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By S. Nakamura, K. Fujiwara, S. Hirosawa, S. Tsukamoto, Y. Koshino, Y. Aruga

"In this study, hardness test, differential scanning calorimetry(DSC)and transmission electron micros copy were carried out to investigate the age-hardening behavior of Al-Mg-Si alloy with a Mg+Si concentration of 1.5mass%, and a Mg/Si ratio of 1.0. Pre-aging treatment was conducted for the solution-treated and then water-quenched specimen at 100, 80, 60, 40, 20 (natural aging), 0 and -20°C for 20min or 5h, followed by artificial aging at 170°C for 20min. It was found that when pre-aging time is prolonged from 20min to 5h, the bake-hardening response is deteriorated irrespective of the pre-aging temperature. In particular, the specimens subjected to pre-aging at 20-40°C for 5 h hardly increased the hardness with the subsequent artificial aging. From the results of DSC measurement, it was suggested that as pre-aging temperature is lowered, the amount of solute clusters formed during pre-aging, i.e. Mg-Si clusters and Si-rich clusters, is decreased, but the ratio of Si-rich clusters is increased, resulting in the deteriorated bake-hardening response.INTRODUCTIONIn recent years, Al-Mg-Si alloys have been widely used forautomotive body panels due to their excellent characteristics such as high strength-to-weight ratio and good formability. Their strength is increased not only by artificial aging during paint-bake treatment; i.e. “bake-hardening”, but also when kept at room temperature(RT);i.e. “natural aging”, in association with the suppressed bake-hardening response. Such a “negative effect of two-step aging” has been a serious problem because Al-Mg-Si alloy coils are unavoidably maintained at RT in the manufacturing process of body panels; e.g. shipping and storage. However, it was reported that pre-aging above 70°C before the two-step aging can restore the bake-hardening response, and such an improvement is related to the formation of solute clusters(Sato, 2006; Abidet al., 2010; Takaki et al., 2014; Zandbergen et al., 2015). From the comprehensive analysis by three-dimensional atom probe (Aruga et al., 2014 and 2015), it is believed that Mg-Si clusters formed during pre-aging transform into the strengtheningß"" phase, whereas Si-rich clusters formed during pre-aging act as a detrimental precursor of ß""phase. In this study, it was aimed to investigate the effect of pre-aging conditions, especially pre-aging temperature and time, on the formation of solute clusters during pre-aging, in order to elucidate the mechanism of the age-hardening behavior of an Al-Mg-Si alloy."

Jan 1, 2018

By F. W. Wellmer

"This paper discusses the changing nature of reserve/consumption ratios, using data from Canadian operations and focussing particularly on copper.IntroductionStudies in world metal consumption and world metal reserves are done regularly by the U.S. Bureau of Mines, the German Federal Institute of Geosciences and Raw Materials, and other institutions. Formerly, on the basis of these data, the following figures were calculated:• a static lifetime of reserves-reserves at year end divided by the consumption of the previous year;• a semidynamic lifetime of reserves-reserves at year assumed constant growth rate.These figures were severely criticized because they were purely theoretical and did not consider the availability of the raw materials.Recent practice is to calculate reserve/consumption ratios (R/C ratios) for periods(1) or for different years(2,3) and to interpret the trend. For base metals, these R/C ratios are increasing (Table 1). This had led to the conclusion that today the relative availability of base metal reserves has increased as compared to 10 or 15 years ago(4,5) As there are normally numerous deposits for each commodity, the anticipated production rates of deposits are irrelevant to this conclusion as long as the statistical distribution of possible production rates does not change significantly.The above conclusion is only justified if the quality and the nature of the data base remain the same. This is certainly the case for the consumption data. It is also assumed for the quality of the reserve figures, which usually take into account only proven and probable reserves. For the nature of the reserve figures, however, this does not seem to be true.Undoubtedly, the reserves increased in absolute terms between 1966 and 1978. To put the absolute reserve figures into perspective, it is common, as said above, to compare them with the mine production, which increased in the free world between 1966 and 1978; e.g. for copper by 40%, for Pb by 17% and for zinc by 36%. However, the reserves are also influenced by other factors, such as average size of the mines, changes in the grade of the mined ore, price-to-cost relationships and the like.The purpose of this paper is to examine the nature of the reserve figures in more detail. Because the completeness of mining data published in Canada is rather exceptional, Canadian .data serve as an example and it is assumed that the conclusions can be extrapolated to other mining countries or at least to those with free market systems."

Jan 1, 1981

By Takao Oishi, Go Ohara, Toru Kitazaki, Masahiro Tanaka

"The High Pressure Acid Leach (HPAL) plant for nickel-cobalt mixed sulphide production at Coral Bay Nickel Corporation (CBNC) in the Philippines has been in operation since 2005 with a capacity of 10,000 t/year of nickel. Subsequent to the commissioning of the second plant in 2008, the production capacity increased to 22,000 t/year of nickel (Llerin et al., 2011). CBNC’s annual nickel production reached more than 24,000 tons of nickel in 2014. The concepts to achieve this capacity are the high availability and the reciprocally flexible operation of both plants. The availability depends on some factors, such as the control of impurities in the process and the equipment condition, to mention a few. In the HPAL process, it is not only the autoclave operating conditions that affect nickel extraction but also the impurities in the ore greatly influence it. The major element in the ore is iron and most of this iron is precipitated as Fe2O3, while the rest remains as Fe2+ or Fe3+ sulphate in solution. These ions in solution reduce the availability, so it is important to control the formation of iron ions by controlling the impurities in feed ore as well as the HPAL conditions. This paper presents the general HPAL process and the behaviour of impurities, focusing on iron behaviour in the HPAL process.INTRODUCTIONCoral Bay Nickel Corporation ProfileCoral Bay Nickel Corporation (CBNC) was founded on April 2002, as a joint venture of four companies; namely, Mitsui Corporation (18%), Sojitz Corporation (18%), Nickel Asia Corporation (10%) and Sumitomo Metal Mining Corporation (SMM) with a controlling stake of 54%. Aside from its capital share, Nickel Asia Corporation also supplies the ore and limestone for the High Pressure Acid Leach (HPAL) plant located in Rio Tuba, Philippines, as shown in Figure 1 (Tsuchida, 2008). The objective of the CBNC project is to produce 22,000 t/year (original design) of nickel and 1,500 t/year of cobalt, as sulphide, by the treatment of nickel laterite ore which is a low grade nickel oxide ore in the Philippines (Mines and Geosciences Bureau, 2014). The sulphide product has been exported as a raw material to the SMM Nickel Refinery in Japan for 30 years. The product of this plant, a mixed (Ni/Co) sulphide, is shipped to the SMM’s Nickel Refinery in Niihama, Japan. SMM Corporation provides the technology and management personnel to the plant. SMM Corporation also supplies the sulphuric acid, which is the main reagent for the HPAL process."

Jan 1, 2016

By Ata Akcil, Z. B. Karshigina, Ye. G. Bochevskaya, Z. S. Abisheva

"Phosphorus slag is the most heavy-tonnage waste of yellow phosphorus production, which is stored in the dump fields for many years creating ecological problems in the regions. Despite of the actions taken to utilize the slags, most of them remain in the slag disposal area. One of the relevant and priority directions is rare-earth metals production (REMs), presence of which in the phosphorus slags allows considering the latter as an acceptable raw material source. Phosphorus slags contain about 30–40 wt% of silicon dioxide, therefore they can serve as a source of production of precipitated silicon dioxide highly required in different industries.The purpose of this work is the most complete REMs recovery in the solution while leaching and subsequent processing of siliceous cake. The work shows results of researches on establishment of the chemical and phase compositions of phosphorus slags, determination of the forms of presence therein of REMs compounds, processes of phosphorus slag leaching by nitric acid and processing of produced siliceous cake by NaOH solution.Based on the data of the instrumental and chemical methods of phosphorus slag analysis, it was established that it consists of pseudowollastonite a-CaSiO3 for 90–92%. It was found out that REMs are present in it in the form of carbonate apatite Ca10(PO4)6CO3 or rare earth apatite, and La2S3 compound inclusions.Optimum parameters of phosphorus slag leaching process were selected: HNO3 concentration 7- 7.5 mol/L; L/S ratio = 2.6–3 mL/g; temperature – 50–80o?; duration – 1 h; pulp stirring – 500 rpm. Recovery of SREMs, CaO, Al2O3 and Fe2O3 into the solution were achieved at 98.0, 99.1, 99.0 and 18.8%, respectively. Presence of 10 elements of the rare earths group in the phosphorus slag was established. It was found out that recovery of almost all REMs is within ~92–99%, except for Sc and Lu – ~39% and ~28%, respectively.For the purpose of optimization of siliceous cake leaching by NaOH solution, influence of some physical and chemical parameters was studied: N?O? concentration, L/S ratio, temperature, and duration. Results of the experimental data will serve as a basis for development of the technology of complex processing of the technological waste of phosphorus industry with production of REMs concentrate and precipitated silicon dioxide."

Jan 1, 2016

By A. Singh

Deformation structures after tensile and compression tests on Mg926Zn64Y alloy extruded at 250°C and 400°C are studied, in as-extruded and heat treated conditions. The icosahedral phase particles stimulate recrystallization during extrusion, resulting in fine grain size. Tensile and compression tests at room temperature show comparable yield strength, with a yield asymmetry ratio up to 0.98. c-type dislocations are observed in the grains near the submicron size icosahedral phase particles. The source of these dislocations is believed to be dissociation of <c+a> type non-basal dislocations. No dislocation pile-ups on icosahedral phase particles are found. {10 1 2} type twinning occurs in compression.

Jan 1, 2006

By Shae K. Kim

The aim of this study is to manufacture magnesium alloys with alkaline earth metal oxides (BeO, CaO, MgO or SrO) additions with the objectives of (1) ensuring safety during processing and applications by raising the ignition temperature and reducing oxidation, (2) protecting the environment by reducing or eliminating use of protective gases, (3) maintaining or improving elevated temperature properties with lower amount of Ca or Sr or rare earth metals when compared with conventionally developed high-temperature magnesium alloys, (4) developing cleaner strip casting and continuous casting processes without hot tearing and (5) obtaining all of these objectives without sacrificing mechanical properties or increasing the cost of magnesium alloys.

Jan 1, 2006

By M. Azzaz

In this paper, we report on new mechanical tests, at high temperatures, performed with a supposed better aluminium nitride (A1N) material, containing fewer oxygen. Our purpose was twofold: (i) check whether creep resistance is modified and hopefully enhanced and (ii) determine the elementary mechanisms controlling plastic deformation through transmission electron microscopy (TEM) observations of deformed samples up 10% strain in compression at elevated temperatures (1823-1923 K) under constant stress in the range 150¬250 MPa. Stationary rates are lower by an order magnitude than those previously measured in MN with higher oxygen content. All dislocations imaged by TEM look undissociated, which clearly relates the formerly observed wide dissociation to oxygen in excess.

Jan 1, 2004

By Fathi Habashi

Teaching mining, metallurgy, and geology preceded that of the other engineering disciplines. The first School of Mines was founded in 1756 in Potosi (Fig. 1) in New Spain (now Bolivia), 38 years before the first Polytechnic School (École Polytechnique) was founded in Paris. The schools of mines were also pioneers in the teaching of chem- istry. The teaching staff at these schools cre- ated the basic literature on metallurgy, mining, and geology. They analyzed and dis- covered numerous minerals and discovered the metals tungsten, beryllium, chromium, uranium, zirconium, vanadium, indium, and germanium. The history of some of the first schools is given together with biographies of some of their distinguished teaching staff.

Nov 1, 1997

By D. P. Fenton

The Phelps Dodge El Paso Rod Mill produces approximately 2.4 million pounds per day of copper rod from a casting and rolling operation. The newly formed rod is treated to remove mill scale and oxides using a sulfuric acid and hydrogen peroxide solution which is bled periodically when the copper concentration reaches 30-35 g/L. The bleed solution is heated to 75° C to destroy the residual peroxide. Copper is then recovered in a 270 cell EMEW electrowinning plant. Clean acid is also regenerated in the EMEW plant and is returned to the rod cleaning circuit. The EMEW plant commissioned in January 2006, has two operators and replaces a copper sulfate plant with fourteen operators. The EMEW plant has a capacity of 1700 kg/day of cathode copper at 2.1 kWh/kg copper deposited. The electrowinning plant operates in closed circuit with the rod mill returning up to 2600 kg/day of sulfuric acid resulting in zero discharge. Use of dimensionally stable anodes (DSA®) ensures that the acid quality is maintained in the closed loop operation. The operating conditions, performance and plant experience of the EMEW copper and acid recovery plant are discussed.

Jan 1, 2007

THIS article describes the origin and details of a hydraulically operated switch to control the operation of an automatic underground pumping system. This system was installed in December, 1939, on the 2,350-foot level at No. 5 shaft of the Buffalo Ankerite mine. The pumping unit consists of an 8-stage centrifugal pump direct-connected to a 150 h .p., 2,200 volt motor. Pumping capacity is 200 gallons per minute under a 1,315-foot head and with a flooded suction. The control consists of a 200 amp., 2,200 volt oil-immersed starter with thermal overload protection, thermal protection on the pump, and a flow switch that is bypassed for 30 seconds after the pump starts. The 30-second time lag is operated by a relay mounted on the panel. There is a swing check valve in the discharge line of the pump which originally operated the flow switch by means of a connected outside lever which closed the switch as the check valve opened.

Jan 1, 1945

By William Petruk

Mineralogical investigations in connection with gold metallurgy are usually performed to find the reason for poor recoveries by cyanidation or by other leaching techniques. Poor recoveries most commonly are obtained when (I) native gold is encapsulated in an insoluble mineral as "invisible gold"; (2) native gold is coated with a precipitate; (3) gold-bearing products are insoluble in cyanide solutions; (4) carbonaceous material in the ore adsorbs gold; and (5) associated minerals decompose and consume cyanide. Samples of refractory material quite often have low gold tenors. It is difficult to find the gold-bearing minerals in such samples with an optical microscope because the probability of finding trace minerals in samples is small. The probability decreases with decreasing grain size of the gold-bearing mineral and with decreas¬ing gold tenor of the sample. Techniques have been developed to increase the success rate of finding gold grains; some are (1) concentrating heavy minerals; (2) preparing special polished sections; (3) searching with an image analyzer; and (4) dissolving associate silicate and sulphide minerals.

Jan 1, 1989

By N. Schmitt, E. Blond, F. Hild

Working linings of steel ladles progressively damage during the steel manufacturing process due to both severe thermomechanical and chemical stresses. In the framework of the coupling scheme proposed by Blond et al. (1), this study examines the effects of the thermomechanical loading on the onset of microcracking by considering that the complex microstructure of the slag-impregnated brick is fixed during the steelmaking process. The behaviour of the refractory is identified by using thermoelastic-(asymmetric)viscoplastic constitutive equations. Numerical simulations of a simplified geometry of the lining subjected to cyclic thermal loadings at the inner side are shown. Two cases are analysed, namely, i) the material is a homogeneous continuum with a thermoelastic-(asymmetric)viscoplastic behaviour, ii) the material is porous and saturated by liquid slag, and the skeleton has the previous non-linear behaviour. The stress and strain fields are shown, and for the porous medium the interstitial pressure of slag as well. Comparisons between these assumptions are made to assess the role of slag on the degradation of the working lining.

Jan 1, 2004

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 G. Vibert Douglas

THE prospecter and geologist in the field, in the search for gold, are very often faced with a real difficulty. The: mineralized rock _frequently contains gold which is so finely divided or associated with sulphides that it is not recognizable in the gold pan. In recent years, the practice has been to take samples, send them to an assay office, and sit down and wait for results. This paper describes a method of solving the difficulty of proving the presence of this fine gold. The investigation is still in an experimental stage; but certain results have been obtained which would seem to justify publication. We do not consider that the method outlined is quantitative, but we believe that qualitative results are assured. The procedure has the great merit of simplicity. A sample of approximately two pounds of the mineralized rock should be taken and powdered as fine as is practicable. This powder is theo panned and the heavy minerals concentrated. Approximately two grams of these concentrates are taken for the test (one gram can be roughly gauged in the field by heaping up the powder on a Canadian twenty-five cent piece). The material is placed in a test-tube and 6 c.c. of a 10 per cent solution of iodine in alcohol are added (one-third of a test-tube full is approximately equal to 6 c.c.). Heat gently for about ten minutes over a spirit lamp, but without actual boiling. Allow to stand undisturbed until the sediment has settled to the bottom. Remove the clear iodine solution with an eye dropper. Allow it to fall, drop after drop, on a warmed pyrex watch-glass (the drops should be of equal size), taking care that the successive drops fall in the same place and that each drop evaporates before the next drop falls. Heat is applied to the lower side of the watch-glass by means of a spirit lamp. If gold is present in amounts of $2.00 or more per ton, a gold mirror will be formed on the watch-glass. This process of dropping and evaporating should be continued until no clear solution remains. If no mirror has appeared when all the solution has been used, another 6 c.c. of the iodine solution should be added to the powder and the process repeated. The absence of a mirror after the double treatment denotes an amount of gold less than two dollars per ton at the present price, or that the ore contains no gold. The mirror obtained must be washed with nitric acid ( 1: 1) to remove any copper, silver, lead, zinc, and iron. The yellow mirror remaining is pure gold.

Jan 1, 1937

By D. F. Sherwin

"THE AREA which is described in this paper (Fig. 1) includes the continental margin of eastern Canada extending from the Gulf of Maine to the north edge of the Grand Banks, which, including the continental shelf, slope and rise, comprises an area of about 600,000 square miles. The paper is intended to give a background of the geological setting of this region in the context of its ultimate potential for oil and gas reserves in close proximity to the Nova Scotia energy market.HISTORY OF EXPLORATIONThe history of geological exploration of this area really began in 1878, when U.S. fishing boats brought back samples of rock recovered in trawls from their expeditions to the long-famous fishing banks off Canada's East Coast. Tertiary and Cretaceous fossils recovered from these samples indicated that the eastern Canadian continental shelf was actually the submerged northern extension of the Atlantic Coastal Plain."

Jan 1, 1972

By Niels Verbaan, Ron Molnar, David Dreisinger

"An acidic chloride leach solution was generated from the treatment of an ore containing the following value elements: silver, gold, indium, gallium, copper, zinc and lead. Iron was also co-extracted into solution as a ferric chloride species. Iron extraction was a significant component of the overall acid consumption of the leaching process. The recovery of iron by solvent extraction and water stripping was investigated. Tri-butyl-phosphate (TBP) was very effective at recovering iron from the leachate. The water strip solution could be decomposed to produce ferric oxide (hematite) and hydrochloric acid for recycle via hydrothermal hydrolysis or pyrohydrolysis.INTRODUCTION The Malku Khota deposit is situated in the eastern part of the Bolivian Altiplano at elevations between approximately 3,800 and 4,580 meters above sea level (Figure 1). The project is located 98 km east-southeast of Oruro, and 85 km south of Cochabamba in a relatively remote area."

Jan 1, 2016

By F. R. Archibald

IN a recent paper on Roasting of Beattie Concentrate (1), the importance of controlling the temperature, and the sulphur dioxide concentration was pointed out. It is the purpose of the present paper to present further information by which the most satisfactory conditions for roasting are more specifically defined. Incidentally, a method of illustration is developed for representing roasting curves on a three-dimensional diagram. The primary purpose of this investigation, as in the case of the earlier work, was the search for information that would be of practical value in improving plant operation and gold recovery. For this reason, emphasis is laid on the regulation of essential variables and on definition of their optimum values and limits for maximum gold recovery in the subsequent cyanidation process. Good roasting is considered at least as much an art as it is a science, and, in this light, theoretical consideration of the nature and sequence of the chemical reactions involved is of secondary importance. The presentation which follows includes a series of graphical illustrations, an interpretation of the graphs, some theoretical considerations, and a description of laboratory technique.

Jan 1, 1940

By K. Yoo

Chalcopyrite is the most abundant copper sulfide mineral, which is normally processed using pyrometallurgical methods (i.e., smelting) to produce copper metal. Smelting has several major disadvantages, such as high gas-handling costs, high capital costs, saturation of sulfuric acid market, and inability to treat low-grade concentrates and to recover some by-products, such as zinc, nickel and cobalt. The development of hydrometallurgical processes for chalcopyrite is desirable to overcome the problems of smelting. Because chalcopyrite is refractory, the leaching rate for chalcopyrite is very low. Therefore, increasing the leaching rate has been extensively investigated, both in sulfate and chloride media, as well as in the presence of bacteria. Chloride leaching processes have shown relatively high leaching rates. The mechanism of the chloride leaching process has been investigated, but the behavior of chalcopyrite leaching in chloride solution is not clear. Therefore, the effect of the solution redox potential on the leaching rate of chalcopyrite in chloride solution was investigated. In the present study, leaching experiments were carried out using 0.1 M chloride solutions and the results indicate that high leaching rates of chalcopyrite can be achieved at relatively low solution redox potentials.

Jan 1, 2007

By J. E. Gill, A. R. Byers

"The property of Sladen Malartic Mines, Limited, is in the northern half of Fourniere township, Abitibi county, Quebec. The group is large, but the part so far found to be of economic interest is a strip 3,200 feet long between the Canadian Malartic property to the west and the East Malartic and National Malartic properties to the east ( Fig. 1).The original claims were staked in 1923 and 1924 by St. B. Sladen and H. S. Kennedy because gold was known to occur on claims nearby. In 1928, detailed mapping of the Malartic Gold Mines property (now Canadian Malartic) showed the presence of an east-west gold-bearing zone traceable almost to the Sladen boundary. During the winter of 1929, a hand-driven drill was used to secure short sections of core through casing pipe sunk to bed-rock. This proved the existence of the main Sladen ore zone, but it was not until the price of gold was increased, in 1934, that serious work was attempted.Underground work was started in 1935 and milling in January, 1938. To the end of 1945, 168,882 oz. of gold were recovered from 1,641,974 tons of ore, an average of 0.103 oz. a ton.GEOLOGYThe bed-rock underlying' the Sladen Malartic property consists mainly of Precambrian greywacke and volcanics that appear to form a conformable series with a general northwest strike and vertical to steep northerly dip. Except where disturbed locally by drag folds or faults, tops face north. Intrusive rocks that range in composition from diorite to granite cut the sediments and volcanics. The basic types, generally quartz diorite and diorite, form dykes or sills in the volcanic rocks. The more acidic types, mainly quartz syenite and related porphyries, intrude the volcanics and the sediments in the form of dykes, sills, and larger, stock-like bodies.The orebodies are parts of slightly shattered or brecciated zones, mainly in greywacke, but partly in syenite, diorite, and volcanics, that have been more or less replaced by fine-grained quartz, pyrite, and minor amounts of sphalerite, galena, sylvanite, petzite, and gold."

Jan 1, 1954

By N. E. Chaouai, M. Lavigne

"Indicator kriging is one of the non-parametric geostatistical techniques, ideal for estimating the reserves of irregular mineralizations (e.g. gold, uranium, platinum, diamonds, etc.). Such mineralizations are characterized by variograms which are very sensitive to extreme values (outliers) and very difficult to model.The classical approach to this problem in the industry is to trim off these high grades using arbitrary empirical upper limits established either from practice or subjectively. Contrary to this simplistic approach, indicator kriging discretizes the histogram of the grades (usually log normal) in several classes and carries out interpolation separately for each class. This paper gives an overview of the differences between ordinary and indicator kriging along with the steps required to carry out indicator kriging. The paper concludes with a case study involving a gold deposit estimation.IntroductionParametric geostatistics (ordinary kriging) has given us satisfactory results over the years in estimating the reserves of well behaved deposits with coefficients of variation close to 1 (e.g. sedimentary and porphyry type deposits). However, numerous problems have been encountered in estimating irregular mineralizations (e.g. small vein deposits of precious metals) with high coefficients of variation in the range of 2 to 5. Such deposits are characterized by a very small proportion of extreme values (outliers) which create distortions on the variograms (pure nugget effect) and render them useless(1,2).The solution often followed by the mining industry today is to trim off these values based on empirical limits. These limits are derived either by comparison with production results (or bulk samples) or by geological interpretations. Needless to say that such manipulations can lead to serious errors in estimating ore reserves (usually underestimation of total metal quantity), especially when production results or bulk samples are absent.On the other hand, the solution followed by the geostatisticians in the past was to smooth out the data using transforms (e.g. normal-score or natural logarithms). Such transforms are nonlinear and they required non-linear estimation techniques such as disjunctive kriging (DK) or multivariate gaussian kriging (MG) which require normal related hypotheses, not necessarily true in geology.Nonparametric geostatistics (indicator and probability kriging) have been -developed in order to handle these problems related to highly skewed distributions."

Jan 1, 1990