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By A. A. El-Midany

Traditionally, the choice amongst different upgrading techniques or in finding the optimum operating conditions for a given upgrading technology depends on whether one is looking at the grade or the recovery of the valuable mineral in the concentrate. In fact, the conclusions are not usually the same. This is because the best technique or optimum operating conditions for the highest grade are not the same as the conditions to achieve the maxi-mum recovery. Therefore, a unique measure that takes into consideration both grade and recovery is urgently needed. Finding such a measure is the objective of this paper. A proposed measure provides a selectivity index in the range of 0 to 1, where 0 is no selectivity and 1 is ideal selectivity. The index can be obtained by plotting the so-called Fuerstenau upgrading curve, which relates the recoveries of the components in products of separation and a running regression applying a one-parameter equation. The measure was applied to assess the selectivity of selective flocculation under different operating conditions when used as a sensitive upgrading technique for ultrafine ground ores. After applying the proposed selectivity measure in the case of the selective flocculation of ultrafine Egyptian iron ore without the addition of cations, it was found that the optimum conditions are pH 11, 1 kg/t sodium silicate and 0.4 kg/t potato starch with a selectivity index of 0.55. With the addition of cations, the optimum conditions were found to be pH 11, 1 kg/t sodium silicate and 2 kg/t potato starch with a selectivity index of 0.65. It should be noted that determining these optimum conditions using the traditional grade or recovery measures was highly ambiguous.

Jan 1, 2008

By H. Möhle

Premier Mine is a large underground diamond mine, situated at Cullinan in the Gauteng Province of South Africa. The mine hoists over 3 millions tons of diamond bearing kimberlite per year, from a modern, mechanized panel retreat block cave mining operation. Troughs sited at the base of the cave are developed into the overlying caved ore, allowing loading access to the ore through draw points. Trough opening is therefore a vital aspect of the mining operation. Most of the production is dependent on fast, reliable and safe trough opening. Successful trough openings are achieved under difficult mining conditions due to restricted void, long up-holes and the inherent properties of kimberlite?soft, elastic rock with a high swell factor. Early in 1998, Premier Mine undertook a joint development project (with an electronic initiation system supplier) to determine whether the use of a fully programmable electronic detonator system would enhance the mining cycle in the trough opening process. Blasting commenced in February 1998, initially with blasts of a similar size and duration to those that had been previously blasted with shock-tube systems, to confirm the operational capabilities of the blasting system. The accuracy, reliability and flexibility of the electronic delay detonators (EDDs) minimized associated risks for re-engineering of the trough opening process. Further, as blast timing was optimized, larger blasts were successfully initiated. To date over 20 troughs have been opened successfully with the use of EDDs. Not only did it take less time to open troughs, but also drilling and blasting operations have been optimized, as well as an overall improvement in safety. This paper details the benefits that EDDs have delivered to Premier Mine in this area. The logic followed is: ?Review of the original trough opening practices ?Re-engineering of the trough opening process ?Implementation of EDDs ?Evaluation of improvements and conclusions.

Jan 1, 2000

By M. Hopf

The use of water-cooled copper components as sidewall elements of submerged arc furnaces and other pyrometallurgical applications has become increasingly common. The high cooling efficiency of copper has made it possible to increase the service life of furnace refractories when compared to conventional refractory linings. However, even the self-healing effect of ?freezing? worn areas of the lining does not necessarily protect the copper coolers against wear or corrosion completely. In order to avoid furnace explosions, various methods have been used to monitor the wear of coolers. Unfortunately, these have not been able consistently to identify localized wear. Thos Begbie (South African) and SAVEWAY (German) jointly developed technology to embed a line sensor into the copper cooler during the casting process. This system allows an exhaustive monitoring of the copper cooler. A SAVELINE sensor is placed inside the copper-cooling panel between the water-cooling passage and the hot face of the panel. The sensor follows the meandering shape of the cooling water channels. In the first instance, the sensor provides analogue information as the thickness of the copper reduces. Secondly, this wear signal will be confirmed by a signal of interruption if the sensor is washed away. Because of the structure of the sensor, a self-diagnosis is possible and indications can be confirmed (double proofed).Subsequent to the manufacture of some test pieces, coolers for a large submerged arc furnace were manufactured. The sensorized coolers have been installed at the intermittent surface (slag line) where the largest amount of corrosion has been encountered. The system has been operating since December 2005 in what is considered one of the largest submerged arc furnaces in South Africa. Keywords: Pyrometallurgy, furnace, copper coolers, freeze lining, monitoring, Saveway

Jan 1, 2006

By Nicholas R. Dixon

This report summarizes all work performed under Phases I, II and III of U.S. Bureau of Mines Contract H0387006, "Development of a Prototype Retrofit Noise Control Treatment for Jumbo Drills." The noise and vibration levels of four jumbo drills were characterized and a survey of percussive rock drill usage is reported. A Gardner-Denver DH 123 drill was chosen as a demonstration drill, and extensive noise diagnostic studies were performed. Noise control treatments were designed, developed and evaluated in a reverberant drill test facility. The treatments consisted of an integral enclosure/muffler for the drifter, vibration isolation of the drifter from the enclosure and feed, and a drill steel sheath. A 19 dBA reduction in overall sound power level was achieved with no loss in drilling rate. The prototype retrofit treatments were field tested in an aboveground mine and in a production section of an underground zinc mine. Long-term durability and operator acceptance of the enclosure/muffler treatment were excellent. Preliminary evaluation of the drill steel sheath was encouraging, although additional testing is required.

Jan 1, 1982

By Thiago de Souza Amaral

Os aços de alta resistência microligados ao nióbio tem se demonstrado uma solução ótima na fabricação de aços para utilização em perfis estruturais utilizando os conceitos já desenvolvidos para a indústria de gás e óleo. O nióbio com seu efeito refinador de grãos, com redução da temperatura de transformação entre austenitaferrita, endurecimento por precipitação e retardamento da recristalização da austenita, usado em equilíbrio com titânio, manganês e silício e os novos processos de produção com resfriamento controlado torna possível a obtenção de aços com microestrutura bainítica, baixo carbono e alta resistência mecânica. Este trabalho demonstra os pontos de destaque referentes ao projeto de estruturas utilizando estes aços, bem como uma avaliação quanto ao processo de soldagem durante a fabricação das mesmas. É possível evidenciar que a estrutura final se torna ideal para aplicação em diversos ambientes devido a sua baixa temperatura de transição dúctil-frágil, produção de uma estrutura com cerca de 10% a menos em peso, 5% a menos em custo e com excelente soldabilidade.

Aug 17, 2017

By Daniel Palacios N

El proceso de industrialización del Perú se rige por la demanda de materias primas minerales, para las cuales se exigirá una óptima calidad y precios competitivos. Para contrarrestar esta demanda, es necesario el manejo adecuado del aprovechamiento de los recursos minerales naturales en los yacimientos mineros y así valorar las disponibillidades de los mismos a escala nacional. En este sentido, el objetivo del texto describe la aplicación del programa de no-metálicos que el Departamento del mismo programa INGEMMET propuso.

Oct 14, 1980

The dissolution of gold in cyanide has been studied, using both chemical and electrochemical techniques. The electro-chemical studies have confirmed that gold may become passive in cyanide solution if its potential becomes more positive than -O· 5 V v. saturated calomel electrode (S.C.E.). The results of the conventional solution rate tests suggest that, although the solution rate is controlled by the rate of diffusion of oxygen at low oxygen and agitation levels, when these are increased the gold may become passive and its solution rate approach a steady value, or even decrease with increasing oxygen level. The passivity of gold has been shown to be of importance in the solution of small spheres of this metal, and in the extraction of gold from a calcined auriferous pyrite concentrate.INTRODUCTIONAlthough it has been appreciated for many years (McLaurin, 1893, 1895) that dissolved oxygen is a necessary adjunct to the solution of gold by the cyanide process, attempts to quantitatively assess its effect have led to conflicting results. For example, Barsky, Swainson, and Hedley (1934) reported that an increase in oxygen concentration improved the solution rate, but Beyers (1936) claimed that such an increase would reduce the rate at which the gold dissolved.By using an electrochemical approach Kudryk and Kellogg (1954) showed that the diffusion rate of either the cyanide or the oxygen was a controlling factor, and that, if the mole ratio of cyanide to oxygen concentration was greater than 10, the solution rate was proportional to oxygen concentration.These results, although they represent some of the most careful work available, were in direct contradiction to the findings of Mills (1951), who found that gold may become passive in cyanide solution, with a resultant decrease in solution rate.

Jan 1, 1963

By R. Schulz, K. King

Concentrating Line 6 just went down again. The control room operator checks the graphic display. Only one piece of equipment shows an alarm. Clicking on the ball mill icon, he discovers the culprit was the low flow lube switch. The flow looks okay now, but it is the third time this week the switch has stopped the line. Maintenance is called, the switch replaced and the line is up running again. Sending the right person to the right spot immediately can save hundreds of hours of downtime every year. This paper discusses the principles behind implementing smart First-Out Fault Detection to dramatically reduce equipment downtime in new, or existing control system architectures. Methodologies are presented to maximize the system benefits, while minimizing development costs. Case histories are presented for a number of successful implementations in mineral processing plants.

Jan 1, 2001

By Collin L. Stewart

The high cost and limited flexibility of modern longwall systems has resulted in the need for mine engineers and geologists to predict possible adverse mining areas ahead of mining and to then design and implement suitable ground control solutions in a timely and cost effective manner. Therefore, over the last 30 years, geo-technical evaluations for coal mine planning and development have advanced from a minor afterthought to an important part of today?s successful, high capacity, longwall mining operations. The latest iteration in this progression of improved analysis for predicting future mining conditions is a computer-based Stability Mapping System developed by West Virginia University. This system is designed to allow the mining engineer and geologist to effectively combine the mine geologic characteristics, stress influences, and structural features into an integrated stability map for use in mine planning and support design. This paper details the application of the stability mapping system to Bowie Resources, LLC, Bowie No. 3, multiple-seam longwall coal mine. At this mine, the prediction of adverse mining conditions using the stability mapping system allowed management to accurately adjust their support densities and operational procedures, and to successfully mine through difficult conditions safely and successfully.

Jan 1, 2006

By Letícia Miranda Alves

Os pós fluxantes têm como base o sistema CaO-SiO2-Al2O3-Na2O-CaF2 sendo que, em alguns casos, podem conter também MgO, Li2O, K2O e B2O3. Os resíduos de mármore e granito, oriundos dos processos de produção de rochas ornamentais, são passivos ambientais na região sudeste, sobretudo no estado do Espírito Santo. As composições destes resíduos são similares a dos pós fluxantes utilizados nos processos de lingotamento contínuo e portanto serão utilizados neste trabalho para formulação de novos fluxantes. Uma mistura de granito, pó de mármore e adições foi realizada com o objetivo de produzir um fluxante similar aos comerciais encontrados no mercado. O novo fluxante foi caracterizado por difração de Raios X antes e depois de passar pelo teste de susceptibilidade de formação de fases cristalinas ou “teste de Stollberg” modificado. Os resultados mostraram que existe a formação de fases similares às observadas em fluxantes comerciais. Avanços nesta área podem viabilizar economia de matéria-prima e a diminuição do impacto ambiental causado pelo mercado de rochas.

Aug 17, 2017

By M. S. Klima, A. Simard, M. L. Turek

Laboratory testing was carried out to evaluate several devices for recovering clean coal from bituminous coal refuse material. The bulk of the testing focused on using a dense-medium cyclone to process -0.6-mm refuse material. A hindered-settling column and a spiral concentrator were also used to process 1.2x0.15-mm material. Product yields and ash contents were obtained for all tests, while partition curves were generated for selected tests from which the characteristic performance parameters (relative density of separation and probable error) were determined. The results indicated that the dense-medium cyclone was capable of cleaning down to 0.037 mm, while the other devices were effective to 0.15 mm.

Jan 1, 2002

By Guilherme Santos Garcia

Este trabalho tem por objetivo avaliar a sinterização a plasma do alumínio com a utilização da técnica Active Screen, em comparação com o processo em forno resistivo. Foi utilizado pó de alumínio atomizado, com granulometria entre 30 e 100µm, sendo misturado junto aos pós cerca de 1% em massa de estearato de zinco como agente lubrificante. Foram confeccionados corpos de prova com 13mm de diâmetro e 10mm de altura. A compressão dos pós se deu através de uma prensa hidráulica, de ação simples, utilizando pressão de compactação de 600MPa. O tempo te sinterização foi mantido em 60min a temperatura de 500ºC, utilizando atmosfera de nitrogênio. Foram realizadas medidas de densificação, antes e após a sinterização, medição de rugosidade e microdureza superficial, bem como análises em MEV da superfície das amostras. O processo a plasma se mostrou satisfatório, sendo capaz de produzir amostras com boa densificação. As medições de microdureza superficial evidenciaram valores semelhantes entre os processos, sendo a amostra sinterizada via plasma a apresentar menor variação de microdureza. Através da análise de EDS das imagens, foi identificada a presença de estearato de zinco em ambos os processos, evidenciado que a extração do lubrificante não foi totalmente eficaz. Ainda, houve uma leve redução da rugosidade no processo a plasma em relação ao convencional.

Aug 17, 2017

By Andrew P. Schissler

The Citronen Zinc-Lead Project is one of the world?s largest undeveloped zinc-lead resources, containing more than 13 billion pounds of zinc and lead metal. The project is located in northern Greenland, a self-governed region of the Kingdom of Denmark (Figure 1). Citronen is the northern-most mine in the world, operating at a latitude of 83o 3? N. In excess of 67,000 meters of diamond drilling have been completed to delineate the resource. As of January 2012, the measured, indicated, and inferred reserves for the Citronen project totaled 70.8 million tonnes, consisting of 5.7% zinc + lead (3.5% zinc cut-off) (Ironbark, 2012). For the underground mine plan, room-and-pillar and long holestoping mining methods were selected. The beneficial application of structural fill was considered for increased recovery, efficient tailings disposal, and ground control. Three types of fill were compared - paste fill, cemented rock fill, and iced tailings. An environmental and economic feasibility study concluded that iced tailings was the preferred alternative provided it met the ground control requirements. The purpose of this paper is to explain the investigatory steps that led to the possibility for the use of iced tailings as structural fi

Jan 1, 2012

By Silvio Hernández Aquije

El presente artículo señala el plan de exploración e inventario del vanadio en el Perú. El vanadio de depósitos industriales se ha encontrado en los carbones denominados asfaltitas que se hallan repartidos a todo lo largo de la rama occidental de la cordillera de los Andes. Sin embargo, no se le ha encontrado en otras fuentes comerciales como es el caso de los vanadatos del tipo de la vanadinita. En ese sentido, el autor plantea una exploración con sonda diamantina en los filones vanadíferos de la Región Central de la Cordillera de los Andes, ya que se puede adaptar a todas las condiciones que puedan presentarse en el terreno. Para ello, se trabajará sobre una área en la que hay seguridad da encontrcrar buenos filones de asfatitas vanadíferas.

May 1, 1954

By John C. Stankus

To improve mine roof bolt performance, Jennmar Corporation commenced the design and development of a new roof control sys- tem. This new system designated "Insta'l Compression", not only improves safety, but is more cost efficient due to reduced amounts of resin needed per bolt installation. In this paper the research and development of this new system will be outlined. Much of the information presented will be actual test data from various underground operations in Alabama, Kentucky, and Pennsylvania. The development of this system will also cover the design of a new expansion shell, resin compression ring, anti- friction washer, and upgrading of material specifications.

Jan 1, 1990

By Thomas P. Dolley

Building stone, cassiterite, kaolin, gold, lime, and peat were the only commodities mined, The country's main economy was in agriculture, primarily in coffee exports. Tribal violence occurred again, between the Hutu and Tutsi tribes, causing an estimated 50,000 deaths, mainly in rural and mining areas. The inflation and a large deficit continued. The country continued to import cement, fertilizers, oil, and petroleum products. Burundi possessed numerous small gold deposits. The northwest and north-east were the country's two most important gold-bearing regions. A large kaolin deposit was found at Ngozi, and its mining was specified in the fifth 5-year development plan for 1988-1992. In the area of Rugombo, limestone was being explored with the intention of opening a cement plant.

Jan 1, 1990

The small-scale surface mining operation in northern regions is typically located in a remote, ungaged basin. With the recent increase in the economic potential of mining, the number of small operations is increasing. The year-to-year variability in precipitation in this region under study is of great concern to mine operators. Some years may yield only 5 to 6 inches of precipitation, while others may yield in excess of 15 inches. Such variability makes placer mining operations difficult to plan, since low water years may result in too little run-off for gravel washing and high water years may result in flooding of mining developments. There are no official streamfloaw records in many watersheds in the northern region containing placer mining claims. However, information from other streams permits calculation of an estimated discharge for a watershed under consideration using average flows per square mile of drainage. It is to be emphasized that these are average or expected figures in reality, one water year may be significantly wetter or drier than another. This high variability of annual precipitation is significant in relation to placer operations because of the large quantities of water required for this type of mining. Some operations can not operate in low water years. In the larger watersheds, operations may continue in low water years but at a slower pace because of longer water collecting times. The high variability of available run-off rakes placer mining in many parts of Alaska difficult to plan on a long range because of the unpredictability of water supplies.

Jan 1, 1985

By J. H. East, D. Harrington

"INTRODUCTION Considerable interest has been shown in the prospective use of Diesel-powered haulage equipment in both coal and non-coal mines. Foreign technical magazines have devoted considerable space to discussions of the use of Diesel locomotives in European mines and some mention of it has been made in technical papers in the United States. The Bureau of Mines has extensively tested the gases produced in the exhaust of the Diesel engine under various atmospheres and conditions of use; it has established a schedule of tests for permissibility of Diesel engines for use in underground coal mines, including, gassy or dusty mines.This publication provides information as to the successful use of Diesel-powered equipment underground workings in the United States and Europe, briefly discusses the characteristics of some of the toxic gases found in the exhaust of Diesel engines, and points out that Diesel-powered equipment can be used with reasonable safety in underground minus if necessary and entirely feasible precautions are taken."

Apr 1, 1947

By A. Boniface

The International Tunnel and Underground Space Association (ITA) has a number of working groups (WG) that meet at least once a year. One of these is WG12, ?Use of Shotcrete?, of which the author is a member. The purpose of this paper is to draw attention to a number of topics that were discussed at the WG12 meetings held in April and September 2008; and also to a number of other matters that arose from the presentation of thirty-four papers at the 5th International Symposium on Sprayed Concrete held in Lillehammer, Norway between 21 and 24 April 2008.

Jan 1, 2008

By James R. Kerr

This study reviews the sulfur and suliuric acid industries in Eastern United States with emphasis on patterns of consumption and marketing. Output of sulfur in the East is relatively small, and most of the area's sulfur requirements are met by gulf coast Frasch sulfur. Over the long ten recovered elemental sulfur from sour natural gas and petroleum may become the East's major source of sulfur. In 1958 sulfuric acid manufacture consumed over 80 percent of the area's sulfur requirements. The leading uses for sulfuric acid were the manufacture of superphosphates and chemicals. Over the years, unit requirements for sulfur and acid in many major markets have been reduced through improved technology, but new markets always have been developed to keep the industry vital and growing.

Jan 1, 1965