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By J. E. Gill

Discovered in 1952, the deposits have been explored by diamond drilling on and near a group of islands in lake Nipissing and from under-ground workings. The ore mineral is a uranian pyrochlore. It occurs in breccia zones in association with calcite, apatite, a?cmite, feldsiiars, biotite, magnetite, sulphides, and fluorite in varying amounts. The pyrochlore concentrations occur in a steeply-dipping gneiss series with some crystalline limestone. Trends indicate a ring structure 114 miles in diameter. The main ore zone shows evidence of repeated brecciation and a succession of replacements .giving rise to a complex of rock types. Pegmatite and lamprophyre dykes cut the ore as do calcite-fluorite veins and later faults with small displacements. Columbium and uranium occur al-most exclusively in pyrochlore, but the proportions vary. There is no tantalum and only small amounts of titanium.

Jan 1, 1957

By H. G. Wang

The production process of a coal mine can often be interrupted by all kinds of events scheduled or unscheduled and thus often needs gas drainage for a temporary or long-term sealed area. Gas drainage has a relatively high risk, therefore attention must be paid to its design to keep the process safe. Based on the conservation laws of mass and constituents, and under the conditions of the allowable gas concentration limit in the return air route, the relationship between gas concentration and gas drainage flow rate as a function of time during the drainage process is discussed in detail to build a mathematical model of gas drainage from a sealed area. With respect to the gas drainage process, two different conditions need to be considered: one with a methane free fresh air supply, the other with a low gas concentration. This paper presents the derived mathematical models for these situations and then shows that they can be incorporated into one model with some modification. This combined model can be employed to determine the optimum gas drainage flow rate with the shortest drainage time. The application is coded using the C# programming language within the .NET framework. Finally, the application program developed by the author is used to validate the mathematical model through an example of gas drainage with varying rate.

Aug 1, 2013

By J. -C. Parisien-La Salle, D. Blais, G. P. Demopoulos

"In this work the dissolution, precipitation and adsorption behaviour of gold in acidic iron sulphate media containing small amounts of chloride ions is investigated via batch laboratory tests and OLI thermodynamic calculations over the temperature range 25-250°C. Chloride ions may be present in industrial pressure oxidation/pressure leaching (POX/PL) operations due to elevated water salinity levels or due to intentional addition as is the case of the CESL Copper Pressure Leaching Process. Thermodynamic calculations show that AuCl4 - may form depending on the free Cl-/Au ratio and temperature, its stability increasing with increasing Cl- concentration and decreasing with increasing temperature. On the other hand during POX/PL, we know that massive precipitation of iron in various hydrolysis products and compounds occurs. Hence of interest is the question how AuCl4 - that may form during leaching interacts with the iron precipitation products. Gold(III) chloride was found to co-precipitate with iron(III) (oxy) hydroxides and arsenates forming in the autoclave but not with natrojarosite. Upon further investigation it was discovered that activated carbon added in the autoclave (as done in CIL) acts as preferential sink for the mobilized gold, hence opening the potential for the development of a direct cyanide-free gold recovery process in acidic sulphate leach reactors.INTRODUCTIONThe recovery of gold from ores and concentrates has evolved over the years with processing routes becoming increasingly complex. Given the high value of gold, any reduction in losses during recovery operations constitutes an important economic benefit. One such loss that needs to be addressed is the potential solubilisation of gold during pressure oxidation (POX) of refractory sulphidic gold feedstocks. For example, Agnico Eagle Mines reported a loss in gold recovery due to the formation of a gold chloride complex (Garofalo, 2009). Gold is known to form complexes in solution, such as gold(III) chloride, if an excess of chloride ions are present. The fate of such soluble gold chloride during pressure oxidation and the subsequent neutralization of the acidic discharge slurry will determine if gold is lost or recovered in the downstream cyanidation operation. Thus it is of interest to know under what conditions gold chloride may stay soluble or co-precipitate along primary (formed in the autoclave) or secondary (formed during neutralization) precipitates. Furthermore, the mode of co-precipitated gold, such as adsorption on iron compounds, like goethite and hematite (Machesky et al., 1990; Nachayev, 1984); substitution in one of the precipitated phases; or finally chemical reduction to metallic state would have consequences in terms of gold recovery."

Jan 1, 2012

By J. B. Mitchell

Many of the pre-production and plant startup problems that we regard as inevitable are actually caused by poor organizational methods. Traditional methods of organization can be modified to provide clear definitions of responsibility, continuity and depth of involvement of key personnel in order to overcome these problems.

Jan 1, 1966

By C. Hilgendorf, J. Gingerich, J. R. Boniwell, M. Drouin, D. David on, J. Boldy

The initial discovery of gold in the Eastmain River area, 310 km northeast of Chibougamau, was made by Placer Development Limited in 1970. This discovery resulted from the drill testing of an airborne E .M. Target located in an area of extensive glacial overburden, within an unexplored Archean greens tone belt considered prospective for base metal deposits. Intermittent exploration by another company between 1973-1977 failed to obtain promising results and the existing claims were allowed to lapse. In 1981, Placer reactivated the project and initiated intensive exploration during the next two years which included aerial E .M. surveys, claim staking, ground E .M. and magnetic surveys, geological mapping, diamond drilling and attendant borehole P,E.M. surveys. Beginning in 1983, exploration has been conducted on a joint venture basis with Eldor Resources Limited, The greenstone belt under investigation has an arcuate distribution pattern relative to a centrally located granitic core. Occurrences of gold mineralization defined to date are located to the south of the granite along a strike length of 7 km, and appear to be restricted to the lowermost of two mafic volcanic cycles. This lower cycle is dominated by basaltic flows with subordinate rhyolitic flows and pyroclas ties. Concordant, variably magnetic, massive to talcose ultramafic units occur towards the stratigraphic top of the lower mafic volcanic cycle and appear to crudely define areas considered prospective for gold on a regional bases. Economic interest in centered on a s tratabound, siliceous, sulphide-bearing unit hosted in a 15- 25 metre thick sequence of rhyolite tuffs, basalts and intercalated ultramafics, The siliceous ore bearing unit ( interpreted as a recrystallized chert) contains from 10%-30% pyrrhotite and pyrite with subordinate chalcopyri te and minor sphaleri te. Alteration is characterized by mica development, silicification and carbonatization. Garnets are also occasionally present in close proximity to the ore horizon. The sequence is south facing, and overturned to the northeast at 35°-55°. Explora tory drilling in the vicinity of two conductive targets has been on 100 metre centres along a 1 km strike length of the prospective sequence. To the end of 1983, two ore zones (A and B) have been partially drill tested with estimated indicated and inferred geological reserves of 1 million tonnes grading 11.7 g/t gold , 14.7 g/t silver and 0.26% copper. The system is open at depth. This discovery is the result of the effective integration of geophysics and geology with contributions by many over a long period of time. Key events that can be emphasized are: ( 1) initial area selection of a remote greenstone belt in 1969 - albeit for base metal deposits , (2) utilization of an airborne E .M. system which successfully targeted the A Zone in 1970 , (3) the timely reactivation of the project in 1981 and the subsequent recognition that the original discovery represented a sulphide bearing stratabound horizon with implicit volcanogenic connotations , (4) the intensive effort in 1982-83 deploying aerial and ground geophysics coupled to volcanogenic concepts of ore distribution which resulted in the discovery of the B and C Zones in 1982, and (5) the integration of downhole P . E.M. surveys and geology to successfully delineate ore at increasing depths . To the end of 1983 , $2.6 million has been expended, and it is hoped that continued effort will result in the eventual delineation of an economically viable ore deposit for the joint venture partners .

Jan 1, 1984

By A. McLean, Q. R. Yang, Y. D. Yang, G. F. Zhang, P. Wu

A considerable amount of waste slag from the pyrite roasting process is discharged every year. Recovery of iron from the waste slag is of great interest for comprehensive use of mineral resource, reduction of environment impact and improvement of economical benefit to related companies. The objectives of the present work are focused on: (1) Compare various procedures for recovery of iron from the waste slag and select a best procedure for industrial trial which is roasting of the waste slag under reducing condition followed by magnetic separation; (2) Investigate the optimum conditions for maximum recovery of iron from the waste slag. The experimental result shows that under the treatment condition found in this work about 36 to 40% of the iron oxide was recovered from the waste slag, where the iron content in the concentrate is 57%. The total recovery ratio of iron, up to 70%, from the waste slag was achieved. After the treatment, sulphur content in the waste slag was reduced significantly and gangue materials, such as SiO2, Al2O3 and TiO2, were reduced effectively.

Jan 1, 2011

By Edgar Stanfield

Since April, 1923, the Scientific & Industrial Research Council of Alberta has had an analyst, Mr. W. P. Campbell, steadily employed analyzing coal samples taken by the provincial Mine Inspectors. Mr. Campbell has also analyzed a number of coal samples taken by one of the Council's Geological Survey parties. We have thus, at the time of writing, over four hundred analyses of Alberta coal, made by the same analyst, and strictly comparable. These samples come from widely distributed points, some 88 townships being represented. The stream of samples is still flowing in, and it is hoped by the end of this year that the number of townships represented will be increased at least fifty percent. The time has arrived to publish some of the data collected; but it must be clearly understood that this is merely a progress report, subject to revision as further information is obtained. Three hundred and fifty-three coal mines in the province were operated during 1923. The production per mine varied from 5 up to 500,000 tons. With this number of mines to examine (and fresh mines are being opened every year) it is a large task to make even a proximate analysis of representative samples from every mine. Any chemist will appreciate the fact that to make ultimate analyses representative of even the larger mines will be a long and tedious task. It has seemed better to make a comprehensive survey by proximate analysis and determination of calorific value before beginning the more thorough survey by ultimate analysis. This paper, therefore, deals only with proximate analyses and calorific values; and, owing to limitations of time and space, does not deal with other chemical and physical characteristics of coal, such as storage quality and fusibility of ash, important though these are.

Jan 1, 1925

By P. Cicmanec

Mining activities in the territory of Slovakia have a long history. Mining techniques have developed rapidly in the last centuries. This paper deals not only with mining history, but also with underground brown coal mining, magnesite mining and other mining activities at present and sustainable developments of the mining industry in the Slovak Republic. This paper looks forward in the context of mineral raw materials in Europe (Global Europe, 2012).

Aug 1, 2013

By D. M. Muir

Many plants produce iron(II)/(III) waste liquors which must be treated by neutralisation and precipitation to remove the iron. Iron can be precipitated as crystalline goethite or jarosite by controlled oxidation at low pH and as magnetite by controlled oxidation at high pH, but only at elevated temperatures (>70°C). This study focuses on the characterisation and settling properties of the iron oxides produced at ambient temperatures using various neutralising agents in order to improve the performance of thickeners. It was found that two-stage addition of caustic to FeC12 solutions produced a fast settling material characterised by Mossbauer spectroscopy and XRD as maghemite and magnetite. However, lime and magnesia additions resulted in more ferrihydrite formation and much lower settling rates because of the enhanced oxidation of Fe(II) by air. Settling rates decreased significantly as the proportion of Fe(III) to Fe(II) in the liquor increased. The mechanism of iron oxide precipitation is discussed together with some reasons for the different behaviour of the neutralising agents.

Jan 1, 2006

By Arthur Brant

STEEPROCK LAKE (Figure 1) lies about two miles north of Atikokan, a village approximately one hundred and forty miles west of Fort William and one hundred miles east of Fort Frances on the Canadian National railway. The possible presence of hematite beneath the waters of Middle arm was inferred by early geological investigators (1890-1903) from the dense hematite float found on the southerly shores of this portion of the lake (1). A dip-needle survey of Middle arm, undertaken in the winter of 1930-31 by J. G. Cross, indicated two areas of high magnetic attraction which Mr. Cross thought might be due to magnetic iron oxides associated with possible hematite bodies. Bedrock could not be reached by the ineffectual hand-drilling so courageously attempted, and further work was abandoned. It was not until 1937 that Mr. Jos. Errington, of Toronto, convinced of the possibilities, determined to support Mr. Cross to the extent of several thousand feet of drilling. During the winter of 1937-38, holes Nos. 1, 3, 4, 5, and 13 were put down (see Figure 1). The first four of these holes demonstrated that the areas of magnetic attraction outlined by the dip-needle survey east of the Narrows and southwest of Elbow point were due to ash rock (2). As a result, Mr. Cross decided to investigate the bordering areas of low magnetic attraction and selected a location near the high ferruginous lime (3) point in the northeast of Middle arm. Dense, hard hematite beneath approximately 350 feet of water and clay was struck in the first hole, and, before the end of the winter's drilling, hematite had been encountered in holes Nos. 6 to 13 along a straight line 700 feet in length (see Figure 1). In the meantime, the Steerola ( 4) Exploration Company had been formed to continue development and already, in the spring of 1938, W. D. Neeland, the Company geologist, had come to the conclusion that the most probable location for possible hematite was at the ash-lime contact. Accordingly, during the summer, drilling was continued off-shore in holes Nos. 15, 25, and 27 (see Figure 2) toward possible hematite bodies inferred by Mr. Neeland.

Jan 1, 1940

By A. Hayatdavoudi, K. G. Sawant, F. Boukadi

"In this work, we found that contact between shale and water results in development of micro fractures. Based on results of experiments on Pierre shale, we conclude that appearance of micro fractures begin with saturation of capillaries, ionic and diffusive transport of water into the shale clays and once capillaries are saturated, the cause of micro fracture propagation is the conversion of ionic activity/exchange to excess pressure that did not exist before fracking. Based on these findings, the spread of micro fractures appear to be a time-dependent phenomenon which has not been addressed in the existing macro/micro fracture models.INTRODUCTIONShale has often been involved as a hazard in drilling operations. This hazard can be defined as “destabilization” of shale. When contacted with water-based drilling fluids, some shales readily swell and sometimes, cause the wellbore to cave-in, slough, wash-out, close, and pack-off, impeding the drilling by sticking the drill-pipe. However, once drilling reaches the desired depth or length, the casing is set, cemented, and perforated, and then actually we wish to initiate fractures and destabilize the shale formation, using hydraulic fracturing.Clays constitute a major portion of minerals in shale. These clays contain a large amount of free energy which is the main factor for “slick” water adsorption/absorption. In fact, the reason for using “surfactants” in hydraulic fracturing fluids is to make the penetration of the fluid into the capillaries much easier, thus water meets with less resistance to enter the small capillaries. Also, the result of high capillary suction pressure is due to small Angstrom size capillaries, smaller pores and presence of ions and hydrateable metal atoms. The free energy is thus, related to all the above mentioned and other affects. Capillary pressure, osmotic pressure and other pressures are responsible for creating the micro-fractures in shale, thus, increasing the network of micro-fractures which leads to more gas production. The objective of this study is to evaluate the pressures of the individual ions which are released by the diffusing “slick” water into shale. These pressures would be added to the above mentioned capillary pressure, osmotic pressure, bacterially-induced pressures, chemically-induced reaction pressure, pressure due to exchangeable ion-transport, pressure due to release of free energy of solvation and eventually to the pore pressure as suggested by Terzaghi’s equation."

Jan 1, 2015

By S. P. Narayan

The hot deformation behavior of Pure Mg and Mg-0.29Ce alloy were studied by isothermal hot compression tests in the temperature range of 250 - 500°C and strain rate range of 10-3 - 102 s-1 in a computer-controlled 50kN servo hydraulic universal testing machine (UTM). The results show that the flow stress of Mg pure and Mg-0.29Ce alloy increases with strain rate and decreases after a peak value, indicating dynamic recovery and recrystallization. Process efficiency was increased by nearly 10 to 12% by addition of Ce in Mg. Mg pure exhibits instability zones between 250-275°C at 10 ? 102 s-1 and 400¬500°C at 101 ? 102 s-1 temperatures and strain rates respectively, rest is the safe deformation zone. Wherein, Mg-0.29 Ce exhibits two low efficiency zones from 250 ? 300°C at 10-2? 10° s-1, 400 ? 500°C at 101 ? 102s-1 and high efficiency zone at 450 ? 500°C at 10-3? 10-1s-1. 4D process maps were generated for the above said alloys which illustrate contours of power dissipation and instability in the 3D space of strain rate, temperature and strain.

Jan 1, 2011

By Neo Molelekeng, Jocelyn Bouchard, Rebecca Monnapula, Martin Émond

"Xstrata Alloys – Eland Platinum concentrator (South Africa) has recently been commissioned and is now initiating a challenging optimisation program encompassing the entire operation. Process control improvements are key elements of the program and initial results have demonstrated how leveraging from current assets can bring significant improvements through overall reduction of variability. This paper gives a brief overview of the operations and details how Eland is striving to become a top tier leader with advanced regulatory control strategies recently implemented. Results reveal that what can be achieved in a standard control system (PLC or DCS) should not be underestimated as the first interventions led to a steadier operation of the primary ball mill circuit. Following the improvements, significant and sustained reductions of standard variation were observed for key process variables around their set-point: primary ball mill feed rate (72 %), rougher feed density (58 %), and rougher feed flow rate (47 %). A path forward has been identified to tackle further opportunities around the primary grinding circuit: water balance management, throughput optimisation as well as charge and power draw control.INTRODUCTIONThere are numerous approaches to mineral processing plant optimisation. As the benefits of determining the right reagent types, mix, dosage and addition points, or the proper charge of grinding media in a mill are fully appreciated, there is still nowadays some misunderstanding and misconceptions about process control in general and how it can contribute to the whole optimisation process. The confusion between the various disciplines involved, i.e. instrumentation, control system programming, automation and process control, certainly does not serve the best interest of the industry with this regard."

Jan 1, 2010

By W. G. Hubler

It has been within only the last two or three years that enough progress has been made in preferential flotation to warrant metallurgists in recommending the installation of commercial-sized plants for the treatment of copper-zinc-iron ores. Until the new processes had been worked out successfully, the treatment of this type of ore had proved a stumbling block in the path of metallurgical progress. Separation of lead-zinc ore is comparatively simple. A lead-zinc ore low in iron may be separated and concentrated by gravity con-centration, provided it is not necessary to grind too fine. Owing to the specific gravity of chalcopyrite and sphalerite being so nearly the same, however, their separation by gravity concentration is out of the question. Complex lead-zinc-iron ores in which the several minerals are intimately associated, requiring fine grinding to free them, have been successfully treated by flotation for the past fifteen years. Galena is easily floated, and its flotation, unlike that of chal¬copyrite, is not affected by the reagents used to inhibit the flotation of sphalerite and iron sulphides. When an attempt was made to use the methods of lead-zinc se-paration on copper-zinc ores, it was found that the depressant re-agents added to inhibit the flotation of the iron and zinc minerals would, under certain conditions, depress a large part of the copper. It was also recognized that, in the grinding of copper-zinc ore, soluble salts were generated which were detrimental to flotation unless properly controlled. The main part of this paper will be a discussion of solutions in the grinding circuit in relation to the pro¬duction of soluble salts and their effect on flotation.

Jan 1, 1931

By J. W. Reynolds

Introduction The Sullivan mine, at Kimberley, B.C., is the principal source of ore for the Consolidated Mining and Smelting Company of Canada, Limited. Current production amounts to about 2,500,000 tons of lead-zinc ore a year. With approximately 1,600,000 feet of percussion drilling and 700,000 feet of diamond drilling being carried on each year, any improvements in drilling practice are important. Testing of new equipment and drill bits is a major function of the Testing Department at the mine. Tungsten carbide bits have been the subject of many tests since 1947 and have been used in operations since 1948. This paper details with the methods of testing and gives comparative data on performance and costs for tungsten carbide bits as compared to steel bits. Operational use of tungsten carbide bits started in April, 1948, and the extent of application has increased considerably since that time. The scale of employment is illustrated in Table I, which also shows other statistics on the use of carbide bits. Up to the present time eighteen types of carbide bits or tipped steel, as made by six different manufacturers, have been tested. In general, one supplier's bits have been used in operations, but some large-scale operational tests have been carried out with other types. The types tried are shown in Table II. To date they have been, the subject of 33 tests, covering the destruction of 804 bits over an observed footage of 42,586 feet.

Jan 1, 1951

"One of the corporate values mentioned by many companies deals with respect for people. This paper discusses one aspect of this value, namely, the need for clarity of accountabilities and authorities. The job of the manager in achieving this goal is analyzed and the benefits of enhancing the manager-employee conversation outlined. IntroductionCorporate values usually refer to the standards of behaviour that the leaders of the organization expect of all employees, including themselves, in carrying out their duties. Terms such as integrity, respect for the individual, continuous improvement, continuous learning, teamwork, speed, and innovation are quite common. The company-specific values are typically developed by the top executives of the company, and then tested with a broader group of employees. Where the process works, employees have a good understanding of what behaviour is expected of them in doing their work, in making difficult decisions, and in interacting with others.Having spent considerable time in his career investigating and studying the management systems at over 50 of the most successful companies in Canada, the United States, Europe and Japan, the author has had the opportunity to visit organizations such as Hewlett-Packard, 3M, Xerox, Intel, Toyota, NEC, Komatsu, British Airways, and Eastman Chemical. These experiences, together with the work of many other researchers, including the work of Dr. Elliott Jacques, have helped significantly to form the thoughts expressed below.Rather than reviewing the creation of corporate values and their deployment through the organization, these remarks focus on issues over which managers and employees have some control. The value in which managers can have significant impact deals with people and the respect shown them in the workplace. The component of respect to be emphasized is to be clear about expectations or accountabilities for oneself and the people who report to you, and to ensure that personal authority matches those expectations."

Jan 1, 1999

By R. Hammen, J. Lifton

"The purification of rare earth elements (REE) at mining operations is traditionally accomplished by multiple chemical phase-transfer processes including precipitation, solvent extraction, and ion exchange. We describe REE purification results with Solid Phase Extraction (SPE) columns that were developed to improve the speed and economy of REE purification. The SPE columns have the properties of enhanced equilibration kinetics, so that residence time of a few seconds will accomplish selective chemical transfers from solution phase to solid phase. We describe the separation of REE’s as a class from leach solutions and the further purification of REE salts. INTRODUCTIONHistorically the rare earths were first chemically separated from each other and purified by fractional crystallization. This slow, cumbersome, and laborious process was not suited to commercial production. Solvent Exchange (SX) technology was applied to the problem of separating and purifying the rare earth elements when it was determined in the late 1960s that there might be commercial uses for them individually. At the same time the very slow and expensive technique of ion exchange was applied either for ultra-purification of the desired “light” rare earths, or for the recovery and purification of the tiny amounts of higher atomic numbered, “heavy,” rare earths. Solvent Exchange (SX) has today become the standard for separating the rare earths across their atomic number spectrum. Whereas the separation of the light rare earths commercially may take 30 “cascades’ in a modern Chinese plant, the total separation of all of them from each other may take up to 80 such “cascades,” and is only even “practical’ with preconcentrated feed stocks, such as those produced in China by heap-leaching techniques performed in situ on very low grade radio-nuclide free ionic absorption clays.. Ultra-pure materials of all types are produced today by ion-exchange processing of ionic species already separated by solvent exchange.Hard rock deposits and refractory residues of tin mining and residues from uranium mining have been identified outside of China with very high ratios of dysprosium and other heavy rare earths to the majority lighter ones. Several issues face those who wish to process these materials so as to separate the heavy rare earths commercially:"

Jan 1, 2012

By Namavari. H., M. Ashouri, M. R. Sarhadi, S. H. Mansouri, A. Sarrafi

The splash phenomenon and its effective parameters in metallurgical converters have been studied thoroughly for decades. The detailed studies of processes such as tuyere blockage, wave formation during air injection, entrapped phases, and also processes which control the formation of bubbles in viscous fluids are not feasible yet. In this research, we have used a converter-shaped vessel made of flexi-glass. Water and oil have been used as matte and slag phases respectively. The effective operational factors responsible for creation of splashing have been studied such as air flow rate, tuyere angles, depth of tuyere submergence, tuyere blockage, density and viscosity of liquids, liquids heights, etc. The results have been found as follows: the amount of splashing increases slowly as air flow rate increases. However, as the air flow rate reaches a critical value (depending on the physical specification of converter) the amount of splashing rises sharply, because the flow of air inside the liquid changes from bubbling into a jet stream; and most of the splashed materials are in the form of filaments instead of droplets. Changing tuyere angle from horizontal towards vertical position will increase the turbulence level on the fluid surface and causes an increase in the amount of splashing. The effect of tuyere submergence is related to the converter opening angle. As the converter opening angle is shifted towards the hood position, the amount of tuyere submergence and splashing will increase. As density of the liquid increases, the number of droplets splashing increases with a decrease in drop size. Therefore, the total amount of splashing decreases. However, as viscosity of the liquid increases, the splashing material increases due to the changes in the splashed material from droplet shape into filament form. The height of liquid inside the converter, depending on the relative height of heavy phase and light phase, is an important parameter regarding splashing. As the relative height of heavy phase to light phase increases the splashing will decrease. The tuyere blockage will cause the pressure in the inlet manifold to increase; and in real cases will increase the splashing. Finally, we have development a model based on dimensional analysis to relate the above parameters in order to calculate the amount of splashed material.

Jan 1, 2007

By R. Agius, A. Nacu

"Cyanide destruction technologies are implemented at gold and silver operations to comply with the International Cyanide Management Code and meet ever more stringent discharge limits. Currently, the most common chemical cyanide destruction processes used in industry are sulfur dioxide/oxygen, hydrogen peroxide, and Caro’s acid. The cyanide destruction process used at an operation must reliably generate streams of acceptable quality at all times, and depends on numerous factors, including permit discharge requirements, tailings chemistry, location, site-specific climatic conditions and size of the operation. Selecting the most appropriate cyanide destruction process and determining the process design criteria requires accurate laboratory testing. This paper presents and discusses the results of a number of cyanide destruction evaluations that have been conducted to reduce cyanide concentration in process solutions or cyanidation tails. Laboratory testing provides important insights into reagent consumption and other factors required to achieve the target residual weak acid dissociable cyanide (CNWAD) levels.INTRODUCTION Process solutions associated with the extraction of gold and silver contain several forms of cyanide. The most toxic form of cyanide is free cyanide, which can be present as a dissociated cyanide anion (CN-) or gaseous or aqueous HCN. Weak or moderately stable cyanide complexes such as those of zinc, copper and nickel are classified as weak acid dissociable (CNWAD). Although less toxic than free cyanide, weak acid dissociable cyanide complexes are considered “ecologically sensitive” forms of cyanide and are regulated in most jurisdictions. In practice, reported WAD cyanide values comprises both free cyanide and weak acid dissociable cyanide complexes. Cyanide complexes with gold, mercury, cobalt and iron are referred to as strong acid dissociable complexes (CNSAD) and are much more stable, even under mildly acidic conditions. Another term commonly used in cyanide chemistry is total cyanide, which represents all cyanide compounds present in solution. Total cyanide levels in solutions are always equal to or higher than WAD cyanide values and the difference between the two usually indicates the presence of iron-cyanide compounds. Typically in Canada, CNTOTAL levels cannot exceed 1 mg/L in solutions discharged to the environment."

Jan 1, 2017

By C. Gu

Flow field design is critical for PEM fuel cells. The flow field design can affect reactant distribution to the catalyst surface, water management, thermal management and current collection. Therefore, it has tremendous impacts on the fuel cell performance and durability as well as reliability and operational flexibility. In this paper, an optical method is used to study the reactant distribution in the flow field channels of two commonly used flow field designs, straight channel design and serpentine channel design. Images of the flow patterns are shown followed by discussions of the flow patterns.

Jan 1, 2005