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By Chuan-liu Wang

The bionic non-smooth surface has the characteristics of anti-wear, and reducing resistance. Based on bionic non-smooth surface?s characteristics, a bionic drill bit was developed. When the bionic drill bit is used, a bionic non-smooth surface forms on the crown of bionic drill bit. This surface can be used to extend the life of drill bit and improve drill efficiency. The bionic unit diameter and arrangement were researched in this paper to determine the optimal bionic non-smooth surface for further improving the life and efficiency of drill bit. Four bionic samples having the same structure size, materials and arrangement were designed and manufactured. After being sintered, the abrasion ratios of the four bionic samples were tested, and the results show that the abrasion ratio of Nos. 3 and 2 were similar (only 2% difference) and higher than that of No. 1 and 4. Therefore, the optimal diameter of bionic unit is 1.5 and 2.0 mm. Small diameter bionic drill bits were designed and manufactured, and tested in the laboratory. The results show that not all bionic structure bodies are better than normal diamond bits, except the bionic unit arranged in a reasonable range. When the angle was 24° and 30°, the arrangement of bionic unit were more reasonable, which shows the superiority of the bionic coupling bit.

Aug 1, 2013

By J. D. Wright

This paper describes current milling practice at Endako Mines Ltd., a molybdenum producer in central British Columbia. The various steps in the crushing, grinding and flotation of the ore are outlined, with emphasis on the metallurgy of the latter operation. Tailings disposal and concentrate assaying methods are also described.

Jan 1, 1969

By F. Chiesa

Experimental results on thin and thick castings poured in aluminum A356 and magnesium AZ91E by the low pressure permanent mold process have been compared to the result of filling simulations for thin and thick castings. If the results of modeling is reliable when the liquid remains above the liquidus temperature, this is no longer the case when partial solidification occurs. The visco-elastic behavior of a partially solidified liquid is difficult to put into equation as it depends on the amount of shear it has been been subjected to. Attempts to predict misruns with a commercial software has been proven to be very difficult if not impossible; divergence of the numerical solution has been observed unless prohibitively long computing times are used. In order to overcome these difficulties from a practical standpoint, a simple method is proposed which consists in tracking the temperature of the advancing liquid metal front so as to make sure it will always be above so-called `Misrun Critical Temperature' (MCT) determined experimentally for thin and thick aluminum A356 and magnesium AZ91E castings. If the liquid metal front falls below this temperature, a cold-shut or misrun is likely to happen at this location. The values of MCT for thin and thick in aluminum A356 and magnesium AZ91E were determined experimentally on misrun castings of extreme geometries (a thin 2.5 mm wall cover and a 6mm to 25 mm thick bell housing). MCT was found to be lower for magnesium AZ91E and for the thicker castings.

Jan 1, 2011

By J. L. Huisman, G. Schouten

After pyrometallurgy and hydrometallurgy, bio(hydro)metallurgy is the latest development in the ongoing search for efficient and economic metal winning processes. In addition to bioleaching, other biotechnology-based applications are getting more and more accepted. In this paper a number of proven and commercial processes will be presented that can be applied for nickel and cobalt recovery and refining. These processes are based on the ability of biomass to convert the redox state of sulphur compounds under ambient conditions. They can be applied to recover sulphate from effluents or SOx from off gases and convert it to H2S or dissolved sulphide that can be reused in production or effluent treatment. Not only does this minimize the costs on resources but it also reduces waste production and improves the quality of discharges even to the point where reuse becomes feasible.

Jan 1, 2005

By R. P. van Hille, N. Mooruth

Remediation of acid rock drainage (ARD) was performed within a linear flow channel reactor (LFCR) via a floating sulphur biofilm (FSB). A full sulphur species material balance was conducted in order to characterize the sulphide oxidation. The reactor was able to achieve an 82% and 93% conversion of sulphide with a hydraulic residence time of 2 and 5 days respectively. 92% and 55.5% of the converted sulphide reported to the biofilm as sulphur for the 2 and 5 day residence times respectively. The mass transport limitations within the biofilm were identified via a dissolved oxygen gradient profiling system.

Jan 1, 2011

By H. W. Smith, R. D. Fournier

This paper presents the results of an investigation of a full-scale rod mill. Appropriate numerical techniques are developed for the experimental determination of the parameters of a dynamic mathematical model from steady state data. The results confirm that this full-scale rod mill behaves similarly to laboratory-scale ball mills for which results have previously been obtained. It is noted, however, that although the model presented is adequate for predicting over-all particle size distributions, the size distributions of individual components of a multicomponent ore cannot be predicted.

Jan 1, 1972

By Y. Nara, N. Aramaki, M. Maruyama

Evaluation of three dimensionally non-uniform strain distribution in rocks under various conditions such as in water or under freeze-thaw cycles is of significant importance to understand their complex deformations and fracturing mechanisms. For this purpose, we developed an image analysis method which can evaluate or “measure” the three dimensional (3-D) strain distribution in rocks. The proposed method utilizes the 3-D images of rock under initial and deformed configurations, which are obtained by some imaging techniques such as X-ray computed tomography (X-rayCT). In the proposed method, the obtained 3-D images are divided into multiple sub-regions of interest. For each sub-region, the strain is evaluated utilizing 3-D affine transform with unknown coefficients to be determined. In the first step, 3-D voxel level displacements at multiple representative points in each sub-region are computed by 3- D digital volume correlation technique between the comparison images and the initial-guess of the transform coefficients are obtained. In the second step, referring to the initial-guess of unknown transform coefficient, they were optimized in sub-voxel level by finding optimum digital volume correlation between the comparison images, which can evaluate the transform coefficients with higher precision. From the calculated transform coefficients, the strain was directly obtained through the spatial derivative of displacement based on affine transform. In this paper, along with the description of the proposed method, the evaluation of deformation in a lignite specimen due to immersion in water was presented as an application example. As the 3-D imaging technique, micro-focus X-rayCT was applied. The result showed that the induced dilatational strain field due to the initiation and extension of cracks in the specimen was clearly captured. Therefore, authors believe that the proposed method can be applicable to various problems in rock mechanics.

Jan 1, 2015

By K. Thuro, L. Wilfing, H. Kasling

"In mechanized tunneling, performance prediction is a crucial issue for estimating excavation costs and construction time of a tunnel project. The aim of this work is to compare the calculated parameters by penetration prediction models with the results of penetration tests during excavation by a Tunnel Boring Machine (TBM) at actual tunnel projects. This comparison helps to improve the existing prediction models (Gehring, 1995 and Rostami (Colorado School of Mines), 1997.) and to develop a new, so-called “Alpine Model” (research group ABROCK; Schneider et al., 2012).On-site penetration tests are a common tool to determine performance of a TBM in certain geological environments. During a test, the TBM is operated under defined conditions that allow comparing the results of different projects and machine types. There are two different types of penetration tests in use. The more common type, described by Bruland (1998a), is based on test drives at different thrust levels. The tests in this study are performed as start-stop-tests, meaning that the TBM starts from zero to the maximum possible thrust and reverse with slowly increasing respectively decreasing steps (Frenzel et al., 2012). To gain information about the interaction between TBM and rock mass, a detailed geological documentation including an analysis of the discontinuity pattern and laboratory testing for rock strength characterization are mandatory.Within the last year 16 penetration tests have been performed. The results are thrust- penetration curves (Figure 2) showing that up to a certain penetration rate only crushing occurs (subcritical penetration). From there the desired rock fragmentation process called chipping takes place (Frenzel et al., 2012). These two different fragmentation processes can be described best by a bilinear function as seen in Figure 3. Both, CSM- and Gehring-model, do not fit to the trend of the penetration rates determined during the excavation process as they are using potential or simple linear functions.Another parameter that has to be implemented into the new prediction model is the influence of discontinuities. In case of favorable orientation and spacing, discontinuities reduce the required thrust at same penetration rates. In contrast, unfavorable discontinuity systems can cause blocky faces and hence worse performance than predicted. Besides discontinuities, the toughness of rocks has to be taken into account when predicting the penetration as tough rocks need more energy to obtain complete failure than brittle rocks.Key advantage of these tests in comparison to existing are more data points in less time. By improving respectively extending the existing penetration prediction models with the stated parameters, the penetration prediction for TBMs can be more accurate and also wear calculation can benefit from this approach."

Jan 1, 2015

By Richard W. Lawrence, Richard Poulin

"Numerous processes co-exist for metal extraction and for metal removal from effluents of mining operations. Each process enjoys an economic advantage, including environmental cost and benefit, if utilized in a specific situation. This applies equally to biohydrometallurgical processes. This paper will analyze four types of biohydrometallurgical processes for their economic and environmental attributes: biooxidation of refractory gold, extraction of copper from sulfide, metal removal from effluents by active sulfate reduction, and metal removal by the use of wetlands. By examining the economic and environmental advantages of these processes, generalizations can formalized and it becomes possible to define niches of application where biohydrometallurgy can be considered. Our analysis shows that biohydrometallurgy can be efficient at small scale, be more environmentally friendly than conventional technologies and is relatively easier to operate. The higher financial risk associated with unproven technologies at the commercial scale is being eliminated as biotechnology-based plants are put into production.IntroductionBiotechnology can be described as the rational exploitation of the activities of living cells or parts thereof, requiring an integrated multidisciplinary approach between biological and technical disciplines. Microbiology, biochemistry, botany, molecular biology, chemistry and engineering all contribute to practical applications in the extraction, manufacturing and service industries, and in environmental management. Considerable commercial success of biotechnology has been achieved in several sectors, including health care, agriculture, forestry and aquaculture.Over the past 40 years, industry, research organizations, government laboratories, and universities in a large number of countries have participated in investigating the utilization of biotechnology applications in mining. Today, several technologies are used commercially in well understood and engineered systems which can be grouped under the term biohydrometallurgy. Many more technologies have been demonstrated at laboratory or pilot plant scale. Although initial developments and commercial applications were aimed at metal extraction, the dramatic increase in environmental awareness, the practice of sound environmental management demanded by more stringent regulations over the past decade, and the need for low cost treatment in perpetuity, has led to serious investigation of biotechnology for environmental control. In addition, increasing power costs, lowering of ore grades, and decreasing commodity price in real dollar terms require the use of highly efficient and competitive extractive technologies."

Jan 1, 1998

By Eugene Barsky

"At present, theoretical concepts of gravitational separation processes are mainly limited by the study of the interaction between a flow and a solitary particle. Then the main conclusions of this analysis are applied to a mass process. However, this analysis is absolutely insufficient, because some elementary phenomena such as the ingress of coarse particles into the fine product output and vice versa cannot be interpreted from its standpoint. It is also impossible to predict the results of the classification of a material with a specific granulometric composition on a specific apparatus on its basis.In the present paper, an extended model of the process is suggested. The model is based on the behavior of all the particles of a specific narrow size class, and not on that of an individual particle. Similarity criteria of the process, which were empirically derived previously, are obtained from the analysis of this model.INTRODUCTIONIn case of gravitational separation, a part of solid phase moves, as a rule, vertically upwards with the flow, while another part settles against the flow. This flow is extremely complicated and chaotic due to various random factors. Among these factors are mass interactions of particles with each other and with the apparatus walls, non-uniform character of concentration and velocity fields, turbulent vortices and local fluctuations, real particles shape difference from spherical one, etc.Particles rotation results in a transverse force (Magnus' effect). At the motion of a non-rotating particle in a non-uniform velocity field, a transverse force also arises (Saffman's effect).A great number of publications have been devoted to the account for all these factors in two-phase flows in recent decades. Very complicated models have been developed, but the problem has not been completely solved as yet [1, 3].At the same time, simplified models of the behavior of a solitary particle in a flow are being developed. Despite their schematic nature, such models often prove to be useful for establishing general laws of the process and its similarity criteria [1]."

Jan 1, 2016

By Y. Feng

Perovskite structured oxide 15% Y-doped BaCeO3 (BCY15) has been evaluated for use as proton conducting electrolyte in SOFC with propane as the fuel and Pt as both electrodes. Under the fuel cell conditions, BCY15 exhibited high proton conductivity and good cell performances. Propylene was detected as product at the anode outlet, and the product distribution suggests that propane dehydrogenation underwent competition with cracking to lighter hydrocarbons. Stability during cell performance tests showed that there was no obvious degradation for BCY15 electrolyte during operation of C3H8-O2 fuel cell.

Jan 1, 2005

By Charles Amoah

Abosso Goldfields Limited has been optimizing the comminution circuit at the Damang Mine Operation for the treatment of 100% primary ore. The optimization process started at a base rate of 343 tph when treating primary crushed primary ore, and was increased to above 600 tph with partially crushed primary ore. Abosso Goldfields engaged Orway Mineral Consultants (OMC) to assist with the optimization process in 2009 and the two companies have been working together since, to further refine the process. Continuous improvement was achieved through crushing circuit modifications, changes in operating processes and grinding control system utilization. This paper discusses the improvements developed for the increase in milling capacity and improvements in final product size.

Jan 1, 2012

By Xiqing Wu, Liang Dai, Tao Yue, Longsheng Yi, Ruifang Wang

Magnetic seeding flotation (MSF), i.e. adding magnetic seeds and pre-magnetization-flotation, is a new flotation technology especially for fine particles, which improves the flotation performance by enlarging the apparent size of the particles in a way of magnetic agglomeration. Both the fine coal slimes with a size of 66.68% –38µm and the pyrite slimes with a size of 73.95% –23 µm were investigated by the MSF, respectively. Flotation tests with variable of dosages of magnetic seeds and polyacrylamide were conducted, and some measurements, such as laser diffraction size analysis, magnetic susceptibility by vibrating sample magnetometer (VSM) and infrared spectroscopy (IRS), were also applied in order to probe the mechanism of the MSF. Based on the tests, measurements and calculations it was found that both the recovery of coal and the flotation kinetics of pyrite slimes increased with the additions of the magnetic seeds, and in the presence of polyacrylamide the coal flotation was further strengthened due to a synergetic effect of magnetic seeds and polyacrylamide on the flotation and a relatively larger apparent size of slimes after additions of magnetic seeds and polyacrylamide. The reason for the MSF lies in fact that the presence of the polyacrylamide intensified the adsorption of magnetic seeds on the coal particles and increased the coverage of the magnetic seeds on the coal surface from 0.2 to 1.3 wt%, resulting in increased magnetic susceptibility of coal particles from 9.13×10-9 to 22.17×10-9 m3/kg and thus a low magnetic field strength of pre-magnetization needed for the magnetic agglomeration among the coal particles from 602 to 24 mT prior to proper flotation. IRS shows that polyacrylamide chemisorbed on the surfaces of both coal particles and magnetic seeds, thus acting as the bridging media between particles and seeds.

Jan 1, 2016

By Adrian E. Scheidegger

"AbstractThe possibilities of deriving pertinent information about fractures in an oil pay from data obtained by core analysis are investigated. It is shown that it is possible to obtain an estimate of the fractured area per unit volume of the pay, and that the size of the fractures can be estimated if their shape is known. A suggestion of a routine procedure for the analysis of fractures is given.1.-IntroductionMany oil fields are producing essentially from cracks or fractures. Where this is the case, it is important to be able to obtain a knowledge of the size and distribution of those fractures in the oil pay. This knowledge has to be derived from the analysis of cores taken from the fields, as it is generally impossible to follow a fracture through the pay by direct means. The necessity of using statistical methods to extrapolate the meagre information obtained from the cores of the wells is therefore indicated.It is known that the fractures are much bigger than the diameter of the cores; thus, if they strike a core, the latter will generally fall into two pieces. The angle of the fracture with the vertical can be measured and, if oriented cores are taken, the exact position of the surface element representing the intersection of the fracture with the drill stem can be determined. Sometimes the edge of a fracture can be seen in a core. The number of •Cores that show such an edge can be noted. Of course, one has to be careful to distinguish between original fractures in the pay and fractures in the core caused by drilling operations. Only the former are relevant."

Jan 1, 1955

By Mark Holdsworth

In 2002, Kennecott Utah Copper Copperton Concentrator installed an Expert Control system for optimization of their SAG and Ball milling circuits. The advanced process control has been well received and is utilized well over 95% of the time. In the years since, many lessons have been learned and many advances have been made. Improvements have produced millions of dollars of benefits and have included directly controlling feedrate with complex logic as opposed to using a bearing pressure controller, modifications to how sound is used for control, modifying logic for maximizing asset utilization and using advanced control for automating equipment restart.

Jan 1, 2012

By D. Bai, F. Hamad, S. Abraham

For the integrity of welded structures such as pipelines, the toughness of the heat-affected zones (HAZ) is an important property. This property is often specified in terms of Charpy V-notch (CVN) impact toughness and determined by the standard test method. An experimental study has been conducted in an industrial laboratory to measure the impact toughness of the coarse grain heat-affected zones (CGHAZ) of an X80 line pipe material. The field girth welding conditions in terms of heat input were simulated, together with special edge preparation to improve the targeted testing of the CGHAZ. The effect of toughness of the neighboring regions, in particular the weld metal, on measured impact toughness of the CGHAZ was investigated. The fracture paths of the CVN tested samples were examined by both optical and scanning electron microscopy. The deviation of segments of the fracture path into the weld metal was found to have a significant effect on the measured impact toughness of the CGHAZ.

Jan 1, 2005

By W. Beres, M. Bielawski

Recent research on the development of erosion resistant coatings has been directed to the finite element modelling of the behavior of coating and substrate, and their interface under the impact of eroding particles. The approach presented in this paper is based on advanced computer simulation techniques using ABAQUS/Explicit to investigate stress and strain at the surface and at the coating/substrate interface of multilayer coatings under single particle impact. It was found previously that solid particle erosion mechanisms are predominantly governed by the kinetic energy of the impacting particles. However, recent modelling efforts revealed that effects of various material models could be also significant. Therefore, different material models representing relevant coating and substrate properties were investigated and the effects of these models on the coating/substrate response were studied. Particularly, differences between elastic, elastic-plastic and brittle cracking model responses were assessed.

Jan 1, 2006

By G. C. Laurence

"This paper discusses the hazards and extensive precautions taken in Canadian uranium mines, concentrating plants and processing plants. It also outlines Canadian policy regarding the control of the sale and distribution of uranium and other nuclear materials.OVER THIRTY YEARS AGO, I spoke to The Canadian Institute of Mining and Metallurgy here in Montreal about radioactivity and its dangers. I must have made quite an impression thirty odd years ago, because now you have asked me to do it again. Of course, the picture has changed. Then they were mining uranium ore, recovering the radium from it and throwing away the uranium. Now they are still mining uranium ore, but are throwing the radium out on the tailings dumps. Thirty years ago, most people did not know what ""radioactivity"" meant. Nowadays, they have beard that it is dangerous, and some of them, recently, be-came worried about the radium in the tailings dumps and what becomes of it."

Jan 1, 1969

By N. Tounsi

The use of analytical modeling of continuous chip formation in conjunction with orthogonal cutting experiments was presented in the open literature to identify the coefficients of material constitutive equation within the practical range of stress, strain, strain rate, and temperature encountered in metal cutting. Identification of reliable constitutive data was hampered by a lack of a reliable model for the prediction of the primary shear zone thickness that affects directly the effective strain rate field. An original analytical model to determine the primary shear zone thickness is proposed in this paper. It is based on the mechanics governing the material flow in the primary shear zone. Based on the distribution of the hydrostatic pressure and the forces measured from orthogonal cutting tests, the model that describes the thickness of the primary shear zone is derived. To validate the model, FE simulations of chip formation using DEFORM3D were carried out for different materials and cutting conditions. The results of the analytical model are in reasonable agreement with FEM results.

Jan 1, 2006

By Ellis Thomson

The microscope is now used extensively not only in the examination of solid ore but also in the determination of fragmental mill products. It has therefore become a matter of paramount importance to be able to mount and polish fragmental as well as solid specimens in the easiest and most efficient way, so that the minerals present may be readily determined. In the case of the solid ore the ordinary mount of plasticine set on a glass or metal slide serves for most practical purposes. An improvement on this is furnished by the small brass container inside of which the specimen is mounted in a cementing medium of sealing wax. The latter is the method in use at Harvard University. It has the advantage of uniform height, thus obviating the necessity of a slide of any sort. It is also easily catalogued as the brass holder may be stamped with a convenient series of letters and numbers that will serve as a label. Other advantages of this type are the ease with which any particular part of the section may be re-located, the excellent storing facilities afforded by mounts of uniform size, and the possibility of polishing ten or a dozen sections at the same time by means of a holder which is placed over the polishing wheel, is geared with it, but revolves the opposite way.

Jan 1, 1926