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By Raj K. Singhal

Canada is a world class producer and exporter of minerals and mineral products. Canadian open-pit mines are highly mechanized and use state-of-the-art equipment and support technology. During the past few years, productivity improvements at Canadian open-pit mines have been achieved by taking advantage of larger equipment, in-pit crushing and conveying, truck dispatch systems and electronic management tools. The most recent developments are related to hydraulic transportation and the application of global positioning systems (GPS). Mine planning has become computerized. Environmental issues are dealt with in all phases of planning. Equipment modifications are pursued with vigor to keep the equipment functioning in the hostile Canadian north. In 1997, the mining and mineral processing sector employed 370,000 Canadians, contributing $26.2 billion to Canada's gross domestic product (GDP). The value of production of the Canadian mineral industry, including coal, amounted to $19.1 billion in 1997. Gold remained Canada's leading mineral with production valued at $2.8 billion. This was followed by copper ($2 billion), coal ($1.9 billion), zinc ($1.6 billion) and nickel ($1.9 billion). [ ] Synthetic crude oil from oil-sands mining operations in Alberta represents an important part of Canada's petroleum production. In 1997, the value of synthetic oil production was $2.87 billion. Canadian oil-sands mining has contributed significant technology developments in Canada.

Jan 1, 1999

The mining industry is an important economical factor in Vietnam. Mining is presently being conducted at about 60 locations and at over 1000 mines. Petroleum extraction and coal mining are the most important parts of industry though metals such as zinc, tin, chromites, iron are also extracted. Last year the sector produced 20 million tons of crude oil, 26 million tons of coal and 500,000 tons of apatite. In particular, Vietnam is one of the world?s largest producers of anthracite, and it is one of the top producers of ilmenite and zircon in the Asia-Pacific region. The government intends to increase the mining production on all levels, however, at present one can observe adverse impacts of the mining activities on the natural environment such as insufficient waste dump rehabilitation, occurrence of acid mine drainage, mining subsidence and emissions as well as lack of appropriate water treatment facilities. This paper describes the current mining situation, future perspectives, the major environmental challenges of the country and approaches to solve these problems. Particular emphasis will be given to the research project ?RAME ? Research Association on Mining and Environment in Vietnam?, a venture carried out by universities, research centres and industry. This project is worked out in collaboration with the national Vietnamese coal and industrial minerals company VINACOMIN.

Jan 1, 2006

By H. Walqui, S. K. Kawatra, C. H. N. Jeltema, T. C. Eisele

"The literature contains many cases where the shape of hydrocyclone efficiency curves vary from the ideal “S” shape. These often appear as changes in slope, or inflections. These inflections can be divided into two categories: “coarse” inflections, which are caused by differences in the density of the minerals being separated, and “fine” inflections, for which there are a number of competing hypotheses concerning their cause. The existing literature addresses either the fine inflection or the coarse inflection, but no studies have reported both types of inflection occurring at once in a single hydrocyclone test. This paper presents hydrocyclone results from both in-plant studies and laboratory experiments that show both coarse and fine inflections. The industrial significance of both types of inflections is discussed. Hydrocyclone efficiency curves show the probability of any given particle reporting to the hydrocyclone underflow as a function of its size. Selectivity functions, S(d), are used to represent the fraction of the feed material in size fraction “d” that reports to the hydrocyclone underflow. Plotting this selectivity function against particle size leads to the standard S-shaped efficiency curve shown in Fig. 1. In the “uncorrected” curve, the tail of the curve does not go through 0%, because a portion of the solids are bypassing classification. This happens as a result of their being carried along by the water, and is most important for the finest particles. The curve can be “corrected” based on the fraction of the feed water that reports to the underflow, represented by the bypass fraction, Rf. The corrected curve then normally passes through 0%, as shown in Fig. 1.The act of correcting the curve shifts the value of the d50 size, which is the size that has an equal probability of reporting to either the overflow or to the underflow. Correcting the curve to account for the bypass fraction makes it easier to compare cyclone performance under conditions that cause the quantity of water in the underflow to change, but that do not alter the actual corrected cut size (d50c).The corrected efficiency curve can be expressed closely by equations such as Plitt (1976):"

Jan 1, 2015

By B. J. Scheiner

The Bureau of Mines, Department of Interior, has been investigating the use of polyethylene oxide (PEO) as a flocculant for a variety of mineral wastes. As part of this investigation, the hydrodynamics of the flocculation process were studied. It was determined that to obtain optimum dewatering results, the factors of energy input into the stirrer, polymer concentration, and polymer dosage must be considered. Lt was found that at a given polymer concentration, there was an optimum stirrer speed and polymer dosage. With excess PEO, the amount of water removed in the trommel decreased, but no evidence for steric stabilization was observed.

Jan 1, 1987

By K. J. Shoop

Coal-fired power plants in the U. S. produce approximately 20 million metric tons of Hue-gas desulfurization sludge every year. The sludge mainly consists of calcium sulfite and calcium sulfate. This can be converted to synthetic gypsum, which in principle could be a marketable commodity. However, many Hue-gas scrubbers produce sludges that do not meet the quality requirements of the gypsum industry, and so their sludges must be landfilled as a waste. If a suitable method can be developed for removing certain objectionable impurities from the sludge, it will then be possible to market the material instead of landfilling it. A sludge from a natural-oxidation scrubber was characterized, and the main contaminant was found to be calcium carbonate from unreacted limestone. Based on the particle size and the characteristics of the material, froth flotation was considered as a method for purifying the material. Since no flotation studies have ever been carried out to separate calcium carbonate particles from calcium sulfite or calcium sulfate particles, it was first necessary to select a suitable collecting reagent. Based on Zeta-potential studies, the most suitable reagent was found to be an octadecylamine-octadecylguanidine complex. Results are presented for flotation of calcium carbonate from scrubber sludge using this reagent, in a reverse-flotation process. The best results were obtained when the sludge was first pre-cleaned using a water-only cyclone to remove unfloatable coarse limestone, followed by froth flotation to remove fine limestone.

Jan 1, 1998

By E. H. Cho

A current environmental concern is the cleanup and restoration of soil contaminated with low-level radionuclides at DOE sites including the Nevada Test Site. At the present, there is no applicable process to economically and effectively deal with the remediation of contaminated soils. This situation requires development of a selective flotation process to separate the radionuclides from contaminated soil efficiently and economically. In this study, a minus 200 mesh size fraction of pure cerium dioxide was used as a surrogate for plutonium oxide which is the major contaminant at the Nevada Test Site. A Hallimond flotation cell was utilized to examine the flotation behavior of cerium dioxide with oleic acid under various conditions of pH and collector concentration Mechanical cell tests were conducted to float the surrogate from a mixture with uncontaminated Nevada Test Site soil in the absence and presence of calcium carbonate as a carrier. Two different sizes of the carrier (minus 150 mesh and 65-150 mesh) were tested. It was found through the Hallimond cell flotation tests that the cerium dioxide could be floated well at pH's 4 and 9 with 10-3 molar oleic acid. It was also found that the addition of the carrier drastically enhanced the flotation recovery of cerium dioxide. The flotation recovery of the surrogate increased from 34 % to 65 % by adding only 0.5 % calcium carbonate (minus 150 mesh) in the feed and also increased to 95 % by adding 10 % of this carrier to the feed. The finer size fraction of calcium carbonate (minus 150 mesh) was more effective in recovering cerium dioxide than the coarser size fraction (65-150 mesh) The flotation method utilizing a carrier of calcium carbonate seems to provide a high potential to be used for the remediation of soil contaminated with radionuclides at various Department of Energy's nuclear weapon sites.

Jan 1, 1996

By Sahendra Ram, Ashok Kumar, Rakesh Kumar, AMIT KUMAR SINGH, Dheeraj Kumar, Arun Kumar Singh, Rajendra Singh

This article offers an examination of a retreat mining method conducted at the Pinoura Mine in India from 2010 to 2017. The method is atypical for coal mines of India’s coalfields. The method executes depillaring in a single pass and does not require the formation of galleries and support installation in splits, thus, reducing the cycle time. A variety of observations are discussed throughout this work and emphasis is placed on field measurements and depillaring under weak roof (RMR = 40–45). This paper discusses design techniques, specifically the estimation of the snook (remnant pillar) size, and important practical observations after the fact. The execution of this method was eventually conducted in eleven panels.

Aug 4, 2020

By R. Pazhianur

Cathodic Protection using impressed current was employed to reduce the wear of the mill wall during ball mill grinding. Wear rates were determined from weight-loss measurements made on four, I-inch diameter, mild steel coupons installed flush with the interior surface of the mill wall. Grinding tests were conducted on quartz, pyrite and quartz-pyrite mixtures at pH values of 4.6, 7.1 and 9.2. Cathodic protection was shown to reduce mill wear by 40-60010. An examination of the coupon surfaces using scanning electron microscopy showed that cathodic protection greatly reduced pitting corrosion. The presence of a sulfide mineral, such as pyrite, was found to increase the wear rate significantly, possibly due to galvanic interactions. It is also found that the wear rate is significantly higher than the sum of abrasive wear and the corrosive wear, due to a synergistic effect.

Jan 1, 1996

By V. Svalbonas, S. M. Jones, A. Boughey

In June 1998, the world's largest grinding mill, the 40 ft (12.2 m) diameter 20 MW Cadia gearless SAG mill, was commissioned. This was a leap of over40% above the largest operating SAG mill. A significant saving in capital cost gave the incentive necessary for a single mill line at Cadia, resulting in the selection of the 40 ft (12.2 m) diameter mill. Now, after 18 months of operation, this paper will review the significant items involved in the development, design, manufacture, installation, and operation of this mill.

Jan 1, 2000

By Jon Y. Kaneshiro, Eric Dawson, Pooyan Asadollahi, Steven Hunt

This paper provides updates to the paper published by the lead author at RETC 2011 with a summary of developments in technologies, products, and approaches to corrosion analyses of gravity sewer tunnels and microtunnels. This paper presents approaches in evaluating degradation of reinforced concrete liners. Also, the carbon footprint of conventional concrete liners and alternative “green” liners are compared and their life cycle costs are considered. A few case histories from the past decade are provided indicating the latest and emerging trends in liner protection.

Jun 13, 2023

By Peter McKenna

Different reefs being extracted from a mine will, in all likelihood, have significantly different semi-variogram models - and these will probably vary from geozone to geozone. As errors of estimation are dependent on the semi- variogram parameters, it follows, if a mine samples all reefs in all sections using the same sampling grid pattern, that estimation errors (or limits of confidence) will not be the same throughout the mine. This may be an undesirable situation! A geostatistical study of the relative merits of alternative sampling arrangements has been carried out by considering different reefs in different sections of a South African gold mine.

Jan 1, 1989

By K. Marutiram, T. Umadevi, R. Sah, K. Abhishek

Low-grade iron ore received from the West Singhbhum area of Jharkhand state in India was used to develop a beneficiation flow sheet to remove alumina (Al2O3) and silica (SiO2 ) from the ore to get iron (Fe)-rich product for steel plants. Mineral characterization showed that the main mineral constituents present in the head sample are goethite, limonite, hematite, quartz, clay and gibbsite. The head sample contained about 49.2 percent Fe, 8.79 percent alumina and 12.01 percent silica. The received iron ore sample is amenable to upgradation through beneficiation to get pellet grade concentrate. The beneficiation process was established, involving crushing, screening, jigging, spiral separation, size reduction, desliming and magnetic separation. The process showed significant enrichment in Fe values to 63.5 percent Fe in concentrate, from 49.2 percent Fe. From the developed flow sheet, it is possible to obtain pellet grade fines with 63.5 percent Fe, 2.92 percent SiO2 and 2.61 percent Al2O3 with 50.6 percent weight recovery. The overall tailing loss is 49.4 percent with 34.3 percent Fe, 21.28 percent SiO2 and 14.64 percent Al2O3

By William A. Cline

The iron mine and beneficiation facilities of Marcona Mining Company are located on the coast of south central Peru. The facilities include an open pit mine, crushing, concentrator containing grinding, magnetic-separation and flotation facilities, pelletizing plants and a completely self sufficient infrastructure. Total production capability is about 10,000,000 DLTPY, of which almost 6,000,000 DLT result from the fine-grind magnetic concentrate. Over 1,500,000 DLT of fine-grind concentrate is obtained from processing high-pyrrhotite ore. Although the orebody contains quantities of oxidized primary ore and transitional ores (mixed magnetite and hematite), the principal ore is predominantly a coarsely crystalline to fine grained massive magnetite.(l-3) In the primary ore the major impurities found are silicates and the iron sulfides- pyrite and pyrrhotite. Sulfur levels typically average about three percent although levels of five percent are not unusual and some ores contain up to ten percent total sulfides. In general the silicates and pyrite are readily rejected from finely ground primary ore by magnetic separation and very basic froth flotation processes. The high iron, low sulfur concentrate produced is particularly suitable for production of high quality oxide pellets. However, pyrrhotite is not removed from the magnetite matrix by either of' these simple beneficiation methods.

Jan 1, 1974

By G. J. Gersbach

The Robe River Iron Ore Project began in 1962 when Cliffs International acquired mining leases in Western Australia's Pilbara Region. Initial reserves were proven and bulk ore samples sent to the U.S.A. for pilot plant testwork. Cliffs Western Australian Mining Company Pty. Limited (30%) manages the project in joint venture with Mitsui Iron Ore Development Pty. Limited (30%), Robe River Limited (35%) and Cape Lambert Iron Associates (5%).

Jan 1, 1983

By Hassan El-Shall

Treatment of plant effluent including waste water and associated soluble and insoluble substances, is of a primary concern of many process industries including mineral processing operations. The major objective of such treatment is the removal of such impurities which can interfere with the process through the use of recycled water, and/or to comply with environmental ordinances. For example, Ramirez and Clements (1978) state that molybdenum contents in the range of 19 mg/1 eventually poison ion exchange resigns used for the extraction of uranium. In addition, recent restrictions by the EPA on molybdenum discharge values for mining waste water necessitate removal of this metal to (0.5-1.0 mg/1).

Jan 1, 1984

By S. R. Titley

Carbonate-hosted massive sulfide (60%) ores of the western Cordillera compose a distinct class of deposits although they vary widely in detail and perhaps genesis. They have been important sources of lead, zinc, copper, silver, gold, and more rarely, molybdenum, tin, and tungsten in complex mineral assemblages usually dominated by pyrite. They occur as concordant stratiform bodies, as discordant mantos, and as chimneys crossing tens of meters of section; many are associated with faults and breccia bodies. Environments of formation of carbonate hosts range from craton basin to shelf with ages from Proterozoic to Cretaceous; in many instances, dating has shown mineralization to be significantly younger than hosts. Temperatures of formation determined for many deposits are high (200°-400°) and many districts are centers of igneous activity manifested by dikes, sills, and stocks. However, direct cause and effect relationships have been difficult to establish. Many important problems attend the renewed interest and study of these deposits and include questions of metal-sulfur sources, metallization processes and histories, geological controls at all scales, and relationships to broader patterns of metallogeny.

Jan 1, 1985

By T. P. Meloy

A methodology is presented for finding feasible or locally optimal designs in the class of homogeneous, countercurrent, processing networks performing two-component non-sharp separations. The advantage of the methodology developed here is that given a set of independent performance criteria (specifications such as network separation factor, beneficiation ratio or recovery), a feasible or locally optimal countercurrent network design meeting those criteria can be found in one step. In the methodology, graph-theory was used to explicitly obtain the exact network responses of specific countercurrent networks. These responses were used to formulate the linear recursion equations whose solution gives the expressions for the countercurrent network responses which are a function of the stage transfer functions for two-component, non-sharp separations. These expressions are also functions of the network variables n and c. These expressions, together with the set of independent design criteria, were solved simultaneously for n and c using the Levenberg-Marquardt algorithm for systems of constrained, non-linear equations. The network variables n and c embody the coded network design information which is used to find the feasible network design which satisfies the set of independent performance criteria.

Jan 1, 1994

By VIVEK KASHYAP, PATRICK TAYLOR

The presence of iron in sphalerite induces the formation of zinc ferrite (ZF) during roasting. Zinc refinery residues (ZRR) and electric arc furnace dust (EAFD) contain a significant amount of zinc ferrite and are difficult to treat. According to the literature, up to 71% ZF has been found to be present in ZRR. The dissolution of zinc ferrite is inefficient even in aqua regia. The Waelz process is an existing process to recover zinc from electric arc furnace dust by reduction using carbon monoxide followed by the volatilization of zinc. In this study, zinc was selectively extracted from zinc ferrite by partial reduction of zinc ferrite at relatively low temperature followed by leaching in dilute sulfuric acid (20 g/L). Pure zinc ferrite samples were partially reduced to zinc oxide and magnetite by using H2 gas as a reductant. The presence of magnetite and zinc oxide was confirmed by X-ray diffraction (XRD) technique. A maximum of 95%zinc extraction was achieved after leaching with sulfuric acid on the reacted samples. The paper also discusses the effect of time, temperature, and concentration of H2 in the reducing gas on the extraction of zinc and iron from ZF.

Sep 16, 2020

By Marcelo de Oliveira, Antoine Allanore, Dennis P. Chen, Davide Ciceri

Potassium fertilizers (potash) are mined in a handful of countries in the Northern Hemisphere. Potash is either expensive or unavailable to the farmers of the Southern Hemisphere. Alkaline alteration of K-feldspar rock (ultrapotassic syenite) in autoclave in the presence of Ca2+ generates a mixture of K-bearing calcium-aluminum-silicate-hydrate (C-A-S-H) minerals that potentially can be used as an alternative local fertilizer. This work investigates the effect of processing temperature (200 °C, 220 °C, and 230 °C) and time (from 0.5 to 3.0 h) on pH, mineralogy, and elemental availability of the C-A-S-H mineral mixture. Increasing temperature results in an increased conversion of K-feldspar and increased content of both the mineral tobermorite (Ca5Si6O16(OH)2·4H2O) and amorphous phase in the resulting C-A-S-H mixture; increasing time results in an increased conversion of α-dicalcium silicate hydrate into tobermorite. The amount of K leached from the mixture is relatively constant across all processing conditions. Hydrothermal alteration in autoclave of K-feldspar-bearing rocks such as ultrapotassic syenite permits the synthesis of a potential potassium fertilizer which alkalinity and mineralogy can be tailored according to soil requirements.

May 22, 2020

By Alper Kirmaci, Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

Injuries and fatalities resulting from roof falls are still a major concern in U.S. coal mines, and many researchers are focused on developing meaningful approaches to minimize this hazard. In the United States, coal mine roofs can vary widely in composition, geometry, and inherent heterogeneity, leading to a wide array of different roof fall failure types. Researchers frequently employ numerical modeling tools to reproduce this physical phenomenon and provide key guides to engineers regarding roof conditions and control as long as the input data and constitutive relations are appropriately selected. Simulating such complexity requires expertise and constitutive models that adequately simulate roof behaviors. However, the currently available constitutive models have shortcomings in capturing some of the roof fall failure types common in underground coal mines, such as guttering. A new constitutive model is developed to address the shortcomings of constitutive models commonly used for coal roof stability analysis. The constitutive model developed in this study combines the anisotropic-elasticity and nonlinear strain-softening responses. In addition, the developed constitutive model can simulate up to three different joint sets implicitly, allowing for use in both continuum and discontinuum settings, and can be used in both Lagrangian finite-volume and distinct element method codes of Itasca. First, the mathematical expressions of the model are provided. Afterward, the validation phase of the developed model that covers comparisons with analytical solutions and those of existing models (e.g., anisotropic elasticity, ubiquitous-joint, and bilinear strain-hardening/softening ubiquitous-joint plasticity) is presented. Finally, a hypothetical coal mine roadway facing high horizontal stress is simulated. The presented model successfully shows three distinct stages of a cutter roof in a shale roof: (1) initiation of shear cracks at the rib– roof intersection, (2) extension of cracks deeper into the roof (i.e., above the roof bolt length horizon), and (3) cantilevered roof. It is demonstrated that the presented constitutive model has the potential to help future researchers in simulating various roof responses.

Jul 1, 2023