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By Masaki Kitazume, Yoshiaki Kikuchi

"Abstract Pile foundation is one of fundamental techniques to improve the bearing capacity and settlement characteristics of superstructures. Wide varieties of piles having various shape, size and material were developed and have been applied to a lot of construction projects throughout the world. The deep mixing method, an in-situ admixture stabilization method, was developed in 1970s in Japan and the European countries, and has been frequently applied to many construction projects for various improvement purposes such as increasing bearing capacity and horizontal resistance, reducing ground settlement, preventing liquefaction and so on. The design methods, execution procedure and quality control and assurance (QC/QA) of the method are standardized or specified in many countries. These standards, specification and/or technical manual have been a remarkable contribution to spread the techniques throughout the world. The QC/QA is one of the major concerns for clients and engineers who have poor or no experience of the technologies. In order to assure the high quality of deep mixing work in the global market, it is necessary to establish the concept of QC/QA and correlate the output of different procedures. Upon the request by the organizing committee of the DFI-EFFC International Conference on Piling & Deep Foundations, the authors conducted survey of the specifications and standards on the piling and deep mixing technologies in Asian countries. In this manuscript, the results of survey are briefly introduced by comparing these specifications and standards.IntroductionThe pile foundation is one of fundamental techniques to improve the bearing capacity and settlement characteristics of superstructures. Wide varieties of piles having various shape, size and material were developed and have been applied to a lot of construction projects throughout the world. The design method, execution procedure and quality control and assurance of pile foundations are standardized in many countries based on the accumulate research results, laboratory and field experiences. In Japan, steel pipe piles are mainly constructed by hammer driven in port construction. On the other hand, precast pre-stressed concrete piles or cast-in-place piles are mainly used in on land construction. When precast pre-stressed concrete piles are constructed, piles are usually set by inner excavation method because of preventing noise and vibration problems. More than 50 years ago, noise and vibration problems had not been serious problem in Japan, but around 50 years ago, they became serious and now less noise and vibration construction methods are used for pile construction on land in Japan. In Asian countries, though piles used for construction have a lot of variety, precast pre-stressed piles are commonly used. In this report, execution controls of construction methods of steel pipe piles and precast concrete piles are mainly considered."

Jan 1, 2014

By L. Kuzev

Unknown and unpopular vibrational grinding mills possibilities to horizontal working chambers have been discussed. They can be realized under normal conditions with the typical values of vibrations applied with vibrational grinding which are: vibration frequency from 15 Hz to 50 Hz, vibration amplitude to 6 mm and vibration geometry. These possibilities constantly increase involving new raw materials and processes. Vibration grinding is possible with other technological process accompanied by intensified technological processing, while the process decreases. In many cases these technological decisions are original.

Jan 1, 2014

By Fatemeh Saeidi, Malcolm S. Powell, Mohsen Yahyaei

In order to deal with the problems of existing comminution models a new approach towards the development of mechanistic models has been made so as to better understand the physics of milling processes and environments. Despite enormous improvement in this field a comprehensive study of rock breakage characterisation, appropriate for use in these types of models, is still scarce. This paper reviews the existing models of comminution according to ore characterisation techniques and parameters. The authors have looked into the existing testing methods and their applied mechanisms of breakage, using standard test results available at the JKMRC. The study includes classifying testing devices such as the drop weight tester, rotary breakage tester, slow compression, and piston and die based on the few major fundamental mechanisms of breakage that are experienced by rocks in the breakage process. The paper compares the range of particle size and energy utilisation, applied strain rates and loading mechanisms for the equipment. The product size distributions from the various equipment is compared for equivalent input energies, various loading rates but the same level of energy intensity, a broad range of energy including low energy utilisation and fines generation rate for equivalent specific energy input. The results clearly show that the outcomes and conclusions on competence and energy for breakage are a function of the test method that is applied. In ongoing work, it is proposed to investigate common tests that can be applied to characterising ores in a manner suited to modelling a range of comminution devices.

Jan 1, 2014

By Roberto Galery, Priscila Esteves, Braz Cardoso, Marcelo Stopa

"It was developed in this work a computational tool to aid in anomaly detection present in the operation of ball mills. The tool uses a torque estimator that is based on measurements taken exclusively in the drive motor. The ball mill equipment widely used in the mining industry has, inherent to its principle of operation, high energy consumption and low efficiency. These characteristics are accentuated when the mill operates outside the ideal conditions of velocity and loading. Direct measurement of these variables is extremely difficult because it requires the installation of sensors in moving parts of the mill. Thus, systems that can help monitoring the operating conditions and predict anomalies are useful because they contribute to improving the performance of the process, help to reduce the energetic consumption, wear on the mill surface and frequency of maintenance shutdowns. The detection strategy implemented in this work is based on the fact that operational anomalies such as an inadequate percentage of balls and incorrect angular velocity manifest itself as a change in spectral components of the torque signal in the mill driven by an electric motor. The mill torque was estimated by processing motor variables measured by sensors commonly used for control purpose and installed exclusively in the motor. The mill was operated at various fault operating conditions and signals from electric motor and vibration on the mill shaft were measured. The spectral components present in the estimated torque signal were then compared with signals from a vibration sensor in order to establishing a correlation with anomalous operation condition of the mill. The experimental results showed that the signals obtained has an excellent correlation with other variables obtained by direct measurement and have potential to be used to construct a system for automatic fault detection in the operation of ball mills."

Jan 1, 2014

By Adam Powell, Salvador Barriga, Matthew Earlam

"The inert anode is a key enabling technology for dramatic energy and emissions reduction in extractive metallurgy. In molten salts, the materials challenge is nearly insurmountable: the anode must conduct electrons at high temperature in a pure oxygen and molten salt environment. A solid electrolyte, e.g. zirconia, between the salt and anode removes the molten salt stability constraint, and can act as a container for a liquid metal anode. This can be liquid silver for oxygen-generating inert anodes, or several metals for natural gas-fueled anodes; it is possible to switch between these modes. The solid electrolyte brings several other benefits: it eliminates molten salt contamination of the anode gas, creates a reducing environment enabling low-cost steel vessels, increases current efficiency, and eliminates carbon contamination of the product. New developments presented here, including current collector and low-cost anode designs, amplify these benefits for producing aluminum, magnesium, rare-earths, and other metals.IntroductionReactive metals such as magnesium, aluminum and rare-earths play increasing roles in efficient transportation and clean energy. In response to new fuel economy standards, automotive OEMs are planning large increases in use of aluminum and magnesium to reduce vehicle weight. Rareearth permanent magnet motors and generators exhibit better power-to-weight and efficiency than induction motors and other designs, making this today's primary motor technology for hybrid and electric vehicles, and for wind turbines. Nickel metal hydride (NiMH) batteries with lanthanum are dominant in hybrids. In 2011, transportation comprised 28.6 out of 103.1 EJ of US energy consumption [1] and 1,845 out of 5,471 million metric tonnes (MMT = 109 kg) CO2e of US greenhouse gas (GHG) emissions [1], creating big targets for economy-wide reductions.Unfortunately processes for making reactive metals for these applications are very inefficient and heavily-polluting. In primary aluminum production, Hall-Heroult cell electricity use [2] is more than double the reaction enthalpy due to heat losses through frozen cryolite side-walls and anode gases, graphite anode plants add significant energy use and GHG emissions [2] (see Table 1). Magnesium is even worse: silicothermic reduction by the Pidgeon process in China produces about 85% of the world's magnesium using coal or coke gas [3]. Chloride electrolysis begins with high-purity MgO and requires carbochlorination or hydrochlorination and costly chloride dehydration [4]—rendered unnecessary for aluminum by the Hall-Heroult cell. Production of neodymium and lanthanum with graphite anodes leads to inconsistent carbon content: small cells make 1 kg batches for analysis, sorting and sale by carbon content, with very high labor and analysis costs. And vertical electrodes give no incentive to reduce anode effect: some reports indicate that China's rare-earth metal industry emits more CF4 and C2F6—with global warming potential (GWP) 6500 and 9200 times CO2 respectively—than China's aluminum industry [5]."

Jan 1, 2014

By P. A. Crane, N. Shirley, Aung Moe, H. M. Nicholson, D. Kan

Kazakhstan’s first commercial copper-leach solvent extraction-electrowinning plant, Central Asia Metals’ Kounrad project, was commissioned in April 2012. Exploiting low grade waste stockpiles produced during Soviet era open pit mining, a 10,000 tpa copper cathode plant was designed, constructed and commissioned within 18 months. Overcoming initial challenges with a workforce unfamiliar with the technology and with extensive periods of sub-zero conditions during winter the project has consistently met targets and produced high quality copper cathodes at cash costs of less than US$1/lb. Challenges encountered during the first two years of operation are described and future plans briefly discussed.

Jan 1, 2014

By Zuhair Ibrahim, Dan Tillema, Ali Reza

This paper details the investigation of a fatal explosion that occurred on April 8, 2011 at a magazine used to store fireworks in Waikele, HI. The fireworks had been confiscated by the Bureau of Immigrations and Customs Enforcement after they were informed that a container shipped to the United States contained illegal fireworks. Four groups of cardboard cartons that were marked as 1.4G (consumer fireworks) were determined to be consistent with the more explosive 1.3G type, commercial display fireworks. The subcontractor retained to destroy these fireworks stored the shipment in the subject magazine and was in the process of disassembling them on the day the explosion occurred.

Jan 1, 2014

By M. Karamoozian

Modelling and optimisation of the power draw of large SAG mills are important due to the large power draw which modern mills require (5~10 MW). The cost of grinding is the single biggest cost within the entire process of mineral processing. Traditionally, modelling of the mill power draw has been done using empirical models. Although these models are reliable, they cannot model mills and operating conditions, which are not within the model database boundaries. Also, due to their static nature, the impact of the changing conditions on the power draw, within the mill, cannot be deter-mined using such models. Despite advances in computing power, on-line modelling of large plant scale mills could be a time consuming task. On the other hand, using on-line parameters for model-ling, result in more reliable control of SAG mill without performing any more costly tests. In this paper, SAG mill power draw is modelled using neural network approach. Six inputs, namely: solid percent, two bearing pressures, noise, recycle and feed rate were used to model the power draw. The produced model shows an acceptable correlation coefficient, R2 =0.9623.

Jan 1, 2014

By C. Guney Olgun, Fleur Loveridge, Tracy Brettmann, William Powrie

"Abstract Deep foundations are increasingly being used, not just to carry structural loads, but also to act as heat exchangers as part of a ground source heat pump system. Such foundations, often called energy piles, have the potential to make significant contributions towards meeting the heating and cooling demands of buildings, thus reducing the overall energy consumption and carbon dioxide emissions during their lifespan. To ensure that the available energy from these systems is maximized, it is important to determine the thermal conductivity of the surrounding soils, a key design input parameter. In situ thermal response tests are commonly used to carry out this task for small diameter borehole heat exchangers. However, there has been debate over the applicability of these tests to energy piles due to their larger diameter and the consequent increased influence of the pile thermal properties on the test outcome. This paper examines the results of three thermal response tests carried out on piles of different diameters and thermal properties installed at the same site in Texas. Transient analysis of the test results, combined with comparisons to laboratory testing of soil samples from the site, is used to given an indication of the applicability of the thermal response test over different timescales for the different piles. It is concluded that the test is most suited to smaller diameter piles constructed with lower thermal diffusivity materials. Recommendations are given for the conduction of pile thermal response tests and interpretation of test data.INTRODUCTIONAs issues of energy security and scarcity become more important, the use of ground source heat pumps to provide renewable and sustainable heating and cooling to buildings is set to increase. Traditionally such systems use special purpose ground heat exchangers to extract and/or inject heat from/into the ground. The heat exchangers comprise a series of plastic pipes cast into the ground and then connected to the heat pump via a series of header pipes. In the case of building space heating, the heat pump then steps up the temperature difference to deliver the extracted heat at a useable level. However, financial and carbon savings can result by utilizing the building foundations as heat exchangers as well as to carry the building structural loads.Piles, often termed “energy piles”, are the most common type of foundation heat exchanger, and their construction has been increasing in recent years (Amis et al, 2009). However, while energy piles have the potential to make significant contributions towards meeting building heating and cooling demands, there remains scope for improving their thermal efficiency through improved analysis approaches (e.g. Loveridge & Powrie, 2013). In fact the greater diameter of many energy piles means they have the potential to deliver increased short term thermal energy storage compared to more commonly installed borehole heat exchangers."

Jan 1, 2014

By S. Groudev

Acid drainage waters generated in the uranium deposit Curilo, Bulgaria, were treated by means of a pilot-scale passive system consisting of a permeable reactive multibarrier and a constructed wetland connected in a series. The multibarrier had a total volume of 23 m3 and consisted of an alkalizing limestone drain and an anoxic section for microbial dissimilatory sulphate reduction, bio-sorption and additional chemical neutralization. The waters had a pH in the range of about 2.5 ~ 4.0 and contained radionuclides (uranium, radium), heavy metals (copper, zinc, cadmium, lead, nickel, cobalt, iron, manganese), arsenic and sulphates in concentrations usually much higher than the relevant permissible levels for waters intended for use in agriculture and/or industry. The water flow rate through the multibarrier varied in the range of about 1 ~ 17 m3/24 h, reflecting water residence times of about 300 ~ 18 hours. An efficient removal of pollutants was achieved by the multibarrier during different climatic seasons, even during cold winter days at external air and water temperatures close to 0oC. The multibarrier effluents were enriched in dissolved organic compounds and in some cases still contained manganese and iron in concentrations higher than the relevant permissible levels. These pollutants were removed in the constructed wetland as a result of the activity of different heterotrophic microorganisms, including some bacteria able to oxidize the bivalent manganese and iron ions to Mn4+ and Fe3+, respectively.

Jan 1, 2014

By Qiuyang Hong, Bo Li, Dongyun Liang

"A weathering-crust niobium-rare earth-bearing deposit is formed by the weathering alterationof alkaline granite, which is refractory due to its low grade and complex properties. The mineralogicalcomposition of ore, the grain size of majorminerals as well as the occurrence of Nb and REE are studied in this paper using MLA combined with traditional methods. According to the results, a wide range of Nb-Ti-REE compound minerals including titanoniobite, uranpyrochlore, chlopinite, samarskite and ilmenorutile areformed for the extensive isomorphous substitution among the elements of Nb, Ta, REE, Fe, Ti, U and Th. The occurrence of REE is extremely complex. First, the REEexistingas rare earth minerals including monazite, xenotime, bastnaesite,etcaccount for 21%. Second, the REEexist in the lattice of Nb and Zr minerals as isomorphous additions, which account for 18%. Third, the REE exist as colloidal rare earthdeposit,which account for 35%. Last, the REEexistingas ion-adsorption-type rare earth,which are adsorbedon the kaolinite in the form of hydrated hydroxyl ions, account for 26%.Based on the results of mineralogy, the combined technology process "mineral processing- hydrometallurgical separation" is needed to deal with the ore. The mineral processing tests show that, for the feed ore containing Nb2O5 0.065%, REO 0.13%, an Nb-REE concentrate containing Nb2O5 1.38%, REO 1.98% can be gained by "high intensity magnetic separation-regrinding-gravity separation by shaking tables". The recovery of Nb2O5 and REO is 62.42% and 44.78% respectively. The Nb-REE concentrate is dealt by the metallurgy process "direct reduction- acid leaching & acidulating- neutralization & precipitation- chlorination & distillation" and the rare earth oxide of 92.34% REO as well as the Nb-Zr oxide of 24.62% Nb2O5 can be obtained with the recovery of REO and Nb2O5 being 76.83% and 59.37% respectively."

Jan 1, 2014

By D. Szyszka

During passing gas bubbles through mineral suspensions, some mechanical carryover of fine particles to the froth layer always takes place. The entrainment of mineral particles is influenced by many parameters, mostly by the particle size and the concentration of the frother. The paper deals with influence of selected frothers (methylisobutylcarbinol (MIBC), a-terpineol, and hexadecane tricosaethyleneglycol ether (C16E23)), common laboratory flotation frothers, on the mechanical car-ryover of quartz, a typical gangue mineral component of ores. Entrainment tests were carried out in a laboratory Mechanobr flotation machine with quartz particles suspended in aqueous frother solu-tions. The mechanical recovery of quartz in the presence frother was increasing with time and reached plateau after about 20 minutes of flotation. The plateau level of quartz recovery depended on the frother concentration. Initially an increase of the plateau with frother concentration was observed until the plateau reached the highest level called the maximum recovery emax. The emax can be used as a parameter to characterize the ability of frothers to entrainment. In the studied quartz-frother flotation system the maximum entrainment was 32%, 50% and 80% for methylisobu-tylcarbinol (MIBC), a-terpineol, and monohexadecane tricosaethylene glycol ether (C16E23), re-spectively. A comparison of the maximum entrainment factor emax with other, known from literature, indices such as bubble critical coalescence concentration (CCC), dynamic foamability index (DFI), Jw, e =25%revealed, except DFI, their similarity.

Jan 1, 2014

By G. F. Zhang

Yunnan mineral is a kind of containing Ta-Nb rare earth deposit, the most potential economic valuable element in it is Sc, and raw mineral has 17.0 g/t Sc. Take the character of Sc into account, the key problem in producing scandium chloride molten salt by adaptive technology is how to man-ufacturer anhydrous scandium chloride molten salt. During the course above, the key problem is that preventing Scandium chloride from being hy-drolyzed into ScOCl. The ScOCl content of molten salt not only affect purifying scandium but al-so do harm to the production of Mg-Al alloy. In order to restrain the creation of ScOCl, add ammo-nium chloride into molten salt. As long as ScOCl is created, it would be chloridized. Thus, during the course of dehydrating anhydrous chloride molten salt this method prevents scandium from hydrolyzing. Accordingly, the key phase of this producing course is eliminate ammonium chloride and the surplus crystal water, and the most crucial of it is restrain scandium chloride from being hydrolyzed into ScOCl. This research analyzed the theory that ammonium chloride is trend to be hydrolyzed into ammo-nium chloride, and propose the research scheme of restraining this process from creating ScOCl. The new process of restraining the generating of ScOCl and dehydration for crystal water rare earth chloride is adopted: Inert gas temperature increases rapidly to a certain degree to eliminate ammonium chloride and crystal water. The experimental research were done such as : the temperature of eliminating ammonium chloride and crystal water, amount of ammonium chloride, time, temperature growth speed, influence of inert gas flow toward to scandium percent hydrolysis, whereby, we conclude the optimal process condition in this period: Temperature: 400°C, proportion of oxidized scandium and ammonium chloride is 1:1.5(Proportion of oxidized scandium and additional salt is 1:5.4), time is 120minute, temperature growth speed is 10?/min inert gas flow is 5L/min.

Jan 1, 2014

By Y. Nakamura, T. H. Okabe, S. A. Sunkar, K. Nose

Ruthenium (Ru) is known as a platinum group element with a very small production volume. In fact, the worldwide annual production of primary Ru metal is only about 20-30 tons, and it depends on the amount of Pt produced, since Ru is a byproduct from Pt smelting. The primary uses of Ru are as a material for resistors, as a catalyst for electrode materials, and as a sputtering target for hard disk memory storage. In order to recover Ru from the spent sand-blasting abrasive media generated during the cleaning of the apparatus used for Ru sputtering, a hydrometallurgical recovery process using hypochlorite solution has been investigated. In this study, various types of recycling processes that are presently under development are also introduced, and their features and differences are discussed. The advantages and disadvantages of the new recycling processes are evaluated, and the possibility of establishing new recycling processes in the future is discussed from a multilateral perspective.

Jan 1, 2014

By G. Jenny

The particle size distribution of ground minerals is of decisive importance for downstream processes like floatation, separation, drying or others. In order to optimize the process efficiency on one hand and the final product quality on the other hand an early control of the grinding or classification stage is essential. The ultrasound based particle size analyser OPUS is capable of performing on-line particle size distribution (PSD) and solid content measurement of mineral slurries such as iron ore, copper ore, fluorspar, or quartz sand and alumina directly in heavy and rough process environment. The instrument provides a PSD of 31 size classes and can be applied for particles from nanometer range up to several millimetres. Arbitrary interpolations in between the 31 measured points are available. Typical residue values show an excellent agreement to off-line particle size analysis methods such as e.g. sieve analyses or laser diffraction. OPUS is designed as rugged in-line probe made from stainless steel. The applied technique is independent of product flow dynamics, contamination, optical properties, vibrations, pressures or changes in solid concentrations. The instrument provides all data on the system?s PC or on the process control system by a variety of interfaces.

Jan 1, 2014

By N. Aslin, R. Clark, G. Heferen

The methods of harvesting copper from stainless steel mother plates has been investigated from fundamental and operational experience perspectives. At least five different harvesting techniques have been identified that have different effects on product quality, current efficiency, current distribution, growth morphology and ease of stripping. Each method is examined from fundamental principles to understand what occurs during the harvesting process and why the particular effects are manifested. Experience from plants operating the harvesting method is provided to show that the fundamental understanding is relevant. Best practice harvesting method and harvesting management are described.

Jan 1, 2014

By Yuanyuan Wang, Yuhao Ding, Hao Bai, Kang Zhou, Guangwei Du

"In this paper, the list analysis of GHG emissions of aluminum industry was conducted based on the data from typical electrolytic aluminum plants of a China’s northwest province. The results show that under the conditions of average anode effect coefficient as 0.16 times/(cell• day) and anode duration as 5 minutes per day, equivalent emissions of CO2 reached 1.23 ton per ton of aluminum, in which PFC emissions accounted for about 71%. Compared with foreign advanced level, which is 0.87 ton per ton of aluminum under the conditions of average anode effect coefficient as 0.01 times/(cell•day) and anode duration as 0.46 minutes per day, there is much room for China’s aluminum industry to reduce GHG emissions. Since anode effect plays an important role on PFCs generation in electrolytic aluminum process, how to control anode effect strictly becomes the key factor for remarkable reduction of GHG emissions in China’s aluminum industry.IntroductionTechnology of aluminum electrolysis is a mature and efficient process of aluminum production. Due to the huge demand on aluminum worldwide, so resource consumption, energy consumption and pollutant emissions in the process of aluminum production are still large. The global output of aluminum reached 45193 kt in 2012. A large amount of CO2 and PFCs are produced in the process of aluminum production, and the greenhouse effect and environmental pollution caused by emissions of them is a concern. PFCs belong to a powerful greenhouse gas, thus emission reduction of PFCs is very important for aluminum electrolysis industry. At present, China's aluminum production accounts for about 33% of the world's aluminum production, and controlling PFCs emission has become the key point of pollution control of aluminum electrolysis industry in China [1].Taking the case of a typical electrolytic aluminum plant of a China’s northwest province, this paper studies the list analysis of GHG emissions of aluminum industry in China. GHG emissions of a China’s northwest province were calculated through investigating existing situation of aluminum electrolysis industry in the province, knowing capacity, output, main production technology and equipment level of aluminum electrolysis industry, and using the calculation framework and methods of GHG emissions of aluminum electrolysis industry, which were put forward by the intergovernmental panel on climate change (IPCC), the international aluminum association and other organizations at home and abroad. The list analysis of GHG emissions of aluminum electrolysis industry will offer useful information in promoting emission reduction of GHG in aluminum electrolysis industry, improve the efficiency of energy utilization."

Jan 1, 2014

By Andy L. Shaffer

A novel liquid settlement system (LSS) was installed in advance of mining at a western United States (U.S.) longwall mine to measure total roof sag from the time of cutting to days after mining during gate road development. The system was used to compare differences in roof sag between conventional place-change mining using a Joy continuous miner and a Fletcher roof bolter and mining using a miner-bolter. The LSS was installed with an intrinsically safe, miniature data acquisition system (MIDAS) to record roof response at four locations in the same gate road. The system utilized pressure transducers to measure roof sag by the principle of falling head (fluid pressure) in fluid-filletubes installed in the immediate roof. Details of the LSS design, installation, data collection, post-processing, and future applications are discussed.

Jan 1, 2014

By N. Nehoroshev, P. Solozhenkin, N. Voyloshnikova, A. Pshennikov

"Molecular modeling of clusters of major bismuth minerals, Bi2S3, was carried out whereby molecular models of minerals and reagents clusters were created. Their HOMO and LUMO energy levels were calculated and using known modelling equations, the absolute hardness ?, eV and electronegativity were calculated. The charges of separate atoms of clusters and the change of properties of the minerals were determined which allowed predictions of the flotation properties of raw ores containing rare bismuth minerals. Modeled complexes containing the clusters of minerals and various collectors were constructed, consisting of atoms and bonds within clusters of minerals. Major physical and chemical parameters were determined for the complexes created, including the total and electronic energy. Based on the energy calculations, predictions of the collector efficiency were proposed. The efficiency of collector was established for various thiolic reagents, the compounds of phosphorus (III) and mixtures of reagents. Theoretical results were checked and confirmed against laboratory ore flotation tests. A gold-bismuth-magnetite ore type was studied where gold, bismuth and iron (magnetite) are of industrial interest. The ore contains 2.8 g/t Au, 1.0 g/t Ag, 0.26% Bi, 45% Fe and 1.25% As. Sulphide mineralization can be mainly found in the form of pyrrhotite, pyrite and arsenopyrite. Bismuth can be mainly found in the form of bismuthite and native bismuth. Gold is fine. A flow sheet for Zhelezny Kryazh ore treatment was proposed. This flow sheet consists of grinding to 95-98% -74 µm, sulfide flotation with two cleaner with xanthate addition, cyanidation of flotation concentrate and flotation tailings included treatment with with CaO (6 kg, 6 hours), cyanidation (8 hours) and CIL (8+24 hours). Saleable products are gold doré, bismuth and iron concentrate."

Jan 1, 2014

By Vladimir Vigdergauz, Sergey Kondratiev

The paper reviews the existing criteria of the formation of particle-bubble aggregates during flotation. It is shown that predictions obtained by these criteria do not completely fit to the interaction between mineral particles and air bubbles. Experimental results of the studies into the influence exerted by molecular forms of collectors on the particle-bubble interaction are reported. Rate of dry spot expansion on the surface of pyrite with various combinations of chemically and physically adsorbed xanthate are examined. It is shown that molecular forms of collectors accelerate the rate of dry spot expansion on the mineral surface after the local rupture of the water film between particle and air bubble. The authors come to a conclusion that the molecular forms of collectors remove water from the interlayer between mineral particle and air bubble during their contact. Similarities of the proposed mechanism with the action of ion-molecular associates of fatty acids and amines are discussed. Reagents with high surface pressure and rate of spreading at the water-bubble interface are required for the effective interfacial dewatering. It is concluded that the value of surface pressure can serve as the criterion for efficiency of physically adsorbed reagents. The low surface pressure indicates weak collecting ability but high selectivity of the collector. Therefore, the presence of the molecular forms of collectors in the sorption layer is the necessary condition for formation of particle-bubble aggregates, and comparison of the surface tensions of collectors could be recommended as the estimation criterion of their flotation activity and selectivity.

Jan 1, 2014