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By D. Bouchard, J. Langlais, A. Lemieux, N. Andrade

A concerted effort between Akan International Limited and the National Research Council of Canada (NRC) has been initiated to develop a liquid-based slurrymaking process, dubbed SEED (Swirled Enthalpy Equilibration Device) for semi-solid forming. The technology is presently entering the industrial and commercial stages, and will be used by the first customers at the end of 2006. Semi-solid processing of aluminium alloys offers many advantages in fabricating economically near-net-shape parts of superior quality. The SEED process helps to overcome problems experienced with thixocasting and especially the high cost of feedstock. The SEED process involves two main steps: 1) heat extraction to achieve a desired liquid/solid mixture, and 2) drainage of an excess liquid to produce a self-supporting semi-solid slug that is formed under pressure. The heat transfer plays an important role (enthalpy equilibrium) during the manufacture of the semi-solid slurry and its analysis is briefly described. The semisolid material is obtained using different processing times and initial conditions. The impact on the solid fraction distribution and the morphological evolution of the microstructure is presented. The influence of the SEED processing parameters (slurry preparation) and the resulting mechanical properties for the alloy A356 are also reported.

Jan 1, 2006

By Y. Huang

Corrosion of GaAs in aqueous electrolytes is a major limitation in implementing GaAs-based photoelectrochemical solar energy conversion systems, In this work, the corrosion behavior was investigated by electrochemical methods and surface analysis approaches, in both H2SO4 and NH3?H2O solutions, Open-circuit measurements showed that the cleaned GaAs surface was very sensitive to water/air, Impedance measurements for n-GaAs showed that an inductive loop only appeared at a high corrosion rate because a reaction intermediate is the oxidant for a further decomposition step in combination with chemical reaction with water, The results suggest that the same corrosion/decomposition mechanism occurred on n-GaAs in the two solutions, When the surface-hole concentration was low, the hole injection or generation process was the rate-determining step, At large reverse bias on n-GaAs, with high-hole concentration, the corrosion rate was limited by a Faradaic adsorption process, involving an adsorbed intermediate, The different surface compositions after corrosion in the two solutions can be explained by the dissolution of As(0), Further oxidation of As(0) to As(III) in NH3?H2O solution is still slow, as suggested from X-ray photoelectron spectroscopy (XPS) analysis,

Jan 1, 2005

By Igor Wilkomirsky

Professor Ralph Harris was interested in minor elements behavior in nonferrous pyrometallurgical processes. His approach always considered fundamental aspects and technological considerations for the assessment of different challenges that today are becoming critical, particularly for Andean sulfides ores, where the content of Va elements (As, Sb and Bi) has challenged available technologies. This reviews the status of control and monitoring of As in copper smelters to give a general framework for this now-common problem. Some selected results of R & D programs at the University of Concepción are presented in the field of roasting, presenting a novel proposition for flue dust treatment as an alternative to the classical hydrometallurgical processes for these type of materials. This presentation seeks to open a broad but precise discussion about the needs of research in this area with further experimental and physicochemical modeling. The pioneering visions developed by Professor Harris with his students are now a source of inspiration and an unavoidable source of information.

Jan 1, 2013

By Prodipto Ghosh

This paper is prepared as a review of existing and traditional methods related to electrical maintenance strategy. Its primary focus is to explore newer ideas and how they point the way to a more efficient and effective manner of electrical maintenance. This discussion is primarily related to large electrical distribution assets typical of heavy industry such as mining.

Aug 1, 2013

Prepare ATF Report of Theft or Loss (ATF Form 5400.5). A Report of Theft or Loss - Explosives Materials must be prepared when it is discovered that explosive materials are missing from inventory. Submit the original to the U.S. Bomb Data Center and keep a copy for your records. The form can be obtained from the ATF Distribution Center or from www.atf.gov. Although the U.S. Bomb Data Center should be notified as soon as possible, Federal law requires notification within 24 hours of the discovery. A full inventory check is also highly recommended (but not required) to locate missing explosives and to prevent future losses.

Jan 1, 2008

By Jochen Franke, Matt Bird, Thoma Perkins, Malcolm Powell, Jason Robertson, Paul Toor

zThe operation of SAG mills is variable over time due to their continually changing liner shape, mass and subsequent load motion. However, this tends to be poorly accommodated in liner design and mill control, with only limited compensation made for this influence, usually in the first few weeks after a new liner is installed. With ever-increasing ore competency, increasing energy costs and decreasing ore grades, simplified design and operational approaches that compromise the achievable mill efficiency are no longer adequate. This paper presents a methodology that has been developed to measure and account for the changes in mill performance as the liner wears. This involves monitoring all liner profiles – in other words the three-dimensional liner shape - over the life of the liner, then conducting controlled surveys at different stages of the liner wear life, and correlating the mill performance to the liner profiles. The measured liner mass is modelled to provide an ongoing meaningful load mass measure that excludes the liner mass.

Jan 1, 2012

By Z. Q. Bian

The wireline sampling originates from core drilling in rocks. The authors combined the wireline sampling technique with conventional undisturbed soil samplers, including Osterberg sampler, Denison sampler and double tube barrel, and then developed the wireline samplers of WPS, WSS and WSR models. These samplers are able to sample various soils. They reserve all the advantages of the original samplers, and moreover, they are noted with quick hoisting and lowering by wire rope. Therefore, it becomes an efficient new technique of sampling undisturbed soil from deep foundation.

Jan 1, 2010

Solid Energy New Zealand (SENZ) uses a 20+ year period for integrated planning of all its business activities. It has an ongoing program of coal resource assessment to optimise future mines within this 20 year period, using a six step resource and mine planning process. Desktop review and conceptual study at preliminary Levels 1 and 2 are based on general coal resource information. Further coal resource investigations are carried out for the more detailed evaluations in secondary assessment, prefeasibility study, feasibility study and detailed engineering from Levels 3 to 6. At Levels 1 and 2, completing conceptual planning, including preliminary resource evaluation and economic appraisal to the target cost uncertainty level of ¦33 per cent, is challenging in New ZealandÆs highly variable geological and geographical conditions. Where coal deposit geometries are relatively simple, approximate methods for determining pit limits using overburden strip ratios, seam thickness, physical boundaries, and quality cut-offs may be sufficient. Many New Zealand coalfields are however complicated structurally, with multiple seams and extensive folding and faulting. Coal seams are characterised by variable dip, thickness, and quality over relatively short distances. In the North IslandÆs Waikato coalfields, coal is typically overlain by weak sediments and clay rich strata that necessitate very flat cut and fill slope angles. The proximity of these deposits to major infrastructure (including towns, highways and rail lines), significant environmental features such as the Waikato river and lakes, and valuable dairy farmland, add further complexity. Traditional preliminary mine planning techniques applied in these conditions are insufficient. Pit optimisation software, widely used in the metalliferous mining industry since the 1980s, offers the ability to analyse many more specific factors affecting pit limits, mine layouts, and economics, with more rigour and for a much larger number of scenarios, than traditional methods allow. SENZ therefore decided to adapt and use æWhittleÆ pit optimisation software for Level 2 analysis of several Waikato opencast prospects. This paper describes this work.

Jan 1, 2005

By Chas. F. Jackson

This paper is published as a progress report for the first half of 1929 on the study of wining methods and costs in the Eastern and Central States. Data obtained from 25 mines using open-stope methods are correlated and summarized. Some of these mines have been described in considerable detail in reports already published as Information Circulars. In addition to the published reports on individual mines, considerable data have been obtained from other mines which were visited and studied during the course of the investigation. Many of these mines will later be described in detail in separate papers, and when the field has been covered in this manner it is planned to issue a bulletin on open-stops methods of mining which will amplify the subject matter of the present paper. Definition of ?Open-Stops?. - The term "open-stopes" as employed by the Bureau of Mines is applied to all naturally supported stopes; that is, stopes in which the excavated ore is not replaced by support of an artificial nature other than preps or stulls and in which the ore or (and) capping are not caved during the active life of the stopes.

Jan 1, 1931

By William Ian Wark, Alwyn Birchmore Cox

DIFFERENT parts of the world in which mineral separation by flotation is practiced experience vastly different natural temperatures, and in some districts there is a big difference between summer and winter temperatures. It will be shown in this paper that the temperature is of considerable importance where it is desired to separate pyrite or arsenopyrite from other minerals. It is probable that some of the differences obtained in the flotation of these minerals at plants working under otherwise similar conditions are due to temperature variations. The influence of temperature on the flotation of galena, chalcopyrite and sphalerite by xanthates is less marked than its influence on pyrite flotation. EXPERIMENTAL METHOD The methods used have been described previously.1-4 In each test the clean mineral specimen was immersed in a solution prepared by adding the reagents in the following order: (1) sodium carbonate and hydrochloric acid as necessary to buffer the solution and to give approximately the pH value desired, (2) sodium cyanide, (3) copper sulphate, (4) ethyl xanthate, followed by (5) a final adjustment of pH value. After ½ hr. the mineral was tested for a xanthate film by bringing a bubble of air into apparent contact with the submerged polished surface. If true contact (spreading) was not obtained within ½ min. and after cleaning the surface by wiping with a small linen pad, it was concluded that the adsorption of a xanthate film had been prevented. Following the method already described (ref. 2), curves have been constructed such that for a solution ' composition corresponding to any point below the curve, contact between mineral and air is possible, whereas for a solution composition corresponding to any point above the curve, contact is impossible.

Jan 1, 1938

By P. Mercille, M. F. Nasmyth, J. G. Cooper

The turn of the century sees considerable activity in the zinc industry for the replacement or expansion of existing cellhouses, and the building of new cellhouses as part of new zinc projects. Aside from the cellhouse technology itself, numerous engineering and construction issues play a major role in the success of a project for replacing or building new cellhouses. The purpose of this paper is to bring to light and to address the engineering and construction factors which go beyond the selection of a cellhouse technology and which remain of key importance in implementing such projects. In addition, some implications of these factors for project costs will be illustrated.

Jan 1, 2000

By Arkady Senchenko

At present, there are different traditional and modern methods for ore grindability evaluation. The correct and rational approach to sampling, testing methods and mill sizing enables one to design a workable technology. This paper contains TOMS institute experience in different grinding indices determination over the last 7 years (SAG Design Test, BWi, CWi, RWi, and other). Mill sizing examples and circuits modeling for the projects in Russia and Kazakhstan are considered. Keywords: ore grindability, SAG Design Test

Sep 1, 2012

By W. M. Husslage

The permeability in the blast furnace shaft is adversely affected by low temperature reduction degradation of sinters. The fundamental cause is an expansion of the iron oxide phase resulting from reduction of hematite to magnetite. The present study showed that expansion behavior during the hematite / magnetite reduction step and the resulting microstructure are strongly influenced by the reduction temperature (viz. partial oxygen pressure), the reducing agent and the nature of the hematite. The reduction rate is of minor importance. A reduction mechanism is proposed, explaining the dilation behavior and the magnetite microstructure. The results can provide better insight into reduction degradation behavior.

Jan 1, 1998

By Oliver Bowles

Since 1922 when the Bureau of Mines issued a report2 covering the slate industry in detail, changes in technology have taken place which have an important bearing on the industry. The present paper comprises a record of these changes. Though the value of slate, for roofing, structural, blackboard, sanitary, and electrical uses is generally recognized, it has many competitors. To meet this constantly increasing competition producers are promoting economies in manufacture, and improving processes, thereby lessening costs of production, and are placing on the market products of the highest possible quality, thus creating satisfaction and confidence on the part of the user. This endeavor to place the industry on a better basis, both as regards processes and products, is shown in the recent developments in technology which are presented herein. Valuable assistance in obtaining data for this paper was given by W. S. Hays, secretary of the National Slate Association, N. M. Male, president of the National Slate Association, and Robert Notvest, consulting engineer, Cleveland, O.

Jan 1, 1926

By Shubin Wang

Copper(II) and nickel(II) are often recovered from ammoniacal alkaline solutions by solvent extraction using hydroxyoxime extractants: both copper(II) and nickel(II) are extracted from ammoniacal alkaline solutions and, from the loaded organic phase, nickel(II) is selectively stripped with a dilute acid followed by copper(II) stripping with an acid of higher concentration. Since a small portion of ammonia is co-extracted with copper and nickel, the extracted ammonia should be scrubbed using a dilute acid before metal stripping. In the present study, a mechanistic model has been developed in order to support design and control of this process. The equilibrium distribution ratios of copper(II), nickel(II), and ammonia at 298 K using LIX® 84-I (active component, 2-hydroxy-5-nonylacetophenone oxime) as the extractant are successfully correlated by considering the relevant equilibria. Based on these results, quantitative prediction of equilibrium distribution ratios in the process has been made possible, and suitable conditions for the efficient separation of copper(II) and nickel(II) are discussed.

By J. B. Clemmer

Fluorspar is one of the most important nonmetallic minerals and is used extensively in the metallurgical, ceramic, cement, and chemical industries. The steel industry consumes most of it, but as the Mineral is the chief source of fluorine, it is becoming increasingly valuable to the chemical industry in the production of fluorine compounds The development of nontoxic organic fluorides for use as refrigerants in mechanical refrigeration and air-conditioning units illustrates the increasing use of fluorspar in the chemical industry. Most domestic flurospar comes from deposits in the Illinois-Kentucky district, which centers around Rosiclare, Ill. About a dozen companies operate in the district, which comprises parts of Pope and Hardin Counties in southern Illinois and Crittenden, Livingston, and Caldwell Counties in western Kentucky. According to the latest available statistics, this district supplied 1/5,960 short tons of fluorspar in 1937, compared with the total domestic production of 181,230 tons. Imports totaled 37,063 tons.

Jan 1, 1939

By Seedsman R. W

Good roads are essential in moving men and materials to and from the underground workplace. Coffey Partners International Pty Ltd (Coffey) has recently completed a underground coal industry funded project on underground mine road construction and maintenance. This paper discusses practical approaches to construction and maintenance of underground mine roads using transferrable civil technologies and innovative techniques. Mine pavements are generally low-cost (relative to civil roads), constructed to varying standards using locally available materials to best meet the mobility needs of the mine. Performance of pavements is thus largely dependent on the environmental conditions, quality of the available road making materials, maintenance policies and available resources. The paper will detail `what causes bad roads?' in various underground environments, available management strategies, construction and water control techniques, road maintenance and vehicle considerations.

Jan 1, 1995

By William L. Swager

This is the second in Mining Engineering's series of articles on sources, uses, production, and conservation of strategic minerals. "Cobalt" first in the series, appeared in February 1951.

Jan 5, 1951

By L. M. Turner

Perlite is a unique mineral that upon heating expands to about twenty times its original volume. Mining is by open pit method. The processing cycle involves crushing, screening and sizing the ore. An on-site quality control facility at the Manville Products No Agua mine exerts a high degree of control over every phase of the operation from blasting to finished product.

Jan 1, 1985

By D. L. Soreck

The hazards to the public posed by abandoned mine shafts are well documented. As private development encroaches on previously mined areas, the potential for fatalities and serious injuries from abandoned mine shafts increases. The U.S. Bureau of Mines has conducted research into cellular concrete as a material for sealing these openings. The current work involves testing the characteristics of cellular concrete before and after it had been pumped or dropped from different heights into a simulated mine shaft. Cellular concrete was pumped vertically up to and subsequently dropped from heights of 18 and 37 m into concrete forms. Wet density measurements were made at multiple sampling points in the test circuit. Air content determinations and uniaxial compressive strength testing were conducted. Research results showed significant loss in air content and changes in the characteristics of cellular concrete during pumping or dropping from various heights. Recommendations on effective use of cellular concrete for sealing abandoned mine shafts are made.

Jan 1, 2010