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Electro-Flotation Research on Fine Cassiterite

Sep 13, 2010

By U. Thorley

Management of mine and tailings reclamation activities by surface mining oil sands operations in Alberta, Canada is experiencing increased national and international attention. Of particular concern is the ability of existing mines to execute and fund reclamation activities. Concern stems from a lack of demonstrated tailings reclamation technologies, perceptions of a poor track-record of reclamation activity by industry, and a lack of transparency with respect to the potential cost of reclamation activities relative to the monies secured in Alberta?s Environmental Protection Security Fund (EPSF). Limited information is publicly available regarding reclamation costs and technologies. Available data typically comes from disparate sources. This paper examines the expected costs of oil sands reclamation activities through a study of corporate Asset Retirement Obligation (ARO) liabilities, the Province of Alberta?sEPSF, and published data relating to reclamation costs.Issues relating to current liability funding are introduced.

Jan 1, 2011

By Jian Li, Tiejun Chun, Jian Pan, Deqing Zhu, Vinicius Mendes

"A study of the coal-based direct reduction behaviors of composite binder magnetite pellets was carried out in a simulating coal-based grate-rotary kiln process. It is shown that preheated pellets possess much better reducibility than fired oxide pellets: 40 min are required for preheated pellets to reach over 90% metallization degree compared to 100 min for fired oxide pellets. The compressive strength of preheated pellets decreases dramatically at the earlier stage of reduction, climbs quickly after reducing for 30min and achieves a high value at the end of reduction. However, the compressive strength of metallized pellets from reducing of fired pellets is much lower, more cracks and fractures being formed. In the preheated pellets, crystallite of metal iron is coarse. In the oxide pellet, a large number of interconnected crystals of metal iron are formed inside pellets, and pellet structure is very compact.IntroductionDirectly reduced iron is an excellent feed in electric arc furnace (EAF) steelmaking, and possesses low tramp element content and steady component. It is generally preferred in the production of high quality steel [1-3]. Nearly 64.44 million tons of DRI were produced in 2009 over the world, over 80% of which were produced by gas-based processes, the left by coal-based processes. However, the DRI capacity was only 600 thousand tons in China in 2009. The EAF steel production has exceeded 40 million tons annually, and most of EAF operate on hot metal as feed [4]."

Jan 1, 2011

By S. G. Malghan

This paper describes uses of sodium sulfide in the flotation of oxide and sulfide minerals of copper, lead, and zinc. The activation and depression effects of sodium sulfide are of particular importance because of their applications with oxidized lead and copper ores. In spite of its industrial importance; however, the nature of the heterogenious reactions between sulfide ions in solution and the surface of oxidized minerals has not been fully understood. Hence, proposed mechanisms of the sulfide action in flotation, methods of measuring and monitoring of sodium sulfide in flotation pulps, and variables influencing the sulfide addition are analyzed. A review of recent studies shows that sodium sulfide addition to flotation pulps can be monitored and hence the optimum dosage controlled using the platinum and/or sulfide specific ion electrodes. The use of these electrodes for improved reproducibility of bench-scale experimental data and plant implementation of laboratory results is described.

Jan 1, 1985

Map

Jan 1, 1939

By R. M. Whyte

The complexities that exist in the nature of the basic feedstock to the metallurgical process call for a high degree of ingenuity from the extractive metallurgist in seeking the best possible treatment method for a particular ore. Drawing from personal experience the author presents four case studies that demonstrate the value of creative thinking in addressing the challenges typically encountered by the extraction metallurgist. It is concluded that creative expression most often occurs in response to a perceived strong need within an organization. By deliberately laying down meaningful challenges management can stimulate innovative thinking and achieve extraordinary results.

Jan 1, 2009

By I. R. Firth, D. L. Taylor

Metal mining operations, in particular gold mining operations, use intensive ore control procedures in order to manage the extraction of ore zones from benches containing both ore and waste material. Typical grade control procedures rely on blast hole samples to indicate ore grade. Statistical techniques and geological controls are then used to create two-dimensional polygons, which indicate zones of material designated as ore. These ore-polygons are calculated using pre-blast material locations and are generally not corrected for rock movement caused by blasting. This lack of correction appears to exacerbate the material mischaracterization problem of sending ore to the waste dump and/or waste to the mill. One Nevada gold mining company has estimated that this could be a $10 million per year problem for their operations. Using a simplified vector field algorithm, a method of taking point movement data and interpolating post-blast positions for all nodes in a polygon has been developed. Currently working in 2-dimentions (X-Y), this algorithm utilizes the movement vectors calculated from pre-and post-blast positions of targets placed in a blast, to generate a spatial transformation function for any point on the bench. This transformation is then applied to the nodes of the ore-polygons to produce modified dig lines ore polygons reflecting distortion and movement resulting from the blast. The method as implemented uses common mine planning routines and is performed using the Surpac software suite. The method may be adapted to use any pre-and post-blast point movement data available, and most mine planning suites include the simple interpolation algorithms used. Keywords: Blast movement; Ore control; Open pit blasting; Grade control

Jan 1, 2003

By Bart Bartholomew, Randall J. Essex

INTRODUCTION In June of 2004, at the North American Tunneling Conference in Atlanta, an all-day workshop was conducted to review the application of Geotechnical Baseline Reports (GBRs) for underground construction. The moderator for the program was Bart Bartholomew, former President of Fruin Colnon Construction Company. The program involved commentary by a panel of engineers, owners, contractors, and legal representatives within the North American tunneling industry, as well as an extended audience discussion. The panelists were: Peter Douglass, President, Peter Douglass, Inc. Randall Essex, Executive Vice President, Hatch Mott MacDonald Joseph Gildner, Deputy Director for Technical Services, Sound Transit Randall Hafer, Esq., Kilpatrick Stockton Robert Fitzgerald Esq., Watt, Tieder, Hoffer, & Fitzgerald Kirk Samuelson, Senior Vice President, Kiewit Construction Group DEVELOPMENT OF PROGRAM FORMAT The focus of the program was to assess the state of the practice in the preparation of GBRs, and to discuss improvements that could and should be made with regard to their preparation, interpretation, and application. The approach used to achieve this focus in the broadest possible way was unique, in that it involved the panelists’ preparation of the workshop format and materials months before the presentation of the workshop. First, each of the six panelists was selected by the moderator based on their reputation and involvement in their respective fields of expertise, taking care to maintain balance and contrast within the collective pool of talent assembled. Following selection and agreement to serve on the panel, each panelist was asked to independently submit to the moderator a list of the six most pressing issues involving GBRs that they each frequently encountered in their individual professional experience. Each was asked to rank their issues in descending order of perceived importance. This process resulting in a pool of thirty-six potential or “candidate” issues for use in the workshop program. Contrary to the moderator’s expectations, there was surprisingly little duplication among the thirty-six issues submitted.

Jan 1, 2005

By L. Gonzalez-Sardi, W. McCombe, M. Pearson

Pressure oxidation is increasingly being used for processing refractory sulphide ores and concentrates because it offers highly effective base metal and precious metal extraction while minimizing elemental sulphur, arsenic & mercury emissions. Yet pressure oxidation processes introduce new safety concerns and process risks as demonstrated by a number of safety incidents over the last 20 years, including overfilling, oxygen-metal fires, nozzle/sparger failures, and uncontrolled pressure relief events. Chemical Process Safety regulations in the United States and Canada mandate that companies constructing or operating chemical process facilities perform a rigorous hazard and risk analysis based on either ANSI/ISA-84.00.01 or IEC 61511 safety standards to determine the level of protection required for each hazard in the plant. This paper describes the application and implementation of three (3) unique safety instrumented systems developed by Hatch for ensuring the safe operation of three different pressure oxidation processes.

Jan 1, 2014

By D. A. Reynolds, J. D. Davis

"INTRODUDTION Investigations by the Bureau of Mines have shown that the carbonizing properties of splint and bright coals may differ greatly. In a study of 55 coal columns selected from representative coals of the Appalachian region, Sprunk and coworkers 10/ compared various chemical and physical properties of splint and associated bright coals. Carbonization tests in the Fischer retort at 932°F. (500°C.) showed that, except for bright coals of high oxygen content, the coke residue from bright coal was much more swollen and cellular than that from splint. ·with one exception, agglutinating values determined by the Bureau of Mines test, were lower for splint than for associated bright coal.Because sorting of coal in quantity is tedious and time-consuming, separate types have not been carbonized by the Bureau of Mines-American Gas Association (BM-AGA) test, which requires 85- to 200 pound charges. However, this method has been used to determine the carbonizing properties of samples 0f bed layers that are composed largely of either splint or bright coal.4/ In these earlier tests, which were made at high temperatures on layer samples from the Elkhorn bed, Letcher County, Ky., the splint coal yielded more coke than the bright coal, and this coke was slightly stronger than that from the bright coal. The cokes from samples with large proportions of bright coal were more cellular or porous, as were the low-temperature cokes obtained from carbonization of separated samples of bright coal in the Fischer retort."

Apr 1, 1944

By G. France

The Blair Athol Coal Mine (BAC) is a large open cut operation in the Bowen Basin of Queensland, Australia. Current mine capacity is about 11 million tonnes per annum(Mtpa) of export coal. On-line analysis at BAC consists of two Coalscan 9500s installed directly on the output of the crusher plant and immediately before the product stockpiles, while a third Coalscan 9500 is installed on the transfer conveyor feeding the train loading bin. The two product Coalscans have a dual purpose. The first is to provide real time coal quality data directly back to the mining operations. The second is that of modeling the product stockpile with accurate on-line information. This modeling enables both production and coal quality personnel to accurately examine the coal quality of each stockpile with a degree of resolution which previously had never been achieved.

Jan 1, 1999

By B. Cavender

Safety departments have traditionally been held responsible for the safety performance of their division or company. This approach leads to a lack of ownership of safety issues by the larger organization. An alternative paradigm is significantly more effective: the members of the work force (managers as well as workers) are fully responsible and accountable for safe production. The safety department is not extinct, however. Its role has changed, to focus on training, litigation, and external relationships such as community relations. This approach was implemented at BHP Copper's Superior mine and mill in Arizona. By obtaining the genuine commitment of the work force to accident-free production, the mill's MSHA incident rate immediately dropped from 7.4 to zero. The mill also ran one year with no MSHA citations. When this philosophy was implemented at the divisional level, the division's incident rate decreased from 9.5 to 1.1,an 88-percent reduction in six months.

Jan 1, 2000

By C. A. Rawlins

In an underground mine the ingress of heat can generally be attributed to two sources (Rock exposure and artificial mechanisms). The heat load relating rock exposure is subdivided into stoping [~40%] and haulages [~20%]. Rock is exposed to the ambient air and as a mine increases in depth the VRT (Virgin Rock Temperature) increases which leads to more heat ingress underground. To counter the heat ingress, especially in low-seam stoping areas of a deep level mine, air is, a) cooled artificially, b) the amount of rock exposed is reduced in the back areas of a stope by backfill applications, and c) ventilation air is used more efficiently. The heat reduction within a stope due to placed backfill could amount to ~50% for operations mining at a mean rock breaking depth of about 4500 mbc (metres below collar). Unfortunately, due to backfill transport methods, the physical fluid properties and application methods adopted, additional heat is induced into the air. The heat ingress due to backfill application could amount to as much as 25% of the overall in-stope heat load. This heat influx, seen as a negative aspect of backfill operations, is nevertheless overshadowed by the overall in-mine heat load reduction capability of about 20% attainable. The in-stope benefit [~50%] attainable from backfill operations could be increased with the incorporation of a heat exchange (cooling) methodology to offset the additional heat ingress into the surrounding air of a deep underground mine.

Jan 1, 2003

By K. Holmberg, D. Herriot

This paper by Mr Mclvor is yet another contribution to the eternal controversy surrounding the benefits, or otherwise, of high circulating loads in closed circuit grinding. Throughout the paper it is difficult to establish whether the author is referring to effects relating to the mill, classifier, or to the overall circuit. Table 1 is put forward as indicating the advantage of operating at high circulating loads. From the two (it would be interesting to see more) product sizing points provided in each case, the conclusions to be drawn are that cases one and two have very similar size analyses. The third case, however, indicates a much flatter curve, that is to say, higher fines production and a very wide spread of size ranges. If the objective of this circuit is to provide a closely sized product with minimum overground slimes to the downstream process, then it would appear to be the less "efficient" by far. No data is given for product pulp densities either. The term "efficiency" should never be used without a careful and clear definition. In this case, "efficiency" is used to express an apparent percentage reduction in operating work index (Bond) from the measured "standard" at 250% circulat¬ing load operation. The Bond calculation is itself based upon

Jan 1, 1989

By M. J. Ackerman

This study was undertaken to make a comparison between the cost of mining coal under roof bolt and under conventional timber methods of roof support. Studies were made at 14 mines in Pennsylvania, eastern Ohio, and northern and southern West Virginia. At each mine data were obtained for sections of the mine where the physical conditions, mining equipment, and mining systems were similar. Coal, recognized as one of the basic industrial fuels, is very competitive with other fuels, and management, in order to protect and enlarge its market, must be continually alert to find more efficient methods of production. Continuous production of coal is desired by all operators but never obtained. In mechanized mining the performance and production vary with operating time, which can be interrupted by many variable factors, such as condition of the roof, method of roof support, condition of equipment, water, ventilation, power, transportation, efficiency of operating crew, and supervision.

Jan 1, 1961

By Gary P. Sames

The Bureau of Mines recently initiated a study of geologic features that contribute to roof instability in western U.S. underground coal mines. The purpose of the study is to provide information for use in ground control planning and safety hazard reduction in that region, where mining activity has been increasing. Hazardous geologic conditions were surveyed in selected underground coal mines in Utah and Colorado, and both depositional and structural features were identified as potential ground hazards. Although the conditions found do not differ in kind from hazardous geologic conditions in the Eastern United States, they do differ in intensity of occurrence and relative importance. Three depositional features dominate where unstable roof occurs in western underground coal mines: paleochannel deposits, crevasse splay deposits, and flood basin deposits. Three structural features identified as hazardous, but not so widespread or common as the depositional hazards, are faulting, jointing, and igneous intrusions. This survey establishes a foundation for future studies aimed at reducing and preventing ground control accidents in western coal mines.

Jan 1, 1988

Commercialisation of Ni Heap Leaching at Murrin Murrin Operations

Sep 13, 2010

By A. Z. Lang, D. A. Hall

After a brief description of the causes of spontaneous heating and of general preventative methods, a detailed account is given of occurrences of spontaneous heating in the Main Seam (locally known as the 5/4 Seam) at Westoe Colliery. This seam is about 12 feet thick consisting of hands of coal and shale, but only 4 feet 6 inches is worked because of the thickness os strata in water-bearing rocks and the worked section is selected on quality considerations. An advancing longwall face in this seam (2nd South) began to heat after working for six months and ultimately had to be abandoned. By adopting retreating methods and mining narrow panels it has been possible to extract this coal at an excellent rate of productivity. The system of goaf ventilation is important, because the use of a bleed road would have given rise to dangerous conditions in a goaf which of necessity would have contained fallen coal. Preparatory seals were prepared at selected sites so that, if necessary, a panel could be sealed off quickly; these seals are completed as soon as possible (within three weeks) of finishing a panel. A gas sampling system has been instituted which includes daily sampling on the face and in the goaf, and weekly sampling at the stoppings of all completed panels. The coal has now been extracted from this seam for three years without any further difficulties from spontaneous heating.

May 23, 1905

By Mostafa Maazouz, Jeff Blackwood, Mauricio Gordillo, Sang Hoon Lee, Micah Ledoux, Liang Zhang

To meet rising requirements for the low-damage ultra-fine process with the focused ion beam (FIB) in the materials science and semiconductor industry, the advanced ion column and corresponding advanced applications as a solution are developed and demonstrated. Novel high-speed high kV milling, low kV cleaning and imaging capabilities have enabled the creation of impeccable ultra-thin structures such as TEM samples and nanometer scale structures. Minimizing Ga+ induced sample damage is achieved through the optimized final cleaning at 500 eV ion landing energy with the new ion optics, which utilizes close control of the ion dose, beam incidence angle, spot size, pattern algorithm and imaging performance. Newly introduced process solutions achieve the improved process throughput. Initial demonstration is performed on the latest 14 and 10 nm scale FinFET device. Validation of the thinnest <0.8 nm thick ion damage layer on the <7 nm thick lamella structure was confirmed through TEM analysis.

Mar 1, 2017

By C. W. Owings

Available literature published or abstracted in 1953 and 1954 relating to dust prevention and suppression has been summarized and reviewed in this report, and un-published information also is included to outline current practice for those interested in dust control in and around mines, tunnels, and quarries. More and more companies are realizing the value of controlling dust by incorporating suitable methods and devices in the planning stage. In preparation and crushing plants preliminary tests have been made of the fine materials to determine the best type of dust-control equipment to use, and the details of the quantities of air, the number of sprays, the dust-allaying fluids, and the location of hoods or enclosures have been determined in advance. Such planning has paid for itself in more effective control. Similar planning in a tunnel resulted in healthful conditions and low dust concentrations.

Jan 1, 1956