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By J. J. Bezuidenhout

The waste-heat boiler is used within the Sulphide flash smelting process as the main dust and energy recovery unit. The large volume of off-gas discharged from the flash smelter is at a very high temperature (1350°C) and contains a significant dust load that subjects the downstream waste-heat boiler to tough and demanding conditions. The boiler cavity is especially prone to dust accretions, fouling, and corrosion caused by accumulation of molten particles and precipitation of sulphuric acid. Computational fluid dynamics (CFD) is applied within a qualitative study to model the flow and heat transfer distribution throughout the waste-heat boiler. The commercial CFD package, Fluent 6.2.16, was applied to a modified waste-heat boiler (23 m ×11 m ×5.4 m) within the Outokumpu flash smelting process. This investigation focuses on the geometric modifications to the typical boiler design, which includes elevation of the ceiling, placement of flow-obstructing baffles and radiation plates parallel within the flow path. Also investigated were various boiler operating conditions such as the circulation of process off-gas, air leakage from the dust discharging hoppers and variation in inlet gas composition. The geometric modifications had the desired effect of increasing the volumetric utilization and therefore enhancing heat transfer between the boiler surface and the gas stream and dust segregation. Introducing circulated off-gas at a rate of 20 m/s and at a 45° angle to the front of the waste boiler further enhanced cooling while reducing the high impact of the furnace-uptake gas-stream on the boiler ceiling. The placement of radiation plates was found to be very effective in enhancing the heat transfer surface and distributing gas flow within the boiler. These results present recommendations towards an improved waste-heat boiler design. Keywords: flash smelting, waste-heat boiler, CFD simulation, off-gas cooling.

Jan 1, 2008

By Clyde L. Holmberg, Paul Zinner

"INTRODUCTION In view of the large tonnage of low-grade iron ore and iron-bearing material known to exist at the western limits of the Gogebic range, the Bureau of Mines undertook an investigation of the area for the purpose of evaluating the iron-bearing formations as sources of iron for possible future utilization.After 6o years of exploration an, development on the Gogebic range, the area investigated by the Bureau represents the known western limit of direct-shipping ore mined from operations on the Gogebic range.An area about 2 miles in length between the villages of Pence and Iron Bolt in Iron County, Vic., was selected for investigation, and trenches wore excavated through the overburden and fully across the iron-bearing formation to obtain 108 bulk samples for beneficiation tests. Exhaustive tests involving gravity and flotation methods, magnetic separation, and magnetizing roasts followed by magnetic separation were conducted on the samples to determine the ammability of the individual formations and the entire iron-bearing zone to beneficiation.Empirical data on the character and mineral content of the formations arc tabulated herein, as well as the results of the beneficiation tests."

Dec 1, 1947

By J. A. McCamley

Gypsum scrap generated from wallboard manufacturing, construction and deconstruction activities in North America, Europe and Japan is a recognized environmental problem. Landfill disposal of this gypsum scrap is problematic, with deposits often creating hydrogen sulphide emissions and metallic sulphide groundwater leachates. Of these regions, Europe is the most advanced in dealing with the issue having enacted legislation, which will come into effect in July 2005 that will strongly encourage gypsum recycling throughout the EU. An estimated 10% to 17% of all gypsum used in the wallboard industry becomes recyclable scrap, which represents approximately 1% of the total waste stream in North America. In the United States, 2.5 to 4.5 Mt of gypsum scrap is generated each year; the volume is similar in Europe (the percentage of total tonnage is less because of the higher use of brick and concrete). The Greater Vancouver region of British Columbia has banned gypsum from its landfills, and as a result, all gypsum scrap is now recycled. New West Gypsum Recycling, a Canadian firm, uses its proprietary technology to process large quantities of gypsum scrap that is reincorporated into new wallboard, at percentages ranging up to 25%. The operation of New West Gypsum Recycling Inc. of Langley, Vancouver is examined as a case study and recommendations are provided as to how other urban regions can implement similar gypsum scrap recycling programs.

Jan 1, 2004

By B. Radwanek-Bak

The assurance of future raw materials supply to the EU mineral industry has become, in recent years, one of the most important tasks of the EU Commission. It is focused on creation a new mineral policy within the EU zone. One of the starting points for this activity was identification of the mineral commodities that are critical for the sustainable development and technological progress. The paper presents the glance to this problem from the National Member level. Domestic mineral reserve base as a possible source of critical raw materials for the EU was shown. Poland cannot be considered as its resource base. The source of these raw materials are not only scarce in Poland, but also they are not produced, and their demand is now - and according to forecasts is going to be in the future - met by imports. The raw materials in question are not considered exactly critical for Polish economy, but they are of limited economic importance. On the other hand, their growth is a best opportunity and at once the need to the future sustainable development.

Jan 1, 2011

By M. Alley, P. Schroeder, L. Zelazny, S. Nagle

The Old Hickory mineral sands ore body in Virginia (>2000 ha) currently supports a productive rowcrop agriculture. Reclamation experiments were implemented on pilot-scale mining pits from 1995 to 1998. Half of each mining pit was topsoiled (25 cm) while the remaining half was left as either (1) mixed tails/slimes or (2) re-graded subsoil over tails/slimes treated with 112 Mg/ha yardwaste compost. Post-mining productivity was estimated to be reduced by 23%, 3%, 27%, and 20% for each crop (wheat/soybeans/corn/ cotton) in sequence when compared to undisturbed soils. Variability in surface texture and compaction limit restoration of soil productivity.

Jan 1, 2002

On the Kinetics and Equilibrium Models for Biosorption of Ni(II) onto a Gram-Positive Bacteria Strain, Rhodococcus opacus, for Environmental Applications The aim of this fundamental study was to evaluate the biosorption of Ni(II) from aqueous solution streams onto a Rhodococcus opacus strain through kinetics and equilibrium isotherms studies. The biosorption of nickel achieved its highest value in a pH around 5. The experimental data evaluation was carried out focusing three two-parameter models, as: Langmuir, Freundlich, Dubinin - Radushkevich. In order to determine the best isotherm fit, three error analysis methods were used to assess the data: correlation coefficient (R2), residual root mean square error (RMSE) and Chi-square test. The error analysis established that the Freundlich model fits better the nickel biosorption data. Maximum uptake capacity of nickel reached a value around 7.63 mg.g-1 for R. opacus. The biosorption rate was fast and achieved a removal of around 79 per cent of Ni(II) in the first 5 minutes at room temperature (25 ¦ 2¦C). The experimental kinetics data was evaluated considering two models (pseudo-second order and pseudo-first order). The error analysis established that the pseudo-second order model better fits the data.

Sep 13, 2010

By M. Pekguleryuz, S. A. Argyropoulos

"The recovery of additions in light metals is an important parameter influencing consistency of the finished product, which ultimately means cost. Recovery is a function of many parameters such as assimilation speed, addition density, addition practice, liquid metal processing conditions, etc. In liquid metal processing operations, it is desirable to have the maximum possible recovery at the shortest possible time.In this paper a new index will be presented, namely, the rate of recovery (RR). This index quantifies the addition recovery and introduces the time dimension in the recovery increase. As such, the RR equips the liquid metal practitioner with an accurate picture of addition assimilation in liquid metals. Results will be presented on how this index is applied to a variety of additions in liquid aluminum. IntroductionThe data on addition assimilation kinetics offer a valuable parameter describing how fast a given addition enters the metal bath. These data may be expressed as gr m-2 s-1 of additive for a set of experimental conditions which might include bath temperature and degree of bath agitation among others. However, the liquid metal processing practitioner is more interested in the recovery of additions. In other words, the point of interest is the percentage of the used addition entering the metal bath. Ideally, the addition recovery can reach the 100% level. However, in practice, the addition recovery never or rarely reaches that level. Many factors can contribute to this. Some of these factors can be slow assimilation kinetics, addition density, addition practice, turbulence of the melt, etc. In some cases, sloppy addition practices can contribute to low recoveries, or even worse, to erratic recoveries.In this paper a new parameter is introduced. This parameter relates the maximum addition recovery observed over the time needed to achieve this maximum recovery."

Jan 1, 2002

By D A. Manhire, R M. Flores

The commercial develop of coalbed methane from the Powder River Basin has demonstrated that low-rank coals can be a viable source of gas. Currently over 20 000 coalbed methane wells exist in the Powder River and it is predicted that there will be 50 000 wells by 2010. What makes the Powder River Basin successful is the thickness of the coal (in excess of 30m) as well as the low ash content (

Jan 1, 2002

By Tim O’Neil

What prompted the merger of the two long-established American Mining Congress/National Coal Association (AMC/NCA) groups that combine the coal, hard-rock, industrial- and agricultural-minerals sectors of mining? Both associations have been facing similar stresses for several years - structural changes in their respective industries, the changing personality and role of government and well-financed and organized opposition groups. In 1993, the AMC board of directors undertook efforts at reorganizing the association. One board member, who serves on both boards, suggested it might be time to give serious consideration to merging the organizations. This is an idea that had been discussed more or less informally at least three times during my tenure at NCA. Negotiations toward a merger began after that and were consummated in February of this year.

Jan 1, 1995

By C. Chongo, F. X. Paquot, C. Ngulube

"Over the last six years, the Kansanshi copper/gold mine has continued to process significant quantities of complex transitional mixed ores. The effect of the complex mineralogy on the flotation performance is depicted. Initially, ore treated came predominantly from accumulated stockpiles. In the ensuing years, ore treated shifted to primarily freshly mined ore that generally showed less tarnish with better float kinetics but with the downside of producing lower concentrate grades. A number of changes were made to improve the efficiency of the roughing circuit and quality of concentrate produced. These changes were as a result of initial mineralogical studies and laboratory float test work done and discussed at length in a previous paper. Salient among the adopted recommendations from previous work were increasing circuit capacity and modifying configuration to increase the residence time and the number of sulphidisation stages. These modifications were completed and commissioned in 2011. This, however, resulted in significantly low rougher concentrate grades and subsequently below-specification final concentrate product. This was primarily due to higher mass pulls resulting from the extended rougher bank with multiple concentrate discharge streams. This necessitated the need for an enlarged cleaning capability to offset this. The extra cleaning capacity came on-stream in 2014. Of note was the development of a recovery model, based on the strong correlation between the total copper and acid-soluble copper ratio, as a tool for monitoring plant performance. INTRODUCTION The Kansanshi mine, the largest copper mine in Africa, is 80% owned by Kansanshi Mining PLC, a First Quantum subsidiary. The remaining 20% is owned by the state through the parastatal ZCCM. The mine is located approximately 10 km north of the town of Solwezi and 180 km to the northwest of the Copperbelt town of Chingola. The mine has been in commercial operation since 2005. Prior to June 2009, Kansanshi mine treated only two ore types: oxide and sulphide. All transitional ores mined during the period leading up to 2009 were stockpiled. The treatment of the minerologically complex, transitional ores through a third train commenced in June 2009 but with numerous metallurgical challenges. This transitional ore (called mixed ores) could not be previously treated economically due to high gangue acid consumption (GAC) minerals association (making it unsuitable for the oxide float–leach circuit) and poor flotation response ruling out the conventional sulphide float circuit. The new novel circuit involved a conventional sulphide pre-float followed by flotation involving staged controlled potential sulphidisation (CPS)."

Jan 1, 2015

Every two years, industry leaders and practitioners of tunneling and underground construction gather at the Rapid Excavation and Tunneling Conference (RETC) to learn from their peers about the most recent advances and breakthroughs in this unique fleld. Industry experts from around the world highlight their most recent projects and share real-world experiences. They also share with their colleagues new technologies and methodologies that attendees can take home to their respective projects. The 2013 RETC was held June 23-26 in Washing-ton, D.C., itself home to several major tunneling and underground construction projects. The conference is sponsored by SME. Attendance was 1,384 professionals. The accompanying exhibit hosted 159 companies in 188 booths. A few of the topics covered in the technical sessions dealt with caverns and large spans, contracting practices, tunnel linings, design and planning, geotechnical considerations and instrumentation. The conference was preceded by four short courses, all well attended. They were ?Grouting in Underground Construction,? ?Tunnel Lining Design,? ?Microtunneling Application? and ?Risk, Uncertainty and Hard Decisions.? In addition, a sold-out field trip to D.C. Water?s Blue Plains Tunnel took place following the conference. The Blue Plains Tunnel is part of the agency?s Clean Rivers Project. Also during the meeting, three students each received $5,000 scholarships from the UCA of SME, while another three students each received $2,500 scholarships from RETC (See page 53).

Sep 1, 2013

By A. D. Thomas

Some years ago, the authors developed an analysis of non-Newtonian pipe flow based on enhanced turbulent microscale and associated sublayer thickening. This analysis, which can be used for various rheologic modelling equations, has in the past been applied to smooth-walled pipes. The present paper extends the analysis to rough walls, using the popular Bingham plastic equation as a representative rheological behaviour in order to prepare friction-factor plots for comparison with measured results. The conditions for laminar-turbulent transition for both smooth and rough walls are also considered, and comparisons are made with earlier correlations and with experimental data.

Jan 1, 2007

Viscosity measurements were carried out on slags in the CaO-Cu2O-CuO-MgO-SiO2systemcontaining ~ 63 wt% SiO2in air. The experimental work was carried out over a range of temperatures where the slags were completely liquid. Initial measurements were on a binary CaO-SiO2slag to which incremental additions of CuxO-MgO-SiO2slag with the same silica mole fraction were made. The viscosity-temperature relationship was measured for slags with‘Cu2O’contents of 0.02, 0.19, 0.38, 0.79, 1.69, 2.47, 3.01, 5.31 and 10.0 wt%. The proportions of Cu+and Cu2+in the slags were determined. The oxidation state of Cushifted from predominantly Cu+to Cu2+, with the Cu+/Cu2+ratio of approximately 0.3 for slag with a Cu content above 2 wt%. This is equivalent to Cu1.13O. The trends observed for changes of Cu2+/Cu+redox ratio with slag chemistry were consistent with the literature. Decreasing the CaO content by substituting copper oxide resulted in a decrease in the Cu+/Cu2+redox ratio. The change in ratio corresponded to a shift of the value of x in CuxO from an initial value of 1.8 to 1.1,when the slags contained 10% ‘Cu2O’. In this study, the SiO2content of the slags varied between 64 and 60 wt% as the Cu content increased. The viscosity of the slag containing 10 wt% CuxO was nearly 4.5 times lower than the binary CaO-SiO2slag. As the silica mole fraction (xSiO2) actually stayed constant (0.61±0.009),the results show that CuxO acted as a network breaker. Comparison with other ternary slags with similar silica mole fractions suggest that that addition of CuxO to silicate slags has a stronger effect on lowering the viscosity than FeO or MnO has on a molar basis. Keywords: viscosity, copper, silicate, slags

Jan 1, 2004

By Alberto Pacheco Pacheco

En el presente texto se analiza el fundamento de lógica fuzzy aplicada al control de molienda de minerales, la que nos permite simular el comportamiento humano en la operación molienda, con la que se plantea el algoritmo de control inteligente de molienda.

Sep 12, 2005

By J. L. Thompson

The U.S. Bureau of Mines conducted a water-jet-studies program using a single-bit, in-seam test unit to determine effects of a moderately high-pressure (up to 10,000 psi) water-jet-assisted cutting system on rock weakening. The in-seam test unit was used to obtain cutting force data in tangential, normal, and side force directions. Conical continuous miner and radial longwall miner bits were used to penetrate test samples of coalcrete, Berea sandstone, and Indiana limestone with unconfined compressive strengths of 4,600, 8,000 and 10,000 psi, respectively. Depth of cut in the coalcrete tests was 1 in, with 2-in cut spacing (2:1 ratio). Because of cutting equipment and instrumentation limitations, the Berea sandstone and Indiana lime-stone were cut using a 0.5-in depth of cut and 2-in spacing (4;1 ratio). Bit velocity was maintained at 25 ft/min for both bits. Each specimen and bit type was tested using 0.3-, 0.6-, 0.8-, and 1.0-mm-diam nozzles and water-jet pressures of 2,500, 5,000, 7,500, and 10,000 psig. Water-jet-assisted cutting decreased average resultant conical and radiallongwall bit cutting forces 6.4 and 8.4 pct in coalcrete, 5.5 and 1.4 pct in Berea sandstone, and 2.0 and 5.5 pct in Indiana limestone. Slight reductions of power requirements resulting from water-jet assist were ascertained during these experiments.

Jan 1, 1989

By Jan L. Reichelderfer, Thomas L. Richardson

Completion of the H-3 Highway Tunnel Project was a critical element in opening this award winning project. The exploratory tunnel was completed as a maintenance tunnel and included difficult shafts extending into the main tunnel cross passages. The project also involved a major addition to the traffic operations center including a deep excavation in close proximity to the tunnel portal structures. The projects also included various completions and improvements to the main tunnels, such as paving, drainage, maintenance, and a variety of critical life-safety issues, such as radio systems, telephones, etc. The highway opened in December 1997.

Jan 1, 2001

By P. Brad Marchant

"To properly evaluate bioleaching as a commercial alternative for sulphide concentrate oxidation, to enhance cyanidation response, it was necessary to define and optimize critical operating variables outside of the laboratory under less than ideal conditions. A complete bioleach testing laboratory was installed at Equity Silver Mines to aid in pilot plant flowsheet development.A continuous pilot scale bioleach circuit was constructed to provide data for meaningful valuation of biotechnology on a plant scale. The important operating and design parameters for pilot plant testing are described. Plant scale feasibility and design considerations, to treat a refractory pyrite/arsenopyrite concentrate produced from flotation tailing, are discussed. 1.0 BACKGROUNDEquity Silver Mines Limited is located 37 km southeast of Houston in central British Columbia. A 70% owned subsidiary of Placer Development Limited, Equity is Canada's largest open pit silver producer. Ore reserves were estimated at 28 million tonnes grading 106 g Ag/t, 0.96 g Au/t, and 0.38% Cu from two pits, the Southern Tail and the Main Zone. Detailed geology and mineralogy has been described previously(1,2).The concentrator flowsheet consists of conventional crushing, grinding, flotation, and dewatering circuits processing 5 300 tonnes per day of new mill feed. The resultant Cu/Ag/Au concentrate is trucked to Prince Rupert for shipment to market. Mill tailing reports to a closed circuit pond from which mill process water is recycled. Details of the concentrator process have been reported( 2,3).Production in the Southern Tail pit, from July 1980 to March 1984, resulted in mill tailing averaging 0.9 g Au/t and slightly more than 20 g Ag/t. Historic data indicate that unrecovered gold is associated with arsenopyrite and silver losses with unliberated tetrahedrite or minor silve,, bearing sulphosalts. Main Zone mill tailing, which commenced production in March 1984, contains approximately 0.5 g Au/t which is probably associated by majority with silver bearing minerals and pyrite while silver losses, 30-40 g Ag/t, are associated with unliberated silver and antimony bearing minerals."

Jan 1, 1985

?Longhole blast hole drilling? techniques are not new to the mining industry. Appropriate mechanization and improvement of the techniques and application has evolved from the industry requirements. Today safety and economics play a larger role in the excavation of ore passes, ventilation passes, and relatively small inclined excavations in the conventional gold and platinum industry. The application of dropraise drilling from the top or from the bottom is discussed investigating the current techniques available, DTH application, advantages and disadvantages, limiting factors, typical layouts and proposals, the drop raising technique and future applications. Similarly, the application of longhole blast hole drilling in tabular and massive orebodies is discussed with emphasis on the DTH application, advantages and disadvantages, limiting factors, typical layouts, the long hole stoping techniques and future applications.

Jan 1, 2003

In This Chapter [Finding the dust source Ventilation and dust collector malfunctions Upgrading the dust controls Design stage ventilation planning ] This chapter explains how to reduce respirable dust76 in hard-rock tunnels during excavation by using tunnel boring machines (TBMs). The first steps in combating a dust problem are to take dust samples to pinpoint the source, check the ventilation system, and check the dust collector. If the ventilation system and dust collector are operating properly, then other dust controls such as water sprays and conveyor belt scrapers must be upgraded. For tunnels in the design stage, recommended air quantities are provided. FINDING THE DUST SOURCE AND LOOKING FOR VENTILATION MALFUNCTIONS [The first steps in fighting a dust problem are to take dust samples to pinpoint the source, check the ventilation system, and check the dust collector. Without knowing the exact source, efforts to reduce dust are hit-and-miss (mostly miss).] Taking samples to pinpoint the dust source. In tunnels with high levels of airborne dust, the first task is to pinpoint where the dust enters the airstream. Most dust originates from rock breakage at the tunnel face, but the location where this dust enters the airstream can vary. Dust can leak from behind the TBM face shield, from gaps in the ventilation duct, or from a mal-functioning dust collector. It can be entrained into the air from the muck on a moving conveyor belt. It can even be shaken loose from the underside of the belt as it passes over the idlers. As a start, to locate the dust source, dust samples and air quantity measurements should be taken at the following locations:

Jan 6, 2003

By J. O. Marsden

Parts I and II in this series of papers presented the chemistry of medium-temperature pressure leaching of copper sulfide concentrates and reviewed the metallurgical development of a process to effectively recover copper using medium-temperature pressure leaching and direct electrowinning (DEW). Part III reviewed the large-scale demonstration of the MT-DEW-SX process at Bagdad, Arizona. Key features of the process were the use of superfine grinding of the concentrate (to a P98 of 12 to 15 µm and a P80 of 6 to 7 µm), pressure leaching at 160ºC with 1,380 kPa (200 psig) oxygen overpressure, DEW to produce LME Grade A cathode, recycling some of the lean electrolyte to the pressure leaching step, and treatment of a lean electrolyte bleed by solution extraction (SX). Recycling of lean electrolyte provided all of the acid required to effectively dissolve copper and convert approximately 65% to 70% of the sulfide sulfur to elemental sulfur, resulting in an acid-autogenous process for pressure leaching. This paper (Part IV) discusses the development and design of a full-scale commercial application for the Morenci operation in Arizona.

Jan 1, 2007