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By J. Marks

The measurement of greenhouse gas (GHG) emissions from primary aluminium production and inventory of these emissions of carbon dioxide and PF Cs have become an important issue for primary aluminium producers. Most global producers have either voluntary emission goals or emissions limits established through national regulatory requirements. International good practices for inventory of these emissions for national governments are established through the Intergovernmental Panel on Climate Change (IPCC). The current good practices, last updated in 2000, are being revised and are expected to be adopted by governments in the spring of 2006. There are a number of changes expected in the guidance that will impact how facilities account for their GHG emissions. This paper describes the changes to the guidance and the implications of these changes for aluminium producers.

Jan 1, 2006

By Nural Kuyucak, Graham A. Johnson

Noranda's Geco Division is presently developing a comprehensive reclamation plan for closure of its Manitouwadge, Ontario operation, expected late in 1995. As part of a program of progressive rehabilation, the existing 20 year old water treatment plant will be upgraded from a low density to a high density lime neutralization process treating AMD and excess site water. The process, developed by the Noranda Technology Centre, utilizes a two step rather than a single step process to bring the Ph to the required neutralization level, a variation which contributes to improved sludge properties such as higher density and decreased viscosity. This is of particular significance where sludge pumping or storage volumes may present a concerns.

Jan 1, 1995

By Joseph Sawicz

By now, the concept of remotely controlling heavy equipment in underground mines has become commonplace. Personnel safety is the biggest justifier for remote control, followed by an inherent cost saving (in certain cases) when wireless video is added to the mix. There are a handful of vendors targeting this need, and for years the mines have remained loyal to their brand. But as the number of remote-control related accidents and maintenance costs increase it forces our industry to take another look at this commonplace concept. And as the blinders are taken off, the mines are getting the revelation that not all remote control systems were created equally. This paper highlights the differences between various remote control systems, and then moves into an in-depth look at HARD-LINE?s package which drastically cuts maintenance costs, and also provides a solid investment toward full Tele-operation.

Apr 1, 2005

By H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida

"In this study, flow-through experiments in fractured rocks have been conducted under different stress, temperature, and pH conditions so as to understand the evolution of permeability induced by these conditions. Throughout the experiments, the confining pressures and temperatures are well-controlled. Effluent concentrations are also measured for the ten elements of Si, Al, K, Fe, Ca, Na, Mg, Ti, S, and Cl that are included mainly in the targeted rocks. In the early stage of the experiments, the fracture permeability measured abruptly decreases with time, and subsequently reaches quasi-steady state within a relatively short period. In contrast, the permeability in the intact rocks monotonically increases with time. The permeability increase and decrease are attributed likely to the relative dominance of mineral dissolution in the pore spaces and to that of mineral dissolution/crushing at the propping asperities within the fracture and/or mineral precipitation onto the free surfaces, respectively. The evolving rates and magnitudes of the permeability are likely to be controlled by the stress exerted over the contacting asperities, temperatures, and pH of the permeant. Thus, this complicated behavior should be attributed to the coupled chemically- and mechanically-induced effects, which should be examined in more detail for longer period to contribute to the safe entombment of radioactive wastes. INTRODUCTIONUnderstanding of the flow and transport characteristics of porous/fractured rocks is required for the safe and long-term geological isolation of energy-related by-products (i.e., high level radioactive wastes and anthropogenic CO2). Notably, under relatively high temperature and stress conditions, mechanically- and chemically-mediated processes may alter the pore structures in rocks, resulting in an irreversible evolution of the flow and transport behavior. Augmentation in permeability may result from mechanical dilation due to shearing and mineral dissolution within the pore spaces, while reduction may result from reversible or irreversible mechanical compaction, mineral dissolution at the contacting areas, and clogging of pore spaces by precipitation of secondary minerals."

Jan 1, 2015

By Jayesh B. Patel, Zhongyun Fan, Hu-Tian Li

"Melt conditioned direct-chill (MC-DC) casting is a novel technology which combines vertical direct-chill (DC) casting with a high shear device directly immersed in the sump for in situ microstructural control. In this paper, the solidification mechanism of DC casting under varying conditions is discussed. The temperature profiles in the sump were measured under the steady state casting conditions by using sacrificing thermocouples. Detailed comparisons of the derived thermal condition are made. The individual role of grain refiner additions, natural thermosolutal convection and forced convection in the sump and the interplay of these factors in determining the solidification structures of DC cast billets are discussed. The MC-DC casting technology can be used to control microstructural constituents and casting defects in DC cast billets/ingots by in situ manipulating of the thermal and fluid flow conditions.INTRODUCTION Direct-chill (DC) casting of aluminium, has been the essential commercial process for producing feedstock suitable for subsequent processing, such as extrusion, rolling or forging. Fine and equiaxed grain structures in the as-cast billets/ingots are required to enable a fine and uniform distribution of second phase particles and microporosity. This leads to higher productivity, more cost-effective homogenisation and more efficient downstream thermomechanical processing. The addition of chemical inoculants has been the standard industrial operation prior to casting for grain refinement of Al alloys. However, it has been established that less than 1% of the grain refiner particles added actually act as heterogeneous nuclei to refine the grain structures, showing a very low grain refining efficiency (Greer, Bunn, Tronche, Evans, & Bristow, 2000). Moreover, the remaining particles from the grain refiner addition in the final casting may cause surface defects during downstream processing. A major issue of the metallurgical quality of large sized ingots/billets is the non-uniformity of microstructures even with chemical grain refiner additions. This is due to the fact that the grain structure formed in the different zones of the billet depends on the local chemical composition and local cooling rate. The local cooling rate can vary from 0.4~1 K/s at the centre of the billet to around 10–20 K/s at its surface zone (Nadella, Eskin, Du, & Katgerman, 2008). The large thermal gradient along radial direction between billet surface and interior of the melt during conventional DC casting induces thermal stress and cold cracking even with grain refiner addition. Therefore the control of casting defects, such as macrosegregation, porosity, cold/hot cracking and distortion of the billets/slabs, etc., is still challenging in industry, causing high scrap rate of DC cast ingots/billets even with grain refiner addition."

Jan 1, 2018

By Robin Phinney

Certain statements in this presentation may constitute "forward-looking" statements which involve known and unknown risks, uncertainties and other factors which may cause the actual results, pe1formance or achievements of the Corporation, or industry results, to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. When used in this presentation, such statements use such words as "may", "would", "could", "will", "intend", "expect", "believe", "plan", "anticipate", "estimate" and other similar terminology. These statements reflect the Corporation's current expectations regarding future events and operating performance and speak only as of the date of this presentation. Forward-looking statements involve significant risks and uncertainties, should not be read as guarantees of future performance or results, and will not necessa1ily be accurate indications of whether or not such results will be achieved. A number of factors could cause actual results to differ materially from the results discussed in the forward looking statements including, but not limited to, the factors discussed in the Corporation's annual information form filed on March 9, 2011. Actual results could differ materially from those currently anticipated due to a number of factors and risks. These include, but are not limited to, the failure to obtain necessary regulatory approvals, including environmental approval, the failure to secure full project financing, the failure to implement the recommendations set out in the Technical Report, the failure to raise financing to implement the recommendations in the Technical Report, risks associated with the mining industry in general (e.g., operational risks in development, exploration and production; delays or changes in plans with respect to exploration or development projects or capital expenditures; the uncertainty of estimates and projections relating to production, reserves and resources, costs and expenses; and health, safety and environmental risks), decrease in potash prices and exchange rate fluctuations. Although the forward-looking statements contained in this presentation are based upon what management of the Corporation believes are reasonable assumptions, the Corporation cannot assure shareholders that actual results will be consistent with these fonvard-looking statements. These fon\?ard-looking statements are made as of the date of this presentation and are expressly qualified in their entirety by this cautionary statement. Subject to applicable securities laws, the Corporation assumes no obligation to update or revise them to reflect new events or circumstances. This presentation is a market update based on the Corporation's public disclosure and does not form a part of any offer of securities, or constitute a solicitation of any offer to purchase or subscribe for securities. Any purchase of securities in the company should be made solely on the basis of information contained in the Corporation's public record which is available on www.sedar.com .

May 1, 2013

By J. E. Nesset

"As an alternative to conventional dewatering by vacuum filtration and oil-fired rotary dryers, Brunswick Mining conducted extensive pilot-scale testwork on its copper, lead, zinc and bulk concentrates using a Larox Oy (Finland) automatic pressure filter. The results showed that pressure filtration readily produced final cake moistures of 6-8.5 per cent on this very fine sulphide material.An in-depth analysis examines pressure filtration in terms of metallurgical performance and projects energy savings of 78 per cent for pressure filters over the current dewatering operation. Potential energy and operating cost reductions are also estimated.IntroductionVacuum filters followed by oil-fired rotary dryers are one of the most common means of dewatering mineral concentrates. They represent, however, a level of technology which is exceedingly wasteful in terms of manpower, space utilization equipment and fossil fuel dependence. In addition, the use of thermal dryers is leading to increased environmental concerns both in plant and out.These were the primary factors which prompted Brunswick Mining to consider alternative dewatering methods as the existing equipment came up for replacement and upgrading. In late 1979, company engineers were encouraged by automatic Larox pressure filters seen at several Scandinavian operations. Subsequent laboratory tests by the manufacturer (Larox Oy of Finland) on several concentrate samples were sufficiently promising for Brunswick and Noranda to lease a trailer mounted filter-lab unit and a technician from Larox for a five-week period. Extensive on-site testwork on all four Brunswick concentrates (zinc, lead, copper and 'bulk' lead-zinc) confirmed the potential of pressure filtration."

Jan 1, 1982

By Jeremy G. Berg, James B. Mulligan

"There is a very small fraction of wireless experts in the world with experience in underground installations and an even smaller fraction that have experience specific to building mine shafts. This is why in 2009, Redpath created its own system to meet the demands specific to shaft construction. Today, after a dozen shaft installations and several design iterations, Redpath has the expertise and experience required to implement a proper wireless system in any shaft configuration.This document will explain multiple proven wireless communication designs optimized for shaft construction and suitable for permanent use. This includes line of sight installations up to 1200m, short range mesh networks, and the latest patent pending Integrated Leaky Feeder Mesh Network. Additionally, this document will explore the lessons that Redpath learned in its effort to interconnect the people and tools needed to build a mine shaft.INTRODUCTIONAfter a decade of research, several design iterations and a dozen application examples, Redpath has resolved two wireless network architectures to best serve mine shaft construction projects.The long range line-of-sight (LOS) wireless network is the most cost effective and easiest to install, but requires an unobstructed line of sight between the working area and the shaft collar. As such, long range LOS is best suited for ventilation shafts or during the first phase of shaft sinking, before the shaft is equipped.Alternatively, a mesh network uses radios installed at pre-determined intervals in the shaft and on each conveyance. A wireless mesh uses antennas to bridge intervals between shaft radios, whereas Redpath’s integrated leaky feeder mesh network (patent pending) bridges these intervals with radiating cable, commonly referred to as a “leaky feeder” cable. Both of these mesh configurations can provide continuous reception for hoist conveyances travelling in shafts without line-of-sight, making them ideal for shaft equipping and even permanent installations in both mine shafts and lateral drifts.BACKGROUNDHoist operators receive operating commands using what are commonly referred to as “bell signals.” These instructions are delivered in a series of coded pulses on a spring returned pull cord or push button that is typically hardwired back to the hoist operator’s control room from one of many locations in the mine shaft. During the construction phase of a traditional mine shaft, a worker riding inside the sinking bucket would have to reach out to a pull cord installed on the shaft wall to send a stop command to the hoist operator. Today, Redpath’s modern shaft sinking projects use fully enclosed personnel carriers to protect the workers riding inside, specifically preventing workers from reaching out into the shaft while the hoist is in motion. The enforcement of this safety feature on all shaft projects in 2008 forced the engineering group at Redpath to find a suitable wireless solution for hoist communication to facilitate shaft construction.THE IDEAL COMMUNICATION SYSTEM FOR MINE SHAFT CONSTRUCTIONIdeally, the shaft communication system should not transform the tools to which the miners have grown accustomed. It should support the push-to-talk functionality of traditional VHF handsets and the standard belling system that has been used for decades. Additionally, it should be able to support a vendor independent framework upon which new devices and features can be added. The following paragraphs summarize some of the important requirements Redpath has identified.Support for voice transmission: Low latency is critical to prevent jitter during voice transmissions. The system must be compatible with commercially available mobile handsets and support several simultaneous conversations with the ability to broadcast a voice message to all users on a select channel using a “push-to- talk” microphone and loudspeaker.Transmission of PLC data: Low latency is required to"

Jan 1, 2019

By D. Cruden

DISCODAT is a system of computer programs written for CANMET, Canadian Department of Energy, Mines and resources, to be used in analyzing geological data for rock slope design. The programs were written in Fortran IV for an IBM 360/67 computer. A program conditions field data from field forms for storage in a line file. Data may be selectively retrieved from the line file by a general retrieval program which uses a variety of relational operators. The retrieved data may be displayed as structural diagrams or histograms produced on a line printer or in a number of maps produced on a drum plotter. There is a logical sequence which leads to the characterization of those elements of the subfabrics of a rock mass which may be kinematically active. Structural domains within the rock mass can also be outlined by a procedure described as areal analysis. Costs for a complete analysis are usually substantially less than $l/discontinuity.

Jan 1, 1978

By S. M. J. Mirazimi, F. Rashchi

Recovery of vanadium from LD (Linz-Donawits) converter slag was evaluated by means of microbial leaching. Vanadium leaching was performed in two stages. In the first stage, the bacteria were grown in a culture medium and in the second stage; vanadium containing slag was added to the metabolites produced by bacteria. Bioleaching was performed using heterotrophic bacteria Pseudomonas Putída. Control tests without bacteria inoculation were also performed and the results were compared with bioleaching outcomes. Optimal conditions for the bioleaching of vanadium containing slag were determined.

Jan 1, 2011

By Hongyan Qu, Lihui Zheng

"Horizontal wells in coal seams, Qinshui basin, China are prone to wellbore instability problems induced by drilling, completion and production operations due to the presence of natural cleat network, anisotropy with regard to permeability, brittleness and mechanically weak property of the coal rock. The mechanism of wellbore instability in coal seams is very different from that in conventional formations, the traditional wellbore stability study methods therefore, are not proper for wellbore stability analysis in coal.In this study, the mechanism and controlling of wellbore stability of coal seams in the Qinshui basin was investigated through theoretical modeling, laboratory experiment and field operation. Firstly, a new physical model of wellbore stability for highly-cleated coalbed was proposed, considering the combined effect of mechanical mechanism and reservoir characteristics, specifically, taking the effect of reservoir pore pressure in the vicinity of the wellbore on the wellbore stability into account. Then experiments on the triaxial stress evaluation were conducted at laboratory where rock mechanical parameters such as Poisson's ratio, Young's modulus, compressive strength, tensile strength, angle of internal friction and cohesion ability were measured respectively. The in situ stress at different depths in four wells of Zheng 1-303, Zheng 1-308, Zheng 1-309, and Zheng 1-310 in the Zhengzhuang were calculated, and the collapse pressure and formation breakdown pressure were predicted through the theoretical model we developed. Finally, by comparing the maximum collapse pressure and minimum breakdown pressure of the four wells in the coal as well as in the roof and floor of the coal seams, the fluid weight window for safe drilling in each coal seams was determined, and appropriate approaches against anti-sloughing in coal seams, Qinshui basin were applied in the field operation.The wellbore stability was found not only related to the wellbore pressure, but also affected by the pressure in the reservoir through the theoretical model. The fluid weight window for safe drilling in each coal seams varies with the coefficient of wellbore stability in the model. The laboratory experiment results indicate that the roof and floor of 3 # coal in Qinshui basin has high breaking strength, high heterogeneity, and are easy to collapse and breakdown. In addition, the whole rock mineral analysis shows that 3 # coal in the Duanshi block has high clay content, resulting in the phenomenon of hydration swelling as clay encountered water, and leading to unstable coal and extreme large drilling uncertainties. Due to the effect of the unstable rock mechanical properties of the roof and floor formation on the wellbore stabilizing, drilling parameters, drilling fluid performance and BHA were optimized during the drilling process according to the formation properties, rock mechanical properties and drilling techniques in the field operation."

Jan 1, 2015

By J. Gillies

"Those of you who were at last years C.M.P. meeting are aware there was discussion at that meeting concerning the best method of assisting the assayers of metal mines to exchange new ideas and methods of assaying. The opportunity to advise you of what came of that discussion is very much appreciated.There are several societies, including the Chemical Institute of Canada, the Spectroscopy Society and others that could be of some assistance to assayers. However, since these societies cover a rather broad field and not many mine assayers have the opportunity to attend their meetings, it was felt that an organization oriented to the specific needs of the mine assayers would be of more value to them.Several years ago an attempt was made to hold meetings for the benefit of assayers in conjunction with the Conference of Metallurgists held each year by the Metallurgical Society of the C .I.M.M. This did not work because very few of the mine assayers attended the meetings.With the very evident success of the type of meetings the C.M.P. have and the excellent groundwork done by your secretary, Mr. Stevens, in talking about this to mine management and assayers at many mines across the country, it was decided to hold a meeting at Noranda on October 8 to discuss how best we could help ourselves solve our problems.For the initial meeting it was felt that perhaps it would be better to start with a smaller group, so invitations were sent to mines in Ontario and Quebec that were geographically fairly close to Noranda."

Jan 1, 1970

By E. M. De Souza, A. M. Coode

"Since potash was discovered substantial rock mechanics research has been done to develop the technology needed to cope with the unique conditions in Saskatchewan mines, to assure general mine safety and to assess the problems associated with mining potash at depth.The practical result of this research was the development of multiple entry systems incorporating yielding pillars for access ways and the chevron type layouts for production panels. These developments proved the viability of extracting potash from between 950 m and 1100 m depth using a high degree of mechanization. High extraction ratios could not, however, be achieved using the developed technology.The presence of a competent salt back is critical to mining the potash, and underground practice is governed by the presence of anomalous geological zones. These factors may be associated with the occurrence of brine inflows. One potash mine in Saskatchewan ceased its underground operations and was closed due to flooding of the entire mine. Two other potash mines in Saskatchewan had significant brine inflows. The costs involved in brine pumping, equipment relocation, bulkhead construction, grouting, and in auxiliary operations can run into the tens of millions of dollars.At Central Canada Potash, the use of stress relief and yielding pillars in the design of the mining layouts has resulted in over-all stable underground excavations and safe mining practices. There are two types of production room s, the chevron and the hybrid, which result in a planned block average extraction ratio of 35010. Mining activity has resulted in brine ingresses in two areas, and additional operating costs have been incurred over the years. These mining areas have demonstrated abnormally high closure rates, and rapid back deterioration. A program was established in those two areas to ensure the practice of safe mining procedures.The short-term perspectives inherent in the program included the elimination of all uncertainties associated with the possibility of an increase in brine inflow leading to flooding, the elimination of the abnormal ground behaviour and ground deterioration in the inflow areas, and the reduction of the long-term adverse effects of mining on regional mine stability. The program was also designed to provide means for developing alternative safe mine layouts which would improve the exploitation of potash resources. Details of the extensive work performed during the program are found elsewhere (E. De Souza, 1988).Grouting and salt backfilling are viable techniques to control brine inflows in underground excavations in potash mines. Detailed instrumentation of the backfilled test areas provides information on the long-term behaviour and effectiveness of the grout/backfill system, allowing for rational decisions on the complete abandonment of these mined out areas, thus resulting in considerable operational cost savings.This paper is presented in two parts: the first addressed the problems of diamond drilling , grouting and backfilling in Panel 209 and the second, addresses the problems of instrumentation and rock mechanics."

Jan 1, 1990

By J. G. Whellock, R. J. Phillips, J. W. Matousek, P. J. Marcantonio

"Stillwater Mining Company (SMC), a partnership of Chevron Resources and Manville Corporation, produces a copper-nickel, platinum-palladium flotation concentrate at its Nye, Montana mine. The concentrate is then toll processed in Europe. Recognizing the economic advantage of treating the concentrates at the mine site and of retaining this strategic resource in the United States, the Company commissioned Tolltreck International Limited and International Process Research Corporation to conduct pilot scale smelting tests with a flowsheet that would maximize metal recoveries while satisfying the environmental requirements of operations at Stillwater.Primary smelting was conducted in a single phase, 50 k W, submerged-arc, electric furnace. Refining the product mattes to copper-nickel ""white-metal""; containing approximately 2% iron, was accomplished in a Tolltreck, IV-litre, top blown rotary converter. Over-all platinum and palladium recoveries were approximately 99%; copper and nickel recoveries averaged 94%. INTRODUCTION(l-4)Stillwater Mining Company (SMC) a partnership of Chevron Resources and Manville, operates a copper-nickel, platinum palladium mine and concentrator at Nye, Montana, located in the valley of the Stillwater River, approximately, 100 km southwest of Billings. It is North America's only primary producer of these precious metals. The Stillwater area was mined for chrome ore during World War U and the Korean War, but it was not until 1961 that attention was drawn to the similarities between the Stillwater Complex and the Bushveld Complex of South Africa with its deposits of platinum group metals.A concentrated search for platinum was begun by Manville Corporation in 1967. Its presence, together with palladium, in mineable quantities was confirmed in the period 1976-1978, and the first partnership to develop the deposits was formed by Manville and Chevron in 1979. Anaconda joined the group in 1983, and in 1985 its share was purchased by Lac Minerals. In 1988 the interests of Lac Minerals were purchased by Chevron and Manville.The decision to develop the mine and build a concentrator was made in 1986. Construction began in the fall of that year, and the first concentrate was produced six months later, in March 1987. Underground mining is done in a two-shift, five day- week operation. Since startup, the concentrator has operated on a 24 hour/day, 7 day/week schedule, treating an average of 635 tonnes of ore per day and producing approximately 10 tonnes of concentrate."

Jan 1, 1989

By M. M. C Jiménez, J. A. S Ténorio

For the recovery of valuable materials and for the protection of environment, recycling process of printed circuit board is an important subject of study. Moreover, the popularization of the computers and its technological evolution has generated a large number of waste electrical and electronic equipment. This paper presents a study of synergistic solvent extraction of copper, nickel and zinc from a sulfuric leaching liquor of printed circuit boards (PCB’s). The percent extraction of copper, nickel and zinc from dilute aqueous sulfate media besides synergistic effect of mixture of the .extractants Cyanex 272 and D2EHPA have been studied. Furthermore, different conditions such as temperature, pH of the feed solution have been examined. The results suggest that the synergistic effect of the .extractants mixture enhance the extraction efficiency of nickel.

Jan 1, 2014

By M. Jiang, X. Fan, W. X. Chen, Z. K. Guo, H. H. Zou

"Some improvements are carried out for elasto-plastic model by taking the shear dilation effects and relaxation effects of deep rocks into accounted. The high pressure equations of states with Mie-Grüneisen form are also introduced to describe the relation of pressure-volumetric strain. Numerical simulations of free field responses for deep underground explosions are conducted by using the user subroutines which compiled by means of the secondary development functions of LS-DYNA9703D codes. It is indicated that the dynamic responses of free field are well simulated based on this improved elasto-plastic model, and the analytical results are in good agreement with the data of U.S. Hardhat nuclear test.INTRODUCTIONDynamic behaviors of deep rocks for underground explosions are obviously different from that of shallow underground explosions and have aroused great attentions of international experts who work for rock engineering. The dynamic models of deep rocks could be roughly divided into classic elasto-plastic model and fracture damage model according to different theoretical foundation. M. E.Kipp and D. E.Grady et al. are the outstanding representatives who engaged in the researches of fracture damage mechanics. Researches of dynamic problems for geomaterials were carried out by C.C.Grigorian and the conclusion that incompressible elasto-plastic medium model could not be used to solve the problems of closed underground explosion was derived, and therefore C.C.Grigorian model was proposed. In this model, C.C.Grigorian assumed that the average hydrostatic pressures and the densities of medium had one to one relationship, and the path of loading or unloading is different from each other. For shear deformations, analytical solutions of the problems were derived according to the model which was slightly different from Prandtl-Reuss model, the constitutive equations were closed by Mises-Schleiher constitutive model. However, the analysis showed that there were two inadequacies in C.C.Grigorian model. Firstly, the shear dilation effects of fractured medium after wave front could not be considered. Secondly, the relaxation characteristics of the rocks in fractured region were not taken into account."

Jan 1, 2015

By J. A. Finch, M. Mimezami, M. S. Hashemi A.

The adsorption of magnesium and calcium ions on sphalerite and pyrite is discussed. These ions are common in process water and often considered be detrimental in sulphide flotation. The study attempts to characterize the adsorption mechanism, which has been less studied than the oxide system. Generally for oxides metal ion uptake occurs when cations are hydrolyzed. Our findings reveal that magnesium and calcium adsorb on sulphides at pH below hydrolysis, but adsorption is not chemical. At higher pH, charge reversal occurs that does correspond to presence of hydrolysis products. Advances

Jan 1, 2009

By Jie Zhu

Coal bumps are a special form of release of geologic strain energy that has already been one of the most dangerous hazards to underground mining safety in China. A number of coal-bump models have been developed to quantify coal failure under assumption that a bump is a kind of non-gas induced outburst. However, some technical experts in charge of micro-seismic and gas monitoring have found unusual gas emissions before and after bump, which suggests that it is possible for gas to trigger coal bumps. Considering the coal reservoir as geological body composed of the coal matrix and gas, a new model based on Lippmann?s bump model is proposed to understand the initiation of coal bumps. The redistribution zone from excavation of a roadway has been calculated and analyzed regarding its relation with mining depth. It is shown that high gas pressure may push the coal seam to overstep the critical state due to extension of the plastic disturbed zone, and this is harmful to the stability of coal seam. This model successfully explains the bump phenomena of the Xinzhouyao mine at shallow depth.

Aug 1, 2013

By J. E. Dutrizac, J. B. Sunstrum

"Lead was among the first metals known to man, and there are indications that lead was produced by the reductive smelting of galena in the mountains surrounding the Black Sea as early as 3000 B. C .(1). The early metallurgists soon discovered that silver could be recovered from lead bullion by cupellation techniques, and that the litharge product of the cupellation process could be reduced to give silver-free lead metal. By the Graeco-Roman era, lead-silver ores were being extensively exploited for both their silver and lead contents. Although silver was always of prime concern, a number of industrial uses existed for lead that included piping and sheeting. Subsequently, lead metallurgical practice developed steadily in different parts of the world, and was a relatively mature technology by the time of the European colonization of North America. In the United States, lead was produced on a small scale as early as 1720, and by 1800, the extensive Pb-Zn deposits of Missouri-Kansas and the upper Mississippi Valley were being developed(2). Many of the early American lead ores were low in silver, and seemed to have been worked primarily for their lead contents. Major uses of lead at the time included bullets, pipe and sheeting. During the period 1860-1890, the silver-rich galena ores of the western United States were exploited, and a number of lead smelters were operated. Although all the smelters produced lead metal, the recuperation of the associated silver and gold values was generally of prime concern. In Canada, lead deposits are abundant, and galenarich outcrops frequently attracted the attention of the early explorers and prospectors. In fact, the first record of a Canadian ore deposit seems to have been the observation of an argentiferous galena vein near Lake Temiscamingue in 17 41(3). The presence of silver-bearing lead deposits naturally attracted the attention of the mining community, and many outcrops were worked throughout the country. Because of the problems associated with transporting lead concentrates to existing American or overseas smelters, attention soon shifted to the establishment of local lead smelting facilities. The purpose of this article is to examine those early smelting efforts and to try to identify the first ""successful"" Canadian lead smelter."

Jan 1, 1999

By Gary M. Bone

The autonomous control of vehicles interacting forcibly with their environment, such as dozers and tractors, is an unsolved and challenging problem. Forces and motions are inherently coupled between the tool and the means of vehicle propulsion. Furthermore, they are often operated within uncertain and unstructured environments, such as those encountered in underground mining. There is a growing industrial interest in the development of robotic vehicles to improve productivity, efficiency and safety in mining and construction. This paper focuses on the modeling and control of autonomous robotic dozing for a material removal operation. A dozing process model has been developed based on observations of both a fullscale dozer and a scaled-down version. The model characterizes the dynamic interactions between the blade position, material accumulation on the blade, material distribution in the environment, and the motions of the dozer. The dozing control objective is to remove the loose material as rapidly as possible by driving forwards at full power while automatically raising/lowering the blade in response to sensor measurements. Two different controllers were developed to meet this objective. The first controller is based on a set of heuristic rules, and the second is an optimal controller based on the dynamic model. An instrumented scaled-down robotic dozer and dozing environment, designed to emulate the full-scale operation, are used to implement the controllers and compare their performances over multiple dozing passes. Experimental results are presented showing that the model-based controller increased the material removal rate by 33% compared to the rule-based controller. Lastly, technologies for full-scale implementation are discussed, followed by proposed future work and conclusions.

Aug 1, 2013