Search Documents

By L. Tang

A seismic monitoring system was installed in 2005 at Dongguashan Copper Mine, the deepest metal mine in China. Based on the seismic events monitored in situ, the possibility of rockburst prediction and prevention is investigated in this paper. The characteristics of space-timeintensity of mining-induced seismicity and the seismic response to mining are studied in detail using the seismic data in Dongguashan Mine. A conceptual model and a criterion of assessment of hazard seismic nucleation are proposed for Dongguashan Mine. In this model, the mine seismic stiffness method is adopted for rockburst prediction within the framework of the unstable failure theory. To analyze rock failure cases in Donggauashan Mine, the rate of the ratio of stiffness of rock in nucleation area to its surrounding area is proposed as a criterion for rockburst prediction.

May 1, 2009

In this study, flotation of fine galena, chalcopyrite and pyrite was performed after grinding with different extent of oxidation-reduction condition adjusted by grinding media. Sodium dithionite and iron ions were added in mill to simulate pulp potentials and iron oxidation species produced by grinding media, respectively. The types and quantities of the metal oxidation species on mineral surfaces were determined by EDTA extractions, while the surface electrical properties of minerals and interaction of different types of metal oxidation species were studied by zeta potential measurements. It was found that the nature and concentration of the absorbed metal oxidation species were dependent on oxidation atmosphere controlled by the iron amount of grinding media. These species interacted with each other and had an important role in determining flotation of fine galena and chalcopyrite as well as activation of fine pyrite by lead and copper.

Jan 1, 2006

By K. Becerra, D. G. Almond, T. D. Maru

"Nkomati Nickel Mine in South Africa processes one of the world’s hardest ores in a 375k TPM autogenous grinding circuit. The plant employs an unconventional processing circuit, comprising a primary autogenous mill (AG or FAG) and pebble crushing circuit followed by a secondary hybrid pebble/ball mill and classification cyclone cluster.Advanced Process Control (APC) or Expert Control is now generally accepted as an advantage in most modern high capacity concentrator grinding circuits. This paper reviews the installation of model predictive control at Nkomati and examines the results and benefits of installation in an autogenous mill during plant ramp-up. The paper also demonstrates how predefining process control objectives together with good plant and supplier cooperation can achieve a robust and reliable APC implementation on a very short site program.The results conclusively demonstrate operational and economic benefits during circuit operation with the advanced process control system ON. Production performance and circuit stability were significantly better than during manual control."

Jan 1, 2012

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

By E. R. Rivenbark

"The coal handling plant represents an investment of about $100 million in coal handling and storage equipment. The coal receiving is done by a continuous ship unloader that can handle ships in the 60 000 T range at Q rate of 1750 /ph. A unique feature in the system is a stacker/reclaimer unit which will work inside a dome storage structure. The coal for the unit will include any low sulphur coal that can be delivered by sea at an economical price blended with New Brunswick high sulphur coal.ThE flue gas scrubber is a wet limestone system capable of 95% SO2 removal. The scrubber will utilize about 150 000 tonnes of limestone per year and will produce commercial grade gypsum by the forced oxidization method.IntroductionWith the need for new generating capacity being required, New Brunswick Power reviewed, in 1985, its options for the next unit. The study indicated that the most attractive option for New Brunswick Power would be a coal-fired unit capable of receiving imported coal at a sea port. The site selection process resulted in three site options being considered.The existing Coleson Cove and Dalhousie sites, and the Belledune site were considered. To meet load distribution needs, it was then decided that the unit had to be located in the northern section of the province, thus eliminating the Coleson Cove site. The Belledune site was selected because it had the capacity to have additional units added where as the Dalhousie site would have only been able to accommodate one unit"

Jan 1, 1994

By Makarinskym F. M.

"This paper describes mechanical and operating modifications that were and are being made to current on-line flotation cells at Falconbridge Nickel Mines concentrators. Improved metallurgical performance and metal recoveries of some 3·4% over the past ten years are the end result of the modifications made. The paper acknowledges the contribution of operating, technical and maintenance personnel and the Company ""suggestion plan"" program. 1. INTRODUCTIONFalconbrirdge Nickel Mines Limited, incorporated in 1928 is a major product of nickel, copper,coba1t and other metals and minerals. The Canadian Nickel Division operating facilities in the Sudbury Area currently includes seven mines, two concentrators, and a smelter.For many years at all concentrators, improv0mcnts in metal recoveries have been continually under investigation. One area was to improve the flotation cell performance. This paper will deal with mechanical and operating modifications to the cells at the Strathcona and Falconhridge Ni-Cu sulphide concentrators, at the Sudbury Operations.One of the prime means to mineral beneficiation processing has been, and will continue to be, the basic froth flotation cell. The efficient operation of a flotation cell is the key to satisfactory metal selectivity and recovery. The essence of good design is simplicity. Changes to cell design can contribute to a significant improvement in metal recovery.Over the past 10 years, modifications to the flotation cells have contributed to an improvement of some 3-4” in mineral recovery. Providi11g tl1c initiative for improvements include operating, maintenance and technical personnel, as well as the employee suggestions submitted th1·ough the Suggestion Plan Program."

Jan 1, 1982

By Franz Simon

Conventional fine gold electrolytes for barrel applications working electrolytically actually permit significant precious metal savings by corresponding optimizations but the most gold is still deposited on areas of the components where it is not absolutely essential for the desired bonding and soldering applications, i.e. in high current density areas. Therefore an electrolyte working electrolessly has been developed which inevitably leads to a much more uniform thickness distribution since in an electroless process there are no areas favoured by metal deposition and current distribution. The new electrolyte will be presented and its performance will be compared with conventional electrolytes as regards thickness distribution. The potential gold savings will be discussed.

Oct 1, 2003

By Zia Pirzada

"Time is of the essence" and "Time is money" These are powerful and true statements during a project life cycle and have far-reaching implications on the success and failure of the project Time and progress management is crucial to the project success. Project delays may increase the cost to an unacceptable level and may render the project as economically unfeasible. On the other hand, if the project is completed on time or earlier than as planned, it may generate economic benefits greater than what had been envisioned To take advantage of the financial opportunities and to improve the cash flow as well as Return On Investment (POI), project schedule can be accelerated to complete the project earlier than planned Project schedule acceleration can be achieved by using analytical tools, such as "Schedule Optimization", "Schedule Reduction", "Schedule Compression" or a combination of any of these concepts along with the "Planning for start up". Schedule optimization does not entail any extra cost, however, other acceleration methods, such as Schedule Reduction and Schedule Compression, may require extra expenditures from the owner. Based on the forecasted early start of the revenue stream, the extra expenditure could become a worthwhile venture with a very high rate of return To accelerate the schedule, all aspects of the project should be reviewed with acceleration costs calculated. All risks and opportunities should be evaluated and taken into consideration to determine if the acceleration is feasible and advisable and will provide definite financial advantages Sometimes schedule acceleration may be desired to prevent the company from paying liquidated damages. This is especially true when the project is not expected to complete on the contractual completion date and when the cost of acceleration is less than the liquidated damages that may accrue against the company.

Oct 1, 2010

By Dougla McDonald, Richard Poulin

"Most mine managers in Canada today will agree that one of the keys to mining efficiency and productivity is their human resources. A5 a result, many mines develop some sort of incentive designed to tap their employees' capabilities to the fullest extent. Historically, the most common plans used have been ""piece-rate"" plans, where individual or small groups of miners are paid a financial bonus based on some measure of their productivity. Recently, however, incentive plans that take a more team-based approach have been developed in some Canadian mines. One such plan will be defined in this paper, and its popularity in the industry today discussed.Gainsharing PlansThere are two primary components to a gainsharing plan. The first is a cash incentive, which is paid to all employees and based on factors that are highly correlated with employee productivity, and key to the profitability of the mine. For example, the typical gainsharing cash incentive is based on the cost/unit of metal produced. Management (in consultation with employees in some cases) will establish the budgeted cost per tonne, and any savings in this amount is shared between the company and the employees. The second is a management philosophy and associated communication network, which is designed to foster an environment that encourages information exchanges, communication, participation, and trust between employees and management. The typical gainsharing communication network consists of two tiers of committees. The first, operational committees, include all employees working in the same department or departments which frequently interact. The employees meet monthly with management personnel to discuss problems encountered and brainstorm for solutions. In most cases, these committees will nominate a person in the group to structure the meeting to maximize its efficiency. The second, the screening committee, is a single group consisting of representatives from the various operational groups, whose primary job is to ensure that the plan is effective, and the objectives and results generated by the plan remain consistent with the mine objectives. In short, gainsharing plans tell employees that their bonus depends upon performance and then gives them the opportunity and incentive to affect that performance. The opportunity is provided by a communication network and positive management practices, and the incentive comes in the form of ""intrinsic"" rewards of participation and the ""extrinsic"" rewards of the bonus payments. Figure I will clarify the relationship between the intrinsic and extrinsic rewards."

Jan 1, 1995

By J. Ji, A. Shi, B. Grcic

Floating copper minerals selectively against iron minerals such as pyrite has been challenging for most copper and copper/gold deposits, and many operations continuously strive to maximise copper recovery whilst meeting target concentrate grades. Maximising grade is achieved by selectively floating copper minerals and rejecting pyrite. This challenge is to minimise copper and gold losses in the roughers if this approach is used. A flotation testing program was conducted by Bureau Veritas Minerals on a high-level pyrite bearing copper/gold ore sample to establish the potential to reject pyrite in the rougher stage, but also maximise copper and gold recoveries, and ultimately final product grades. The test program included feed characterization, rougher and open-circuit cleaner flotation as well as locked cycle flotation tests. The main variables tested for achieving selective flotation of copper and gold were collector type and pH control, through lime addition. Grind sizes used in the rougher and cleaner tests had been established from previous test work. The collectors tested were SIPX, Aerophine® 3418A, Aerophine® 3421, Aerophine® 3422, Reagent S-11192 Promoter, Reagent S-11193 Promoter and FloMin C4150. The two best performing collectors were then tested in open-circuit cleaner tests, with the optimum conditions examined further in locked cycle tests. INTRODUCTION Bureau Veritas Minerals Metallurgical Division was retained by Eldorado Gold Corporation to perform a metallurgical testing program on a high-level pyrite bearing copper/gold ore sample from a gold- copper porphyry deposit to optimize flotation reagent scheme to improve gold and copper recoveries and copper content in the concentrate. The test program included feed characterization, rougher and open-circuit cleaner flotation as well as locked cycle flotation tests. Initially, various collectors were screened in kinetic rougher tests, and over a pH range of 8.5 (i.e the natural ore pH) up to 11.5, using a primary grind size of 80% passing 120 µm. The collectors tested were SIPX (sodium isopropyl xanthate), Aerophine® 3418A, Aerophine® 3421, Aerophine® 3422, Reagent S-11192 Promoter, Reagent S-11193 Promoter and FloMin C4150. The enrichment ratio, which is the ratio of copper to sulfur in the concentrate to that in the feed, was used as proxy for rating selectivity (i.e. degree of pyrite rejection or depression).

Jan 1, 2019

By A. Kozlowski

We present research on cable fault location methods for mines where coal dust and methane explosions are a frequent potential hazard. The methodology and devices for low- and medium voltage cables fault location are well known and applied in classical power distribution networks. They are based on solutions for underground mines with a high risk of explosion. The lack of a safe solution for the location of a fault has contributed to the initiation of a research project by a group of Polish companies. The consortium consists of research institutes (Institute of Innovative Technologies EMAG, Tele and Radio Research Institute, Central Mining Institute GIG-KD ?Barbara?), Silesian University of Technology and a private entrepreneur MARTECH PLUS. Fast and exact determination of fault location is one of the important factors for minimizing power outage time. The lack of technical solutions to obtain measurements in a secure way leads to the use of the methods connected with a high risk of explosion. For example, the application of high energy can lead to arc discharge where there is a fault in insulation, creating the risk of an explosion. Measurements of methane concentration along the analyzed section of the cable reduce the risk; however the shock wave generated by the electric arc may raise coal dust and make an explosive mixture, which is an object of ignition. Low energy methods, like those based on reflection waves, have low sensitivity for high- and medium-resistance faults. This technique has difficulties in joints, which create false echoes. The fundamental problem is to determine the topology of the network using a reflectogram and find anomalies of a different nature ? not only open and short circuit. Included in the scope of the project is an analysis of Polish legal regulations related to fault location and operational work for low- and medium-voltage networks. Two of the methods used on the surface were selected as feasible to implement under explosion hazard conditions. In the process of development of the fault location methodology, installation features characteristic of underground mines were used, namely access to the whole length of a cable. This is the attribute that provides an opportunity to do measurements that are usually not possible for typical surface power nets. To carry out laboratory tests, a dedicated measuring stand with various types of cables was built. The authors describe the principle of operation of the fault locator and the results of the laboratory tests carried out on the cables with built-in damage (prepared for tests). Results of the work will be the basis for the next stage of the project associated with operational analyses of the prototype.

Aug 1, 2013

By F. Musuka, D. Jenkins, A. Keyes

BHP Olympic Dam operates a Direct-to-Blister copper flash smelting Furnace (DBF) and an Electric Slag Cleaning Furnace (ESCF). Tapping blister copper from these furnaces via tapholes is a routine task carried out by trained personnel. Blister tapping is a high-risk activity with personnel operating in close proximity to molten metal. BHP’s risk management framework has identified taphole integrity as key to managing the potential for loss of molten metal containment and molten metal – water steam explosion, both of which have the potential to cause multiple fatalities. As part of the focus on managing this risk, since 2017, a dedicated Taphole Development Team has been embedded in the operation to run an accelerated improvement program focused on safely and sustainably embedding an improved taphole design with greater integrity. The program of works includes selecting and testing of new materials as well as improving operating discipline by collaborating with tapping personnel to convert their knowledge into codified condition monitoring and operating strategies. Computational fluid dynamics (CFD) is being used to derive critical risk controls, and to develop live-alerts to infer excessive refractory insert wear. To date, improving DBF blister taphole mudgun clay has led to more consistent drilling depths and subsequently reduced oxygen lancing requirements, resulting in improvements in taphole insert service life. On the ESCF, insert performance testing and development of a new taphole condition monitoring strategy, is being used to increase taphole insert tonnages to more sustainable levels. Operations personnel have been closely involved in different phases of the change management, this has led to standardization of tapping practices for both furnaces, and improved ownership of the proposed changes. The paper discusses the maturity in taphole integrity risk management as a result of recent and ongoing developments. It then provides an overview of future taphole developments proposed at Olympic Dam. INTRODUCTION Tapping operations at Olympic Dam and learning from significant events The Direct-to-Blister furnace (DBF) at Olympic Dam was built with a conventional design blister taphole, which was designed for manual oxygen lancing and clay stopper bar plugging tapping operations (Campbell, 2005). Manual tapping is a high-risk activity, where personnel work in close proximity to molten metal, and molten metal personal protective clothing and equipment must be used. Opening tapholes by oxygen lancing is a skilled activity and unintentional damage to the taphole inserts can occur. Since 2008, a Mudgun and Drill unit has been developed and trialled and is now in use on the DBF blister tapholes, to remove personnel from the line of fire when opening and closing tapholes. This has the additional benefit of reducing lancing damage to taphole inserts. A new taphole design labelled the Modular Blister Taphole (MBTH) was developed at Olympic Dam for the Mudgun and Drill operation. The intent of the design was for mudgun clay to fill the entire tapping channel when plugging after a tap. The drill would then drill through this clay plug to open the taphole.

Jan 1, 2019

By Y. M. Shneerson, I. V. Fomenko, M. A. Pleshkov, E. A. Ospanov, A. A. Shakhalov, S. S. Naboychenko

Low-grade copper concentrates (with copper content less than 20%) often contain impurities such as arsenic, zinc, lead, mercury, antimony and bismuth. The pyrometallurgical treatment of such concentrates is associated with several problems, which will ultimately affect the cost and the quality of copper cathodes as well as by-products. SRC Hydrometallurgy proposed a complex hydrometallurgical technology which allows the removal of impurities and the enrichment of low-grade copper concentrates to a quality which will be more suitable for pyrometallurgical processing. Laboratory batch tests and pilot plant results for the pressure leaching steps are shown in this paper. The key parameters of the leaching steps were determined and optimized. The quality of possible by-products were also determined. The developed flowsheet includes two pressure leaching steps: pressure oxidation (POX) and hydrothermal alteration (HTA). Both operations are carried out at 170°C with subsequent flotation of POX and HTA residues and recovery of copper, zinc and lead into separate concentrates for further processing. The development of the flowsheet was based on the Balkhash Zinc Plant (Balkhash, Kazakhstan), which had been non-operational since 2009. The developed flowsheet for processing of low-grade concentrates will utilize 80% of the existing equipment of the Balkhash Zinc Plant, thus leading to a significant reduction in required capital expenditure. INTRODUCTION As the age of copper mining operations advance, copper grades continue to diminish and impurity levels increase. Therefore, copper producers are forced to look for new innovative hydrometallurgical technologies which are able to handle low-grade raw materials and solve problems associated with impurities in an economically justifiable way. New technologies allow to extract valuable components selectively and to process low-grade concentrates which had previously been marked as non-technological and economically unviable. Hydrometallurgical technologies for processing of copper-containing materials can be divided into two main categories: chloride and sulfate (atmospheric, autoclave and bacterial) based technologies. Since the 1970s, many autoclave techniques for the processing of copper-containing materials have been developed and implemented (Naboichenko, 2002; Dreisinger, 2005; Habashi, 2009; Shneerson, 2011). The mineralogical composition of the ore (or concentrates), geographical location of the deposit, distance from industrial areas, availability of existing treatment facilities, availability of skilled labor, cost of electricity and cost of neutralization are some of the factors which are usually considered when the appropriate technology is selected (Halbe, 2002).

Jan 1, 2019

By E. Lehtila, J. J. Talja, R. Jahila

Kopar Oy is acknowledged for engineering and manufacturing of robust systems for bulk material handling, especially at power plants and non-ferrous smelters. We have over thirty years of experience with systems specifically designed for hot and abrasive conditions, aiming at low cost of ownership, low operational expenses and high availability. Although Kopar has numerous applications in mechanical conveying, there is an increasing number of pneumatic conveying applications at copper smelters. They relate to conveying of concentrate, and primary and secondary flue dusts. Challenges of pneumatic conveying for concentrate are mechanical and do relate to broad particle size distribution and high abrasivity of the concentrate and the silica. Therefore, special attention shall be paid to system design and ceramically lined bends in the pipeline. Challenges of pneumatic conveying of primary flue dust relate predominantly to material stickiness and poor flowability which are mainly due to fine particle size and formation of sulphates and furthermore, crystalline water. Additional challenges of secondary dust, the white converter dust, are primarily due to the extremely fine 0.1–1.5 µm particle size and problems which come with this. Effect of material characteristics like size distribution, morphology and chemical composition in pneumatic conveying are discussed in detail. INTRODUCTION Fine materials like concentrate, feed mix, flue dusts (from waste heat boiler and electrostatic precipitator) and secondary dusts need to be conveyed at smelters. Both horizontal and vertical conveying and combination of those are used. For the purpose, both mechanical and pneumatic conveying are applied. Most widely used equipment are drag chain conveyors and various combination of pneumatic systems, e.g. air lift, dense-phase and dilute phase pneumatic conveyors. Kopar has 30 years’ experience with multiple material handling systems. Furthermore, acquired companies like Elmomet Oy and SITE Oy (both currently fully merged and integrated into Kopar Oy) have even longer history, especially in pneumatic conveying. It is commonly known that the finer the dust the more difficult it is to be conveyed pneumatically. Sulfates with crystal water makes it all even more difficult, if not ineligible. Challenges related to pneumatic conveying of various fine materials is discussed in detail in the paper.

Jan 1, 2019

By C. Chongo, L. Little, Q. Mclennan

Since commissioning in 2005, First Quantum Minerals’ Kansanshi Mine in Zambia has produced over three million tons of copper and 1.8 million ounces of gold from a deposit with highly varied copper mineralization. The processing plant is complex with three independent flotation circuits, gold gravity concentration, atmospheric and high pressure leaching, solvent extraction, and electro-winning. For the first ten years of operating the plant, copper mineralogy was inferred from total copper and acid soluble copper assays, and various misconceptions developed about the mineralogy which impacted operational strategy and project decisions. In 2015, an on-site mineralogy section was set up with an Automated Scanning Electron Microscope, the Zeiss MinScan. This instrument has provided detailed mineralogical data that have debunked some of the mineralogy myths that had developed, highlighting the key underlying issues affecting processing performance. This has enabled the development of projects targeting losses of specific copper minerals in defined size classes, unlocking significant value. This paper describes some of the early misconceptions around mineralogy at Kansanshi processing plant, outlining projects that have benefitted from understanding copper mineral distribution. Learnings from Kansanshi are to be applied at other FQM sites, with a similar mineralogy program being set up at the Cobre Panama project. INTRODUCTION The deposit Kansanshi Mine is located in the North Western Province of Zambia, and it has been the largest copper producer in Africa for over a decade. The deposit occurs within a broad northwest trending antiform that can be traced for 12 km, hosted in a zone of complicated faulting, abundant vein injection, breccia development and down-dropped rock units that lies within Kansanshi’s mining license. The copper mineralization within the deposit is predominantly vein-hosted, although some is strata-bound, occurring in thin bands and veinlets parallel to foliation, and some is disseminated associated with albite-carbonate alteration (Gray, 2015). Supergene enrichment has led to significant variety in the copper mineral speciation. This alteration is complex, and has not followed the text-book principles with a neat layer of supergene mineralization overlying fresh hypogene ore. Rather, the occurrence and extent of oxidation and supergene enrichment is highly irregular throughout the deposit, sometimes occurring at significant depth in localized pockets and along fault lines. Gold mineralization tends to follow the copper within the deposit, but it is dominated by coarse-grained, free-milling native gold. The extent of copper oxidation – measured as the fraction of total copper that assays as acid soluble – is used to classify ore into three main ore types, named Sulphide, Mixed, and Oxide, which are then fed to three different primary crushers for processing in independent circuits.

Jan 1, 2019

By V. Itkin

"Three methods were tested for the beneficiation of aluminum scrap, generated by heavy medium separation of non-ferrous automobile scrap residue. These were: crushing in a shredder followed by screening; grinding in a ball miff followed by screening; and eddy current separation. The best results were obtained with the grinding-screening method. IntroductionThe usual method of aluminum alloy reclamation from non-ferrous automobile scrap residue consists of a two-step heavy medium separation to remove materials lighter than and heavier than aluminum. The resulting aluminum scrap still contains over 15% impurities such as stones and glass, heavy rubber, insulated copper wire , plastics and heavy metals entrapped by macerated aluminum piece s, composite fragments, etc.(2). Upon melting, these impurities create difficulties and yield a low ingot recovery-65% to 70%, hence small foundries avoid this material.There are a number of ways to improve the quality of aluminum scrap such as:(1 ) crushing of the scrap, which powders the brittle content , a major impurity component, followed by screening out of the dust(2) eddy current separation , which removes metals from the material flow, and(3) implement better methods for density separation.The eddy current separation and two variants of the comminution-screening technique were studied by Intermetco Ltd., Hamilton , Ontario."

Jan 1, 1986

By Jürgen Antrekowitsch, Gerardo R. F. Alvear Flores, Mehmet Ayhan, Christoph Zschiesche

Synergies between copper and lead extractive metallurgical processes enable the processing of a broad range of polymetallic materials. However, this complexity also brings some challenges expressed in terms of complex intermediates and final products. For instance, based on the limited solubility of Cu and Ni in crude lead bullion additional phases will appear during the crystallization of the melt. Beyond the need for continuous optimization of metallurgy the control of phase solidification is a further important pillar to achieve a more efficient process by minimizing the amount and cycles of reverts. This paper describes the microscopy study of one of the most relevant intermediate in the Cu and Pb metallurgy, the Cu based alloy and highlights the importance of applying a well-controlled cooling sequence to improve the overall process efficiency. INTRODUCTION One of the key aspects in Aurubis’s 2025 vision is to move towards the implementation of a multi metal recovery strategy. The implementation of this new multi metal vision is supported by the long tradition of the company, founded in 1866 as Norddeutsche Affinerie, and further developed by adopting modern copper smelting and lead smelting technologies for the processing of primary and secondary materials. The combination of these assets have already build the basis for processing of complex materials in the copper and lead circuits implemented in Aurubis’s facilities. The addition of a new smelting facility, will enhance these capabilities. Aurubis current flowsheet combines Cu, Pb and Zn metallurgy. This includes primary smelting of copper concentrate, processing of secondaries (residues, slimes, slags) and recycling materials (scrap, shredder material, e-scrap). These broad range of materials contain not only the mentioned base metals but also a number of minor metals that requires to be properly managed to ensure efficient recoveries and quality of the targeted metals.

Jan 1, 2019

By J. P. Harrison, K. Gao

It is well known that in situ stress measurements at a given site will generally display significant variability. However, it appears that a robust analysis of such measurements – i.e., one that is faithful to the tensorial nature of the data – is not available. Despite the fact that stress is a tensor, stress magnitude and orientation have long been analyzed separately using classical statistics. In earlier work we demonstrated the applicability of tensor statistics to the analysis of stress variability. Here, we investigate further the difference between tensor and classical statistics with respect to the stress tensor correlation matrix. Our analysis commences with the selection of a series of valid correlation matrices. Then, assuming that standardized tensor components follow the multivariate standard normal distribution, these correlation matrices are used to generate marginal probability distributions of the eigen-parameters (i.e., principal stress magnitude and rotation angle). From these, random stress tensors are generated, their eigenparameters determined, and the probability density distributions of these obtained using both classical and tensor statistics. Our results indicate that, for all correlation matrices, both methods give practically identical distributions for principal stress magnitude. However, the discrepancy between the two methods with regard to probability density distribution of rotation angle is highly dependent on stress component correlation. This discrepancy is usefully quantified in terms of the integral, with respect to orientation, of the difference between the two probability density distributions. This parameter, which we term Area Difference, is closely linked to the magnitude of the correlation matrix determinant, which itself is related to the normal stress correlation coefficient (i.e., ?x ,?y ??). Assuming that Area Difference should not exceed 0.1, we identify the critical determinant for any particular value of normal stress component correlation coefficient. Thus, using published in situ stress data and the obtained critical determinants, we show that for a specific normal stress component coefficient, when the correlation matrix determinant is less than its critical determinant, the more precise tensor statistics should be used to calculate the distribution of rotation angle. These results demonstrate that the customary analysis of stress measurement data may lead to erroneous results, and that tensor statistics appears to be preferred approach.

Jan 1, 2015

By J. I. Jr. Moore

Many articles have been written about the various operations of Britannia mines and mill, as well as treatises on the geology and ore deposits. A partial list of these papers is given below. Most of these papers have covered well the history of Britannia, and have included a thorough discussion of the geology and ore deposits; therefore, in this paper, no account of these subjects. is necessary. However, a short description of the ore deposits will be given as an aid to a clear understanding of the descriptions of the various mining methods. The Ore Deposits The ore deposits at Britannia occur along a shear zone and are five in number, named for the claims in which they lie, as follows: Jane, Bluff, Fairview, Empress, and Victoria. Each of these deposits is called a mine, as they are separated by 500 to 1,000 feet of barren ground. The Jane mine, although the first producer of the Britannia group, has not been in operation for a number of years. The deposit is a silicified replacement in sediments; with very little evidence of shearing. The Bluff deposit is a highly silicified replacement in porphyry, massive and irregular, very hard in the upper 600 feet with practically no shearing, and softer within chlorite schist in its lower 1,000 feet . The Fairview deposit consists of a series of twelve distinct veins or lodes, rather lenticular in shape, and occasionally merging.

Jan 1, 1928

By Andrew Thrift

Overview ? Problem ? Research question ? Literature review ? Methodology ? Results ? Discussion and recommendations ? New developments Problem ? Increasingly higher expectations ? Inadequate consultation leads to conflict rather than collaboration ? Consultation practice is often weak on decision-making ? Influence of consultation on planning is Unclear Research question ? Are Structured Decision Processes (based on decision analysis) an effective methodology for involving stakeholders in consultative decisionmaking in the mining industry?

May 1, 2006