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By J. Don Scott

Analytical predictions of the rate and magnitude of settlement of deposited oil sands tailings slurries generally overestimate how fast pore pressures will dissipate. Field deposits of nonsegregating tailings to mature fine tailings show continued high pore pressures near the surface which impede surface reclamation. In geotechnical analyses which predict the consolidation behavior of soft soils a finite strain theory is used. Effective stress-void ratio and void ratio-hydraulic conductivity relationships determined from laboratory large strain consolidation tests, are used in the finite strain predictions. This theory, however, cannot predict the full range of sedimentation, consolidation and pore pressure dissipation which occurs in large scale deposits of thixotropic tailings slurries. A new large strain consolidation model which assumes that the creep rate of the slurry exceeds the pore pressure dissipation rate is being investigated. This model is relevant for rapidly deposited, low permeability thixotropic slurries where the upwards drainage path increases by several meters a year, such as, in oil sand fine tailings ponds and nonsegregating tailings deposits. The model will be verified by analyzing the 10m high column of fine tailings at the University of Alberta which has been monitored for over 20 years and in which the excess pore pressures are still very high.

May 1, 2004

By Pengfu Tan

A program ?SlagVis? has been developed to simulate the liquidus temperature, phase compositions and viscosities of ZnO-CaO-SiO2-Al2O3-?FeO? slag, such as Imperial Smelting Furnace (ISF) slag and lead blast furnace slag, combined with F*A*C*T slag database and the mathematical model of slag viscosities based on a modified Urbain formalism. The modeling results have been validated by a number of measurements. The effects of slag compositions on viscosities of ISF slag and lead blast furnace slag have been simulated and discussed.

Jan 1, 2005

By James P. Rider, Charles D. Taylor, Edward D. Thimons

Research was conducted to investigate how ventilation of a mining face is affected when scrubber flow is greater or less than intake flow. Tests were conducted in a full-scale surface test gallery built to simulate a mining entry with a continuous mining ma- chine at the face. Methane gas was released at constant flow at the mining face. Gas measurements taken at six locations near the face were used to evaluate how well the face was being ventilated. Increasing scrubber flow resulted in lower methane levels even when scrubber flow was much greater than intake flow.

By Steve Custer, Tim Kahl, Sue Parker

"The primary objective of the Barrick Goldstrike expert system is to achieve the desired liberation size for the autoclave circuit while maximizing throughput. In addition, when downstream limitations (autoclave circuit or others) restrict the milling circuit tonnage the expert system further improves grinding product size. Since its implementation, the expert system has provided expected throughput improvements while improving or maintaining circuit performance.Barrick Goldstrike and MinnovEX Technologies Inc. teamed up to install an expert system to control Line I and I1 of the autoclave grinding circuits. The dissimilar equipments of the two grinding circuits coupled to different production objectives, skepticism among operators, and the variability of the ore types processed in each line challenged the implementation.To ensure implementation success, Barrick Goldstrike dedicated four administrators full time to the project. The system administrators included two metallurgists, a process control engineer and a mill trainer. As usual, the control room operators were the experts who provided the operational logic for the foundation of the control system. The administrators and all eleven of the control room operators signed off on acceptance of the system. Current online utilization is 95%.INTRODUCTIONThe grinding circuit for Barrick Goldstrike’s autoclave process consists of two SAG Mill Ball Mill lines. Line 1 grinding circuit is comprised of a 22 by 8 foot, 2500 horsepower Allis Chalmers (AC) variable speed SAG mill, followed by a 12.5 by 14 foot, 1250 horsepower AC ball mill, and a 13.5 by 18 foot, 1800 horsepower Dominion ball mill in parallel. SAG mill recycle from the primary discharge screen (+5/16 inch) is processed through a 1352 Nordberg Omnicone crusher (4.5 foot). A secondary SAG discharge screen (+1/8 inch) closes the SAG circuit. The ball mill circuit is closed with 6 Krebs super D20 cyclones. Line 2 grinding circuit is comprised of a 24 by 12 foot 4000 horsepower Fuller variable speed SAG mill followed by a 16.5 by 30.5 foot 5000 horsepower Fuller ball mill. SAG mill recycle from the primary discharge screen (+5/16 inch) is processed through a 1560 Nordberg Omnicone crusher (5 foot). A secondary SAG discharge screen (+1/8 inch) closes the SAG circuit. The line 2 ball mill circuit is closed with 12 Krebs super D20 cyclones. The underground Meikle ore is typically fed through Line 1. Achieving the desired product size is critical for successful processing of Meikle ore. Open pit Betze ore is fed to Line 1 when Meikle ore is unavailable. Line 2 processes Betze ore exclusively. Throughput is maximized when processing Betze ore as the product size is less critical. The products of these two circuits are combined as feed to the autoclave circuit. The ore types and the autoclave circuit demands determine the required grinding circuit product size and maximum combined mill feed tonnage."

Jan 1, 2001

Early American history is filled with records of the search for and extraction of minerals-a Northwest passage to the treasures of the Indies-an overland route to the goldfields of California. Mining and its associated minerals industry have heralded advancing civilization throughout the ages. The two basic resources on which we all depend for our food, clothing, shelter, and other comforts are agriculture and minerals. Our endowment and how we use it; the spirit and industriousness of our people; our form of social organization all converge to make up our standard of living-our way of life.

Jan 1, 2012

By Y. Bai, J. J. Liu, D. Q. Li, S. Z. Liu, X. T. Wang

"This paper presents the results of an industrial test using 8 t/d of Baotou concentrate (50% REO) of a clean metallurgical process, which includes: 1. Roasting with H2SO4 at low temperature (220~260 0C) in a batch roasting furnace followed by water leaching to obtain a leach liquor as feed with a yield of >95% RE and Th, recovering F as fluoride, producing a leach residue amounting to 1/3 of an equivalent high temperature residue and containing <0.03% Th and radioactivity < 3×104 Bq/kg compared to the normal high temperature residue containing 0.2-0.3% Th and 1×105 Bq/kg. 2. Separating Th with N1923 and extracting RE by P507 has been completed in mixer-settlers. Test results indicate that the ThO2 product has a purity of > 95% with a yield of 99%, and the RE has a yield of >95%, in which ThO2/REO <5×10-6, and that P507 loaded RE connect straight with separating RE using P507-HCl system. 3. Treatment and multipurpose use of "three wastes" (water, gas and solids) are discussed in some detail."

Jan 1, 2014

By J. E. Udd

"In early 2000, CANMET-MMSL was engaged by the Ontario Ministry of Labour (OMOL) to conduct an international study of the practices, in several key mining jurisdictions, of determining the criteria that are used to decide when the wire ropes used in mine hoisting are to be retired from service. Subsequently, the author visited key officials and institutions in Canada, the United States, the Republic of South Africa, the United Kingdom, Germany, and Poland. Material from the Australian province of New South Wales and Hungary was also included.The report that resulted included, among other sections: (1) the history of wire ropes and trends in manufacturing technology; (2) a review of mine hoisting practices; (3) the requirements regarding safety factors; (4) a review of the various operations and their potential future development; (5) the criteria for rope replacement; (6) potential future developments that could take place in both hoisting and rope inspection practices in Canada; and (7) recommendations.Subsequently, the report was issued by OMOL, and as a CD-ROM by CANMETMMSL. In this paper the author presents the key findings and the recommendations made in the study."

Jan 1, 2004

By R. Degel

Keywords: Pyrometallurgy, DC furnaces, electric smelter, FeCr, FeNi, FeMn, Si metal, ferro-alloys, platinum production, circular furnace, energy recovery system In 1906, the first submerged-arc furnace was supplied by SMS Siemag. Since then, the division has become established in various industries such as ferro-alloys and non-ferrous metals, and in numerous other special applications. During the evolution of this technology, more efficient units with longer lifetimes were developed. Today, especially the potential of DC-based smelters, raises worldwide attention, with some projects having already started to implement this kind of technology. This paper evaluates SMS Siemag?s general viewpoint regarding the potential application of DC smelter technology and possible options for the ferro-alloy and non-ferrous industry. SMS Siemag is currently executing a FeCr project in Kazakhstan, where four of the world?s largest closed-type DC smelting furnaces, with a power input of 72 MW, will be installed. These furnaces include the latest technological features of modern DC smelters, which are described in this paper. SMS Siemag has started a long-term research and development project allowing a direct comparison of AC versus DC technology on a large scale, using a recently installed 1 MVA test furnace at the IME at the University of Aachen, in Germany. For open-type ferro-alloy and Si-metal furnaces, SMS Siemag has developed an energy recovery system, which is presented in this paper.

Jan 1, 2011

By R. Hardy

LaModel is a boundary-element program capable of calculating the displacements and stresses in thin bedded deposits such as coal, salt, or potash. Throughout its history, it has continually been upgraded in order to expand analysis detail and stay current with the latest advances in computer technology. The most recent enhancements include: an increased grid size capability, a significant increase in the speed of the automatic grid generation using an AutoCAD visual interface, implementation of subsidence-based horizontal strain calculations for multiple-seam situations, and pillar safety factor calculations. To demonstrate these new features, a multiple-seam case study of a longwall panel undermining an active set of main entries is presented.

Jan 1, 2006

By Dan A. Brown

The New Mississippi River Bridge (MRB) employed conventional design-bid-build procurement, but the bidding process included the opportunity for pre-qualified bidders to develop and propose confidential Alternative Technical Concepts (ATC?s) for evaluation and approval in advance of bidding. The ATC process provides a mechanism for value-engineering prior to bid, with incentives and opportunities for both the owner and the bidding contractor. The contract described in this paper is for the river bridge composed of a cable-stayed crossing with two pylons and the anchor piers on each side of the river. The Massman-Traylor-Alberici (MTA) team developed a re-designed foundation system for the main pylon and anchor foundations which utilizes their equipment and experience along with field load test measurements to optimize the foundations. The paper describes the experience with the use of the pre-bid ATC process on the project from the perspective of the bidder, and outlines some of the benefits and limitations of this concept with respect to foundation design and construction. Some keys for success are identified and impediments to the effective implementation of the process are described.

Jan 1, 2011

By Steven M. Rupprecht

"The artisanal mining sector in Central Africa is largely informal, yet provides an essential livelihood for many (directly or indirectly) participants, as well as facilitating an important source for the flow of income into many communities. Artisanal mining varies from site to site, but appear largely well structured despite its informality. The artisanal mining sites in Central Africa have some inherent management structure and the extraction itself is often organised. Artisanal mining is labour intensive and is generally conducted utilising hand digging methods e.g. shovels or hand chisels. Artisanal mining is generally more dangerous than small-scale or large-scale modern mining operations. This is especially true as artisanal operations are generally subsistence activities with artisanal miners focusing more on immediate concerns than the long-term consequences of their activities. When miners have no other source of income, they will usually find ways to evade controls and carry on working. The objective, through proper/dedicated training of artisanal miners is to migrate Artisanal mining to establish a small-scale mining (SSM) industry in Central Africa. Through developing the necessary skills in the fundamental areas of mining it is proposed that Artisanal Mining can become more productive and safer mining operations. The paper reviews the above focus areas, highlighting the skills and tools that are necessary to assist in establishing a sustainable small scale mining industry migrating from manual labour to semi-mechanised mining and processing. The purpose of the transformation process is to create a safe, healthy, environmental and community oriented mining operation with the objective to uplift the skills and wealth of the mineworkers and the general community."

Jan 1, 2015

By A. Pratt

Portland cement is primarily used to solidify backfill in underground mine workings and it represents a major cost in mining operations. CANMET-MMSL has invented an alternative binder technology that does not contain any amount of Portland cement and is made using waste materials, such as development rock and smelter slag. The technology has been successfully tested with many types of base metal and ferrous slag. Research conducted in collaboration with several mining operations in Canada has shown that the CANMET-MMSL binder has considerable potential as a replacement for Portland cement in mine backfill. An integral part of the overall mining operation, backfill is used for two main purposes: safety and environmental remediation. Depending on the mining method used, backfill provides a working surface, stabilizes stope and pillar walls, as well as the surrounding rock mass, and controls caving of stope backs. There are several benefits associated with the replacement of Portland cement in backfill, including reductions in (i) the footprint by placement of slag waste underground, (ii) the environmental effects and long term liability resulting from disposal and containment of slag waste on surface such as acid rock drainage, (iii) GHG as a result of reduced Portland cement usage (the production of 1 ton of Portland cement produces 1 ton of GHG), and (iv) the significant costs associated with reduced Portland cement usage.

May 1, 2010

By C. Lorimer Colburn

"The diverting of men from industry to combat in the world's war focused the attention of the operators in this country upon mechanical means of doing things. The demand for man-power -was so insistent that every available agency for multiplying it had to be employed. It was during the 1period of the war and immediately thereafter that development of the use of underground loading devices made most rapi4 progress. In all parts of the United States, mining engineers and mine managers were diligent in their efforts to develop mechanical loaders. The mining engineers of the U. S. Bureau of Mines in every section of the country have secured, with the cooperation of the mine operators, data on the actual performance of the mechanical shovels in their districts, and have made them available to the author of this paper.No effort has been made to discuss exhaustively the subject of underground loading devices. It has been the object to collect together in one paper, records of the performance of all machines now in actual use. Improvements in the design of machines are constantly being made the performance records given in this paper relate to operation prior to March 1 1 1921. The records prior to 1920 cay not fully represent the work that could be accomplished with the present models of the same machine.The data secured are given exactly as reported by the mine operators. Since this data were collected there have been two underground loaders, of a different design, put into operation in the iron mines of the Lake Superior District. One is the John Mayne Sub-level loader, being tried by the Cleveland-Cliffs Iron Co., Ishpeming, Mich., and the other is the Cole-Goudie shovel, being tried by the Oliver Mining Company, at Ironwood, Mich. No information has been secured regarding the performance of either of these machines."

Oct 1, 1921

By Taylor R. G

This paper reports a biogeochemical study of the Siberia lode of the Herberton tin field. Soil near the orebody contained high levels of Fe, Cu, Pb, Sn, As, Mld Mn. Polycarpaea spirostylis and Indigofera dominii were associated with these high levels but several other species apparently could not tolerate them. The potential of these species as indicator plants is discussed.

Jan 1, 1975

Results obtained from small scale tests using Australian tin concentrates indicate that metallic tin containing less than 0&#183;1 per cent iron can be recovered by a two-stage process using hydrogen and make-up chlorine. In the first stage the concentrate is ground,. pelletized, roasted, and reacted at 650&#176;C with HCI and H2 to volatilize the tin as SnOI2. The volatilization reaction is conducted with cocurrent gas and solids flow because it was found that the use of cocurrent flow yielded a solids residue substantially free from FeCI2. The second stage uses a technique termed &quot;reflux reduction&quot; during which the SnOl2 produced by volatilization is reduced by hydrogen to form tin and a gas containing HCI and H2 of sufficiently high HCI tenor for recycle to the volatilization stage. The elimination of tin ranged from 98+ to 99&#183;7+ per cent of the tin from concentrates containing 5 to 50 per cent tin, respectively. The process should be capable of continuous operation, and a tentative calculation has shown ,that a treatment rate of 12,000 tonnes of tin concentrate per year could be obtained in a volatilization reactor 1&#183;1 m in diameter and 6&#183;1 m high. The process may have particular application to finely divided concentrates containing less than 20 per cent tin.

Jan 1, 1974

Even though the economy of the United States remains in recession ? or not, depending on which economist you listen to ? muicipalities still need improved transportation, water and wastewater transit systems. And they are willing to spend the necessary funds on those systems, provided they are affordable, environ-mentally friendly and sustainable. From June 20-23, professionals in the tunneling and underground construction industry from around the world gathered in Portland, OR to learn new ways of providing those systems using the latest technology available. The North American Tunneling (NAT) conference attracted 803 attendees and 108 exhibiting suppliers of equipment and services.

Jan 1, 2010

By J. Daavittila, P. Jokinen, M. Honkaniemi

In the latter part of the 1980?s Outokumpu Chrome in Tornio, Finland, was in a situation when its twenty-year-old ferrochrome plant was becoming inefficient to sustain economically sound production. The company made extensive studies on the then available processing methods to find out the best possible processing route. As a result the whole plant was practically rebuilt and expanded. When equipment was proven in practical operation an application for FeMn production was developed. Now when Tornio FeCr-plant is considering the expansion the same type of exercise is to be performed with today?s challenges, which will be discussed in the paper. These challenges include increasing costs or decreasing quality of raw materials, increasing energy costs, stricter environmental regulations and demand of better working conditions. The possibilities to respond to these challenges will be discussed in the paper. The future and continuing development with FeCr includes the better utilization of process dusts and a lower consumption of energy. By adapting the latest automation tools to better control of the process even higher efficiencies can be achieved with present technology. New processes are considered for development in the future and some possible technologies will be described.

Jan 1, 2004

By LaTasha R. Swanson, Jennica L. Bellanca

Proximity detection systems (PDSs) for mobile machines have the potential to decrease injuries and fatalities. Early adopters of the technology have identified some challenges, which present an opportunity to explore and improve the integration of mobile PDSs in underground coal mines. The current research study applied the task-technology fit framework to investigate the fit between mobile PDS technology and mining relative to health and safety, from the perspective of leaders at two coal mines. Quantitative results from the study show that mine leaders evaluated mobile PDS favorably for training and ease of use, system feedback, user authorization and experience, and less favorably for safety, compatibility, task completion, and reliability. Qualitative results reveal specific task, mine, and system characteristics that may have influenced leaders’ evaluations. The study includes considerations and suggestions for safe technology integration

By LaTasha R. Swanson, Jennica L. Bellanca

Proximity detection systems (PDSs) for mobile machines have the potential to decrease injuries and fatalities. Early adopters of the technology have identified some challenges, which present an opportunity to explore and improve the integration of mobile PDSs in underground coal mines. The current research study applied the task-technology fit framework to investigate the fit between mobile PDS technology and mining relative to health and safety, from the perspective of leaders at two coal mines. Quantitative results from the study show that mine leaders evaluated mobile PDS favorably for training and ease of use, system feedback, user authorization and experience, and less favorably for safety, compatibility, task completion, and reliability. Qualitative results reveal specific task, mine, and system characteristics that may have influenced leaders’ evaluations. The study includes considerations and suggestions for safe technology integration

By C. J. Allen, L. Battiston

"Introduction It has long been recognized by the hot-dip galvanizing industry that the characteristics of the galvanized coating can be influenced significantly by steel and pro cessing variables. Probably the variable of most concern to galvan izers today is steel chemistry. More specifically, the problem is the excessive reactivity of continuously-cast, silicon-bearing steels. In the past, structural steels processed by general galvanizers were in the low-to-medium ca rbon category and contained silicon at either low impurity levels (as with rimmed steels), or less than approximately 0.10% (as with semi-killed steels). The structures of the coatings produced on such steels are characterized by dense, compact layers of delta and zeta iron-zinc alloy phases and a distinct outer layer of eta zinc, which usually imparts a bright shiny appearance to the coating. The presence of silicon in steel, above the so-called semi-killed levels, is known to cause marked stru ctural changes in galvanized coatings. Such coatings are characterized by a relatively thin delta layer, a thick , coarse zeta layer and frequently an absence of the eta layer. The eta phase, comprising zinc which is carried out of the bath during withdrawal of the work, can be consumed by the continuation of the coating reactions until its temperature drops to the solidification point. This results in a dull grey and often mottled surface instead of the usually bright metallic appearance. These galvanized coatings are usually much thicker than coating specifications requ ire and they are usually more brittle and have poor adhesion to the steel. In service, these coatings tend to develop a rust-like discolouration. With the wider use of continuous casting by the steel producers and the associated additions of silicon in this process, the problem is becoming more important and receiving greater attention from the galvanizing industry ."

Jan 1, 1987