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By Tom Leistner, Urs A. Peuker, Martin Rudolph

"It is well known, that for conventional froth flotation techniques the processing of ultrafine mineral particles is generally inefficient and results in rather low-grade concentrates and relatively high losses of valuable minerals. Therefore, the investigation of other possible methods, which can selectively separate such fine particle systems effectively, is of considerable interest. In this study, the application of two-liquid flotation, a flotation-related process using oil droplets instead of air bubbles, is investigated as a possible processing strategy for the separation of ultrafine particle systems. The investigation involves the testing of the two-liquid flotation technique as simple laboratory-scale batch trials and moreover, the up-scaling to a semi-continuous process by using a modified lab scale flotation column. Magnetite and quartz particles, with particle sizes below 10 µm respectively, as academic mineral mixture and iso-octane and water as the two immiscible liquid phases are chosen for the experiments. To manipulate the wettability of the magnetite particles as well as the interfacial tension of the oil/water interfaces, surface active reagents of fatty acid basis are introduced in the system. The selectivity of the process is characterized by determining the removal of magnetite particles from the aqueous suspension through selective accumulation at the oil/water interface or extraction into the oil phase, respectively. Operational parameters including pH of the aqueous suspension, additional electrolyte addition and surfactant type as well as dosage are varied in order to maximize the efficiency and stability of the process."

Jan 1, 2014

By Michel Brissette, Shaheer Sanuri, Veroljub Mihajlovic

"The main purpose of geometallurgy is to improve the mine planning by mapping hardness and throughput into the mine block model using geostatistics to eliminate the large production fluctuations caused by the ore hardness variability coming from different parts of the pit. However, not all grinding testwork available commercially can be applied to geometallurgy because of large amount of sample required and the associated cost per test. Geometallurgy is now being used in designing grinding mill but as the mining project progress, the accuracy of engineering must improve from 30-35% during the scoping study to 10-15% at the bankable feasibility stage and less than 5% for Engineering Procurement and Construction Management. For SAG milling, the SAG Variability Test (SVT) is an abbreviated version of the standard SAGDesign test developed for this geometallurgical need. The same amount of ore than the original test is ground for three cycles into an open batch SAG test and then the SAG pinion energy is predicted to the standard end point of 80% passing 1.7 mm. For ball milling, a Bond Variability Test (BVT) was also developed using the SAG ground ore from the SVT. The Bond ball mill grindability (Gpb), corresponding to the average of the net grams per revolution from the last three cycles of the Bond test, is also predicted from the third cycle. The relative error for both the predicted SAG ore hardness (WSVT) and Bond Work Index on SAG Variability ground ore (Sv-BVI), in kWh/t, averaged 5.5% and 3.8% respectively compared to the SAGDesign testwork values and are within 7% and 10% respectively from plant benchmark and within 7% from the samples sent to all partner laboratories. Both tests can be continued to measure the true hardness necessary for mill sizing. This article discusses the development of these two new tests, SVT and BVT, their potential use and accuracies in any geometallurgical program."

Jan 1, 2014

By Tingting Li, Guodong Li, Dezhou Wei, Cong Han, Shuling Gao, Yanbai Shen

"The aim of this study is to solve the problem of tungsten leaching from scheelite concentrate using sodium hydroxide in the presence of phosphate by an autoclaving process, which is one of main development techniques for tungsten recovery. To understand the applicability and leaching performance of tungsten leaching from scheelite concentrate, the main work is to investigate the effects of leaching parameters such as initial concentrations of NaOH and Na3PO4, reaction temperature, stirring speed, liquid-to-solid ratio and reaction time on WO3 dissolution rate to obtain the optimal leaching conditions. The chemical composition and phase composition of the samples were evaluated by means of XRF and XRD. The content of WO3 in the leaching residue obtained via washing, filtering and drying was analyzed by thiocyanate spectrometric method. The optimal leaching conditions were found to be NaOH concentration of 6.76 mol·L-1, Na3PO4 concentration of 1.35 mol·L-1, reaction temperature of 180°C, stirring speed of 400 rpm, liquid-to-solid ratio of 2.0 and reaction time of 90 min. The results showed that tungsten leaching rate of 99.20% was reached under the optimal conditions. The technology exhibited superior leaching performance, which not only reduced the consumption of sodium hydroxide but also greatly decreased reaction time in comparison to a conventional autoclaving process. INTRODUCTION Tungsten is an important strategic metal, which is widely utilized in a variety of industries due to its high melting point, superior mechanical properties and heat-resistant performance [1-3]. The chief raw materials for the production of tungsten in nature are wolframite and scheelite [4, 5]. Among them, approximately two-thirds of the tungsten reserves contain scheelite deposits in the world [6, 7]. With the progressive exhaustion of high-quality wolframite resources, scheelite has become a predominant primary resource for the production of tungsten [8, 9]."

Jan 1, 2018

By Regis Texeira, Leopoldo Gutierrez, Vicente Hernandez, Caludia Vidal, Lina Uribe

"Molybdenum is currently the most important by-product of Chile´s copper mining industry. This mineral has gained international relevance over the years, because of its price. At mining deposits in Chile, copper and molybdenum are extracted together and then separated in a concentration process consisting of several flotation steps using sodium hydrosulfide (NaHS) as copper depressant. However, there are environmental issues related to the potential emisions of toxic hydrosulfide gas and bad odours, which affects nearby communities and suppose a risk for operators. This problem has led to the need for development of new technologies to eliminate the use of NaHS in the process of selective flotation of Cu and Mo minerals. In this work, results of flotation tests in which lignin derivatives reagents are used to obtain the selective separation of Cu and Mo minerals by flotation are presented. In this technology molybdenite is depressed by the action of lignin derivatives (lignosulfonates), while copper sulfides remain hydrophobic and float. The use of lignin derivatives in the selective flotation of copper molybdenum minerals represents a non-toxic alternative to NaHS.INTRODUCTIONSeparation of copper sulfides from molybdenite is commonly achieved through a two-stage flotation process. In the first stage the collective flotation of copper sulfides and molybdenite is promoted to generate a collective concentrate which is then treated in a second stage with sodium hydrosulfide (2.5-3.0 kg/t NaSH) to depress copper sulfides flotation without affecting the flotation of molybdenite. As a result a copper concentrate with 30-35% Cu, and a molybdenum concentrate with 50-52% Mo are generated. Although this process is widely used at industrial level, environmental issues related to the risk of H2S generation and bad odors have always been a concern. Thus there is a need in the industry for a more environmentally friendly process to separate copper sulfides and molybdenite."

Jan 1, 2018

By David De Klerk, Maximilian Richter, Thirunavukkarasu Pathmathas, Indresan Govender

We consider the average power dissipation distribution for dense granular flows of an idealised mono-sized charge (5 mm glass beads) in a 300 mm diameter tumbling mill operated in the cascading-to-cataracting Froude regime. By combining the inherent frictional nature of particles within a dense flow regime and noting that tumbling mills are typically characterised by collisional and turbulent stresses, we derive the power dissipation distribution for athermal boundary conditions. The input data to the model (velocity, solids concentration, pressure and flow depth) are obtained directly from non-invasive measurement using a nuclear imaging technique: Positron Emission Particle tracking (PEPT). The power dissipation due shear stresses is shown to be the dominant mode of dissipation in the tumbling mill with up to two orders of magnitude difference between pressure induced dissipation and shear.

Jan 1, 2014

By W. H. Cheung

Nickel (Ni) plays a major role in the production of steel and other major alloys. There are two sources of Ni: laterite and sulphide ores. Global reserves of sulphide ores are being rapidly depleted, while there are enormous reserves of Ni laterite, much of it in Australia. As well as being present in huge amounts, Ni laterites have the advantage of containing cobalt (Co), a valuable mineral. Over the past decade, these factors have been driving the industry to explore the processing of Ni laterite. A route that has been used commercially in processing nickel laterite ore involves the thermal activation of the minerals by pre-reduction followed by ammoniacal leaching (Caron). Although this process has been effective in processing the goethite rich laterite minerals, the higher-grade serpentine-based minerals have been shown to be less susceptible to this process. This has been attributed to the formation of inert olivine phases. In this study, we examined the use of an alternative lixiviant, sulphuric acid, in leaching pre-reduced limonite and weathered saprolite nickel laterite ores. The specific aim of this study was to examine the sulphuric acid leaching of Ni and Co from pre-reduced laterite minerals, and to understand the role of mineral transformations in this metal dissolution. Synchrotron based X-ray diffraction was used to examine the transformation of goethite (FeOOH) to spinels and serpentine mineral ((Mg,Fe)3Si2O5(OH)4) to olivine. Reduction tests were carried out using CO and CO2 reducing gas mixtures and temperatures from 400 °C to 700 °C. The rate of formation and disappearance of specific Bragg peaks during reduction of specific minerals were used to derive an understanding of these solid-state reactions. Laboratory based reduction tests and leaching in sulphuric acid were used to validate the effect of these mineral transformations. The results suggest the versatility of sulphuric acid in leaching nickel from spinels and olivine, which was achieved at the expense of lower selectivity. Cobalt dissolution was found to be dependent on the nature of ferro-cobalt alloy formed during reduction.

Jan 1, 2014

By S. A. Vorobyev, Yu. L. Mikhlin, Ye. V. Tomashevich, A. A. Karacharov, M. N. Likhatski1, A. S. Romanchenko, S. V. Saikova

"A set of state-of-the-art methods have been applied to study ultrafine particles and nanoscale species arising on mineral surfaces upon milling, interaction with flotation reagents, and leaching of base metal sulfide ores in order to gain insights into interfacial mechanisms. The fine fractions produced by ball milling of a Pb-Zn Gorevsky ore and four Cu-Ni sulfide ores studied with laser diffraction, dynamic light scattering, zeta-potential measurement, Xray photoelectron spectroscopy (XPS), SEM, TEM and other techniques. The particle size distributions had, aside from the peaks at 20-60 ?m, maxima near 1-2 ?m; the flotation was considerably suppressed when the yield of positively charged ultrafine particles approached tenths % (several kg per ton). High-energy XPS and X-ray absorption spectra revealed that sulfide minerals depleted in metal in air and aqueous solutions were composed of outer “polysulfide” layers, strata with disulfide species, and heavily defective underlayers, and “passivation” was explained by stability of the metal-deficit structures. Dixanthogen at pyrite and copper-activated sphalerite, dixanthogen and then cuprous xanthate on chalcopyrite, and chemisorbed xanthate at galena were specified as the main interfacial products using cryo-XPS of fast-frozen flotation slurries. The particle size, zeta-potential and behavior of colloids of Cu and Pb xanthates and dixanthogens were largely determined by the initial ratio of a cation and collector; the properties of copper xanthate nanoparticles were also affected by incorporated dixanthogen (about 15 wt.%). Submicrometer gas domains of 3-8 nm in height and “hydrophobic” forces upon the probe retraction were found on xanthate-treated minerals using atomic force microscopy and spectroscopy; their impact on flotation is briefly discussed.INTRODUCTIONInterfacial phenomena play a key role in flotation, leaching, water purification and related environmental processes. The mineral processing and extraction of metal from sulfide ores commonly involves milling the ore, which produces, along with the particles of 20 µm to 100 µm, mineral entities ranging from micrometer to submicrometer and nanometer scale. Furthermore, ultrafine particles of flotation reagents, products of metal sulfide oxidation, and so on may form spontaneously and accumulate in production water, flotation froth, deposit on mineral surfaces, affecting the flotation performance, and then enter waste waters, mine and natural drainage, polluting soils, surface- and ground waters (Miettinen et al., 2010; Wang et al., 2014). The efficiency of flotation and hydrometallurgical recovery of values, environmental issues are crucially dependent on the state of mineral surfaces. Particularly, it is generally accepted that the surface non-stoichiometry of sulfide minerals induced by oxidation and leaching should affect their hydrophobicity and reactivity, including so-called “passivation”, but the nature of such surface layers are still a matter of controversy (see, for example, Holmes and Crundwell, 2013). Another phenomenon attracting rapidly growing interest in several areas is low-dimensional gas species (“nanobubbles”) at hydrophobic surfaces that may play a decisive role in particle-bubble attachment in flotation but remains scarcely investigated up to now (Xing et al., 2017). Here, we survey our recent results on the abovementioned problems applying a series of rather new methods and approaches; more details can be found in refs. Karacharov et al., 2016; Mikhlin et al., 2015; 2016; 2016a; 2016b; 2016c; 2016d; 2017; 2017a; Vorobyev et al., 2017."

Jan 1, 2018

By Peter N. Holtham, Geoffrey J. Lyman, Matthew S. Brennan, Vijay Subramanian, Rui X. Rong, Tim Napier-Munn

Studies of the dense medium and classifying cyclone have been conducted using the Fluent computational fluid dynamics code. Experimental measurements of the segregation of medium in a DM cyclone by gamma-ray tomography and the performance of a novel classifying cyclone design have been used to test and interpret the 3D CFD predictions. The predictions of the CFD models were generally plausible, though more work is required to incorporate turbulent mixing of the slurry in the cyclone. The benefits of the novel cyclone design were explained by the model in terms of conditions favouring reduction of short-circuiting at the vortex finder, and the removal of the air core from the wall at the apex. Work is continuing.

Jan 1, 2003

By Cheng Gan, Gui Xiahui, Li Shulei, Cao Yijun, Liu Jiongtian, Wu Lun

Flotation rate constant is an essential parameter in the flotation process. The fine coal sample utilized in this investigation is anthracite from the Shenhuo mine in eastern China. Fine coal flotation rate tests were conducted to compare the flotation rate constant at constant power input with that at gradually increasing power input. Results indicate that the flotation rate constant decreases with the flotation process and increases as the flotation energy is increased. In addition, the flotation rate constant is close to the maximum value. The increasing trend of the flotation rate constant gradually slows down as the flotation energy input increases.

Jan 1, 2014

By X. L. Song

In this paper, ZrSiO4-Cd(S1-xSex) inclusion pigments were synthesized by hydrothermal method. Microstructure, morphology and properties of the powder were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared spectroscopy (IR) and CIE chromaticity, respectively. It shows that, precursors obtained at pH is about 6.0 are sol and products with higher crystallinity, red hues (a*=38.23) and inclusion ratio when hydrothermal synthesis temperature is 180? and holding time is 12h. Hydrothermal reaction mechanism was further analyzed as well. In particular, an ideal model of pigment formation was proposed.

Jan 1, 2014

By Hongchun Lou, Yan Zhang, Xianjun Lu

"The potential of Fe(NO3)3 modified attapulgite was assessed for the adsorption of phosphorous removal from aqueous solutions. Natural attapulgite was modified by Fe(NO3)3, and thus the composite adsorption materials could be obtained. Also phosphorous adsorption characterization on the iron-coated attapulgite was investigated in this research. Taken overall the results suggested that phosphorous adsorption capacity could be improved markedly by adopting ferric modified-attapulgite. The optimum phosphorous adsorption were developed in the experimental conditions of the solid-to-liquid Ratio 1g/L, the initial phosphorous concentration 5 mol•L-1, reaction time 120 min, temperature 25 ? and pH=4.0, the removal efficiency is 92.28% for the modified attapulgite. In comparison of batch experimental results of phosphorous adsorption onto natural and iron-coated attapulgite, it has provided much more likely the same change trend. On the other hand, the outcomes of this analysis indicated that ferric modified adsorbent was notably influenced by adsorption element over natural attapulgite. The Freundlich isotherm adequately described the adsorption course of phosphorous onto ferric modified-attapulgite with the correlation coefficient R2 goodness of fit of 0.9690."

Jan 1, 2014

Pure camsellite samples were prepared through crushing, sorting and grinding the high-grade iron-containing camsellite ores from Fengcheng, Liaoning, China. The flotation behaviour of camsellite was studied via a systematic investigation of camsellite flotation re-covery changes as a function of choices and dosages of collectors and depressants at different slurry pH. The results showed that at pH 8.5 to 9.5, the recovery of camsellite reached the maximum at 90%~93.5% using dodecylamine as the collector, while under the same condition a recovery of 84%~86% could be achieved with sodium oleate. The adsorption of dodecylamine was not affected by the addition of sodium hexametaphosphate, but the adsorption of sodium oleate could be significantly depressed. This implied that sodium metahexaphosphate could be used as an effective depressant for the other associated minerals during the dodecylamine flotation of camsellite. When starch was used as the depressant, the flotation of camsellite by sodium oleate was almost completely depressed in the alkaline conditions. Significant depressions were also observed when calcium chloride was added in the camsellite-sodium oleate system. The higher the slurry pH is, the stronger the depression. Zeta potential measurements indicated that the flotation was mainly initiated by the electrostatic adsorption of the collector on camsellite. X-ray photoelectron spectrometer (XPS) analysis showed that the adsorption was originated from the electrostatic attraction between the N atom in dode-cylamine and B atom in camsellite. Dodecylamine had a higher coverage on the camsellite surface than sodium oleate.

Jan 1, 2014

By Takashi Furuyama, Sukeyuki Mori, Tetsuo Ikejiri, Abel Bissombolo, Yoshitsugu Koga, Masamichi Hata

In Japan, the increasing number of automobiles newly put into circulation is followed by a larger amount of end-of-life vehicles from which valuable metals are being recovered in shredder and related plants. Nevertheless, the processing of these scrapped automobiles which has reach a recycling rate of about 75%, generates a huge volume of waste, locally known as .shredder dust., which is commonly dumped on landfills. The saturation and depletion of valuable disposal sites in the near future, as well as the social and environmental problems related to the accumulation of these residues disposals are a major challenge for the automobile shredding industry. To promote an alternative way for the management of these disposals, the authors have initiated and developed a system for their processing, on the basis that more than 90% of these residues are combustible materials that could be used as refuses derived fuel. The developed processing system points out the mechanical/physical separation of shredded automobiles residues into two streams by means of an ascending airflow passing through a vertical zigzag separator and, the compaction of the light-density fraction of materials (that is about 60% of auto shredder residue recovered as float products and mainly composed of cotton, sponges and light plastics) to form a refuse derived fuel (RDF), the density, calorific value and ignition loss of which are 1.19 g/cm3, 4470 kcal/kg and 60.7%, respectively.

Jan 1, 2003

By I. Blayda

The purpose of this work is to study and make comparative analysis of germanium extraction and related valuable components of the sublimates from the burning of domestic power coals (product 1) and germanium sulfide materials, which are a waste of lead-zinc production (product 2), by traditional chemical methods (distillation of germanium in the form of tetrachloride from raw and preliminary burning source) and by microbial bioleaching of sulfur-oxidizing bacteria. The dependence of the germanium extraction by chemical methods from phase composition of the initial raw materials was installed. The germanium tetrachloride extraction from products 1 and 2 were 78.50 and 19.52%, respectively. Such difference in indexes on extraction, is caused by germanium confinement as concomitant trace component to the basic phases to carriers. The share of acid-non-soluble compounds (tetragonal modification GeO2 and silikogermanaties) in the product 1 account for 21.5 % of germanium. Ratio between acid-soluble and acid-not -soluble germanium forms are 19.52 and 80.48 %, respectively, in the product 2. Our experiments have shown, that implementation of restorative firing (with addition of 30-40 % carbon at 1150 0?) of sulfide product 2 considerably impacted on the extraction of germanium tetrachloride (91.76 %) in comparison with its low enough extraction at straight distillation of hydrochloric acid (19.52 %). The results are confirmed by a set of physical methods. The results of processing the same so-called hard phase?s material (product 2) with the help of microorganisms are presented. It Has been established, that selected strains of bacteria are capable of extracting from initial raw materials not only macro components (iron, zinc, lead, manganese, aluminum, nickel), but also micro impurity of rare metals (gallium, germanium, zirconium). It is important that these metals were not extracted by traditional chemical methods (with application of aggressive conditions and heats) independently of the phase composition of the source. Almost complete extractions of germanium in solution using sulfur-oxidizing bacteria take place in the first day of the process independently of the phase composition of the source and the type strain. The results have practical significance and can be the basis for developing a unified biotechnological method of technogenic waste processing with a purpose of their sterilization and detoxification with simultaneous obtaining concentrates of valuable metals. Keywords: germanium, extraction, sublimates, bioleaching, sulfur-oxidizing bacteria.

Sep 1, 2012

By Tsvetan Damyanov, Nikolay Hristov, Evgeni Kostadinov, Lubomir Kuzev

"The process of grinding in drum mills is directly dependent on the dynamic forces occuring in the free movement of the grinding bodies in the volume. The subject of discussion are the potential impacts between grinding bodies having different shape and equal weight in a drum mill that has a diameter of 1200 mm. The study utilised ball grinding bodies having a diameter of 120 mm and tetraballpebs having a conditional diameter of 120 mm. The study was carried out using the Solid Works Simulation software. The following cases were examined: • Impact between two identical grinding bodies; • Impact between a grinding body and the shell surface. The study provided numerical values for impact force, kinetic energy of impact, linear speed of impact, linear displacment of the center of gravity and duration of impact deformation. The impact force of the balls is approximately 179000 N. The impact force of the tetraballpebs with typical vertices, edges and spherical surfaces depending on the area of impact is 177000 to 185000 N. Upon impact between two spherical surfaces of tetraballpebs, the contact area is 263.55 mm2, which is more than twice the contact area upon impact between two balls, which is 114.39 mm2. This determines better conditions for the transmission of kinetic energy by reducing opportunities for overgrinding."

Jan 1, 2014

By Brian Hart, Stamen Dimov

"In refractory ores, a substantial part of the gold content may be present as a sub-microscopic component within the mineral matrix of the various carriers. This type of gold may be present as finely disseminated colloidal size gold particles (<0.5µm) or as a solid solution within the sulphide mineral matrix. Such ores are not amenable to gold recovery by direct cyanidation. In order to liberate the sub-microscopic gold, the ore has to be oxidized before being subjected to gold cyanidation and extraction. Autoclave pressure oxidation (AC POX) of the sulphide ore and subsequent cyanidation is a common technology used to liberate the gold in such refractory ores. The additional presence of active carbonaceous matter in such ores (double refractory ores) represents another major obstacle for efficient gold recovery during the process of pressure oxidation and cyanidation. This carbonaceous matter (c-matter) can adversely affect the gold recovery due to its ability to adsorb, or pre-grob gold from the cyanide solution. Advanced micro-beam analytical techniques such as Dynamic Secondary Ion Mass Spectrometry (D-SIMS) and Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) have become powerful tools for characterization of different forms and carriers of gold for the needs of the mineral processing industry. Major advantages of these techniques are related to their ability to analyze individual mineral particles and provide quantitative analysis with detection limits in the low ppm/ppb concentration range. This paper describes various micro-beam techniques and procedures implemented at Surface Science Western (SSW) for quantification and characterization of the sub-microscopic gold and the preg-robbed surface gold as part of full gold deportment studies in feeds and process stream products."

Jan 1, 2014

By Gülay Bulut, Ferihan Göktepe

Pyrite is the most abundant and widespread sulphide mineral and its flotation has been investigated by many researchers. It is well known that, pyrite is floatable under acidic conditions and recovery drops with increase in alkalinity due to changes in solubility of iron hydroxides on the pyrite surface. Most of the works also revealed out that pyrite displays variable behaviour in flotation circuits. This behaviour mainly related with origin and mineralogical composition of ore, liberation size, electrochemical behavior of minerals constituting ore, the trace and minor element content of the mineral, texture, application variables belonging to flotation circuits. In this study, copper activation effect was examined on different origin of pyrites. The experiments were performed with five high grade samples of pyrite from the different mining districts of Turkey. The pyrite samples were different from each other with respect to either their physical or chemical properties; they were different physical appearances and contained different associated minerals. In the micro-flotation tests, 1x10-4 mole/L copper sulphate and 1x10-4 potassium ethyl xanthate were used as flotation reagents. First of all pyrite samples were floated using only xanthate at different pH. Results showed that best floatation results obtained at acidic pH range for all pyrite samples. When copper ions were used to activate, all pyrite samples floated at neutral and basic pH values, too but depending on the samples, recovery and pH ranges were slightly changed.

Jan 1, 2014

By Gus Van Weert, Samuel A. Bolorunduro, David B. Dreisingerm

"As deposits of high-grade base metal sulphides become depleted, attention must be focused on the treatment of complex sulphides, which contain significant fractions of precious metals such as gold and silver. Acid pressure oxidation is a promising process for these materials and the recovery of silver and gold will improve the economy of the process. Gold can be recovered from the oxidised residues, however, silver is incorporated into the jarosite specie and the cyanidation of the resulting residue yields very low recovery.Pressure oxidation of various complex sulphides was carried out at 110-150°C in sulphate media with additions of potassium iodide under conditions similar to industrial autoclaving. The resulting residues were subjected to cyanidation. High recovery of silver, up to 98%, was achieved because its incorporation into lead-hydronium jarosite during the pressure oxidation was minimised, while its deportment into the cyanide-soluble silver iodide was favoured. Silver recovery decreased slightly at high temperatures (140° and 150°C) because of the enhanced stability and kinetics of lead-hydronium jarosite, but this could be overcome by increasing acidity and iodide concentration of the autoclave slurry."

Jan 1, 2003

By Pawel Strzalkowski, Marta Baszczynska, Urszula Kazmierczak

The paper presents issues related to interference of mining activities with the environment. Exploitation of mineral resources causes primarily a modification of the landscape. All of the negative impacts on environment are short-lived and last as much as it takes to exploit the raw material. After the mine closure reclamation is necessary during which all aspects that reduce harmful effects of the mining activities on the environment must be taken into account. Current ways of reclamation allow recreating natural environment, which is different from the original and enriched in diverse new values. This requires propositions of new forms of converted land development through a detailed analysis of technical, natural, planning, economic and social sphere requirements. Before making final decisions regarding selection of direction of reclamation, a thorough analysis of the key factors has to be carried out. All steps related to the implementation of the reclamation project are shown in the paper using Limestone Mine "Górazdze" located in the south-western part of Poland as an example. This paper also presents an analysis of current ways of post-mining reclamation towards agricultural and forestry landscape, along with our own suggestion for their extension in order to preserve biodiversity. For choosing optimal solutions the most relevant criteria were considered: existing natural values and possibility of their protection. Taking into account the economic and social aspects, supported by natural potentials, implementation of tourism and recreation in this area were proposed. It was shown that this proposition would not interfere with the current trends of the natural landscaping. Finally, after completion of reclamation and land development in the considered mine area, creation of a geo-park was proposed along with appearance of geotourism in the area. To illustrate the proposed forms of post-mining land development in the form of maps, an ArcGIS(ESRI) software was used.

Jan 1, 2014

By Aubrey Mainza, Malcolm S. Powell

"A hydrocyclone with two vortex finders, named the three-product cyclone, has been successfully tested in the Platinum industry for dealing with the dense chromite found in UG2 ores. This dense component preferentially reports to the cyclone underflow, resulting in an over-ground fine chromite component in the final product. The dense media effect caused by a high chromite concentration in the cyclone feed produces a coarsening of the cyclone overflow, which results in loss of recovery through over-size material in the float feed. The fine barren particles of chromite that report to the overflow are recovered through entrainment in the flotation process, resulting in detrimental contamination of the slag produced from the concentrate.With the three-product cyclone a middlings product has been extracted that has a higher concentration of fine chromite. This volumetric stream flow represents a small percentage of the total cyclone feed and it is thus possible to treat it separately via fine screening to remove the fine chromite from the system and recover coarse silica."

Jan 1, 2003