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By Hassan El-Shall, Ayman El-Midany, Patrick Zhang

Bench and pilot scale testing results suggest that significant improvement in dewatering characteristics of fine particles could be obtained by the addition of fibrous materials. Case studies involving flocculation and dewatering of wastes from phosphate, bauxite, and kaolin processing plants are presented in this paper. Several dewatering techniques were investigated, including sedimentation thickening, filtration, centrifugation, dewatering on screens, and seepage-induced dewatering and consolidation. Advantages and limitations of commercial application of some of the developed techniques arc discussed.

Jan 1, 2004

By Sydney H. Ball

It is a peculiar anomaly that while the world uses the term "rich as a gold mine" as the superlative figure of speech descriptive of wealth, the shares of gold mines are not as popular investments in America as certain of them should be. One of the most able of Manhattan's bankers is a director in an investment trust with a portfolio the value of which has gone the way of other such portfolios. Luckily a couple of years ago a few hundred shares of Homestake were purchased, and since then the trust has not only received therefrom satisfactory dividends but has benefitted from a large appreciation in their value. At each directors' meeting, however, the banker in question, Cato-like, suggests the sale of these shares, gold shares being, in his opinion, too speculative to be included in the portfolio of any trust. A short time ago the financial pages of one of our great metropolitan papers featured an article listing the corporations still paying dividends at the 1929 rate. Gold-mining shares were, the article stated, excluded, although in reality every gold mine on the New York Stock Exchange paid higher dividends in 1932 than in 1929. This 'Alice in Wonderland' treatment of the gold-mining shares is admittedly a bit confusing to those of us who believe that the shares of certain gold-mining companies have a rightful place in any well diversified portfolio. It should, however, here be recorded that whereas, fifty years ago, in America, gold-mining shares were considered by the public as instruments of nefarious gambling, now shares of the better gold mines are sought by astute investors. In England for well over a generation their value as sound investments has been widely recognized.

Jan 1, 1933

By Lev Filippov, Saeed Farrokhpay

"Flotation process has had less success to recover nickel from laterite ores. Nickel in laterite ores is often finely disseminated in various minerals in very fine size. Therefore, fine grinding should be used to liberate nickel containing particles. Particles resulted from fine grinding are often very fine, and recovery of such particles is generally low using conventional flotation methods. One option to overcome this problem is enhancing the particle-bubble interaction by increasing the particle size and forming flocs. Selective flocculation of fine particle can be therefore the key to enhance the flotation performance of low grade laterite ores.INTRODUCTIONThe majority of the world’s nickel resources occur as laterite ores which are complex, low grade and expensive to treat using conventional smelting and high temperature and/or high pressure autoclave methods (Xu et al., 2013). While about 70% of the nickel resources are contained in laterites, only 40% of the world’s nickel production comes from these ores. Researchers have tried to improve the nickel laterite flotation recovery by using a number of feed preparation techniques. For example, in a study on a laterite ore sample from Australia, flotation tests on a narrow sized fraction of 38-75 µm resulted in only a small increase in the nickel content, from 1.0% to 1.4% (Quast et al., 2015a). In fact, no physical separation technique (including flotation) has been able to dramatically upgrade nickel in laterite ores (Quast et al., 2015b). Thus the challenge of processing low grade nickel laterite ores still exists. This paper aims to explore the possibility of applying selective aggregation in pre-concentrating of valuable minerals in nickel laterite ores."

Jan 1, 2016

By K. K. Panthi, P. K. Shrestha

"Displacement of rock mass around a tunnel opening varies according to the rock mass properties, insitu stress conditions and applied support in the tunnel. Such displacement is also altered by presence of bands of rock mass that differ in properties. This paper focuses on the deformation behavior of rock mass around tunnel openings at four tunnel sections in Kaligandaki headrace tunnel where extensive instrumentation was done. Based on the actually measured tunnel displacement records and actually measured support pressure; back analysis has been done to estimate rock mass properties and insitu stresses. Numerical analysis has been done to analyze and assess the deformation behavior of the rock mass around the tunnel sections.INTRODUCTION Instrumentation and monitoring of tunnel convergences have significant importance in evaluation of tunnel stability. One of the key aspects of monitored data is that early convergences can be used in estimation of long term convergence. In addition, these data can also be used in evaluation of rock mass parameters and in-situ stresses around the tunnel. Convergence around a tunnel periphery may vary according to rock mass quality. Presence of bands of different rock mass may hinder the displacement pattern in the tunnel. Particularly, displacement characteristic of tunnel periphery in schistose, foliated and deformed rock mass is altered by presence of bands of comparatively stronger rock mass, e.g., quartz veins or presence of shear seams or faults. Similar observations were also recorded in monitored tunnel sections in Kaligandaki headrace tunnel, located in the Nepal Himalayas. Extensive monitoring was done by installing multiple point borehole extensometers (MPBX) at three different locations of the tunnel periphery at four different tunnel sections. In addition, convergence measurements by tape extensometers and installation of pressure cells to record support pressures were also carried out at each of the tunnel sections. Observations showed that the tunnel convergences varied according to rock mass quality, in-situ stress and effective support pressure.Rock mass parameters and stresses have significant role in the extent of tunnel deformation, but these parameters are often unknown or difficult to predict. Back analysis based on actual tunnel displacement records and known support pressure is believed to be an important method in such endeavor. This paper performs back analysis to evaluate rock mass parameters and discusses correlation of rock mass behavior with tunnel deformation and applied support. For this purpose, the rock mass parameters are estimated from actual tunnel displacement records, mapped rock mass quality records and laboratory tested data. Then, numerical modelling is conducted to correlate post peak behavior of the rock mass with actual tunnel displacement."

Jan 1, 2015

By Zhang. L.

Ordered intermetallic PtSb had been synthesized by arc-melted and then sintering treatment. The electro-oxidation of formic acid on PtSb was investigated at room temperature by cyclic voltammetry and chronoamperometry. The results are compared to those at a polycrystalline platinum electrode surface. It was found that PtSb intermetallic was catalytically more active than pure platinum according to the onset potential and current density. XRD and XPS technologies had been used to investigate the crystal structure and electron effect. We think formic acid decomposition on PtSb favors the reactive intermediate route and is not very much affected by the CO intermediate as compared to Pt.

Jan 1, 2005

By S. W. Marcuson, P. J. Mackey

The Canadian non-ferrous mining and metallurgical industry has made great strides in environmental protection during the past half century. The path taken by the copper-nickel smelting industry in reaching today’s level is traced in this paper. Following the practice at early copper smelters in Wales and in the US, Canadian smelters originally used tall stacks to disperse furnace of-gases. This was the normal mode of operation and was accepted by society and by Government. Gradually, Government regulations required fixation of sulphur dioxide emissions and Canadian companies responded with significant technical developments to achieve this result. The initial development in Canada of the first new technologies such as the Cominco Flash Suspension Roaster and the Freeman Flash Smelting Process - both representing early versions of the modern established flash smelting technologies - and then later technologies such as the Inco Flash Smelting Process and the Noranda Process, both of which continue to this day, are discussed in this paper in terms of their contributions to the development of environmentally friendly plants. The evolution of these and other technologies is also discussed. Some comments regarding how the industry will face the future are also included.

Jan 1, 2015

By Christopher A. Jacobs

Project managers aim to maximise the NPV of their projects, but don't always appreciate the relationship between mine throughput, project value and the discount rate being used to evaluate their projects. Rate of production or throughput is perhaps one of the most crucial decisions a project manager must make, but if this choice is made arbitrarily, much effort may be spent on a feasibility study that does not optimise project value. The timing of the study in relation to the stage of exploration is examined and simple techniques are presented that project engineers and managers can use to home in on a production rate which will give their project the greatest chance of success.

May 1, 2006

By N. Ahern, D. B. Dreisinger, G. Van Weert

In the thiosulfate leaching of gold, degradation of the thiosulfate reagent is a major cost. One of the intermediary degradation products is trithionate, which also inhibits gold recovery from solution by ion exchange. Little attention has been given to this species in the context of gold leaching - the limited information on trithionate and its solution chemistry available in the literature is seldom directly related to gold leaching conditions. This review is a compilation of the published knowledge on trithionate, with a specific focus on identifying the relevance of this information to gold leaching and the shortcomings in the knowledge base.

Jan 1, 2005

By Andreas Gaich

COMBINED 3D IMAGES _ Highly detailed 3D geometry _ Identification of fine fractures together with a general impression of the situation _ Dealing with unfavourable outcrop geometries

May 1, 2009

By R. S. Jones

"Fording Coal Ltd. is now in its fifth year of a 15-year contract to supply 3 million long tons of clean coal per annum to its Japanese steel-making customers. The mine employs both conventional truck-shovel and unconventional ""walking"" dragline coal mining techniques in multiple-seam pits. This paper describes the present and future application of the 60-cu.-yd dragline and truck-shovel pre-stripping fleet in 1•ecovering 5- to 40-footthick coal seams in mountainous terrain. Deep blastholes, coal flow demands, spring ""run-off"", seam and inter-seam thrust faulting, limited seam outcrop data and regional faulting are a few of the problems encountered in this application. The author discusses these problems and their solutions as applied at Fording Coal Ltd."

Jan 1, 1976

By W. E. Cockfield

This paper is not intended as an original contribution to this subject, but rather as a review of the main theories which are held with regard to placer deposits, with, of course, particular reference to the placers of British Columbia. The present interest in gold mining has, however, brought the subject of placers to the fore, and possibly a brief outline of the geology of such deposits will serve as a basis for discussion on the subject. In Canada, the most valuable of our placers are deposits of gold, and consequently the discussion will centre largely on placer-gold deposits. The same principles apply, of course, to placer deposits of other metals. The Origin of Placer Deposits As a starting point, the idea which is prevailingly held is that placer or alluvial gold is detrital in origin, that is to say, the gold originally existed in veins, lodes, or disseminations in the country rock of the regions in which the placer deposits are now found, and that, through the various erosive forces of nature, it was liberated from those veins or lodes and concentrated in the form in which we now find it. 1 have not time to go thoroughly into the proof of this, but the lines of evidence are many. If we take the Cariboo district as a typical example, Johnston and Uglow(l) have shown, first of all, that the placer and vein gold are identical in character. Crystals occur both in the placers and in the lodes, but the crystals in the placers are nearly always slightly worn, indicating transportation.

Jan 1, 1932

By R. D. Brown

Ever since British Columbia started the ball rolling in 1974 with the introduction of its now-defunct Mineral Royalties Act, all Canada's resource-based provinces have significantly altered their mining tax systems. The last resource-based province to abandon its pre -1974 mining tax structure is New Brunswick, which introduced a new mining tax regime in the summer of 1977 to take effect from April 1 1977. The new structure, which represents the outcome of considerable study and discussions with industry representatives, contains some intriguing concepts which make Nero Brunswick's new mining tax system unique among the Canadian provinces.

Jan 1, 1977

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 Philippe Caudal

This paper presents a case study in which a slope failure was observed on the west wall of the LAB Chrysotile mine in the vicinity of the main ramp in January 2010. Airborne LiDAR results were used to evaluate slope geometry before and after the failure occurred. Back analysis of the failure was performed to assess rock mass properties at the slope scale using various numerical techniques: limit equilibrium, finite elements and fracture networks. The various approaches correlated well with field observations.

Aug 1, 2013

By Rolf Andreas Lauten, Yanhong Wang, Yongjun Peng

"In mineral flotation, bentonite as a kind of clay mineral imposes deleterious effects on the flotation of valuable minerals, possibly through its ability to increase the pulp viscosity. A higher viscosity lowers the amount of froth and affects the bubble-particle collision frequency. A previous study found that adding gypsum to a bentonite-ore mixture lowered the viscosity, possibly by inhibiting the formation of interconnected network structures. In this study, sulfate as an anion with different types of cations, Na+, K+, Mg2+ and Ca2+ were used to reduce bentonite viscosity and to improve flotation performance. It was found that at the same concentration, MgSO4 was the most effective salt in reducing bentonite suspension viscosity, while CaSO4 was not as effective likely due to the lower solubility of CaSO4. Na2SO4 and K2SO4 reduced bentonite suspension viscosity at high concentration. Flotation kinetics of ore blended with bentonite was increased with increasing the electrolytes concentration, which generally correlated with the reduction of bentonite viscosity. Meanwhile, significant discrepancies were found between flotation results and rheological measurements in the presence of monovalent ions. It is indicated that the morphology of bentonite aggregates in electrolytes solution is likely to influence the hydrodynamics in the froth zone.INTRODUCTIONClay is present in many ore bodies as a gangue mineral. Presence of clay presents several challenges in the processing of valuable minerals. They are soft compared to valuable minerals, which means that during grinding of the ore, clay particles are likely to obtain a smaller particle size than the valuable mineral. Often clay particles may be within the colloidal size domain (<20 µm). The smaller size increases the probability of entrainment in the concentrate. Another challenge is their anisotropic charge distribution, where depending upon the pH, edges (E) and faces (F) carry charges of opposite sign. This facilitates formation of aggregation structures that may impede percolation of bubbles through a froth, but also increase the viscosity more than expected from the mere change in volume fraction. In addition to lowering the froth mobility, a high slurry viscosity will have implications for the gas dispersion in the flotation column as it affects the dispersion of the suspended particles, and it modifies the bubble-particle collision rate and attachment efficiency (Bakker, Meyer, & Deglon, 2009; Shabalala, Harris, Leal Filho, & Deglon, 2011). A pragmatic approach to this problem is to blend high clay ore with ore of lower clay content, reducing the overall clay concentration. Alternatively, one may lower the solids content of the flotation slurry to counteract the viscosity-building properties of clay. While feasible, this approach has the disadvantage of increasing required flotation volume, and it also affects the properties of the froth. Thus, there are currently limited options in lowering the impact of clays and their tendencies to increase viscosity in flotation slurries."

Jan 1, 2016

By Z. S. Shao, X. Z. Li

"Sub-critical crack growth plays an important role in long-term creep failure in brittle rock. Based on micromechanics established by using relationship between micromechanical wing crack growth model and macroscopic strain, and comparing theoretical model with testing results, a method, which applies the theory to real rock, is suggested in this paper. Using this method, properties of creep, damage and progressive failure in brittle rock are investigated. Effects of stress state on creep failure time and steady-state creep rate are analyzed and graphically presented. The results are helpful to support structure design and service life evaluation of underground structures with high geostatic stresses. INTRODUCTIONDuring the long-term operation in underground space with brittle surrounding rock, due to chemical action between pore water and rock, the failure of rock often occurs at stresses below its short-term failure strength, which brings serious effect on the long-term stability of underground structure. Thus, the long-term strength of brittle rock attracted wide interests of scholars around the world. The static fatigue limit was predicted by exponential function that is derived from abundant experiment data of stress level and failure time(Schmidtke & Lajtai, 1985), and similar result by relationship between stress state and failure time was also suggested (Lau & Chandler, 2004; Aubertin et al., 2000; Sangha & Dhir, 1972). According to relationship between steady creep rate and stress state during creep, a critical stress that transforms steady-state creep to accelerated creep was studied and the long-term strength was suggested (Tsai et al., 2008; Ma & Daemen, 2006; Lajtai et al., 1991). Based on the results of experiment in compression, the long-term strength of rock was defined by stress at volume strain reversal. When applied stresses are larger than the long-term strength, the microcracks in the rock will grow constantly, damage of rock will increase and failure of rock will occur finally (Chandler, 2013; Bieniawski, 1967; Brace et al., 1966)."

Jan 1, 2015

By F. M. Clement

British Columbia, unlike the Prairie Provinces, cannot lay claim to vast prairies. She can, however, claim many valleys, uplands and plateaus that are capable of marked agricultural development. It has been said that British Columbia is not an agricultural province. This may or may not be true, but at the present time agricultural production in this province stands second only to that of forestry. The industry has advanced from a total production of 8 millions in 1908 to a total production of 60 millions in 1924, a total increase of approximately 650 per cent in 16 years. In the last 10 years production has increased from 30 millions to 60 millions. No other industry can point to such a rapid development. In 1908 British Columbia imported 12 million dollars worth of foods compared to the 8 millions which were produced at home. In 1924 she imported 20 million dollars worth of foods compared to the 60 millions worth produced at home. In addition we exported foods to the value of approximately 10 million dollars. British Columbia is therefore self-sufficing in-so-far as values ar.e concerned except for approximately 10 millions of dollars. It is not to be expected that this province will ever grow all the coarse grains that she may require: these, along with certain meats, will always be a heavy item in the imports. We are concerned at the present time more with the value of the products than with the quantities produced: in other words, with quantities only in-so-far as ? quantities improve value.

Jan 1, 1925

By J. M. Harrison

FIELD PARTIES of the Geological Survey of Canada have, in recent years, mapped several areas east and northeast of Flin Flon (9, 10, 12, 13, 14, 15, 118) (1). In all these areas the mineral deposits show a close geographical relation to faults although the immediate control of most of the known ore deposits appears to be folded structures in the rocks (8, 11, 18, 19). Air photographs and published geological maps were studied in order to ascertain whether or not the mineral deposits in the Flin Flon-Snow Lake mineral belt as a whole show any spatial relationship to faults. It was found that most of them do show a distinct geographical association with faults, or with topographic features that may be faults. It is further apparent on air photographs that a major lineament, for composite of lineaments, follows approximately the contact between gneisses and schists of the Kisseynew complex on the north, and Amisk volcanic rocks on the south. However, this Kisseynew lineament is not continuous and, especially in the eastern half of the district, it is exceedingly irregular in plan. Parts of this lineament have been mapped as faults (9, 10, 12, 14), other parts have been shown as stratigraphic contacts (1, 2, 21, 27), and still other parts have not been studied except by reconnaissance methods. It is suggested that the Kisseynew lineament may be due to a deformed fault that extends easterly from a point about 25 miles west-northwest of Flin Flon to a point at least 10 miles northeast of Wekusko lake and that the mineral deposits.

Jan 1, 1951

By S. Jordanov

The nature of processes that take place on top of copper bearing grains during the suppression of copper acid drainage from mine tailings was studied on a grain model. Cyclic voltammetry (C.V.) was employed as an experimental technique suitable for indirect measuring of copper leaching. Experiments were done in sulfuric acid (pH=2) at electrodes that progressively approach the real situation during acid main drainage, starting with Cu-metal, then with CuO and finally with CuO covered with CaSO4. Oxidation was found to be the only process that takes place on metallic copper electrode anodically polarized up to 2 V vs. Cu/CuSO4 reference electrode. Dissolution is intensive and reaches up to 50 mA.cm-2. When the same was repeated, but on CuO electrode, anodic currents were some 4 times lower than on the bare metallic surface. This indicates that the electrode material is not completely oxidized to copper(II)oxide and the Cu(O) or Cu(I) residues are oxidized during the anodic polarization. This explains the diminished dissolution. Dissolution is further restricted at electrodes covered with CaSO4. It is some 20 times lower than on the bare oxide electrode. When the second layer of CaSO4 was applied, anodic currents were another 15 times lower. Total decrease of anodic currents when transition is made from Cu-metal to CuO covered with 2 layers of CaSO4 reaches up to 7.500 times. C.V. measurements produced a proof that mechanical blockage is the way how lime prevents leaching of copper bearing grains in immobilization experiments referred elsewhere.

Jan 1, 2007

By J. Gotor, C. Frias, E. Delgado

The Iberian Pyrite Belt (IPB) is one of the world&apos;s largest reserves of primary sulphides containing base metals (Cu, Zn, Pb), precious metals and some special metals such as indium. Estimated resources are over 1,500 million tonnes of volcanogenic massive sulphide ores. From 1980´s Europe lives the decline in its mines mainly motivated by the low price of the metals. One aspect that contributed equally to this was the ecological disaster produced by the discharge of more than seven million tonnes from the tailings dam of Boliden-Apirsa (Aznalcollar) in 1998. Today the situation is different; the companies present in the IPB have given evidence that it is possible to reconcile mining projects and care on the environment, and the regional authorities are opening a public tender to re-start Aznalcollar mine. A new challenging era has been started at this Spanish/Portuguese mining area. This paper presents the results and preliminary economics of a project devoted to IPB primary sulphides processing through different technology approach, e.g. conventional selective flotation against bulk flotation or mixed metals flotation combined with hydrometallurgical processing.

Jan 1, 2014