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By K. A. Natarajan, S. C. Riemer, I. Iwasaki

The relative significance of corrosive and erosive wear in magnetic taconite grinding is examined. The influence of different types of aeration (nitrogen, air, and oxygen) on ball wear was established for mild steel and high carbon low alloy steel balls. Ball wear data from dry and wet grinding tests are compared with those obtained in the presence of an organic solvent that does not promote electrochemical corrosion. Marked ball grinding tests and electrochemical measurements involving ball material and magnetite electrodes indicate that contribution from oxygen toward wear (corrosive wear) is relatively small, and abrasive wear appears to be significant. Rheological properties of the slurry appear to have an important bearing on the abrasive wear of grinding balls.

Jan 1, 1985

By Dr. G. R. Hoey

"Abrasive wear and corrosive wear of carbon-steel grinding balls occurred simultaneously during the wet-grinding of hematite iron ore, and Ni-Cu sulphide ore, in laboratory ball mills. Two corrosion control methods, the use of corrosion inhibitors and pH control, were investigated and found to be effective means of reducing or preventing corrosive wear. Up to 50 % reduction of total ball wear resulted from the use of these methods.Corrosive wear is caused principally by the reaction of oxygen in air with the carbon-steel grinding balls, probably by the following reaction: 2Fe + O2 + 2H20 - 2Fe2 + 40H-.IntroductionA survey of corrosion problems in Canadian sulphide ore mines was completed and the findings were published in 197l(l). The corrosion survey was used to develop the present research program with the objective to find more economical and effective ways and means to reduce the corrosion that occurs in the mining and metallurgical industry. The purpose of this presentation is to review the projects being done by staff members of the Corrosion Section, Extraction Metallurgy Division, on corrosive wear and its control in wet-grind ball mills.Both abrasion and corrosion contribute to metal consumption during wet grinding of ores. The total wear of grinding media in this study is assumed to be equal to the sum of corrosive wear and abrasive wear. A great deal of research and development has been reported in the literature on ways to improve the abrasion resistance of grinding media but only a small number of studies has been reported on the corrosion resistance of conventional grinding media."

Jan 1, 1974

By Freeman C, Dingley W

Addition of sodium nitrite-borax, sodium hydroxide, sodIUm carbonate, lime, or sodium silicate reduced wear of forged steel balls and cast iron slugs in wet grinding a complex zinc-lead-copper sulphide ore in laboratory ball mills. Maximum wear reductions were 27 per cent (forged steel balls) and 33 per cent (cast iron slugs) with sodium hydroxide and nitrite-borax additives respectively.Potential measurements of balls and slugs during grinding, and analysis of the data in terms of corrosion theory demonstrated that corrosive wear had been reduced or prevented by these additives. Actual per cent wear reductions were not equated to the rate of corrosive wear because of the undefined interdependence between abrasion and corrosion in wear processes. The investigation verifies that in laboratory ball mills corrosion is significant in the wear of grinding media and wear can be reduced by corrosion inhibition and pH adjustment.

Jan 1, 1978

By Shane Andrews, Gustavo Vasquez, S. K. Varma

"The effect of solutionizing time on the corrosive wear behavior of 2014 aluminum alloy has been studied using the impact and continuous mode of scratching techniques. The transient currents (TC) evolved during the scratching of the alloy shows a linear dependence between the TC and the solutionizing time. Higher TC values at longer solutionizing time may be associated with the changes in the concentration of quenched-in vacancies, grain sizes and dislocations generated during scratching. These factors can either create (a) anodic sites or (b) pitting corrosion resulting in the generation of transient currents. The results have been compared with the similar study carried out for 6061 aluminum alloys. This 6061 aluminum alloy shows similar behavior but the rate of TC generation per unit solutionizing time is much lower than 2014 aluminum alloy. The morphological changes in the impact scratches and the TEM investigation in the scratch have been presented in this paper.IntroductionThe technique of studying corrosive wear of composites of 6061 aluminum in the monolithic and reinforced forms has been reported in the literature [1]. Two modes of scratching, consisting of impact and continuous, in a corrosive environment indicate that the composites, containing 0.10 and 0.20 volume fractions of alumina particles (VFAP), have higher corrosive wear rates than the monolith. A graph between the transient current (TC) generated during the impact scratching as a function of solutionizing time at 540°C indicates linear relationship between them. A similar slopes for the composites were observed and the TC values were less for the composite containing lesser VFAP."

Jan 1, 1998

By Bryan de Barros Soares

O aço carbono é um material amplamente empregado na indústria petrolífera devido sua elevada resistência mecânica e baixo custo. Entretanto, este material não possui boa resistência à corrosão. Neste contexto a predição da taxa de corrosão é de extrema importância para estimar a durabilidade desses materiais. Atualmente isto é feito com base em dados de ensaios de perda de massa em um único tempo de imersão, estimando-se a taxa de corrosão. Contudo, para converter os dados de perda de massa em taxas de corrosão é imprescindível que os ensaios sejam conduzidos em diferentes tempos de imersão e que haja linearidade entre perda de massa e tempo. Neste trabalho a corrosão do aço carbono em meios saturados com CO2 foi investigada através de ensaios de perda de massa em três tempos de imersão diferentes, com o objetivo de avaliar essa linearidade. Dos quatro meios corrosivos estudados, um não apresentou linearidade entre PM e tempo de imersão, sendo portanto incorreto extrapolar os dados para taxa de corrosão. Os resultados comprovaram que a extrapolação de dados de PM para taxas de corrosão não pode ser aplicada sem uma prévia verificação da linearidade entre perda de massa e tempo de imersão.

Aug 16, 2017

By Lucas Coelho da Silva

Este trabalho tem a pretensão de problematizar a influência da corrosão, sobretudo nos trocadores de calor, e trazer a importância de um estudo prévio detalhado, ressaltando como o desempenho deste equipamento está relacionado ao material utilizado e como esse estudo pode nos abster de grandes dispêndios. Através de ensaios eletroquímicos vamos estudar o comportamento do aço Super Duplex UNS S32750 em diferentes meios corrosivos, com o intuito de avaliar se o nível de corrosão do material é adequado para as condições severas de operação impostas a um permutador de calor.

Aug 16, 2017

By José Helio Sobrinho

O aço inoxidável austenítico alto nitrogênio ISO 5832-9 tem sido promissor na manufatura de próteses ortopédicas com resistência mecânica e de corrosão superiores a do aço tradicional ASTM F-138. Pesquisas recentes têm mostrado que esta liga apresenta resultados peculiares, tais como alta resistência mecânica, resistência à corrosão e presença de partículas de segunda fase (Fase Z) na matriz. Entretanto, não se sabe como se dá a correlação mecânica-microestrutural e de taxa de corrosão em regiões de processabilidade industrial desta liga na conformação a quente de peças. No presente trabalho, ensaios sob torção a quente isotérmico contínuo e interrompidos foram realizados após tratamento térmico de solubilização a 1.200oC, por 300 s com intervalos de temperatura variando entre 1.000°C e 1.200oC com taxa de deformação variando entre 0,05 e 5 s-1, para investigar a trabalhabilidade e a taxa de corrosão sob tensão desta liga com aplicação da técnica de espectroscopia de impedância eletroquímica e caracterização microestrutural, conduzida por microscopia óptica e varredura. Os resultados mostram que a tensão de escoamento é sensível aos parâmetros de deformação. O pico de tensão diminui com o aumento da temperatura e redução da taxa de deformação com alta taxa de recuperação dinâmica com grãos alongados, gerando regiões de acúmulo de tensão. Essas regiões de instabilidade plástica apresentam grau de corrosão superior em relação às amostras como-recebidas. As regiões de alta temperatura e baixa taxa de deformação apresentam boa trabalhabilidade com microestrutura final refinada com grãos recristalizados dinamicamente.

Aug 8, 2018

By Raphael França Assumpção

O aço inoxidável duplex (AID) vem sendo considerado uma excelente alternativa para aplicações que requerem alta resistência à corrosão e alta resistência mecânica. Portanto, a microestrutura e as propriedades dos aços dúplex permanecem como temas de grande interesse. Para este proposito, estudou-se o efeito da laminação a morno em um aço inoxidável duplex. O foco deste trabalho foi o AID 2205 que é um dos tipos mais comuns de AID. O objetivo deste estudo é avaliar o comportamento eletroquímico do AID 2205 laminado a morno no ambiente de íons de cloretos utilizando medidas de polarização potenciodinâmica. O aço inoxidável dúplex foi laminado a morno à 600°C para 60 e 80% de redução na espessura e submetido a testes eletroquímicos. As amostras apresentaram uma excelente resistência à corrosão em solução de NaCl 3,5%. Apesar da existência de certa similaridade entre os valores de potencial de circuito aberto e potenciais de pites obtidos para todas as amostras, o número de pites observado foi maior na amostra CF, seguida pelas amostras com 60 e 80% de redução.

Oct 30, 2017

By Jorgen Elbrond, Noel Billette

"La connaissance du niveau de variation de I' alimentation d' une usine minéralurgique est essentielle pour estimer le taux de récupération dans un concentrateur. De plus, il est important de connaître la période moyen ne de correlation afin d’améliorer la qualité des contrôles et de l' au tornatisation.Le modèle proposé permet de prédire ces paramètres à partir du minerai en place et des activités d'exploitation dans une opération à ciel ouvert. II est basé sur la combinaison des variogrammes directionnels dans diverses zones d'un gisement, ce qui permet de définir la correlation à la sortie de chaquc zone en fonction des decisions opérationnelles, puis sur une loi binômiale modifiée, afin de séparer minerai et stériles dans Ie but de décrire variance et corrélation dans Ie minerai même, Les statistiques classiques sont alors utilisées pour décrire la combinaison de plusieurs zones et obtenir la variance et la correlation au concentrateur.IntroductionUn concentrateur est habituellement rodé de facon à recevoir une alimentation à teneur fixe en métal ; Ie minerai qui s'y presente a, par contre, tendance à osciller auteur de cette valeur cible, tantôt plus riche , tantôt plus pauvre . Ces variations entraînent des pertes de deux types: tout d'abord, la teneur du concentré oscille de facon similaire à celle de l' alimentation , ce qui peut même impliquer des pénalties a I'usine de smeltage lorsqu'elle est trop riche ou trop pauvre; la récupération peut pour sa part être diminuée de plusieurs points par un engorgement du circuit lorsque la teneur est trop forte."

Jan 1, 1984

By Benjamin A. Allou

La seule production de columbo-tantalite réalisée en Côte d?Ivoire est effectuée dans les éluvions et alluvions du gisement d?Issia, localisé au Centre- Ouest de la Côte d?Ivoire. Même si un lien direct avec les roches granitiques est suspecté, aucune attention particulière n?a été accordée à l?étude de la minéralisation primaire en relation avec l?évolution des granites et des pegmatites associées. Ces granites, qui sont en intrusion dans les roches sédimentaires du Protérozoïque inférieur, comprennent : le granite orienté à deux micas (Lobo), le granite orienté à muscovite dominante (Bitapia) et le granite porphyroïde non orienté à muscovite dominante (Issia). Les résultats de cette étude indiquent que les pegmatites à Nb-Ta-Be-Li sont liées au granite de type Issia. Les observations de terrain et les analyses sur roche totale des granites montrent que: (1) les trois principaux granites de la région sont de type- S et peralumineux dans leur composition, (2) ils ont été formés pendant la période tardi- à post-Éburnéenne, (3) le granite d?Issia fut le dernier à se mettre en place. Les pegmatites liées au granite d?Issia ont été classées en quatre types : Apegmatites stériles; B- pegmatites à Be; C- pegmatites zonées à Nb-Ta-Be; et Dpegmatites zonées à Be-Nb-Ta-Li. Les pegmatites zonées comprennent les zones suivantes: I- zone à aplite; II- zone graphique; III- zone à albite, microcline, béryl et columbo-tantalite; IV - zone à microcline massive; V- zone à quartz. Ces pegmatites présentent une zone d?altération métasomatique externe. La minéralisation de Ta, Nb et Be est liées à la zone III des pegmatites de types C et D, et celle de Li est associée aux greisens qui peuvent être observés n?importe où dans les pegmatites de type D. Les données de terrain et de laboratoire indiquent que le granite d?Issia est la roche parentale des pegmatites à éléments rares de la région. Les pegmatites minéralisées sont distribuées seulement autour du granite d?Issia et les patrons des terres rares des granites et ceux des pegmatites à éléments rares sont très similaires. Les analyses de la composition totale montrent un lien génétique entre le granite d?Issia et les pegmatites à éléments rares. Il est suggéré que les pegmatites ont été formées durant le transport et la cristallisation fractionnée du magma.

May 1, 2003

By Ángel Cabello Victoria

El presente trabajo es un estudio técnico-económico del yacimiento minero Caridad, perteneciente a la compañía del mismo nombre en Lima, cuyas características permiten aplicar el método de corte y relleno en la minería en vetas de plata. Sin embargo, las bajas cotizaciones en el mercado mundial de los metales, minimizaron los costos de los mismos y aumentaron la productividad para mantener la mina en operación. Por tal motivo, se busca utilizar este método en pequeñas minas de plata que tienen características similares y asi recuperar el minado completo de los valores en plata, la eficiencia en la mecanización de los equipos de acarreo y volteo y reducir los accidentes por caídas de rocas, como causa principal en la minería subterránea.

Nov 8, 1982

Cortez Gold Mines operated a conventional 2,100 mtpd (2, 300 stpd) cyanidation plant until the 5 million ton ore body was worked out in 1973. (See Gold and Silver Cyanidation Plant Practice by F. W. McQuiston, Jr. and R. S. Shoemaker, Society of Mining Engineers, AIME 1975.) Sub-grade material was dump leached at the mine -mill location in 1971, and the resulting pregnant solutions were added to the feed in the plant's Merrill-Crowe precipitation unit for gold recovery. In early 1973, however, Cortez put into operation their Gold Acres mine which was located about 13 krn (8 miles) to the west of the 'Cortez mine. Economics at that time dictated the heap leaching of the lower grade portion of the ore body with the higher grade being trucked to the Cortez plant for milling. Leach ore was moved directly from the open pits to prepared leach pads located on a gently sloping terrain of 570 grade. Preliminary pad preparation at the leach site included removal of vegetation which was composed of sagebrush and grading of the base. Pads were comprised of mostly minus 74 micron (200 mesh) materials and were made of clay-silt or slime tailings spread on the pad area in thin 50 to 75 mm (2 to 3 in. ) layers, compacted with a vibrating roller compactor to a depth of about 380 mm (15 in.). This was followed with a 100 mrn (4 in.) layer of coarse rock to prevent erosion on the pad and to allow solutions to move laterally under the heaps. Leach solutions normally traveled the length of the heaps and were collected in plastic-lined ditches from which they flowed by gravity to the pregnant solution storage pond. Both pregnant and barren ponds were constructed in the same manner as the leach pads - being lined with compacted tailings or clay silts. The Gold Acres facility required pregnant solution storage of 6 million liters (1.6 million gal) and barren storage of 3.8 million liters (1.0 million gal) designed to handle two to three days of heap drainage or to retain run-off from a major rainfall. Various heap heights were tried including 3, 6, and 9 meters (10, 20, and 30 ft), with a 6 m (20 ft) height selected. Ore was dumped by trucks in a single 6 m (20 ft) lift using a D8 Caterpillar dozer for

Jan 1, 1981

By Ralph L. Erickson

The discovery of a Carlin-type gold deposit at Cortez, Nevada, in 1966 can be attributed directly to the use of geochemical exploration techniques. Most mineral deposits owe their discovery to geologic concepts, geologic analysis, and luck, but at Cortez, geochemistry as an exploration tool played the clearly dominant role in discovery. Of course, the economic significance of the discovery had to be determined by exploration and development drilling. The story of the discovery began in 1959 when field work was initiated on a new project, "Geochemical Halos Utah and Nevada," by R.L. Erickson and A. P. Marranzino for the US Geological Survey. The Cortez district was selected for geochemical work because it was an area with good geologic control where we could address the problem of how to prospect in barren outcrops for concealed ore deposits in potentially favorable structures (buried thrust zones) or favorable host rocks in the subsurface. Geologic mapping of the Cortez 15-min quadrangle, just being completed by Gilluly and Masursky (1965), showed that the quadrangle contained excellent exposures of both the upper and lower plates of the Roberts Mountains thrust fault, a major structural feature of north-central Nevada. Roberts (1960) had noted that a number of mining districts were associated with windows in the thrust. In 1959, Erickson and Marranzino did some reconnaissance rock sampling and spring-water sampling in the siliceous clastic rocks of the upper plate of the thrust. Results of this reconnaissance prompted a full-scale sampling program in 1960 in the upper plate rocks on the west flank of the Cortez window. Results of the investigation showed that anomalously high concentrations of metals occur in the upper plate rocks, and further, that the distribution of metals is fault controlled and shows a pronounced zoning pattern (central copper zone; intermediate zinc, copper, and lead zone; and outer arsenic zone). The anomalies were interpreted as primary leakage halos that originated from metal occurrences in the thrust zone or in carbonate rocks below the thrust and moved upward along normal faults that cut both upper and lower plate rocks. Erickson gave a talk about these anomalies in the summer of 1961 to the local AIME Section in Reno, Nevada; two short reports were published that year-" Geochemical Anomalies in the Upper Plate of the Roberts Thrust Near Cortez, Nevada" (Erickson et al., 1961) and "Hydrogeochemical Anomalies in Four Mile Canyon Near Cortez, Nevada" (Erickson and Marranzino, 1961). These releases prompted blanket staking in the area by several small companies. In 1963, geologic and geochemical mapping were started by the USGS in the lower plate carbonate rocks of the Cortez window west of the quartz monzonite stock at Mount Tenabo and north of the old townsite of Cortez. The results of the work showed anomalously high concentrations of arsenic, antimony, and tungsten in jasperoid, fracture filling, and shear zones in Silurian and Devonian carbonate rocks. The anomalous area was about 1.6 km (I mile) long and 300 m (1000 ft) wide. A brief report, "Geochemical Anomalies in the Lower Plate of the Roberts Thrust Near Cortez, Nevada" (Erickson et al., 1964a), was published in 1964. During this same time period, 1959-1964, several exploration or mining companies were active in the general area (chiefly mapping geology and acquiring property). In 1964, American Exploration and Mining Company (Amex) concluded that the entire Cortez district was worthy of an extensive exploration effort involving drilling as well as geologic, geophysical, and geochemical studies. To carry out the program, Amex formed a joint venture group with the Bunker Hill Company, Vernon Taylor, Jr., and Webb Resources. Their early efforts were directed to the upper plate rocks and to the lower levels of the old Cortez silver mine. The group also drilled some shallow rotary assessment holes adjacent to the area of the arsenic, antimony, tungsten anomaly in lower plate carbonate rocks described in Erickson et al. (1964a). Assay results from these holes offered little or no encouragement to the joint venture group. Splits of these drill samples were made available to the USGS. In order to enhance any metal content present in these rocks and to determine the mineral residence of any metals detected, heavy-mineral concentrates of each 3-m (10-ft) sam-

Jan 1, 1985

By Roland D. Parks

CORUNDUM, little publicized as an industrial abrasive, has, in its small way, contributed greatly to the production of many specialized items vital to our war program and to our allies. Optical elements of the highest quality for range finders, bombsights, and scientific instruments; precision metal parts for torpedoes and airplane engines; quartz crystal plates for military radios; armorplate and malleable castings for tanks and guns; and eyeglasses for everyone; these are some of the products that corundum has helped to produce in the quantities needed and on time. Unlike metals and many other raw materials, corundum is not incorporated into any of these finished products. It is simply a grinding medium used to produce the desired finish or precision; an operating supply or tool, so to speak. With a Mohs' scale index of o, corundum ranks next to the diamond in hardness among the natural minerals and is superior to emery and garnet. The gem varieties of corundum, including the Oriental ruby and sapphire, are frequently more highly prized as jewels than the diamond. It is the intent of this paper to deal only with a description of the corundum industry, the administration of wartime control, and certain economic aspects as seen by the author. Several references are listed to assist anyone who wishes further information on the geological occurrence of the mineral. ORE PRODUCTION AND CONSUMPTION For the past two decades, South Africa has been the world's sole producer of corundum ore. A possible exception is Russia, where, it is understood, there was considerable production during the thirties for domestic consumption but for which statistics are lacking. The United States is the world's principal consumer of corundum ore; imports for the period 1934 through 1940 averaging 3000 short tons per year. The years 1935 and 1936 were close to the 5000-ton mark, and imports during 1941, the last prewar year for which statistics have been released, were approximately 6000 short tons. Again lacking statistics on Russia, the United Kingdom ranks second, but far below the United States in consumption of ore. Historically, corundum has been found in some 35 countries throughout the world, but the principal deposits are in South Africa, Canada, Madagascar, Russia and the United States. Deposits are generally small and subject to rapid exhaustion. Thus, the United States was the principal world producer for the period 1870 to 1900, when operations ceased except for two years during World War I. India was a producer of ore from 1898 through 1921, with peak output in 1916 through 1918. Canada came into production in 1901 with substantial output of ore and finished grain until 1914; the production thereafter was smaller until 1921. Madagascar has produced ore since 1910 but has had important output in only a few scattered years. South African production started in 1912,

Jan 1, 1945

By Lee W. Saperstien

Section 709 of Public Law 95-87, "Surface Mining Control and Reclamation Act of 1977," requests the National Academy of Sciences to determine if the standards of the act are applicable to minerals other than coal. The Academy has established the Committee on Surface Mining and Reclamation to respond to this charge. The committee is, itself, organized to be responsive to the varieties of minerals, environments, mining systems, and locations that are representative of U.S. mining systems. It is not the charge of the committee to write trial legislation, but to indicate whether or not technology, extant or proposed, is available to meet the standards of the law, and at what cost. It is within this set of conditions that the committee will examine blasting.

Jan 1, 1979

By Bill Birch, Toby White, Ian Brown

costs/benefits of electronic detonators and measure their effects on primary crusher productivity. 9 blasts (3 shock tube blasts, 6 electronic blasts). Measured electricity consumption & primary crusher throughput. Change to Electronic Detonators resulted in a 7% reduction in primary electricity costs and a 15% increase in primary crusher productivity.

Feb 1, 2020

By J. A. Bullington

Mr. Chairman and Gentlemen: Some of you men may know who are familiar with what we have been doing in the C. F. & I. the last three years, that we have revamped our entire method of cost accounting from the pit bosses' report through to the final report of the president. The basic ideas involved in our cost system are not ours. They were given us by one of the best management and industrial engineering concerns in the country-at least they have that reputation. All I can do now is to try to pass on to you some of the ideas we have from various sources and the methods we have used in teaching those ideas to our coal men on cost accounting. This will not be a technical paper. I tried to put it in language we could all understand, and I hope I will be talking the same language that you gentlemen talk when you think about the cost of your coal in your own mines. Accounting of all kinds is classed as overhead expense, and as overhead expense we must justify its cost by the service it gives the rest of the organization. That brings us up to the problem of making the cost department pay its own way, just the same as the power plant has to pay its own way, and we have gotten away from the old idea of cost accounting in that it is sufficient within itself. The cost sheets are only so good as they enable the operating man to reduce his costs. The cost sheets are only just so much work for the cost department, and if they do not help the operating man to control his costs, we figure that is so much work wasted. The cost department works for the operating department.

Jan 1, 1931

By R. V. Ramani, V. T. Burgos, J. A. McClay

Cost Systems Cost systems are organized methods of collecting, allocating, and accumulating resource utility expressed in terms of money. There are two major spheres of cost accumulation: financial accounting and cost accounting. Financial accounting deals primarily with historical costs and provides a means of measuring and recording cost events which have al¬ready taken place. While there are no legal requirements to control the methods of recording and reporting cost data in the United States, the procedures in use are guided by professional organizations such as the American Institute of Certified Public Accountants. The final pro¬ducts of financial accounting practices are the income statement and balance sheet which describe the financial status of the organization under study. Cost or managerial accounting is an expansion of financial ac¬counting procedures, providing more detailed cost breakdowns on present operations with one objective being the projection of present costs into the future. The projection process tends to limit the accuracy of the information; however, to management and project justification per¬sonnel, data on future operations tends to be of greater value. The basic principle behind cost accounting is the cost cycle. As products are developed from raw materials, the value of the work-in¬process increases due to the cost input of the various fabricating ele¬ments. Thus, from the basic input elements of facilities, labor, and raw materials, costs are added to each unit of production as a function of the work performed on that unit.

Jan 1, 1975

Estimate costs for projected uranium in-situ mining operations. Approach Develop a computer model and an associated data base which will allow users to supply data applicable to a specific mining site in order to estimate total capital and operating costs for a potential in-situ mining operation at the site. How the Model Works The model requires a minimal amount of input from the user. The data input must be known or estimated information about a potential in-situ mining operation. The user can also supply any additional project specifications. The computer model uses a process-engineering approach and determines through a discounted cash flow analysis the total capital and operating costs for the life of the project. This time-span measures from the start of the pilot-scale operation through to the site's restoration and reclamation. The model will determine the production cost per pound of material mined subject to the rate of return identified by the user. Conversely, it will also solve for the rate of return realized for the specific sales price per pound. [ ] Currently the model's data base can tai ns costs, rates, and specifications for Texas and Wyoming, the only states where commercial uranium in-situ mining is being conducted. However, this model can be used by anyone who is conducting in-situ leaching or who plans to leach uranium in-situ. At least part of any uranium deposit has a potential for in-situ mining.

Jan 1, 1982

By P. K. Chatterjee, G. D. Just

Sublevel open stoping is a low-cost method that has been successfully employed in many large underground mining operations. Where ore body characteristics are suitable, extensive mechanization and the use of large-scale stoping techniques can considerably reduce operating costs. However, careful long-term planning of mine layouts and large capital commitments in development are required prior to production. Implementing precise mine design procedures and carefully controlling operations can result in considerable benefits. This article describes methods to achieve these objectives based largely on mining operations at Mount Isa, where sublevel open stoping has been used since 1932. Ore won by this method accounted for a very large percentage of the total tonnage produced at Mount Isa. Major costs associated with sublevel open stoping can be classified as drilling, explosives and charging, and LHD costs. In this article, analyses of these costs are made with particular reference to stope design. Parameters such as burden, drill hole diameter, explosive density, specific charge, etc., are considered in establishing the interrelationship of unit operating costs, as well as total costs of sublevel open stoping.

Jan 10, 1981