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By A. M. Elmahdy, T. Hirajima, M. Farahat

"Separation of molybdenite from chalcopyrite is mainly achieved through flotation technique to raise their grades up to 25% to be extracted in smelters. However, molybdenite recovery and grade obtained from this process is not satisfactory in most cases due to the natural hydrophobicity of both minerals. The influence of conventional heat treatment on pure chalcopyrite and molybdenite minerals was investigated. X-ray diffraction, TG-DTA and XPS techniques were applied before and after heat treatment. The results showed phase changes for both minerals. Magnetic separation experiments of single and mixture of both minerals at several magnetic intensities were made. For single mineral experiments, 100% molybdenite recovery was obtained at all experimental conditions as non-magnetic fraction whereas ca. 100% chalcopyrite recovery was achieved under certain conditions. In case of 1:1 binary mixture, 87% and 83% molybdenum and copper recoveries, respectively, were obtained. The increase in chalcopyrite magnetic recovery is related to the formation of more magnetic phases as confirmed by characterization techniques.The objective of this study is to increase the magnetism of chalcopyrite to make its separation from molybdenite by magnetic separation possible and to understand the mechanism behind it. These results indicate that it may be possible to upgrade molybdenite ores using heat treatment followed by magnetic separation to the required grade by smelters which is difficult to attain by froth flotation and the other techniques."

Jan 1, 2016

By Kathy S. Kalenchuk

Damages have been observed in shafts, backfill infrastructure and the slick line at the Leeville Mine. Shaft damage (shearing and spalling of the concrete liner) is attributed to mine-induced rock mass deformations concentrated where regional faults intersect the shafts. Aggregate bin, mixer station and conveyor drive damage (shotcrete shearing, heave of concrete floor slabs and bending of a vertical steel beams) is attributed to rock mass squeezing induced by elevated magnitudes of the vertically orientated major principal stresses. Separation of the slick line has occurred do to extension of the stressshadowed rock mass immediately above the mined out areas. Three-dimensional numerical models have been developed and calibrated to simulated rock mass deformations with magnitudes similar to those believed to have produced the observed damages. By stepping through the mine sequence, models reproduce deformations at the same mining stage as when damage has occurred. Calibrated models have been used to forward project further damage over the remaining mine life.

Jun 1, 2012

By Kazutoshi Haga, Batnasan Altansukh, Yasushi Takasaki, Mohd Yazid Bin Abdul Razak, Atsushi Shibayama

"In this study, the volatilization behaviour of arsenic (As) and antimony (Sb) from arsenicantimony bearing minerals such as tennantite (Cu12As4S13)/tetrahedrite (Cu12Sb4S13) in copper ore was investigated using a roasting process. Specifically, the thermal decomposition of tennantite and the arsenic volatilization were investigated under nitrogen and air atmosphere. The roasting experiments were performed at temperatures ranging from 500 to 1,200oC and different retention times using a laboratory electric furnace. The results indicated that over 95% volatilization was achieved at 700oC. On the other hand, when the temperature increased to 1,200oC, volatilization rate of Sb reached to 90%. Therefore, volatilization of Sb requires high temperature compared to As. It suggests that As and Sb can be separated using temperature difference. Selective removal of As is possible at 700oC, subsequently Sb can be recovered as a volatilized product by increasing the temperature to 1,200oC. Meanwhile, volatilization of Cu and Fe was not observed on these conditions. The content of As and Sb in the residues obtained from roasting at 700 and 1,200oC was less than 0.3 and 0.75 mass%, respectively. The Cu content in solid residue at 1,200oC increased to 34 mass%. The clean copper concentrate with lower amounts of arsenic and antimony was obtained from the process. INTRODUCTIONRecently, arsenic (As) and antimony (Sb) contents in copper (Cu) concentrates are increasing year by year. Arsenic and antimony are present with Cu minerals such as enargite (Cu3AsS4), tennantite (Cu12As4S13) and tetrahedrite (Cu12Sb4S13) that associate with copper sulfides [chalcopyrite (CuFeS2) and bornite (Cu5FeS4)]. They are normally concentrated by flotation and treated in copper smelters. However, treatment of copper concentrates containing high amounts of arsenic and antimony by a smelting process is difficult due to environmental implications of toxic arsenic and antimony. As demand for copper continues to grow, the need to source copper from several types of resources including those that contain high levels of As/Sb becomes necessary. Therefore, a novel processes for the treatment of As/Sb bearing Cu concentrates are required. Reviews on copper resources such as enargite, tennantite and tetrahedrite containing high amounts of arsenic and antimony are covered widely in literatures by many researchers (Padilla et al., 1998; Welham, 2001; Vinals et al., 2003; Guo & Yen, 2005; Balaž & Achimovicova, 2006a; Filippou et al., 2007; Mihajlovic et al., 2007; Lattanzi et al., 2008)."

Jan 1, 2016

By M. Fairclough, B. Moldovan

Insights into uranium mining projects of the future can be gained by a careful statistical analysis of past and present deposits, as well as an examination of recent trends for uranium resource evaluation and primary uranium production. The International Atomic Energy Agency (IAEA) provides the necessary data and corresponding mechanisms as inputs for methodologies that enable strategic and scientific evaluations of long-term security of supply uranium required to sustain the demand for nuclear fuel. Sustainability of the uranium mining industry and subsequently new uranium mines of the future requires innovation and expertise to lower operating costs, maintain or improve uranium recovery while meeting the requirements of stakeholders in regard to protection of the environment and safety of the workers and general public.

Jan 1, 2020

By V. Labiouse, F. Orellana

"Hollow cylinder samples can be tested for both the characterization of rock properties and the physical modelling at reduced scale of engineering applications. Particularly, this type of experimental setup can be used to simulate different stress conditions around underground openings, as already developed in the petroleum engineering field e.g. to study the instabilities around deep wellbores during either drilling or the oil production phase. Some authors have also used this technique to successfully characterize the damaged zone around underground openings in the tunneling engineering field looking for an efficient design of their support.This article presents a new hollow cylinder testing device developed at the Rock Mechanics Laboratory of the Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland. It allows a full and independent control of the confining pressure and pore water pressure conditions at both the inner and outer boundaries of Thick-Walled Hollow Cylindrical samples. In order to mimicking a tunnel excavation in a porous rock mass, after initial recovery of the in-situ stress and pore water pressure, the hollow cylinders are subjected to a decrease in the internal confining pressure. Moreover, X-Ray Computed Tomography scans of the specimens are performed through the testing cell before and after the mechanical unloading to monitor the displacements undergone and the sample damage. The equipment, testing procedure and data analysis techniques are briefly presented in the paper.The good performance of the apparatus has already been checked on weak rock specimens, among others on Boom and Opalinus Clay samples. In many configurations, the mechanical unloading is found to induce a Damaged Zone (DZ) around the central hole. Its geometry and extent show a great similarity with in-situ observations around tunnels driven in the Boom and Opalinus Clay formations. Such similarities contribute to increase confidence in the understanding and modelling of the ongoing processes."

Jan 1, 2015

By Gregory C. More O'Ferrall

Generally pillars in the Southern African hard rock tabular underground mining environment are designed using either empirical pillar design formulae or numerical modelling (analytical) methods utilizing the Hoek-Brown failure criterion. However, none of the pillar design methodologies employed takes cognizance of weak layers either within the pillar material or in the immediate foundation of the pillar. Over the past few years, the presence of a weak layer either within the pillar material or within the immediate foundation of the pillar has resulted in the closure of one platinum mine (Everest Mine), closure of one chrome mine (Wonderkop Chrome) and large-scale instability in a couple of chrome and platinum mines in South Africa and Zimbabwe. A study has been initiated to better understand the failure mode and strengths of the pillars where pillar failure associated with weak layers occurred. Owing to the infancy of the study into the failed pillar strength and failure mechanism, the purpose of this paper is to highlight the circumstances that led to the collapse of mining sections and a shaft, and the difficulty associated with designing pillars in the Southern African chrome and platinum mining operations.

Jun 1, 2012

By J. B. Yianatos, F. A. Contreras

Mineral carrying rates across the pulp-froth interface in the range of 1.4-3.2 tph/m2 and bubble surface coverages between 7 and 22 %, have been determined in large rougher flotation cells operated under normal conditions. To evaluate these variables, measurements of bubble size distribution, bubble load and size distribution of particles collected by true flotation, were performed at different concentrators. A model for estimating the bubble surface coverage at the pulp-froth interface level as a function of bubble load, Sauter mean bubble diameter and particle size distribution of the mineral collected by true flotation, was developed. Bubble loadings in the range 24-70 kg/m3, bubble sizes between 1.5 and 3.2 mm and superficial gas rates between 1.2 and 2.0 emfs, were measured in copper rougher flotation cells under normal operating conditions. Estimated bubble surface area fluxes were in the range 31 to 62 cm2/s/cm2- Results of carrying rates and bubble surface coverage, at the pulp-froth interface, were significantly lower than the maximum carrying rate for the collection zone, indicating that in this case is difficult to achieve maximum carrying rate at the pulp-froth interface level. The main constraints regarding carrying capacity limitations are then related to the froth transport characteristics (i.e. cell design, froth residence time, froth stability, froth recovery). Advances in Mineral Processing Science and Technology Proceedings of the 48th Annual Conference of Metallurgists ofCIM Sudbury, Ontario, Canada Edited by

Jan 1, 2009

By P. G. Lazenby

This paper describes the latest instrumentation improvements in the INPUT Airborne E.M. System, particularly the new electronic signal-processing techniques. Several anomaly examples illustrating these techniques are shown.

Jan 1, 1973

By R. Loj

Katowice Coal Holding (KHW) is one of the largest coal companies in Europe. The company owns five coal mines with a daily output of around 60 000 tons of coal. In the Katowice city area, very good quality steam coal is extracted. The depth of mining varies between 400 and 1100 m and some of the mines rank amongst those most afflicted by methane in the Upper Silesian Coal Basin, with the methane hazard having a significant impact on production and safety. ?Myslowice-Wesola? mine, being a part of the Katowice Coal Holding is characterized by high methane and rockburst hazards. The mine is equipped with a modern surface drainage pumping station. At the mentioned mine, longwall 514 was selected for analysis of its methane emission. The longwall was extracting the thick seam 501 (over 4 m), at a depth of over 900 m, which was subject to high stress and high gas concentration conditions. At a distance of about 50 m above, seam 501 is covered by thin seam 416. The strata between these two seams are sandstone and mudstone layers. In the floor of seam 501, with a thin shale interlayer, is located seam 510, which is the thickest (over 10m) and richest coal seam in the Upper Silesian Coal Basin. In longwall 514 and it?s vicinity, methane was the dominant risk. For this longwall three methods of classical gas drainage were carried out. At first, drainage was undertaken using long boreholes from a cross-cut at level 665 m, located far from the production panel. Later, it was performed using typical boreholes drilled from the ventilation gallery (tail gate road). Finally, it was undertaken using a degassing drift executed in the upper coal seam 416. All of these headings, ie. cross-cut level 665 m, the ventilation road and conveyor road in seam 501 and the degassing drift in seam 416, were equipped with media for drilling and proper drainage pipelines. Due to the high rockburst hazard and some problems with caving, several kinds of de-stressing and torpedo blasts were carried out in both coal seams and roof rocks. The subsequent analysis and experiments allowed the establishment of some general rules for carrying out degassing operations effectively. The effectiveness of a degassing drift was demonstrated. In some instances, the system allowed more than 70% of the total methane released to be captured and fed into pipelines. The aforementioned blasts had a marginal impact on methane emissions and the efficiency of degassing methods. Cyclic drilling and regular switching of boreholes in phase with the mining progress and working face advance were shown to be essential.

Aug 1, 2013

By C. O. Campbell

THE recognition by C. W. McKee, field engineer for Springer Sturgeon Gold Mines, Limited, in the fall of 1940, of the economic possibilities of a small outcrop of baryres near Pembroke, in Hants county, Nova Scotia, followed by aggressive exploration and development by the Company, has placed Canada for the first time in its history in the position of becoming a major producer of barytes and its products. In past years, production of this mineral in Canada has been unimportant. Thus the coral output from 1885 ro 1933, inclusive, amounted to only 41,027 short tons, following which there was no production until 1939. Deposits in Nova Scotia, and particularly in the Lake Ainslie district, Cape Breton, have been the main source of supply, with a production between 1866 and 1925 of 31,689 tons. Following the examination of the outcrop of baryres near Pembroke by Mr. C. W. McKee in October, 1940, the area surrounding it was trenched, and, as this work gave encouraging results, a diamond drilling programme was commenced. A grid system was laid our and sixteen holes aggregating 2809.3 feet were put down, spaced at 100-foot intervals, the deepest hole being 300 feet. This drilling outlined a body of high-grade baryres over 600 feet long and 200 to 250 feet wide, with an average depth of 120 feet and estimated to contain well over one million tons of ore. The limits of the body were reached on the west, north, and southwest, but the drilling was suspended before the eastern limit was determined. Quarrying operations, and construction of a 100-ton mill, were commenced in February, 1941. The mill was placed in operation on May 29th, and on June 15th, eight months after the initial discovery, the first shipment of 2,500 long rons of milled baryres was made to Trinidad, British West Indies.

Jan 1, 1942

By T. C. Murphy, W. Taciuk

In 1966, the Iron Ore Company of Canada commissioned a wet magnetic scavanging plant for the recovery of fine magnetite values p.resent in spiral tailings discharged from a spiral gravity separation process. The plant includes dewatering, grinding, classification, thickening, mini-wedge screening, and primary, secondary and tertiary wet magnetic separation stages. The source of feed varies in quantity and quality, so the original design included variable operational procedures to deal with these conditions.

Jan 1, 1972

By A. Zhecheva

A commercial titanium alloy Ti-6Al-2Sn-4Zr-2Mo has been gas nitrided in this work, in pure nitrogen atmosphere in order to improve its surface properties. The nitriding was performed at two different temperatures, 950 and 1050°C, and for different periods of time. The influence of the initial surface roughness on the diffusion process and on the surface properties of this material was studied. The influence of the processing parameters of gas nitriding on the surface roughness, phase modifications and the microstructure of the nitrided layers has been analyzed using atomic force microscopy (AFM), X-ray diffraction and optical microscopy. Microhardness profiles were obtained on cross-sections of the samples after gas nitriding applying a Knoop indenter.

Jan 1, 2004

By H. S. Fowler

The Consolidated Mining and Smelting Company has been in the business of mining and exploration since its incorporation in 1906. The Company has reports written as early as 1890. Consequently, its files contain a very large number of reports, and also of maps, of ail descriptions. REPORTS Before describing the filing of maps, a brie{ note on our general system of filing reports will perhaps clarify the discussion. Reports of a non-periodic nature, primarily those based upon examinations by field engineers, are separated from all other data and filed in what we know as the Mine Series System. Each property on which reports are written is given a serial number, known as the Mine Series Number. This serial number is assigned at the time the first report is filed and it remains permanently identified with the property, regardless of its state of activity. Our mine series numbers now total over 5,000. The serial number for a property may be found by referring to an alphabetical index of properties. MAPS We found it necessary to divide maps into two groups: (1) Maps of properties (2) Maps of areas

Jan 1, 1944

This paper describes results of an investigation of fracture during tube expansion of 5052 and 5754 aluminum seam-welded tubes to optimize the forming of aluminum tubes during hydroforming. The tubes were produced in laboratory by press forming of tubular blanks and pilot-scale high frequency induction welding. The effect of property mismatch between the weld and base metal has been investigated. The material work-hardening was obtained by roll forming of sheet blanks in the 0-temper and H32 temper condition. The results showed that a significant work-hardening can be present in aluminum tube without causing weld fracture during tube expansion. The work-hardening increases the yield-strength mismatch between base metal and weld. Annealing reduces the hardness of base metal leading to more uniform deformation during tube expansion. As a result the occurrence of weld fracture is reduced. The study showed significant deformation of the welds during tube expansion. Weld thinning can be as large as parent-material thinning before fracture. To avoid fracture at the weld joint, good formability and high yield strength of the weld is needed. FEM simulation showed that minimizing the width of the weld joint can reduce thinning of the weld.

Jan 1, 2004

By Saba Gharedash

In this study the results of a series of numerical simulations which are conducted for one of the tunnels of the Mashhad metro line 2 project are presented to evaluate the role of tunnel face support pressure and soil strength parameters on deformation of tunnel lining and face deformation. To achieve this goal, comparative numerical simulations of a mechanized tunnel advance in soft non- homogeneous soil on top of the ground water table and beneath the building are conducted and sensitivity analysis is performed. Development of a step by step tunnel construction process is modeled using a three dimensional finite difference model (FLAC3D) taking into account all the relevant components of shield tunneling. In order to understand the mechanism of the effects of a variety of support pressures on face deformation and lining stresses, numerical simulations are conducted. It is found that the use of different face supports causes a considerable influence on the forces of tunnel lining. In addition, it is revealed that building weight help to change the stress paths and the stress distributions in the tunnel lining.

Aug 1, 2013

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 S. J. Cook

Outstanding advances among the metals, marked the mineral production records for Canada during the first half of 1925. Production of metals and non-metals reached a total value of $90,347,698. as compared with $84,307,385. in the first half of 1924, an increase of 7.16 per cent. Metals and non-metals produced during the calendar year 1924 were valued at $17 4,202,537.; production during the first half of 1925 showed a sum equal to 51.86 per cent of this total. Advances among the metals were general. Gold rose to a new record. Lead advanced 62.41 per cent over the high mark attained in the first half of 1924. Nickel production was well maintained. Copper was up a million pounds. Silver showed increased values. Zinc followed the trend in lead to almost double the output recorded in the first half of 1924. Cobalt production continued to improve. Despite the loss due to the protracted strike in the Nova Scotia coal mines which reduced the output of coal in that province; during the six months ending June, to less than half the tonnage reported in the first six months of 1924, improved conditions throughout the rest of the non-metal mining field resulted in the production of non-metals during the half-year reaching a total value of $31,199,233. as compared with $36,844,286. in the first half of 1924; the loss in the value of coal output al one amounted to $5,723,873, while the decrease in the aggregate value of non-metals amounted to only $5,645,053.

Jan 1, 1925

By J. P. Harrison, R. Roostaei

"In this paper we investigate the consequences of using conventional triaxial peak strength criteria in the polyaxial stress conditions that occur around the end of a long circular underground opening. A series of 3d boundary element analyses were performed using Examine3D to determine the stresses induced around the tunnel in different in-situ stress conditions. To discuss the applicability of a triaxial strength criterion in failure prediction, strength factors were computed for both the Ottosen polyaxial strength criterion and the triaxial Hoek-Brown criterion. Assuming that the Ottosen criterion is an accurate indicator of strength factor, the discrepancy from this value due to the Hoek-Brown criterion is the error in prediction.In order to simultaneously show the error in prediction and actual strength factor, a quantitative bivariate colour scheme is used to visualize the results. This allows rapid identification of regions with large error, and where either unsafe or overly conservative conditions occur. We show how the inappropriate use of triaxial criteria rather than polyaxial criteria leads to an under- or over-estimation of strength factor, and can result in uneconomic or unsafe design. Extending the analysis to different in situ stress regimes shows how the in situ stress conditions affect the assessment."

Jan 1, 2015

By G. M. Brownell

A DEPOSIT of hematite occurs on Black island, lake Winnipeg, at a point known locally as Red Rock, on the south shore of the island directly across from Clements point. The mail boat from the Canadian Pacific Railway terminus at Riverton, crossing the lake to Manigotogan twice weekly, passes near Red Rock and provides a convenient means of transportation to this part of Black island (Figure 1). HISTORICAL The occurrence of hematite on Black island has been known for a long time. Dowling's report of 1898 states(1): "An iron-ore deposit on the south side has been known' for many years, and on Jeffrey's map of 1762, showing Canada and northern part of Louisiana, Iron island is shown a short distance south of the narrows, evidently the same as the Black island of today".

Jan 1, 1945

By A. Moyano

The development of the traditional converting process performed in a PeirceSmith or Hoboken converter is limited by the investment magnitude associated to the fulfillment of the environmental regulations. Thus, the continuous converting process rather than a conceptual process alternative is becoming a necessity for a smelter facing limited converting capacity and/or lacking of fulfillment of the environmental regulation with its maximum converting capacity. The objective of this paper is to present the progress of the Codelco continuous converting process evaluated at pilot-scale level when converting solid mattes or white metal into blister copper. These tests allowed for gathering of relevant data to be considered for a new stage of evaluating the Codelco continuous converting at industrial-scale test. The pilot-scale tests were done in a Teniente Converter pilot scale unit at the Codelco Norte Smelter. The results of processing solid copper mattes (65-75% Cu) and producing low sulfur content blister copper with production of a constant S02 gas concentration, and the production of liquid slag with low copper solubility was achieved and is discussed in the present paper.

Jan 1, 2007