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By Dong Liang, Qijie Zhai, Zhichen Zhang, Qixin Li, Zhishuai Xu

"The formation, distribution and survival of pure Al nuclei under surface pulsed magneto oscillation (SPMO) treatment were investigated with thecombination of experiments and numerical simulation. The results indicated that the nuclei originated from the whole top surface of melt owing to the oscillation of top surface induced by SPMO. The temperature field significantly affected the survival of the nuclei The electromagnetic force and flow field of the melt with SPMO treatment were simulated by finite element software ANSYS. The electromagnetic force mainly distributed below the top surface near the mould wall. The electromagnetic farce not only made the melt oscillate but also increased the convection of meh below the top surface vigorously. The oscillation near the top surface of the melt promoted the nucleation largely, and the convection increased the uniform of the temperature distribution in the whole meh which favored the survival of nucleiIntroductionAs we all know, fine equiaxed grains are beneficial fur the improvement of the mechanical property, process ability and the uniformity of metallic materials [1-2]. With the researches of recent decades, people discovered that the electromagnetic field is an efficient method to refine the solidified structure of metals [3-7]. Pulsed magnetic field technology obtains more and more attentions in recent years due to its smaller power consumption, bigger instantaneous magnetic field intensity, non-contacting with the meh and simple convenient equipment manufacturing [8-9]. However, the melts would splash fiercely when pulsed magnetic field is applied with a slightly higher power. Thus, based on the understanding of the solidification refinement mechanism of electric current pulse (ECP) [10], Gong et al [11] developed a novel technology called pulse magneto-oscillation (PMO) to refine the solidification structure. The technology can be easily applied in the solidification structure refinement of continuous casting slab. But fur aluminum continuous casting, the sump is very shallow, which greatly limits the application of pulse magneto-oscillation technology."

Jan 1, 2014

By L. L. Chasko, D. W. Alexander

Los investigadores del National Institute for Occupational Safety and Health’s Office of Mine Safety and Health Research han evaluado los efectos que la malla de control de suelos podría tener en la distribución de polvo flotante de roca y carbón en minas de carbón. El creciente uso de mallas para controlar el desconchado o caída de material del techo y las vigas introduce superficies elevadas adicionales para recolectar el polvo de roca o de carbón. Es posible que el potencial para la propagación de explosión del polvo se incremente si el polvo flotante de carbón no es convertido en inerte de manera adecuada. Adicionalmente, la malla podría interferir con la recolección de muestras representativas de polvo cuando se usa el método de recipiente y brocha desarrollado por la U.S. Bureau of Mines y usada por la Mine Safety and Health Administration para muestreo de banda. Este estudia hace una estimación del polvo de roca o carbón adicional que pudiera acumularse en la malla y desarrolla un método para recolectar muestras de polvo representativas atrapado en las mallas.

Jan 1, 2014

By K. Hori

In this study, the determination of optimal conditions for jig separation has been investigated with a TACUB jig separator. The TACUB jig, from which a Batac jig originated, is a useful gravity separator that is effective to separate crushed solid wastes as well as coarse ores. A mixture of crushed polyethylene (specific gravity 1.3) and polyvinyl chloride (specific gravity 1.5) was separated by a batch TACUB jig by varying the frequency (wavelength) and the amplitude (pulse stroke length). It was found that the sample particle layer in the separation chamber was fluidized without turbulence by the rising water pulse resulting in the separation. However, a too strong water pulse reduced the efficiency of the separation of the particles. The results indicate that the specific velocity of the rising water is necessary to fluidize the particle layer without turbulence to separate the particles. The expansion ratios of the thickness of the particle layer in rising flows were measured in a cylindrical column. The pressure losses by the particle layer were calculated from the expansion ratios and the velocity of the rising flows by Ergun?s equation. The curve of the pressure loss vs. the velocity of rising flow showed a maximum point corresponded to the point of fluidization. The velocity of a rising flow on the point of fluidization provided the optimal separation condition.

Jan 1, 2014

By A. Norori-McCormac

"Air recovery, the fraction of air entering a flotation cell that overflows the cell lip, is linked to flotation performance, and it has been shown through industrial testwork that operating flotation cells at air rates that yield the Peak Air Recovery (PAR) results in high mineral recovery. For operating parameters over which flotation plants have little control, such as particle size, investigating the effect on the position of PAR, and the subsequent effect on flotation performance, proves more challenging. To this end, we have developed a bench scale flotation system that runs continuously and exhibits froth behavior similar to that found industrially, allowing the study of such parameters as particle size in addition to air rate. The bench scale system comprises a 4 l baffled cylindrical flotation cell, stirred by a Rushton impeller. The concentrate is recycled back into the pulp, allowing for continuous operation. Glass beads are used as solid particles, allowing a wide range of particle sizes to be tested, with TTAB as collector and MIBC as frother. The system allows operation at air rates typical of industrial flotation systems (1 -2 cms-1 superficial gas velocity), in addition to yielding a froth that coalesces and bursts and exhibits a peak in air recovery as cell air rate in increased. Solids and water recovery is also measured. The results show that air recovery is sensitive to changes in particle size. The intermediate size distribution showed a peak in air recovery (PAR) that corresponded with the maximum solids flowrate, as found industrially. It is shown that finer particles do result in more stable froths and higher recoveries, particularly at low air rates. The effect of particle size on the position of PAR is not yet unequivocally determined from these results."

Jan 1, 2014

By Y. G. Sun

This paper mainly reported separation manganese silver oxidized ores process by amylum de-gradation reduction and its influencing factors. When dosage is given according to nMn : nH2SO4 : n(C6H10O5)n : nH2O=1:k21.8: k116.66:30, the amount of up to 95.93% Mn leach rate and less than 2% silver loss can be obtained. Cyanidation process was used to extracted silver from leaching Mn residues. Silver leach rate could reach 94.15% at consumed amount of 1kg/t NaCN for 1h. Silver leach recovery rate was more than 92.27% by leaching Mn and cyanidation two-step processes so manganese and silver were separated effectively.

Jan 1, 2014

By M. Kinnunen

Handling of municipal solid waste (MSW) and control of its potential resources is becoming increasingly important in modern society. The OECD (Organization for Economic Co-operation and Development) average on municipal waste produced in 2003 was that of around 570 kg per inhabitant. In European Union countries around half amount is of MSW landfilled. In Finland still 88% of MSW was landfilled in 2004. Since incineration reduces MSW volume significantly while producing heat energy, it has become one of the most common waste handling techniques. The shortcoming of incineration is however, that incinerated MSW is often not pre-sorted and it produces slags and ashes as side streams from which recovery of metals is difficult. This paper looks into possibilities of scrap metal recovery for recycling from municipal solid waste incineration (MSWI) bottom ash. In order to do that, a flow sheet of physical separation methods was developed and tested with Finnish rotary furnace MSWI bottom ash. In addition, an empirical model for estimation of the recoveries of scrap metals with physical separation methods for treatment of MSWI bottom ash was developed. According to the results of this study, for 1 Mt of incinerated MSW with 30% mass reduction, a minimum resource potential of 100 kt for magnetic metal scrap of roughly 24 % grade and about 19 kt of non-magnetic metal scrap of roughly 65 % grade. In other words, 57 kg magnetic scrap and 12 kg non-magnetic scrap per inhabitant at the mentioned grades, respectively. Although wide variations of parameters affect the MSWI bottom ash quality, it can be said that a considerable amount of metals is drained into MSWI bottom ash. Results of this study show that from MSWI bottom ash significant material streams metal scrap can be reintroduced into the resource cycle which would otherwise be lost.

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 L. X. Zhang

It is very important to improve the A/S of the bauxite to keep sustaining development of Chinese alumina industry. This article summarized the issues of several desilication technologies, which are named as normal flotation, reverse flotation and bi-flotation. Normal flotation has been got industrialization because of technologic advantages. The campaign experiment of reverse flotation which has principle advantage was carried out in 2004, and bi-flotation which is combined the advantages of both the normal flotation & reverse flotation has the most attractive future. The development of bauxite flotation will be focused on multi-utilization of bauxite by mineral process technology and corresponding equipment which satisfied with the flotation technology and reagent.

Jan 1, 2014

By M. K. G. Vermaak

Kimberlite weathering has been a topic of ongoing research within De Beers for many years. Using kimberlite weathering as an alternative to crushing has many advantages e.g. power and reducing diamond breakage. Weathering could also possibly be used in conjunction with crushing just to weaken the material and reduce power consumption. These forces have driven current research to investigate whether kimberlite weathering could be utilised for these reasons. Weathering in this context does not refer to weathering over long period of time but rather to disintegration of the material in aqeous media in relative short time periods. Previous published work discussed that the presence of smectite renders kimberlite weatherable and that the amount of smectite determines the rate of weathering (Morkel and Vermaak, 2006). The current work investigates whether cation ex-change or the adsorption of organic species in the smectite interlayer could influence the observed weathering behaviour. The results show that cation exchange does take place in the presence of cation species and that the weathering behaviour can be drastically improved with especially Cu2+ cations. Concentration and time effects of the weathering was also investigated. Weathering tests with organic species such as ethanol, methanol, edta, pentanol, butanol, acetic acid and oxalic acid was performed. The results show that organic species does improve weathering but under these testing conditions was not as effective as cations.

Jan 1, 2014

By H. Mengbing, A. Potokin, A. Usov

"Revealed and analyzed in the study are the ways of significant perfection of specific characteristics of the equipment, such as use of high-frequency voltage transformation to create a charger; use of pulse transformers, with core made of materials with high magnetic permeability, in pulse generating circuits; as well as use of special ways to produce voltage pulses with a short front. The experiments have proved the possibility to adapt these technological solutions for electric-pulse installations, and suggested on this base is a strategy of further development and application of electric-pulse technologies. The different applications joint work schemes of voltage sources with two levels voltage and energy in electric pulse technologies are investigated. The possibility of increasing energy efficiency of destruction is shown."

Jan 1, 2014

By Denise Crocce Romano Espinosa, Andrea Moura Bemardes, Jorge Alberto Soares Tenorio, Daniella Cardoso Buzzi, Tatiana Scarazzato

"In copper plating processes, a fraction of raw materials are incorporated to the final products, while other portions are discarded as effluents. In this study, the application of electrodialysis (a membrane treatment process) was studied for treatment of wastewaters from cyanide-free strike baths, in order to reuse the components of this bath: copper and HEDP. The synthetic solutions studied consider 1 % of ion concentration of the bath used in this process, simulating the rinsing waters to be discarded. The electrodialysis allowed a percentage extraction up to 73% of copper ions and 72% of HEDP from the effluent. Complexes formation between the acid and copper indicates the possibility of recovery of components in the same compartment, obtaining a concentrated solution of these substances that can be reinserted in the process, for compensating drag-out losses. A diluted solution is also obtained, that can be reused as water in rinsing tanks.IntroductionIn metal finishing industries, contaminants in wastewater and the type of treatment required are determined according to the type of operation [l]. Generally, electroplating industries employ conventional wastewater treatments, e.g. oxidation of cyanide and chemical precipitation. This stage promotes reactions with soluble compounds to produce an insoluble precipitate, removed by physical separation. The sludge is dried by press-type filters [2].In this manufacturing sector, part of the raw materials are discarded as hazardous waste. The cost of discarded compounds and the treatment and disposal of waste may compromise profit margins. In addition, water consumption per unit of production stimulates the development of methods able to recover and reuse the largest possible amount of water [3].In some plating processes, cyanide-based substances are used as complexing agents and as raw materials in form of metal salts [4]. However, the toxicity associated with cyanide has been promoting research for the development of new raw materials in plating processes.A study conducted in Brazil [4] evaluated the modification of a commercial cyanide-free bath for processes of copper coating on Zamak. In the performed study, a new alkaline copper bath was formulated using l,hydroxyethane-1,1-diphosphonic acid (HEDP), an organic compound known for forming stable complexes with metal ions.As results of the study, the operational conditions and the formulation of a bath to obtain adherent, uniform and bright layers were established (Table I) [4]."

Jan 1, 2014

By Nikolaus Schneider

"Abstract: The combination of failure in joints of diaphragm walls and their exposure to water pressure may have far reaching effects ranging from water leakage to the risk of catastrophic loss of stability for the retaining wall and civil structures behind it. Investigations of imperfect joints in diaphragm walls have led to the development and testing of a quality tool to monitor the joint integrity of diaphragm walls during construction. By applying independent mechanical sensors (“joint inspector”) to the steel frame of hydraulic or mechanical grabs, it is now possible to record the surface conditions of exposed primary joints during the construction of secondary panels. This allows for the implementation of corrective action during the construction process should joint quality not indicate a watertight connection to the adjacent panel. The joint inspector, used for different types of stop ends, was tested on a full scale test field at several construction sites. The implementation of this new quality tool drives a new quality standard for deep excavations in inner city areas.General introduction to diaphragm wallsDiaphragm walls are reinforced concrete elements constructed using bentonite slurry to temporarily support an open trench in the ground. They are used in two main fields of application in civil construction, as foundation elements for vertical and horizontal loads (barrettes) and as retaining walls for excavation pits.Particularly for deep excavation pits in inner city areas, diaphragm walls are used as temporary or permanent walls of retaining walls. Alternative retaining wall systems would be secant pile walls, sheet piles or soldier piles, but these have disadvantages in structural strength when compared to diaphragm walls. If the vertical load of existing buildings next to the excavation pit has to be accommodated, the most practical solution can be found using diaphragm walls supported by prestressed anchors, steel struts or slabs."

Jan 1, 2014

By Cang Daqiang, Li Yu, Liu Xiaoming, Zong Yanbin

"Utilization of high-quality heat in melting slag is a great challenge for iron and steel industry. In the paper, a new method is put forward to concurrently utilize heat and slag by converting the melting slag directly into high valued materials, slag glass-ceramic. A glassceramic with a higher basicity of 0.7 than traditional basicity of 0.45 was prepared from steelmaking slag in order to utilize more hot melting slag. Effects of Alz03 on its crystallization processes were researched by XRF, DTA, XRD and SEM. Results show that Alz03 in glassceramic would have great effected on its property. When the Alz03 content ranges within 12%-15%, glass-ceramics with basicity of0.7 could reach the best performances. The change of dominant phase in glass ceramics from akermanite and wollastonite to akermanite and gehlenite would significantly degrade its mechanical property. An increase of Al2O3 content leads to a rise of the viscosity and crystallization activation energy of the glass, while results in increasing sintering temperature and crystallization temperature of glass, which contributed to its fully crystallization and densification process.IntroductionSteel slag is a by-product under a process of converting iron to steel at above 1600°C, and 0.1-0.15 ton molten steel slag would be discharged for producing per ton of steel in the process. The discharged steel slag at 1600°C has heat of 68 kgce/t. In 2012, China's steel output reached 716 million tons, and produces about 100 million tons of steel slag and 68,000 tee of heat in it [1,2]. But at present, utilization of both slag and its heat at 1600°C is a great challenge for iron and steel industry.Dry granulation of melting steel slag by air and then recovering the heat of the hot air are a traditional technology which have not yet been put into practice for very low heat conductivity of the slag and low efficient of heat exchange among the different processes [3,4]. Therefore, a new method for high efficient utilization of both steel slag and its high temperature sensible heat is put forward [5,6], which is on-line reducing and extracting iron from molten steel slag and then directly preparing glass-ceramic by use of the residual molten slag."

Jan 1, 2014

By T. Gong

Often plans to increase plant throughput provide an opportunity for optimising plant equipment and operating methods. This was the case in 2005 at TISCO Jianshan Iron Mine, when an increase in production was planned. The thickening circuit had presented a limitation to the plant throughput and operation with poor overflow clarity and underflow density. Following a course of test work by Outotec, a 53m diameter Supaflo® High Rate Thickener (HRT) was selected for the duty. From early stages of operation of the new thickener, the benefits have been dramatic, including: ? Improved tailings underflow density by 9% ? Improved Overflow clarity to less than 150ppm ? Considerably decreased the water and energy consumption as well as operation cost ? Stable and reliable operation This paper looks at this installation as a case study and compares the previous thickener installa-tion performance with the performance of the single 53m HRT.

Jan 1, 2014

By Amirhossein Molavi Tabrizi

In this paper we introduce a realistic model for mine openings that explicitly considers the effects of local irregular topography. Also, we consider the effect of entry orientation and rock anisotropy on the induced stress fields around mine openings under the given in-situ stress field. A triangular mesh formulation is derived for representing complicated irregular surface topography and underground openings. Each element contains three internal collocation nodes. Parts of the surface which are far from the mine openings are discretized by infinite elements. The rectangular infinite elements with three internal nodes are introduced specifically for this problem so they are compatible with the triangular elements. With the corresponding boundary element method (BEM) formulation, we then investigate the combined effect of the topography and entry orientation on the stress fields induced by openings in anisotropic rocks under in-situ stresses. A single rectangular opening in the anisotropic ground with topography and in-situ stresses is simulated using data from the Carroll Hollow mine in Ohio. The results of these simulations show that topography, rock anisotropy, orientation of the regional stress field and mine opening geometry all have appreciable effects on the stress fields around underground openings, yet these factors can all be accounted for in an efficient code with no need to discretize the model domain. Future applications using this new BEM formulation will provide useful guidance on selecting the optimal opening orientation in the mine in order to minimize undesirable stress concentrations around underground mine workings.

Jan 1, 2014

By Lev Filippov, Lorène Dessalas, Inna Filippova, Yves Foucquet

"Seafloor massive sulphide (SMS) deposits, similar in composition and genesis to terrestrial volcanogenic massive sulphide deposits, are generally found in volcanic seafloor environments along major rifts and mid-ocean ridges. Theyare associated to extensional tectonic settings such as nascent-arc, rifted-arc and back-arc environments. They may represent important source of base metals and be an alternative to on-land resources. Seafloor massive sulphide deposits have particular mineralogical compositions and textural features differentiating them from terrestrial one. When extracted from salty water and exposed to the ambient air, massive sulphide samples strongly oxidize and soon become covered by thin layers of iron, copper and zinc rich sulphates and oxides, as well as elemental sulphur. The textural properties vary according to the degree of maturity and the sample position within the hydrothermal deposit. The total porosity of that type of samples is also relatively high, especially for immature samples such as black smoker chimneys, which can reach 15% of total porosity. Because the secondary mineralization and porosity level are different, seafloor massive sulphides ores respond differently from terrestrial ore to processing methods. Froth flotation, commonly applied to separate all type of sulphides from the gangue, is one possible technique for processing seafloor ore. Sulphide recovery rate is, in most cases, excellent (>90%) however separation of the various mineral phases is difficult to obtain even when applying known methods used for terrestrial ore. Moreover, the flotation behaviour decreases drastically with the time of conservation at the surface, even when the samples were stored in a confined environment. High pH values, which is a good way to depress pyrite and therefore to favour the flotation of copper and zinc sulphides, do not have the same effect on seafloor ore. Consequently, careful flotation procedure must be elaborated to obtain efficient mineral separation technique for this specific marine ores."

Jan 1, 2014

By Y. Z. Ma

This paper presents a matrix formulation of factorial kriging, and its relationships with simple and ordinary kriging. Similar to other kriging methods, factorial kriging can be applied to both stationary and intrinsic stochastic processes, and is often used as a local operator. Therefore, the concepts of intrinsic random function and local stationarity are first briefly reviewed. Kriging is presented in a block matrix form in which the kriging solution is useful not only for understanding the relationships between simple and ordinary kriging methods, but also the relationships between interpolative kriging and factorial kriging. When used as a signal/noise-filtering method, factorial kriging is especially useful for multiscale modelling. Examples for general signal analysis and geophysical data signal filtering are given to illustrate the method..

Jan 1, 2014

By Christopher Tucker, Marcello Veiga

Social issues are increasingly recognized as significant inhibitors to mineral development projects. Increasingly social risk is being recognized as a key factor determining the success of a mineral investment. Groups opposed to a mine for social or political reasons often use environmental impacts, real or perceived, to prevent mine development. These risk factors depend largely on cultural perceptions of mining activities and must be understood as such in order to be appropriately managed. A first step to addressing social issues is inclusive, transparent and meaningful engagement of stakeholders. This process allows stakeholders to understand what the other parties value in order to collectively establish a common currency for development and the creation of mutual value. Expanding the scope of benefits and values a mine can bring is of increasing importance to mining companies who typically consult outside specialists remote from the mine site and late in the development timeline for this purpose. Training technical staff, engineers and geologists, who make initial and ongoing contact with local interests, in a holistic approach to mine development is crucial to successful and economic mineral development projects. Further extending this conversation to the general public, media governments and non-governmental organizations is a necessary step in developing a meaningful discourse on the benefit of mining activities.

Jan 1, 2014

By J. Vilcáez

The copper extraction yield from thermophilic bioleaching of chalcopyrite depends on temperature, pH, and the oxidation-reduction potential (ORP), as well as the activity of the microbe used. We studied copper extraction yields obtained from chalcopyrite with three thermophiles, Acidianus brierleyi, Sulfolobus metallicus, and Metallosphaera sedula, under various pH and temperature conditions and with different initial amounts of ferric iron. The results indicated that the capacity of each thermophile strain to leach iron as Fe3+ differed, which affected the influence of pH, temperature, ORP, and microbial activity level on the yield of copper. Microbial activity can cause ORP to be close to the critical value (450 mV) at which copper extraction at 65 °C can be higher than that at 80°C. An initial pH of 1.5 retards the precipitation of jarosite, allowing temperatures as high as 80°C to result in copper extraction yields close to 100%. However, if a thermophile with a poor capacity to form Fe3+ is employed, 100% copper extractions can also be obtained at pH 2.5, because ORP is low as result of low amounts of Fe3+ in solution. Optimum temperatures for the growth of thermophiles did not always mean high copper extraction yields. Conversely, high biomass concentrations depending on the capacity of the thermophile strain to leach iron as Fe3+, can result in excess Fe3+ in solution, leading to the precipitation of large amounts of Fe3+ as jarosite. The bioleaching capacity of A. brierleyi was reduced or suppressed when insufficient initial Fe3+ was pro-vided to trigger the leaching reaction, whereas S. metallicus and M. sedula were less sensitive to the initial availability of Fe3+. This result confirmed that a direct enzymatic attack on the mineral surface could initiate the leaching reaction, but later ORP governed the leaching rate of chalcopyrite.

Jan 1, 2014

By Thenepalli Thriveni, Seong-Young Nam, Nam-Il Um, Joobeom Seo

In the present work, we report a novel microstructure of synthesized scalenohedral PCC (precipitated calcium carbonate) without any additives by a simple and ecofriendly carbonation process carried out in a liquid-gas system on the crystal growth of the scalenohedral calcite phase. Especially, the process parameters of Ca(OH)2 concentration and CO2 flow rates were investigated to enhance the sensitivity of the process. The highest average length of the scalenohedral calcite was obtained at pH 6.0, temperature 450C, Ca(OH)2 concentration 0.2M, CO2 flow rate 80mL/min, and total volume 1L. The utilization of flue gas-derived CO2 from coal fired power plants could be a form of carbon capture and storage using carbonation reaction with scalenohedral PCC. Finally, the synthesized scalenohedral PCC was used as a filer for ONP recycling. We demonstrated all these experiemnts at semi pilot plant scale.

Jan 1, 2014