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By L. Kong, V. G. Papangelakis, L. Li

"The Eh-pH diagram of lithium-titanium-water system at 25°C, 100 °C and 200 °C was constructed. It shows that there exist thermodynamic stability areas of Li2TiO3. This indicates a thermodynamic possibility for the formation of Li2TiO3 in aqueous solution. A hydrothermal process has been applied for the preparation of Li2TiO3 using TiCl4 and LiOH•H2O as raw materials. The prepared samples were examined with X-ray diffraction, scanning electron microscopy and thermo-gravimetric analysis and differential scanning calorimetry. The results show that temperature and washing condition have significant effects on the phase composition of the product. Phase-pure Li2TiO3 powders were obtained at 200°C with Li:Ti molar ratio of 2.0.INTRODUCTIONLithium-containing ceramics enriched in 6Li, such as Li2O, LiAlO2, Li4SiO4, Li2ZrO3 and Li2TiO3, are considered as tritium breeding materials (Saito et al., 1998; Roux et al., 1998; Johnson et al., 1998; Hoshino et al., 2002). In view of its admirable properties: low-activation, good thermal stability and thermal conductivity, excellent tritium release performance and reasonable lithium atom density (Kopasz et al., 1994; Roux et al., 1996; Saito et al., 1998; Wu et al., 2008), Li2TiO3 is recognized as one of the most promising candidates of tritium breeding materials. Meanwhile, Li2TiO3, as the precursor of H2TiO3-type lithium absorbent, receives more attention as the development of extracting lithium from salt lakes (Zhong, 2004; Zhang, 2010).Several synthetic techniques have been applied to prepare Li2TiO3 powders, such as solid-state methods (Lulewicz and Roux, 2002; Ramaraghavulu et al., 2011; Mandal et al., 2012), sol-gel processes (Deptula et al., 2002; Lee, 2008) and solution combustion routes (Cruz et al., 2006; Jung et al., 2006; Sinha et al., 2010). A solid-state method may produce a series of problems, including impurity contamination and difficulty in morphology control of the obtained powders, although the process involved is simple. The solgel process is prolonged and usually demands for multi-step reactions, while solution combustion route requires plenty of energy and easily causes product contamination by the fuel used. Owing to its environmentally benign and highly suitable characteristics in fabricating materials, hydrothermal technology has been widely used and became a powerful tool in the field of material synthesis (Yoshimura and Byrappa, 2008). For example, ZnO in the form of bulk single crystals, fine particles and thin films, which is an attractive photoelectric material, was successfully synthesized by hydrothermal process (Sekiguchi et al., 2000; Ohshima et al., 2004). A hydrothermal technique was also used to the preparation of carbon nanotube, which possesses outstanding mechanical, structural and electric properties (Bernholc et al., 1997), and is superior to the commonly used method (Gogotsi and Libera, 2000). There, it provides an option for preparing Li2TiO3. Laumann et al. (Laumann et al., 2010) synthesized cubic a-Li2TiO3 by hydrothermal reaction at 180 °C for 18 h, using TiO2 powder, comprising of anatase and rutile, and lithium hydroxide in de-ionized water. However, the prepared a-Li2TiO3 is extremely unstable with a maximum lithium loss of 75% when treated in bathing experiment."

Jan 1, 2012

By Heidi Fauser

The aim of the project was the development of an electroforming process for the production of medical implants out of gold. To prove the applicability of this technology, tympanostomy tubes were chosen as demonstrators. These barbell-shaped tubes are usually produced mechanically; of silicone or, for higher therapeutic demands, of metal ? gilded silver or gilded stainless steel. Gold electroforming of the tubes as an alternative manufacturing process would reduce the expenditures for the mechanical preparation and lower the corrosion susceptibility significantly. To obtain electroformed gold tubes of the desired shape, the following steps are necessary: fabrication of a negative template by drilling holes with countersinks in an insulated aluminium sheet, electroforming process, removal of the aluminium by using a sodiumhydroxide solution. For the optimisation of the shape and surface quality of the tubes respectively the simplification of the manufacturing process, various parameters were tested, e.g. aluminium quality and sheet thickness, type of insulation layer, substrate processing, hydrodynamic conditions, type of electroforming electrolyte, electrodes position, etc. The manufactured tubes were characterised in view of thickness distribution, hardness, surface roughness and purity in comparison to mechanically produced reference tubes. From the results obtained during the project it can be concluded that electroforming processes can be easily adopted for the manufacture of medical implants. The time-consuming electroforming process is by far compensated by the simultaneous production of an arbitrary number of implants.

Oct 1, 2003

By T. Yalcin

"This paper describes the development of a process flowsheet designed to provide high dewatering rates and to bring about savings in tailing disposal costs. The flowsheet comprises a hydrocyclone, a settling cone and a thickener arranged in closed circuit. The mill tailing, after pulp density adjustment, is fed to the hydrocyclone which yields two products. The underflow product is sent to the settling cone for further dewatering. The overflow product, together with the settling cone overflow, goes to the thickener which, with the aid of flocculants, gives a clear effluent and a relatively dilute underflow. The latter combines with the original mill tailing to form the hydrocyclone feed. Solids finally leave the system in the settling cone underflow which can reach pulp densities of up to 78%, making it suitable for direct disposal or for use as mine backfill.Some discussion is included for the selection and sizing of equipment required for this process. INTRODUCTIONDewatering is an essential process for the disposal of mill tailings which forms an added burden in milling practice, often with little or no return. It is, therefore, desirable to conduct this process as economically as possible. One way of reducing costs would be to increase the rate of dewatering so that savings can be made in the size of dewatering unit s which would lead to lower capital and operating expenditures.A common method of dewatering mill tailings is gravity sedimentation which is frequently carried out with the aid of flocculation. In most cases, flocculation greatly enhances the sedimentation process, but only until a pulp density of 50% to 55% is reached in the settled material.Centrifugal sedimentation in hydrocyclones can provide high pulp densities rapidly, but does not result in a clear effluent.This paper outlines a suitable combination of gravity and centrifugal sedimentations that results in an over-all high rate of dewatering. The system developed produces a material of high pulp density while at the same time giving clear effluent."

Jan 1, 1989

By L. Xia, B. Hart, K. Douglas1, S. C. Chelgani

Development work to optimize a flotation flowsheet for rare earth element (REE) recovery is underway. The original approach used alkyl phosphates and phosphoric acid ester as collectors to concentrate REE minerals. To improve REE recovery, hydroxamates as alternative collectors were investigated. In this paper, micro flotation of REE minerals using salicylic, benzoyl and naphthoyl hydroxamates is reported. Unlike phosphonic collectors, slime removal does not show a significant effect on REE recovery when using hydroxamates as collectors. Among the three hydoxamates, the grade of La, Ce, and Nd for concentrates produced by salicylic hydroxamate is the highest. The recovery response with naphthoyl hydroxamate is similar to that of salicylic hydroxamate; good grades for La, Ce, and Nd, less effective for Nb, Y, and Zr. The data indicated an affinity by salicylic and naphthoyl hydroxamtes for LREE over the HREE minerals. In comparison, benzoyl hydroxamate indicated an affinity for Nb, Y, and Zr. Temperature effects on REE recovery were also studied. The grade and recovery of REEs generated by flotation using a mix of salicylic and benzoyl hydroxamates at room temperature was almost identical or even better relative to the recovery using naphthoyl hydroxamates at elevated temperature.

Jan 1, 2014

By Rae Simpson

"This paper provides insight into the elements of computerized maintenance systems and identifies some of the factors which influence their effectiveness. The paper describes what to expect in terms of benefits and problems, the nature of effective computerized maintenance systems, some of the systems available and a process for selecting a system for your organization.The paper will be of interest to mining company executives and maintenance or computer personnel who are involved with, or contemplating, the introduction of computerized maintenance systems.IntroductionIn the drive to improve profits in an increasingly competitive world, mining companies are now using some of the most sophisticated equipment available. The introduction of large and complex equipment such as drag lines, haul trucks, and high-capacity milling equipment has resulted in order-of magnitude improvements in productivity. However, this productivity is now, more than ever, dependent on the continued operation of the equipment. A prolonged breakdown of a critical component can have a significant effect on companies' bottom-line results. As more technologically sophisticated equipment is introduced, maintenance costs become an increasingly important factor for mining companies.Fortunately, sound modern management principles are being used more often in maintenance departments. Progressive maintenance managers are turning to computers to help manage the myriad of details associated with running a maintenance organization.Some maintenance departments in larger mining operations would find it difficult, if not impossible, to operate at current productivity levels without their computer systems. Unfortunately, some other companies gain very little from their computerized systems and would probably be better off without them.How can you be sure that computerized maintenance will improve the maintenance picture for your company? What benefits can you expect to achieve? How do you go about selecting a maintenance system for your organization? These are some of the questions facing industry managers and executives today. In the following sections, we will provide some guidelines and insights to help address these challenges."

Jan 1, 1988

By A. Mellek, M. Pischtschan, M. Perrucci

ABB has received an order for one of the most challenging mill drive projects in its history. With one SAG mill and one ball mill to be added at an iron ore mine in Sweden, the customer’s plant managers wanted to have the most efficient solution for driving their mills but had the budget limitations typically faced by the majority of mining companies during periods of market downturn. To find the best balance between cost of acquisition and highest performance throughout the lifetime of the plant, ABB was selected to deploy a synchronized bypass solution, in which only one drive system is used for two different mills in series. However, being one of the first grinding mills in the world with such a solution was not the only challenge the ABB team faced: The inclusion of some mill application functions - e.g., frozen charge protection, automatic positioning and creeping mode - brought the demands on the engineers to another level. With only one frequency converter and one mill application controller available, the configuration logic and interlocks had to be meticulously designed and thoroughly tested to ensure a smooth and safe startup. The solution offers a footprint reduction and more operator flexibility at a reduced investment as each mill can be run in both directions, and wear on the mechanical components can be greatly reduced due to ABB’s premium ring-geared mill drive (RMD). This paper will describe the details of the project, the configuration developed and the tests performed to guarantee correct software functionality. Mill startup is scheduled for January 2016.

Jan 1, 2016

By W. de Klerk, M. B. Thorpe

Golden Star Resources Bogoso operates in Ghana’s Western Region. The gold recovery plant includes; a flotation circuit producing a concentrate for the BIOX® process that oxidizes sulphides before a CIL circuit; and a dedicated CIL circuit. BIOX® uses bacteria, therefore water from the BIOX® and CIL plants remained separated; CN water could not be introduced into the flotation / BIOX® circuit. The operation built a process water inventory with high TDS and installed a process water treatment plant (PWTP). Water was released in compliance the permits but containing some thiocyanate. The PWTP brine was returned to the TSF, further exacerbating the TDS. The operation experienced a drought removing the traditional water sources; the team evaluated the options to maintain production - various water streams were laboratory tested provided options for water use. The paper presents the story (treatment chemistry and process chemistry) of continued operations by treating stored water and PWTP discharge water with peroxide; brine usage within the CIL circuit, which increased gold recovery (laboratory testing) and reduced the TDS. Water flows were further modified to include hydraulic tailings re-mining to a CIL circuits. Details of the recovery, basic chemistry and costs savings are provided.

Jan 1, 2014

By Daniel L. Cluff

The Canadian mining industry needs to find viable alternatives to the conventional cemented pastefill/hydraulic methods of backfilling open stopes for underground mines located within a permafrost zone. The harsh environment and the isolated location of a mine north of 60° impose additional challenges to standard backfill methods and opportunities to the technological and operational issues related to the use of frozen fill. Underground open stoping mining methods require the placement of fill material to enable the controlled recovery of ore from secondary and tertiary stopes. The typical design of the fill material requires the specification of inert material, water and binder. The permafrost conditions provide the additional parameter of subzero temperatures for backfill design and process control. The paper presents the results of an experimental field study, using large size samples, to determine the strength capacity of frozen backfill. The experimental work was performed utilizing rockfill and tailings material with moisture content consisting of water and ice crystals. Preliminary results indicate that the mixture of rockfill, tailings and moisture, develops strength that meet the demanded requirements for open stoping. A thermal equilibrium modelling analysis is presented in the paper.

May 1, 2008

By H. W. King

"Cryogenic engineering is concerned with components and machines which operate for long periods of time at temperatures within a few degrees of absolute zero. The absence of a ductile-brittle transition is thus the prime component of the specification for a suitable low-temperature alloy. The word "" cryo"" means ""frost-forming"" , and this leads to the second component of the alloy specification, which is resistance to corrosion in humid atmospheres. Further, although most early applications of low-temperature alloys were limited to the storage or transportation of liquified gases, an increasing proportion of alternative energy storage and conversion technologies are being based on the availability of high-field superconducting solenoids. The third basic component of the specification for a low-temperature alloy is thus the absence of a low-temperature ferromagnetic transition.Although the firs t two of these components of the specification can be met by using austenitic stainless steels, many of these supposedly "" non-magnetic"" alloys have been found to undergo martensitic transformations to ferromagnetic phases at very low temperatures. In addition, steels which remain structurally stable may still exhibit other magnetic transitions, e.g. to antiferromagnetic or superparamagnetic states. The successful application of these alloys in cryogenic engineering has thus required an initial basic study of the types of magnetic transition that can occur in such concentrated solid solutions, followed by a more applied study directed at an alloy formulation which will induce beneficial magnetic states at low temperatures."

Jan 1, 1981

By A. V. Corlett

MR. C. S. Gibson: Mr. Chairman, I listened with much interest to Mr. Corlett's paper. Those of us who are directly engaged in mine ventilation and dust control are impressed by the improved atmospheric conditions to be derived from the use of methods of mining such as those in operation at Aldermac, which Mr. Corlett has just described, and those employed at Noranda. It is a well known fact that drilling-dust is one of the most potent factors in the production of silicosis in mines handling ores containing quartz, so that from that angle the use of diamond drills, instead of percussion drills, to drill ore for blasts in stopes is an important development. A second point which I think merits mention is blasting. Blasting, we all know, creates the most dust in a mine and the fact that you can drill ore for a large blast with diamond drills and fire it, say, on Saturday night, and then have all the next day to ventilate the workings, is a great advance in dust control. 1 have wondered if Mr. Corlett, or possibly those at Noranda, can en-vision the use of the diamond drill as a means of advancing cross-cuts and drifts, preparing stopes, etc. I believe it is a matter which is receiving considerable attention at the moment in some parts of the world and J thought it would be interesting to have Mr. Corlett's reaction on that point. MR. A. V. CORLETT: I am not quite so hopeful of using diamond drills as a means of drilling holes in the ordinary drift. Maybe some of the diamond drill men can give us some further information on that point. MR. R. D. LoNGYEAR: The diamond drill manufacturers are working on that problem, but until further work is done we have nothing definite to offer. Drilling holes with a diamond drill to compete with rock drills for advancing drifts and cross-cuts is a desirable objective, because of the elimination of drilling dust and the ability to cut a smooth bore of uniform diameter. To reach this objective, higher rates of penetration are required, which can only be achieved by discovering the optimum bit rotating speed, by reducing vibration, and by further improving the bits and machines. We are optimistic, but the problem is still largely in the research stage.

Jan 1, 1940

By M. G. Mena, M. S. Mena-Junio

Silver (Ag) filler is the most attractive choice among all the conductive fillers of die attach materials for the attachment of silicon devices because of its balanced properties and relatively low cost. However, a major problem of silver is that it electrochemically migrates in the presence of moisture and applied bias. In microelectronic devices, silver migration can occur between adjacent conductors/electrodes, which leads to the formation of dendrites and eventually results in short-circuit failure. In order to assess the reliability of these conductive fillers, an investigation for two types of Agfilled die attach materials was done using the water drop test at room temperature and using a 1000 hour temperature-humidity-bias (THB) test under 85 ºC and 85% RH conditions. Four different bias/voltages and six different electrode distance spacing were used. Both dendrite and cloud/lace-like growths were observed as a result of the electrochemical migration of silver, Water drop test results revealed that increasing the applied bias/voltage and decreasing electrode spacing causes migration to occur faster, thus resulting into shorter time to fail (TTF). It was also observed that the growth rate of the dendrites from the cathode increased linearly as the dendrite approached the anode, probably due to a combination of increased ion availability and electric field. A minimum applied bias of 3 volts was required for migration to occur in Epoxy A as compared to 2 volts for Epoxy C. The higher migration voltage requirement for Epoxy A was attributed to the higher volume resistivity of the said epoxy. In addition to the minimum voltage requirement, it was observed that a minimum electric field of about 1 volt/mm is required for migration to occur. The 1000 hour THB testing did not result into any failures. It is surmised that the presence of condensed moisture is another requirement for migration. Such condition is not present during the THB testing.

Jan 1, 2012

By G. Dubé, A. Leclerc, P. Quinn, G. E. Agar, J. Y. Clouthiér, J. D. McLaughlin

"Gold dissolution by cyanide requires the presence of oxygen which is usually supplied by sparging compressed air into the gold containing slurry. For those ores that contain certain obnoxious substances that consume oxygen, maintaining the required minimum level of dissolved oxygen can be troublesome. One of the most economical solutions to the problem of low dissolved oxygen, especially in plants that have air compressors installed, is to enhance the rate of oxygen mass transfer.The oxygen mass transfer rate was measured in a two phase system using two different sparger arrangements, and with addition of a frother that is known to reduce the bubble size produced by the sparger. The common sparger system was shown to be inefficient compared to a readily available but under utilized method of gas dispersion which introduces air directly below the reactor turbine. Transfer of this technology to an operating plant confirmed the beneficial effect of the improved sparger system. The addition of the frother did decrease the bubble size, but it also reduced the oxygen mass transfer rate."

Jan 1, 1993

By W. D. Gould, A. Kapoor

Acid mine drainage (AMD) is characterized by low pH and high concentrations of sulfate and dissolved metals such as iron, manganese, aluminum, zinc, and copper. Chemical treatment of AMD achieves pH neutralization and toxic metal removal but also produces large quantities of bulky sludge that requires long-term storage facilities and monitoring. Chemical treatment of AMD achieves only partial removal of sulfate (SO4) and total dissolved solids. Sulfate reducing bacteria (SRB) have been used for the removal of sulfate from industrial process wastewaters. The biological sulfate reduction process generates sulfide and alkalinity. The sulfide produced in the biological sulfate reduction process is used to precipitate metals present in AMD as their respective sulfides and the alkalinity generated is used to neutralize the AMD. This review article will present an overview of biological sulfate reduction processes using SRB, bioreactor configurations, AMD treatment studies, and full-scale systems in operation for the treatment of acid mine drainage.

Jan 1, 2004

By I. Farr, P. Quinn, H. Mani

"Difficulties in the flotation of Inca's ultramafic ores at the Thompson Mill are related to the presence of serpentine slimes and some floatable rock minerals. Serpentine slime coatings depress pentlandite recovery while rock flotation decreases concentrate grade. Carboxy methyl cellulose (CMG) has been shown to promote sulphide flotation and to reject floatable rock.To improve ultramafic ore flotation, CMC addition in the rougher stage was studied in a laboratory scale column. Batch tests were conducted in the lab and followed up with continuous testwork at the Thompson mill. At 0.5-1.0 g CMG per kg ore, pentlandite recovery is increased by 5-10% in rougher flotation, pentlandite/rock selectivity is improved and pentlandite/pyrrhotite selectivity is unaffected.IntroductionAt Inca's Manitoba Division, two distinctly different sulphide ores are processed at the Thompson Mill, primarily by froth flotation. The sulfide ores are contained within the Thompson Nickel Belt and currently there are two operating mines, Thompson and Birchtree. Sulphide mineralization in both mines is simple, consisting of pyrrhotite (both monoclinic and hexagonal), pentlandite, and minor chalcopyrite. Both deposits are hosted by metasedimentary and metavolcanic rocks with variable ultramafic rock associations. Ultramafic rocks are mostly serpentinites: magnesium rich rocks composed predominately of serpentine. There is little serpentinite at the Thompson mine, while mineralization at Birchtree is closely associated with significant ultramafic rocks.Excellent recoveries of pentlandite (Pn) and chalcopyrite (Cp) are achieved at the Thompson Mill when processing ore from the Thompson mine. In treating the ultramafic associated Birchtree ore, nickel recoveries are some 6 to 8% below that achieved with Thompson ore. Furthermore, a typical concentrate from Birchtree ore contains more rock and is higher in MgO content. The presence of rock in the concentrate is related to free floatable rock species as well as rock locked with sulfides. The reason for the difference in flotation responses of these two ores has been the subject of on-going re-search."

Jan 1, 1998

By D. Embury

The construction and utilization of oil and gas pipelines is a vital aspect of the Canadian economy. The evolution of materials for this application can be considered as part of an evolutionary process in which the processing of the materials is linked to the design requirements of the pipeline. The evolution of both materials and designs will be considered in terms of parameters such as yield strength, work hardening characteristics including strain path changes such as the Bauschinger Effect and toughness. The final portion of the presentation will consider the possible uses of non-metallic materials, composites and 'smart 'systems in pipeline construction.

Jan 1, 2005

By M. Spreij, M. Hogenboom

Refractory lining performance of aluminium melting and holding furnaces and downtime due to refractory re-linings, are important parameters for increasing the aluminium output of a cast house and decreasing costs. The importance of refractory materials testing is illustrated by examples of improvements made in refractory lining concepts, quality control and introduction of alternative and newly developed materials. These examples also show that the information given by product definitions of refractory suppliers will in many cases be insufficient to judge the risks and benefits of using alternative materials.

Jan 1, 2004

By Jorge M. C. Soares

The CO oxidation reaction has been studied on Au/TiO2 catalysts prepared by incipient wetness (IW) and deposition-precipitation (DP) methods. Additionally the assessment of activity was also conducted on simple gold compounds (Au2O3 and Au(OH)3) and their physical mixtures with TiO2. We have found that there are three types of CO2 production from fresh catalysts, which are only dried, namely: Non-catalytic Type I (low temperature CO2 production); Non-catalytic Type II (higher temperature CO2 production) and Catalytic Type III. The DP catalysts are far more active for Type III reaction, showing activity already at room temperature, whereas the IW catalysts generally do not show steady state conversion until T>673 K. This is due to both large particle size and the presence of residual chlorine for the latter. No truly catalytic activity was found for low temperature CO oxidation on gold precursors on their own, although both Au2O3 and Au(OH)3 react well with CO even at room temperature in an irreversible manner (Type I reaction). Despite that, catalytic activity was obtained by mixing Au(OH)3 or Au2O3 with TiO2 which gives further emphasis on the importance of a good contact gold/support and the absence of chlorine.

Oct 1, 2003

By Todd Smith

AGENDA Newalta overview Dewatering underground slimes: current technique & challenges Why centrifugation? Process improvements & advantages How centrifuge technology works Implementation: first step Summary of benefits

May 1, 2013

By A. Bezama

For over a decade European countries have addressed contaminated sites by developing technologies for managing both polluted soil and groundwater. This development has not only been driven by health and environmental aspects, but also because of economic pressures, as the remediation and redevelopment of derelict areas can be a meaningful alternative to undeveloped areas for the establishment of new industrial, recreational, housing and service locations. In most developing countries, however, the subject of contaminated sites is a new environmental issue that authorities have recently started to deal with. Among these countries, Chile has just started to prepare the country's legal context as well as to foster the formation of research and investigation groups that will deal with the exploration, investigation and management of contaminated sites. That requires a comprehensive technical, scientific and legal support in this stage. Goal of this article is to present the state-of-the-art technologies for site remediation currently applied in industrialized countries, in order to identify the most interesting approaches that can be implemented within the Chilean situation, especially considering the influence of the copper mining industry on the soil and groundwater quality of the environment surrounding their production facilities.

Jan 1, 2007

By Roger Moss

OUTLINE Area selection Mineralization/Alteration Styles Island Copper Mineralization Geophysics Geochemistry Coppercorp Setting Mineralization Geophysics Geochemistry Formation Common Characteristics Conclusions

Apr 1, 2005