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By Bruce J. Barker

"Environmental concerns have recently been growing over the disposal of reactive desulphurizing slag. Consequently, increased pressure has been placed on the foundry industry to reduce the reactivity of this slag.To address this problem, Cyanamid has developed a new product which significantly reduces the calcium carbide content of the desulphurizing slag. Testing equipment and procedures have also been developed to evaluate both the existing levels of carbide in the slag and the decreased levels which are achieved with this new material.The development and use of this engineered carbide desulphurizer has made possible significant environmental and efficiency improvements in the field of calcium carbide desulphurizing. Consequently, the lifespan of calcium carbide in ductile iron desulphurization has been increased, as have the benefits of its use in the foundry industry. IntroductionIn the production of ductile iron, calcium carbide has long been used for hot metal desulphurization external to the cupola. Its cost effectiveness, reliability and ease of use have traditionally made it the desulphurizer of choice for a great majority of ductile operations. Recently however, environmental concerns have been raised regarding the quantity of calcium carbide remaining in the slag after desulphurizing. Analysis has shown that as much as 25070 of the weight of the slag may contain active carbide. This has caused disposal concerns as calcium carbide when in contact with water, produces acetylene via the following reactionr:"

Jan 1, 1992

By Patrice Nadeau, Yuejun Zhang, Dan Chen, Liming Huang, Claude Gagnon

"The traditional Denver flotation cell is generally suitable to process material ranging approximately from 5 µm to 300 µm. For floating over 300 µm material, its efficiency is significantly getting lower mainly due to the difficulty to suspend coarse particles uniformly, which decreases the chances of particles to attach to bubbles and increases the chances of detachment.RTFT (Rio Tinto Fer et Titane) owns one of the world’s largest hemo-ilmenite deposits. Considering the whole processing technology, the ore is only crushed to -1180 µm. The crushed ore contains about 0.32% S and most of the sulfur is removed by rotary kilns in the ore preparation plant. In order to achieve a similar S reduction, without emitting SO2 into the air, an alternative technology by flotation was pursued.Laboratory and pilot scale-up tests showed that traditional Denver flotation cell could perfectly remove the sulfur from the material sizing 0-300 µm. For the coarser particle sizes, two different models of equipment were tested to improve flotation efficiency: HF (HydroFloat Separator) from Eriez and CLF from BGRIMM (Beijing General Research Institute of Mining and Metallurgy), China. The D6” HF, which is a device that combines flotation and gravity separation, demonstrated its ability to recover those very coarse particles. As compared to the Denver flotation cell, the modified 25 L CLF coarse particle flotation cell achieved better results at higher pulp solids percentage and with a shorter flowsheet."

Jan 1, 2016

By Roger D. Plouffe

In today's mining industry, it is possible to retrieve, from small-diameter holes, geophysical data for qualitative interpretation in exploration and quantitative interpretation in the development of orebodies. The primary objectives in the exploration stage are to identify where, within a hole, economic minerals are, and to help in lithological interpretations. Other aspects, which are more quantitative, are the interpretation of downhole logs for parameters which can be used in surface geophysical methods (i.e. density for gravity surveys, acoustic velocities for seismic surveys, and magnetic susceptibility for airborne and ground magnetic surveys). Recent advances in equipment design, portability and durability have made downhole logging in exploration more inexpensive and reliable. This new equipment is being used to generate very precise quantitative results. This is especially true on uranium development projects. The interpretation of gamma logs for eUJOS values has finally become precise enough that they have begun to replace chemical values in reserve calculations. Another part of development data is density and equilibrium information, which, with today's technology, is being derived from downhole probing. In the years to come, the trends for many metals are toward neutron activation techniques, or "in-situ assaying", and the use of multiple logs for better lithological and physical rock property determinations.

Jan 1, 1981

By P. S. Daly

"The purpose of this paper is to describe the types of instrumentation used at Sherritt Gordon's Ruttan Mine to monitor the"" effects of mining. The aim of the monitoring program is to establish parameters to achieve a maximum ore recovery with minimum dilut ion in a safe environment.The copper-zinc Ruttan Mine is in northwestern Manitoba, approximately 760 km from Winnipeg (Fig . I) . Production commenced in 1973 from the open pit at the rate of 10,000 tons per day. Pit bottom lies 58 metres above the first mine level. Underground development has overlapped with open-pit mining throughout. The open pit was phased out in the latter part of 1980.Underground production began in early 1979. The mining method employed in the first lift is sub-level blasthole open stoping with delayed hydraulic filling. Large-diameter (6.5-in.) holes are being drilled in the crop stope area and are also planned for some other areas for vertical retreat mining into a slot. GeologyThe orebody consists of numerous sulphide lenses of variable size, geometry and geology . The lenses occur within volcanoclastic host rocks which exhibit a strong variability in intensity and type of alteration and structural characteristics. Stope design and sequencing were based on these complex geological factors."

Jan 1, 1981

The mixer that is commonly encountered in hydro metallurgical operations consists of a single turbine and tank combination. However, it would be advantageous to examine some common solvent extraction mixing systems in the light of the fundamentals of chemical reactor design. The basic concepts of reactor design are commonly used in the chemical industry, and it should not be too difficult to apply them to solvent extraction. The factors that affect the engineering design of a reactor are: the reacting system; the type of reaction; and the configuration of the reactor. The reaction system in solvent extraction consists of a heterogeneous liquid phase, involving two immiscible liquids. It is essential f or the process that the reactor product can be separated efficiently in the subsequent settler. The type of reaction in solvent extraction system may be quite complex, and the picture is complicated by the presence of competing and side reactions. The reactors themselves have been generally continuous stirred tanks, and the nature of the mixer-settler makes it unlikely that the pumping mixer can be dispensed with. However, it appears that there should be some definite advantages to a system of stirred reactors in series. The kinetic experiments which are carried out should have the definition of optimum reaction conditions as one of their goals. The data obtained from these experiments must also be applicable to the design of reaction equipment. Reactor selection and design is often a unique problem for each chemical process, and does not lend itself to a systematic general approach. However, the application of chemical and physical principles to mixer design in solvent extraction should result in practical, more efficient plants.

Jan 1, 1979

By E. G. Parker

"Sherritt's zinc pressure leaching process converts zinc sulphide concentrates directly to zinc sulphate solutions and elemental sulphur. Thus, one pressure process step replaces both the roasting and leaching operations of the conventional roast-leach route. In addition, high single-pass extractions eliminate the need for residue treatments to recover unleached zinc. Because pressure leaching produces elemental sulphur, rather than sulphur dioxide, acid plants and smoke stacks are not required, and air pollution control and work-place hygiene are greatly improved. .In 1977, Cominco Ltd. and Sherritt Gordon Mines Limited jointly operated a three-tonne-per-day pilot plant to demonstrate pressure oxidative leaching of Sullivan zinc concentrate and the subsequent separation of elemental sulphur. The process consisted of regrinding the concentrate, continuous leaching at 150°C at elevated oxygen pressures in a four compartment autoclave and the subsequent recovery of elemental sulphur, either in the molten liquid form from a decantation autoclave or as a flotation concentrate. Of the zinc contained in the concentrate, 97% was extracted in 90 minutes, and 96% of the sulphur was converted to the elemental form.Following the successful pilot campaign, Cominco began building the world's first commercial zinc pressure leaching plant. This plant, which was in operation by late 1980, will eventually treat about 25% of Cominco's planned zinc capacity of270,000 tonnes per year.This paper describes the general process principles, the results obtained from the pilot plant and the integration of the process into Cominco's operations at Trail. The application of pressure leaching to a ""grass-roots"" plant is also discussed, and compared with conventional roast-leaching."

Jan 1, 1981

By G. A. Davidson, P. G. Williams

"New developments in centrifugal slurry pump technology are discussed in relation to their importance for improving pump operation and reliability.Experimental data obtained by measuring the velocity of liquid flows in a slurry pump casing using Laser Doppler Velocimetry are presented. This demonstrates the importance of selecting pumps with the proper hydraulic design to provide optimum efficiency, maximum part life and minimum operating cost.The paper also discusses the use of new wear resistant materials, such as ceramic/metal composites, which can significantly improve the life of parts exposed to abrasive media. The results of laboratory attrition tests are presented. IntroductionCentrifugal slurry pumps are of primary importance for the hydro transport of abrasive and corrosive media in the mineral processing industry. As for all process equipment, slurry pumps must be carefully selected and operated to provide optimal performance. To achieve this, it is necessary to select equipment which will provide efficient and reliable operation for the specific service conditions and incorporates the best materials available to obtain maximum parts life.Abrasive wear of liquid end components is the most important aspect that distinguishes the design and application of slurry pumps from other types of pumps. It is therefore necessary to have a fundamental understanding of the mechanical interaction between pump components and the media being handled, as this will impact significantly on hydraulic design, mechanical reliability and selection of wear resistant materials. Recent advances in computational approaches'» have greatly improved the prediction of wear rates in pump casings by facilitating the solution of complex equations which describe the wear mechanisms mathematically. In conjunction with this, new experimental techniques allow researchers to measure flow fields in pump casings using non-invasive devices such as Laser Doppler velocimeters."

Jan 1, 1992

By J. Stachulak, M. Scobie

"This paper addresses the occurrence and indicated causes of conveyor fires in North American and European underground mines. Some significant convey or fires which have been experienced in recent years in Canadian hardrock mines are then reviewed. The nature of existing conveyor monitoring technology is considered in the context of such fire hazards. Experiences with new monitoring technology recently installed at several conveyor sites at Inca Ltd. mines are then reviewed.IntroductionFires associated with conveyors have long been recognized as a serious hazard in underground coal mines. Recently, however, there have been some significant conveyor fires in Canadian underground hardrock mines. These offer important evidence as to the nature and causes of potential hardrock mine fifes. They also warrant attention with a view to improving over-all mine design, ventilation and emergency preparedness.In addition, a new era in mine communications and monitoring technology has been entered which should offer improved capability to protect against such fires. This paper was motivated by the need to understand the causes and mechanisms of conveyor fires in order to improve their safety. This should be possible through implementing more effective monitoring systems, as well as improving conveyor design. Underground mines are becoming more intensively mechanized, with less human surveillance of equipment and a greater dependency on remote monitoring systems."

Jan 1, 1992

By C. J. Mwenifumbo

Preservation of groundwater quality is a major environmental concern. The disposal of hazardous material from urban waste dumps, milling wastes in tailings ponds, and industrial wastes in injection wells may contaminate potential sources of potable groundwater. The containment or migration of contaminants in the subsurface depends on bedrock characteristics and type of overlying sediments. Fractured bedrock and permeable sediments that may provide pathways for the transport of potentially harmful contaminants should be avoided when selecting a disposal site. The role of borehole geophysics in hazardous waste-site investigations is reviewed in three categories: (I) site selection; (2) determination of the extent of contamination at existing sites; and (3) long-term monitoring of migration of contaminants. In the first category, borehole geophysical techniques developed for lithology and fracture identification, and for porosity determination, provide some of the necessary information for understanding the subsurface hydrogeology. Lithological information can be obtained from gamma-ray, electrical resistivity, induction, magnetic susceptibility, and sometimes induced polarization logs; fracture detection and characterization can be accomplished with the use of caliper, density, resistivity, temperature, and acoustic televiewer logs. Estimates of porosity are derived primarily from neutron-neutron, resistivity, density, and soniclogs. Borehole geophysical techniques used in water quality determinations include self-potential, fluid resistivity, Eh (redox potentials) and pH measurements, and these can be used to map the extent of contamination at an existing waste site. Cross borehole and borehole-to-surface electrical methods can also be used in this application. Long-term monitoring of contaminant migration in boreholes can be accomplished with techniques that respond to changes in electrical conductivity, temperature and fluid chemistry caused by the presence of contaminants.

Jan 1, 1993

By B. E. Jones

"The area of uranium deposition is situated within the Churchill Province on the western edge of the Wollaston Iithostructural domain where it underlies the eastern edge of the Helikian Athabasca Formation. The Collins Bay deposit is 6 miles north-northeast of the Rabbit Lake mine. Two principal zones of uranium mineralization are described.The ""A"" zone is a partly eroded, high-grade pod of metal oxide and arsenides sheathed by clay-like minerals. It trends north-northeast and lies under 25 to 40feet of water. Uranium mineralization is localized at or adjacent to the unconformity between the Athabasca Formation and the basement rocks. The basement comprises a granitoid Archean terrain overlain by paragneisses of the Aphebian Wollaston Group. ""A "" zone ore contains phyllosilicates, quartz, pitchblende, rammelsbergite, pararammelsbergite, carbonaceous material, galena, gersdorffite, niccolite, carbonate and a trace of sphalerite.The ""B "" zone lies 6,000 ft south of the ""A "", and subcrops under till cover. It is a partly eroded zone composed of metal oxide and arsenides which occur within variably altered Athabasca Formation. Minerals recognized are phyllosilicates, pitchblende, niccotite, gersdorffite, millerite, carbonaceous material, pyrrhotite, skutterudite and a trace of galena. The Athabasca Formation varies from 90 to 160ft thick. Granitoid gneisses of probable Archean age and paragneisses of the Wollaston Group underlie the deposit. An easterly dipping thrust fault transects its length.The deposit is typical of the ""unconformity-type"" uraniumnickel deposits of the Athabasca Basin. Observed features fit well with the ""diagenetic-hydrothermal"" model for such deposits, as envisioned by Hoeve and Sibbald (/978)."

Jan 1, 1980

By M. A. T. Cocquerel, J. G. Eacott

"Simulation techniques may be used to optimize existing processes and plant operations, and in plant design at the engineering study stage of a project . This paper describes the latter application, using a computer, to optimize the concentrate stockpile requirements of a modern copper smelter.A large open-pit mining operation is envisaged and it is assumed that copper concentrate is smelted in two flash furnaces. The proposed mining plan gives rise to metaffurgical considerations in smelting which dictate that concentrate blending is carried out in the early years of operation in order to eliminate wide variations in the grade of concentrate charged to the furnaces . Stockpiling facilities are therefore necessary for blending purposes and also to provide a strategic reserve of concentrate to ensure continuity of concentrator and smelting operations.The objective of the study is to determine the optimum size of concentrate stockpile required to take account of both metaffurgical and strategic considerations. Two separate simulation models are developed to achieve this objective. The first model is used to determine the minimum size of stockpile necessary for blending purposes to smooth out variations in concentrate grade between 15 - 60% Cu, with associated 34 6% Fe, respectively, and ensure that the concentrate fed to the furnaces does not faff below 12% Fe, which is considered a minimum for good smeltability.The second simulation model covers a projected three-year operating period and indicates the maximum size of stockpile which is likely to develop during scheduled and unscheduled shutdown periods in the concentrator and smelter.Covered storage volume and conveying facilities for the optimum size of concentrate stockpile can be designed based on the results generated by the simulation models."

Jan 1, 1980

By C. Tan, A. Putz, P. Lacombe, R. Kemp, M. Kaya, B. J. Huls, A. R. Laplante

"This paper concentrates on the four recent plant trials/ applications of froth washing. Results showed that improved metallurgical performance can be achieved with wash water. Increased froth cleaning yielded better upgrading, and some cases slightly improved recovery. Froth sampling and salt tracer tests supported the findings of froth washing tests.At Falconbridge, Ni grade increased from l.47% to 2.15% and recovery from 85% to 87%. At Eastmaque, final Au grade increased from 2.3 to 2.7 oz/st at a slightly higher recovery. At Les Mines Selbaie, Cu grade increased from 24.5% to 25.S% and Zn grade from 54.5% to 56.l%. At Zinc Corp. of America, average Zn grade increased from 55% to 56. 8% at the same recovery for a 45-day period. A number of plants in Canada and the United States have evaluated and/or now practicing froth washing. Wash water has now proved itself in some plants over several months of operation.INTRODUCTIONFroth washing in mechanical flotation cells offers a number of metallurgical (i. e. increased grades and/or recoveries) and economical (i.e. decreased transportation and smelting & refining costs) benefits. Fundamental development work in laboratory and pilot scales performed at McGill yielded encouraging results. (Kaya and Laplante, 1988a and 1989a). Since laboratory and pilot flotation performance can differ from full-scale due to differences in hydrodynamics, kinetics, and froth characteristics (e.g. stability, loading etc.), plant trials were essential to prove the viability of this technology."

Jan 1, 1990

By Susan W. Campbell, Bruce Regensburg

"The CIM Careers Task Force has addressed industry's concern of a perceived shortage of skilled personnel over the coming decade. The industry is faced with a fundamental shift by young Canadians away from scientific and engineering careers, coupled with the fact that today 's students know little about the minerals industry and have a poor image of it.The responses to two questionnaires which were distributed to CIM members, government, professional associations, and educational institutions, formed the backbone of the Task Force position paper, which presents a shopping list of ideas and initiatives for consideration and to facilitation by the various organizations concerned.Tackling the image of the minerals industry is part of the answer to the careers crisis. On the positive side, the minerals industry provides the allure of a treasure hunt for young people and is seen as a significant contributor to the economy. It is understood to be well paying, provide good opportunities for advancement, individualism, and travel, and to be rich in esprit de corps. Enhancement of these positive aspects of the image can take place at all student age levels.Numerous initiatives tackle the negative aspects of the image. Young people perceive the industry to be environmentally damaging, which is the most crucial aspect that needs to be addressed. The industry is seen as still in the pick-and-shovel days and as a sunset industry that is running out of ore. Work in the minerals industry is perceived as dangerous and lacking glamour. And finally, the perceived remoteness of operations and exploration is seen as a drawback to a largely urbanized student group.Tackling young peoples' curiosity and interest in the minerals industry throughout grade school and encouraging postsecondary science and engineering students to enter the minerals industry by ensuring summer employment is the second part of the equation.The CIM Careers Task Force position paper develops strategy to attract and maintain interest of students in grade school, junior high, senior high school, and in post-secondary levels. The strategy outlines initiatives targetted at each of the educational levels and action plans to accomplish the objectives."

Jan 1, 1993

By Yu. V. Ponomarenko, A. I. Meka, P. A. Witherspoon, Yu. I. Volkov, J. E. Gale

"The mining of iron ore in the Kursk Magnetic Anomaly (KMA) region of the U.S.S.R. is done mostly by the open-cut method. An assembly of open pits capable of producing about 100 million tons of ore per year makes KMA the largest iron ore field in the world. Three gigantic open pits are currently in operation: Lebedinsky, Mikhailovsky and Stoilensky. These pits are as large as 13 km2 on the surface and as deep as 230 m. The mining operations are constantly faced with the problem of flooding from aquifers that overlie the orebodies; the magnitude of the problem is evident from the fact that the present groundwater inflow to these three pits is about 110 million mt /yr.Under such conditions, safe operations and pit wall stability are of great importance, and this has been accomplished very effectively by the appropriate use of seepage barriers and drainage systems. At KMA, the most important items used in the system of groundwater control are standard pumping wells, raise wells that drain into a 20 km to 30 km long underground drift located just outside the perimeter of the pit, horizontal wells driven through the pit walls, and horizontal drains. This paper describes the mining and engineering technology that have been developed at KMA to control the groundwater systems and protect the mines from flooding."

Jan 1, 1992

By M. C. Villeneuve, P. A. Siratovich

We present an integrated analysis of laboratory-based thermally induced fracturing and results of numerical models to give insight to the role of thermal shock fracture on geothermal reservoir rocks. Thermal stimulation is a reservoir permeability enhancement technique applied to commercial geothermal reservoir rocks to enhance fluid injection capabilities for spent power plant working fluids. The process is well known to enhance permeability but the thermodynamic and physical constraints of the process are less certain. In an attempt to constrain the interaction and the ideal conditions that lead to permeability enhancement, experimental procedures were carried out to mimic the conditions that a reservoir rock would experience during a thermal stimulation using temperature differentials ranging from 50-300°C. Samples underwent such thermal gradients under controlled laboratory conditions and were characterized for the changes to permeability, porosity, ultrasonic velocities, dynamic elastic moduli and petrological changes. The thermal stimulation was simulated in a FLAC2D thermal numerical model to investigate the nature of the thermally induced changes in the sample. The development of this model also allows us to investigate the relationship between geological characteristics and the ability to thermally stimulate any type of rock. The results indicate that numerical thermal shocking experiments are corroborated by laboratory-based results. The implication of this study is that the refined numerical models present an insight to the conditions and constraints under which thermal stimulation can prove to enhance permeability that could not be gained through purely laboratory-based studies.

Jan 1, 2015

By J. L. Dion

"A study of the techniques to integrally cast copper tubes in copper tuyeres for use in blast furnaces has been carried out. The work has been performed in support of current efforts to produce two-compartment tuyeres having improved water-cooling capacity. A test pattern corresponding to a vertical section of a two-compartment tuyere, and including a cast-in-place copper tube, was used to investigate such variables as tube preparation, tube coolant, pouring temperature, pouring rate and gating design. Successful castings, either with a good metalfurgical bond or good intimate contact between the tube and the casting, were produced, with all combinations of gating system and position of the tube tried. However, the pouring temperature, the pouring rate and the effectiveness of the coolant are interrelated and must be controlled to produce a good metallurgical bond.IntroductionAs part of its contribution to, and in collaboration with, the Copper Casting for the Steel Industry Committee, CANMET has undertaken research into the methods and techniques needed for the integral casting of copper tubes into high-conductivity copper castings.The objective was to produce two-compartment copper blast furnace tuyeres in which the water-cooled nose compartment consists of a copper tube metallurgically bonded to the wall of the high-conductivity copper casting. This design, developed in the UK, has demonstrated a much extended service life with attendant economies; unscheduled shutdown of blast furnaces due to tuyere failure is a significant problem in the steel industry. The Canadian steel industry believes that this design will replace the currently used single-compartment tuyere in blast furnaces within a few years.The technology to produce these tuyeres does not exist in Canada. One of the main features is the inclusion of a smooth-walled cooling channel in the nose, which permits high velocity cooling water to be employed. A second compartment acts as a reservoir backup, should failure in the nose occur. This would allow continued use of the tuyere for a period of time, permitting a scheduled shutdown for repair s. To assist the Canadian producers of tuyeres to maintain their market, and the Canadian steel industry to have a reliable domestic supply, it is important that the necessary technology for the production of two-compartment tuyeres be developed and transferred to industry."

Jan 1, 1982

By Alan F. Stewart, Frederic B. Claridge, Robert S. Nichols

"In recent years, an increasing number of mines in mountainous terrain have examined the possibility of placing mine waste rock into stream valleys. Pressure to utilize stream valleys as a primary location for waste disposal has increased at many of the mines currently under development or expansion. As the number of environmentally and economically ideal wastedumping sites is limited, consideration must be given to utilization of stream valleys. This raises concerns about maintaining water quality in streams passing through or beneath the dumps and potential detrimental effects to dump stability. Commonly, the flows in the streams tend to be flashy, reflecting localized intense storms and rapid runoff in steep-sided slopes within the watershed. These conditions pertain particularly to British Columbia, which is characterized by mountainous terrain and periodically intense precipitation events.The method of conveying flow through a waste dump depends on a number of geotechnical and hydrological factors, including the size, durability and transmissivity of the rock and the design stream flood flow. This paper describes the approach to the design of waste dumps in stream valfeys developed at several mines in British Columbia."

Jan 1, 1986

By Yongfeng Jia, Shaofeng Wang, Danni Zhang

Ferrihydrite is ubiquitous in soils, groundwater and aquatic sediments and is usually classified as "2-line" or "6-line" according to the number of diffuse XRD peaks. It has high surface area and reactivity; therefore, it may serve as a sink for sequestering trace metals, metalloids and organic matters via adsorption and co-precipitation. Although considerable attention was paid to the transformation process of this thermodynamically metastable solid, there are still some controversies on the mechanisms of the formation of goethite or hematite from the ferrihydrite precursor. This work systematically investigated the transformation of 2-line ferrihydrite produced by using different neutralization regent (CaO vs. NaOH) into crystalline products at different pHs (4, 7 and 8), three temperatures (25, 40, 75 °C) and in different media (sulfate vs. nitrate). X-ray diffraction (XRD), Raman, Fourier transform infrared spectroscopy (FTIR) and chemical extraction were employed to characterize the transformed solids as well as the redistribution of Fe between the amorphous and more crystalline phases. The results showed that the transformation product in nitrate media was hematite (major) and goethite (minor), which was independent of pH, temperature or neutralization reagent. In sulfate media, goethite was the dominant solid under slightly acidic conditions (pH 4) with 6-line ferrihydrite as the intermediate product, whereas neutral to slightly alkaline conditions still favor the formation of hematite. Chemical extraction results indicated that there was only ~3 % of amorphous phase detectable after aging at 25 °C for 280 days at slight acidic pH. In contrast,~70 % of the iron remained as an amorphous phase under neutral to slightly alkaline conditions. The results suggested that the pH as well as the reaction media (sulfate ion) plays an important role in the 2-line ferrihydrite transformation process.

Jan 1, 2016

By T. Grammatikopoulos, A. Jordens, C. Gunning

"Exploration activity for rare earth element (REE) deposits (i.e., alkaline complexes, carbonatites) has increased significantly in the last decade. A number of deposits have been evaluated around the globe. However, new mines have not been commenced in the last few years with the exception of Mount Weld (Lynas) and Mountain Pass (Molycorp).Resource estimation of REE can follow similar guidelines to other metal projects. However, the inherent mineralogical characteristics of the REE deposits, despite their complex nature, have been generally overlooked by many exploration companies. These include variability of the ore, liberation and association of the REE minerals, and grain size, all of which can affect the processing of the ore. Each deposit appears to be different in terms of matrix and REM (rare earth minerals). Light REE bearing minerals such as allanite, monazite, bastnaesite, synchysite, and HREE bearing minerals such as fergusonite and xenotime can vary widely in composition, grain size and association (e.g., carbonates or hard silicates). On the other hand, although not really REM, zircon, Zr-silicates, titanite, fluorite, apatite, and in some cases many other common silicate minerals can carry trace to significant concentrations of REE.The evaluation of REE deposits should include an appropriate mineralogical characterization in order to quantify the REM, distribution, liberation and association by quantitative mineralogical techniques (i.e., QEMSCAN, MLA, TIMA and others); chemistry of the REM by electron probe micro analysis (EPMA), Laser Ablation ICP-MS or ToF SIMS.These techniques provide valuable data for geological purposes such as: defining quantitatively, the variability and distribution of the REM; differentiating between LREE and HREE zones to delineate ore; and metallurgical purposes to predict minerals/REE behaviour during processing. The lack of a comprehensive mineralogical characterization often leads to the wrong processing path and ultimately affects the elemental/mineral recovery."

Jan 1, 2016

By R. G. Gillies, C. A. Shook, W. H. W. Husband

"The current state of knowledge concerning pipeline transport of coal in water slurry form is summarized for the four categories: coal-water fuels, conventional fine coal slurries, coarse coals and stabilized mixtures of coarse and fine particles. Surface chemistry is of dominant importance for coal-water fuels and considerable progress in understanding the role of surfactants has been achieved in recent years. Little generalized research on the flow of conventional fine coal slurries has been done in the past 17years, although innumerable conceptual designs and feasibility studies have been undertaken. Coarse coal slurries are fairly well understood but the model which explains their flow requires more data to be established fully. Stabilized flow mixtures should probably obey the same model as coarse coal slurries but experimental results for stabilized mixtures have not yet been incorporated in a comprehensive theory.IntroductionPipeline transportation of coal in a water vehicle has been employed for many years in coal washeries. It has been used less frequently in hydraulic mining and thermal power station fuel supply systems. The suitability of coal for pipeline transport arises from its moderate specific gravity relative to the carrier fluid and the fact that throughputs are often large and steady over long periods of time."

Jan 1, 1990