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By Gerardo Fuentes

Arsenic extraction from Chilean copper concentrates up to nearly 99% was achieved, using hydrothermal reactions. Arsenic appears in nature in more than 200 mineral species, being arsenopyrite (FeAsS), enargite (Cu3AsS4), and tennantite (Cu12As4S13) the most common species. In addition, arsenic is present in a large amount of copper concentrates, produced in northern Chile. Medical statistics show that in northern Chile, the amount of cancer to the lung, skin and bladder are the highest in the country. The latter situation, demonstrates the importance of studying metallurgical processes that do not generate atmospheric pollution. The hydrometallurgical processes such as hydrothermal treatment in autoclave reactors, do not produce gaseous emissions. On the other hand, the arsenic remains in solution from where it can be transformed in scorodite by widely known methods. Previous works about hydrothermal treatment of enargite have shown the feasibility of transforming the enargite of the copper concentrates into chalcocite or mineral species of the chalcocite family such as djurleite, digenite and for this reason enrich the concentrate in copper and pass the arsenic to solution. For this research, two Chilean copper concentrates were used, concentrate 1 with 5.5% arsenic and concentrate 3 with 1.8% arsenic. These concentrates were subjected to a complete chemical and mineralogical characterization. Later these concentrates were carry out to batch tests of hydrothermal treatment. Also, these concentrates were subjected to grinding to have different particle sizes. For the hydrothermal tests, a liter capacity Autoclave Engineer reactor was used. Characteristic of this reactor was the maximum temperature 350°C, 5000 PSI pressure, and 900 rpm agitation speed. Kinetic tests were carried out with the two concentrates maintaining the same solid: liquid relationship, the same agitation velocity and the variables studied were treatment temperature, time of reaction, concentration of copper in the solution and grain size of the concentrates. The conclusions of the study indicated arsenic extraction of the order of 93.98% from the concentrate 1 and arsenic extraction of the order of 98.74% from concentrate 3. After the hydrothermal treatment, the solids and solutions were characterized chemically, by electron microscopy and X ray diffraction. Also the solids were characterized by grainsize through a particle size analyzer (MICROTRAC). Results of batch treatment shows that arsenic can be release almost completely from real copper concentrates using this hydrothermal process and the next stage will be a scale up process in order obtain results for pilot plant design. INTRODUCTION Arsenic is an impurity that appears associated with copper minerals forming enargite, tennantite, tetrahedrite, and that due to the pyrometallurgical treatment either in conversion or roasting furnaces, it goes into the atmosphere together with the sulfur dioxide. A great quantity of literature can be found to eliminate arsenic or try to separate arsenic from copper. The methods used are mainly leaching processes with or without pressure (Padilla, Jerez & Ruiz, 2015) with different reagents like chloride media (Herreros, Fuentes, Quiroz & Viñals, 2003) or chloride media with sulphuric acid (Riveros & Dutrizac, 2008) or sodium hypochlorite (Mihajlovic, Strbac, Zivkovic, Kovacevic & Stehernik, 2007). It is known too that Chile is the first copper producer in the world and a great quantity of its minerals are in the north of the country, in Antofagasta.

Jan 1, 2019

By A. Hosseini

Full-scale rupture tests were conducted on 508 mm (20 in) diameter API X-60 5.7 mm wall thickness pipes containing either axial semi-elliptical cracks or simulated corrosion defects with equivalent depths ranging from 20 to 60 percent thickness. In the case of the cracks, the failure pressures were predicted with reasonable accuracy when considering a level 3 failure assessment diagram (FAD) procedure based on API 579, as compared to level 2 FAD, since the mechanical properties were known. In both cases, the accuracy improved for shallower cracks. Considering simulated corrosion defects, the RSTRENG approach provided more reliable results on predicting the collapse pressure. For a similar depth and profile, the cracked pipes failed at a lower pressure than those containing simulated corrosion defects of equivalent depth.

Jan 1, 2010

Slurry flow, including flow through the charge, through the discharge grates, along the pulp lifters and its discharge from the mill is an important contributor to the efficiency of the grinding process within a SAG mill. Poor transport of finer ground material can adversely affect grinding leading to excess energy consumption and over-grinding of fine material. This paper extends a 1-way coupled DEM-SPH method to three dimensions and applies it to a 1.8 m diameter by 0.6 m long AG/SAG pilot mill. This provides detailed information on the internal flow of slurry within a SAG mill, including the prediction of dry regions and of slurry pooling. Full 3D analysis also allows the pulp flow patterns into and out of the mill via pulp lifter chamber to be investigated.

Jan 1, 2012

By S. Malkin, Z. Shi, H. Attia, D. Chellan

An experimental investigation is reported on creep-feed grinding of a nickelbased alloy (IN718) using conventional aluminum oxide grinding wheels. Straight surface grinding expe.riments were conducted on nickel-based alloy blocks over a wide range of grinding conditions with straight oil as- grinding fluid applied at high pressure. Grinding power, forces, workpiece surface roughness, and radial wheel wear were measured. Specific material removal rate as high as 64 mm2/s was Used without burning the workpiece, which can be attributed to the extremely low specific energy of 12.6 J/mm3. It was found that the grinding wheel under the present test conditions had a strong capability of self-sharpening as indicated by the stabilized power, forces, and surface roughness after an initial short transient.

Jan 1, 2006

By A. E. Reschke

Optimized mine planning of the Leeville Gold Mine, Nevada, necessitated the requirement for an average of 2540 tpd of high quality cemented rockfill (CRF) in primary stoping blocks and underhand cut and fill workings. To meet this requirement, a number of innovative design features were incorporated into the overall batching plant design. Foremost is the use of a dedicated skip to transfer crushed aggregate from surface down through the ventilation shaft to twin underground storage silos. Also, the use of a high shear colloidal mixer on surface to pre-slurry a cement/flyash binder with pipeline delivery to one of two separate underground CRF mixing stations was incorporated. Finally, the binder and aggregate are combined in a 9 m3 twin shaft compulsory type mixer before loading into teleram trucks for placement.

May 1, 2007

By M. Solomon

Giant, sediment-hosted lead-zinc deposits in northern Australia fonned during development of Mid-Proterozoic extensional basins that overlie Lower Proterozoic basement. The basement in the Mount Isa area, exposed by folding and faulting, contains fractionated, high-heat-producing granites. These granites generate heat at a rate of about 6",Wm-3, probably sufficient to fonn giant lead-zinc deposits either by (a) driving episodic convection of saline basement and basin fluids for periods of IOS to 106 years at temperatures of about 230°C, or (b) heating basin fluids moving under the influence of topographic relief or fault movement. The presence or absence of such granites may form a vital component of the genetic model. Ore-fonning fluid flow was probably initiated by continent-scale, extensional basin fracturing.

Jan 1, 1992

By M. Solomon

Abstract -Giant, sediment-hosted lead-zinc deposits in northern Australia formed during development of Mid-Proterozoic extensional basins that overlie Lower Proterozoic basement. The basement in the Mount Isa area, exposed by folding and faulting, contains fractionated, high-heat-producing granites. These granites generate heat at a rate of about 6 ?Wm-3, probably sufficient to form giant lead-zinc deposits either by (a) driving episodic convection of saline basement and basin fluids for periods of 105 to 106 years at temperatures of about 230°C, or (b) heating basin fluids moving under the influence of topographic relief or fault movement. The presence or absence of such granites may form a vital component of the genetic model. Ore-forming fluid flow was probably initiated by continent-scale, extensional basin fracturing.

Jan 1, 1992

By G. Plascencia, A. Warczok, M. Zamalloa, T. Utigard, N. Behnood

The objective of this investigation was to investigate interactions between high-grade copper mattes and Rexal 60DB direct bonded basic bricks. The infiltration and attack of Rexal 60DB bricks by copper matte and continuous converter matte was investigated in laboratory tests at temperatures up to 1300 °C. The brick dissolution and infiltration tests did not show any significant difference between the 70% Cu and the 81% Cu mattes. More metallic copper was visible in the pores in the case of 81% Cu matte. An important mechanism for direct-bonded magnesia-chrome brick destruction is that oxysulphides start to infiltrate the brick, followed by slow oxidation of the matte producing metallic copper and cuprous oxide, which then react with MgO and Cr2O3, primarily attacking the direct bonds of the brick.

Jan 1, 2004

By C. Robinson

The Diavik Diamond Mine is located in one of the most remote and forbidding places in the world, 220 kilometres south of the Arctic Circle and on the bed of a vast northern lake, Lac de Gras. A single road, built out of ice and crossing frozen lakes, connects the mine with other operations and Yellowknife, the capital of the Canada's Northwest Territories. Diamonds were first discovered in the Lac de Gras region in the early 1990s, and construction of the Diavik Diamond Mine was completed in 2003. Diavik currently mines three kimberlite pipes. Open pit mining has now concluded and all three pipes are mined using underground mining methods. In early 2010, Diavik began mining and processing initial ore from its new underground mine; underground mining operations are expected to continue beyond 2020. The initial mine ventilation system was an exhausting (pull) system with fresh air supplied by a fresh air raise and a main ramp. Return air was exhausted via two raises and a secondary ramp. The system had a total flow capacity approximating 401-411 m3/s. With planned increased production and with changes in mining method, it has been proposed to change the mine ventilation system to a positive (forcing) ventilation system in order to meet projected increases in flow requirements of 566-708 m3/s. Extensive engineering work was developed in order to successfully achieve the changes in system configuration. In the proposed configuration, the main ramp is in an exhaust configuration and exhaust raises are converted to fresh air raise. A number of system implementation options were investigated and phased plans for system execution have been developed. The proposed changes to the ventilation system are substantial and involve extensive construction work. Work was commenced in 2011, each planned phase has been successfully completed to date, and system changes continue today in order to achieve complete system flow reversal and increased flow distribution. This paper details the design of the modified ventilation system and commissioning work which will allow the mine to meet its future production targets.

Aug 1, 2013

By Tong Qin, Jinxia Zhang, Fusheng Niu, Limei Bai

"The interaction between a deformable bubble and a rigid particle in viscous liquids under microgravity conditions is studied by direct numerical simulation via an Arbitrary-Lagrangian-Eulerian (ALE) method. Due to the microgravity, the bubble will stay as a sphere in the fluid without external forces and its deformation is caused by the moving particle. In this study we assume the flow field is axisymmetric and the motion of the gas inside the bubble is neglected. The particle equations and the Navier-Stokes equations for the fluid are solved in a unified finite element framework. The particle obtains an impact velocity by an external force and the impact velocity is varied over a wide range. A ‘critical time scale’ T0 was identified for the interaction process. For successful contacts between particle and bubble, the time scale of their relative motion must be less than T0.INTRODUCTIONThe particle-bubble interaction is an important process in many applied industrial domains such as water treatment, froth flotation and liquid steel purification. It is a complex three phase process in that it embraces many research areas: fluid hydrodynamics, interfacial forces, particle and bubble behaviour and solution chemistry.Derjaguin and Dukhin(1961) clarified the particle-bubble interaction by introducing three-zone model for small and medium size particles. When the particle is far away from the bubble surface, the hydrodynamic forces are dominant. The particle is driven toward the bubble surface by the particle inertial and gravity. This region is regarded as Zone 1 and the interaction in this zone is a collision subprocess. As the particle gets close to the bubble, it exits a zone where the liquid flow around the bubble surface creates a tangential stream from the upper surface of the bubble toward the rear of the bubble. This is Zone 2 which is called the diffusiophoretic zone. In Zone 3, the particle is very closed to the bubble, surface forces like van der Waals, electrostatic and structural forces are considered. Contrast to Zone 1, Zone3 can be regarded as an attachment subprocess."

Jan 1, 2016

By P. G. Keohane, J. S. Drake

"Cominco's Polaris Mine is a lead-zinc underground operation that began commercial production in early 1982. The mine site is located on Little Cornwallis Island in the Canadian Arctic at a latitude of 75°23'N and at a longitude of 96°55'W. The nearest settlement, Resolute Bay, some 100 kilometres southeasterly from the mine, is accessed from the mine by light aircraft. The mine site can be accessed by sea during the six-week ice-free period each year. During this time all major operating supplies are brought to the mine and the lead and zinc concentrate products are shipped out to market.GeologyThe Polaris orebody lies near the top of the Thumb Mountain Formation of Ordovician age. This formation is a relatively homogeneous section of thin to medium bedded limestones which are brecciated and dolomitized in the area around the orebody. The deposit is described as a Mississippi Valley-type orebody. Ore minerals are sphalerite and galena with the waste being predominantly dolomite with calcite and marcasite. The ore is quite porous with voids being generally filled with ice as the mineralized zone lies entirely within permafrost. Reserves consist of about twenty million tonnes of ore grading 3.8% Pb and 14.3% Zn with a further three million tonnes of inferred ore at a slightly lower grade.The orebody strikes in a north-south direction with the hangingwall dipping at about twenty degrees to the east. It is generally conformable with the stratigraphy. The footwall in the western portion of the orebody, the Panhandle, lies about 10 to 30 metres below the hangingwall. To the east the footwall drops sharply, creating an orebody height of up to 110 metres in what is referred to as the Keel Zone. The Panhandle Zone has typically 80 - 110 metres of cover above the hangingwall , About 25% of the reserves are in the Panhandle Zone, the remainder being in the Keel Zone. Figure I illustrates a plan view of the orebody relative to other surface facilities on the property and Figure 2 illustrates a simplified section through the Panhandle and Keel Zones."

Jan 1, 1985

By E. L. Horner

"Srnoky River Coal is capable ofprocessing 3 million tonnes per year ofrun-of-mine coal at the Smoky River Coal preparation facilities to produce 2.1 million tonnes of high quality, low volatile coking coal for export markets. Multi-seam surface and underground mining operations are scheduled to maintain raw coal feed to the plant. Two beneficiating circuits wash the coal. A heavy medium cyclone circuit cleans the plus 0.5 mm coal and a froth flotation circuit cleans the minus 0.5 mm coal. Clean coal is thermally dried, loaded into unit trains, treated for dust suppression, and transported to west coast port facilitiesf or export. Plant by-products are used as thermal fuel Jn an adjacent power station. Quality control procedures ensure efficient resource recovery for a yield of uniform specification product, at a 7% ash level. Introduction Smoky River Coal operates surface and underground mines in the Smoky River coalfield. Approximately 3 million tonnes per year (mt/ a) of run-of-mine (ROM) coal can be processed at the coal preparation plant to provide 2.1 mt/ a of clean, high quality, low volatile bituminous coking coal. Coal is processed by heavy media and froth flotation cleaning circuits and is thermally dried.Raw Coal Characteristics The characteristics of the ROM coal, both in terms of quality and size consistency, vary with intrinsic seam qualities and mining methods employed. The two seams mined (No. 4 and No. 10) show distinctly different washability characteristics. Seam No. 4 contains relatively few middlings and can be readily cleaned by dense-medium cyclones and froth flotation to give a clean coal at specification ash content. Seam No. JO is more difficult to wash, and the ash content of the clean coal is higher than No. 4 seam at the same operating conditions. However, when the upper I m is excluded from the plant feed, the remaining lower section has washability characteristics similar to No. 4 seam. Coal mined by underground means sometimes contains caprock and consequently tends to be dirtier than similar coal mined by surface means."

Jan 1, 1985

By J. Ouellet

The authors participated in a study for a new mine shaft in Saskatchewan?s Athabasca Basin where ground freezing is desired to reduce water inflows. Constraints were imposed on the design in terms of permissible water leakage (less than 10 m3 / hour) inside the shaft. Since the shaft goes through highly permeable formations, water control measures had to be incorporated into the design. Ground freezing was selected as the most reliable and proven method for the sinking and a hydrostatic liner design was implemented. While exploring various technological options available for providing a fully hydrostatic liner, the authors came up with a new design concept that offers a more cost effective solution while meeting all the design constraints. The new liner concept is a composite design using concrete and a sprayed-on membrane system. A proof of concept program comprising laboratory testing and field testing was successfully implemented. This paper presents the innovative liner design, as well as the adapted sinking methodology, developed for this type of project. The new concept offers a new cost effective high performance hydrostatic mine shaft liner comparing favorably with traditional methods. RESUME: Les auteurs ont réalisé une étude pour un nouveau puits de mine dans le Bassin de l?Athabasca en Saskatchewan. Des limites sévères sont imposées sur le design en terme de volume d?infiltration d?eau acceptable (moins de 10 m3 / heure). Comme ce puits de mine traverse des formations très perméables la congélation des terrains a été sélectionnée, une méthode éprouvée et fiable. Un design hydrostatique a été choisi pour le revêtement du puits. Dans le processus de design, les différentes technologies disponibles ont été étudiées. Les auteurs ont développé un nouveau concept de revêtement composite offrant un rapport performance/prix plus avantageux que les technologies conventionnelles. Le nouveau design proposé est composé de béton et d?une membrane projetée. Un programme expérimental a été réalisé pour démontrer la faisabilité du concept. Cet article présente le nouveau concept ainsi que la méthodologie de fonçage de puits adaptée. Ce concept innovateur offre un revêtement hydrostatique performant à un cout avantageux par rapport aux techniques de construction utilisées jusqu'à maintenant.

Jun 1, 2012

By R. D. Lindsay

Originally the focus of Deak Resources Corporation Business Plan was to establish a method for treating small gold and possibly base metal mineral deposits located in the Kirkland Lake - Noranda area of Northeastern Ontario, Northwestern Quebec at a central treatment facility. Since the establishment of this original business plan in 1988 other processing options have availed themselves for handling the base metal ores off site at a central facility which may preclude their processing at Deak.The site selected for the Deak processing plant was Kerr Addison's Virginiatown operation. At the time this property was acquired from the Receiver following Golden Shield Resources' Bankruptcy in 1989 the mill had been processing in the order of 1, 100 SDT per calendar day through one processing module; a module originally designed to process 1,500 SDT/day of a free milling gold ore. This tonnage level however had not been achieved since 1966 when an average throughput of 1481 SDT per calendar day was recorded.In order to realize Deak's overall Business Plan it would be necessary to expand the mills processing capabilities to provide:(1) A 2200 SOT per day circuit capable of processing a free milling, medium work index gold ore;(2) a 1 ,000 SDT per day flotation and/or cyanidation circuit capable of processing refractory gold bearing materials containing refractory minerals (i.e. copper) that should be removed prior to cyanidation; and possibly(3) a 1200 to 1500 SDT/day base metal circuit capable of processing the broad range of Deaks' Base Metal Property ores. If this circuit were introduced it would be completed in two tonnage phases.Further, it was recognized when operations resumed under Deak in 1990 that the existing tailings dam was suitable for, and had sufficient capacity for additional gold tailings with necessary physical modifications and changes in disposal techniques (including the construction of containment storage cells) that would allow storage for an additional 3.4 million tons of gold ore tailings approximately 1.0 million of which has been deposited since 1990. The focus of Deak's long term tailings disposal strategy is to acquire the Barber Lake Basin which is currently adjoined to our main tailings system which will provide an additional 10 million tons of storage capacity.

Jan 1, 1993

By Theo. Koulomzine

"The property of Consolidated Central Cadillac Mines, Limited, consists of 1,103 acres formerly held by Central Cadillac Mines, Limited, and Wood Cadillac Mines, Limited. Both mines have been partly developed to depths of 565 and 1,000 feet respectively, and from 1939 to 1943 they produced gold, with small amounts of silver and tungsten, having a total value of $2,208,528 from 377,489 tons of ore. The average grade of the ore was $5.85 a ton . Less than 10 per cent of the ore hoisted was discarded by sorting. New development work, carried out since the former Wood property has been purchased by Central Cadillac, has shown that the tonnage indicated by mine workings and diamond drilling exceeds 2,000 tons per vertical foot.The property lies between the claims of Kewagama Gold Mines, Limited, and Pandora Cadillac Gold Mines, Limited, and straddles the Cadillac 'break' for a length of nearly 1 ½ miles. The main workings are 1 3/4 miles east of the well-known O'Brien gold mine.GEOLOGYOutcrops are very scarce, with none at all of the most important horizons, so that the general geology shown in Fig. 1 is deduced mostly from underground workings and diamond drilling. Fig. 2 is a vertical cross-section and Fig. 3 a longitudinal section through the ore zone.The ore lies within a belt of Blake River volcanics which is approximately 600 feet wide and is flanked on the north and south, respectively, by Cadillac and Kewagama sediments. All the formations have a nearly vertical attitude. The Blake River belt consists essentially of well sheared volcanic tulfs, but associated with these in the northern part are a number of bands of iron formation and the central part, to a width of 100 feet, is occupied by talc schists, making the Cadillac fault proper. Intruding the volcanics south of the Cadillac shear zone are dykes of two types- finegrained aplite or quartz albitite, and porphyry; both consist essentially of albite and quartz and are distinguishable only by the grain size. They have the general east-west trend of the formations they intrude."

Jan 1, 1954

By C. T. Wiliams, John B. Bush, John Lamb

"THE TOWN OF HEDLEY is in the valley of the Similkameen River, about 200 miles east of Vancouver and 25 miles north of the International Boundary between British Columbia and the State of Washington. The main ore deposits are located on Nickel Plate Mountain, northeast of the town.The outcrop of the Nickel Plate system of orebodies is at an elevation of 5,900 feet. It was discovered in 1898 by prospectors and sold in the following year to the Marcus Daly interests of Butte, Montana. Production commenced in 1904 under the name of Daly Reduction Company. In 1909 control passed into the hands of the Hedley Gold Mining Company. Operation of the mine continued until 1930, when exhaustion of known ore reserves forced it to close. Upon the recommendation of Paul Billingsley (3) the mine was optioned by the 1. W. Mercer Exploration Company in 1932. Production began once more in 1934 under the name of Kelowna Exploration Company Limited, and was practically continuous until August 1955, when the mine was again shut down. The name of the latter company was changed in 1951 to Kelowna Mines Hedley Limited.The Mascot Fraction, a small wedge-shaped claim lying astride the Nickel Plate orebodies, was mined by Hedley Mascot Gold Mines Limited between 1935 and 1949. The geological setting and structural control of ore are essentially the same as in the adjoining Nickel Plate Mine.Total production from all operations on Nickel Plate Mountain to the end of 1954 was approximately 3,800,000 tons of gold ore, with a gross value in excess of $48,000,000.General GeologyNickel Plate Mountain occupies the gentle westerly dipping limb of an asymmetrical anticline, the axis of which trends northeasterly. The rocks are composed of a thick pile of Triassic limestone, limy argillite, and quartzite, -resting on a flattish floor of granodiorite near the base of the mountain. Associated with these sediments is a host of porphyritic sills and dykes of gabbro-diorite composition. In the mine area east-west brown soda-rhyolite dykes and north-south black andesite dykes crosscut all the other formations and the ore, probably following steep later fractures."

Jan 1, 1949

By J. Koponen, K. S. Stadler, A. Fuerst, S. Gaulocher, Th. von Hoff, R. Veldsman

"Gearless mill drives (GMDs) are the workhorse in the mineral processing industries, more specifically when it comes to grinding crushed ore and cement (in various production stages) in semiautogenous (SAG) mills and large ball mills. They are renowned for their excellent reliability and robustness, long lifespan, and little need for maintenance, and thus yield a low total cost of ownership (TCO).A GMD represents a major investment for a mineral processing plant, and its availability is pivotal for the grinding process. As a basic rule, shut-down periods are to be minimized, but even much more important is that unscheduled shut-downs be avoided. In this contribution, we will present a portfolio of innovative remote diagnostic that consist of the following three key components:1. Trouble shooting is a form of corrective maintenance and is based on state-of-the art remote access technology, thus enabling highly skilled engineers to access the current sensor readings anytime and from anywhere in order to resolve urgent problems together with the GMD user.2. Periodic maintenance reports are a form of preventive and predictive maintenance and aim at continuous improvement based on long-term historical records and analyses of multiple measured signals. These detailed reports highlight the health and operational status of the GMD and are periodically (e.g. 3 months) submitted to the customer.3. Remote condition monitoring spans across preventive and predictive maintenance and is based on continuous recording and automatic analyses of relevant signals using advanced algorithms. The main issue is how to handle the enormous flood of data in an intelligent manner. The results of these analyses are made available to both the GMD user and supplier in real time in order to increase the availability and reliability of the GMD.In this paper, we consider various parts of the GMD, e.g. the cycloconverter, the ring motor, the auxiliary devices (e.g. cooling and lubrication systems), and also phenomena related to the mill itself (e.g. state and quantity of charge). The signal analysis techniques range from simple threshold-based analyses to complex time and frequency domain analyses. We will illustrate the benefits of the proposed approaches with some selected examples."

Jan 1, 2012

By I. Paredes, R. Díaz, H. Henao

Smelting of copper concentrate generates a significant amount of dusts which are collected in electrostatic precipitators. This material, which is a complex oxide of Cu, Fe, S, As, Sb, Bi and others, is difficult to recirculate into the smelting process due to the reported high concentration of arsenic. However, the dust also has concentration of copper above 10wt %, aside from reported contents of silver corresponding as much as 25wt% of the total inventories of this element in the smelters. Thus, it is of economic and environmental interest the development of a process able to reduce the concentration of arsenic in the dust and produce a material suitable to be recirculated into the smelting process. The present experimental work shows the results of a process of dust sulfidization-oxidition able to remove more than 65wt% of the arsenic present. INTRODUCTION Copper sulfide deposits worldwide exhibit increasing concentrations of arsenic. One case of interest would be the copper ores from the northern zone of Chile, which report high concentrations of enargite (Cu3AsS4) (Revista química, 2015) (Latinominería, 2014). The obtained concentrate from this ore is treated in a Fluidized Bed Roaster, producing calcines with low concentration of arsenic (<0.5 wt% As). This material is suitable to be treated in a Flash Furnace. At the roasting process, the arsenic is volatilized and then precipitated as fine particles of complex oxides. Most of this particulate material is removed from the gas stream through a device called Electrostatic Precipitator (Minería chilena, 2014). The experimental results reported in the literature indicate that arsenic present in these particulate materials (or dusts) cannot be eliminated in oxidizing atmospheres (air) or with inert gases (N2) in a Fluidized Bed Roaster even at temperatures as high as 700°C. There is also information that even the recovery of valuable metals from the dust is difficult through hydrometallurgical processes (private communication). This is how in some foundries these dusts are considered environmental liabilities. Regarding the decomposition of enargite (Cu3AsS4) in neutral atmosphere, it is reported in the literature (Padilla, 2001) that the main chemical reactions are:

Jan 1, 2019

By L. Bichler, C. J. Verdon

In this work, the effect of doping yttria stabilized zirconia (YSZ) with 5, 10 and 15 mol% erbium oxide (Er2O3, erbia) was investigated using spark plasma sintering (SPS) technique. Sintering was carried out at 1300°C with 30 and 60MPa uniaxial pressures and a 5min hold time. Densification kinetics were studied using displacement response from the SPS machine. As-sintered microstructure characterization was carried out via scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques, while chemical composition was characterized by energy dispersive X-ray spectroscopy (EDS). The results suggest that sintering carried out at 60MPa produced high density composites even though erbia dopants were found to inhibit material densification and grain growth during sintering. 5, 10 and 15mol% erbia- YSZ had cubic crystal structures, as verified by XRD analysis.

Jan 1, 2014

By H. Salamanca

HighService has developed different equipment using wireless technology and machine vision systems that were specially designed to allow 1) the online determination of the SAG mills liner&apos;s service life, 2) the automatic detection of a missing dipper tooth in mineral extraction shovels, 3) the reduction of accident risk potential in the mineral transportation within the mine, and 4) the reduction of collision risk potential between shovels and wheel dozers during mineral extraction. For the development of all these systems at HighService, extensive research has been done in radio frequency and image processing fields. The integration of both technologies with the expert knowledge of the company on the typical harsh environment conditions of the mining industry has led to the development of heavy duty equipment that tolerate the extreme mechanical requirements of SAG mills and electrical mining shovels.

Jan 1, 2007