close association with arsenopyrite, stibnite, jamesonite, and a wide group of antimonial minerals locally termed 'the grey minerals'. Pyrite is the most abundant of the sulphide minerals• and minor quantities of chalcopyrite, galena, and sphalerite also occur. Pyrrhotite has been found in some sections of the mine, but to date none of it has been nickeliferous. Native gold occurs in varying amounts throughout the ore bodies.In 1944, ore dressing investigations were commenced on diamond-drill core rejects and samples of surface outcrop ore. Results soon indicated that treatment to produce satisfactory recovery of the gold values would involve fine grinding to 80-85 per cent minus 200 mesh, recovery of free gold by jigs, followed by flotation, roasting of the flotation concentrate, and subsequent cyanidation of the calcine. Proceeding from this information, the flow-sheet was prepared, plant design worked out, equipment purchased, and construction of the treatment plant commenced in May, 1947.The crushing, grinding, and flotation units of the plant were rushed to completion and commenced operation on May 12th, l.948, at 225 tons of ore per day. This rate was maintained until January 27th, 1949, when the Allis-Chalmers roaster and cyanide plants were completed and commenced operation. During the period May 12th, 1948, to January 27th, 1949, gold recovered by amalgamation was the sole source of revenue. Flotation concentrate was stockpiled pending the completion of the Allis~Chalmers roaster and cyanide plants."

Jan 1, 1953

By D. S. Kingery

Efficient transportation is necessary to complement modern mechanized mining methods. The increasing trend toward high-capacity face loading equipment has demanded equally efficient haulage methods; this has been met by increasing mine-car sizes, using larger locomotives, and increasing haulage speeds, all requiring properly installed and maintained haulage roads specifically designed for this type of traffic. The recommendations and specifications included in this circular were made to point out salient factors important to the proper construction and maintenance of track haulage roads and to serve as recommended standards for track installation and maintenance. GLOSSARY OF TERMS USED Haulageway. - The track, walkway, trolley wire, feeder lines signal end telephone lines, signals, telephones, support, and drainage of the entry referred to. Subgrede. - The base upon which the ballast is laid.

Jan 1, 1954

By G. M. Bond

Reduction of the emissions of greenhouse gases, such as CO,, is currently the subject of extensive research. A novel strategy is put forward here, based on a biomimetic approach providing accelerated deposition into carbonate form for long-term sequestration. It offers the advantages of a process that: does not require concentration of CO, from flue gases; could potentially be used in an on-site scrubber to provide a plant-by-plant solution to reducing CO, emissions; is an environmentally benign procss with an environmentally benign product; and is based on readily available, low-cost reagents (except perhaps the catalyst).

Jan 1, 1999