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By B. Hart, D. J. Miller, J. T. Francis, M. C. Biesinger, Smart. R. St. C.

Diagnosis of the surface chemical factors playing a part in flotation separation of a valuable sulfide phase requires measurement of the hydrophobic and hydrophilic species that are statistically different between the concentrate and tail streams. Time of flight secondary ion mass spectrometry (ToF-SIMS) can be used to identify sufficient particles of a specific mineral phase for reliable statistics determining a mean value for each species with 95% confidence intervals (1). Using the region of interest (ROI) facility in the Tof-SIMS software, a mass spectrum from each particle, at 1-2 monolayer sensitivity, is recorded and stored. This analysis is reported for a chalcopyrite / pyrite / sphalerite mineral mixture conditioned at pH 9 for 20 minutes in order to study transfer of copper from chalcopyrite via solution to the other two mineral surfaces since this mechanism can be responsible for their inadvertent flotation in copper recovery. Analysis from mineral selection based on specific ToF-SIMS signals (eg. Pb, Zn, Cu, Fe, Fe/Cu) indicated no statistical difference in the copper intensities on pyrite and sphalerite after this conditioning. Principal component analysis (PCA) of the ToF-SIMS imaging data identifies combinations of factors strongly correlated (positively or negatively) in images or spectra from mass spectra recorded at each of 256x256 pixels in a selected area of particles. PCA is a better method of selecting minerals due to multi-variable recognition. It has clearly separated a statistical difference in copper intensities between the sphalerite and pyrite phases. The method has been extended to samples from an operating plant again with excellent phase recognition and diagnostic surface chemistry.

Jan 1, 2004

By B. Van den Bogaert, K. Binnemans, T. Van Gerven

Europium is one of the most critical rare-earth elements due to the limited supply of this element combined with a high demand for red lamp phosphors. Therefore, the recycling of europium from end-oflife lamp phosphors has become increasingly important. Photochemical reduction of europium(III) to europium(II) and subsequent removal from rare-earth mixtures by precipitation as EuSO4 is a very selective and efficient method to recover europium from binary europium/yttrium solutions. It is shown that full separation of europium and yttrium is feasible from laboratory prepared non-equimolar Eu/Y mixtures up to a ratio of 1/20, which reflect the composition of red lamp phosphors. Optimal conditions were determined at pH 4 with isopropanol as a radical scavenger, which is a less harmful and toxic compound than the commonly used formic acid scavenger. Europium removal efficiencies of more than 95% were achieved, with a purity of 98.5% of the EuSO4 precipitate. The irradiance of the used light source, expressed in mW/cm2, has a large impact on the illumination time needed to remove europium from the solution. It is observed that higher irradiance results in a shorter induction time, i.e. a period during which virtually no europium is removed, and a faster removal rate once the induction time has passed. The photochemical separation technique was applied to recover europium from leached industrial red lamp phosphor (YOX) powder, with a Eu/Y ratio of 1/30. Europium recovery of 50% was reached with a purity of 96%, proving the feasibility of this method for the recycling of europium from end-of-life lamp phosphors.

Jan 1, 2016

By Yongqiang Liu

Background For refractory gold ores with high carbonate contents ! Acid pressure oxidation ! High acid consumption (if low sulfur content) ! Low oxidation efficiency due to CO2 in autoclave ! Problems with slimy precipitates (gypsum, etc.) ! Alkaline pressure oxidation ! Difficulty in fixing arsenic ! Low gold dissolution due to iron hydroxides/oxides coating ! High reagent costs Summary ! Carbonate and sulfide minerals had similar floatability across the pH range tested (5 - 12) using sodium oleate as a collector; ! Thioglycollic acid or citric acid depressed the flotation of pyrite but could not depress chalcopyrite when used alone; ! Combination of thioglycollic acid and citric acid had a much stronger depressive effect, and the mixture depressed chalcopyrite as well as pyrite between pH 8 and 11 without affecting the flotation of calcite and dolomite; ! Calcite could be separated from chalcopyrite and pyrite; dolomite could be separated from pyrite but not from chalcopyrite under the tested conditions.

Apr 1, 2005

By Martin P. Raffield

Placer Domes? Campbell Mine, situated in northwestern Ontario, is undergoing an assessment of the efficiency of the operation which is necessitated by the low gold price and a reducing ore reserve grade. A decision has recently been taken to move away from a functional based departmental structure (underground, engineering, geology, etc.) towards a team-based system where crews, engineers, geologists and supervisors are responsible for the planning and operation of a particular area of the mine. The objective is to improve communication and understanding of the goals and achievements and to ensure a forum is available for the generation of ideas. It is intended to increase the accountability and decision-making ability of the teams in an effort to achieve the mines? safety and production targets. This paper presents a critical review of the progress of this organisational change process and its successes and failures at the time of writing.

Oct 1, 2001

By D. B. Johnson

Acidic, metal-rich waters generated at working metal mines and abandoned mine sites are generally considered to be major pollutants of the environment. However, the metals they contain often have significant value of their own, or as sources of useful mineral products. We have developed novel bioreactor systems that facilitate the selective recovery of various transition metals (e.g. copper, zinc and iron) as defined minerals that can be recovered and recycled. The bioreactors use novel species of acidophilic bacteria. Ferrous iron is oxidised by Ferrovum myxofaciens, a specialist bacterium that forms large amounts of exopolymers and grows as filamentous streamers in flowing mine waters, and the ferric iron generated is precipitated as the mineral schwertmannite, a small proportion of which is used to remove any arsenic present in mine water. Copper and zinc are precipitated as sulphides using H2S generated by consortia of acidophilic and acid-tolerant sulphate-reducing bacteria in a continuous flow, on-line low pH bioreactor. Transition metal sulfides can be segregated by precipitating them, either on-line or off-line, at different pH values. The modular units that have been developed can be configured to treat mine waters of different chemistries. A hypothetical acidic (pH 2.5) mine water stream containing 500 mg/L iron, 100 mg/L of copper and zinc, 50 mg/L of aluminum and manganese, 2 mg/L of arsenate, and discharged at a rate of 10 L/s, is used as an example of the potential application of the mineral-generating bioreactors. The environmental benefits and economic implications of considering mine waters as resources rather than wastes are discussed.

Aug 1, 2013

By N. R. Andrade-Gonzalez

The present work was performed on four alloys containing Al-6 2 wt pct Si-3 5 wt pet Cu, with magnesium in the range of 0.02-0 40 wt pct, and strontium in the range of 0-165 p p m Tensile bars were cast in a permanent mold (ASTM B108-160) and heat treated at 495°C for 4 hours, followed by quenching in hot water. Two different artificial aging temperatures were applied at 180 °C and 220 °C for times from 0 5 h up to 8 h Tests were conducted with the intent of determining how the mechanical properties of an aluminum-based 319 alloy are affected when aging time and temperatures are varied In general, it is seen that the alloy does not exhibit the common peak-overaged aging condition due to the presence of several coexisting phases, indicating that they form through complex eutectic reactions late in solidification.

Jan 1, 2004

By R. Grau

"After commissioning and start-up of the first 500m3 TankCell® flotation cell in 2014, the over 300m3 mechanical flotation cells have earned their place in large-scale flotation operations. These 500 to 630m3 cells, designed for projects with large throughputs, are proven to provide savings in project capital and operational expenditure through savings in foot print, energy consumption, and less equipment to install and maintain. Addition to savings in different phases of a project, these cells provides operational flexibility and has shown improvements in metallurgical performance. In this paper a case study from Kevitsa TankCell® e500 installation and Buenavista del Cobre TankCell® e630 installations will be given.INTRODUCTION After development (Grönstrand and Bourke, 2008), characterization (Morales et al. 2009; Yanez et al. 2009; Grönstrand at al. 2009), validation (Elgueta et al. 2009; Coleman and Dixon, 2010), and more than 350 industrial installations of the Outotec TankCell® e300 flotation cell, the well proven energy efficient TankCell® product family introduced the TankCell® e500 forced-air flotation cell late June 2012 (Outotec.com, 2012). The introduction of the 500 m3 flotation cell followed by introduction of a 630 m3 flotation cell, TankCell® e630, in October 2014 (Outotec.com, 2014). These large flotation cells are designed for projects with high throughputs where the number of cells needed for operation with smaller equipment would become large. The benefits of this size of flotation cells comes from the lower capital expenditures due to lower equipment costs, savings in plant footprint, less installation work with less auxiliary equipment, lower energy consumption, and less units per installation resulting in less components, spare parts and maintenance.The first TankCell® e500 was commissioned and taken into operation in October 2014 at FQML Kevitsa Cu-Ni-PGE concentrator, nowadays owned by New Boliden. The first TankCell e630 was taken into operation in January 2018 at GrupoMexico’s Buenavista del Cobre Cu-Mo concentrator. The start-ups of the first TankCell® e500 and TankCell® e630 followed with test work where the hydrodynamic performances of the cells were characterized and metallurgical performance studied. The results of the TankCell® e500 test work were presented in detail by Mattsson et al (2015a; 2015b) and TankCell® e630 by Grau et al. 2018. In this paper the metallurgical improvements achieved with the large cell installations will be presented."

Jan 1, 2019

By M. A. Roche

The property of the Hudson Bay Mining & Smelting Company, Limited is located at Flin Flon lake, 85 miles northwest of The Pas, Manitoba, on the Manitoba-Saskatchewan boundary. The area is at latitude North 54°, and is approximately 1,000 feet above sea level. The ore-body occurs in amygdaloidal greenstones, which are to be referred to the earliest basic volcanic flows in the district. It was discovered in an outcrop on a point of land jutting into Flin Flon lake, and subsequent diamond drilling proved that it extends under the lake both to the north and south of the point of discovery. After the taking of soundings from the ice during the winter months, it was estimated that l,000,000 tons of overburden, mainly mud and clay, would have to be removed to expose the underlying ore. Flat diamond-drill holes indicated that the ore-body was separated into more or less independent lenses by horses of unmineralized greenstone, and that in places the overall width, including horses of waste, reached 450 feet. These several] conditions were the main factors influencing the management in their decision to adopt an open-cut method for the mining of the upper portion of the ore-body. Before it was possible to commence stripping operations, it was necessary to dam-off the eastern portion of Flin Flon lake, instal pumps, and de-water the dammed-off area. Dams for this purpose were constructed of mine waste rock and clay filler from nearby hillsides. Material for the bottoms of the dams was taken across Flin Flon lake in hopper-bottom barges. Trestles were then built on the dam bottoms and dams were complete by the time trackage was available. De-watering commenced in April, 1930, and was completed by the latter part of May of the same year. Estimated pump output for the period was roughly four billion gallons. Two Morris 10-inch dredging pumps were used, direct-connected to 250 h.p. electric motors. Individual pump capacity was rated at 3,000 g.p.m. against a 150-foot head. Average head for the operation was 50 feet, which increased the total output considerably. The pumps were mounted on floating barges in cribbings of piling driven at the lowest points in the lake bottom.

Jan 1, 1933

By A. M. Simons

Cyanide destruction by Caro’s acid is one process commonly employed by gold operations to meet regulatory requirements and/or the International Cyanide Management Code compliance for weak acid dissociable (WAD) cyanide in cyanidation tails or waste water from such operations. Typically smallscale bench tests to evaluate and assess the suitability of the Caro’s acid destruction process are conducted. Additionally, the experimental procedure used during these preliminary investigations may also differ from that implemented at the full-scale. This paper presents the results from a fundamental investigation of the Caro’s acid process to establish a more detailed understanding of the impact that the experimental procedure has on the destruction of cyanide. In particular, it was found that the control of pH was important to avoid copper(I) cyanide precipitation at low pH and maximise WAD cyanide destruction. Residual peroxide in the preparation of Caro’s acid has the potential for subsequent cyanide destruction and could be exploited.

Jan 1, 2014

By A. L. Mackie

Mine water from base metal mines is generally characterized as having high concentrations of heavy metals and low pH, resulting in the need for treatment prior to discharge to receiving waters. In this study, two high-rate clarification processes were evaluated at bench-scale: the high density sludge (HDS) process and sand-ballasted flocculation. High-rate clarification processes generate larger, denser flocs which settle more quickly than those formed in conventional flocculation processes. The HDS process uses recirculated sludge in order to seed floc formation, whereas ballasted flocculation uses microsand. Both of these high-rate processes require the addition of quicklime or hydrated lime to increase pH and allow for the formation of insoluble metal hydroxides, which can then be removed in the clarification stage. Previous research has shown that cement kiln dust (CKD) can effectively replace quicklime in conventional sedimentation processes for metals and acidity reduction to meet discharge guidelines (Mackie & Walsh 2012). CKD is an alkaline by-product of cement manufacture that has fine particle sizes and varying free lime concentrations depending on the manufacturing process. The lower solubility (i.e., free lime content) of CKD requires larger doses of material to be added to reach treatment pH targets for metals precipitation. The purpose of this study was to evaluate the treatment efficacy of high-rate clarification processes for mine water treatment, compared with conventional sedimentation, at bench-scale with conventional (i.e., lime) and novel (i.e., CKD) pH adjustment additives. Results of the study showed that all treatment processes (i.e., HDS, ballasted flocculation, and conventional sedimentation) were able to reduce target metal concentrations to well below Canadian guidelines (i.e., total zinc and total nickel < 0.5 mg/L, total copper < 0.3 mg/L) using either CKD or lime. Additionally, mine water samples treated with CKD generated lower sludge volumes than those treated with lime (i.e., 50 versus 100 mL for conventional sedimentation and 100 versus 200 mL for HDS) even with increased concentrations of solids introduced during treatment. This is most likely due to slower neutralization rates when using CKD, due to its lower solubility, as well as finer particle size. The sand-ballasted flocculation process was able to reduce final turbidity in CKD-treated samples while the HDS process did not when compared to conventional sedimentation, making the ballasted flocculation process preferable for reducing final solids concentrations in CKD-treated mine water.

Aug 1, 2013

By S. Hobo, M. Yagisawa, T. Uchida, C. Tokoro, T. Kato

In this study, quantitative modeling was carried out for the treatment of simulated waste water containing As(V), Zn(II) and Hg(II) as toxic elements, and Fe(III), Na(I) and sulfate as coaxing ions. The objective was to predict the pH and residual concentrations of all the elements in solution after the neutralization/co-precipitation treatment. To accomplish this, the removal mechanism for As(V) and Hg(II) by ferrihydrite precipitation was first investigated for simulated waste water containing only As(V) or Hg(II). From the experimental results, it was confirmed that the removal mechanism involves not only surface complexation but also surface precipitation. However, surface complexation is the main mechanism for As(V) and Hg(II) removal to meet the target levels regulated in Japan. Next, the surface complexation model was constructed for the removal of As(V) and Hg(II) by ferrihydrite. The specific surface area and site density were determined from reference values proposed by Dzombak and Morel (1990). By comparing the experimental and calculated results, it was confirmed that our constructed model could successfully represent the experimental results. Furthermore, the surface complexation model was coupled with chemical equilibrium calculations and applied to the neutralization of simulated waste water containing As(V), Hg(II), Zn(II), Na(I), Fe(III) and sulfate. The constructed model could successfully represent the pH edge for As(V), Hg(II), Zn(II), Fe(III) and SO42- removal. In addition, the constructed model could represent the ion balance. Thus, our constructed model is useful to estimate the amount of neutralizer that is needed to achieve a target pH.

Jan 1, 2016

By J. J. Ferreira, M. L. Thurston, I. L. Chinn, D. M. Rose

"Concerns about using microdiamonds for resource estimation have been raised by workers because multiple diamond populations exist in many parts of the mantle source region, small diamonds in kimberlite could be exposed to proportionately greater levels of resorption and modification, and euhedral microdiamonds could crystallize immediately prior to kimberlite eruption. This paper addresses these concerns; discusses the geology of the mantle, the principal diamond host rocks, and the impact of mantle processes; compares micro- and macrodiamond properties and features; and outlines steps to identify and mitigate the risk of diamond resorption and its impact on the diamond grade-size relationship.RÉSUMÉ Des travailleurs se sont interrogés sur l’utilisation de microdiamants pour estimer la ressource; en effet, de multiples populations de diamants existent dans plusieurs secteurs de la région source dans le manteau. Des petits diamants dans la kimberlite pourraient être exposés à des niveaux proportionnellement supérieurs de résorption et de modification; de plus, des diamants idiomorphes pourraient cristalliser immédiatement avant l’éruption de la kimberlite. Le présent article traite de ces questions, discute de la géologie du manteau, des principales roches-mères des diamants et de l’impact des processus dans le manteau, compare les propriétés et les caractéristiques des micro- et des macrodiamants et définit les étapes pour identifier et mitiger le risque de résorption des diamants et son impact sur la relation entre la taille et la qualité des diamants."

Jan 1, 2016

By Georgy A. Cherkashov, Andrey V. Efimov, Yury S. Borodaev, Nadezhda N. Mozgova, Sergey G. Krasnov, Tamara V. Stepanova, Alexander M. Ashadze

"Abstract - A horizontal mineralogical-geochemical ore zonation with a southeast to northwest trending succession of Cu and Fe (Zn) main zones has been discovered in the Logatchev hydrothermal field (14°45??N Mid-Atlantic Ridge). The major minerals are pyrite, chalcopyrite, bornite, isocubanite, digenite and chalcocite. Zn-sulfide, marcasite and covellite are less abundant. Rare minerals are native copper, zincian copper and cobalt pentlandite (first found in oceanic massive sulfides), Cu and Cu-Co-bearing Fe-disulfides. Two groups of the main sulfide assemblages with different copper contents are recognized: Group I comprises assemblages with primary sulfides (isocubanite, chalcopyrite, pyrite and Zn-sulfide; Cu up to 35 wt% in Cu-bearing minerals); Group II contains assemblages with secondary Cu-rich sulfides (bornite, digenite, chalcocite; Cu ~60 wt%) as well as rare minerals (cobalt pentlandite, native copper and zincian copper). The assemblages of Group I formed at a temperature of about 300°C; the sulfur fugacity (log fs2 atm) at 300°C is probably 9.9. Relations between minerals of this group are contradictory, attributed to non-equilibrium environments, and no unified sequence of crystallization of minerals has been determined. Minerals of Group II replace, rim or cross the assemblages of Group I. Group II minerals crystallized in a distinct sequence (cobalt pentlandite-bornite-digenite- chalcocite-native copper), with increasing copper content from the start to the end of the depositional sequence. This may correspond to pH from 7 to 8 near Eh = -0.2 at 250°C. Minerals of this group were generally formed under hypergene alteration processes. Compositions of ore minerals were studied by means of electron microprobe analysis (EMPA) (150 analyses). Narrow composition fields were revealed in all main sulfides, which comprised known experimental data. ZnS contains 6.0 to 28.0 mol.% FeS, which is close to data known for other hydrothermal massive sulfides from the Mid-Atlantic Ridge (MAR). A common admixture in ZnS is Cu (0.16 to 1.32 wt%). Rare grains of unusual anisotropic Fe-disulfides, (Fe0.95Cu0.05)S2 and Cu(Fe,Co)9S20, were found among the ore minerals."

Jan 1, 1999

By M. Niinae, F. Nakahara, T. Kawamoto, T. Suzuki

"MgO was chosen as an As(V) immobilization agent and a series of immobilization experiments was performed to obtain insights into the behavior of As(V)and MgO during leaching tests. Our experimental and modeling results demonstrated that As(V) immobilization by MgO consists of the following steps: (i) an increase in soil pH, (ii) desorption of As(V) from the soil, and (iii) the re-immobilization of As(V) by MgO/Mg(OH)2particles. Regarding the behavior of MgO, the modeling results showed that when the MgO dosage was 25 mg MgO/4g-drysoilor less, the majority of MgO was used to increase pH, and less than 1% of MgO was used to sorb As(V), which was consistent with the result of leaching tests showing that a high level of As(V) was leached at the MgO dosages. On the other hand, when the MgO dosage was above 25 mg MgO/4g-drysoil, the percentage of MgO used for As(V) sorption increased up to 35%, and correspondingly, the As(V) leaching level decreased to below 0.01 mg/L As at an MgO dosage of 75 mg MgO/4g-drysoil.INTRODUCTIONOne of the major arsenictransport pathways causing groundwater contamination is the migration of arsenicfrom artificially or naturally contaminated surface soils. Therefore, in this study, the immobilization of arsenate (As(V)) in soils was investigated using commercial-grade magnesium oxide (MgO) as a potential cost-effective measurement to prevent the occurrence of groundwater contamination with As(V).With respect to the use of MgO for remediating As(V)-contaminated environmental media, MgO has been used in several studies to remove As(V)from water(Yu et al., 2011; Jia et al., 2013; Tresintsi et al., 2014). Although these studies demonstrated that MgO effectively removes As(V)from water in water-MgO systems, the behavior of As(V)in water-soil-MgO systems has not been evaluated in the literature, and several questions remain to be answered to comprehensively evaluate the use of MgO as an As(V)immobilization agent in soils. For instance, as is well-documented in the literature(Ford, 2002; Lenoble et al., 2002; Zeng et al., 2008), iron oxy-hydroxide (FeOOH) is one of the important adsorbents for As(V)in both natural and engineered systems. Therefore, it is anticipated that the presence of FeOOH in soils significantly influences the behavior of As(V)in water-soil-MgO systems and consequently, the immobilization performance by MgO. Another important question to be answered is the behavior of MgO during the immobilization treatment. In our previous studies (Suzuki et al., 2013a, 2013b), commercial-grade MgO was demonstrated to effectively immobilize lead and fluoride, and the immobilization effectiveness was indicated to last more than 100 years against the exposure to acid rain (pH 4.0). However, these studies focused on the behavior of contaminants. As a result, little is known about the behavior of MgO during the immobilization treatment. The lack of understanding of the behavior of MgO during immobilization treatment is one of the main concerns leading to relatively low public confidence in immobilization treatments."

Jan 1, 2016

By L. Xia, B. Hart, K. Douglas

In the flotation of Rare Earth Element (REE) bearing minerals, oxalic acid is reportedly acting both as a depressant and pH modifier. Testing has established the significance of oxalic acid in the flotation process however its specific role in either the recovery or selectivity of REE over their gangue minerals is not well understood. Pulp pH reduction trials with alternative acids have not shown the same effect on the REE mineral recovery or the depression of gangue phases. This work examines the effect of oxalic acid on the surface of gangue minerals (quartz and carbonates (dolomite and calcite)) in a series of conditioning tests. Gangue surface analyses by TOF-SIMS indicate that oxalic acid inhibits the transfer of secondary ions generated during the conditioning process from one mineral phase to another. In this regard, the oxalate anion acts to fix ions in solution through chelation, limiting their participation in surface adsorption.

Jan 1, 2014

By W. D. Gould, A. Kapoor

Acid mine drainage (AMD) is characterized by low pH and high concentrations of sulfate and dissolved metals such as iron, manganese, aluminum, zinc, and copper. Chemical treatment of AMD achieves pH neutralization and toxic metal removal but also produces large quantities of bulky sludge that requires long-term storage facilities and monitoring. Chemical treatment of AMD achieves only partial removal of sulfate (SO4) and total dissolved solids. Sulfate reducing bacteria (SRB) have been used for the removal of sulfate from industrial process wastewaters. The biological sulfate reduction process generates sulfide and alkalinity. The sulfide produced in the biological sulfate reduction process is used to precipitate metals present in AMD as their respective sulfides and the alkalinity generated is used to neutralize the AMD. This review article will present an overview of biological sulfate reduction processes using SRB, bioreactor configurations, AMD treatment studies, and full-scale systems in operation for the treatment of acid mine drainage.

Jan 1, 2004

By Tom Dettweiler

Who We Are A global pioneer in discovery, development and recovery of deep-ocean assets Shipwrecks Deep-sea Minerals Company Overview Founded 1994 HQ ?Tampa, Florida USA Employees 45 Tampa + 150 Abroad Publicly Traded: NASDAQ:OMEX Requires Specific Financial Controls and Reporting

May 1, 2013

By T. Yalcin

"This paper describes a study carried out to determine the behaviour of Cu-Ni mill tailings during natural and flocculated sedimentations. Settling rates were examined under various conditions through standard laboratory batch settling tests. Flocculation was found to improve the sedimentation process significantly, but its effectiveness depended on several factors such as the pulp density of feed, the type and dosage of flocculating reagent, the pH of pulp, the intensity of mixing flocculant with tailings sand the use of stirring during compaction.It is shown that. for a sedimentation process taking place under given conditions, underflow pulp density (P) and sedimentation time (t) are related by the expression P = k.tn, where k and n are constants. A procedure is described for the use of this expression in thickener size estimations. IntroductionOften a considerable proportion of the mill feed is disposed as tailing, because the valuable mineral recovered usually forms a small fraction of the ore. Moreover, wet concentration processes result in liquid wastes that are several times more voluminous than the ore itself. Thus the handling and disposal of these wastes become an important cost item in most milling operations. The principal unit process employed in tailing disposal is solid-liquid separation which is traditionally carried out by gravity sedimentation in thickeners or tailing dams. Direct disposal of tailings into tailing dams is common practice where sufficiently large areas of land are available but it frequently becomes more economical or practical to densify the tailings in a thickener beforehand.Successful thickener operation depends essentially on correct thickener size which is in turn governed by the sedimentation characteristics of the tailings handled. Flocculation can aid the sedimentation process and bring about significant savings in thickener size, but its effective use requires a detailed study to identify the optimum conditions of application."

Jan 1, 1988

By S. Masambi, S. M. Bradshaw, C. Dorfling

The presence of iron in base metal leach solutions complicates nickel and copper recovery processes. Leach solutions are commonly purified by precipitating iron as hematite, jarosite or goethite. Fast oxidation of ferrous to ferric is an important step to remove iron by precipitation at low pH values. This study reviews the ferrous oxidation mechanism and reaction rates in chloride media using molecular oxygen. This work contributes to the development of a better understanding of iron precipitation processing steps, which continues to be an important matter in hydrometallurgy. The specific objectives were to investigate (1) the effect of key process variables (acid concentration, copper concentration, and temperature) on the rate and extent of ferrous oxidation by dissolved oxygen and (2) the oxidation mechanism by varying chloride and hydrogen ion concentrations separately. Batch oxidation tests were performed using synthetic chloride solutions containing 45 g/L Fe and 3 g/L Ni at 50 and 80°C, dissolved Cu concentrations (0.3 to 3 g/L) and HCl concentrations (2 to 4.6 M). Regression analysis indicated that the significance of the effect of different variables on the extent of oxidation achieved after five hours decreased in the following order: HCl concentration > Cu concentration > temperature. Increasing the HCl concentration from 4 M to 4.6 M caused the degree of oxidation achieved after two hours to increase from 58.3% to 98.1%. The catalytic effect of dissolved copper on ferrous oxidation was more significant at low acid concentrations. Experimental data suggest that rapid oxidation of ferrous is possible at high HCl concentrations for two main reasons. First, the formation of ferrous chloride complexes allows ferrous oxidation to proceed without the formation of superoxide as an intermediate product (the rate limiting step in dilute acid solutions). Second, the formation of ferric chloride complexes stabilises the oxidation product.

Jan 1, 2016

By Chester J. Kuryliw

"The Geology of the Cochenour Willans mine, Red Lake district, was described by J. P. Nowlan in the Jubilee Volume. The complexity and intense alteration of the rocks obscured any clear relationship between ore and structure, and Nowlan recognized that future work might greatly modify the ideas then existing. This has proved to be the case. Subsequent detailed work has established the stratigraphic sequence in the Keewatin formations which are the host rocks of the orebodies, and has shown that the principal orebodies are confined to two adjoining bands of tuff.On this basis, it is now possible to map the complex structures with greatly increased accuracy. The amount of drilling and underground exploration required to find new ore has been much reduced, and indicated ore reserves are now substantially greater than at any time in the past. Daily production in 1955 averaged 187 tons per day at 0.578 ounces of gold per ton.The sequence of Precambrian events in the mine area is summarized in the following table:Intrusion of post-ore dykes.Ore formation.Intrusion of post-faulting, pre-ore dykes.Deformation: folding and shearing; alteration; faulting.Timiskaming sedimentation.Unconformity.Keewatin: volcanics and sediments, host rocks of the orebodies, described in detail in the next section.KeewatinFrom oldest to youngest, the Keewatin rocks in the mine area can be divided into six formations, which have been given local names:“Grey"" LavaA fine-grained dacitic to andesitic lava, amygdaloidal and locally containing well formed pillows. Certain areas are sheared and chloritized to a degree that makes identification difficult. The rocks are carbonatized throughout; the most persistent carbonate veins parallel the upper contact. Thickness more than 1,000 feet. (Minor mineralization, type 1 I -See section on Ore Formation)."

Jan 1, 1949