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By BARRY BANNATYNE

Ombrotrophic Sphagnum peat bogs have a characteristic signature on both colour injrared film (750 nm to 3,000 nm response) and Daedalus injrared line-scanner images (thermal infrared 3 to 5 microns and 8 to 14 microns response). This remote sensing method was used to survey bogs in southeast Manitoba to delineate targets for surface exploration. Target bogs all have a surface growth of Sphagnum; underlying dead Sphagnum ranges from 1 to 6 m thick. Large Sphagnum reserves exist in the Caribou cluster of bogs, and in /979 a bog first identified by infrared sensing was brought into production.

Jan 1, 1984

By M. G. Rylatt, G. M. Popplewell

"Production from Canada's first diamond mine is planned for the last quarter of 1998. The climatic conditions and the variation in kimberlite types to be treated have lead to the development of a compact and flexible processing plant.High kimberlite moisture contents and winter temperatures below -40°C have dictated a process flowsheet with limited in-circuit storage to reduce materials handling difficulties. The latest developments in High Pressure Grinding Roll technology will be used to liberate the valuable diamond, reduce diamond breakage, and increase fines production to reduce the amount of material for down stream processing in the Heavy Medium Separation section.A varying heavy mineral concentrate yield has lead to the development of a final Recovery section that will incorporate Attrition Milling and Wet High Intensity Magnetic Separation for concentrate reduction. The latest developments in diamond X-ray sorting will be used to produce a final diamond concentrate for mechanical sizing, weighing and packing.Fine tailings thickening will utilise Deep Bed Compression type thickeners. This relatively new technology can produce;i) high underflow densities at low flocculant dosage rates, andii) clear overflowswith a smaller thickening area than conventional high-rate thickeners."

Jan 1, 1998

By Mory M. Ghomshei

"The cost of deep underground mine cooling depends on a number of geological, environmental and economic factors such as the temperature gradient in the mine, the outside air temperature, and the local price of energy. While geological factors, being static, can be controlled to some extent during the mine design, the environmental and economic factors dynamically change and therefore can only be controlled through a flexible mine ventilation system.With an average temperature gradient of 20–25°C/km, the virgin rock temperature at 2,000 m can reach 45–60°C. Conventional cooling at such depths could lead to exorbitantly high costs. In-mine geothermal heat pumps can considerably reduce the cost of cooling through energy communication with the centralized absorption chillers, which service the mine from the surface.It is shown that in-mine heat pump systems can be a viable option for reducing operating expenses and providing some degree of flexibility to cope with fluctuating energy costs. The price of Natural gas and electrify are the most important variables for optimizing the level of interaction between the surface and inmine cooling systems. Deep mine waters can be used to carry a portion of the mine heat to the surface, where the heat from mine can be used as a supplementary energy source for absorption chillers. As an extra benefit, the heat output of the chillers can be used for district heating and or greenhouse growing.The case of cooling deep levels of deep mines in Sudbury Canada (e.g. Creighton Mine) has been discussed. It is shown that an initial 1MW in-mine geothermal heat pump system can save significantly on the cost of cooling. Such a demonstration project will allow R&D on viability of larger similar systems to be incrementally added in the future.INTRODUCTIONThe amount of heat generated in deep and ultra-deep mines depend primarily on the regional temperature gradient and the thermal conductivity of mine rocks. The conductive heat flow is quantifiable and can be minimized or optimized in the process of mine design. Another important heat source can be related to underground equipment such as diesel machinery which often have low efficiencies (approximately 25–35%). This heat source can be controlled and reduced though improving efficiencies or using electrical equipment, which offer a much better efficiency (approximately 80–90%). Mine waters can also be a significant heat source (convectively bringing large amounts of heat into the mine workings)."

Jan 1, 2019

The Buzwagi Project is owned by Barrick Gold Corporation and located in the Lake Victoria Goldfields of central Tanzania in the District of Kahama in the Region of Shinyanga. The property is 6 km Southeast of the town of Kahama, 3 km South and adjacent to the road between Nzega and Burundi. The Buzwagi property is 97 km South of Barrick?s Bulyanhulu Mine. There is access to the rail line which connects from Isaka to the Indian Ocean coastal ports of Dares Salaam and Tanga. The Feasibility Study and permitting were started in early 2006. Project Execution commenced in August 2007. Process Plant commissioning started in January 2009 and the first gold pour is scheduled for Q2 2009. The reserve has been established as 3.3M oz of gold plus 177M lbs of copper. The project has been developed to include a 30Mtpa Open Pit Mine and 4.4 Mtpa Process Plant. Over an expected 15 year mine life, Buzwagi is anticipated to produce approximately 3.02M oz of gold and 220,000 tonnes of copper concentrate. Infrastructure associated with the project includes a 107 km 220kV power line, site accommodation, water harvest and extensive security facilities. The project is expected to be built on budget and on time during a period of extreme market volatility. This paper reviews the initiatives taken to achieve community support, control cost escalation, maintain schedule and manage logistic challenges, plus ensure security and safety of all workers.

May 1, 2009

By W. B. Boggs

This is a rather comprehensive subject and cannot be thoroughly covered in the short rime allowed for its presentation. This article will touch only upon a few of the chief points of the difficulties encountered in recovering copper from brass shell cases in a primary smelter which was not designed to treat scrap metals. Owing to the fact that the plant is at present (Dec., 1946) closed, and our tests were not completed, full details of the results are not available. As is well known, most primary smelters are situated near the mines in the interior of various countries and are not close to seaports or large industrial and railway centres. Consequently, iris unusual for a primary smelter to be asked to treat scrap metal of any kind. When so required, iris obvious that the primary smelter is at a great disadvantage, for the simple reason that it probably has to pay the freight on the scrap from the seaport or industrial centre to the smelter and then also pay the freight on the recoverable metal from the smelter to the refinery, or seaport or industrial centre. Another disadvantage is that a primary smelter is not equipped to sample and unload the scrap nor bas it usually the equipment adaptable for treating the scrap efficiently, as the plant bas been designed to handle large tonnages of ores and concentrates. This short paper will describe some of our difficulties> and how they were corrected. However, it might be advisable to state briefly some of the methods used in treating brass shell cases in other plants. In the first place, a brass plant producing new brass- especially those producing brass billets for extrusion to make brass tubes or rods, or to be drawn into wire, or making brass cake to roll into brass sheets- generally insists upon using new electrolytic copper and zinc and is opposed to using any scrap or secondary brass . Consequently, such a plant usually will not treat brass shell cases. Therefore, the usual procedure is to ship brass shell cases to a secondary smelter, where it is generally sorted, melted, fire-refined, and returned to the market in the form of a high or low brass ingot which can be sold to brass foundries for making brass castings. This evidently is the cheapest and simplest method. Another method is to ship to a smelter which is a combination of a primary and secondary smelter attached to or near an electrolytic refinery. In plants of both these types, that is a primary smelter with Cottrell dust collectors or a combined primary and secondary smelter with Cottrells or a bag house, the zinc may be wasted. However, if a bag house is used, some of the zinc is recovered, but it is usually contaminated with other metals and further processing is required to recover it.

Jan 1, 1947

By M. J. Dry, G. B. Harris

"This paper presents basic chemistry and operating conditions for the hydrolysis of ferric chloride into solid hematite and gaseous hydrogen chloride, and shows how this unit operation can be applied in chloride hydrometallurgy to regenerate strong hydrochloric acid and reject iron without also rejecting valuable metals such as nickel, copper and cobalt. Two examples are used to illustrate the hydrolysis technology and compare it to existing technology. The first is the regeneration of spent steel pickling acid, comparing hydrolysis to conventional pyrohydrolysis. The second example is the processing of a hypothetical low grade nickel laterite, comparing the novel chloride hydrolysis route to conventional sulphate HPAL technology.INTRODUCTION Whilst, in many respects, the control and removal of dissolved iron from chloride leach solutions can resemble the manner in which it is done in sulphate systems, chloride chemistry additionally offers the ability to achieve the same objectives in different ways (Harris, 2014). Conventionally, iron is oxidised to its ferric state (if necessary) and then precipitated with a base, usually magnesia where the feed is a laterite and lime where it is a sulphide, since calcium will precipitate sulphate formed during leaching. One method for controlling iron is to form FeOOH, either ß-FeOOH (akaganéite), a-FeOOH (goethite), or a mixture thereof (Fillipou and Choi, 2002). However, if akaganéite is formed, the precipitate will contain a significant chloride component (as high as 7% Cl), leading to chloride losses and difficulty in satisfactorily disposing of the residue. Washing chloride from akaganéite is almost impossible due to the propensity of the solids to undergo peptization. The conventional approach requires the addition of a base, but it is based to some extent on controlled supersaturation precipitation (Demopoulos, 2009), which produces a more uniform and crystalline material and is far more attractive than, for example, the turboaeration process proposed by Great Central Mines in their chloride copper process (Raudsepp & Beattie, 1986)."

Jan 1, 2016

By L. Beiza, L. Velásquez-Yévenes

Chalcopyrite is by far the most abundant copper sulphide on Earth, but it has proved to be problematic in its processing by leaching, mainly related to its refractory nature, slow kinetic rates of dissolution and the formation of an inhibiting product layer on its surface during leaching. This study is focussed on the electrochemistry of chalcopyrite dissolution in acidic chloride system, which has recently gained attention as a feasible alternative to conventional sulphate media for chalcopyrite leaching. It is well understood that chalcopyrite dissolution from mineral grains depends strongly on the solution redox potential at the mineral surface as well as the composition of the product layer that may form on its surface. The chloride ions in solution support the Cu(II)/Cu(I) couple as the primary oxidant, as they can form complexes with the cuprous ions formed, increasing the dissolution rate. Additionally, these ions increase the potential range where chalcopyrite can be oxidized. The chemical reaction that occurs on the surface of chalcopyrite in chloride solutions in the presence of cupric ions will be characterized and the coulometry of the reaction will be reported to understand what is happening on the surface of chalcopyrite. Electrochemical experiments have been carried out to investigate the behaviour of mixed potential by open circuit potential (OCP) measurement for 30 minutes using sulphuric acid at pH 1 under nitrogen at 25⁰ C. The effect of chloride was analysed at 0, 20, 50 and 100 g/L and cupric ions from 0 to 50 g/L. The potentials obtained were then used to carry out chronoamperometry tests for a period of 30 minutes in absence of cupric ions. The mixed potential did not show a significant difference with an increase in cupric concentrations in the absence of chloride. Increased mixed potentials and current densities were observed at higher chloride and cupric concentrations. Chronoamperometry tests at those potentials were used to construct a voltammogram trace which has the same trend as a normal cyclic voltammogram but with much lower current densities. INTRODUCTION As a result of the depletion of copper oxides, the leaching of copper sulphide minerals has become the focus of many studies. Chalcopyrite, (CuFeS2) which is the most abundant of copper minerals, has proved to be challenging to process via hydrometallurgy, mainly related to its refractory nature, slow kinetic rates of dissolution and the formation of an inhibiting product layer on its surface, during leaching.

Jan 1, 2019

By H. Ito, T. Takasu

A leaching process for recycling small car motor scraps dismantled from End- of - Life -Vehicles (ELV) was investigated using waste pickling acid in steel work. Steel parts of mortar scraps were leached by waste pickling acid and Cu wire was recovered as pure Cu in the process. Pickling acid solution after leaching could be recycled in an ordinary process for waste pickling acid solution. High grade FeSO4 agent could be produced using H2SO4 as a pickling solution.

Jan 1, 2004

By David Green

"This paper describes Outokumpu's Tank Cell concept using the unit reactor principle and operating experience gained in various applications. Presently the tank cells used range in size from 35 t pilot size to 100 m' (3500 cuft). The paper discusses operating experience and results from commercial installations in copper and zinc rougher and cleaner services.The key feature of the Tank Cell described is the effective control of the froth phase and resulting possibility to operate on an improved grade recovery curve by manipulating the control variables."

Jan 1, 1995

By D. Kao, J. Gogal, S. Humphrey, T. Byrne, M. Davoodi

"High total and dissolved uranium values were noted in the process water at the Cigar Lake Operation (CLO) during early production start-up period, whereas significant levels of dissolved uranium had not been observed previously at similar operations. The excess dissolved uranium resulted in higher demands on the water treatment plant, along with higher operating costs, environmental risks and some unrealized revenue potential. A species balance indicated that uranium was leaching into solution in the grinding, dewatering, and storage circuits under normal operating conditions. Jet boring, water recycle, ball milling, and the use of Pachuca tanks for ore storage results in a highly oxidative environment, which is favourable to leaching.This paper will outline the testwork performed to identify the conditions under which the uranium leaches into solution and to determine required conditions for uranium precipitation. Maximum uranium leaching was found to occur under normal operating conditions (pH ranging from 7.0 to 8.5); testwork indicated that both lowering and raising the pH can significantly reduce the uranium leaching. Analytical results combined with the batch scale testwork indicate that the uranium solubility is associated with carbonate species in the ore. Uranium precipitation was maximized at pH values greater than 10.5 or less than 6, corresponding well to carbonate leaching and precipitation values from literature. Higher precipitation efficiencies were noted at high pH ranges.As a result of this work, a pH control system has been implemented in the Pachuca storage vessels and thickener prior to water treatment plant on a trial basis. Caustic soda is recommended for pH control due to ease of operation, economic viability and material requirements and downstream constraints."

Jan 1, 2016

By M. J. Baker

Energy and Minerals Australia Ltd are undertaking a study of the recovery of uranium from the Mulga Rock Deposits in Western Australia. Approximately 80-90% of uranium identified to date is present as tabular layer up to 5 m thick within a lignite seam 30 m to 50 m below surface. Other metals are also present. Metallurgical studies at ANSTO Minerals laboratories in Sydney have focused on identifying a suitable uranium leaching process and assessing the possible downstream impacts of the organic material in the ore. The extraction of other metals has also been examined. This paper provides the results of testwork performed at ANSTO to date.

Aug 1, 2010

By X. Cao, X. -G. Chen, K. Liu

Due to the detrimental effect of platelet iron-rich intermetallics on mechanical properties (particularly ductility) in cast alloys, it has been essential to transform these phases into Chinese script morphology. In the present work, the effects of Mn and/or Si addition and cooling rate on the phase transformation of the iron-rich intermetallics in 206 cast alloys with different Fe contents ranging from 0.15 % to 0.5 % were systematically investigated. The results obtained showed that platelet ß-Fe and Al3(FeMn), Chinese script a-Fe, Alm(FeMn) and Al6(FeMn) can be observed in the 206 cast alloys, depending on the Fe, Mn and Si contents as well as the cooling rate. It was found that the addition of either Mn or Si favors the formation of Chinese script iron-rich intermetallics but inhibits the precipitation of the platelet phases. In addition, the combined addition of both Mn and Si has a synergistic effect on the phase transformation. Furthermore, there exists a critical cooling rate to effectively suppress the formation of platelet iron-rich intermetallics for a given alloy. The threshold cooling rate decreases with increasing Fe, Mn and Si contents. Casting process maps are established to correlate the intermetallics precipitated with alloy chemistry and cooling rate for 206 cast alloys containing various Fe levels.

Jan 1, 2014

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 Y. Kocaefe, D. Bhattacharyay, D. Kocaefe

The carbon anodes used in the electrolytic production of aluminum are made of petroleum coke, recycled anodes and butts, and coal tar pitch. Due to technological advances in the aluminum production technology, aimed at increasing production and decreasing energy consumption and greenhouse gas emissions, better quality anodes are required. Presently, the anode quality is evaluated by visual inspection and the analysis of a small core taken from 1.5-2% of the anodes produced. The visual inspection is susceptible to human error and limited to surface imperfections. The analysis of cores takes time, and therefore, it is difficult to determine the existence of a problem and intervene at the right time. In addition, the core does not represent the whole anode due to the non-homogeneity of anodes. A validated online anode quality control system can highly improve the situation. In this article, an electrical resistivity measurement method developed for this purpose is presented.

Jan 1, 2014

By D. T. A. Symons, M. M. Kapnistos

"Gravity profiles were established over five known Middle Silurian pinnacle reef s in Lambton County, southwestern Ontario. The profiles were approximately 3 km long, with stations every 60 m. Four fairly recent technological developments were used which now make the gravity method relatively efficient and inexpensive compared to the techniques available two decades ago. These are: (1) a La Coste-Romberg model G gravimeter to measure the gravitational attraction with a sensitivity of 0.01 mgal; (2) a Sokkisha model B-2 semiautomatic engineers level to measure the station elevations with an accuracy of 0.5 cm; (3) a Huntec FS-3 hammer reflection seismograph to determine the overburden thickness to an accuracy of ± 7%; and (4) a modern microcomputer to process the data sets and mathematically filter the gravity values. Thus, two men can measure and analyze approximately 1 km of profile per day and obtain the residual gravity profile to an accuracy of ± 0. 05 mgal. Positive gravity anomalies of 0.17 to 0.72 mgal were observed along all five profiles that approximately delineate the dimensions of the known pinnacle reefs, which have an average height of 120 m, diameter of 1500 m and depth to top of 575 m. The relative ease of the gravity survey method makes it a cost-effective technique for hydrocarbon exploration in southwestern Ontario. IntroductionPinnacle reefs are important sources of oil and gas. Although the pinnacle reefs in southwestern Ontario are small, they may contain commercial pools of oil and gas because of their proximity to refineries. They are also useful for subsurface storage of gas to meet the winter surge in gas demand.At present, geophysical exploration for new pinnacle reefs is done primarily by relatively expensive seismic methods, which are also limited in southwestern Ontario by prohibitions on blasting. Gravity methods of exploration were attempted more than two decades ago in this region. (Pohly, 1954); however, the level of technology at that time made the method marginal in sensitivity and quite expensive. Several subsequent developments- gravimeters with greater sensitivity and operating ease, ""self-levelling"" levels for elevation control, hammer seismic reflection units for determining overburden thickness and portable microcomputers for efficient data analysis-have significantly improved the precision and cost effectiveness of the gravity method. Five known pinnacle reefs were selected in Lambton County, southwestern Ontario (Fig. 1), to test the effectiveness of integrating these developments to locate and define additional reefs. Isolated reefs were chosen to avoid the problem of the gravity effect s of one reef interfering with those of a neighbouring reef. The surveys were facilitated by choosing reefs with a concession road passing directly over them ."

Jan 1, 1980

By M. C. Bluteau, G. P. Demopoulos

Arsenic reports in the effluents of many non-ferrous metallurgical operations. The production of scorodite, a crystalline ferric arsenate, is considered as an attractive option for the fixation of arsenic from aqueous effluents. However, scorodite solubility and long-term stability in the pH region of interest for tailings disposal have not been thoroughly investigated. In this study the long-term stability of scorodite in the pH 5 to 9 region and the mechanism of scorodite dissolution were studied. Construction of eh-pH diagrams indicated that scorodite stability is highly dependant on the nature (stability) of co-existing iron-hydroxide/oxyhydroxide. It was also found that when scorodite dissolves, a ferrihydrite phase having very small particles size (nano-scale) forms and that the growth and crystallization of this material are delayed by the presence of arsenate even under accelerated (75°C) ageing conditions. Around neutral pH and ambiant temperature (22°C) scorodite seems to reach an equilibrium with ferrihydrite after 48 weeks yielding soluble arsenic concentrations < 5 ppm.

Jan 1, 2004

By O. Moselhi

The purpose of this research is to evaluate the impact of Building Information Modeling (BIM) on Just-In-Time (JIT) material delivery, with a focus on how the use of BIM can help improve efficient implementation of JIT and reduce the cost of material management. Previous research and a number of case studies have addressed the positive impact of BIM on construction at large but none focused on JIT in construction. This paper presents a methodology for selecting reliable material vendors. It also utilises the integration of BIM and scheduling software to generate quantities of material and its required delivery time to improve the flow process and improve its reliability to minimise related delays and productivity losses arising from idle and non-productive time of equipment and labour on jobsites. 4D visualization is utilized to support coordination and timing of JIT material deliveries in an effort to minimize congestion on job sites. Case studies on JIT material deliveries are presented and the impact of BIM implementation on reducing the cost of material management is evaluated. The joint effect of BIM and JIT on quality control, elimination of waste, reduction of inventory buffers, and on relationships with material vendors are evaluated by analysing and comparing data from case studies. The paper also presents a methodology based on multi-attribute decision criteria for modelling the selection criteria for material vendors. The model can assist in ranking vendors not only based on cost and quality but also on their reliability in delivering material on time.

Aug 1, 2013

By Liu Tao, Wang Wei, Liao Wenjiang, Yang Weiyan, Tang Bin

Side-blown Furnace technology is a developing technology and was developed very quickly in China in recent years, dozens of reference smelters can be found for the treatment of copper concentrate, copper slag, Lead slag, zinc leaching slag and different kinds of slurry. This paper introduces the working principle of the technology, displays the innovations and specifications of China Nerin's SBF technology, gives examples of the typical reference smelters, and looks ahead to future applications. INTRODUCTION Side-blowing furnace smelting process The side-blowing furnace smelting process (SBF process) is one of the bath smelting process with independent intellectual property rights of China Nerin. This process was originally applied to treat copper concentrate and high-lead slag. The SBF process includes two categories, i.e. to treat copper concentrate and to treat industrial solid waste. Up to now, the SBF process has been applied in around 5 million tons of copper concentrate processing capacity and 20+ plants with high-lead slag reduction process. In recent years, SBF process has been gradually used in zinc leaching slag, electroplating sludge, industrial solid waste (e.g., various metallurgical slag), and electronic waste disposal. The basic principle of SBF process is that the material to be treated is directly charged to bath through charging hole with crushed coal and flux, then, enriched oxygen air would be sent to slag level (Vanyukov/Jifeng style furnaces)or matte level (Baiyin style furnaces) via primary tuyere. In this case, the material completes matte/slag metallurgical reaction of gas-liquid-solid interaction under vigorous mixing, and separate matte and slag at the bottom of furnace hearth. With the help of secondary tuyere, the low-pressure air or enriched oxygen would be provided for secondary combustion in the freeboard. The core of SBF process is process parameter control and engineering design of SBF. Presented as a fixed rectangular type, the SBF is a metallurgical furnace consisting of copper water jackets and refractory material. The SBF is consisting of hearth, middle of furnace and furnace top with the sequence from bottom to top. The middle of furnace itself can be further divided into bath area and post-combustion area with primary tuyere and secondary tuyere at both sides. The furnace hearth is made of refractory bricks, which are fused and rebonded Mg-Cr brick, Mg-Cr brick and clay brick from inside to outside. The furnace top adopts a steel water jacket with charging hole and uptake shaft. The water-cooled partition wall is placed at uptake shaft and near charging hole.

Jan 1, 2019

By R. G. L. McCready, R. O. van Everdingen, M. Kalin, R. van Everdingen

"This paper is based on data generated between October, 1986 and October, 1989, during the implementation of an Ecological Engineering close-out for a zinc mine in Northern Ontario, where 690000 tonnes of tailings contain 41.1% pyrite and 4.1% pyrrhotite. The objective was to determine rates of sulphide oxidation and iron precipitation in the tailings. Those rates are relevant for the assessment of the long-term effectiveness of biological systems employed in the removal of heavy metals from contaminated drainage issuing from tailings.Data were collected on the topography and stratigraphy of the tailings basin, subsurface temperatures and groundwater levels, and chemical analyses were made of water samples collected from a number of piezometers. The thickness of unsaturated tailings varied widely between individual piezometer locations; annual maxima ranged from 0.67 m to 3.55 m, and annual minima from 0 to 2.68 m. Sulphate concentrations ranged from 36 mg/L to 20180 mg/L; iron concentrations from 0.36 mg/L to 9938 mg/L; and zinc concentrations from 0.33 mg/L to 1123 mg/L.The geochemistry of the piezometer samples suggests that some of the initial Fe content, resulting from metal sulphide oxidation, is subsequently precipitated in the tailings pile and, possibly, in the underlying unconsolidated sediments, probably in the form of iron-hydroxide and Na-jarosite. Other metals such as Zn may be co-precipitated with Fe. The discharge of a portion of these metals to the environment would be delayed by this process. Some of the initial sulphate may also be lost from solution, probably by precipitation of gypsum; approximate saturation degrees for gypsum ranged from -3.27 to +0.47. The precipitated minerals will somewhat decrease the porosity and permeability of the tailings.Sulphide-oxidation rates, calculated using the analytical results and the estimated amount of annual recharge at the tailings site, average 0.0057 mol/kg/yr. Calculated iron-precipitation rates average 0.000386 mol/kg/yr. It is concluded that the characteristics of seepage from mining wastes may change with time, reflecting the solubilization of precipitated secondary minerals."

Jan 1, 1992

"Eastern Canadian thermal coal mined at Minto, New Brunswick, and in western Cape Breton at St. Rose, Inverness County, Nova Scotia, contains 6-8 per cent sulphur. Both coals are high volatile bituminous. types. The Minto coal averages 18 per cent ash, 7 per cent sulphur and has a Btu rating of 11,900 per lb. Pyritic sulphur accounts for 75 per cent of the total sulphur and the remainder is largely organic; the amount of sulphate sulphur is negligible. This means that in a 7 per cent sulphur coal, 2 per cent is organic and 5 per cent pyritic sulphur. Pit-head St. Rose coal contains approximately 10 per cent ash, 7 per cent sulphur and 11 ,800 Btu/lb. The distribution of sulphur is different to that of Minto coal because about 12 per cent sulphate sulphur is present. Thus, a 7 per cent sulphur coal would contain 4 per cent pyritic, 2 per cent organic and 1 per cent sulphate sulphur.The iron sulphides, pyrite and, to a lesser extent, marcassite occur over a wide size range from large sulphur balls to crack fillings, lenses, and individual crystals and framboids. Coarse-grained pyrite and sulphur balls are easily separated during washing. It is the fine grain sizes, intimately mixed with the coal constituents, that are difficult to separate. Quantimet analyses of the fine grains in coal from both localities showed that about 50 per cent were smaller than 30 micron(1).No efforts have been made to wash the Inverness coal of Nova Scotia and in 1980 washing ceased in New Brunswick. Previously, the Minto coal was processed in an antiquated jig circuit which reduced ash from the strip operation run-of-mine value of more than 20 per cent to less than 18. More effective removal of ash and sulphur could clearly be obtained. Laboratory tests on both Minto and St. Rose coal have shown that ash rejection rates of 40 to 50 per cent at yields of 70-80 per cent were possible(2), Little information on sulphur removal was available."

Jan 1, 1981