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By B. Morrison

"The Kiruna Electric System is a recently developed inclined ore haul age system for underground mining operations. Although an initial investigation was carried out at the Swedish underground iron ore mine LKAB almost three decades ago, it was not until 1981 that the resources of LKAB, ASEA and Kiruna Truck AB were combined to investigate, and subsequently develop an ""all- electric truck"" for the mining industry.It has long been appreciated, that major economical advantages could be realized by a mining operation through an extension of the cost-effective life of the existing ore hoisting system by the use of ramps to haul ore up to the main haulage level. Diesel truck s have been used and are being used for ramp haulage. Their use however, is limited due to ventilation and operating costs restraints.There are numerous instances of orebodies, located within a couple of hundred metre s of surface, or below an existing hoisting facility, being developed by ramp access while the shaft is being sunk. Development of an orebody via ramp access has many advantages to a mining operation where mechanized mining is to be practiced. These advantages are both practical and economical; generally falling within the over-all umbrella of the phrase ""cash flow"" mining.The decision to sink a shaft is a major committment by any mining company, regardless of size and financial reserves. Extensive diamond drilling, both shallow and deep must be carried out before a decision can be executed. This constitutes a major financial expenditure over an extended period of time.The decision to sink a shaft must be weighed against the reliability of geological interpretation of the deep diamond drilling results, the stability of the mineral market and potential fluctuation in ore prices and interest rates."

Jan 1, 1989

By A. G. Matyas, B. Wasmund, R. C. Francki, K. M. Donaldson

"The construction of large. high-power electric furnaces has been an important factor in the growth of electric smelting technology . New developments in the design and operation of electric furnaces have been spurred by the escalating cost of electric power and increasingly stringent environmental constraints. Key areasofprogress include the application of high voltage to enhance furnace productivity; the installation of novel furnace cooling elements and robust binding systems to extend furnace life; development of process schemes to reduce power consumption by preheating and prereduction of the charge; and environmental control improvements for handling fine dusty feedstocks, and for furnace sealing.This paper reviews these developments and outlines a systematic approach for their application in the custom design of new or retrofit electric furnace facilities.IntroductionThe use of electric smelting furnaces has continued to progress during the last decade. Electric furnaces offer high throughput capacity and productivity. In addition, they produce minimum environmental impact, as the furnaces can be readily sealed, and only a small quantity of off-gas is generated. Electric furnaces present the most favourable choice of smelting technology where high process temperatures in excess of about l400°C are required.Their application is burdened by the escalating cost of electric power, hence it is important to seek new opportunities through further technological development. This paper reviews recent developments in the design and operation of high-power electric smelting furnaces, in the following areas:"

Jan 1, 1993

By Bertrand Wolfman, William E. Stanley

"This paper reviews the traditional mine accounting systems, including ""custodial accounting"" and unit costing, and then suggests that the use of flexible budgets represents a more suitable method of reporting costs in order to assist the mine manager in improving productivity. Examples of various applications are given to show that the result is a clear reporting structure.Custodial Accounting is Emphasized in Traditional SystemsTraditional mine accounting has been mainly concerned with the accuracy of financial reporting to ""head office"" for the use of the directors and the company's bankers and shareholders. This is often called custodial accounting and it represented the main purpose of accounting when first developed in Europe hundreds of years ago. This important development permitted the establishment of enterprises which were separated from their owners because they could rely on accurate financial reports of management's stewardship.As custodial accounting is fairly broad and historical in nature, it is often not very useful to the mine manager for ongoing monitoring of performance of mining, milling, maintenance, and other support and staff groups. In spite of the considerable investment in accounting staff and computer support, many accounting systems have not been upgraded so that they accurately reflect workplace performance on a weekly or monthly basis.Budgets are Often FixedMany mines today also still emphasize fixed budgets. Thus, the mine plan which is set in the fall of one year is converted to a monthly tonnage and detailed dollar budget for periods of up to sixteen months in the future. The only certainty in this plan is that actual events will differ; timing, mix of mining methods and production volumes will differ on a monthly basis.Unfortunately, the fixed budget has no capability to reflect these operational changes. It is frozen for the full year. The result is that actual results will inevitably be compared to an outdated target."

Jan 1, 1982

By T. Schmidt, H. Assadi, F. Gartner, H. Kreye

Among all spraying processes, cold spraying has attracted a special attention in recent years, both as a coating - and more recently - as a rapid manufacturing technique. The interest in this process is mainly because of the fact that the deposition of spray material takes place at moderately low temperatures, and thus, oxidation and unfavourable microstructural changes can be alleviated. In this process, a highly compressed gas, flowing through a de Laval nozzle, accelerates the particles of the spray powder to high velocities of up to 1200 m/s. Although there is no melting of particles prior to impact on the substrate, cold-sprayed deposits can be denser and more tightly bonded as compared to the equivalent deposits produced by conventional thermal spraying methods. The present contribution focuses on this unique aspect of cold spraying. Modelling of particle impact, combined with various experimental observations, is employed to illustrate that bonding of particles and hence material deposition occurs through shear instability - associated with severe plastic deformation and localized heat generation - at the interacting surfaces of particles and substrate. The results of modelling also provide an insight to the influence of material and process parameters on the critical velocity and on the microstructural properties of cold-sprayed deposits.

Jan 1, 2006

By Dave N. K., T. P. Lim

"A fast, reliable and accurate method for radium-226 determination in environmental water samples has been devised, using an alpha spectroscopic technique. The correlation between barium-133 and radium-226 in the barium-radium sulphate precipitation mechanism was studied and in the limited experimental recovery range, the coefficient of correlation was r = 0.986. A self-absorption study for various barium carrier concentrations was also undertaken to obtain the least broadening of alpha energy line widths. An optimum value of 0.3 mg barium carrier was obtained for chemical recovery in the range of 85%.IntroductionWith the increase in uranium mining activities, the migration and spread of radioactivity via various environmental pathways is of great concern. Because of its inherent biological hazard and relatively long half-life, (approximately 1620 years), raidum-226 is frequently monitored as a measure of radioactive contamination of the environment. It is, therefore, necessary to modify existing methods for rapid determination of radium-226 in environmental samples for quick corrective measures in the event of seepage, dam leakage or discharge violations."

Jan 1, 1981

By J. I. Jr. Moore

Many articles have been written about the various operations of Britannia mines and mill, as well as treatises on the geology and ore deposits. A partial list of these papers is given below. Most of these papers have covered well the history of Britannia, and have included a thorough discussion of the geology and ore deposits; therefore, in this paper, no account of these subjects. is necessary. However, a short description of the ore deposits will be given as an aid to a clear understanding of the descriptions of the various mining methods. The Ore Deposits The ore deposits at Britannia occur along a shear zone and are five in number, named for the claims in which they lie, as follows: Jane, Bluff, Fairview, Empress, and Victoria. Each of these deposits is called a mine, as they are separated by 500 to 1,000 feet of barren ground. The Jane mine, although the first producer of the Britannia group, has not been in operation for a number of years. The deposit is a silicified replacement in sediments; with very little evidence of shearing. The Bluff deposit is a highly silicified replacement in porphyry, massive and irregular, very hard in the upper 600 feet with practically no shearing, and softer within chlorite schist in its lower 1,000 feet . The Fairview deposit consists of a series of twelve distinct veins or lodes, rather lenticular in shape, and occasionally merging.

Jan 1, 1928

By S. Sopher, C. Barsotti

"Inco Gold Company was created in 1987 as an unincorporated business unit of Inco Limited. In 1988, Inco Gold Management Inc. was incorporated to supply management, exploration and engineering services to this unit. The first new project, at Casa Berardi, Quebec, was brought to production in September 1988, less than two years after completion of exploration. For 1989, Inco Gold's exploration and capital expenditures have been budgeted at approximately $94 million, a record level. Inco Gold holds interests in more than 80 precious metals ventures and prospects in Canada, the United States, Brazil, Indonesia, Papua New Guinea and France. The most advanced projects, in addition to Casa Berardi, are at Mineral Hill, Jardine, Montana, where initial production is anticipated in the third quarter of1989, and Crixas in central Brazil, where production is scheduled to begin during the fourth quarter of the same year.BackgroundTraditionally, Inco Limited's mineral exploration has concentrated on nickel and other base metals but since the early 1980s Inco's exploration activity has focussed strongly on precious metals, principally gold. As a result, three deposits have been discovered and developed . In order to accelerate the establishment of a strong gold mining enterprise with its own specific growth and profit objectives, Inco Gold Company was created in 1987 as an unincorporated business unit. At the end of 1988 Inco Gold's share of drill-indicated gold reserves was approximately 14 million short tons containing 3.4 million ounces of gold.At Casa Berardi in northwestern Quebec, one mine is in production and another is planned to open in 1990. Properties at Crixas in Brazil and at Jardine, Montana, U.S.A., were being readied for production in 1989. By 1991, Inco Gold's share of gold production is expected to be 125 000 ounces with a target of 400 000 ounces annually by the mid-1990s."

Jan 1, 1990

By J. S. Scott

"The Quemont property comprises 640 acres lying directly north of and adjoining the Noranda (Horne) mine. During 1926 to 1928, United Verde Extension Mining Corporation sank a shaft 235 feet and did 3,000 feet of development work on the 215-foot level. Between 1929 and 1930, Quemonr Mining Corporation deepened the shaft to 926 feet, and did further lateral work and drilling on the 500- and 900-foot levels. This work was confined to an area close to the south boundary and met with little encouragement.Following a period of idleness a magnetic survey was made in the winter of 1944, followed in the summer of the same year by some 6,000 feet of drilling. The first successful hole was drilled in February, 1945, from the ice of Osisko lake.To the time of writing, 131,000 feet of drilling, surface and underground,have indicated a large tonnage of gold-silver-copper-zinc ore, and although some knowledge of the geology and structure is emerging, it is too early to draw definite conclusions. The following brief description deals only with those structural features that are reasonably well indicated."

Jan 1, 1954

By K. Nikkhah, N. Dhadli, G. Freeman

Ammoniacal pressure leaching operations have been in commercial use at the Fort Saskatchewan refinery of Sherritt International Corporation since 1954. Recent improvements have significantly increased the capacity of this circuit. The computer modeling of this process has proved to be a valuable tool in facilitating the evaluation of different operating scenarios in an effective manner. Reagent response in the ammonia leach of nickel and cobalt sulphides is examined using the dynamic process simulation capabilities of IDEAS(TM) software. The dynamic simulation enables accurate measurement of the sensitivity of the process to variables such as temperature, feed rate and ammonia concentration as well as compartmental analysis of metals concentration, pulp density, vent gas composition, and the formation of specific complexes. The complexity of the ammonia leach process makes it a logical choice for evaluation by computational analysis. The methodology for dynamic modeling of a pressure leach process is presented.

Jan 1, 2005

By B. L. Dorey

"Performance management is a systematic, practical approach to managing people. It is founded on some basic assumptions about people and is designed to focus on people in the work place. Organizing meaningful information and using it to involve people is a cornerstone of this system.Some common sense practices are developed to involve people in an organization's effort to improve performance. The successful implementation of this program requires solid commitment and total involvement from all levels of supervision and employees for maximum results and lasting impact. All levels of supervision participate in training sessions to tailor the systems for implementation in their areas. This style of management is data-oriented and the bottom line of success is to measurably improve performance. Basic Assumptions about PeopleMost people in an organization, regardless of level, take pride in their work and generally want to do a good job. When performance falls off, there is usually some explanation other than the employee not really caring. People like to know their exact responsibilities and clearly what is expected of them. People like to know where they stand with the boss and would like to be evaluated on what they do and accomplish, rather than on what others think or feel about them. Further, people like to be rewarded for their good results, indeed, to understand what motivates people, we must look at what happens as a result of their actions. Another belief is that supervisors often have a greater influence on the performance of their people than they fully realize. Simply letting people know how important their performance is can have an impact. The Key ElementsGiven these basic assumptions and beliefs about people, some common sense practices have been systematically developed to manage more effectively."

Jan 1, 1989

By George R. White

"The Phalen Colliery, the Cape Breton Development Corporation's flagship, is now producing thermal and metallurgical grade coal in Eastern Canada's Sydney Coal Field. The colliery is a drift mine operating under the waters of the Atlantic Ocean. Improved mechanization, including a 2200 tonne per hour cable conveyor, and the introduction of modern retreat longwall mining methods as part of the Phalen concept are now paying off in better productivity and low operating costs. Geological conditions within the coal field are consistent with plans for ever greater outputs in the 1990s. Although much of the current production improvement is related to uprated machine capacity and simplified mines planning there is potential for even further development in the areas of maintenance, process control and engineering. Human resource development will also be a key factor. These programs are now well under way and Phalen Colliery is poised for top results in the 1990s. Comparison of the CBDC's top producer with similar operations elsewhere in the world, quantifies that potential.IntroductionAn exciting new mining project which has recently started production on Canada's East Coast has been conceived and designed to be one of the most modern and productive coal mining operations in North America.As with all mining operations, the business is basically that of material transportation. Daily, the product is transported many kilometres from the underground face to the surface and then to washing facilities. Men, materials and equipment are transported to and from the surface and the operating faces and services, such as electrical power, ventilating air, fresh water, discharge water, communications and compressed air are supplied throughout the operation to cover operating requirements. On all accounts the operation has been designed to take advantage of the latest proven technology."

Jan 1, 1990

By J. W. Smith, J. Van Dusen, A. Papachristodoulou

"As part of a study to evaluate factors affecting tankroom air quality, the mechanism of aerosol generation from bursting bubbles in electrowinning operations has been investigated. Typically 2 to 3 mg/m2.s are produced in zinc tankrooms. Analysis shows that the rate of production of film drops (geometric mean diameter - 2 urn] increases with decreasing bubble size, and that jet droplets (geometric mean diameter - 20 um) are not produced with gas bubble larger than - 4 mm. Both mechanisms of drop formation and current efficiency are affected by surface active agents, with an over-all reduction in emission of up to 60% to 70% being achievable. A source control system which does not adversely affect electrolyte properties is always preferred, and coalescence of all gas bubbles in to a continuous stream of gas at a single point on the electrolyte surface would eliminate aerosol emissions. This objective was the basis for design of a coalescence device which, in laboratory tests, reduced the emission rate by over 95%.The control device fit s over the electrodes in the electrowinning cell and is partially immersed in the electrolyte. A number of changes in the design which resulted in significant improvement in the performance of the device are reported.Field tests have shown that only about 75% of the aerosol below 10 um can be eliminated by coalescence. The remainder (up to 95% of the total) is controlled by coalescence of droplets, by impaction on the exposed collector surface and gravitational settling.The device does not interfere with operation of the tankroom, handles the effect of surges in power during harvesting, and is simple and inexpensive to maintain. IntroductionDuring the electrowinning of metals (such as zinc and copper) gases are evolved along the electrode surface forming small bubbles. The bubbles travel upwards and burst on the electrolyte free surface generating, in this way, small droplets. Because the electrolyte is often highly acidic or contains toxic materials, the whole process can result in the formation of an aerosol in the atmosphere above the electrowinning cells which poses a serious health hazard to workers in the area, and corrodes equipment."

Jan 1, 1988

By Fred E. Gray

The mill of Bralorne Mines, Limited, is located on the government highway in the Bridge River mining district of British Columbia, approximately fifty miles northeast of Shalalth, the shipping point on the P.G.E. railway. Prior to 1931, the property now owned by Bralorne Mines, Limited, was operated by Lorne Gold Mines, Limited. During the early operation of the mine, the ore had been treated at various times in one of three small amalgamation mills on the property. With the succession to ownership by the Bralorne Mines, Limited, work was started on construction of a new mill of approximately 100 tons capacity per day. The new mill was put into operation in the month of February, 1932, and since that date has been in continuous operation, milling an average of slightly over 3,000 tons of ore a month. The ore treated in the Bralorne mill is a gold-bearing quartz containing a very small amount of silver. About 75 to 80 per cent of the gold is in the form of free gold, the principal remaining portion being intimately associated with pyrite and arsenopyrite. The gangue rock is quartz, together with varying but relatively small amounts of altered diorite or albitite. In some of the ore, usually the higher grade portions, there is also considerable talc, which forms much slime in grinding. The mill is situated near the portal of the main haulage tunnel and the ore is received directly from the mine ore-trains, which dump on to the grizzly over the coarse-ore bin of the crushing plant. Figure 1 shows the flow-sheet of the mill as it is now being operated. Various changes have been made in the flow-sheet and in the reagents since the commencement of operations, and doubtless minor changes will continue to be made in order to increase the efficiency of the mill. Among the more important changes were those from two-stage to single-stage grinding, and from amalgamation plates to blankets. The change in the crushing was made because too much crushing was done when both primary and secondary mills were employed.

Jan 1, 1933

By Gordon E. Agar

"The effectiveness of two this compounds for copper sulphide depression in molybdenite flotation has been examined with batch bench scale tests.Both thioglycollate and trithiocarbonate proved to be good depressants producing results similar to those f or cyanide and hydrosulphide. Ferrocyanide was ineffective on the samplematerial tested.The depressing effect of thioglycollate was readily reversed by an addition of xanthate.IntroductionThe separation of molybdenite from copper sulphide minerals has been practised for a long time(1,2). The predominant scheme is to depress the copper sulphides while capitalizing on the ready floatability of molybdenite to effect the separation. There are many recipes for depressing the copper minerals(3), among them the addition of sodium cyanide, particularly if the copper is present primarily as chalcopyrite; some form of sulphide whether as sodium sulphide, sodium hydrosulphide or phosphorous pentasulphide when there is a mixture of copper sulphides such as bornite, chalcocite and chalcopyrite; potassium ferro cyanide may be used when chalcocite is the principal copper sulphide; peroxide or hypochlorite; as well as heating in the presence of lime. There are different mechanisms by which these reagent s depress the copper sulphides. Sodium cyanide and the sulphide-producing compounds apparently reduce the potential of the copper sulphides to the point where they ar e rendered unfloatable by xanthates . Another study(4) showed that after cyanide addition, chalcopyrite was rendered un floatabl e until the REDOX potential (measured with a gold electrode with a saturated calomel reference) had become more positive than -250 mY. If the chalcopyrite pulp was conditioned after the cyanide addition the REDOX potential increased slowly, whereas if air was introduced during the conditioning the potential r ose much more rapidly. The difference in time to reach the desired level of - 250 mV was as much as 20 minutes' 25 minutes being required when air was absent but less than 5 minutes when air was admitted . These observation s demonstrate some of the problems encountered when using cyanide to depress sulphides such as chalcopyrite . The system adjusts to counteract the depressing effect of the additive. To overcome this tendency it is necessary to either add an overdose at the beginning or to more or less continuously add the regulating reagent. In this study cyanide solution was added under automatic control to maintain a specified REDOX potential."

Jan 1, 1984

By J. C. Folinsbee, D. R. Derry

"The Property of Opemiska Copper Mines (Quebec) Ltd. is in Levy Township, Chibougamau district, west of Chibougamau and south of Opemiska Lake. The original find was made in 1929 by the late Leo Springer and associates of Prospectors Airways Ltd., following observation from the air of an area of dark rocks in newly burned-over country. Work on the ground discovered three veins of high-grade chalcopyrite in gabbro (No. l, No. 2, and ""North"") and, after several seasons of trenching and diamond drilling, financed by Ventures Ltd., a shaft was sunk in 1936. This work indicated about 280,000 tons of six per cent copper ore to a depth of 500 feet. During this period, the senior author carried out a reconnaissance geological survey over the whole property and surrounding claims, which showed that the veins were in the gabbro portion of a large composite basic sill that had been folded with the enclosing lavas. Owing to the low price of copper and lack of transport work was suspended and the property remained dormant until 1951.In that year the company was re-financed, the property prepared for production, and further exploratory drilling undertaken. The drilling, based on structural indications, located a new vein of which the only previous evidence had been some irregular stringers. This vein, No. 3, was traced by drilling for a length of 2,000 feet and the indicated reserves were thereby increased to about one million tons. An additional vein, No. 4, was intersected in several holes.With this encouragement, plans for production were confirmed, and operations commenced' at the beginning of 1954 on a scale of about 400 tons a day, concentrates being shipped by truck to St. Felicien and thence by rail to Noranda. In the first year of operation concentrates were re-covered carrying 14,047,210 pounds of copper, 76,714 ounces of silver, and 6,259 ounces of gold. The operation is under the direction of J. P. Millenbach, General Manager, with J. M. Thompson as Assistant General Manager and F. G. Cooke as General Superintendent on the property."

Jan 1, 1949

By Robert B. Parsons

"The annual onslaught of provincial budgets and tax changes is complete, and once again the Canadian taxpayer is being asked to dig deeper into his pocket to fund old and new programs. It is noteworthy that 1987 tax reform promised lower taxes, but a broader fax base. Five years later, we still have the broader tax base, but the lower faxes have gradually crept up to pre-tax reform levels. Surprise! Surprise!IntroductionThe last edition of Tax Notes commented on some important proposals announced in Manitoba's 1992 budget. In this issue, Tax Notes summarizes the 1992 budget proposals of British Columbia, Ontario and Quebec. These budgets reflect the continuing trend of transferring responsibilities and the related costs-from the federal government to the provinces. As well, the budget papers bear witness to the respective governments' political stripes. British Columbia, Ontario and Quebec are seeking higher tax revenues. Only Quebec continues to acknowledge the importance of the mining industry in its annual budget documents."

Jan 1, 1992

By D. Lauzon, H. de Ruiter

"In 1988a decision was taken to design and install a computerized mine monitoring and control system. This system had to monitor and control all pumping and ventilation underground. The operation of the mine air heating, using waste heat from the mine water and compressors, was to be part of the system. It ultimately also had to interface with the four existing Canadian General Electric Series 3 PLC's which controlled the No .3 shaft loading pockets. Beside operational control and trouble shooting, the system is a valuable tool in energy management and ultimate savings are estimated at $50,000 per year.The final equipment selection was a General Electric Series Six PLC on surface with a total of 17 Series One Plus and Juniors PLC located underground. Data is transferred through a two-pair shielded cable using modems. Both analog and digital functions are being utilized.The basic monitoring and control system was commissioned during 1989and, due to a higher level of technology today, further improvements have been planned for the future. The system was designed by Walter Dow together with Gordon Champion of D.G. Champion Engineering Ltd. of Toronto. Advice for the ventilation part of the project was obtained from Maurice White, Independent Ventilation Consultant.The Ministry of Energy, Mines and Resources and the Ministry of Energy of Ontario approved this project together with the waste heat recovery project to qualify for a grant of$135,000 under the Enerdemo-Canada program.IntroductionThe Macassa mine is a narrow vein gold mine situated about 2 km west of the town of Kirkland Lake in northeast Ontario. The mine has been in continuous operation since 1933 and a total of about 3.0 million ounces have been recovered out of 6.6 million tons of ore ."

Jan 1, 1991

By G. A. Davidson, P. G. Williams

"New developments in centrifugal slurry pump technology are discussed in relation to their importance for improving pump operation and reliability.Experimental data obtained by measuring the velocity of liquid flows in a slurry pump casing using Laser Doppler Velocimetry are presented. This demonstrates the importance of selecting pumps with the proper hydraulic design to provide optimum efficiency, maximum part life and minimum operating cost.The paper also discusses the use of new wear resistant materials, such as ceramic/metal composites, which can significantly improve the life of parts exposed to abrasive media. The results of laboratory attrition tests are presented. IntroductionCentrifugal slurry pumps are of primary importance for the hydro transport of abrasive and corrosive media in the mineral processing industry. As for all process equipment, slurry pumps must be carefully selected and operated to provide optimal performance. To achieve this, it is necessary to select equipment which will provide efficient and reliable operation for the specific service conditions and incorporates the best materials available to obtain maximum parts life.Abrasive wear of liquid end components is the most important aspect that distinguishes the design and application of slurry pumps from other types of pumps. It is therefore necessary to have a fundamental understanding of the mechanical interaction between pump components and the media being handled, as this will impact significantly on hydraulic design, mechanical reliability and selection of wear resistant materials. Recent advances in computational approaches'» have greatly improved the prediction of wear rates in pump casings by facilitating the solution of complex equations which describe the wear mechanisms mathematically. In conjunction with this, new experimental techniques allow researchers to measure flow fields in pump casings using non-invasive devices such as Laser Doppler velocimeters."

Jan 1, 1992

By I. I. Bethcherman

Introduction 1.-lmportance of Physical Nature of Condensates The metals of commercial interest which have reasonably high vapour pressures below 1,200° C. are mercury, cadmium, sodium, zinc, magnesium, lithium, and calcium. With the exception of mercury, these metals occupy high positions on the electrochemical series and form compounds with very high negative free-energies of formation. It is highly desirable that such metals should not be produced in a form which is finely divided, on account of their reactivity with atmospheric gases. Powders of magnesium, calcium, and even zinc (blue powder) are dangerous to handle and cannot be coalesced by simple melting techniques. Vaporization in vacuo forms a convenient method of handling and purifying the alkaline earth metals in particular and a previous paper by the authors dealt with some of the factors controlling the separation of metals by this technique (12). An essential part of the operation is the condensation of the vapour to produce a massive deposit which may be conveniently melted and handled by established metallurgical techniques. This investigation sought to determine the conditions affecting the nature of solid condensates.

Jan 1, 1951

By Sergio Romo, Gerardo Fuentes, Adriana Garcés

Refractory ores with gold entrapped in a sulfide matrix, must be processed in a first stage with chemical or physical treatment in order to liberate the gold for a subsequent step with cyanide. The goal of this research was to compare the refractory behavior of a gold concentrate treated using two pretreatment methods: pressure oxidation and fine grinding. Gold concentrate from Viacha Mining in Bolivia, assaying 50.11 gpt, with a P80 of 131 ?m was used. The concentrate contains arsenopyrite and pyrite as main sulphides in the matrix. A preliminary test with cyanide resulted only 13.5% of gold extraction with 4 hours of stirred leaching. Using an autoclave oxidation with sulphuric acid and 12 bar oxygen pressure at 220°C pretreatment, the cyanide gold extraction increased to 69.0% in 4 hours. When material was ground in a pulverizer, producing a P80 of 20 ?m and the product directly cyanided, stirred leaching gave a gold extraction of 65% in 4 hours. For both techniques, the effect of temperature, sulfur produced in autoclave oxidation, optimization of the cyanide and the nature of residues were also studied.

Jan 1, 2014