Search Documents

By R. R. Klimpel

Over the last six years, several new commercial families of sulfide mineral collectors have been developed. This paper summarizes some plant data and use experiences gained with each of these product families. The first is a series of products (F-series) based on a chelation mechanism of attachment. The second of these families is a series of products (S-series) based on an electrochemically controlled mechanism of attachment. The major advantage of the F-series collectors is the very high metal recovery capability in complex ores involving Au, Pt, Zn, Ni, and mixed Cu minerals. The major advantages of the S-series collectors are the very high pyrite rejection capability along with reduced lime requirements in Cu/Mo plants.

Jan 1, 1995

By Joel Lööw, Jan Johansson, Lena Abrahamsson

In this study, we try to illustrate what new technology can mean for the individual miner. We formulate the notion of Mining 4.0, where we attempt to create an image of how the future might look from a miner’s perspective and how mining companies might navigate their way to a future that works for all miners. 

By G. Ferrara

To obtain a reliable comparison between conical and cylindrical separatory vessels used in dynamic dense medium separation systems, the following studies were made: (1) study of the swirling flow in conical and cylindrical vessels using laser-Doppler velocimetry (LDV); (2) study of the behaviour of suspensions of magnetite and ferrosilicon in water in both separators. It was found that: (a) the tangential velocity profiles differ in conical and cylindrical vessels: in a conical cyclone free vortex conditions affect the largest part of the vessel, while in a cylindrical vessel, the motion approaches that of a forced vortex, i.e. that of a centrifuge; (b) the conical vessel manifests higher centrifugal acceleration and very strong densifying; the density differential, and hence the density gradient inside the vessel is large; (c) the cylindrical vessel manifests lower centrifugal acceleration and low densifying, i.e. low density differentials, and hence, the density gradient inside the vessel is small; (c) due to greater densifying, the density cut-point in cyclones is higher than the operating medium density, while in cylindrical vessels the density cut-point is closer to the medium density. The results provide an interesting description of the differing behaviour of conical and cylindrical vessels and help explain the differences in performance between the two types of separators.

Jan 1, 1998

By Y. C. Kim

Three rock fracture parameters define three points along empirical cumulative size (of rock fragments) distribution curves at Inspiration copper mine. These parameters are: rock quality designation (RQD), longest piece of intact rock and % of +1 inch. The RQD and the longest piece are actually measured on drill hole cores whereas % of +1 inch is visually estimated on the same cores. These size distribution curves are then utilized in a variety of engineering applications such as; slope instability analysis, blast design, copper recovery prediction from heap leaching, etc. The three rock fracture parameters for two dominant rock types (porphyry and schist) in the pit had to be estimated separately due to different rock fracture characteristics.' Both ordinary kriging (OK) with measured hard data only and soft kriging (SFTK) with hard and soft data were used to estimate each parameter. The cross validation of 100 measured sample values served as the-basis for evaluating the potential benefits of SFTK over OK. Use of subjective information during SFTK required obtaining (prior) probability distributions for all three rock fracture parameters. These distributions were obtained from the typical rock fracture parameters observed in drill hole cores falling inside the geologically interpreted structural domains with varying degrees. of fracture intensity and also through direct mapping along the exposed bench faces. Two different types of soft information were developed for this study; namely, Type "A" and Type "K". The former is based on sample distribution of fracture parameters whereas the latter is based on two step estimation designed to narrow the range of variation observed in data Type "A". The results of the cross validation were analyzed using a linear regression of actual values versus estimated values. The results confirm an improvement on the estimates made by SFTK with hard and. both types of soft data over those produced by OK with hard data only.

Jan 1, 1989

By Sandeep Kumar Jeripotula, Govinda Raj Mandela, Aruna Manglapady

Dumper operators are frequently exposed to whole body vibration (WBV) in surface mines. Surface mining activities involve the amalgamation of comparatively high intensity of vibration and extended exposure durations. Efficient risk reduction mandates knowing of important phases of a task that poses a threat to health of dumper operators. So far in India very limited studies have been reported on WBV exposure with regard to surface mines. This paper evaluates WBV of dumper operators based on ISO 2631-1:1997 Standards and European Union (EU) Directive 2002 for different phases of job cycle. Six dumpers were considered for this study and the vibration measurements were made for all the four phases of the job cycle by placing the triaxial accelerometer on the operator’s seat-surface and at the seat-back, independently. The findings of the study revealed that the haulage task (loaded travel and empty travel) remains the chief contributor to vibration exposure according to seat-surface and seat-back measurements. Maximum frequency weighted root mean square (RMS) of 1.12 m/s2 and 1.09 m/s2 were reported for empty travel task for seat-surface and seat-back measurements, respectively. For seat-surface measurements based on RMS, Z axis remains as the dominant axis of vibration for all the dumpers during haulage task, whereas for seat-back measurements, the dominant axis varies between X and Y. Exposure action value (EAV) based on RMS has exceeded the threshold value of 0.5 m/s2 for all the dumpers during loaded travel and empty travel for seat-surface as well as for seat-back measurements.

By W. Choi

The present study revealed that the bioleachability of a chalcopyrite flotation concentrate is influenced by the semiconductor properties of CuFeS2. The overall reaction of biooxidation,

Jan 1, 1991

By T. R. Ellis

Considerable movement is afoot internationally to rationalize standards and regulations relating to valuations and the qualifications for valuation professionals. In July 2000 the International Valuation Standards Committee released expanded standards, and additional important improvements are planned by 2003. Possible updates to the International Accounting Standards (IAS) and potential adoption of IAS by the U.S. could significantly impact minerals appraisers. Standards designed specifically for mineral asset valuation are under development in Canada and the U.S., with Australia’s internationally respected VALMIN Code providing the benchmark. In the U.S., the all-encompassing Uniform Standards of Professional Appraisal Practice (USPAP) is annually modified and continues to gain deeper acceptance, while the SEC holds fast to its antiquated rule prohibiting reporting of a quantitative estimate and value for non-reserve mineralization. Some important international trade agreements are driving actions to free the trade in professional services. In July 2000, an international workshop was held to initiate discussion on minimum qualifications for appraisers to work internationally. Pressure for uniform minimum qualifications and rules for professionals internationally will continue to build. The U.S. is historically among the slowest countries to implement such initiatives, with its state level licensure barriers having the potential to cause some of its professionals to be stranded in an international backwater. Structural change is needed in Australia’s VALMIN Code to remove conflict with the latest International Valuation Standards. The mineral valuation standards developers of Australia, Canada and the U.S. should work jointly on updating VALMIN for global use.

Jan 1, 2001

By B. J. Arnold

Prior laboratory work has demonstrated -that much of the fine ash-forming minerals entering a flotation froth are there as a result of water carry-over from the bulk contents of the flotation cell (Arnold and Aplan, 1986a). Using a bank of four 300 cu ft WEMCO flotation cells cleaning a well-liberated Lower Kittanning seam coal, test results show that the sulfur and ash content of the froth is directly related to the water content of the froth (or inversely related to the percent of solids in the froth). Reagent changes which result in a watery froth produce a higher ash content in the froth. A direct comparison of laboratory and plant results show that the standard laboratory flotation test produces a product higher in sulfur and ash than that produced in the plant. Caution should be exercised when extrapolating laboratory test results to the plant situation. A method of estimating coal flotation product quality in the plant based on laboratory tests is given.

Jan 1, 1990

By R. K. Mehta, C. W. Schultz, J. B. Bates

Introduction The Mineral Resources Institute, The University of Alabama, has for the past three years been engaged in a program to develop a beneficiation system for eastern (Devonian) oil shales. One objective of that program was to evaluate advanced technologies for effecting a kerogen-mineral matter separation. Column flotation was among the advanced technologies selected for evaluation. Early in the program it was shown that column flotation was superior to conventional (mechanical) flotation and to the other advanced technologies being evaluated. The investigation then proceeded toward the further objective of defining the optimum operating conditions for column flotation. One observation made in the course of optimization testing was that introducing the feed into the froth (above the pulp-froth interface) resulted in an improved combination of concentrate grade and kerogen recovery. This observation was reported in a previous paper (Schultz and Bates, 1989). Because the practice of maintaining the pulp froth interface below the feed point is contrary to "conventional" practice, it was decided to subject the observation to a systematic series of tests. This paper describes a recent series of tests and the results that were obtained. Experimental equipment and procedure The arrangement of the column cell and auxiliary equipment for continuous flow testing is shown schematically in Fig. 1. The feed sump [O] is filled with a sufficient volume of prepared sample to permit a large number of tests to be performed (typically 12). Past experience has shown this is necessary to control sample variability and variability in the size distribution resulting from ultra fine grinding. The feed slurry is maintained at about 20% solids and is constantly recirculated and stirred. The sample is metered from the circulating pipe by a peristaltic pump [O]. The feed slurry is diluted with reagentized water [O] by a second peristaltic pump [O]. Wash water [O], also reagentized, is supplied through a third peristaltic pump [O]. While this feed system may seem unduly complex, it does permit users to independently vary either the wash water rate or the net solids content of the cell. In the tests reported here, the feed rate and net percent solids were constant at 12.5 gms/min. and 3.3%, respectively. Diluted feed enters the column through 6.35 mm-diam (0.25 in.-diam) copper tubing and is discharged upwardly at the center of the column. Tailings are discharged through flexible tubing that can be adjusted so as to control the position of the pulp-froth interface. The column is 76.2 mm-internal-diam (3 in.-internal-diam) and 1090 mm (43 in.) high. It is made from lucite tubing and is fitted with a 51-mm-diam (2-in.-diam) fritted glass air sparger having an average pore diameter of 50 µm. In performing a series of tests, the concentrate and tailing are allowed to discharge continuously. The system is allowed to equilibrate for 30 minutes after the pulp and froth reach operating levels. Concentrate and tailing samples are taken simultaneously for timed intervals (five to 15 minutes, depending on the volume of sample desired). After sampling, a change in operating conditions is made and the system is again allowed to equilibrate. The tests to determine the effect of the pulp-froth interface level were part of a larger series of tests in which the objective was to optimize the conditions for a rougher flotation stage in a two stage circuit. The sample used in this series of tests was an Alabama shale ground to d90 = 23.1 µm and d50 = 7.9 µm. The operating conditions remaining constant in this series of tests were as follows: Column height - 1600 mm (63 in.) Air sparser - 50 µm (average pore diameter) Spray water - 130 cc/min. Feed rate - 12.5 gm/min (0.4 oz per min) (dry solids) Percent solids - 3.3% Frother (Dowfroth 250) - 45 ppm The variable test conditions are tabulated in Table 1. Positions of the pulp level (pulp froth interface) and feed entry are presented as a percentage of column height (as measured from the face of the air sparser). These test conditions are presented Fig. 2. At each of these test conditions, individual tests were performed at varying air

Jan 1, 1992

By W. A. Yuill

A process has been developed for increasing the grade of chalcopyrite concentrates from about 25 percent copper to about 60 percent copper. The concentrates are treated with two steps of autoclaving and then by flotation. Because of the lower associated weight, copper in the concentrates could be shipped and smelted at less cost than untreated concentrates. Use of the process can also increase overall yield from an orebody if a lower grade concentrate is sent to enrichment than would be sent to a smelter. Potential applications of the process would be for treating concentrates that must be transported a long distance for smelting or for treating concentrates so as to increase the capacity of a smelter.

Jan 1, 1984

By Isa Nozari, Asghar Azizi

The extraction of copper from sulfate leaching liquor was investigated using Acorga M5640 commercial extractant in kerosene diluent. The effects of important factors such as the extractant concentration, contact time, liquor pH, and temperature were examined on the separation factor Cu/Fe and the extraction efficiency of copper. The results indicated that nearly 92.32% copper was extracted from the leach liquor at 10% (v/v) Acorga M5640 concentration, 1:1 aqueous/organic phase ratio, 20 min contact time, pH 2.5, and 25 °C temperature. Also, the further increase in the values determined had no positive impact on the extraction of copper. Under these conditions, the separation factor Cu/Fe was obtained about 29.64. The extraction mechanism was studied applying the plot of log(D) – 2 pH against log [extractant] and it proved the association of two moles of Acorga M5640 for the extraction of one mole of copper. McCabe–Thiele diagram was constructed and a single-step extraction process was found to obtain themaximumextraction. Additionally, thermodynamic datawere investigated and the extraction process was endothermic and non-spontaneous at 298 K (ΔH = 27.05 and ΔG = 15.52 kJ mol−1). Moreover, the loaded organic phase was stripped and 80.94% copper was recovered after 20 min using 10% sulfuric acid concentration.

Jul 31, 2020

By Gabriel de Almeida

INTRODUCTION The widespread use of desktop computers by an ever increasing number of people, both for personal and for business and government uses, has brought public attention to surprising stories about computer abuse. Before the advent of microcomputers in the information processing environment, hundreds of amazing misdeeds involving large computers had already been reported, most of them perpetrated by highly skilled professionals. The undreamed enlarging of microcomputer potential has steadily posed a major threat to complex mainframe computing systems, as joyful teenagers become familiar with the habit of hacking around someone else's large processing system, by means of makeshift phone communication networks, based on their intended homework for personal computers -- for the sheer fun of it. Now, the never ending capacity and speed improvement of commercially available micros has given rise to a brand new concern for society: the hazards of processing sensitive information in the powerful, but still unsafe microcomputer itself, whether or not linked to other micros or mainframe networks. This paper deals with some aspects of the problems and presents some practical hints as to enhance protection and minimize risks to sensitive and secretive information when processed on microcomputers. The physical considerations of computer security and pertinent safety precautions will not be discussed, because while essentially relevant to information protection, recommendations are well defined by processing resources suppliers and their importance is more widely recognized by users in general. Definitions and Classifications. The following definitions and classifications will be considered in this report: Information Assets: Any knowledge or information processing, storing or conveying device displayed in one's environment. It consists of two main categories: INFORMATION RESOURCES: End user's application data wherever recorded. PROCESSING RESOURCES: EDP skilled user's hardware, software, peripherals, magnetic media, communication devices, auxiliary equipment, supplies and related operational procedures. Information Protection: In a broad sense this is the set of necessary procedures to assure to the legitimate user the effective control of the operation and allow modifications of information assets, so that their physical or cognitive integrity be preserved or any unexpected loss minimized inspite of accidental occurrences or intentional actions. Classification Processes: Commonly two classification processes are used to define key terms in information protection: SENSITIVE CLASSIFICATION: Pre-defined standards for assessing the vulnerability to losses due to lack of proper processing continuity if information is destroyed, disclosed, secluded, or misused. SECRECY CLASSIFICATION: A spectrum of degrees as to the expectancy of holding exclusiveness of unique information whose destruction, disclosure, seclusion or misuse will cause a negative impact on the legitimate holder environment. Sensitive Information: Any knowledge whose destruction. disclosure. seclusion or misuse - - - implies losses to its legitimate holder. It may be classified as: VITAL INFORMATION: An essential knowledge whose lack of proper availability implies total loss or termination of p

Jan 1, 1987

By J. DeYoung

Weak demand for metals and consequent low metal prices resulted in continuation of the depressed state of US mineral exploration activity through 1983. Data collected by Resources for the Future Inc. and The Pennsylvania State University for a cooperative study on mineral exploration activity indicate that US exploration in 1983 fell by as much as 25% from 1982 levels. Precious metals remained the focus of most exploration efforts, as gold and silver prices remained attractive compared to base metals. Reports of 1983 domestic exploration and development activities in several industry journals indicates that about 85% to 90% of those projects were directed primarily at gold and silver. Gold exploration included work by several companies on Carlin- type disseminated gold deposits in Nevada, geological prospecting and drilling in the Wenatchee Gold Belt in Washington, and interest in lode and placer gold properties in California, especially by several small Canadian firms. Precious metals exploration projects were also reported in Alaska, Arizona, Colorado, Montana, New Mexico, Oregon, South Dakota, and Utah. There was also tome precious metal exploration activity in the eastern US. Development continued at the Ropes gold mine near Ishpeming, MI, and companies explored historic gold-producing areas in the Southeast. Some exploration for nonprecious metals took place last year. Stratabound copper-silver deposits were examined in western Montana, and US Borax continued exploring molybdenum resources in the Misty Fjords area in Alaska. Work on these projects during 1983 may have been stimulated by time limits on the availability of certain federal lands for exploration more than by projected improvements in metal markets. During 1983, several papers were published on mineral exploration strategies and the future of US exploration. David Watson of Raymond Kaiser Engineers, in a paper presented at the 1983 AMC Mining Convention, forecast increased exploration activity for gold and silver because of world economic conditions. He added that antimony, manganese, chromium, graphite, mercury, tantalum, tin, and barite are also likely targets based on their limited domestic reserve availability. He cited concern over reported subsidized mineral production by foreign producers and US regulatory and land-planning policies as retarding mineral exploration activity. Douglas Cook of Freeport Exploration Co., at the same meeting, presented a paper that showed that a 1950-75 period of vigorous exploration has been followed by a period where acquisition has replaced exploration as the predominant means of acquiring new mineral properties. At a December IIASA conference on "The Economics of Mineral Exploration," in Vienna, Austria, A. Rose and R. Eggert of The Pennsylvania State University pointed out that recent exploration decisions tend to rely more on evaluating production costs and comparing them with existing deposits, rather than on return of

Jan 5, 1984

By J. S. Wozek

In metallurgical applications, coal fulfills dual roles as a chemical feed stock and as a fuel source. These applications range from cokemaking, ironrnaking (including pulverized coal injection), foundry, basic oxygen furnace / electric arc furnace coal additions, direct ironrnaking, Corex, and the futuristic direct steelmaking. In all steelmaking related processes, chemical reactions are simultaneously temperature and chemical dependent. Therefore, coals used in these processes must consistently comply with specific quality parameters in order to promote efficient operations. This paper limits discussion of Metallurgical Coal Quality to cokemaking and ironmaking applications. Its purpose is to present the customer's perspective on the control of critical coal and coke properties.

Jan 1, 1994

By N. J. Ferguson

An upsurge in demand for Australian coal has seen a much needed programme for a new generation of coal ports. This paper discusses design concepts in planning a large modern terminal, with the 25 Nt/a Port Kembla and the 50 Mt/a Newcastle facilities as practical examples. The need is emphasised for a studied Master Plan, in-built materials handling flexibility and staged development. Trends in bulk ship design and loading methods are noted. Features of these Australian designs include methods of dealing with poor ground conditions, functional civil engineering for environmental protection and optimal marine structure designs.

Jan 1, 1982

By Karl E. Elers

The term "potash" denotes a family of minerals and compounds of potassium, containing greatly varying percentages of that element. In commercial usage, most of the potash products are used in agriculture, where they are used to furnish potassium, one of the three basic elements for plant growth; the other two being nitrogen and phosphorus. Potassium's contribution to plant life is principally as a stalk strengthener, and if soils can no longer supply this basic element, then crop failure is inevitable without nutrition supplied from fertilization. While agriculture uses some 95 per cent of the potash produced, other industries require highly refined potash, for the manufacture of soaps, dyes, pharmaceuticals, synthetic rubber, insecticides, photographic film, and other products. Until the mid-nineteenth century, world agriculture had three options related to the potash content of soils: 1) crop rotation and pasturing to attempt to minimize the loss of potash in harvesting, 2) abandoning depleted and exhausted soils (part of the reason for the vast migration of populations in Europe and Asia), and 3) burning forests for the use of the ashes, and concentrating the nutritional value by boiling the ashes in large kettles, for "pot - ash". With the discovery in the mid 1800's and exploitation of potash from underground deposits in Germany, the beginning of the modern potash industry was established, but American potash requirements remained substantially dependent on German production until the 1920's, when oil drilling in the Permian Basin of New Mexico

Jan 1, 1972

By Larry D. Patts

Section 317(e) of the Federal Coal Mine Health & Safety Act of 1969 directed the Secretary of the Interior to prepare standards under which all working places in a mine shall be illuminated by permissible' lighting while persons are working in such places. Section 317(e) further provides that such Working places shall be illuminated within 18 months after such standards are promulgated. In accordance with this section of the Act, there was published in the Federal Register for December 31,1970 a notice of proposed ru1emaking which prescribed the illumination to be provided in the working p1 aces of underground coal mines. In 1ight of written comments, suggestions, and objections to this proposed ru1emaking, the proposed standards were with-drawn and reproposed in the Federal Register for Wednesday, October 27, 1971. In light of further comments, suggestions, and objections, a public hearing was held on April 4, 1974 and standards were again reproposed and published in the Federal Register for April 1, 1976. Promulgation of the final lighting standards took place on October 1, 1976 which means that the underground coal mining industry must comply with face illumination requirements by April 1, 1978. As mentioned previously, the first proposed ru1emaking for illumination of underground coal mines was published in the Federal Register on October 27, 1971. In early 1972, Consolidation Coal Company (Consol) and the United States Bureau of Mines agreed to a cooperative study of underground face illumination; Conso1 felt that expertise in this field would become increasingly important. Conso1's initial efforts in illumination were aimed at investigati.ng practical lighting systems for underground face equipment. We were concerned with installing unobtrusive lights which provided sufficient face illumination for safety, but at the same time were readily maintainable, electrically reliable, and physically sheltered from damage.

Jan 1, 1977

By B. K. Cantrell

The U.S. Bureau of Mines and others have conducted a number of occupational exposure surveys since the publication of the International Agency for Research on Cancer report of 1989, which labeled diesel exhaust as a probable human carcinogen. These surveys have assessed diesel exhaust exposure using measurement of diesel aerosol and/or specific polycyclic aromatic hydrocarbons as indicators of exposure. This paper reviews present diesel emission standards, available diesel exhaust aerosol measurement techniques, and the results of the occupational exposure surveys. In the surveys, diesel aerosol was emphasized because it is a major component of diesel exhaust, is suspected to contribute to the health hazard, and is readily measurable. Three primary aerosol measurement techniques were used: respirable combustible dust, size-selective sampling, and measurement of the elemental carbon fraction. Occupations surveyed included mine workers, railroad workers, forklift operators, fire fighters and truck drivers. The studies found mean diesel aerosol concentration levels in the range of 0.004 to 1.74 mg/m3? Highest aerosol exposures were in confined spaces such as mines where heavy diesel equipment is used. Polycyclic aromatic hydrocarbons typically are found at very low concentration levels and are not unique to diesel exhaust.

Jan 1, 1996

By M. E. Grimes

The Port Radium mine of Eldorado Mining and Refining Limited, located on Great Bear Lake only a few miles from the Arctic Circle in north-western Canada, is the oldest uranium producer in Canada, The first concentrates were produced in 1933 and except for a period between 1940 and 1942 the mill has operated continuously. Although it is located in a remote area, and compared to more recent mines in other areas is a small tonnage operation, nonetheless the relatively high grade of the Port Radium ore has permitted operation to date on an economical basis. The mill process at Port Radium includes the original gravity concentration mill, and since 1952 an acid leaching plant which treats tailings from the gravity mill and tailings recovered by dredging of residues from underwater dumps in Great Bear Lake. The pregnant solution from the leach plant has to date been processed through aluminum reduction to yield an intermediate grade uranous phosphate-arsenate precipitate, Because of the rising costs of the aluminum reduction process, and its sensitivity to ore composition, Eldorado became interested in possible application to Port Radium of the solvent extraction processes of which we were obtaining increasing information in the latter part of 1954 and during 1955.

Jan 1, 1958

By John MacDonald

An unstable economy has shown businesses what the mining industry has known for decades ? a successful business location today may not succeed in the future. Unexpected expenses, natural events and workforce changes have a big impact on the costs of production. To help focus production and maintenance budgets, mining executives are increasingly turning to production metrics to make key decisions. Role of mine and mill data Companies employ a variety of information systems to allow employees to accomplish their operational tasks, and each worker is focused on the metrics, or key performance indicators (KPI), for his or her individual function. For example, machine operators monitor throughput and cycle time to keep the machines running continuously and to meet daily production quotas. Meanwhile, the maintenance teams monitor machine performance, overall equipment effectiveness (OEE) and meantime between failure to predict and help prevent downtime.

Jan 1, 2013