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By S. L. Zekovic

This paper analysis the medium and long-term perspectives, framework and considered possibilities of sustainable development of RTB "Bor" (Copper mines in East Serbia) after consolidation in the period of transition. The copper mine was opened in 1903. and today is the best quality copper producer on Balcan. This paper are elaborates the problems of privatization, debt, investment, growth of copper production from own mines (and imported raw), opening of new mines, economical efficiency of production, markets, environmental problems and impacts of the recent industry consolidation. The RTB "Bor" is a serious hot spot in Serbia. Unsustainable trends and processes are identified, as follows: open-pit waste dumps, flotation tailings, mining and processing waste waters, air pollution; no efficiency (excessive) using nonrenewal resource in the copper production; inefficiency in the use of energy, water and other inputs in copper complex; transboundary character of emissions of dust; environmental degradation and quality of wide area and ecologically highly risk, etc. Analysing some trends and planning-developmental perspectives and development strategies of company, it might be assumed that in the forth coming period, in parts of the Serbia, the borders areas of Bulgaria and Romania, there is an anticipated increase of ecological risk.

Jan 1, 2007

By Kiyotaka Ohno, Nobushige Yasuoka, Yosuke Hioki

"The diameter of improved columns adopted by the original DJM Method had been 1000 mm, however, in order to comply with the social need for construction cost reduction, the Expanded Dry Jet Mixing (EX-DJM) Method with maximum column diameter expanded to 1300 mm was developed between 1998 and 2001 and has been widely applied since then. From the first application of EX-DJM in January 2002 for a first construction project, the total volume of improved soil has reached 325,000 m3 in 17 projects up to September 2014. Because of the advantages of the EX-DJM such as reduction of construction costs and periods leading to reduction in the number of improved columns, adoption of this method is expected to increase in the future. This paper describes the advantages of the EX-DJM, its construction results and case examples including those applied to restoration projects after the Great East Japan Earthquake, 2011.1. BACKGROUND OF DEVELOPMENTThe Dry Jet Mixing (DJM) Method is a soil stabilization method in which a powdery or granular binder is pneumatically fed into and mixed with soft soil to induce chemical reactions that stabilize and strengthen the soil. It was developed by government - private collaboration in Japan between 1977 and 1979. Up to March 2014, the total volume of soil improved by DJM method reached 33,500,000 m3. The initial diameter of improved columns of the original DJM Method was 1000 mm. In order to comply with the social need for construction cost reduction, the Expanded Dry Jet Mixing (EX-DJM) Method with maximum column diameter 1300 mm was developed between 1998 and 2001.2. ADVANTAGES OF EX-DJMThe construction equipment for the EX-DJM consists of two major parts, which are DJM machine and binder plant are shown in Fig. 1.The construction machine is of double mixing-shaft type with its column diameter expanded to 1200mm or 1300mm. In association with the increase in the column diameter, the binder feeder has also increased its discharge rate by approximately 1.69 times. Same as the increase rate of the area of original diameter 1000mm to diameter 1300mm are shown in Fig. 4."

Jan 1, 2015

By Mary Herrera Maldonado

El presente trabajo señala el uso de microorganismos en el proceso de lixiviación de los minerales a través del aislamiento, catalogación e identificación de esta bacterias oxidantes de azufre, a fin de utilizarlas en reacciones energéticas junto con el sustrato mineral para así comprobar la lixiviabilidad bacteriana por medio de una adecuada extracción de cobre. Para ello, se utilizó material procedente de Cerro Verde, donde se buscó lograr una lixiviación ácida por medio del ácido sulfúrico producido por las bacterias Thiobacillus, obteniendo satisfactoriamente minerales de tipo chalcopirita y calcosita iones solubles, entre otros importantes minerales.

Nov 20, 1978

By Antonio Augusto Gorni, Kenji Camey, José Herbert Dolabela da Silveira

Recently several studies have been developed on the use of microalloyed steels with low Mn content (below 1%) in the controlled rolling of heavy plates for the manufacture of pipes. However, this novel concept of alloy has peculiarities in its thermomechanical processing. Lower Mn contents should lead to the acceleration of NbCN precipitation kinetics during rolling, leading to a reduction in the soluble Nb content in austenite that delays its recrystallization by drag effect. This fact, plus the heavy and fast passes applied under virtually isothermal conditions in a heavy plate rolling mill with high power, increases the risk of partial recrystallization during the finishing stage of the controlled rolling, since strain hardening of austenite becomes significant and the interaction between precipitation and recrystallization is increasingly delayed. The objective of this study was to analyze the evolution of mean flow stress during the finishing stage of controlled rolling in these low Mn, high Nb microalloyed steels, in order to better understand the metallurgical mechanisms acting during this process and identify conditions that allow full compliance with the requirements of this product class.

Oct 1, 2019

By J. W. Town

The Bureau of Mines made continuous-circuit beneficiation studies to determine the optimum conditions for concentrating phosphate minerals from the intermediate-and marginal-grade ores of the Phosphoria Formation in southeast Idaho. Intermediate-grade ore was represented by a sample from Georgetown Canyon and marginal-grade ore from the Gay mine near Fort Hall. Two flow-sheets were developed: The first involved roasting, attrition scrubbing, sizing to remove a concentrate, grinding of the oversize, des liming, and flotation; in the other flowsheet roasting was eliminated. Controlled attrition scrubbing was used to remove clay and silt-size quartz particles imbedded in the phosphate pellets without breaking the pellets. The minus 35-plus 200-mesh fraction was removed by sizing as a finished acid-grade concentrate. The plus 35-mesh material was ground in a rodmill to minus 35 mesh and recycled to the attrition scrubber. The minus 200-mesh fraction was des limed at about 800 mesh to remove clay slimes and floated with 3 to 4 pounds of emulsion per ton of feed. The aqueous fatty-acid oil emulsion consisted by weight of 3 parts No.2 diesel oil, 3 parts crude tall oil, and 0.5 part water-soluble petroleum sulfonate.

Jan 1, 1967

By W. A. Wilkinson

Mine planners are under pressure to evaluate the impact of changing economic times and newly acquired data on their mine plans. Incorporating changes such as commodity prices, customer sales, fluctuating cost assumptions and newly acquired geologic data requires quick turnaround for model building and planning to keep mine plans on pace with changes as they occur. Because of the length of time required to perform some of the geologic modeling and mine planning tasks, planning frequency may not be keeping pace with the frequency of change. To meet these challenges, one leading North American mining company successfully increased the frequency rate and accuracy of its mine plans to stay current with incoming data, ensuring its mine plans reflect the latest information, thereby minimizing or eliminating production cost variance.

Jan 1, 2010

By Scott Dodds

"The Oxford Hydroelectric Station was a unique project that incorporated a variety of dam strengthening methods to stabilize the facility in order to meet the standards required by Federal Energy Regulatory Commission (FERC). The dam stability and Probable Maximum Flood (PMF) remediation work consisted of (1) construction of a new emergency spillway; (2) installation of 75 high capacity rock anchors; (3) construction of an anchored concrete powerhouse buttress; (4) construction of cast-in-place and sheetpile flood walls; and (5) design and construction of a permanent soil nail wall. INTRODUCTIONThe Oxford Hydroelectric Station is one of 11 hydroelectric facilities owned and operated by Duke Power along the Catawba/Wateree River. The Catawba River originates in the foothills of the Appalachian Mountains just west of Morganton, North Carolina. The river flows east out of the mountains and, at a point just below the Oxford Dam, the Catawba River turns and heads southeast. The Catawba River continues to flow southeast past Charlotte and into South Carolina where it eventually becomes the Wateree River. The Wateree River eventually flows in to the Atlantic Ocean.Located a few miles east of Hickory, North Carolina, the Oxford Dam and Hydroelectric facility is in the upper reach of the Catawba River. Oxford Dam creates the third impoundment along the river known as Lake Hickory. Lake Hickory is well known locally for providing many outdoor activities such as boating, jet skiing, canoeing and fishing. The dam and powerhouse were put into operation in the spring of 1928.Key features of the dam include a short embankment section on the south end of the structure, a 391-foot (119m) long south bulkhead and powerhouse, 540-foot (165m) long gated spillway section and a 235-foot (71.6m) long north bulkhead. The maximum height of the dam is approximately 100-feet (30m) from the crest to the dam/rock interface. (See Figure 1).The work associated with this project is the result of licensing requirements of the Federal Energy Regulatory Commission (FERC) which mandates that all hydroelectric facilities have the capacity to safely discharge runoff created by a critical rainfall event defined as the probable maximum flood (PMF). Duke Power, a division of Duke Energy (DUKE) submitted an initial PMF report in 1992 which indicated that at the Oxford Dam would be overtopped by approximately 10-feet of water during the modeled PMF event. Given the duration and depth of the overtopping, significant damage to the facility and a possible breach could result. Therefore, modifications to the existing facility were necessary to satisfy the report of the PMF model."

Jan 1, 2005

By R Rimmelin, C Vergara

Heap leach pads are composed of mined ore, usually crushed, disposed on liners to be processed with leach solutions, and the tail of the process is called “spent ore” which are then transported by conveyor belts to be disposed into dumps. It is often to observe stability problems in these dumps, that could affect the equipment working on it and the continuity of the whole mine process. These problems are related to an excess of water content at the spent ore, therefore the operational efforts are focused onto control this geotechnical parameter.This work presents the results of different geotechnical laboratory testing, using samples of spent ore of a mining operation in the north of Chile. In the last 10 years, 3 campaigns have been made to get samples. Valuable information was obtained to identify how specific operational/metallurgical factors could affect the geotechnical behaviour of the spent ore. Special attention is given to the decision to change the metallurgical process adding salt to the heap leach process and its impact to its hydraulic conductivity.Historically, the process has been based on the leaching of oxides and sulphides materials, in separate campaigns, in which it is possible to observe different geotechnical response in the spent ore generated. Recently, it was implemented a new process in which the materials are blended and salt is added, to improve metallurgical performance in terms of recovery. This change generate impacts in the dump, since the geotechnical parameters are affected; decreasing hydraulic conductivity in about one order of magnitude (explained by the salt added).Changes are shown in the geotechnical parameters of the spent ore, considering that the mining source is the same, and how the operational process and dump design are affected.CITATION:Rimmelin, R and Vergara, C, 2018. Geotechnical behaviour of spent ore – impacts of metallurgical factors, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 369–375 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By Ronald Ticona, Anaani Huaman, Andrea Lucero

Mine-to-mill optimization begins with a clear understanding and ongoing assessment of blasting, crushing, and grinding operations. Modification of blasting practices to optimize feed size can increase a mine’s throughput. However, this is only an initial step. To optimize the entire process and fully utilize downstream equipment, fragmentation must be measured at critical points along the size reduction circuit

Jan 1, 2019

By Stevenson BG

The relevance of ore-dressing mineralogical investigations to developing and improving metallurgical flow-sheets is discussed and examples are given of the application of such studies to various types of ores and mill products (Au, Cu-Sn, Ni and Sn). The mineralogical investigations described illustrate (a) assessment of the feasibility of ore pre-concentration by heavy-media cyclone separation, (b) evaluation of the potential applicability of various metallurgical treatment processes to an ore, and (c) characterization of mill products to assess circuit efficiency and to guide circuit modifications.

Jan 1, 1978

The development of the Moura Coal Preparation Plant is described, commencing with the first'stage of the plant commissioned in 1963. The subsequent expansion stages are traced through to October, 1973. The plant has undergone frequent stages of expansion and modification and this process is continuing. The development programme for 1974 is described as proposed in late 1973. The characteristics of the Moura and Kianga field coal seams with respect to washability are summarised and some comment is made on the blending of these coals prior to washing, to ensure production of export grade coal within specification.

Jan 1, 1974

By Lays Augusta Leal Carvalho, Alex Milton Albergaria Campos, Paulo Santos Assis

A presente pesquisa dedica-se a analisar a adição de biomassa de serragem, que é uma matéria-prima carbonosa que pode ser utilizada nas misturas de carvão para produção do coque metalúrgico, preservando a qualidade exigida, com menor custo. A qualidade do coque metalúrgico pode ser determinada por meio da efetividade das suas funções químicas, físicas e térmicas no interior do alto-forno. Para produção de ferro gusa, qualquer modificação nos constituintes das matérias-primas pode ter influência direta na produtividade do alto-forno e na qualidade final do aço. A partir das análises de degradação térmica como reatividade do coque (CRI) e resistência do coque após reação (CSR), resistência a frio (DI) e análises imediatas, pode-se definir a qualidade do coque metalúrgico produzido com serragem. Assim sendo, o objetivo é relacionar estes parâmetros com as particularidades do material e suas funções no alto-forno. Os resultados mostram que tecnicamente é viável a utilização de até 2% de serragem de eucalipto na mistura de carvões.

Oct 1, 2019

By Bruce I. Thomas

As a part of the United States Department of the Interior program for developing natural resources in Alaska, the Bureau of Mines studied the tin-bearing gold-placer deposits in the Tofty area of the Hot Springs district in central Alaska. The principal objective of the Bureau's work was to obtain facts about the extent and character of the placer deposits (including tailing) to indicate the economic or strategic tin-production potential of the Tofty "tin belt." A secondary objective was to determine (if possible) the bedrock Source of the cassiterite and other minerals found in the placer deposits. The placer phase of the work was begun in July 1954 and was continued during the 1955 and 1956 field seasons. Extensions to, and connections between, known placer channels were sought by 82 churn-drill holes. The Bureau drilling did not expand the placer deposits beyond the limits established by drift-mining operations and by previous drilling done by private concerns.

Jan 1, 1957

By G Morgan, C Kemp

In December 2010, a trial of borehole radar technology was conducted to test the usefulness of the technique in better refining the position and geometry of narrow vein orebodies away from the primary data sources of drilling and mapping of development excavations. This paper summarises the reasons why the technique was applied, describes the testing methods selected and summarises the outcomes of the trial.Poor reconciliations of recovered metal from a section of an orebody at Jundee mine site, Western Australia, led to an investigation that identified insufficient understanding of the geometry of a narrow vein orebody as a potential cause. This orebody was situated between mapped development excavations and away from surrounding drill holes. Borehole radar was identified as a possible technique that could supply information on vein location and continuity away from other data sources allowing more accurate orebody modelling and subsequent stope optimisation.A borehole radar instrument (10 - 100 MHz frequency) was inserted into pairs of purpose-drilled boreholes on either side of relatively well-constrained mineralisation and the radar reflection data was collected. This process was repeated in five locations across the mine to represent the most common geological settings, lithologies and orebody varieties encountered at Jundee to determine the suitability of applying the technique in each of these settings. Collected, processed and interpreted radar data was compared to other geology data collected independently for verification and interpretation.Conclusions drawn from the analysis were that the technique could effectively determine the following features of the mineralised veins in the majority of test environments: geometry of veins, magnitude of offsets where structures intersect and orientations of planar structures with short strike length. The technique was very useful in selecting the appropriate structural interpretation where available data could lead to multiple, equally likely, interpretations.CITATION:Kemp, C and Morgan, G, 2012. Using borehole radar to refine orebody interpretations in a narrow vein gold deposit, in Proceedings Narrow Vein Mining 2012 , pp 121-130 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By Joseph Javes Aramburú

El presente texto describe la optimización del circuito de molienda y clasificación de la planta de hierro, el cual comprende un molino de barras y de bolas. El proceso se inicia con la exploración geológica, se determinan las reservas probadas y probables, y se establece la forma de explotarloLa eficiencia de la molienda está en función del volumen útil del molino a diferentes volúmenes de llenado que permite determinar los parámetros óptimos de la operación.

Apr 1, 2013

By Rafael Abreu Fraga

Este trabalho tem como objetivo apresentar a nova linha de Laminação de Chapas Grossas da Usina de Ouro Branco da Gerdau, marcando a entrada da empresa na produção de chapas grossas de alto valor agregado no Brasil. A primeira fase do projeto consiste de um forno de reaquecimento de placas, um laminador de chapas grossas, sistema de resfriamento acelerado – Mulpic®, desempandeiras a quente e a frio e uma completa linha de acabamento constituída de linha de tesouras, oxi corte e máquina de ultra som. Neste projeto estão empregadas as mais modernas tecnologias para garantir a qualidade do produto: automação completa dos equipamentos com modelos matemáticos de controle do processo, sistema HAGC, Work Roll Bending e Work Roll Shiftting Smart Crown®. A nova linha tem capacidade de produção de 1,2 milhões de toneladas por ano na primeira fase, podendo alcançar 1,8 milhões de toneladas na segunda fase com espessura variando entre 6,0 a 150 mm e largura entre 900 a 3700 mm.

Aug 17, 2017

By David Schlain

A small alumina reduction cell with a graphite crucible and boron nitride liner was developed by the Bureau of Mines as the initial phase of a study of the reactions which occur in the reduction of alumina by the Hall-Heroult process. Operating conditions in the cell such as temperature, time, current density, electrolyte composition, and electrode materials may be varied easily. Aluminum was produced in the cell at a current efficiency of about 75 percent and a cell voltage of 2.7 volts. Although the data are not wholly conclusive, the operation of the cell did not appear to be greatly affected by large changes in temperature, electrode spacing, current density, and alumina concentration in the electrolyte.

Jan 1, 1963

By LEE H. CORNELL

Drilling activity in Kansas during 1945 continued at an accelerated pace to meet the demands of war; 1810 tests were drilled as compared with 1856 tests the previous year, 1771 tests in 1943, and 1516 tests in 1942. During the year 31 new oil pools and 10 new gas pools were discovered. Of a total of 364 wildcats drilled, 323 were dry; and of 1446 tests drilled in pools, 825 were oil wells, 197 gas wells, and 425 dry holes.

Jan 1, 1946

By C. G. McLaughlan

The Noranda concentrator was placed in operation in October, 1928, and the object of this paper is to outline operations during the twelve months which have elapsed since that time. The ores milled are massive sulphides carrying copper and gold, and, in certain cases, zinc. These ores have a specific gravity of about 3.8. The average assay of the copper-gold ore so far treated has been 2.0 - 3.5 percent Cu; 0.10 - 0.20 oz. Au; 40 - 51 percent Fe; and 6 - 15 percent SiO2. In this ore the copper occurs almost entirely as chalcopyrite, and the iron which is not combined with the copper is present mainly as pyrite and pyrrhotite. ?some iron is also combined with the silica, the ratio being about 1 to 4, and a small percentage is present as magnetite. The occurrence of the gold has been shown by microscopic work carried out by Prof. L. C. Graton, of Harvard University, to be very variable. Some of it is free, and is included within the base-metal sulphides or occurs at their boundaries. A similar distribution also holds for a portion of the gold which is combined as a telluride. Little is so far known of the occurrence of the silver other than that some of it may be combined with the gold in the telluride, petzite. The copper-zinc ore contains up to 6 percent copper, and has a very variable zinc content. The copper in such ore is present as chalcopyrite, and the zinc as sphalerite. In starting the mill we had three conditions to face; the first of these was climatic, the second was the lack of skilled flotation operators, and the third was the ore itself." The last of these three proved much more difficult to contend with than the other two combined.

Jan 1, 1930

Constraints on the mineral industry are best treated as issues that have to be understood and managed in partnership rather than in conflict with communities. The Zapopan development at Mt Todd in Australia and the Martha Hill development at Waihi in New Zealand are but two of many recent successful examples at the local level. However, at the national level, the issues are more complex and more difficult to resolve because the most influential stakeholders are now the urban electorates and governments defer to their perceptions when making decisions and policy.

Jan 1, 1995