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By Robert B. Parsons

"As the 1981 annual reports of Canadian mining companies one by one see the light of day, it becomes clear that softer metal prices and rising costs are the main problems which beset the industry today. These problems are certainly not lightened by that familiar monster lurking in the shadows-taxation! Recent taxation trends in Canada, and the existing tax regimes for the mining industry, continue to be a major bugaboo.This examination by ""Tax Notes"" of the impact of current taxation trends on the mining industry is based on a speech delivered recently by Robert D. Brown, senior tax partner of Price Waterhouse, Canada, to the annual meeting of the American Institute of Mining, Metallurgical and Petroleum Engineers in Dallas.IntroductionThe purpose of this paper is to tell a story-and it is a story with a moral. The first thing to recognize is that, with depressed metal prices and weakening western economies, high taxes, in and of themselves, are not really the cause of the Canadian mining industry's present doldrums. However, the character and level of mining taxes in Canada has had a profound influence on the development of the industry over the past decade, and the expectations of what the future holds for mining men in Canada will equally play an important role in the future development of the Canadian industry. Our tax system has, in the past, served as a negative and destabilizing influence in the mining industry: it has contributed to a major short-fall in investment commitments and hence in the contribution which the mining industry can make to the Canadian economy, and the adverse effect on the industry of previous high marginal tax rates was made far worse by the confusing, contradictory and perverse nature of the tax system itself."

Jan 1, 1982

By B. Drew, K. Budna, C. Wenzl, D. Gregurek, A. Spanring

"The metallurgy of nickel and cobalt and of copper is closely interlinked when processing sulfidic Ni-Co ores and Cu-Co ores. The respective furnaces are typically lined with magnesia-chromite refractories, which are exposed to multiple and complex stresses. The selection of the processing route, furnace type and slag system will be dictated by the specific ore type available, this will determine the individual refractory wear mode. This paper evaluates the common refractory wear mechanisms, namely infiltration, spalling and chemical attack by various slag systems, as well as sulfur attack, as observed when processing primary sulfidic ores. All these wear parameters, which are discussed in this paper, lead to a severe degeneration of the brick microstructure and a decreased lining life. Therefore, a detailed investigation and understanding of the wear mechanisms through “post mortem studies” is an important prerequisite for the refractory producer. Based on such research results, combined with specific process knowledge, appropriate brick lining solutions for nickel and cobalt processing furnaces can be recommended.INTRODUCTION The metallurgical production of cobalt and nickel and of copper is closely interlinked to the mineralogy of the respective ores: cobalt is found in African Cu-Co ores as well as in Co-rich nickel ores (laterites and sulfides). Also, Co-bearing secondary raw materials contain the mentioned elements in different contents. In pyrometallurgical processing of sulfidic ores, cobalt is generally recovered as a by-product during the production of copper and nickel, whereas it is normally not recovered separately during the processing of nickel laterites but remains in the FeNi product. Besides various hydrometallurgical production routes, the pyrometallurgical processes involved comprise smelting (i.e., production of a Cu-Ni-Co-Fe matte in electric or flash furnaces), converting and refining (i.e. removal of Fe and S as well as other elements from matte by oxidation). The ongoing trend to use higher oxygen enrichment in process air enables higher intensity processes but also increases the oxidation potential in the vessel. Therefore, during smelting and especially during the oxidative treatment in converting and refining, some amounts of valuable metals are also transferred to the slag in their oxides form. A subsequent slag treatment is then applied for recovering valuable metals from the slag, namely allowing an economic material stream handling and minimizing metal losses. This is often done in a slag reduction furnace. Additionally, copper and nickel are very good collectors for precious metals and platinum group metals (PGMs) - therefore, depending on the content of these metals, an additional refining process is used to recover these valuable metals from the matte or metal phase (Elvers et al., 1997; Davenport et al., 2002; Crundwell et al., 2011)."

Jan 1, 2017

By Gordon. I. M., J. Blackshaw

"The wet part of the Hollinger mill is housed in two buildings, the grinding plant and the treatment plant. In the grinding plant there are four 7xl5 ball mills which grind the ore to 60 per cent through 200 mesh. There is also one 7xl5 ball mill which grinds table concentrate to 9 5 per cent through 200 mesh.The primary classifier overflow is pumped to the treatment plant where it passes over shaking tables, producing a concentrate and a tail. The concentrate pulp is pumped to the grinding plant for secondary grinding. The secondary classifier overflow is pumped back to the treatment plant where it is thickened in two 40xl 5 tray thickeners and agitated in four 20x24 mechanical agitators arranged in series of two (with 2 spares).The table tail pulp is thickened in nine primary 40xl5 tray thickeners (with 2 spares). The thickened table tail pulp and the concentrate agitator discharge pulp are mixed and pumped to four rows of 15x45 pachuca agitators, arranged in series of five tanks.The pachuca discharge pulp is divided. The smaller part goes to two rows of 3-step decantation using 40xl5 tray thickeners (with 2 spare rows). The larger part goes to six 14xl6 drum filters. The repulped primary filter cake and the thickened pulp discharged from the decantation rows are fed to eight 14xl6 drum filters. The secondary filter cake is mixed with water and pumped to the tailing line."

Jan 1, 1968

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

The 1973 Oil Embargo and succeeding disruptions in supply had a profound effect on energy costs and consumption patterns in the developed world. This was especially true in the USA where post World War II growth, fueled by low-cost imported oil, left the country dependent on uninterrupted oil shipments from the volatile Middle East. In this atmosphere, Professor H.H. Kellogg of Columbia University, convinced of the necessity of good environmental stewardship by the writings of the era’s leading environmentalists, developed a methodology for evaluating energy and process efficiency of metallurgical processes and wrote a series of papers describing and applying the techniques. One of these, "Energy Use in Sulfide Smelting of Copper" is recognized as a seminal work which both described the state of energy usage in copper smelting in the mid-1970’s and portended future developments. The background to these papers is examined and the current and past Cu-Ni matte smelting practices in Canada are examined in the context of the results. Data from early 20th century publications describing reverberatory and blast furnace operation is employed to show that energy consumption for much of the century was several multiples higher than that calculated for best reverberatory operation in the 1970’s.

Jan 1, 2015

By K. E. Waters, C. Marion, T. Grammatikopoulos, A. Jordens

"The Nechalacho deposit, located in the Northwest Territories, Canada, is a heavy rare earth element (REE) deposit. The main REE-bearing minerals in the deposit are zircon, allanite, bastnäsite, synchysite, columbite (Fe) and fergusonite. Previous work investigated the use of gravity and magnetic separation in the processing of this ore and showed that coarse particles following grinding were enriched in zircon, suggesting the potential for selective comminution. The current work investigates the possibility to selectively comminute gangue minerals and concentrate REE-bearing zircon into coarser size fractions. The ore was ground wet in a laboratory rod mill for various lengths of time (0, 10, 20, 30, and 40 min). The resultant products were analyzed using ICP-MS, to determine the distribution of zirconium and REEs in the different size fractions produced after grinding, and QEMSCAN, to identify mineral phases, mineral liberation and the distribution of minerals. Optimum grind sizes for the upgrading of zircon due to selective comminution were then proposed, and dense medium separation was investigated as a means to further concentrate zircon.It is important to note that this process is not representative of the currently selected process design or recovery for the Nechalacho deposit. Any application of this process to this deposit would require optimization in order to ensure appropriate grade and recovery targets are met.INTRODUCTIONThe rare earth elements (REEs) are the fifteen elements in the lanthanide series of the Periodic Table, as well as yttrium (scandium is excluded in this work). Traditionally, REEs are categorized into two groups: the cerium sub-group of “light” rare earth elements (LREEs); and the yttrium sub-group of “heavy” rare earth elements (HREEs) (Golev et al., 2014). The LREEs comprise the first six lanthanides (lanthanum through samarium) and the HREEs comprise the remaining nine lanthanide elements (europium through lutetium) coupled with yttrium (Golev et al., 2014). HREEs are much less abundant in the earth’s crust and on average are more expensive than LREEs (Seredin, 2010). Of the fifteen REEs, the production of neodymium, europium, terbium, dysprosium and yttrium has been determined to be most critical due to their scarcity, high demand and criticality in many high-technology and clean energy applications, such as in illuminated screens for electronic devices and permanent magnets in wind turbines (Seredin, 2010; U.S. Department of Energy, 2011). These five elements are classified as critical rare earth elements (CREEs) (U.S. Department of Energy, 2011)."

Jan 1, 2016

By H. O. Olsen

"GeneralTHE IRON ORE at Marmora is a replacement deposit of Precambrian limestone and is overlain with Palaeozoic limestone. It is a low-grade magnetite deposit and the ore will require concentration be-fore it can be used economically for the production of iron and steel.Present plans estimate an annual production of 500,000 tons of concentrate in the form of pellets. This will require mining approximately two million tons of ore and\ waste annually. Shipment of pellets from Marmora to a ship-loading dock at Picton will be made by rail on a year-'round basis. Shipments from Picton to the Lackawanna plant of the Bethlehem Steel Company at Buffalo, N.Y., will be carried on during the Lake shipping season.LocationThe mine, located a mile southeast of Marmora village in Hastings county, Ontario, is 31 miles north of Belleville and 3•7 miles east of Peterborough. Marmora is 130 miles from Toronto and 150 miles from Ottawa. Highway No. 7 passes half a mile north of the mine and Highway No. 14 half a mile west of the mine. The Canadian National railways' branch line between Trenton and Bancroft passes through the property just east of the open pit.HistoryThe Ontario Department of Mines conducted an airborne magnetic survey of the district during 1948 and 1949. Maps of this survey were released to the public early in 1950. Bethlehem representatives carried out ground surveys in the Marmora area shortly thereafter and in June, 1950, commenced diamond drilling."

Jan 1, 1955

By M. H. Govett, G. J. S. Govett

"The current American ""energy crisis"", occurring in the midst of a global debate on the adequacy of mineral supplies to support present and projected levels of world consumption, has focused attention on Canada as a major world producer of minerals. Exports of minerals account for approximately one-third of Canadian foreign earnings; more than half of these exports are to the United States. Although the United States is a net importer of most industrially important metals, with the exception of nickel and zinc, only a small part of American mineral imports are from Canada; these imports are minerals for which geographical proximity and strategic considerations are important. In the short-term, Canada is more dependent on her exports to the U.S. than America is on imports from Canada. It is argued that Canada, far from indulging in economic nationalism to preserve her resources, should expand her exports while the markets are available."

Jan 1, 1973

By L. Narhi, K. Haavanlammi

"Approximately two thirds of annual nickel production is used as a raw material in the making of stainless steel, and about 60% of these nickel products are in the form of metallic nickel such as nickel cathode or briquettes. In the stainless-steel production process nickel is blended with iron and chrome-based raw materials, and metallic nickel is typically only required for final steel fine-tuning. Outotec offers a new FeCrNi technology to enhance the nickel value chain for stainless steel producers. This involves the use of an HPAL-based intermediate nickel product (e.g., mixed hydroxides or NiO) as raw material in the Outotec FeCrNi process, for the production of a FeCrNi Master Alloy. The new process, designated as the FeCrNi process, offers multiple benefits compared to existing technologies such as: higher tolerance for impurities in the HPAL intermediate product, avoiding the need for further nickel refining, and the improved recovery of all metals in the FeCr process. The complete new FeCrNi value chain is based on proven technologies such as HPAL and the Outotec FeCr-process. This new innovative and promising value chain offers improved efficiencies for the HPAL based nickel production process combined with excellent sustainability aspects.INTRODUCTION In today’s global economy there is a constant need to improve the efficiency and sustainability of the metals production. The requirements for modern metal refining are tightening and cost efficient, safe and sustainable operation is the precondition for all investment. Outotec is offering now a novel way to combine FeCr and Nickel production to create a completely new value chain to source nickel to stainless steel. BACKGROUND Nickel The current nickel mine production is in the level of 2,000 tons annually and it is split 44% from sulphide based deposits and 56% from laterite deposits (Figure 1). Most (40%) of the nickel is refined to pure nickel metal whereas other products are FeNi (19%) and Nickel Pig Iron NPI (20%) (Roskill). The remaining part, roughly 21%, is nickel chemicals and intermediates. Most of the new investments in nickel are in the direct shipping of laterite to produce nickel pig iron. HPAL process is considered in few projects but no major HPAL projects have been started since the Ambatovy plant in Madagascar. Ambatovy reached the commercial production in 2014. The main primary nickel used is stainless steel manufacturing. In the year 2016 about 68% (~1,360 kt) of primary nickel production was used in stainless steel."

Jan 1, 2017

By M. Epiney, A. Ghahreman, R. Kim1and

"In the presence of sulfidic refractory ores, increasing the dissolved oxygen (DO) concentration can positively affect the gold leaching rate. To identify the role of DO in gold cyanidation, electrochemical behavior was studied in the presence of 3 different ores. Sample 1 was a low sulfide pyrite ore, contained 5.14% pyrite, 0.19% galena and 3.09% S. Sample 2 was a pyriticore as well, contained more sulfide as 8.35% S, and 12.4% of pyrite. Sample 3 was a tailing of silicate gold ore, still containing75 g/tAu, 0.13% Pb and 0.18% S. Gold cyanidation kinetics were studied by cyclic voltammetry (CV) and chronoamperometry tests. With sample 1, the gold oxidation peak current density from CV curve was increased to 1.38mA/cm2under oxygen injection, while it was only 0.66 mA/cm2with air injection. From chronoamperometry test, the reaction rate was also faster under oxygen injection. Sample 2 showed similar behavior with sample 1, but the gold oxidation peaks higher than sample 1, i.e. 1.75 and 2.27 mA/cm2, under air and oxygen injection, respectively. However, it seemed that the gold oxidation was impeded by sulfide ions for a longer period. In the presence of sample 3, the gold oxidation peak was the highest among three ores –2.75mA/cm2under oxygen injection, because of its lowest sulfide content. However, from chronoamperometry test, it was also shown that the gold oxidation was impeded because of a significant amount of Pb in the ore sample.INTRODUCTIONIt is well known that gold is leached under oxidative condition (Marsden &House, 2006). Through the most representative and oldest gold leaching technique, cyanidation, more than 90% of gold can be selectively leached from an ore. According to Elsner’s equation, gold is leached in cyanide solution by forming cyanide complex [Au (CN)2–], and oxygen is consumed as an oxidant(Eq. 1)."

Jan 1, 2017

By T. Richard Davies

This paper primarily deals with the application of wearfacing materials and their role within a well-established preventive maintenance welding program. Some examples are shown, as well as a synopsis of possible benefits and a compendium of methods and materials.

Jan 1, 1979

By J. Currie, J. McManus, R. Chenier

"Cominco Copper Division's Valley Mine is located in the Highland Valley of British Columbia, approximately 275 km by air northeast of Vancouver. The nearest towns are Logan Lake, located IS km to the east and Ashcroft, located about 50 km to the northwest.Preproduction stripping of rock and overburden at the Valley Mine's Lake Zone Pit began in mid-1982 following a decision to discontinue mining in the adjacent Jersey Pit. Equipment and mining methods were carried over from the Bethlehem Copper operations which, with Valley Copper Mines, were merged into Cominco in December 1982.Blasting practices, as carried over from the Bethlehem pits, were designed to provide the fine fragmentation required to meet production requirements using the Bethlehem crusher. However, after mining the first few benches of the Lake Zone Pit, it became apparent that overblasting at the pit limits was causing a number of bench failures, as well as contributing to an over-all reduction of the material strength of the rock mass forming the southwest wall of the pit.With present ultimate pit plans calling for the southwest wall to be as high as 300 m, Valley staff realized that potential slope stability problems should be dealt with as early as possible. This philosophy would enable experimentation on phase pit walls in order to attain the optimum slope angle on the ultimate pit wall.As part of an over-a ll slope stability program, a controlled blasting program was initiated at the Lake Zone Pit in March 1983. In this program, Valley engineering and production staff worked together with Golder Associates in establishing design criteria and evaluating the results. This program resulted in a marked improvement in the soundness of pit walls while maintaining the required degree of fragmentation."

Jan 1, 1985

By Jin-Hwa Song

Rolling temperatures and cross rolling ratios were varied to investigate the effect of crystallographic texture of alpha-phase on the anisotropy of mechanical properties in modified Ti-6A1-4V alloy. Hot rolling method was unidirectional and cross rolling, during which the rolling temperature was in the range of 830°C and 920°C. Cross rolling ratios were varied from 0.3 to 1.0 at 875°C. For unidirectional rolling, as the rolling temperature increased texture changed from the mixed basal and transverse texture to the simple transverse texture. Contrary to other work, it was observed that the maximum intensity of transverse components increased with the increase in rolling temperature. For cross rolling, on the other hand, the transverse texture component was almost suppressed at 830°C, giving rise to a symmetrical basal texture. With increasing cross rolling temperature, the transverse texture components developed again. A simple transverse texture, which showed two maxima appearing circularly 90° apart, was observed at 920°C. It was found that unidirectional rolling could not eliminate the transverse texture, which resulted in the anisotropy of mechanical properties. The anisotropy of mechanical properties obtained from tensile and V-notch Charpy test was closely related to the crystallographic texture and its intensity at each rolling condition. To obtain the isotropy of mechanical properties by cross rolling, it is suggested that cross-rolling ratios should be controlled above 0.5. The variation of rolling temperatures and directions has great influence on the anisotropy of impact value rather than tensile strength.

Jan 1, 2004

By G. Itoh, S. Fukasawa

The Al-Zn-Mg alloys have been known to be susceptible to stress corrosion cracking (SCC), which is based on intergranular cracking arisen from hydrogen embrittlement (HE). The mechanism of HE has not been fully understood yet. In order to elucidate the mechanism of HE, we need to investigate the behavior of hydrogen in the alloys. In this paper, behavior of hydrogen in an Al-5.8%Zn-2.4Mg alloy was investigated by means of hydrogen microprint technique, a method to visualize location of hydrogen emission from specimen surface as silver particles. One side of the tensile test pieces was electrolytically polished and then covered with photographic emulsion. Hydrogen was pre-introduced into the test pieces from opposite side by cathodic electrolytic charging for 30min. Then, the test pieces were stretched with continuing the charging. After that, the specimen was fixed, rinsed, dried and observed with a scanning electron microscope. As a result, silver particles were observed on some grain boundaries.

Jan 1, 2015

The paper will cover the basic reasons for alkaline leaching, a brief description of the circuit and the reasons for the flowsheet used. Changes made to the flowsheet, including the use of mechanical agitation of pachuca slurry, the use of oxygen and its effect on extraction, the use of lime and its effect on process economy, and the environment, will be described. A brief description of a unique semi-autogenous mill and future circuit changes will be included.

Jan 1, 1979

By Sina Mostaghel, M. Guo, E. Klaffenbach

The current paper is focused on evaluating the behavior of copper in a copper production slag and the assessment of metal recovery possibilities. For this reason, thermodynamic calculations were carried out to determine the influence of parameters such as slag composition, temperature and oxygen partial pressure on recovery of non-ferrous elements. It was found that the formation of a solid face centered cubic (fcc) phase, mainly consisting of iron, limits the extent of reduction that can be achieved for an industrial process. However, it could be discovered that solubility of iron in the Cu-rich liquid alloy strongly depends on presence of other elements, particularly arsenic. As part of the results of this study, the solubility of Cu in the slag at onset of fcc phase formation is presented as function of temperature, oxygen partial pressure and concentration of MgO and CaO. It was concluded that lower temperature (1200°C) and higher CaO addition (16 mass-% in this study), would result in the highest achievable copper recovery from slag. INTRODUCTION Copper slag is produced as a by-product of the copper production process. The slag is still containing a high amount of copper and other valuable metals. This demands further treatment of the slag as a secondary source of metals. In addition, the physical/mechanical properties of slag allow its use in several applications such as hydraulic engineering, civil engineering, as an abrasive and many more. These applications help reducing the use of natural resources like rock and sand. By decreasing the content of heavy metals such as Cu, Pb, Zn and As in the slag, its application in abovementioned fields becomes more attractive as the probability of releasing these elements to the environment is further reduced. To develop a pyrometallurgical slag reduction process, it is necessary to understand what describes the end point of the reduction. This point is expected at maximum copper recovery without facing operational challenges. Existing literature provide some information on the effect of different parameters such as temperature or concentration of different slag formers, on solubility of copper and heavy metals in different phases. However, due to complexity of industrial slags, equilibrium experiments and accurate thermodynamic modelling are essential to be able to reliably predict the behavior of different elements in the system and determine the end-point of reduction.

Jan 1, 2019

By M. S. Diederichs, J. Oke

Surface limitations and a need for more direct transportation routes require serious consideration be given to the development of underground construction works in geotechnically unfavourable conditions. Due to geographical and logistical limitations, the construction of these underground works is restricted to difficult ground conditions that require temporary pre-support before excavation in order to avoid tunnel collapse or severe surface settlement. One type of pre-support is the umbrella arch system, which has been gaining popularity due to cost and time commitment in comparison with other pre-support systems (e.g., ground freezing). The umbrella arch system has been employed with significant frequency around the world, yet without a complete understanding about the mechanical response of the system. As such, literature has found the temporary support system to be both under and over designed with regard to safety and/or economical impact. The authors of this paper have made three major contributions to increase understanding of the umbrella arch system and to help optimize the design process. Firstly, the authors have developed nomenclature in order to categorize and define umbrella arch elements and systems, which also stimulated the creation of the empirically driven Umbrella Arch Selection Chart. Secondly, the authors have established a design methodology that is primarily based on advanced numerical modelling techniques to aid in the optimized design of the umbrella arch arrangement for site specific conditions. Thirdly, the authors have developed a semi-analytical model for umbrella arch systems employed in squeezing ground conditions by incorporating elastic foundation theory as well as convergence confinement theory. These three major contributions to such a widely employed tunnelling pre-support system will be introduced and explained in detail, and will include discussion of how each is incorporated in the complete tunnel support design process and throughout the construction and monitoring phase of a project.

Jan 1, 2015

By E. Stansfield

Coal samples are sometimes taken from a wet spot in a mine, or from an open car or pile shortly after rain, and submitted for analysis in a dripping wet condition. Other samples are taken from a dry spot in the mine, or from an open car or pile after a period of dry weather. Comparison of the analyses obtained in the two cases would be absurd, although the samples might be of essentially the same coat apart from the surface moisture on the one. The analyst therefore attempts to reduce all samples to an equal basis by the operation known as air-drying. Air-drying is practised by the chemist for three reasons: (1) To make it possible to grind the coal to powder. (2) To bring the coal sample to a condition in which it will not change in weight rapidly whilst portions are being weighed out for analysis -in other words, to bring it into equilibrium with the air in the laboratory. (3) To determine the water-retaining power of the coal. Any kind of drying is satisfactory for (1); the coal should be dried more or less according to the humidity at the time in the laboratory for (2); whilst it should be always dried to the same extent for (3). In other words, no method can be satisfactory for both (2) and (3). In this paper the only question considered is (3) -that is, air-drying the coal under standard conditions so that strictly comparable results can be obtained for the water content of coals after air-drying. After a sample of wet coal is exposed, it loses moisture until it is in equilibrium with the air at the time: thus the coal will loose distinctly more water in air of 20 per cent relative humidity, for example, than it would in air of 80 per cent.

Jan 1, 1923

By P. L. Wright

"This is a brief history of the development of the mining project, with a description of the proven geology. The paper describes how the experiences gained progressively demanded change in the mine design. The equipment used is described, together with methods of working. Interesting facts have been proved regarding gas emissions and roof. supi;iort. The. working cycles evolved are completely flexible m operation and lend themselves to maximum utilization of the most productive units. The two underground mines are compared, showing the variance in conditions already experienced. Programs currently in operation to improve standards and production are: the training of miners, maintenance men and officials; experiments in floor consolidation and continuing roof support trials; and the effect of comparative stability of working crews on the performance of the operation."

Jan 1, 1973

By R. N. W. DiLabio

"In a continuing program of mapping glacial dispersal trains, near-surface till samples were collected down-ice from a copper-silver-gold prospect at Onaman River, Ontario, and down-ice from the past-producing gold district at Oldham, Nova Scotia. The program is designed to aid exploration by illustrating glacial dispersal from various types of known occurrences and by identifying postglacial processes that control drift composition at a detailed scale.Native gold was mined at Oldham from arsenopyrite-bearing saddle reef quartz veins in a dome in Early Paleozoic slates of the Meguma Group. Gold abundances greater than 10 ppb in till form a dispersal train at least 1900 m long. Gold abundances between 40 and 100 ppb occur in clusters up to 600 m down-ice from gold-bearing bedrock. Anomalous arsenic abundances in till form a broad train 1100 m long that is significantly different in shape from the gold train.At Onaman River, subeconomic amounts of Cu-Ag-Au occur in quartz lenses in Archean mafic volcanic rocks. A dispersal train defined by the distribution of mineralized boulders and increased abundances of Cu, Ag and Zn in till extends 600 m down-ice from mineralized bedrock. Gold abundances between 10 and 70 ppb do not define this dispersal train, but occur instead in clusters 300 to 600 m down-ice from mineralized bedrock. In vertical sections in the upper 2 m of copper-rich till, Au abundances vary sympathetically with Ag and Cu levels; however, there seems to be no preferential site of Au enrichment in the mineral portion of the soil profile.Several of the mineralized boulders at Onaman River are richer in Au and Ag than the mineralized bedrock from which they were derived. Although some of the high Au and Ag assays were caused by biased sampling of sulphide-rich portions of the boulders, many were caused by leaching of sulphide minerals from 'the boulders, which left a limonitic boxwork that is enriched in Au and Ag. A few of the Au-rich boulders may have been derived from an unknown bedrock source."

Jan 1, 1982

To date, improved thickening of clay mineral dispersions presents major technological and environmental challenge to mining and mineral processing industry worldwide. Flocculant-assisted dewatering processes currently employed during thickening are far from being efficient, requiring further development and process optimisation for dramatic improvement. In this paper, recent studies carried out to modify (i) pulp chemistry, (ii) flocculation performance and (iii) particle interactions to significantly improve the dewatering behaviour of flocculated, model and plant smectite and kaolinite clay dispersions are presented. It is shown that pulp pH-mediated hydrolyzable metal ion hydrolysis and specific adsorption in tandem with high molecular weight flocculant and shear may synergistically act to significantly enhance the dewaterability of both clay mineral pulps. Furthermore, polymeric flocculant structure type is demonstrated to show clear links with floc shear sensitivity, and hence, flocculation performance and pulp dewaterability. The implications and relevance of the findings plant clay mineral waste tailings thickening operations are drawn.

Jan 1, 2006