Search Documents

By D. Purdie

"This paper aims to remind researchers, designers, operators, and managers about the benefits of seeding in the design of precipitation stages in their flowsheet. Including a high density solids (HDS™) process encourages the precipitating solids to form on the surface of existing precipitated particles. This paper discusses the application of the HDS technology at Kennecott Smelter, where the authors have witnessed significant improvements in settling and filtration rates. The authors have also applied this technology at various smelter bleed treatment plants worldwide with similar improvements in precipitation and filtration rates. HDS is a registered trademark of De Nora Water Technologies. RÉSUMÉ Cet article a pour objectif de rappeler aux chercheurs, aux concepteurs, aux exploitants et aux administrateurs les avantages de l’ensemencement dans la conception des étapes de précipitation de leur schéma de traitement. L’introduction d’un procédé des boues haute densité (procédé HDS™, de l’anglais high density sludge) encourage la formation de substances solides précipitantes à la surface des particules précipitées existantes. Cet article porte sur l’application de la technologie HDS à la fonderie Kennecott, où les auteurs ont observé des améliorations importantes au niveau de la vitesse de sédimentation et de filtration. Ils ont également appliqué cette technologie à diverses usines de traitement des rejets liquides des fonderies dans le monde entier, et ont constaté des améliorations similaires en termes de vitesse de précipitation et de filtration. Le procédé HDS est une marque de commerce déposée du fabricant De Nora Water Technologies.INTRODUCTION In 1966, the lead author worked as an assistant smelting metallurgist for the Tsumeb Corporation Limited copper and lead smelter in Tsumeb, Namibia. The smelter produced copper and lead, as well as cadmium and arsenic trioxide as byproducts. The cadmium was concentrated in the lead blast furnace off gas dust, and was collected by a baghouse. The baghouse dust was leached with dilute sulfuric acid (H2SO4) in a batch process. The iron and arsenic in the solution were oxidized with potassium permanganate (KMnO4) and basic ferric arsenate (BFAS; Fe(AsO4)x(SO4)y(OH)z·wH2O) was precipitated using milk of lime. The cadmium was cemented from the purified solution using zinc dust."

Jan 1, 2018

By Dharmendr Kumar, Pradip, Beena Rai, Venugopal Tammishetti

"Due to rapid depletion of high grade Indian iron ores, there is a need to utilize low grade fines and slimes. However, these fines and slimes, in their current form, cannot be utilized in steel making due to their high alumina (6-10%) contents. Several beneficiation strategies such as gravity separation, magnetic separation, flotation and selective flocculation are currently being explored for the upgradation of low grade fines and slimes. In our previous work density functional theory simulations were employed to come up with selective flocculants for beneficiation of iron ore slimes. Our simulation results suggested that starch and guar gum are more selective towards iron minerals than other minerals present in the sample. Grinding of iron ore fines becomes necessary in some cases to achieve adequate liberation for removing alumina impurities in Indian iron ores. We have thus investigated effect of grinding of iron ore fines on its selective flocculation-separation.In the present work, we have taken natural iron ore fines from one of the Indian iron ore mines and ground it to -400 mesh (<37 microns) in dry and wet conditions. X-ray diffraction study confirmed the presence of minerals hematite, goethite, gibbsite and kaolinite in the sample. The fine ground samples were used in selective dispersion-flocculation study with corn starch and guar gum flocculants. It is interesting to note that even though the dry and wet ground samples possess almost similar particle size distributions, significant differences were observed in yield and grades of the concentrates thus produced. These differences may be arising due to the coating of alumina containing minerals on iron minerals. We have also studied the effect of addition of dispersant while grinding. Our study suggests that grinding conditions determine the efficiency of the separation process."

Jan 1, 2016

This paper details a brief history of the Australian gold industry from the 1980s gold boom to the present day, highlighting an industry characterised by innovation in plant design and junior companies prepared to "have a go", in contrast to the conservatism of many larger mining companies. Design flexibility, the innovation of new processes, the preparedness to exchange "process know how" and technology singularly differentiated the gold industry from other sectors during the 1980s to the present. The introduction of two stage crushing, semi autogenous (SAG) milling, and pebble crushing, mill innovations, carbon in pulp (CIP) and carbon in leach (CIL) and the North Kalgoorlie screen etc were all exciting changes in the industry.

Jan 1, 2011

By Seungyeol Lee

Currently, a new construction method using a robotic system is widely spreading in construction sites. This study is related to the design of glazing robot?s teach pendant which can improve convenience of handling and hence improve the productivity through the efficient interaction between an operator and a robot while doing glazing works, e.g., curtain wall installing. The suitability of selection and arrangement of control switches was assessed according to mechanical motions of a glazing robot, and design guidelines for improving convenience and productivity were drawn up through questionnaires carried out by site operators. To verify the proposed design guidelines, working time comparison of the proposed teach pendant and the existing teach pendant was executed.

Aug 1, 2013

By K. Prajapati, P. Hes

Transmission of vibration to the operator from percussive vibrating tools is increasingly of concern in industrial and mining applications. Prolonged exposure to high levels of vibration transmitted via the hand causes disorders known as hand-arm vibration syndrome (HAVS). The vascular component of HAVS is called vibration white finger (VWF) and has a debilitating effect on the hand. Vibration at frequencies below 1250 Hz, a tight hand-grip force and cold environments are reported to increase the likelihood of developing VWF. A vibration damping handle design with patents pending that addresses some of the causes of VWF has been developed and retrofits onto jackleg pneumatic rock drills. The handle is decoupled from the drill while maintaining jackleg twist-grip controls on the hand-grip using a combination of sealed self adjusting hydraulic pistons and compliant materials in series, and a new air control valve. The ergonomics of the hand-grip was also modified by the addition of a polyurethane sleeve with a diameter of 50 mm. The new hand-grip reduces direct cold metal contact and minimizes grip force. Measurement of vibration as the quantity acceleration was made in accordance with international standard ISO 5349. Overall vibration damping in all axes of 50% to 63% was attained at frequencies below 1250 Hz. The dimensions of the damping handle are comparable and its weight is only 100 g heavier than a standard handle.

Jan 1, 2001

By Louis Frost

The coal-mining industry of Nova Scotia, particularly of the island of Cape Breton, today faced as no other industry with economic problems calling for progressive engineering with production on an economic basis, must soon enter upon a phase of reorganization wherein all factors conducive to the cost of producing coal relative to the prolongation of the life of the collieries with the ultimate winning of the maximum submarine area must be closely reviewed. Bearing this in mind and applying the process of elimination to coal-mining costs generally, we are left with only three channels through which we may approach the problem of cost reduction in producing coal: (a) intensive mechanization (b) reduction in the cost of labour (c) reduction in the cost of materials. Assuming that mechanization has reached an economic stage and that labour costs have reached an economic limit, we must turn our attention to the general material costs, which may be classified as &apos;live&apos; and &apos;dead&apos; costs. The former take in all things which can be accredited with a fractional depreciation and written off the balance sheet over a period of years. On the other hand, the ?dead&apos;costs-of which the cost of supporting the underground workings form part must be completely written off: for these, no return may be expected, other than the economic return in the reduction of the cost per ton of coal produced.

Jan 1, 1928

By D. Bernard

Over the last decades, the wrought aluminum casting industry has made significant progress with regards to process consistency by the introduction of new technologies in the field of liquid metal processing and casting. These technologies, combined with the application of best practices, have led to increases in productivity as well as better process performances and product quality. The competition in the addedvalue aluminum products (by opposition to P1020 production) is, however, very strong and involves players that did not hold a major role five years ago but who are now exerting a strong competitive pressure on our industry even sometimes from far abroad. There are still technical and technological challenges remaining in the different areas of aluminum casting production, amongst which metal pre-treatment, furnace operations, in-line treatment and casting hold a predominant influence. The comprehension of the contribution of each individual process step to the entire process chain is a key element and must be considered in future process optimisations. This paper presents the technological position of the casting industry and tries to highlight areas where further progress can be made.

Jan 1, 2006

By K. Svens, M. Lahtinen, L. Lehtinen

"Outotec&apos;s direct leaching process is an atmospheric leaching process for sulphidiczinc concentrates. The direct leaching process, based on special leaching reactors developed by Outokumpu and leaching know-how, is the most economical way to produce electrolytic zinc. The newest industrial-scale application of Outotec&apos;s direct leaching process will be started up in 2008 in China at Zhuzhou smelter. The process isintegrated to the existing production plant, replacing part of the old production facilities by modern technology and increasing the production capacity significantly. The process equipment supplied by Outotec includes also tailor-made reactors designed on the basisof the work and experience of Outotec Research Centre."

Jan 1, 2008

By M. Potesser

Higher prices for natural gas or oil have motivated the copper industry to reexamine the modes of oxygen and oxy-fuel burner usage at operating plants. With rising energy costs and the growing importance of environmental protection, burner usage and burner operations have become the focus of several investigations and optimization efforts. One possible approach to lower energy usage is through combustion using tonnage oxygen. When such oxygen is used, the flame temperature increases and operational efficiency is improved. As well, with the correct technology, due to the presence of lower levels of harmful substances such as NOx in the off gas, there is improved environmental performance. As regards copper production, furnaces are employed for both concentrate smelting or for melting and casting operations. The use of tonnage oxygen in concentrate burners for smelting provides for a higher thermal efficiency. For furnaces employed for melting, air-operated burners may in fact have an initial advantage because a long radiant flame is typically generated, thus providing for a higher degree of heat transmission. This paper describes the new experimental burner chamber of Messer Austria GmbH which provides for testing of the combustion of natural gas with oxygen or oxygen-enriched air and the use of special water cooling ducts that simulates a metal charge during melting, The operational effectiveness of the burner is determined from temperature and off-gas analysis data. The paper also discusses future trends in burner technologies including a new patented burner. Cu2007 - Volume III (Book 2) The Carlos Diaz Symposium ou Pyrometallurgy Edited by A.E.M. Warner, C.J. Newman, A. Vahed, D.B. George, P.J. Mackey, A. Warczok Toronto, Canada,

Jan 1, 2007

By H. Miki, S. Wheatley

The addition of precipitated silica greatly enhances chalcopyrite leaching in the presence of sodium chloride at moderate temperatures (65-90°C) in acid media with ferric ions as the oxidant. The beneficial effect increases with the increase in chloride concentration and temperature. The addition of sodium silicate and silica sand has no significant influence. The analysis of solubility data in acid/salt solutions indicates that the solubility of silica as Si(OH)4 as the dissolved species is controlled by the activity of water, as expected from the hydration theory. Kinetic analysis shows the trends that copper dissolution from chalcopyrite in the presence of precipitated silica with sodium chloride follows a shrinking sphere model indicating a chemically controlled surface reaction. The effect of temperature on copper dissolution in the presence of both precipitated silica and sodium chloride was also larger compared to the results in sodium chloride alone. The SEM analysis shows that chloride and silica facilitates the precipitation of sulfur on the surface of the silica particles rather than the chalcopyrite particles which avoids the blockage of the mineral surface and thus improves the leaching kinetics.

Jan 1, 2014

By F. Liu, H. A. Meier, D. M. Valiveti, P. A. Gordon

Hydraulic fracture is a frequently used technique in the Oil and Gas industry to create high permeability pathways for extraction of hydrocarbons. Numerical simulation of this method poses challenges such as representation of 3D fractures, propagation of randomly oriented fractures in 3D media, enabling fluid leak-off from fracture to poro-elastic medium. We have developed a numerical model using the Generalized Finite Element Method (GFEM) to simulate fluid driven fracture in a poro-elastic medium that addresses these challenges. In the GFEM framework, special enrichment functions are used to augment the solution space in the displacement and pore-pressure fields in order to accurately capture the response in the vicinity of the fracture. Adaptive refinement of the finite element mesh is also employed to facilitate accurate and efficient solution of the model. Our model fully couples fluid flow in the fracture, represented with the lubrication approximation, to the geo-mechanical behavior of the bulk poroelastic rock, comprised of an elastic rock skeleton saturated with fluid. Fracturing fluid exerts traction on the fracture surface and is also allowed to leak-off into the poroelastic medium using a transfer function approach. Stress intensity factors (SIFs) are evaluated based on the Contour Integral Method, accounting for the fluid pressure on the fracture surface. The SIFs are used to govern a full 3-D evolution of the fracture. Verification of the model is performed for known behaviors for the poroelastic response and fluid flow in the fracture.

Jan 1, 2015

By Jodi Wilding, Barry Lurnsden

The implementation of new technology to mineral separation operations requires rigorous testing to confirm the technology&apos;s technical and economic benefit. The Jaguar Mine owned by Jabiru Metals is located in Western Australia and sequentially separates a copper concentrate and then a zinc concentrate. Fine grinding (80% of zinc in tail is <25µm) is required to achieve efficient mineral separation. All mineral losses are therefore fine mineral losses, and so improvements in metal recovery must focus on this fine mineral. Magnetic aggregation technology has been shown to increase the recovery of fine paramagnetic minerals so it was an appropriate technology to evaluate at Jaguar. Testwork commenced in the copper circuit and it was found that there was a substantial reduction in copper in copper tail and an increase in zinc recovery to the zinc concentrate. The increase in zinc recovery in the latter zinc circuit was an interesting result and initiated the second stage of testwork that was to install and test a second magnetic conditioning unit in the zinc círcuit. This showed a further increase in zinc recovery. Magnetic conditioning technology has now been fully evaluated in the plant and is now part of the Jaguar flowsheet.

Jan 1, 2011

By P. O. Parfitt

At the McIntyre mine, there are two distinct operations: a gold mine with narrow veins, mined by cut-and-fill methods, and a copper mine with large, open, long-hole stopes. The application of the Critical Path Method to scheduling work in the copper mine, where it has been used successfully for several years, is de-scribed briefly. This application is relatively simple. Use of C.P.M. has now been extended to the gold mine. To replace the former method of scheduling from bar-charts, a procedure was developed for scheduling automatically. To handle an operation of this size and complexity, a computer was essential. Improved schedules are now being produced, with a saving in time.

Jan 1, 1967

By A. Boeing

Rock-breaker automation and remote operation improves the safety and efficiency of mining operations. This article presents an overview of the Rocklogic rock-breaker automation system architecture that provides collision avoidance, automated parking, and remote operation functionality. The system consists of a distributed computer control system that interfaces with sensors attached to the rock-breaker, the rock-breaker hydraulics, and the site infrastructure. We present results of an automated Transmin rockbreaker installed in a production environment at an underground Australian mine site. The system has been in production use for over 900 days during which there have been no reported collisions, and 100% adoption of the remote operation technology. As a result, Rocklogic has significantly improved the safety of rock-breaking operations and reduced the rock-breaking cycle time, thereby improving the sites overall throughput.

Aug 1, 2013

By MAX VOS

Lithium is the lightest and electrochemically most reactive of all metals. Renewed interest in lithium coincides with research in lithium batteries and power generation by atomic fusion. Ontario lithium resources are contained in spodumene pegmatites that can form where medium- to high-grade metamorphic volcanic-sedimentary formations are intruded by pegmatite and porphyritic granitic rocks. Spodumene pegmatites occur in at least twelve locales throughout northern Ontario, all of which are in the Superior Province of the Precambrian Shield. Tantalum, cesium, rubidium, beryllium, niobium and tin also were noted with lithium in spodumene pegmatites. Considerable potential remains for discovery of additional lithium and rare-element pegmatites in northern Ontario.

Jan 1, 1984

By T. Bednarski, T. McCallum, L. Moya, L. Nsenga, B. Mbao

The accumulation of solids in solvent extraction (SX) circuits can cause problems with the physical and economic performance of the operation. These solids are responsible for the formation of crud, a solid stabilized emulsion containing organic, aqueous, air, and fine solid particles. The build-up of crud in SX settlers can limit SX operation throughput, require plant downtime, lead to higher organic losses, or result in higher aqueous in organic entrainment (all of which can have a significant, negative economic impact). Current practices for crud management are typically reactive. Crud is physically removed after it has been allowed to build to excessive levels in the circuit and processed mechanically using centrifuges or filtration. A new proactive solution has been developed to prevent crud formation and build-up. Low ppm dosage of an additive, ACORGA® CR60, into the pregnant leach solution (PLS) has resulted in reduced crud formation in pilot and commercial scale for a variety of PLS streams. This paper will review results from operations in North America and Africa, covering heap leach, concentrate leach, and agitated leach feeds. INTRODUCTION Crud formation and build-up in solvent extraction (SX) circuits has been a long time topic discussed and claimed to be crucial to the whole hydrometallurgical process (Liu, et al, 2006). Crud formation is present in all SX systems be it copper, uranium, zinc, etc., and Ritcey (1980) defined crud as a stabilized emulsion containing organic, aqueous, and fine solid particles. The ore type and feed composition is a major determining factor of crud formation and typically contains Si, Al, Fe, P, and sulfates (Ritcey, 1980). It typically builds at the interface between the organic and aqueous, but can also be observed as floating crud on the surface of the settler, or bottom crud, which is common to find in circuits treating agitated leach feeds such as in Africa. As crud formation has been unavoidable, many of the current crud management techniques are reactive, allowing crud to form and build in SX circuits. Once it does, it is removed and treated via different mechanical techniques, typically through some type of filtration or three-phase centrifuge, to remove the solids and recover the organic phase trapped within the emulsion (Ritcey, 1980). Automated pumping systems have also been designed and are frequently used in North American operations. The time and capital required to react to crud formation can be an overwhelming aspect to SX operation.

Jan 1, 2019

By Minghui Li

China is the largest coal producer in the world. In 2012, the coal production in China is 3.65billion tonnes, accounting for approximately 49% of global coal production. The raw coal production in 2012 was 3.8% more than the year 2011. 56% of total raw coal has been washed. The increase in raw coal production also promotes technology to be developed and brings separation capacity become larger and larger in coal processing in China. At present, over 40 extra-large scale coal preparation plants (each plant has capacity of more than 10 Mtpa) are in operation in China, the largest one is 32.5 Mtpa. Heavy medium separation are widely used in new built coal preparation, the washing limit for thermal coal feed lower and lower, the equipment selection tends larger which brings the whole washing system simplified, the local equipment developed and manufactured are more and more used. By discussing designs of several typical thermal coal preparation plants and coking coal preparation plants in China, this thesis introduces the current design of China?s extra-large coal preparation plants, and sums up the prevailing design features and trends of extra-large coal preparation plants.

Aug 1, 2013

By Michael J. Rosko

Methods have been developed for processing and analyzing reflected solar radiation data obtained by Landsat 5 Thematic Mapper multispectral scanner. Spatial resolution for the Landsat series satellites is 30 meters per side per pixel. Materials on the Earth?s surface absorb or reflect different parts of the electromagnetic spectrum depending on their physical and chemical properties and, therefore, typically have characteristic spectral ?signatures?. Using these signatures, environmental parameters such as surface water and vegetation may be identified and analyzed. Principal advantages of the satellite image method for environmental monitoring include: a relatively long historic period beginning in 1985 for which information is available, the reliable numerical basis for the results, and the ability to assemble a historic environmental baseline and provide on-going monitoring for large or remote areas where standard monitoring methods may not be practical. However, because the long-term continued operation of Landsat 5 is problematic due to the age of the equipment, QuickBird and IKONOS satellite images were processed to determine if the two systems are sufficiently similar in their results to allow continuing monitoring using QuickBird data. The QuickBird satellite was launched in 2001 and collects the same visible and near infrared spectral bandwidths as Landsat 5, allowing for equivalent process algorithms for QuickBird, IKONOS, and Landsat 5 data. Spatial resolution for the QuickBird images is 2.4 meter per side, allowing for more detailed characterization of the land surface; spatial resolution for the IKONOS images is 4 meter per side. Because of several differences between the satellite systems, including degradation of the Landsat 5 sensor, it is necessary to calibrate QuickBird and IKONOS results to the Landsat results to verify similarity. Recent images from the satellite systems have been processed and results have been compared to determine the validity of comparing Landsat 5 and QuickBird/IKONOS images so that these newer data can be used reliably in the future instead of Landsat 5 data. Results from this comparison are presented in this paper and suggest that analyses for vegetation using the two satellite systems are comparable, and that little calibration is required. Results from comparison of surface water results from the two systems are less comparable and is currently being investigated by the authors.

Oct 1, 2009

By Fidelis T. Suorineni

Rapid drifting enables quicker access to orebodies, higher productivity rates and a resultant reduction in activity costs. Increased advance rates, by examination of the key components (face preparation and drilling, hole loading and blasting, scaling, mucking and support installation) in the development cycle, and optimizing these processes is a high priority for research in the Canadian mining industry. Support installation time alone is typically 36 to 46% of the total development cycle time. A reduction in support installation time or techniques and alternative scaling strategies could result in significant gains in drift development advance rates. Support Staging and hydroscaling within the drift cycle could offer alternative drift development sequences that could reduce the overall cycle time. MIRARCO?s research into the support and hydroscaling processes for rapid drift development also suggests that there are many other factors (e.g. mine ventilation services) that have a significant impact on the rate of advance. These factors should be considered to promote and manage safe and rapid drift development. Constraints to the rapid drift development processes can only be overcome by sound construction management practices. In other words, the goals of rapid drifting can be achieved by the implementation of contractor-type construction management. This paper examines various constraints and processes affecting rapid drift development and draws attention to other factors affecting safe rapid drift development.

Apr 1, 2005

By J. R. Parga T., P. J. Valenzuela G., L. S. Quiroz C., P. Guerrero G., J. L. Valenzuela G.

"Pressure oxidation is a hydrometallurgical pre-treatment process used for refractory auriferous sulfide ores. In the work reported here, a refractory pyrite ore sample from the Mulatos mine, Sonora, Mexico was characterized. The sample was subjected to atmospheric cyanidation, and simultaneous pressure oxidation and cyanidation under different conditions of temperature and pressure. The mineral characterization showed that pyrite is the main species in the sample. The gold extraction tests were carried out in an 1-litre Parr pressure vessel at a temperature range of 90-120 °C, a pressure range of 87.5–150 psi (using oxygen), and a cyanide concentration range of 0.8-1.2 %wt. The gold extraction results showed that diffusion through product layer is the rate controlling step.INTRODUCTIONIn hydrometallurgical precious metals extraction, the most commonly used process is sodium cyanide leaching, as shown in the next reactions involving gold and silver (Fleming, 1992; Marsden & House, 2006):4Au(s) + 8CN- (aq) + 2H2O(l) + O2(g) ? 4Au(CN)2 -(aq) + 4OH- (aq) (1)4Ag(s) + 8CN- (aq) + 2H2O(l) + O2(g) ? 4Ag(CN)2 (aq) + 4OH- (aq) (2)“Refractory” auriferous ores or concentrates often contain gold and silver locked inside other sulfide phases such as pyrite. This renders cyanidation ineffective, so oxidative pre-treatments are used in order to convert the sulfide minerals into porous oxide minerals and make cyanidation work more efficiently. Reaction (3) shows the oxidation of pyrite in alkaline media and the formation of the porous oxide (Koslides & Ciminelli, 1992):2FeS2 (s) + 15/2 O2 (g) + 8H- (aq) ? Fe2O3 (s) + 4SO4 2- (aq) +4H2O(l) (3)A process of simultaneous chemical pressure oxidation and cyanide leaching for a flotation concentrate produced in the mine of Bacís, Durango, in Mexico, gave good results (Parga et al., 2007). In the study presented here, it was intended to use this treatment for a refractory pyrite mineral from the Mulatos mine in Sahuaripa, Sonora, Mexico, modifying variables such as pressure, temperature and cyanide concentration to find the best conditions for oxidation and leaching."

Jan 1, 2012