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By Abhilash

Uranium is conventionally extracted using a process that employs strong acid (H2SO4) and an oxidant (MnO2) as leaching agents. This method often creates environmental problems, requires large amounts of energy, and involves a complex operational plant. It is not, however, economically attractive to extract uranium from low-grade ores by chemical leaching. Because the content of U3O8 in the Indian ore is usually below 0.1% by weight, it is necessary to develop an alternative process to enable the efficient and economic recovery of uranium. Uranium ore from the Narwapahar mines, UCIL is a type of vein deposit found in India, which accounts for ~54% in India. The ore (0.047% U3O8), though of Singhbhum area, possess exceptionally different mineralogy due to presence of some refractory minerals and richness of apatite (5%) resulting in a maximum 78% recovery through conventional processing at UCIL, with a very high consumption of sulfuric acid and pyrolusite, besides possible loss of uranium as uranium phosphate. To avoid usage of environmentally non-benign oxidants, remediation of influence of phosphates, and improve the overall process output of uranium; an alternate extraction technology using microbial isolate(s) is worthwhile exploring and the same is presented in the paper. The microbial isolate enriched with Acidithiobacillus ferrooxidans grown from source mine water was employed for bio-leaching of uranium while varying pH, pulp density (PD), particle size, etc. On varying pH at 35oC using 20%(w/v) PD and <75µm particle size, 83.5% and 78% uranium bio-recovery were observed at 1.7 and 2.0 pH in 40 days against maximum recovery of 46% and 41% metal in control experiments respectively. Whereas, it was observed that grinding of ore to finer size actually helped dissolution of uranium. Finer size particles (<45µm) gave a maximum biorecovery of 93% in 40days at 10%(w/v) PD, 1.7 pH and 35oC. The bio-recovery of uranium fell down from 93% to 82.73% and 60% on increasing the pulp density from 10% to 20% and 30% respectively for particles of <45µm size. The higher uranium dissolution during bioleaching at 1.7pH can be correlated with increase in redox potential from 433 mV to 664mV in 40 days.

Aug 1, 2010

By G. Harper

"AbstractThe Suetut. Copper deposit, 230 miles northwest of Prince George, B.C., was discovered in August of 1971. Subsequent exploration has included 56,417 feet of surface diamond drilling in 139 holes. The deposit occur in gently dipping volcanic rocks of the Upper Triassic Takla Group, which out crops as rugged mountains.The general Mesozoic sequence comprises some 20,000 feet of green and red basaltic to andesitic rocks. The Lower Formation is characterized by subaqueous basalt, andesite and augite porphyry flows with interbedded breccias. They were rapidly deposited in tectonic depressions of limited extent and steep gradients. Facies changes are abundant. The Middle Formation. consists of volcaniclastic rocks made up of fragments from the underlying formation. Two cycles are discernible , both with basal turbiditic, tuffaceous sandstone and shale units overlain by massive, volcanic conglomerates exhibiting graded and cross bedding. A broader, shallower-water basin is indicated. The top of the uppermost unit was subaerially deposited. The Upper Formation is a variable sequence of volcanic sedimentary rocks. Detritus was supplied from a wide source area and included multiple reworked fragments of the lower formations and material from other rock groups known in the region. Zeolite facies metamorphism is recognized throughout: the entire sequence. Epidote is particularly abundant in the Middle Formation, demonstrating the results of metasomatism.The mineralized zone is approximately concordant with the strata over 100-200 feet of the Middle Formation succession . It lies just below the zone of transition from subaqueous to subaerial deposition in the top unit. Hematite, chalcocite, pyrite, bornite, chalcopyrite and native copper are disseminated throughout all sizes of lithic fragments and matrix. Concentration into the specific zone is believed to be due to upward leaching of copper during lowgrade metamorphic and metasomatic reaction. Precipitation occurred in the zone of hydration characterized by prehnite-pumpellyite below the oxidized subaerial rocks."

Jan 1, 1977

By W. S. Fyfe

Gold is mobilized and precipitated in a wide variety of environments ranging from those of weathering and biological phenomena, to pluton emplacement to deep metamorph ism . But it appear that pervas ive leaching of large rock volumes fo llowed by the focussed di charge of typically low salin ity flu ids is frequently involved. There are great gaps in our knowledge, particula rly with re pect to gold in very high temperature fl uids generated at near Moho depths. But uch flu id may play an important part in Archaean pluton associated lode gold deposits whe re ultra high temperature fluids, rich in C02-CO-COS, may be associated with magma underplating and crustal assi mil ation processes (sag subduction) associated with very den e ult ramafic magma . Other environment with great potential include those of major thru t fau lt and strike slip fa ult s where large quant ities of fluids are mobilized .

Jan 1, 1986

By J. M. Turnbull

THE primary objective of the young graduate, after the war, will be to obtain a suitable position within the Industry, with adequate pay and opportunity to advance. The positions available to meet this demand will depend on the magnitude and organization of the industry. The size of the mining industry, in particular, will depend on a number of factors, including depletion; new discoveries of mineral deposits; beneficiation of new kinds of mineral deposits, based on research; technical improvements, also based on research, enabling the mining of lower grade deposits; and complex social factors. The organization of the industry will depend on its control and management, which may be greatly affected by social conditions and changes, and may include a wider or a narrower use of technical services. The corresponding training or qualifications of graduates, to meet these conditions, calls for a consideration of educational requirements and facilities in relation to the conditions that are likely to occur. Some forecast of the probable future of the Industry, after the war, based on consideration of. the above factors, is necessary as a basis of discussion, since the graduate must find his place in the industry of that time, and find his work in maintaining and improving it, within the existent social framework. Social factors are pressing and? important at present and their future impact is uncertain. In considering these, a few quotations and extracts may be in order. "A new economic order, based on free access to the sources of raw materials, means free use of the world&apos;s wealth by all civilized nations" (The Pope. Also advocated by Churchill and Roosevelt in the Atlantic Charter). "Every citizen should have a voice in the conduct of business or industry which is ?carried on by means of his labour" (Archbishop of Canterbury).

Jan 1, 1943

By J. W. M. Porritt, M. P. Brameld, R. H. McCorkell

"Soil-gas Rn was measured by two types of alpha-particle-track detectors, by emanometry and by counting alpha-activity on Rn-decay-product collectors. Soil samples were analyzed for V by fluorimetric and fission-track methods, their Rn-emanation by decay-product collectors and their total alpha activities with track detectors. The same uranium anomalies were revealed by each method. Fission-track analysis of leaves for V showed only random variations with sampling site, and the Rn emanation of trees and leaves removed from them was barely detectable . The agreement among the other methods is significant, total alpha and collector methods are simple, rapid and useful, and a combination of methods at a site would reveal disequilibrium in the U-decay series if present. Track-Rn measurements are highly reproducible and insensitive to apparatus design and their sensitivity is not enhanced by covering the detectors with thin foil or placing them in large containers.IntroductionIn the past two years , a number of methods of geochemical exploration for uranium have been tested by the authors over the known copper-uranium occurrence at South March, Ontario. This was done partly to compare methods and partly to develop and test new ones. The South march deposit has been described a number of times by others(1,2,3,4). The methods included in this study were the following.Emanometry, Radon in soil gas is measured by pumping the gas into the cell of a scintillation counter or emanometer(5,6). Alpha particles from radon (222Rn) and its decay products (218Po and 214Po) produce scintillations of light in the silver-activated zinc sunphide (ZnS(Ag) covering the walls of the cell. These are counted by a photomultiplier tube and scaler, the count ra sulphide (ZnS(Ag) covering the walls of the cell. These are counted by a photomultiplier tube and scaler, the count rate being proportional to the concentration of radon in the soil gas."

Jan 1, 1981

By Eugene Barsky

"At present, theoretical concepts of gravitational separation processes are mainly limited by the study of the interaction between a flow and a solitary particle. Then the main conclusions of this analysis are applied to a mass process. However, this analysis is absolutely insufficient, because some elementary phenomena such as the ingress of coarse particles into the fine product output and vice versa cannot be interpreted from its standpoint. It is also impossible to predict the results of the classification of a material with a specific granulometric composition on a specific apparatus on its basis.In the present paper, an extended model of the process is suggested. The model is based on the behavior of all the particles of a specific narrow size class, and not on that of an individual particle. Similarity criteria of the process, which were empirically derived previously, are obtained from the analysis of this model.INTRODUCTIONIn case of gravitational separation, a part of solid phase moves, as a rule, vertically upwards with the flow, while another part settles against the flow. This flow is extremely complicated and chaotic due to various random factors. Among these factors are mass interactions of particles with each other and with the apparatus walls, non-uniform character of concentration and velocity fields, turbulent vortices and local fluctuations, real particles shape difference from spherical one, etc.Particles rotation results in a transverse force (Magnus' effect). At the motion of a non-rotating particle in a non-uniform velocity field, a transverse force also arises (Saffman's effect).A great number of publications have been devoted to the account for all these factors in two-phase flows in recent decades. Very complicated models have been developed, but the problem has not been completely solved as yet [1, 3].At the same time, simplified models of the behavior of a solitary particle in a flow are being developed. Despite their schematic nature, such models often prove to be useful for establishing general laws of the process and its similarity criteria [1]."

Jan 1, 2016

By Michael L. Free

The hydrometallurgy curriculum for undergraduate students at the University of Utah has evolved to contain a variety of tools to help students understand and apply hydrometallurgy in a context that has industrial relevance. In order for students to perform as engineers in an industrial hydrometallurgy setting, they need to understand thermodynamic and kinetic fundamentals and be able to apply these fundamentals to extraction, concentration, and recovery applications. Students must also understand related environmental, economic, and assessment issues in hydrometallurgy and be able to work with others. In order to meet these needs, the hydrometallurgy curriculum includes a variety of relevant subject information, on-line resources, laboratory experiences, and team work opportunities to help prepare students for careers involving hydrometallurgy. The development and use of these resources will be discussed in this paper.

Jan 1, 2014

By S. S. Teal, W. W. Weber

"AS THE TITLE implies, this paper will deal with the unusual rather than the standard practices as employed . at the property of North Rankin Nickel Mines, Limited. Fortunately •the mining, with the exception of permafrost conditions, and the milling practices, are the normal approaches dictated by the size, type, and character of the orebody. The unusual aspects are linked directly or indirectly to the isolated location and are •principally ancillary requirements or services covering a broad range from climate to supplies and from finance to entertainment. It is our intent to cover the more salient points of interest together with a brief description of the general operation.To understand the primary motivation of the mine, it must be made clear that North Rankin was conceived as a foothold in the Canadian North, that region embracing 40 per cent of the Dominion which ex-tends north of the commercial tree-line and which includes nearly 50 per cent of the Precambrian Shield, our mainstay of Canadian mining. Secondly, this project was born in an atmosphere of premium sales in the nickel markets, assuring a rapid pay-back of the heavy •capital expenditures. And finally, it has •been coddled through the stark reality of a competitive metal market with the hope and trust that the experiences and achievements will lead over the bill to a bigger and better mine in this virgin territory. This is the briefest story of the mine's history, but it pays tribute to the many people who, in thirty years since .discovery, have championed this project."

Jan 1, 1959

By R. Q. Honaker

It has been shown that naturally hydrophobic carbonaceous materials such as coal and graphite can be selectively coagulated and separated from hydrophilic impurities without using oily agglomerants, flocculants or electrolytes. The coagulation occurs at C-potentials significantly higher than those predicted by the classical DLVO theory, suggesting that it is driven by the hydrophobic interaction. In the present work, the energy barriers for the coagulation of a hydrophobic coal sample have been calculated using the extended DLVO theory which incorporates the hydrophobic interaction energy in addition to the dispersion and the electrostatic energies. For the coagulation of minerals present in the coal, the classical DLVO theory has been used for the energy barrier calculation. The results of these calculations provide an excellent correlation with the results of a series of Selective Hydrophobic Coagulation (SHC) tests conducted with run-of-mine coal and graphite samples.

Jan 1, 2004

By W. Graham

"IntroductionEFFLORESCENCE is herein considered to be any deposit of salts on the surface of a masonry structure that is brought from within or through the structure by capillarity and deposited by evaporation. Usually, efflorescence is white although green, yellow, and brown efflorescence is sometimes observed.The common white efflorescence almost always consists of sulphates of the alkali and alkaline earth metals and calcium carbonate, although sodium chloride is frequently present in structures erected near the sea shore.The first and most obvious result of the presence of soluble salts in masonry is the unsightly accumulation of these salts on the surface. This is particularly noticeable early in its life and is frequently fugitive ( 1), as much of the salt is soluble and is gradually washed away by rain. This removal can usually be facilitated by scrubbing; the structure with dilute hydrochloric acid.A more serious effect is the continuous accumulation of soluble salts as a result of ingress of sulphur acids in rain water or water from the ground. This may eventually cause spalling and disintegration by crystallization of salts in the pores of brick and mortar. An example of this type of failure, resulting from the crystallization of calcium sulphate, is discussed by Hardesty (2). Butterworth (3) describes similar failure resulting from •crystallization of magnesium sulphate."

Jan 1, 1954

By Thomas Mütze, Frank van der Meer, Gunnar Kretschmar

"The air classification of moist bulk materials is addressed in the literature insufficiently. Therefore a feasibility study investigated the influence of feed moisture on the separation efficiency expecting a reduction with higher moisture content in the feed. Two iron ore samples were characterized in terms of the nature of bonding of moisture as well as its effect on the agglomerate strength. The classification tests themselves were conducted with two dynamic laboratory air classifiers at cut sizes from 45 to 110 µm and a moisture of the feed material between 0 to 10 wt.-%. The quality of classification was assessed by split factor, cut size, separation efficiency, moisture of both products, as well as the yield of the fines as product fraction in a corresponding processing plant. An initial approach was found for a technological implementation: A sufficient drying of a moist feed can be realized simultaneously to the pneumatic transport inside the classifiers. In the present case the drying effect and dispersion intensity was sufficient to provide good separation results up to 3 wt.-% feed moisture. An additional drying step was necessary beyond 3 wt.-%.INTRODUCTIONSpecific information about the influence of moisture in air classifiers is very rare. Mostly only dry products are processed and/or drying prior to classification is recommended. Apart from the specific influence of the feed moisture a lot of literature can be found regarding air classification itself. Altogether air classification can be divided into several sub-process (Leschonski, 1977):- dosage of the feed material,- dispersing the solid feed material into a gas stream,- feeding the dispersed material into the classification zone by pneumatic conveying,- separation of coarse and fine particles, and- separation of fine particles from gas.For wet feed particles also drying plays an important role. Interesting for the present investigation are the humidity of the feed and its influence on the single sub-processes."

Jan 1, 2016

By Warwick D. Bullen

Gold mining in the Yellowknife area of the Northwest Territories started long before the concept of sustainability entered the academic literature and by the time the term enjoyed widespread public acceptance, the Yellowknife gold mining industry was in its sunset years. Nevertheless, the city of Yellowknife will long outlive the gold mines that it was founded on, demonstrating that not only can mining build sustainable communities, but that sustainable mining as a concept is an entirely valid precept. To this effect, the authors examine the complex economic and social aspects of the gold mining industry in the Yellowknife area over the last 70 years.

May 1, 2004

By Dean Gerhardt

Why the need for proactive loose detection? ?? Past history of ground falls in Saskatchewan mines prompted research into new techniques for ground control. ?? Traditional tools for ground assessment (i.e. visual inspection, sounding with scaling bars) are not proactive and can often be time consuming. ?? Need existed for a system that was non-evasive, time efficient, and could be managed by a single operator. Ground Penetrating Radar (GPR) immerged showing the greatest potential.

May 1, 2008

By R. A. Payant, J. A. Finch

Under certain conditions of air and moisture, sulphide materials can spontaneously heat, or selfheat. The reaction mechanisms of self-heating are not well understood. Most previous work has involved pyrrhotite because it is the most reactive sulphide. The current work investigates the self-heating behavior of sulphide mixtures composed of sulphides other than pyrrhotite. The four studied sulphides were pyrite, chalcopyrite, sphalerite and galena. The rest-potential was measured for each. Binary mixtures formed as a 1 : 1 weight ratio were pyrite-galena, chalcopyrite-galena, pyrite-chalcopyrite and chalcopyrite-pyrite. The four sulphides and the binary mixtures were subjected to standard self-heating tests. The four individual sulphides did not self-heat. However, mixtures of pyrite-galena and chalcopyrite-galena with rest-potential difference (?E) >0.3 volts did self-heat while the mixtures of pyrite-chalcopyrite and chalcopyritesphalerite with rest-potential differences (?E) = 0.1 volts did not self-heat. The results demonstrate that when certain non self-heating sulphides are combined they can self-heat. A possible explanation based on galvanic interaction and formation of hydrogen sulphide as an intermediate product is discussed.

Jan 1, 2009

In the flotation of a copper ore, entrainment of fine silicate and iron sulfide gangue minerals resulted in poor copper concentrate grade. In the cleaning stage, rejection of these gangue minerals was particularly difficult due to severe mechanical entrainment when the rougher concentrate was ground to 10 µm. To reduce gangue entrainment, polymeric depressants were tested. The rationale being that with the use of such polymeric depressants that also possess flocculation power, not only minerals-to-be-depressed can be made hydrophilic, but their particle size can also be enlarged. In this manner both the "genuine" flotation and the mechanical entrainment can be reduced. An effective polymer to reduce entrainment of silicate gangue mineral in sulfide flotation was identified from bench flotation tests conducted on single minerals. It was then applied to the flotation of a copper-gold ore confirming the beneficial role of the polymeric depressant in the reduction of fine gangue entrainment.

Jan 1, 2007

By C. C. Li

The D bolt is a new type of energy-absorbing rock support element recently developed in Nor-way. The D bolt is not only able to accommodate large rock deformations, but can also provide a load-bearing capacity as high as that of rebar bolts. Furthermore, the anchoring quality of the D bolt is similar to rebar bolts because of its multi-point anchoring design.

May 1, 2009

Applying DEM to prediction of tumbling mill performance is challenging because several different modes of breakage are active in the process. As our knowledge of breakage and computational capacity improve, it is worth revisiting previous simulation tasks which did not produce a satisfactorily realistic description of a measured process. At SAG 2006, we reported the simulated and measured outcomes of treating a well characterised ore in a 1.2 m diameter mill. This well instrumented, pilot scale mill at the University of KwaZulu-Natal has been combined with some new approaches to ore testing to allow different modes of breakage to be tested. The mill design allows the rate of generation of fine material to be measured in close to real time for autogenous and SAG mill charges. The updated simulation model estimates mass loss with particle evolution and embeds the cumulative damage and breakage. The simulated results are compared with the measured results. Issues such as relating modelling inputs to particle breakage characterisation data and the accuracy of the predictions of the models are discussed.

Jan 1, 2012

By Z. B. Karshigina, Ye. G. Bochevskaya, E. A. Sargelova, Z. S. Abisheva

At the present time of depletion of reserves of high grade rare earth deposits, it has become necessary to involve low grade raw materials in the production. Among the rare-earth deposits in Kazakhstan, the most advanced one is Kundybai. The mineralogical composition of ore is represented by the minerals: a-quartz SiO2, kaolinite Al2(Si2O5)(OH)4, muscovite KAl2(AlSi3)O10(OH, F)2, albite Na(AlSi3O8), rutile TiO2, and hematite Fe2O3. It contains: 59.1–68.5% SiO2, 19.1–28.4% Al2O3, 7.2–10.3% Fe2O3, 0.51–0.84% TiO2, 0.10–2.32% CaO, 0.39–2.10% MgO, and some other elements. Rare earths are located in the clay part (kaolinite, goethite) in the ion-adsorbing form, and they are represented by the main ore mineral churchite - YPO4·2H2O. In the ore the amount of rare-earth elements (total REEs) varies from 210 to 600 ppm. Elements of the cerium group predominate (La, Nd, Ce, Sm, Pr) and the yttrium group is represented by Y, Gd and Dy. Extremely thin intergrowth and accumulation of REEs in clay minerals cause difficulties in their recovery using flotation and gravitation beneficiating methods. The purpose of this work is the development of an extraction method for the main mineral components of ore with transfer of the total REEs into the solution with high extractive efficiency. Results of the experimental work into high-temperature processing (hereinafter referred to as sulphatization) of ore by sulphuric acid with subsequent dual-mode water leaching of the sulphate product (sinter) are presented in this manuscript. The influence on the ore sulphatization process of some physical and chemical parameters: liquid-to-solid (L/S) ratio (0.36–0.86 cm3/g), temperature (100 – 500°?), concentration of sulphuric acid (3.0–18.62 mol/L) and duration (0.5–2.5 h) was studied. Optimal technological parameters of the process were determined to be: L/S ratio 0.36–0.46 cm3/g; temperature 500°?; concentration of H2SO4 9.0 mol/L; soaking time 1.5 h. Under these conditions it is possible to obtain extractions of ~ 85% REE, as well as 58% aluminium and 10% iron. XRD and IR-spectroscopy analyses were used to determine the material constitution of sulphated cakes obtained under optimal conditions. It was found that the primary minerals are quartz and muscovite; however different sodium aluminium silicates and albite minerals are present as well. In the future, it is proposed that the leach residue cakes are processed into precipitated silica (“white soot”).

Jan 1, 2016

By A. G. Slade

"This paper deals with the direct application of rock mechanics in the underground mines at the Sudbury Operations of Falconbridge Nickel Mines Ltd. It covers mining methods, the use of photoelastic models, the fore-casting of rock strains and their elimination, closure methods and other common methods of ground control.INTRODUCTIONROCK MECHANICS IS A STUDY IN ROCK BEHAVIOUR and, although it is being termed a new science, it has been practiced since the industry began. Every person involved with rock excavations, from the mine superintendent to the stope driller, is actually practising rock mechanics. They probably call it by another name -experience, and applications of this knowledge are in evidence throughout the Falconbridge operations. Only in recent years have formal rock mechanics studies been employed to provide technical assistance to the mine operators in their primary objective of producing ore safely."

Jan 1, 1968

By S. Kelebek

Batch flotation tests were carried out using samples from stockpiles that were up to 1.5 months old as well as fresh samples oxidized in the lab for up to six months. Head grades and size distributions of samples were equalized whenever possible. The samples from stockpiles and oxidation experiments produced inferior nickel grade-recovery compared to the fresh sample. The poorer grade-recovery performance was attributable to two factors. First, a significant dilution effect was observed due to complete flotation of pyrrhotite. Secondly, the same stockpiling conditions caused nickel losses that were attributable to non-floatability of some pentlandite. Application of a high pH of 10 compared to the regular pH of 9.2 slowed down pyrrhotite flotation kinetics, but was not able to prevent complete flotation after 8 minutes. The samples oxidized in the lab did not match full characteristics of stockpile samples. They provided somewhat better selectivity for pentlandite. Some correlations were observed on a qualitative basis between surface characteristics such as elemental sulphur formation, activation and flotation behaviour. Oxidation conditions, which induce floatability on pyrrhotite while causing incremental loss in pentlandite floatability appear to be the root cause of difficulties in the processing of oxidized forms of these ores.

Jan 1, 2006