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By K. Nielsen

The paper uses three examples to illustrate the challenges that the minerals industry is facing with regard to our image and the public?s perception of us. The paper then discusses communication with stakeholders as opposed to lecturing to the public and the authorities, and states that the industry needs to work more directly towards politicians and regulators as target groups. The conclusion is that we still have a way to go before the industry is doing enough to bring our message to the right people, but we are improving.

Jan 1, 2007

By Dolf Vos

The balling section of the pelletizing plant at Hoogovens IJmuiden consists of 7 balling drums. Each with an average capacity of 100 tons of green pellets per hour. The balling drums are equipped with rotating scrapers and water-spraying systems. The scrapers are installed in order to restrict the growth of the race to a certain thickness. The spraying system is used to adjust the desired value of the moisture-content of the rewetted ground ore, the pellets and the race. The desired value is the value by which the balling- process is stable, good pellets are formed and surge occurs within certain limits. In October 1980 the construction of one of the balling drums has been modified. The rotating scraper was removed and the inner wall of the drum was supplied with a rubber-lining. In 1982 a second balling drum has been rubber- lined. At the same time the Tyler vibrating screen of this balling circuit has been replaced by a roller(bed)screen. By the end of 1983 all 7 balling circuits will be equipped with rubber-lined drums in combination with roller(bed)screens. The combination of these two modifications will improve the quality and the screen analysis of the green pellets, moreover resulting in savings on energy- and maintenance costs. This paper describes the influence of a rubber- lining on the balling process and the green pellet quality by carrying out in-plant testruns in November/December 1980. The testrun results have been compared with the results of a not modified balling drum.

Jan 1, 1983

By James N. Prudden

Measurable physical characteristics of placer deposits include geological, geomorphological, sedimentological and mineralogical features which produce the complimentary ingredients with which one can formulate an economic evaluation of these complicated deposits within the confines of a well established geological model. Heavy mineral suite composition and character will change downstream from the provenance area and will compliment the related depositional environment. Careful attention to gold particle characterization during the exploration phase can indicate new source additions, enhance deposit evaluation methods and greatly assist in maximizing metallurgical efficiencies. Failure to recognize and measure these important features very frequently leads to frustrated and unrewarding placer evaluation goals. Increased general acceptance of sedimentology in the gological appraisal of ore bodies has progressed into the science of clastic sedimentalogy using measurable parameters to evaluate minable units. This branch of geology has developed as a tool in locating, defining, and mining alluvial concentrations of valuable heavy minerals. The repeatedly successful application of this valuable tool in conjunction with other classical geological methods can be directly related to the development of a geological model which formulates the distribution of detrital gold. This use of multiple geological techniques permits the transfer of routinely derived data to management. Standardized nomenclature permits the transmission of uniform information thereby promoting credible property evaluation. This approach enables organizations to critically assess large numbers of potential mining targets for definitive feasibility studies. Sedimentology must play an integral role in the evaluation of any alluvial deposit. The sampling problems associated with particulate gold are well known and frequently cause perplexing evaluation problems. Consequently, properly directed and executed

Jan 1, 1987

By Michael Taylor, Thomas W. BoBo

Currently two of the most important characteristics of construction aggregates are (a) the particle size distribution (psd) and (b) the “shape” of the aggregate particles. The long established test methods and standards for these properties require substantial resources and most suppliers can take samples and conduct tests at intervals measured in days (psd) or even months (shape). Furthermore these tests require time: so the results are available only after material has been stockpiled or shipped. In the rare cases where problems are found the out-of-spec material has often been shipped to points unknown. There are substantial advantages to be obtained if the psd and other geometrical properties could be obtained from the material as it moves through the production processes and if the results could be reported back within seconds or minutes to Plant Control Managers. This paper describes a single on-line system used to evaluate production of crushed material in a production quarry. The system consists of an enclosure (containing the camera and lighting etc.) mounted over a production belt. Images are fed by fiber optic cable to a nearby control room where the data are analyzed; stored; displayed; and made available for integration into a process control system. Numerous forms of display can be created according to the needs of the producer. Once programmed by an automation engineer all functions of operation are fully automated. The system has permitted over 400 tests per hour with a feed back time less than 2 seconds. Sufficient geometrical measurements are made so that many different “shape” factors can be computed on a similar time scale. The paper summarizes the results from approximately 100 shifts of about 8 hours each and compares the imaging method with the current standard hand methods. Study of the data generated showed that, when combined with additional plant information, the system can be used to generate additional useful control information.

Jan 1, 2005

Column flotation has been successfully implemented on a production scale in the Athabasca oil sands. In this application, bitumen is recovered and mineral matter is simultaneously rejected from a middling stream originating from a primary separation vessel. Exploiting the natural hydrophobicity of bitumen, the middlings streams have traditionally been processed utilizing conventional, mechanical flotation cells. Although these cells offer adequate bitumen recovery and mineral rejection rates, operating costs are high due to the required maintenance of the wetted mechanical components. In comparison, column flotation provides superior metallurgical performance while offering a lower maintenance demand. Both metallurgical and mechanical characteristics of column flotation are discussed to demonstrate the benefits of this technology for the recovery of bitumen from oil sands.

Jan 1, 2012

By Clement K. Chase, J. A. Eisele, Paul D. Chamberlain, Terry Laverty, Lee Rice, Larry Sevenker, Albert G. Law, Daryl Tweeton, John Peters

"Name your poison," wrote Forbes, Jan. 3, 1983, in an article describing the plight of much of the mineral industry as it entered the new year. "To ask which (mining) segment is better these days is almost like asking which of several stones would make a better life preserver." "The scene has seldom seemed darker or apparently less promising," said the Mining Journal in June 1982. And the Northern Miner described the year as the third in a "3-year drought which has completely dried up (company) coffers." Thus, 1982 became the worst year for much of the mining industry since the Great Depression. Low prices, commodity surpluses, output reductions, layoffs, temporary and permanent closures, and financial losses made headlines as the general recession continued to hurl blows at an industry facing strong foreign competition, increased government regulations, and plummeting market demand. At fault were tight US monetary policies and the resulting high interest rates that, while forcing inflation to slow, also threw the economic wheels of the country into reverse gear. Automobile production, housing starts, consumer durable sales, and capital spending all fell dramatically. US industrial production fell about 8.5% in 1982, with the GNP dropping by 1.7%. Production Value Not a single mineral escaped this recession. According to the US Bureau of Mines, US nonfuel production value dropped for all but four out of 21 metals and 14 out of 44 nonmetals. Production quantities increased for only gold, lead, and zirconium among metals and for only six nonmetals. Total nonfuel mineral production value dropped a whopping 21% from 1981 levels, the largest decline since 1938 and the first since 1971. Production value was estimated at $20 billion. Metal commodities showed heavier losses than nonmetals-37% vs. 12%-because of their link to depressed automobile and construction industries. Prices From peaks in early 1980, prices of precious and base metals, ferrous and nonferrous metals, and virtually every mineral dropped to 30-month lows in June 1982. Gold dropped to $9.64/g ($300/oz) compared to a high of $27/g ($850/ oz). Silver was quoted below 164/g ($5/oz) versus a $1.61/g ($50/oz) high. Copper was offered at a five-year low of $1.22/kg (55.5¢/lb) compared with a high of $3.30/kg ($1.50/lb). Lead went for 53¢/kg (24¢/lb) versus $1.21 (554). Nickel begged for buyers at $4.19/kg ($1.90/lb) compared to a high price of $7.72/kg ($3.50/lb). Molybdenum was available at or below $8.82/kg ($4/lb), down from a high of $44/kg ($20/lb). Cobalt went for $11/kg ($5/lb) versus $55/kg ($25/lb). Adjusted for inflation, increased currency costs, and currency devaluation, many of these prices are the lowest reached in decades. Financial Profits & Losses Low prices severely impacted companies' earnings, turning profits into sometimes disastrous or fatal losses. Robert Norton, director of the US Bureau of Mines, noting there has been a recession in the mineral industry for years, said, "Profit rates as related to invested capital have been considerably lower (for mining) than those of other industries. Mineral industry profits have been subject to greater cyclical swings and debt equity ratios have been significantly greater than

Jan 5, 1983

By Kenny Lo

"SummaryFor more than a century, ground freezing has been a construction technique used in stabilization of ground by means of lowering the temperature of surrounding soil strata. This technique is used in circumstances where conventional grouting method is unable to achieve the degree of consolidation required to prevent settlement and water ingress during the execution of underground excavation. Whilst ground freezing is effective in imparting self-supporting characteristics to the excavation profile, it poses significant challenges when it comes to the New Austrian Tunneling Method (NATM) where sprayed concrete is used to support the freshly excavated ground. Sprayed concrete, if used in an appropriate manner, provides a fast, efficient and structurally-reliable means of supporting the structure, especially in underground construction. The evolvement in sprayed concrete technology is attributed to the development of concrete know-how, improvement of spraying technique with the use of automation spraying equipment, more in-depth understanding of sprayed concrete behavior and enhancement of materials used in production of high quality sprayed concrete Not only has this markedly escalated the prominence of sprayed concrete on wider perspective,. the positive development has also pushed sprayed concrete beyond its boundaries, enabling it to be embarked on area of application not considered possible decades ago. Nevertheless, sprayed concrete, for all its placement versatility, still depends largely on the technicality provision very similar to concrete to achieve the required quality. Parameters such as raw material grading composition, curing temperature and cement quality are some of the factors that can easily sway the quality of concrete from one extreme to another. Conducive ambient temperature is critical in ensuring optimum hydration of concrete. This is more important in sprayed concrete where temperature plays a pivotal role in influencing the early strength and long term strength development. The low temperature imposed by ground freezing is everything but ideal for competent hydration to take place. This paper outlines how the innovative use of sprayed concrete helps to overcome the adverse ambient temperature in the construction of a 110m underground pedestrian walkway utilizing ground freezing technique in Hong Kong."

Jan 1, 2016

By Paul F. Ph. D. Ziemkiewicz, Courtney D. Black

According to the American Coal Ash Association, 105 million tons of coal combustion products (CCP) were produced by the power generating utilities in 1997. Of that total, 1.68 million tons were used in mining applications (ACAA, 1997). Results have ranged from the environmentally beneficial to neutral and, in some cases, detrimental. Twenty years ago coal ashes: bottom and fly ashes constituted nearly all CCPs. With the shift to new emission control technologies at power plants, however, large volumes of new products are being generated. Many do not lend themselves to traditional ash applications such as cement formulation. Many CCP disposal sites are not documented with reliable pre and post application monitoring. In this report we discuss types of CCP, their relevant characteristics and the mining environment. We have attempted to identify a range of documented applications and to draw conclusions about their environmental effects including benefits and adverse impacts.

Jan 1, 2000

By B. Valentim

Policies for reducing NOx emissions have led power plants to restrict O2, resulting in high-carbon fly ash production. Therefore, some potentially useful fly ash, such as the economizer fly ash, is discarded without a thorough knowledge of its composition. In order to characterize this type of fly ash, samples were collected from the economizer of a Portuguese power plant burning two low-sulfur bituminous coals. Characterization was also performed on economizer fly ash subsamples after wet sieving, density and magnetic separation. Analysis included atomic absorption spectroscopy, loss-on-ignition, scanning electron microscopy/energy-dispersive X-ray spectroscopy, optical microscopy, and micro-Raman spectroscopy. Key words: Fly ash; Petrology; Petrography; Economizer fly ash

Jan 1, 2009

By C. E. Jordan

The Bureau of Mines investigated a simultaneous elutriation and flotation technique for separating polyethylene terephthalate (PET) from polyvinylchloride (PVC). The Tuscaloosa Research Center, through a cooperative agreement with a recycling company, devised an elutriation-flotation method for beneficiating the mixed heavy plastics portion of municipal solid wastes which is composed of polystyrene (PS), PET, and PVC. A sodium carbonate brine was used to remove the lighter PS from the heavier PET and PVC. Over 98 pct of the PS was recovered in a high purity PS concentrate containing 99.7 pct PS, The remaining PET and PVC mixture was washed to remove the brine salts that would be harmful to the flotation process. The clean PET and PVC mixture was conditioned in a solution of 45 g/t gelatine and floated in a short (l-m) column flotation cell in an upward flow of water. In a single flotation step, over 75 pct of the PET was recovered in a high purity product containing 99.8 pct PET. The bubbles attached to the PET lowered the effective density of the PET-bubble agglomerate and allowed successful separation of these agglomerates from the PVC plastic pieces. This method separated two-thirds of the mixed plastics fraction into high purity PS and PET products suitable for recycling and left only one-third of the plastics in the mixed plastics product.

Jan 1, 1992

By Glenn P. Jones

Laterization of syenite and other rocks in north Alabama produced material which was picked up and carried by streams to southeast Alabama. These streams deposited the aluminum rich material in the sinkholes of a karst topography developed on the Clayton Limestone. Measurement of the bearing of the long axis of each deposit in the Screamer area, along with plotting the location of these deposits on a map, indicate a depositional pattern controlled by local fractures or solution zones in the Clayton Limestone. The sinkholes and channels dictated the original structure of the deposits. Additional structure changes have resulted since compaction of the deposits by continued solution of the underlying limestone. The original material in these deposits was enriched by the removal of silica to form bausite and bauxitic kaolin during deposition and compaction. Subsequent ground water action has reintroduced silica into the deposit leaving a core of bauxite.

Jan 1, 1972

By R. H. King

Suboleski and King (1990) analyzed the reasons for the dramatic increase in underground coal mine productivity during the last 10 years. This paper examines whether this increase can be extended. The paper forecasts whether the mix of technological, procedural and other factors that produced the increase will change in the future. The forecast is based on the base case and spreadsheet production model described in the previous paper.

Jan 1, 1991

By G. E. McClelland

In recent years exploration and development of low-grade sulfide precious metal ore deposits has increased. Low- grade ores are usually processed using conventional heap leach cyanidation methods. The potential for acid mine drainage from spent sulfide ore heap leached residues remains a concern even though the processed residue is stacked on an impervious liner system. It is therefore of critical importance to evaluate methods for long term prevention of acid mine drainage from sulfide heap leachable ores during the precious metal recovery process rather than mitigation during the closure and reclamation phase. This paper discusses two simple AMD prevention options for the recovery process phase. Laboratory evaluations were made using a modified humidity cell kinetic AMD test method on two low-grade sulfide ores without addition of an alkaline component and on the same ores with natural limestone or acid neutralizing oxide ore blended with the feeds before kinetic testing. Laboratory results are discussed in detail and demonstrate that blending an acid neutralizing component with sulfide ore effectively prevents the production of acid from the processed residue.

Jan 1, 1996

The solution mining review did not arrive in time for publication in the May issue. The term solution mining is commonly used to refer to heap leaching, dump leaching, in situ mining and bore hole slurry mining technologies. The US Bureau of Mines is continuing with research in these areas. Commercial application of these technologies is progressing. There is an ongoing cooperative research project between the Bureau of Mines and the Santa Cruz Joint Venture to evaluate in situ copper mining at a field site near Casa Grande, AZ. The project is currently in the environmental permitting stage. The Bureau is preparing an environmental assessment for the project as part of the National Environmental Policy Act. The Bureau is also continuing with laboratory experiments to study the leaching characteristics of atacamite ore from the field test site, as

Jan 1, 1993

By F. S. Knoll

Electrostatic separation is one of the most misunderstood physical processes used to beneficiate minerals. Nonetheless, millions of tons of titanium ores, iron ores and other minerals are processed every year economically, efficiently and safely. Over the past ten years major advances in electrostatic separation and its application have occurred. New processes include dewatering clay slurries, separating halite and sylvite, and shape separation of vermiculite and gangue minerals. Electrostatic separation techniques are based on one of two methods, electrophoresis or dieleccrophoresis -- processes involving charged and uncharged particles respectively. In some cases, the combination of these two techniques has proven quite useful. The purpose of this paper is to provide a basic understanding of the physical processes collectively called "electro- static separation" in order to enhance one's ability to define and consider new possibilities in mineral processing and other fields.

Jan 1, 1984

By C. H. Smith

The present interest in beryllium seems to be the result of recent developments in the uses for the metal discovery of significant deposits of disseminated beryllium ores, and the development of chemical and physical processing techniques, for recovering the beryllium values contained in these ores. At the present time most of the new and potential uses for beryllium are in the research stage of development and are not consuming large quantities of the metal. However, they do point to an expanding market. Interesting new discoveries or extensions of previously known deposits have been reported during the past year from the Boomer Mine in Colorado, the Mesquite area of Nevada,, the Chemalloy pegmatites in Canada, the Brazilian and African pegmatite districts and from other areas, However, this paper will discuss only four of the beryllium deposits, which appear to be of special significance due to their; large reserves of ore and promise economic development. The new chemical and physical processing techniques are not discussed in detail, but it should be stressed that the development of an economical process to handle the pegmatitic and low-grade non-pegmatitic beryllium ores is of great importance to the development of the beryllium industry. Scientists in both government and industry are co-operating in this effort and it is expected that commercial processes will be developed in the near future.

Jan 1, 1962

By Z. Hajnal

Three years ago a research program was initiated at the University of Saskatchewan to develop seismic surveying techniques for use in the Precambrian geological environment. The success of the reflection method in many younger geological settings suggested that this is the technique which would be the most suitable for experimentation. A successful adaptation of this technique to the Shield environment would make mapping of rock formations possible to much greater depth than is possible at the present time with any other applied geophysical technique. This presentation attempts to illustrate the advances which have been made in this program and will provide some insight into future plans. The field investigations were limited to the Flin Flon basin near to the town of Flin Flon, Manitoba (Fig. 1). This area was chosen because the surface geology has been mapped in great detail and it is a very important base metal producing region. It is an ancient sedimentary basin with some characteristics similar to areas where the reflection method has been successful.

Jan 1, 1976

By N. D. Jagger, I. M. Arbuthnot

Introduction Over the last five years, a large number of small- to medium-sized carbon-in-pulp treatment plants have been built in Australia, most designed to treat between 250,000 t/a and 1.5 Mt/a of ore. Because of the limited capital resources and tight cash-flow positions of these relatively small mining companies, the primary requirement was often to get a plant built and operating in a short period of time and at minimal capital cost. Therefore, since the inclusion of both pre-leach and tailings thickeners represents an obvious and significant capital cost, most of these plants were built without thickeners or even detailed, cost-benefit analyses on their inclusion. In some cases, the increasing use of High Rate Thickeners (HRTs) in the mineral processing industries has, however, resulted in a reassessment, because of their considerably lower cost. This reassessment was triggered primarily by the need to conserve water in arid mining areas where borefields are costly to install and water is limited. With the startup and operation of these installations, the resulting significant savings in cyanide consumption has been recognized, in many situations, as a primary justification for the installation of HRTs. Solution balances Degradation of cyanide occurs in the tailings water discharge to slime dams. The degree of degradation (cyanide loss) in the water recovered depends on a number of factors, but it is usually assumed to be about 90%. The most important mechanisms of CN loss are through HCN losses and oxidation by oxygen in the air, which also assists in the hydrolysis of CN. These mechanisms are supported by the large dam surface area and the long retention time of the tailings water in the dam. By thickening the CIP tailings at the plant and recovering as much tailings water as immediately possible, these losses are avoided. The retention time in an HRT is less than three hours, and the surface area is relatively small. Therefore, CN losses are negligible, which is not necessarily the case in conventionally-sized thickeners. Fig. I shows a block diagram of a 100-t/h gold plant without a thickener. In this example, 50% of the tailings water pumped to the tailings dam is recovered, and the CN concentration of the returned water is 10% of the tailings CN concentration of 150 ppm. Fig. 2 represents a plant with an HRT on tailings, thickening to 55% w/w solids. In this case, the thickened tailings are pumped to the dam, and 25% of the contained water is recovered. The recovered water and the mill make-up water are not sent directly to the mill; instead, they are added to the thickener feed and mixed with it prior to thickening. By doing this, the tailings are effectively washed, and the additional cyanide is recovered. Solution balances over these two circuits show cyanide recoveries of 5% and 65%, respectively. Thus, the thickener use increases cyanide recovery by 60%. Fig. 3 shows a two-stage HRT circuit in a countercurrent decantation (CCD) configuration. In this example, an additional 13% of cyanide is recovered through the use of the second-stage unit. This configuration can be justified when residual cyanide levels are high. Capital and operating costs - Case study 1 Illustrative cost figures are based on a CIP tailings thickener installed, in early 1988, as part of Dominion Mining's treatment plant at Paddy's Flat near Meekatharra. (All costs within this paper, unless stated otherwise, are in Australian dollars.) [Assumptions: Feed rate 150 t/h Ore moisture content 5% Leach density 40% solids Underflow density 55% solids Residual cyanide in tailings 150 g/m3 Flocculant dosage 15 g/t Consumable costs: Water $ 0.40/m3 Cyanide$ 2.00/kg Flocculant$ 4.50/kg Power$ 0.12/kWh Length of tailings pipeline2,500 m Capital costs of the major items involved in the thickener installation are given below: Thickener unit, 15-m diam $ 230,000 Water return pumps 12,000 Water recirculation pumps 28,000 Feed box 5,000 Flocculant make-up system 18,000 Flocculant storage tank and dosing pumps 11,000 Piping and valves 85,000 Electrics and instruments 47,000 Civil works 29,000 Installation 69,000 Total cost$ 534,000] Savings in capital costs that can be attributed to the

Jan 1, 1993

By A. J. Monhemius, R. G. Reddy, G. W. Warren, E. Peters

Thermodynamic solubility of chromium in pickling solutions (i.e., HF- HN03-H2O solutions) was determined as a function of HF and HNO3 acid concentrations at 298K. Pure Cr, AISI type 316 and 416 stainless steel were used in this study. The results showed that the solubility of Cr increased with increase in the concentrations of HF and HNO3 acids in solutions. The solubility of Cr increased in the order of pure Cr > 416 SS > 316 SS. The theoretically calculated Cr solubility data were in reasonable agreement with the experimental data.

Jan 1, 1993

By Clinton Strachan, Dirk J. A. van Zyl

11.1 INTRODUCTION This chapter outlines some of the selection and design considerations for leach pads and liners. Leach pads and liners are generally chosen to provide the required or desired levels of low permeability and foundation conditions at minimum cost. The selection and design of a particular liner depends upon its anticipated use and performance, and what materials may be available. A leach pad is the firm base for a heap. When geomembrane liners are used, the pad is the firm, compacted foundation upon which the liner is placed. In the case of a clay liner, the clay liner is usually also the pad. It is important to consider the design of a pad or liner in terms of a system. The "leach pad system" consists of the prepared foundation, bedding layer (if used), liner (s), seepage collection or detection layer (if used), and cover layer. Foundation preparation is necessary to ensure a stable base for the rest of the leach pad system. A bedding layer is used to protect a liner from being punctured by large angular fragments in the foundation material. A seepage collection or detection layer, consisting of well-drained material and (sometimes) pipes draining to a collection sump, is included when a double liner is used. A cover layer on top of the liner can serve the following purposes (van Zyl and Strachan, 1986): • Preventing of ultraviolet light exposure to sensitive geomembranes; • Limiting evaporation from compacted clay liners and thereby eliminating cracking of such liners; • More efficient collecting of leachate; and • Protecting the liner from damage during heap construction. Economic evaluations of alternative liners for a project must include the overall system. For example, a geomembrane liner may require different foundation preparation and cover material selection and placement than a clay liner. Liners can be made of compacted clay onsite, amended soil, or geomembranes. Geomembrane is a generic term that has been proposed to replace many terms, including synthetic membranes, polymeric membranes, plastic

Jan 1, 1988