Search Documents

By R. F. Neider, W. R. Bain

"Expanding upon one aspect of a recent paper on ""Fluid Column Roasting at Sherbrooke Metallurgical Co. Ltd.,"" the present paper deals with the operation of the fluid column process to achieve substantial elimination of cadmium and lead during the roasting of pelletized zinc concentrates. Designed to meet the need for additional feed for Matthiessen and Regeler Zinc Company's vertical retort zinc smelter in West Virginia, without recourse to a sintering operation, the plant is capable of simultaneously attaining very low lead and cadmium levels on demand, through operation in the manner described. Fluidizing air admitted via the wind box is supplemented by natural gas admitted via a tuyere bank 15 ins. above the hearth, in quantities adjusted to maintain a reducing atmosphere within the interstices of the bed. In addition, careful attention is paid to bed temperatures, which run from 1,080° to 1,100°C. Under these reducing conditions, 90 per cent of the cadmium and 92 per cent of the lead in the feed are eliminated, the sulphate sulphur content is decreased by 0.5 per cent, sulphide sulphur is held at 0.6 to 0.08 per cent, and the zinc content correspondingly in-creases. The fuel value of the natural gas is recovered as extra steam, which carries a credit. There are some added difficulties with fume accretions, gas conditioning and gas -cleaning, some of which have yet to be overcome."

Jan 1, 1967

By T. S. Li, D. Ilievski, I. Livk

Micromixing of the fluid and the particulate phases in a continuous gibbsite precipitator was investigated for three different micromixing states, namely maximum mixedness (MM), complete segregation (CS), and maximum mixedness of the fluid but complete segregation of the particulates (MMF-CSP). The influence of the micromixing on continuous precipitation of gibbsite was studied at different precipitation conditions via simulation. Three different cases were considered with respect to the precipitation kinetics: (1) gibbsite secondary nucleation is favoured with slow crystal growth and agglomeration rates; (2) gibbsite crystal agglomeration and growth are dominant mechanisms with secondary nucleation suppressed; and (3) gibbsite crystal growth is the only relevant phenomenon. Simulation results for the cases (1) and (3) showed that the crystalline products for both the MM and MMF-CSP micromixing states were very similar, but the product obtained from the CS micromixing state was considerably different. This indicates that at those precipitation conditions the fluid micomixing has the dominant effect on the product properties, and the particulates micromixing effect is insignificant. However, when operated under the conditions of fast crystal growth and agglomeration kinetics, i.e. case (2), both the fluid and the particulates micromixing were found to affect the precipitation process, resulting in a significantly different product. Computational Analysis in Hydrometallurgy 35th Annual Hydrometallurgy Meeting held in conjunction with the 44th Annual Conference of Metallurgists ofCIM Calgary, Alberta, Canada Edited by

Jan 1, 2005

By M. Kucharski

The model of the Outokumpu direct-to-copper process deals with a steady-state process the parameters of which do not depend on time. To give a prediction for the process outcome, "a modified black box" method, which ignores most of the chemical reactions in the furnace, was used. This method takes input and output parameters into consideration. The presented model describes the Outokumpu direct-to blister process in the form of the set of linear equations which give mass and enthalpy balances as well as the distribution of elements between blister copper and slag. However, only major substances where quantities in the feed charge exceed a certain level (for example 0.5 kg/ lMg of smelted concentrate) are taken into consideration. Minor elements are distributed among slag and metal phases in a different way. Some of the equations are derived from distribution coefficients. The value of distribution coefficients can be calculated from plant production data.

Jan 1, 2007

By G. F. Trainor

The complex ore body at CNRL?s Horizon mine presents some unique challenges in managing ore and waste delivery. With 25m x 25m ore blocks shovels often take bucket loads from multiple blocks to fill one truck load. With CNRL monitoring 22 different qualities per material a precise calculation of the blended quality of ore on the back of each individual truck is essential to meet the daily blend requirements at the plant. Additionally, one of these qualities must be closely monitored and controlled at a singular level as delivery of certain grade and quantities can cause serious disruptions at the plant. The waste material also requires special handling and delivery for its use in dyke construction for tailings impoundment. Shale materials used in the construction contain high levels of saline that must be contained to prevent seepage into ground water. This paper will discuss how the use of Wenco?s survey-grade GNSS system on shovels, its dispatching algorithm, and fleet management applications give CNRL the ability and confidence to control and report on these three issues.

May 1, 2013

By G. Whittle, R. Peevers, P. Moryoussef

Enterprise optimization is a relatively new optimization approach to mine planning used to jointly consider all aspects of a mining operation affecting the mine planning process and related valuation. In this paper, it is applied at SEMAFO's Mana operations in Burkina Faso, consisting of several open pits and a proposed underground mine. The surface-minable ore is relatively shallow, and the pits are long and linear. The underground operations, as currently envisioned, will consist of a stoping operation accessed by two ramps from the surface. Power is a concern at this property due to local power being produced largely by diesel generators, and it has become one of the key optimization constraints. Other important parameters are the mining and processing rates, underground configuration and cutover elevation. Enterprise optimization was found to improve net present value for the Mana Operations property by simultaneously optimizing multiple parameters and constraints to arrive at an optimal pit and mining phase design, optimal cut-off grades over time, and optimal ore feed based on ore hardness, power constraints, and head wades. Reserves were expanded several times over the course of the study to improve the valuation of the mining operation and put SEMAFO in its present enviable position of ongoing reserve increases.

Jan 1, 2011

By Xiaoguang Zhao

The coal mining area in Northern Shaanxi, China, has been taken as the study area, and the damage mechanism of the ecological environment is discussed on the basis of analyzing the characteristics of natural eco-environment and resource development in this area. Mining subsidence is taken as an example, and by using the Gray Correlation Analysis method, the key impact factors have been selected. An assessment model with fuzzy comprehensive evaluation has been constructed, and 12 coal mines have been quantitatively assessed. This paper also constructs an ecosystem health assessment method and index system in the coal mine area on the basis of ecosystem health theory, and assesses the ecosystem health status in the Shenfu coal mining area from 2000?2006. The research results are expected to help the eco-environment protection process in the designated coal mining area.

Aug 1, 2013

By Jan Butra

Longstanding mining of copper deposits in the Legnica-Glogow Mining Basin, Poland has accumulated broad experience concerning the impact of geological and mining conditions on seismic and rockburst hazard. Methods of rockburst prevention for deep copper mines have been developed based on gathered data. Methods of rockburst hazard evaluation and rockburst control constitute a set of rockburst prevention measures. Due to their nature and location within the production process, prevention methods can be passive or active. Active methods of rockburst prevention consist of the liquidation of stresses in the areas where they are concentrated through controlled generation of rock-mass tremors and rockburst by blasting works (group extraction blasting, release blasting in the rock mass and pillars able to accumulate the stress, as well as in the roof and floor). Group blasting works as a basic method are very effective in copper mine conditions. Provocation of dynamic events makes it possible to control the timing of their occurrence. In Polish copper mines, all blasting works are made during the absence of miners in the mining fields. Daily distribution of both the number of recorded strong seismic events and volume of energy released, confirm the advisability of using this kind of rockburst hazard prevention. The rockburst hazard prevention methods developed over 40 years of copper deposit extraction are economically reasonable and offer sufficient effectiveness under high rockburst hazard conditions.

Aug 1, 2013

By L. Magne, A. Pinto, M. Maldonado, J. A. Finch

Estimation of gas holdup from electrical conductivity measurements has been used in lab and industrial installations. The approach is based on the application of Maxwell's model, which relates the concentration of a dispersed phase in a continuous medium to measurements of the electrical conductivity of the dispersed phase, continuous medium and the resulting mixture (dispersion). When applied to inferring the collection zone gas holdup in a three phase system and to facilitate real-time on-line measurement, the slurry is assumed to behave as the continuous medium and gas bubbles as a nonconducting dispersed phase. This article derives an equation for estimating gas holdup in a three phase system, eliminating the assumption that the slurry behaves as a continuous medium but rather as a dispersion of non-conducting solid particles in water. In this formulation only water behaves as the continuous medium in the sense of Maxwell, and gas holdup in a three phase system is then calculated from the application of the Maxwell model twice: (1) to determine solid content in a two-phase system, and (2) to determine solid plus gas holdup in a three phase system. To validate the new equation and quantify the errors incurred by assuming slurry is the continuous phase a laboratory flotation cell was instrumented to continuously measure the conductivity of two and three phase dispersions with known solids contents. As the amount of gas in a lab flotation machine is difficult to measure directly or by another indirect technique such as using pressure signals, 2.5 mm dielectric plastic spheres having a density of ca. 1.3 g/cm3 were used instead of air bubbles for validation. Experimental results demonstrated that the continuous medium assumption underestimates gas holdup and that the resulting bias error increases linearly with the solid content and decreases with the magnitude of gas holdup.

Jan 1, 2016

By C. Guo, R. J. Chalaturnyk, M. MacKinnon, J. D. Scott

The Mildred Lake Settling Basin (MLSB) is the largest disposal site for mature fine tailings (MFT) at the Syncrude Canada Ltd. oil sands plant. Over the past years (since 1996), there has been a marked change in the densification behaviour of MFT in the MLSB. Methane-producing microorganisms, known as methanogens, have become very active, and large amounts of biogas (mainly methane) have been produced. Continued field monitoring of the MLSB has provided convincing evidence of the rapid densification process (rapid water drainage from the tailings) at the area with intense microbial activity. This rapid densification has caused pumping challenges in the transfer of fine tailings from the Mildred Lake Settling Basin for the creation of composite tailings. It may also have potential positive effects in accelerating the reclamation of the oil sands fine tailings. A field and laboratory research program was carried out to study the mechanism leading to the rapid densification phenomenon. A review and discussion of the research program is given and some results from the field investigations and small-scale column tests are presented in this paper.

Jan 1, 2007

By P. H. Rodriguez

The aquatic hazard classification system of the OECD and EU requires that sparingly soluble metal substances (SSMS) be tested using the OECD Dissolution/Transformation protocol in order to quantify the release of the ecotoxicological relevant species (dissolved ions). The SSMS category contains massive forms of metals, which due to their low solubility and slow transformation characteristics are a special case. The main factors that produce the release of metal into solution are exposed surface loading, pH, and stirring rate. The classification system at present prefers the use of mass loading as opposed to surface loading, in which case the amount of metal released will primarily be a function of the pH, and mass loading. Within the framework of the European Copper Voluntary Risk Assessment, coordinated by the European Copper Institute, we have proposed and developed a methodological procedure in which we demonstrate that surface area is an intrinsic property of a SSMS and we link the exposed surface loading to the toxicity reference value in order to obtain an aquatic hazard classification for massive metals. As example, the aquatic hazard classification for copper massive will be discussed. This approach is recommended for metal massives and metal powders.

Jan 1, 2007

By Muhammad Zaka Emad

Cemented rockfill (CRF) is a mixture of rock aggregate and binder slurry. It is a stiff backfill, it is fast curing, its operation is simple, placement rate is reasonably high and no drainage is required. The main demerit of CRF is failure of exposed faces causing ore dilution, which can be associated with the fill placement method. This paper discusses the effects of two placement methods being practiced by mines and numerical modelling is used as a tool to evaluate stability of the backfill column. In the first method, practiced in longitudinal retreat mining of a narrow vein deposit, the rockfill is hauled and dumped into the stope with a LHD scooptram. Once dumped, cement slurry is sprayed into the stope. In the second method, a raise situated centrally above the mined stope is used to convey already mixed CRF into the stope. Stopes are mined out transversely in primary and secondary blocks in a sublevel stoping system. Problems of poor mixing in combination with both placement methods are discussed. The two backfill placement methods are analyzed for blast induced vibration damage using the dynamic Flac3D modelling technique accounting for rock mass and fill damping characteristics, and a pressure wave is used to simulate the blast vibrations. Fill heterogeneity has also been considered for the two cases and results are compared.

Jun 1, 2012

By H. R. Huffman

"This paper reviews the history of iron powder production, and outlines the varions production methods. The uses of iron powder and the reasons for its use are also covered. The paper concludes with a look at future trends in powder metallurgy.INTRODUCTION TO POWDERSTHE IRON POWDER INDUSTRY is enjoying a very rapid growth. The annual consumption of iron powder is now at the 100,000-ton level, twenty times higher than it was at the end of World War II, and the yearly in-crease bas been almost consistent at 20 per cent. This is expected to increase, bringing the tonnage to 200,-000, or even (according to some experts) to 270,000, in 1970. In any event, powder metallurgy is expanding at high speed and making an important impact on the production of iron and steel products. Some indication of the faith in the future market may be indicated by the commencement of three new powder production plants in Canada with a total capacity of 136,000 tons annually."

Jan 1, 1969

By E. P. Wiechrnann, C. M. Castro, G. A. Vidal

In copper Eta plants the optimal current density setpoint depends on the electrolyte composition and temperature. However, conventional plants operate with large standard deviations. A value of 14% with current densities offsets up to ±50% is typical. For worst, during opencircuit or shortcircuit events this variation can be from -100% to +200%. Naturally, energy consumption and copper quality are compromised. Several devices have been successfully employed to reduce set point deviations. Last developments include; Optibar Segmented Intercell Bars, Outotec Electrodes Arranging Method and NTC Selective Electrodeposition Enhancers. This paper researches and compares these technologies. It is shown that short circuits can be effectively reduced in occurrence and magnitude. Moreover, 95% of the electrodes can be forced to operate within ±10% of the set point. The specific energy consumption is reduced from 2,000 KW per Ton to values close to 1,900 KW per Ton.

Jan 1, 2011

By X. -G. Chen, J. Qin, K. Liu, D. Racine

"Understanding the thermo-mechanical fatigue (TMF) behavior of materials plays a significant role in the safety design of critical components used in aerospace and automotive industries, such as engine blocks and cylinder heads, which undergo the cyclic change of temperature and stress. However, the cyclic changes of temperature, stress and strain make it difficult using the traditional testing methods to accurately simulate the TMF process. In the present work, the Gleeble® 3800 system was successfully applied to develop a reliable procedure to measure the TMF behavior of aluminum alloys. The modified setup together with the new designed program allows the Gleeble system to precisely simulate the cyclic profiles of temperature and mechanical strain. The novel procedure includes the calibration and verification of the TMF setup to ensure the test validity with Young’s modulus measurement, multi-cycle measurement of the thermal strain and zero stress adjustment followed by online monitoring the TMF cycles. The results of the TMF testing of an AA6061 alloy under cyclic temperatures (60–300°C) and various strain amplitudes (0.2–0.6%) were demonstrated. Its TMF behavior was characterized by the typical hysteresis loops and cyclic stress-strain response.INTRODUCTION The thermo-mechanical fatigue (TMF) behaviour becomes increasing important to evaluate the elevated-temperature properties of materials used as the critical components in automotive and aerospace industries, such as the gas turbines (Hu, Shi & Yang, 2016; Moverare, 2007; Segersäll et al., 2015) and engine blocks (Grieb, Christ & Plege, 2010; Javidani & Larouche, 2014). During the cycles of start-up and shutdown of the engines, these components undergo a complex change of loading. Meanwhile, a dramatic temperature gradient exists on the components due to the cooling system. Therefore, the cyclic changes of load and temperature can give rise to the TMF and may limit the use life of such components (Hu, Shi & Yang, 2016; Javidani & Larouche, 2014; Moverare, 2007). Hence, performing the TMF tests to precisely simulate the cyclic changes of load and temperature to understand the TMF behaviours of materials is playing a significant role in the safety design of these components. For TMF tests, two principal types of cycles are generally employed, including the in-phase (IP) cycle where the load and temperature are at the same phase (i.e. maximum load at highest temperature) and out-of-phase (OP) cycle where the maximum load is applied at minimum temperature (Kliemt, 2012; Miller, 2014). The most significant damage mechanisms in engine components are reported to be OP TMF cycles (Javidani & Larouche, 2014; Kliemt, 2012)."

Jan 1, 2018

By K. Sakai, M. Miyaue, T. Aoki, T. Tani, S. Tanaka, N. Kudo

In the planning stage of a tunnel, due to limited available technology in the geological survey and the financial restriction, tunnel supports are often designed from unsatisfactory information, and the tunnel construction is started. Therefore, "observational construction" is carried out in the construction stage, in which the design is rationally verified and modified by observations/measurements. Moreover, the ground conditions ahead of a tunnel face must be predicted for efficient and safe tunnel construction. The authors have examined effective prediction methods to the ground conditions ahead of a tunnel face under construction of a mountain tunnel (Aoki et al., 2010) in view of the established method (Schubert et al., 1995). Though the prediction method of Schubert et al. requires the displacement in the direction of tunnel axis, it is difficult to obtain its accurate data by the electro-optical distance meter. Then, we have proposed a method that uses tilt sensors installed at the tunnel crown near the face to obtain the slight tilting information. To measure inclination of the tunnel crown, this inclinometer was originally developed as a daily management measurement, such that the geological condition and its possible change behind the face could be detected early, and a steady advance and construction safety could be ensured. This paper describes the method of forward prediction mechanism and advantages of this proposed method. It then presents the typical results of a field demonstration test at a tunnel under construction. Lastly, the predictable range from the stratum boundary at which ground stiffness changes are discussed based on the results of three-dimensional numerical analysis.

Jan 1, 2015

By C. W. K

This little sketch of the late Willet G. Miller, Provincial Geologist of Ontario, is intended to be neither a biography of his career nor a eulogy of his life. His biography has already been written in an incomparable manner by Mr. T. A. Rickard, his eulogy by Canon Cody. What more can be said of Dr. Miller than is summed up in the words of that great Canadian divine, Canon Cody, that he was "Big in body, big in heart, and, as we learned, big in brain." This article, then, will merely record a few personal reminiscences of the man himself, and while they are necessarily disjointed, they may at least serve to illustrate certain traits in his character which are not generally known or appreciated outside of the circle of his intimate friends. In the latter part of May in the year 1904, Willet G. Miller, with two? assistants, set out for the small village of Haileybury to begin his geological work in the area a few miles to the south which he was soon to name Cobalt. At that time the Timiskaming and Northern Ontario railway was not finished, although the right-of-way was cleared and partly graded. The nearest railway station was on the Canadian Pacific at the south end of lake Timiskaming, from which point the old steamer Meteor carried passengers and freight up the long, narrow and deep waters of lake Timiskaming, a very pleasant trip of some sixty miles. On this particular trip there was a fairly large crowd on board consisting of settlers going into the clay belt north of lake Timiskaming, of lumbermen, and of a few merchants and commercial travellers who were interested in the small business centres of Haileybury, New Liskeard and Ville Marie. Scarcely any attention was paid to the reports of the newly found silver deposits, although the daily papers had announced discoveries in the district six months before. As a matter of fact, the chief excitement on board was afforded by a moose, which, in swimming from the Ontario to the Quebec shore of the lake, crossed the bow of the boat, the captain steering to within a few yards of the terrified animal.

Jan 1, 1925

By Ki-Bok Min, Seokwon Jeon, Seung-Beum Choi, Taehyun Kim

"In order to investigate anisotropic characteristics of Boryeong shale in Korea, which clearly shows transverse isotropy, a series of experimental tests were carried out. Using Brazilian test, five elastic constants and tensile strength of the shale were evaluated. Elastic constants were determined by iterative procedure and in order to perform this procedure, constitutive model was modified to fit the experimental condition. The anisotropic ratios of elastic constants were evaluated and the applicability of the methodology was assessed. Apparent Brazilian tensile strength profile was investigated and the ratio of the maximum to minimum tensile strength was estimated. Results showed that the tested rock type had low to moderate anisotropic characteristics.INTRODUCTIONMechanical, thermal and hydraulic characteristics of many rocks vary according to direction, which is known as inherent anisotropy, and it is originated from stratified and/or foliated structure of intact rock and discontinuity of rock mass. Anisotropy is one of the long standing issues of rock mechanics field and it has to be taken into account in several engineering fields such as civil, mining and petroleum engineering. An anisotropic medium has 21 independent elastic constants without any assumption of symmetry. If a material has any symmetry, the number of elastic constants required to define its behavior reduces and eventually two constants are necessary if it has complete symmetry, which is known as isotropy. An anisotropic medium that has remarkable planar structure due to its stratification and foliation such as bedding is often called as a transversely isotropic medium. Transversely isotropic model is frequently adopted in many applications especially for sedimentary rock formation and five elastic constants are required to establish the constitutive model."

Jan 1, 2015

By J. Zou

Open-cut method is most widely used for shallow utility lines installation. In urban areas, unexpected utility lines buried underground potentially turn open-cut construction into a highly risky operation, increasing the construction cost while presenting additional safety hazards. Examples include: breaking existing water main leads to flooding the downtown area; hitting an unexpected gas line causes an explosion. To prevent those accidents, the current practice is to stake out the underground utility lines before the open-cut construction based on the as-built information collected from various utility companies and government agencies. However, the as-built information is not always complete and accurate. To verify the locations of some important utility lines and protect them against damages caused by open-cut construction, new techniques and technologies are used but have their limitations in revealing underground utility lines, such as hydro vacuum method and ground penetration radars (GPR). The emerging technology of ultra-wide band (UWB) radar holds the potential to provide a cost-effective, non-destructive detection method. In this paper, a critical review of current practices and established methodologies is given. The functionality and working mechanism of UWB radar technologies are described. Application potential in open-cut construction is demonstrated by conducting lab experiments. Testing set-ups for detecting unexpected utility lines in soil along with preliminary results are presented. The effects of soil moisture content on the detection range are discussed. Research findings are summarized and constraints are discussed in conclusions.

Aug 1, 2013

By A. Torkian

Process water from production of concentrates in Meydook copper sulfide mine is transferred to the 8.3 million m3 tailings dam and a water retention pond after initial thickening. Elevated concentrations of heavy metals, sulfate, and TDS and decrease in pH as well as seepage into the aquifers have been the concern of the regulatory agencies since the start of activities. In this paper the results of a 6-month monitoring program from 4 wells are presented. The wells were located approximately 1.5 km from downstream of tailing dam (0.4 km from water retention pond) as well as upstream background well (2.28 km from water retention pond and 1.27 km from tailings dam). The objective was to study possible effect of accumulated tailings on the groundwater resources. Water levels in sampled wells were on average between 20 and 40 m. Results showed high levels of lead (5 ppb), copper (0.17-0.46 ppm) and selenium (73.1- 29.1 ppb). High levels of selenium and lead were partly due to natural geological settings of the area with high levels present in unaffected soils in the vicinity including water wells of villages upstream of mining operations. High copper levels were attributed to both mining operations as well as deposition from particulate air deposition onto the soil and transport to ground water by rain.

Aug 1, 2013

There are many inherent risks in creating a mine plan for a new ore zone in an underground mine; one of such risks is the redistribution of stresses that could be a cause of instability. Using numerical modelling tools, it is possible to model the planned stope extraction sequence and evaluate the influence of mining induced stresses on the stability of remnant pillars, and use this information to remedy potential setbacks. This paper demonstrates this approach through a case study of the short-term mine plan of the Lapa mine of Agnico Eagle Mines Ltd., an underground gold mining operation near Val d?Or. Three-dimensional boundary element modelling is used to compute the stresses induced by the stope extraction sequence as planned with a longitudinal retreat mining method. The proposed methodology can be generalized to other mines that require an understanding of the stress concentrations at the pre-feasibility stage of mine design.

May 1, 2009