Search Documents

By H Sichani-Teimouri, B N. Noller, J C. Ng, R N. Alsaadi, P L. Breuer, S Shini

Cyanide has been used for over a century worldwide for gold extraction. However, the presence of several metals and metalloids in ore requires greater amount of cyanide for an efficient gold recovery due to their solubilisation in conjunction with gold. The extraction residues are discharged into tailing storage facilities (TSFs) and may cause bird mortality if there is exposure to cyanide-bearing wastewater exceeding the toxic threshold. The toxicity arises from free cyanide released from weak acid dissociable (WAD) cyanide complexes. The International Cyanide Management Code (ICMC) has deemed 50 mg/L of WAD cyanide released into TSFs to be safe for wildlife protection. However, this concentration is based on observations of an apparent lack of toxicity rather than a toxicological approach. The National Industrial Chemicals Notification and Assessment Scheme (NICNAS) identified in 2010 that there is a lack of toxicity data to properly assess the environmental significance of cyanide levels at gold mines. Lack of knowledge for the toxicity of free cyanide and metal cyanide complexes to wildlife led to consider alternative direct assessment techniques for designating safe levels. Whilst toxicity may be assessed by using young chickens with animal ethics approval, the traditional bioassay approach to assess cyanide toxicity is impractical for gold mine TSFs. Bioassays using algal species such as Euglena gracilis, a unicellular alga, are widely used for ecotoxicological studies. A unique feature is that the Euglena gracilis Z cell has plant-like while SMZ cell has animal-like characteristics. The aims of this project are to evaluate the suitability of Euglena gracilis Z and SMZ strains to assess the toxicity of free cyanide and both strong (cobalt) and weak (zinc, copper and nickel) acid dissociable metal-cyanide complexes that may be present in TSFs.CITATION:Noller, B N, Ng, J C, Shini, S, Breuer, P L, Sichani-Teimouri, H and Alsaadi, R N, 2014. Development of a toxicity approach to evaluate free cyanide and metal cyanide complexes in waters associated with gold and other mining, in Proceedings Life-of-Mine 2014 , pp 573–590 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By R-H Yoon

A turbulent flotation model has been developed by considering the subprocesses of collision, attachment, detachment, and froth recovery. AbrahamsonÆs model (1975) of infinite Stokes number is used to model collision, while the attachment and detachment subprocesses are modelled by considering the kinetic energies required to overcome the energy barriers and the work of adhesion, respectively. The energy barriers are determined by considering various surface forces, including electrostatic, dispersion and hydrophobic forces, while the kinetic energies are determined from the particle velocities at close separation distances from air bubbles. The latter has been determined by modifying the turbulent root-mean-square (RMS) velocities of Liepe and Moeckel (1976) and Schubert (1999) in view of a lubrication theory. In calculating the RMS velocities, it is assumed that a flotation cell is subdivided into low and high energy dissipation zones. The model predictions made by varying various hydrodynamic and surface chemistry parameters are consistent with flotation practice.

Jan 1, 2005

By A. Bouchard

"Based on laboratory testwork, a two-stage cleaner / re-cleaner circuit with feed regrind was proposed to replace an existing single-stage middling circuit treating a scavenger concentrate at Inco’s Clarabelle mill. In order to effectively transfer the technology and implement the new flowsheet in the plant, an extensive on-site pilot plant campaign was conducted. After demonstrating the improved metallurgy, the two-stage middlings circuit was successfully implemented at the operation.The present paper describes the on-site pilot plant testwork and the plant metallurgical improvement after implementation of the new middlings circuit. The addition of TETA / Na2S03 greatly enhanced the pentlandite selectivity against pyrrhotite and the two-stage cleaning considerably improved the pentlandite selectivity against rock minerals. The improvement was immediate after the installation of the new middlings circuit. Size by size recovery analysis indicated that a finer regrind would further improve the metallurgy of the new two-stage cleanerhe-cleaner circuit and those modifications are in progress at the mill.INTRODUCTIONThe milling operation at Inco’s Clarabelle mill has been described elsewhere (Kerr and Kipkie, 1985; Agar, 1991). While maximizing the recoveries of chalcopyrite (Cp) and pentlandite (Pn), continuous effort has been directed toward improving pyrrhotite (Po) and rock minerals (Rk) rejection. Inco discovered diethylene triamine (DETA) and triethylene triamine (TETA) (Marticorena, et al., 1994) for pyrrhotite rejection. Falconbridge further improved pyrrhotite rejection using DETA and SO2 (Kelebek, et al., 1995). No special technologies are used in the rejection of rock minerals."

Jan 1, 2001

By Manqiu Xu, Glen Robertson, Steve Wilson, Pete Quinn

"The middlings circuit, once called the pyrrhotite rejection circuit, at Inco’s Clarabelle mill was a single flotation stage. It used to process a combined feed consisting of the main flotation scavenger concentrate and the non-magnetic portion of the magnetics flotation circuit tails. The typical circuit metallurgy was 55% nickel recovery at 6.5% Cu+Ni concentrate grade. In the past few years, a research project with the objective of improving the circuit metallurgy was initiated between Inco’s research laboratory and the Mill’s Process Technology group. This project has gone through three steps: a) initial laboratory studies, b) on-site pilot plant investigation, and finally c) full plant implementation.The present paper describes the initial laboratory test work. The development of a two-stage circuit consisting of separate rock and pyrrhotite rejection stages to replace the simultaneous rejection of both rock and pyrrhotite in a single stage is discussed. A two-stage circuit simulation based on batch laboratory flotation data is also presented. Further development work, including the on-site pilot plant test work and the plant implementation of the new circuit design, will be described in a later publication.INTRODUCTIONThe milling operation at Inco’s Clarabelle mill, Copper Cliff, Ontario processes a rich complex sulfide ore from several large production mines around the Sudbury basin (Agar, 199 1). The sulfide mineralization is simple, consisting of chalcopyrite (Cp), pentlandite (Pn) and pyrrhotite (Po). The main gangue minerals are pyroxene, feldspar and quartz with minor amphibole and talc. Estimates of mineral composition are routinely calculated from Cu, Ni and S assays. In the mineralogical calculations, all gangue minerals are conveniently grouped and treated as rock (Rk)."

Jan 1, 2000

By P. D. R. Maltby

"With the narrow vein structure of Nova Scotia gold deposits, selective mining is rarely possible and mill heads will be too low (below 0.10 oz per ton of gold) to support a conventional mill of up to 1000 ton per day capacity at present gold prices. The recent operation of a small 100 t.p.d. mill at Cochrane Hill using fine grinding - leaching - filtration supported this assertion. Milling costs exceeded $25.00/ton of feed mainly due to high capital, labour and maintenance costs.Accordingly, since 1981, efforts have been directed towards the development of a cheap gold extraction process in terms of both capital and operating costs. The main criteria is to produce gold below US $200 per oz including all administration, mining and process stages. This paper describes such a process development for Cochrane Hill. LOCATION AND HISTORY OF THE PROPERTYThe Cochrane Hill property is located about 8 miles North of Sherbrooke, N.S. on highway No. 7. Sherbrooke is about 180 miles east of Halifax. Gold was originally discovered at Cochrane Hill in the 1860's. Early work consisted of trenching. In the 1930's a small shaft was sunk to about 80 feet and some tonnage treated using a stamp mill with gravity concentration of gold.Northumberland Mines Ltd. acquired a 70% interest in the property in 1977. Subsequent drilling indicated a potential zone of gold mineralization with a drill-indicated tonnage of one million tons having a grade of 0.07 ounces per ton of gold (all high assays cut to 1 oz) down to a depth of 300 feet recoverable by open pit mining methods. In broad terms, the goldbearing zone is about 50 feet wide and 800 feet long and dips at about 70°."

Jan 1, 1984

By Wiebe Boomsma

INTRODUCTION Starting in February 2014, 19 partners from EU industry, research institutions and academia joined forces and formed the Blue Mining consortium. In the following four years, they have set out to work on the development of deep sea mining technology, looking into exploration, identification, economic assessment and vertical transport systems for the mining of seafloor massive sulphides and polymetallic nodules. In the beginning 2018 this research & development project has come to an end. The Blue Mining project was one of the first EU subsidised projects embracing the TRL system. This system describes a method of de-risking technology using a simple 9-step approach. This method requires experimental testing in laboratory and relevant environments to be able to reach the higher levels (TRL>5) This paper will discuss the progress in development of the vertical transport system, with a focus on the performed experimental work. This paper will discuss three topics: • Booster station technology • Riser dynamics • Vertical hydraulic transport process. BOOSTER STATION TECHNOLOGY Deep knowledge of transport processes is a prerequisite for a clog free vertical transport One of the key technologies in the VTS is the booster station. The centrifugal pump booster station concept is developed in Blue Mining, it consists of two centrifugal pumps and multiple valves, assembled in member-type frame. Deep sea conditions pose special requirements on all components due to the extreme pressures at large water depths. In the Blue Mining project a Deep Sea Special Motor has been developed and tested in laboratory and in the field. The motor is completely filled, lubricated and cooled using seawater due to its unique open structure, furthermore it does not require any lubricants minimizing the environmental pressure of the motor. The motor is first extensively tested in a laboratory, after these tests have been concluded successfully, the motor is shipped to Norway where it has been successfully tested for more than 100 hours at 425 meter water depth.

Jan 1, 2018

The Skorpion Zinc Project demonstrated the viability of the production of zinc from non-sulphide (commonly called ?zinc-oxide?) ores, using the leach/solvent extraction/electrowinning process route. The success of Skorpion raised the profile of a number of other zinc oxide deposits, considered to be similar. However, a study of three such deposits demonstrates that the application of whole-ore-leaching may be limited and that the concentration of zinc, or at least the separation from acid-consuming gangue minerals, prior to leaching is essential to the successful recovery of zinc from these deposits. The recovery of zinc is dependent on an understanding of the geology of the deposit, the mineralogical association of zinc minerals with gangue minerals (Boni, 2005) and limitations of mining practice. Flow sheet development and the associated metallurgical test work to derive an economically viable treatment route from two of these deposits are discussed. Key parameters affecting zinc recovery by gravity separation and flotation are presented, demonstrating that even minor differences in mineralogy have a profound impact on zinc recovery and reagent consumption. The study also deals with the determination of appropriate design parameters through metallurgical mapping of the dense media separation process.

Jan 1, 2008

By J. P. D. Strydom

The transmission of excessive vibration to the human body can cause physical stress that may result in crippling pain or permanent disability. Rock drills are known to transmit high levels of vibration that are difficult to attenuate through conventional approaches to vibration isolation. However, it can be shown that once the ISO frequency weighting has been applied, most of the vibratory effect of the rock drill?s motion is concentrated at the drill?s operating frequency. This observation opens the way for utilizing a concept known as vibration absorption, aimed at attenuating the rock drill?s vibration. In essence this entails using the inertia of a secondary vibratory system to counteract the motion of the handle. This article documents an investigation into the use of such an absorber for attenuating rock drill vibration and demonstrates the feasibility of such an approach. A mathematical model of such an absorbing handle was developed and used for design studies. Based on these investigations an experimental prototype model was manufactured and tested. A significant reduction in vibration levels could be achieved.

Jan 1, 2002

By P. L. Dunn, G. T. Adel, E. B. Cruz

Automatic control of fine-coal cleaning circuits has traditionally been limited by a lack of adequate sensors. Although several nuclear-based analyzers are available, none have seen widespread acceptance. In this investigation, image analysis is used for the on-line determination of ash contents in fine-coal slurries. The ash content of a flotation tailings stream is correlated to the mean gray level of the slurry. Based on a 90% prediction interval, an analysis of sensor performance indicates an accuracy of 73[±] 4% ash over a range of from 65% to 90% ash. While the results are comparable, the video-based system costs only a fraction of what a nuclear-based analyzer costs. The sensor is now installed at the Middle Fork preparation plant, which is owned by Pittston Coal Co.

Jan 1, 1999

By P. L. Dunn

Automatic control of fine coal cleaning circuits has traditionally been limited by a lack of sensors. Although several nuclear-based analyzers are available, none have seen widespread acceptance. In this investigation, image analysis is used for on-line determination of ash content in fine coal slurries. The ash content of a flotation tailings stream is correlated to the mean gray level of the slurry. Based on a 90% prediction interval, an analysis of sensor performance indicates an accuracy of 73 ± 4% ash over a range from 65-90% ash. While this result is comparable to existing nuclear-based analyzers, the video-based system is only a fraction of the cost. The sensor is currently installed at the Middle Fork preparation plant owned by Pittston Coal Company.

Jan 1, 1997

By D Asahina, T Endo, H Hosono, T Takemura

Changes in the stress field around faults due to the excavation of underground space or the extraction of underground resources induce fault reactivation. To understand the mechanism of fault reactivation, it is important to observe the deformation and sliding processes of the asperities, which is regionally contacted areas at the fault planes. In the laboratory, triaxial compression tests are commonly conducted to reproduce the stress conditions around faults and study their mechanical behaviours. The conventional measurement devices for triaxial compression testing (eg load cells, local deformation transducers, and piezoelectric sensors) uses sensors to measure changes in the physical properties of rocks, but the direct visual information for the sample condition inside the pressure vessel is limited and can only be estimated from the sample after the experiment. We recently developed a direct visual measurement system to observe the slip behaviour of rocks from the inside of the pressure vessel of a triaxial test apparatus. This paper introduces this visual measurement system and presents some preliminary experimental results. The visual measurement system consists of a steel housing with a built-in commercially available digital camera. The triaxial compression tests were conducted to visually observe the sliding behaviour of the pre-cut specimens and to measure its behaviour through the digital image correlation (DIC) method. The captured images and the DIC results show the displacement field of the specimens for different confining pressure. We verified the sliding behaviour and the failure at/around the triangular asperity under at different confining pressure.

Nov 29, 2022

By G. Girard, A. Larouche, J. Colbert, G. Doyer

"The Direct Chill (DC) casting process uses water to extract heat from molten aluminium and helps to control the solidification process. Many factors such as the water flowrate, water distribution around the mould and water impingement angle have significant impacts on the solidification process. It has been noted that the chemistry variation of the cooling water is also an important factor that has a major impact on the presence of defects on the ingot. A significant change in the water quality can produce defects on the ingots such as cracks, bleedouts, or runouts. Understanding the impact of water quality variation on ingots is therefore essential to ensure good ingot production and reduce defects. This paper aims at describing a new approach to follow the variations of process water quality over time. It is an original and innovative method, which is still under progress. A water quality and stability index (WQSI) is under development to evaluate changes in the water composition based on water physico-chemical parameters. The index is calculated by comparing each of the actual parameters with historical values previously modeled by a statistical law. It is a dimensionless number having an adjustable weight factor for each parameter. The positive or negative contribution of each parameter, with respect to the water cooling capacity, is taken into account to calculate the WQSI. The current selection of parameters is based on knowledge from the literature as well as on empirical experience. When the developed tool will be mature, it could be used to track water variations upon time and anticipate problems, enabling proactive actions to ensure good ingot production.INTRODUCTIONFor many years, the impact of water chemistry on heat transfer, during DC casting, has been of great interest in the aluminum industry. Several papers have been published to demonstrate the correlation between water chemistry and heat transfer (Yu, 1985), (Gildemeister, 2014). Although numerous studies do present the effects of water parameters (i. e. hardness, conductivity, oil, and grease…) on cooling capacity under controlled experimental conditions, they do not reflect the strong interactions between the parameters and variations present in a casting center. Wells and Cockcroft also demonstrated that laboratory based studies are not fully representative of real heat transfer in an industrial casthouse, there are too many factors involved (Wells, Li, & Cockcroft, 2001). In this context, it becomes very difficult to obtain a quantifiable relationship between the capacity of water to cool the ingot and ultimately the performance of the cast."

Jan 1, 2016

By Johnny Lyons-Baral, John Kemeny, Don Kraemer

Ground vibrations from blasting can result in the degradation and failure of rock and soil exposures, as well as damaging neighboring houses and buildings. At the same time, vibration provides an opportunity to regularly monitor the rock and soil exposures. If a geophone or accelerometer is attached to a rock block or wedge on a mine slope, for example, then blast vibrations will regularly “sound” the rock block and the resulting vibrations can be used to assess the stability of the rock mass in the neighborhood of the accelerometer, as well as monitoring the properties of the blast. This paper describes the development of a wireless sensor network based on inexpensive MEMS accelerometers for blast monitoring and rock and soil structural health monitoring. The wireless sensors are placed at various locations in and around an open pit mine or quarry, and transmit data to a central source after ground vibration events occur. As described in the paper, a variety of wireless and non-wireless accelerometers were tested in actual field conditions. This includes the monitoring of over 30 blasts at an open pit mine in Arizona with as many as nine simultaneous accelerometers. Matlab was used to process all the data and develop innovative methods to view and interpret the data. This includes the use of the wavelet transform to determine resonance frequencies, and the use of both ground resonance frequencies and scaled-distance peak particle velocity (ppv) relationships to assess slope stability. As part of this research, a three-dimensional point cloud environment for viewing and analyzing the vibration data from the sensors has also been developed.

Jan 1, 2014

By Bezalel C. Haimson

We have developed a new wireline hydrofracturing technique for in situ stress measurement which eliminates the need for drill rig and drill rod and renders the tripping of the straddle or impression packers continuous, fast, and inexpensive. Wireline conductors facilitate the use of downhole pressure transducers. We have confirmed the suitability of the new technique by testing it in a deep hole near the Monticello Reservoir, South Carolina. Our measurements indicate two local stress fields, one of them apparently linked to the impoundment-related induced seismicity.

Jan 1, 1984

By D R. Rankin, J J. Fuykschot

Forrestania Nickel Mines is owned and operated by Outokumpu Mining Australia Pty Ltd and is situated 400 km east of Perth, WA in the Forrestania Greenstone Belt. Production started in late-1992 at a rate of 600 ktpa and reserves were exhausted in August 1999. Cosmic Boy is the largest of three mines worked and operates in a high stress environment with both very high and very low rock mass strength domains. Stoping commenced in 1995 using conventional benching with long hole slot rises but because of drilling and blasting problems the mine switched to airleg rising. In 1997 the mining method was changed to smaller scale up hole retreat benching with each stope requiring a slot rise of up to 16 m length. This method does not allow top access to the rise location and so airleg rising was used until mid-1998. At this stage mining was approaching areas of higher stress for which it was clear that an alternative to this entry method of rising was required. Small diameter raise boring and Cubex rigs were considered but because of the set up costs were not considered to be viable. Since the ore is relatively soft, burn cuts were developed to make use of specially designed 152, 203 and 254 mm diameter reamer bits (depending on the rise length) and drilled with conventional long hole drilling equipment. These rises are fired in one blast together with the slot rings. In the northern lower section of the mine (below 400 m) the principle stress has been estimated at 60 MPa and this causes minor strain bursting in BIF development headings and loose material to form on walls and backs. Trials of destress blasting modelled on Canadian experience has greatly reduced strain bursting at the face. However only around 300 m of development was affected and so this method had not been optimised when mine development was completed.

Jan 1, 1999

By M. Eraydin

Dewatering fine particles (e.g., flotation concentrates) is inefficient, energy intensive and often requires large capital and operating costs. To address these issues, a series of advanced dewatering technologies have been developed at Virginia Tech. These include novel dewatering aids and a hyperbaric centrifuge. Typically, the moistures obtained using these methods are 30% to 50% lower than those obtained using conventional methods, as demonstrated in laboratory and pilot-scale test programs. With another novel dewatering technology that has been tested in bench-scale tests, the moistures can be reduced to levels once believed to be attainable only through the use of thermal dryers. In this communication, test results obtained with these advanced dewatering technologies are presented and compared.

Jan 1, 2014

By Rong Fan, Andrea Gerson

"The small recovery of Ag, often in the order of 50%, by traditional flotation and leaching process strategies is closely related to the complicated and heterogeneous nature of Ag-bearing minerals with Ag typically being associated with numerous minerals within any given ore-body. Moreover, grain sizes may be extremely fine with micron-scale common. In order to design cost-effective Ag-bearing mineral flotation and leach recovery strategies it is firstly necessary to characterise the speciation of Ag and its correlation with other elements, e.g., Cu, As and Sb, within the ore matrix and process streams. The traditional QEM-SCAN analytical approach can prove problematic for some mineralogies due to difficulties in recognising degrees of crystallinity, polymorphs, complex solid solution series, high value trace element mineralogy, very fine grained materials; and the requirement for a comprehensive data base. Moreover, there is difficulty ‘seeing’ either surface films or surface contaminants which can both lead to poor flotation performance. There is therefore clearly a need to develop confirmatory and complementary approaches when these uncertainties arise. Synchrotron X-ray microprobe analysis provides a powerful tool for the mineralogical characterisation of finely segregated heterogeneous Ag-containing materials. These measurements enable comprehensive characterisation of the Ag-bearing components using synchrotron microprobe X-ray fluorescence mapping (µ-XFM), X-ray diffraction (µ-XRD) and X-ray absorption spectroscopy (µ-XAS). Further analytical strength is provided by principal component analysis of laboratory ToF-SIMS data which enables the statistical identification of correlated surface species enabling examination of surface chemical characteristics responsible for mis-reporting of Ag containing components within flotation streams. We describe the application of these techniques to a selected Ag-containing feed and tail and demonstrate how these compliment and extend traditional analytical methodologies."

Jan 1, 2014

By Technische Universität Braunschweig, K. Saksl, J. Furste, P. Eschenbacher, F. Brunke, D. Wolter, M. Kohnke, C. Siemers, J. Kiese, M. Schlemminger

"In general, titanium alloys combine outstanding mechanical properties with corrosion resistance and biocompatibility and are, therefore, used in many challenging applications. Nevertheless, for special products, well-tailored properties are required which might not be achievable by a specific design so that new or modified alloys are needed. In this overview paper, alloy development strategies performed at the Institute for Materials of the Technische Universitat Braunschweig are discussed at different examples, namely, (1) oxidation-resistant, microstructural-stabilized and cold-workable alloys for exhaust applications, (2) aluminum- and vanadium-free, medium-strength and cold-workable alloys for implants and osteosynthesis applications and (3) free-machining alloys by the addition of particles with low melting points for non-safety critical light-weight constructions to replace heavier steels, e.g. in automotive applications. A special focus is set on the alloy development techniques and the analyses carried out to achieve well-balanced properties by the optimization of the alloy compositions. INTRODUCTIONTitanium belongs to the allotropic metals and can therefore exist in two different equilibrium lattice modifications. Pure titanium crystallizes at 1668°C in a body centered cubic (bcc) structure called ?- titanium which at 882°C transforms to a hexagonal close packed structure (hcp), the a-titanium. A martensitic ?-to-a-transformation is possible at large cooling rates. This thermally induced hexagonal martensite is called the a'-phase. The transformation temperature named ?-transus-temperature (T ?) can be influenced by alloying elements (Peters & Leyens, 2002).For titanium alloy production typical alloying elements are aluminum (Al) and oxygen (O), both a-stabilizers shifting the ?-transus temperature to higher temperatures, whereas tin (Sn) and zirconium (Zr) only show a limited influence on the ?-transus temperature. The ?-stabilizing elements are subdivided into two groups: Niobium (Nb), molybdenum (Mo) and vanadium (V) stabilize the ?-phase between the melting point and room temperature and are therefore called isomorphous -stabilizers. Elements like copper (Cu), iron (Fe) or silicon (Si) also stabilize the ?-phase to lower temperatures but undergo a eutectoid reaction during cooling. ?-titanium then dissociates to a-titanium and an intermetallic compound. Consequently, these elements are called eutectoid ?-stabilizers (Boyer, Welsh & Collings, 1994)."

Jan 1, 2016

By Tony Moore, Peter Riccio

"MMG (Minerals and Metals Group) operates the LXML Sepon’s mineral processing facility located 40 kilometers north of the town of Sepon, in the Savannakhet Province, Lao PDR. The Sepon copper plant produces 70,000 tons/year of LME grade A copper cathode using leachautoclave- SX/EW-flotation technology (Baxter et al., 2003). Pyrite recovery in the flotation circuit is critical to the operation, as it is used to generate acid and soluble ferric ion for the leach circuit. Low pyrite recovery has been an on-going challenge in the flotation circuit. Final tailings characterization work done by Ian Wark Research Institute (Bassell et al., 2006) showed that the pyrite losses to the tailings are made up of a combination of coarse liberated particles and finer particles that have been coated by clay fines.In December of 2005, a joint Cytec-MMG technical program was initiated to address the pyrite recovery issue. A series of diagnostic tests were performed in the Cytec Stamford Research Facility using synthetic plant water showing that the collector was precipitating as a metal salt and was unavailable for mineral attachment. The tests also identified several collector chemistries that would likely be robust in the low pH (< 1), high dissolved metal ion environment and will not complex with metal ions in solution. With the support of the Sepon on-site engineers, an extensive, successful laboratory program was completed, which was subsequently followed by on-plant testing that showed a step wise improvement in pyrite recovery.INTRODUCTIONLow pyrite recovery has been an ongoing problem in the flotation circuit at Sepon. Sulfur recovery (indirect measure of pyrite) was improved from 40% to 65%-75% in mid-2005 when on site laboratory work confirmed that AERO® 8045 Promoter was a more effective collector then AERO® 407 Promoter. However, sulfur recoveries above 65% could never be achieved. Sepon requested the Ian Wark Research Institute to complete a surface analysis study using Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, and Time-of-Flight Secondary Ion Mass Spectroscopy to determine if clay coated pyrite played a role. It was concluded that the pyrite losses to the tailings are made up of a combination of coarse (+ 100µm) liberated particles and finer (-74µm) particles that have been coated by clay fines. The majority of the losses appear to be due to the former. In December of 2005, a series of diagnostic tests were performed in Stamford using synthetic plant water in order to identify what chemistries would likely be robust in the slimy low pH and high dissolved metal ion solution environment. Results showed that several chemistries would not complex with ferric, ferrous or copper in solution and therefore should perform well in the Sepon flotation. The incumbent collector, AERO® 8045 Promoter was complexing with metal ions in solution. This resulted in the collector not being available for adsorption onto pyrite."

Jan 1, 2011

By Peter Riccio

Oxiana Sepon?s mineral processing facility in south central Laos produces copper cathode using leach-autoclave-SX/EW flotation technology. Pyrite recovery in the flotation circuit is critical to the operation, as it is used to generate acid for the leach circuit. However, low pyrite recovery has been an ongoing challenge in the flotation circuit. Tailings characterization work done by Ian Wark Research Institute showed that the pyrite losses to the tail are made up of a combination of coarse liberated particles and finer particles that have been coated by clay fines. In December of 2005, a joint Cytec-Oxiana technical program was initiated to address the pyrite recovery issue. A series of diagnostic tests were performed in the Cytec Stamford Research Facility using synthetic plant water showing that the collector was precipitating as a metal salt, and was un-available for mineral attachment. The tests also identified several collector chemistries that would likely be robust in the Sepon low pH, high dissolved metal ion environment, and will not complex with ferric, ferrous, or copper in solution. With the support of the Sepon on-site engineers, an extensive, successful laboratory program was completed, which then was followed by on plant testing that showed a step wise improvement in pyrite recovery.

Jan 1, 2014