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By P. Lostritto, G. E. Agar, G. Labonte, M. Cherevaty

"A locked cycle flotation test was done on a sample from the ovoid portion of the Voisey 's Bay copper-nickel sulphide ore. The chemical conditions for this test were generated by prior independent testing. In this test work the time in each of the five separation stages was optimized prior to executing the locked cycle test. A numerical simulation of the continuous circuit material balance was done prior to the locked cycle test. The test results were not fully satisfactory because the flotation of pyrrhotite in the bulk rougher and cleaner stages was not consistent. The preliminary indication was that the samples had oxidized to varying degrees during storage.INTRODUCTIONINCO has performed batch laboratory flotation testing on ore from Voisey's Bay which is a mixture of chalcopyrite, pentlandite and pyrrhotite. Earlier, Lakefield Research was contracted by Diamond Field Resources to test the ""flotability"" of the ore, which included a pilot plant trial. INCO's J. Roy Gordon Research Laboratory has repeated many of the batch tests that Lakefield did to verify their results. Based on their own work, INCO has modified the circuit proposed by Lakefield Research. The modified circuit is based on batch test work, but no locked cycle test (LCT) was done. It is believed that this circuit will produce a copper concentrate at 29-30% copper and a primary nickel concentrate at 15-20% with recoveries of 80% or above.For several years the University of Toronto has been working with INCO to provide ""hands on"" experience for undergraduate students as an Industrial Research Project (IRP). This year, the objective for IRP was to optimize the time for each of the five separation stages for the Voisey's Bay ore then to numerically and experimentally simulate the material balance for a continuous circuit."

Jan 1, 1998

By W G. Brese

The attention of the world is being focused on the spectacular rise of elemental sulphur production in Alberta. In the short space of a decade, production has increased from less than 10,000 long tons, in 1952, to al-most 1,000,000 long tons in 1962. Moreover, 1963 sulphur production is expected to rise by 50 per cent to approximately 1,500,000 long tons, and further increases are forecast for ensuing years. The reason for this dramatic in-crease in elemental sulphur production, particularly in the last year or two, is that Alberta elemental sulphur is recovered in association with the production of sour natural gas. When very large volumes of natural gas began moving to U.S. markets in the latter part of 1961, the resultant increase in sour gas production led to a marked increase in the production of sulphur. Consequently, Canada, mainly on the strength of sulphur produced in Alberta, will soon become the second largest producer of sulphur in the Free World

Jan 1, 1963

By Michael T. McCaffrey

The wide range of potential feed materials, process steps, and products in metallurgical facilities means that standard equipment might not be available to adequately meet the project technical and economic needs. Custom designed equipment should be considered only after rigorous research precludes purchasing standard equipment. However, the decision to use custom equipment introduces a new element of risk into the project. To manage the risk, custom equipment design should be developed through the same front end loading (FEL) phases as project development. If more than incremental development of custom equipment is required, appropriate test work or pilot trials are required to test key uncertainties. Important activities during custom equipment design include maintaining clearly defined performance objectives, conducting appropriate reviews, carefully crafting commercial and intellectual property agreements with design and fabrication partners, and assembling a multidisciplinary team with sufficient development expertise.

Jan 1, 2015

By Luis Bergh, Juan Olivares, Juan Durán, Juan Yianatos

"In the last decades heuristic approaches based on logic rules have been one favored tool to control flotation units and plants on top of distributed control systems. Fundamental knowledge on flotation processes, expressed in reliable models, and programs to assure the quality of the information, contained in available measurements, are still insufficient to develop robust predictive control strategies. In this paper the idea of using simplified models, when a known disturbance is coming into the process, is explored. As a first approach, the set points of the froth depth and air flow rate controllers are estimated based on this model. Since these target predictions are only approximate, a conventional feedback expert system, based on logic rules, continues the task of calculating the set points of the distributed controllers, in order to decrease the gap between actual and desirable metallurgical targets. This combined actions permitted a fast response of the process to change the operation of the circuit when a measured disturbance is detected. This control system was implemented and experimentally evaluated in a pilot rougher flotation circuit, with three pneumatic cells, with froth depth and air flow rate controllers in each cell. Since the circuit is operated for the air-water system, a phenomenological model, with parameters estimated from industrial data, is fed on-line with real operating variables and virtual values, characterizing the feed (grades, solids%, particle size distribution), in order to predict the metallurgical targets (recovery and concentrate grade). Several cases are discussed showing the benefits of this control system and the possible improvements to work on. INTRODUCTIONToday, large size mechanical flotation cells of 100 to 300 m3 are used in rougher operation in different flotation industrial plants, in Chile and worldwide. However, in spite of the advances in fundamental research and the notable growing in equipment size, with more complete instrumentation systems, there are still a lack of reliable data for industrial flotation modeling and simulation to advance in better control systems design."

Jan 1, 2016

By G. H. Gale, M. A. F. Fedikow, L. B. Dabek

Rare earth element (REE) data are reported for ores, sul?de-bearing rocks and host rocks from massive sul?de deposits and barren sul?de facies iron formations in Proterozoic volcanic rocks of the Flin Flon-Snow Lake area, Manitoba. Some of the rare earth elements (e.g., Eu), are selectively leached in zones of intense alteration and redeposited together with the sul?des and silicatesin the uppermost parts of the alteration zones and at the rock-water interface. Chondrite normalized REE pro?les of layered sul?de ores and exhalites proximal to the deposits typically have positive europium anomalies and are enriched in light REE. In contrast, barren sul?de facies iron formations exhibit negative or ‘normal’ Eu pro?les. REE data are useful to explorationists in determining the presence of ‘off-hole’ metal-bearing sul?de zones, in distinguishing metal-poor sul?dic layers related to ‘economic’ hydrothermal activity from barren sul?de facies iron formation and in some instances as a means of establishing ‘ore-equivalent’ strata.

Jan 1, 1997

By G. H. Gale, M. A. F. Fedikow, L. B. Dabek

Abstract-Rare earth element (REE) data are reported for ores, sulfide-bearing rocks and host rocks from massive sulfide deposits and barren sulfide facies iron formations in Proterozoic volcanic rocks of the Flin Flon-Snow Lake area, Manitoba. Some of the rare earth elements (e.g., Eu), are selectively leached in zones of intense alteration and redeposited together with the sulfides and silicates in the uppermost parts of the alteration zones and at the rock-water interface. Chondrite normalized REE profiles of layered sulfide ores and exhalites proximal to the deposits typically have positive europium anomalies and are enriched in light REE. In contrast, barren sulfide facies iron formations exhibit negative or ‘normal’ Eu profiles. REE data are useful to explorationists in determining the presence of ‘off-hole’ metal-bearing sulfide zones, in distinguishing metal-poor sulfidic layers related to ‘economic’ hydrothermal activity from barren sulfide facies iron formation and in some instances as a means of establishing ‘ore-equivalent’ strata.

Jan 1, 1997

By A. R. Kinkel JR.

"The Buffalo Ankerite mine is in the southern part of the Porcupine gold district of northern Ontario. The mine has a history of exploration and development reaching back to 1911, and has been operated continuously since 1932. From 1932 to 1942 a total of 510,874 oz. gold was produced from the mine. In 1941 the production was 71,654 oz. from 448,621 tons of ore.With few exceptions, the ore-bearing veins did not crop out. They were discovered during the prospecting of the prominent outcrops of barren or low-grade quartz-carbonate breccia near the veins.GEOLOGICAL SETTINGThe Porcupine gold district lies in an area of folded and sheared Precambrian lavas, sediments, and intrusives. The Buffalo Ankerite mine is in the southern part of a large fold. The structure appears to be a continuation of the Vipond cross anticline and accompanying syncline described in earlier papers (1, 2). The orebodies lie along both flanks of the synclinal part of the fold, and are known as the north and south vein systems, respectively. No mineable veins have been found on the axis of the syncline (Fig. 1).The rocks found in the mine area are pillow lava, dacite, conglomerate, quartz porphyry, tuff, and fragmental lava. The tuff and fragmental lava are now largely altered to chlorite schist. Productive veins have been found only in pillow lava, dacite, and conglomerate, but a minor amount of gold occurs in some of the quartz porphyry. The Porcupine Creek fault, a zone of intense shearing over 1,000 feet in width, lies immediately south of the mine. A spur fault branches to the northwest from the Porcupine Creek fault, separating the north from the south vein systems ( Fig. 1) ."

Jan 1, 1954

By Thomas H. Heine

"The Rabbit Lake uranium deposit is located at 58° 11’00”N.. 103°42'36""W., close to the west side of Wollaston Lake, and approximately 800 km north of Saskatoon. The orebody is hosted by Aphebian Wollaston Group rocks, initially deposited as a series of shallow-water marine sediments consisting, in part, of carbonates and possible saliferous petites. Metamorphism during the Hudsonian Orogeny, peaking at about 1850 Ma, recrystallized the sediments to upper amphibolite grade paragneisses. This was accompanied by partial anatexis. The waning stages of Hudsonian orogenesis appear to be marked by minor granitic intrusive activity.The post-Hudsonian period was marked by a long interval of physical and chemical erosion, resulting in the unroofing of the Wollaston metamorphic complex. The entire region underwent extensive lateritic weathering under tropical to subtropical conditions. Carbonates were especially vulnerable and, in the Rabbit Lake area, suffered extensive solutioning with accompanying formation of collapse breccias. Old zones of weakness also underwent periodic reactivation.It was during this period that uranium was leached from the surrounding meta-sediments by oxidizing meteoric waters, and transported into the karsted and fractured rocks of the Rabbit Lake doline.Athabasca Group sediments eventually covered the deposit, their diagenesis taking place at about 200 °C and 900 bars. This allowed the partial to complete recrystallization of the initial mineralization, resulting in a minimum age of 1281 ± 11 Major ""first""-generation pitchblende. Periodic fault/fracture reactivation modified the hydrologic regime within the deposit, resulting in episodic mobilization and recrystallization of pitchblende and other uraniferous species. This is clearly shown in the open pit at the present time: uranium is being mobilized and recrystallized on damp pit walls as bayleyite and liebigite due to the modification of the hydrologic system by mining activities.The uranium mineralization occurs mainly as fracture fillings, coatings, and impregnations within breccia zones and intensely altered metasediments. Lesser mineralization is intimately associated with phyllosilicates which form the matrix of a carbonate-col/apse mega-breccia. The primary ore mineral is pitchblende, consisting of five generations, and from which a large suite of secondary uraniferous minerals have formed. On a gross scale the metal content of this deposit appears to be simple, consisting almost exclusively of U, but minor Ni, As, Cu, Se, Fe and Co are also present. The eastern limit of the mineralization is defined by a vertically-dipping microgranite dyke - breccia complex, containing high-grade uranium values. The orebody is truncated to the west and at depth by the Rabbit Lake reverse fault. Minor mineralization occurs as fracture fillings in unaltered plagioclasite in the footwall of the ore body. Precipitation of uranium from solution could have taken place by a number of processes. A mobile reductant (methane, carbon dioxide, etc.) may have been generated from graphite present in some of the host rocks of the orebody. Sulphides are also a common accessory and may have aided in the formation of a reducing environment. Phyllosilicates may have acted as adsorbants for uranium, allowing for its fixation. This metal has also been incorporated into the phyllosilicates themselves."

Jan 1, 1986

By M. Härting, D. T. Britton, M. Nzikou Mamboukou

"Copper containing different types of nanocomposites have been characterized for nanolabelling and ID. Three types of the rare earth nanoparticles were used for this study, the oxide and the sulphur compound of the Eu and Tb. Characterization techniques uses SEM, and Raman for morphology, chemical composition, and optical characterization respectively. It has been shown that it is possible to include the rare earth particle in a copper matrix without damaging its physical properties. INTRODUCTIONThe development of new materials, often involves the addition of new properties without changing the beneficial properties of the original material (Chen et al., 2009; Khana et al., 2007; Patil et al., 2008). Nanocomposites are nanostructured materials, whose structural elements including clusters, crystallites or molecules, of dimensions ranging between 1 to 100 nm (Moriarty, 2001), or a composite material where one of the phases is a one, two or three dimensionally nanostructured material (Nanotechnology, 2006; Wang, 2001). Nanocomposite materials research is a fast growing area due to the high demand for materials for specialized applications (Edelstein & Cammarata, 1998), such as biolabelling, magnetic storage media, solar energy transformation (Jisen et al., 2004), and resistance welding applications (Bessergenev et al., 1997; Kwon et al.,2006).The properties of the nanocomposite materials depend not only on the properties of their individual parent materials, but also on their morphology and the interfacial characteristics. Thus, significant efforts have been focused on the control of the nanoscale structures via innovative synthesis approaches. Therefore, novel materials of unique properties may be obtained by combining properties from the parent constituents into a single material (Balan, 2006; Garcia et al., 2009). Possible effects of nanocomposites in the original material may include changes in the mechanical properties such as hardness , wear resistance (Rafaja et al., 1987), and electrical properties (Britton et al., 2003). The inclusion process may therefore be used to tailor materials to have particular mechanical, electrical and optical properties (Das et al., 2009). However, to fully understand the nanocomposite, it is necessary to study the fundamental properties of both the host matrix and the inclusions (Li, 2008)."

Jan 1, 2012

By Mayumi Ito

Mineral processing of rare-earth ore from the Dong Pao deposit, Vietnam, was investigated. The ore contained bastnaesite, (REE (rare earth element)) CO3F, as the valuable mineral and barite, quartz, and fluorite as gangue. To establish a mineral processing flowchart, selective comminution, size classification, and magnetic separation were tested. Bastnaesite shows brittle properties and selective comminution was applied to improve the purity of products. The crushed products were classified by decantation, and the overflow product showed high purity of bastnaesite indicating that bastnaesite becomes fines by crushing and that selective crushing can be used to concentrate the bastnaesite. Magnetic separation for the sink product was carried out and the mag-product showed high recovery rates of bastnaesite, indicating that the combination of size classification and magnetic separation is effective.

Aug 1, 2013

By Gennaro Delisle

"Les Services TMG (Niobec) currently treat a niobium ore in the Chicoutimi area of Quebec. The mineral pyrochlore is present in a carbonatite deposit which assays 5% to 7% apatite.The ore is ground to minus 65 mesh and deslimed at 10 micrometres. Part of the carbonates are floated with a fatty acid emulsion and rejected to the tailings as a first step to ensure the proper conditions for the flotation of the pyrochlore concentrate. The carbonate concentrate is 65% minus 44 micrometres and is composed of dolomite, calcite, 22% apatite and a minor amount of silicates.A laboratory investigation was undertaken to determine the feasibility of extracting apatite from the carbonate concentrate. This led to the development of an economic flowsheet to produce high-grade apatite concentrate. The apatite is depressed with phosphoric acid, and the pH is adjusted at 4.8-5.0 with sulphuric acid. An additional amount of fatty acid is added to permit efficient flotation of the carbonates. 1n a second stage, the silicates left behind with the apatite concentrate can be removed by depressing the apatite with AIC3 while floating the silicates with a secondary amine.The results of the laboratory tests indicate the possibility of producing an apatite concentrate assaying 38.3% P2O5 (83.7% BPL) with a recovery of 66.2%. Pilot-plant tests undertaken at the concentrator yielded a concentrate of 34% P205 and recovery of 76%."

Jan 1, 1981

By M. S. Fotheringham

Recognition of the Growing Importance of Iron and Steel Few Canadians have yet become aware that Canada's vast iron ore resources, the greater part of which is only now beginning to be developed, will inevitably have a profound effect on the entire Canadian economy, benefitting in some measure the lives of all Canadians. The great iron mining developments of Ontario, Newfoundland, Quebec, and Labrador are destined to make Canada one of the world's major producers and exporters of this material, on which our industrial civilization is?based. These developments will create new employment, new communities, new transportation facilities, and new investment opportunities. Iron ore is the foundation and the keystone of modern mechanized civilization. The most prosperous nations of the world are the highest per capita consumers of iron and steel, and in these countries the per capita consumption is increasing steadily despite the advent of light metals, plastics, and other competitive materials. Three-quarters of the human race have too little steel -and consequently too little mechanization -to provide for themselves the necessities and comforts of civilized living. Progressively they will demand, and acquire, the machines, the transportation and communication facilities now lacking, and they will win them by making greater use of the world's iron resources. It is the good fortune of this generation that Canada's 'iron age' is just getting well under way.

Jan 1, 1951

By Louis Frost

"A FIRE which forced the sealing -of the east side of Dominion No. 16 Colliery in the Town of New Waterford, Nova Scotia, occurred on October 6th, 1952 (Figure 1).So far as can be ascertained, the fire was first noticed in the roof of No. 7 East Lateral, after a brushing shot had been fired in the pavement. There appears to .be no doubt that this shot •blew out, igniting a small feeder in the roof.Regular air measurements and air samples, taken over a long period prior to the fire, indicated that the ventilation was adequate, for at no time had the percentage of CH4 in the general air current exceeded one per cent in this location. The last regular monthly samples and air measurements, taken at the end of September, showed the condition of the ventilation to be:Return at the Top of No. 8 East WallQuantity .... 27,700 cu. ft. per min.CH4 .......................... 0.32 per centC02 ................................ 0.10 per centHowever, in the week preceding the fire the mine examiner on four occasions had reported small feeders of gas at the face of the brushing in No. 7 East Lateral.Figure 2 is a diagram of the working place where the shots were fired. The face brushing had been shot down at 3 :45 p.m. and cleaned up. Two 'hurdle screens' had also been erected, one close to the face brushing and the other fifteen feet from the face."

Jan 1, 1953

By Z. B. Karshigina, Ye. G. Bochevskaya, E. A. Sargelova, Z. S. Abisheva

At the present time of depletion of reserves of high grade rare earth deposits, it has become necessary to involve low grade raw materials in the production. Among the rare-earth deposits in Kazakhstan, the most advanced one is Kundybai. The mineralogical composition of ore is represented by the minerals: a-quartz SiO2, kaolinite Al2(Si2O5)(OH)4, muscovite KAl2(AlSi3)O10(OH, F)2, albite Na(AlSi3O8), rutile TiO2, and hematite Fe2O3. It contains: 59.1–68.5% SiO2, 19.1–28.4% Al2O3, 7.2–10.3% Fe2O3, 0.51–0.84% TiO2, 0.10–2.32% CaO, 0.39–2.10% MgO, and some other elements. Rare earths are located in the clay part (kaolinite, goethite) in the ion-adsorbing form, and they are represented by the main ore mineral churchite - YPO4·2H2O. In the ore the amount of rare-earth elements (total REEs) varies from 210 to 600 ppm. Elements of the cerium group predominate (La, Nd, Ce, Sm, Pr) and the yttrium group is represented by Y, Gd and Dy. Extremely thin intergrowth and accumulation of REEs in clay minerals cause difficulties in their recovery using flotation and gravitation beneficiating methods. The purpose of this work is the development of an extraction method for the main mineral components of ore with transfer of the total REEs into the solution with high extractive efficiency. Results of the experimental work into high-temperature processing (hereinafter referred to as sulphatization) of ore by sulphuric acid with subsequent dual-mode water leaching of the sulphate product (sinter) are presented in this manuscript. The influence on the ore sulphatization process of some physical and chemical parameters: liquid-to-solid (L/S) ratio (0.36–0.86 cm3/g), temperature (100 – 500°?), concentration of sulphuric acid (3.0–18.62 mol/L) and duration (0.5–2.5 h) was studied. Optimal technological parameters of the process were determined to be: L/S ratio 0.36–0.46 cm3/g; temperature 500°?; concentration of H2SO4 9.0 mol/L; soaking time 1.5 h. Under these conditions it is possible to obtain extractions of ~ 85% REE, as well as 58% aluminium and 10% iron. XRD and IR-spectroscopy analyses were used to determine the material constitution of sulphated cakes obtained under optimal conditions. It was found that the primary minerals are quartz and muscovite; however different sodium aluminium silicates and albite minerals are present as well. In the future, it is proposed that the leach residue cakes are processed into precipitated silica (“white soot”).

Jan 1, 2016

By Laszlo Imreh, Pierre Trudel, André C. Tessier

"The Siscoe gold mine is ranked as the fourth largest mine in the history of the Val d' Or mining district with a total production of 27.4 tAufrom1929 to 1949. Most of the gold mineralization occurred in quartz veins, hosted in a small (.69 km2) intrusion of altered quartz gabbro known as the Siscoe stock. The southern contact of the Siscoe stock is crosscut by a major shear zone (the ""K"" zone) trending 295/80 NE and from which gold mineralization was also exploited within the limits of the stock. Field and petrographic observations of the Siscoe stock combined with chemical analyses of major, trace and rare earth elements of the stock and its volcanic host rocks (Dubuisson Formation) suggest that:The Siscoe stock comprises four alteration facies formed from a homogeneous precursor: 1) the actinolite - Mg-chlorite facies, characterized by low FeOt,Na2O andTiO2 , and highAlp3 and MgO; 2) the albite- Fe-chlorite facies, containing high concentrations of FeOt and Nap; 3) the Mg + Fe-chloritefacies, which is transitional between the actinolite- Mg-chlorite and albite- Fe-chloritefacies; 4) the carbonate-chlorite facies, which consists of rocks that were subjected to extreme hydrothermal alteration, is spatially associated with mineralized veins and part of the K-zone. The first three facies are depleted in SiO 2, CaO and Au, and enriched in MgO, relative to fresh rocks of the Siscoe stock and the equivalent rocks of the Dubuisson Formation.Hydrothermal fluids introduced mainly along the K-zone ""channelway"" induced three types of element remobilization, resulting in the various alteration facies: 1) redistribution of elements within the stock from one facies to another (e .g., FeOt, Nap, Ti02 migrated from the actinolite- Mg-chlorite facies to the albite- F e-chlorite and Mg + Fe-chlorite facies); 2) remobilization of elements from the intrusive rocks into veins (e.g ., SiO 2 and CaO ); 3) introduction of elements by hydrothermal fluids in rocks of the Siscoe stock (e .g., Al2O3, MgO, H2O, CO2 and FeOt).The Siscoe stock and the Dubuisson Formation form part of the same tholeiitic suite. Similarly, the Bourlamaque batholith and the Val d'Or Formation belong to a single calc-alkaline suite. In view of this relationship, dissimilarities between the petrochemistry of the Siscoe stock and the Bourlamaque batholith suggest that the two intrusions are not co-magmatic.Finally, gold may have been leached from rocks of the Siscoe stock and remobilized into the quartz-carbonate mineralized veins. In order to account for the total production at the Siscoe mine, approximately 1.2 km3 of the Siscoe stock is thought to have been partially leached of its gold."

Jan 1, 1990

By H. J. McQueen

Large-scale industrial production of pipe began with longitudinal hot pressure welding of wrought iron by passage of skelp (narrow strip with beveled edges) through a die or bell that curled it about a longitudinal axis until the edges were forced together. Such small to medium tubes could be reduced by rolling or drawing; with threaded connections, they were excellent for distribution of clean water and of illuminating gas for street, home and industrial lighting. Although steel lacks the fluxing slag for pressure welding it has hot strength similar to iron; hot-pressure bell welding was advantageously transferred to steel in long coiled strip with 50% higher cold strength. For pipe without weld-line defects, hot cupping followed by Pilger mill rolling produced tubing that revolutionized bicycle quality and high-pressure service for boilers and chemical processing. Mannesman hot rotary piercing produced long thick walled tube that permitted reduction or expansion by rolling to provide pipe sections up to 60 cm diameter and 12 m long. During 1910 - 1940, oil and gas pipeline technologies, notably welding evolved markedly as they proliferated in the United States, in response to far-flung petroleum fields, expanding industry consumption and the automobile revolution. In the Second World War combat pipelines were laid rapidly, such as: the Canol line through the Yukon to Alaska, and fuel supply lines across the channel and through liberated France. Perfection of welding techniques for both longitudinal and spiral weld large diameter pipe in combination with controlled-rolling of micro-alloyed steels made possible reliable Arctic pipelines. The development of pipe production and utilization in Canada is recounted. The fabrication techniques and metallurgical controls are explained.

Jan 1, 2005

By A. Brown

The swift decline of coal during the period of unprecedented expansion in the Canadian economy is a phenomenon deserving careful examination, because the underlying forces contributing to this decline may have broader implications in our national economy. At the present level of technology, coal is more difficult to process, transport and utilize than liquid and gaseous fuels. Fundamentally, it is a matter of limitation in technique. Because coal is a vast store-house of energy in Canada, the reduction of these limitations is in the long-term national interest.

Jan 1, 1967

By P. Groleau, O. Tavchandjian, D. Marcotte

In open pit mining, each small mining unit (SMU) is selected for mill processing based on an estimate of its true grade. The estimation is usually done using analyses of cuttings from blast holes within that SMU. One common estimator used for selection is the arithmetic average of within-SMU samples. This estimator is conditionally biased. The effect of a conditional bias is to overestimate the profit really recovered from the deposit. For this reason, a conditionally unbiased estimator is preferable. Increasing the number of samples generally improves the accuracy of the estimation (and diminishes the conditional bias, if present, of most estimators). However, there exists a practical limit where an additional sample does not improve the estimation sufficiently to cover the expense of making the analysis. This limit is specific to each deposit and depends on geostatistical parameters, economic factors, and mining parameters. This study examines how the number of samples affects the recovered reserves and the resulting profit. Also, the effects on optimal profit of varying the different factors are examined. Globally, the number of samples required increases with the selectivity of the operation. For a given ore deposit, the greater the number of SMUs selected for processing, the fewer samples are required and vice-versa.

Jan 1, 1998

By Xiong Tong, Jiushuai Deng, Yingbo Mao, Lingyun Huang

Ammonium carbamate has been used as a reagent for the leaching of copper from the copper oxide ore found in the Honghe state, Yunnan province, China. In order to find the optimal conditions for the leaching of copper from this copper oxide ore,the effects of several processing parameters, including the concentration, time, temperature, particle size and stirring intensity have been investigated. The results of these optimization experiments showed that the leaching rate of copper reached up to 72.76% under the following conditions: liquid-to-solid ratio of 10:1, ammonium carbamate concentration of 2.5mol/L, leaching temperature of 45 °C, stirring speed of 300rpm, a reaction time of 1.5 h and 85% by weight thereof passes through a sieve having 0.074 mm.

Jan 1, 2015

By C. H. Tiernon

"This paper was' prepared to emphasize the part that coal washing tables can play in the development of many of the reserves of coking coals in Western Canada_ It covers a brief history of the development of the coal washing table through the present third-generation unit, which suspends from overhead steel beams and is driven by a counter-rotating gear mechanism. The design and operation of this unique table are covered in detail.An analysis of actual operating data is included, with explicit statistical breakdowns of the table products. The data used were actually produced by operating coal companies, and also produced by the United States Bureau of Mines while gathering data for a research investigation. Table feed capacity is discussed, as well as performance criteria and the parameters of relative table performance. Several typical table flowsheets are described, emphasizing the specific reasons for their use. The paper covers the past and present value of the table to the United States coal industry, and makes mention of the newest addition to the family of suspended, multiple-deck, counter-rotating, gear-driven, coal washing tables, the CONCENCO ""88"" Deister table."

Jan 1, 1973