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By Vishal Shukla, Ashok Kumar, C. Raghu Kumar, D. P. Chakraborty

"Traditional iron ore beneficiation plants using washing, screening, and jigging processes require large volumes of process water. Generated slime during processing, its disposal and impact on water usage, is an important concern for any mining company. The challenge today, during extracting iron ore, is how to dispose of slime such that it is contained and stable, while maximizing water reuse and minimizing surface footprint. The slime disposal methods are sensitive to the environment. Two major technologies presently being practiced for disposing the slime across the world are pressure filtration and paste thickening. In this perspective an attempt has been made to do comparative study between paste thickening and pressure filtration for selection of suitable slime disposable technology for Noamundi processing plant, Tata Steel. From the studies, it is evident that by adopting pressure filtration technique it was possible to produce filtered slime, whereas filtration, rate reduces significantly with the presence of finer fraction. Further , the greatest advantage of paste thickening is volume reduction of slime. By considering the technology limitation and comparative lab test work result, it is opined that combination of filtration and paste thickening technology is favorable in terms of capital and operating cost and slime >45 µ should be filtered and < 45 µ slime should go for paste thickening. The study and the results are presented in details.INTRODUCTION The beneficiation processes always end up with an enriched portion of desired mineral - “Concentrate” and an enriched portion of undesired minerals - “Tailing”. The proportion and nature of tailings generated in every beneficiation process differ from ore to ore and reflects the characteristics of the feed processed. The traditional method of tailing disposal in many mineral processing industries has been to dispose them as thickener underflow at around 35% solids. Though, it had certain advantages of transportation with ease but contribute to a greater volume occupied in the tailing dam. This sustained practice and failure to utilize the space available in the tailing dam judiciously endangered the mining industry. The tailing management has become the toughest task to the mining industry and most of the mines are running out of space for disposing the fresh tailings as many of these are at the verge of getting filled."

Jan 1, 2018

By Yang Zhao, Tao Xiu-xiang, Chen Song-jiang

"China is rich in low-rank coals that account for 45.68% of existing coal reserves in China. The clean and efficient utilization of low rank coals is of great significance for ensuring the effective energy supply and promoting economic development and environmental protection. In order to solve the difficult problem in flotation of low rank coal, it has become the focus of research in the related field that oily bubbles instead of air bubbles are taken as a carrier in flotation to improve the attachment efficiency and recovery of low rank coal. In this paper, low rank coal slime collected from Shendong mining area was used as the experimental material, and it focused on the characteristics of oily-bubble flotation process of low rank coal. Additionally, difference in conventional flotation and oily-bubble flotation was discussed. The induction time between air bubbles, oily-bubbles and fine low rank coal particles was measured. The results indicated that the induction time between oily-bubbles and coal particles was obviously lower than that of air bubbles. By comparing the foam height of air and oily bubbles, it was found that the amount of oily bubbles is less than air bubbles, causing relative low flotation rate of oily-bubble flotation at initial stage. Besides, the maximum foam height and half-life of air bubbles and oily-bubbles were measured respectively. The results showed that the stability of oily-bubbles was higher than that of air bubbles, which is benefit for the enrichment of concentrates. The clean coal water recovery of oily-bubble flotation is lower than that of air bubble flotation, which indicated oily-bubble flotation is lower in water entrainment. INTRODUCTION China is the largest energy consumer in the world, accounting for 23% of global energy consumption in 2016 and 27% of global energy consumption growth. Whereas coal is taken as the major primary energy source and its share of China’s primary energy consumption is 62% in 2016, in which the low rank coals, such as lignite, long-flame coal, weakly caking coal, and non-caking coal, accounted for about 50% of total coal production capacity (China’s energy market in 2016, BP). Moreover, the exploitation and utilization of low rank coals and other coals that are difficult to float have been an important strategy for China’s sustainable development of the coal industry (Liu et al., 2014). However, the combustion of low-quality coals leads to a serious environmental pollution. In addition, the deterioration in geological conditions of coal resources, and the increasing improvement in the mechanization for mining significantly caused the increased amount of fine coal."

Jan 1, 2018

A new short combined flow sheet including high intensity magnetic separation and flotation for a rare earth ore in Maoniuping deposit, China has been investigated. Massive conclusive results demonstrate, that it is critical to separate the ore by high intensity magnetic separation prior to flotation for tons of slimes and nonmagnetic gangue existing. The vital technological parameters affecting flotation have been studied in detail. Modified hydroxamic acid is an efficient collector for bastnasite flotation because of its high selectivity. Flotation results also indicate high temperature that play an unfavourable role on the recovery as well as the grade of bastnasite concentrate, when the rare earth ore is floated with modified hydroxamic acid and sodium silicate depressant. Bastnasite concentrates, averaging over 65 percent REO at an overall recovery of 82-84% is achieved by the new beneficiation technology. Keywords: bastnasite, REO, magnetic separation, flotation, chelating collector, desliming

Sep 1, 2012

By M. M. Yahyaei

The Sarcheshmeh new concentration plant uses a 32 ft×16 ft constant speed (10.5 RPM) SAG mill with two 5500 hp motors which could rotate in two directions. The mill liners are chrome-molybdenum steel casting type with a Brinnell hardness between 325 and 375 with the lifter face angle of 14° and lifter height of 152 mm. The shell liner consists of 120 (two 60 rows) pieces with a High-High configuration in a rail design. A specially designed liner wear profile measuring device enabled fast and accurate measurements inside the mill during the mill shut-down periods. The measurements indicated that the liner wear profile along the liner length is non-uniform and the highest wear occurs between 1.25m and 2.75m of the mill length. The average weight of liners at the time of removal was 47% of the original weight indicating a significant metal loss. The modification of liner shape was undertaken with the aim of having a uniform profile at the liner removal time. The proposed liner unlike the pervious type did not have a uniform shape with a lifter height of 187mm at the section where the wear rate was high. It was believed that this new profile could arrive at a uniform profile at the liner change out time. A study was also directed to the possible change of charge motion due to the liner profile modification. The dynamic behaviour of charge was investigated through the analysis of forces acting on a single ball using mill characteristics such as mill diameter, rotational speed, lifter height and release angle. The simulation of charge motion with this method and Milltraj TM software indicated that the impact position of charge will change only one degree due to the maximum increase of 35 mm in the lifter height. This assured that the installation of the modified liner would not have any adverse effect on the mill because of ball impacting the mill shell. It was predicated that the amount of scrap metal will reduce to 30% from the current value of 47% beside 1500 h increase in the liner life time.

Jan 1, 2014

By F. Q. Cheng

As the important potash, the product yield of KCl in winter is low and the resources waste is serious according to the deficiency of collectors, which can be used in this condition currently. This paper studied on the change of contact angle, turbidity, and flotation recovery of KCl particles when different chain lengths, ratios of amines were used as collectors in KCl flotation process to get a new mixed collector. The contact angle values of KCl crystal in its brine solution added different amine collectors were first measured by captive bubble method. The turbidity of brine solutions were then measured by the laboratory turbidimeter at room temperature when different amine collectors were contained. In the end micro-flotation experiment using mixed amine with fixed ratios and ODA as collectors respectively at 5 °C, 23 °C were performed. The results show when the ratio of the mixed amine is DDA- 20%, ODA-60%, C20-20%, the contact angle at KCl surface is the maximum and the hydrophobic state is best. Meanwhile the result of turbidity measurement indicates that the dispersion of mixed amine colloids is better than the ODA collector due to the addition of DDA, which plays the role of frother. The flotation results also prove that the mixed amine is not only fit for the KCl flotation at room temperature but also fit for its flotation at low temperature. This study provides strong technical support to extend the production time of potash business in Chaerhan areas in China.

Sep 1, 2012

By John A. Herbst

The Mineral Processing Industry needs accurate Production Simulators for the design of future plants and expansions. To achieve this, these simulators should not only provide an accurate portrayal of the dynamics of individual pieces of equipment they should include the impact of discrete stochastic events such as scheduled and unscheduled maintenance so the relationships between availability, equipment sizes, and plant capacity are understood. To provide such a tool accurate dynamic Population Balance Models need to be combined with solid discrete event modeling. The current paper provides a description of how these two disparate modeling techniques were combined and the associated benefits from this combination. Keywords: dynamic plant simulation, population balance models, discrete event models, prefeasibility and feasibility studies, plant design and expansion

Sep 1, 2012

By Ana C. C. Pacheco, Maurício L. Torem

"The aim of this work was the study of the effect of the type (Fe3+, Al3+ and Fe3+ and Al3+ mixture) and of the coprecipitant concentration on As5+ removal by ACF. Removal of As5+ using Sodium Dodecylsulfate (SDS) as a collector was studied by Adsorbing Colloid Flotation (ACF) at laboratory scale. The morphology of the precipitate retained in the foam was analyzed by Scanning Electron Microscopy (SEM/EDS).By comparing the coprecipitant type and concentration studies it could be concluded that As5+ removal in the presence of Fe3+ (160 mg.L-1) alone, or a Fe3+ (80 mg.L-1) and Al3+ (40 mg.L-1) mixture, is equivalently effective (99,9%) and greater than in the presence of Al3+ (80 mg.L-1) alone (97,7%).Through SEM/EDS analyses, it was possible to observe that both morphology and composition of the precipitate produced in the solution and retained in the foam depend on the physico-chemical conditions of the system, that is, on the species present in the solution."

Jan 1, 2003

By Zehong Wang

Selecting sodium polyacrylate (PAAS) as grinding aid, the effect of grinding aid on the grinding efficiency of bauxite taken from Shanxi province was studied and its mechanisms were analyzed by measuring the variation of adsorption characteristic, pulp viscosity, surface electric potential of the bauxite and the surface appearance of particles. The results showed that, compared with no grinding aids added the content of -0.074mm in the ground product was increased by 5.45 percentage points under the optimal grinding conditions adding PAAS as grinding aid when the amount of PAAS was 0.7%wt of bauxite. Because the physical adsorption and chemical adsorption were occurred on the bauxite surface, which could reduce the pulp viscosity, change the surface electric potential of the bauxite, enhance the surface appearance of particles and lower the surface hardness of the bauxite, the grinding efficiency of bauxite was increased by PAAS. Keywords: bauxite, grinding aids, grinding efficiency, mechanism

Sep 1, 2012

By Mike Hollitt

The first decade of the 21st century was one of fundamentally changed dynamics for the minerals industry. Following intense globalization commencing in the late 20th century production is now concentrated into large businesses that can compete across geography in diverse commodities. Asian industrialization and urbanization is now the main driver of growth in demand for energy and materials. Demand for the output of these industries has risen sharply, reversing decade long trends to reduced real commodity prices. Supply responded with expansions of existing mining and processing operations, and large investment in new resource development. Development of new, lower grade or more remote resources was stimulated. Resource development by global entities in frontier environments reinforced the importance of effective forms of social contract, and of stronger environmental performance. The worst economic shock in decades provoked no significant pause despite large impacts on corporate ownership. State owned enterprises commenced unprecedented foreign direct investment in minerals and energy resources. A thrust towards resource nationalism re-emerged as governments sought to ensure that the export of state owned resources contributes more strongly to government revenue, reducing the burden of trade in scarce resources on other trade-exposed sectors. The unprecedented combination of forces at work has made future predictions difficult, with day-by-day volatility in anticipated corporate fortunes, and investment plans. The challenge for process innovation (and for exploration) has been to keep up, maintaining a lid on costs as lower grade and more challenging ore bodies are brought on quickly in a context of competition for land use, community expectations and continued care for natural and living environments. While new projects have provided the necessary platforms for implementation of innovative approaches, there is evidence that a gap may have emerged between the pace of growth and the pace of innovation. The history of a century of process innovation in the context of growth of output, declining resource grades and commodity prices is presented. The necessary conditions for accelerated process innovation are considered, and future needs and approaches are discussed. Keywords: process innovation, resource development

Sep 1, 2012

By H. M. Yang

Structural alteration of pyrophyllite during mechanical activation in a planetary mill was investigated by X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) techniques. Mechanochemical effect markedly promotes the decrease in reflection intensities with increasing the grinding time. Prolonged grinding causes the pyrophyllite to become the amorphous structure. It can be indicated that pyrophyllite is very susceptible to alteration by grinding. Crystal size (d006) of pyrophyllite appears to be a limit after 2h grinding. IR spectroscopy analysis shows a little alteration in the bands of pyrophyllite after mechanical activation. The results indicate that the ordered structure of pyrophyllite is destroyed and lattice deformation occurs. Porous silica was then successfully prepared via leaching the mechanically activated pyrophyllite. Pyrophyllite was first ground for 6 h. Ground samples were subsequently leached with 4 M hy-drochloric acid at 80 °C for 2 h to produce porous silica with specific surface area of 188.1 m2/g, total pore volume of 0.18 mL/g and average pore size of 3.9 nm from N2 adsorption analysis. Otherwise, the porous silica obtained from direct leaching of the original pyrophyllite only has a specific surface area of 4.3 m adsorption analysis. 2/g and total pore volume of 0.03 mL/g. It is inferred that grinding is favorable for the formation of microstructure pores. It offers a simple and convenient route for the preparation of porous materials from natural minerals.

Jan 1, 2014

By Bhargav Dhavala, Sristy Raj, Ashok Kumar, Suman Krishna Sit, Adity Ganguly, D. P. Chakraborty

"Tatasteel’s West Bokaro washery#3 is designed to deslime raw coal at 0.5mm; the oversize (+0.5mm) is beneficiated in dense media cyclones (DMC) while the undersize (-0.5mm) is beneficiated in froth flotation (FF) cells. Nearly, 80% of the raw coal feed reports to the DMC circuit consisting of four parallel streams. Presently, the performance of DMCs at washery#3 is interpreted by: (a) comparing the actual plant yield w.r.t the lab predicted yield and (b) misplacement of clean coal to middllings.However, the comparison between actual & lab predicted yield is fallacious given the fact that the lab predicts yield of the borehole sample while the feed received at the plant has different characteristics altogether due to the dilution during mining. To mitigate the said limitations, a quick diagnosis tool using the past data has been developed that will give a prediction of performance of different coal seams in the DMCs, inputs being feed ash to DMCs and stream wise feed specific gravity (coal & magnetite combined).The tool also will help in identifying the root cause on real time basis thereby helping the operator to take necessary corrective actions. The operator can intimate the mining personnel in cases of shale reporting to the feed as a result of dilution during mining. In events of higher standard deviations between the parallel streams w.r.t feed specific gravity, the operator can adjust the parameters accordingly to minimize the yield loss. INTRODUCTION West Bokaro came into existence in 1948, as an independent coal company, managed by M/S Anderson Wright. Tata Steel acquired the Company in 1956 to meet its requirement of metallurgical grade coal for Iron making. Subsequently, in 1976, it was made a division of Tata Steel. In 1974, when coal mines were nationalized, West Bokaro was exempted as it produced coal only for captive consumption of the Steel Works. The first washery of India was set up in West Bokaro. The business objective of the West Bokaro division is to produce clean coal at optimum cost for captive use in the steel plant of Tata Steel at Jamshedpur. The strategy is to reduce ash with minimum loss of yield so that quality of coal improves and yet the cost is beneficial vis-a vis imported coal. The primary product is the metallurgical grade coal for coke ovens, which converts coal into coke for use in the Blast Furnaces."

Jan 1, 2018

By G. Aguilera

The mineral suspensions do not present a newtonian behavior as their continuous phase; they can be pseudoplastic, dilatant, or both. The viscosity becomes as the most important rheological variable because the different industrial processes involve a wide variety of rheological scenes, with a specific rheological behavior for each one. Some authors have tried to model the viscosity of suspensions considering the volumetric fraction of solids and others have also kept in mind the size of the particles (Einstein, 1906; Batchelor, 1977; Jinescu, 1974; Krieger and Dougherty, 1959; Tangsathitkulchai and Austin, 1988). Others consider the shear rate (Cross, 1965; Hershel-Bulckley, 1926; Bingham, 1916, etc). However, none of the models is able to simulate the viscosity involving the physical, chemical and mechanic factors at the same time for crowded suspensions. A new model based on Neural Networks is presented, taking into account all the variables of ceramic clay suspensions and chemical additives. Keywords: viscosity, clay minerals, neural networks, simulation, mathematical function

Sep 1, 2012

By M. Marinov

The Bulgarian deposits of quartz-kaolin raw materials are localized in the NE Bulgaria. For many years, the quartz-kaolin sand separation has been performing by water washing technology. After wet separation the raw material yields two products ? washed kaolin (different grades) and quartz sand (different grades). Research and development program has started to improve the quartz-kaolin sand separation. The program has undertaken an increasing of processing capacity, to decrease the losses in the tailings and to provide production of new quartz sand grades. The kaolin-silica raw materials from Vetovo open mine and the technological tailings from Vetovo processing plant were characterized. It was established that there are a lot of losses of quartz in final tailings. New approach on kaolin-silica raw material separation was tested in laboratory scale. The test work was performed on Derrick Stacksizer screening machines. The results of laboratory experiment show that there are possibilities to increase the quartz sand recovery and to start the production new grade sand. The full-scale pilot test was performed including the following units: two Derrick Stacksizer screening machines equipped with 0.430 mm and 0.150 mm opening Derrick Urethane Panel, respectively; Flat bottom DN 500 Hydrocyclone and DN 100 Hydrocyclon. The pilot test data clearly demonstrate that the Derrick Stacksizer screening machines are suitable for Bulgarian silica-kaolin raw material. Based on the test data a new quartz-kaolin separation technology was developed. The new technology was introduced in Vetovo processing plant increasing processing capacity and decreasing the losses of quartz in final tailings. Additionally the production of silica sand grade PK 0.16 is increased and starts the production a new grade PK 0.10.

Sep 1, 2012

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 J. Zou

With the increasing applications of the Chinese metal magnetic liners, the requirement for their technical specifications has become stricter and stricter. It is necessary to deeply analyse the metal magnetic liners in order to improve their reliability and economics. The key issue of metal magnetic liners is magnetic forces: their attractions to mill shell and protection layer. Mathematical models were developed using finite-element analysis software and systematic simulation analyses of the two most critical indexes of magnetic liners were performed to find out the most important parameters and their effect on the liner?s characteristics. The relationships between magnetic forces and installation gaps, thickness of permanent magnets and thickness of protection layer may be used to guide the design of metal magnetic liners for ball mills in order to achieve good economic indexes.

Jan 1, 2014

By I. Dymov

"The extractive metallurgy of precious metal ores involves gravity concentration, flotation and cyanide leaching. Pre-oxidation, such as roasting, autoclaving, bacterial oxidation and other techniques, is required for processing refractory ores. Selection of the process is mainly driven by the grade, reserve and mineralogy of the target elements. The concentrations of precious metals in the crust are extremely low and highly variable, resulting in ore variability in many gold, silver and PGE deposits. More importantly, precious metals in an ore may occur in two or three forms (i.e. microscopic, submicroscopic and surface-bound), making ore processing of precious metals extremely challenging. The objective of geometallurgy and process mineralogy is to reduce and minimize the technical risk in project evaluation, process selection, mine planning and production forecasting through geometallurgical modelling, representative sampling and subsequent systematic mineralogical characterization and metallurgical testwork. Geometallurgy is a technique to document variability within an orebody and quantify and evaluate the impact of many factors including geology and mineralogy on grinding, flotation, leaching and metal recovery processes, while mineralogy is one of the major predictive and trouble-shooting tools for many new mineral projects and operating mines. This paper presents an overview of fundamentals, methodologies and techniques applied in geometallurgy and process mineralogy and highlights the importance of both disciplines in process selection and plant optimization with applicable case studies. INTRODUCTION Precious metals, including gold, silver and platinum group elements (PGE) occur in various geological settings and ore types. The concentrations of these metals in the crust are extremely low and highly variable, resulting in ore variability in many gold, silver and PGE deposits. More importantly, precious metals in an ore may occur in two or three forms (i.e. microscopic, submicroscopic and surface-bound), making ore processing of precious metals extremely challenging. Process selection is most important in any precious metals project and is mainly driven by the grade, reserve and mineralogy of the target elements. Free-milling ores, such as Kupol in Russia, Hemlo in Canada, Grasburg in Indonesia, UG-2 in South Africa, Lac des Iles in Canada, and Noril’sk in Russia, can be processed using flotation or cyanidation with or without gravity. B2Gold Corp, a Canadian gold company, just started a number of new and under construction free-milling gold operations such as Fekola mill in Mali, Mastbati mine in Philippins and Otjikoto mine in Nambia. However, refractory ores (particularly gold ores), such as the Carlin and Goldstrike mines in the USA, Giant in Canada, Pueblo Viejo in Dominican Republic, Porgera and Lihire in PNG, Kittilla in Finland, Fairview in South Africa and Shuiyindong in China, must be processed using pre-oxidation prior to cyanide leaching. In some mildly refractory gold ores, such as Kumtor mine in Kyrgyzstan and KCGM in Australia, ultrafine grinding is required to liberate fine-grained gold particles. For some gold ores containing both free-milling and refractory components (such as Cripple Creek mine in Colorado, USA), two or more recovery processes may be required. The variability of grade, metal deportment, ore hardness and other parameters is one of the risks that encountered in development and operation of many precious metals projects. To minimize and reduce the technical risk caused by ore variability, geometallurgy and process mineralogy have been used by mining companies in the last two decades to measure and quantify the spatial variability of the deposits that are being developed. This paper presents an overview of fundamentals, methodologies and techniques applied in geometallurgy and process mineralogy, it highlights the importance of both disciplines in process selection and plant optimizat"

Jan 1, 2018

By Wenqing Qin, Yunfan Wang, Ximei Luo, Fen Jiao

In order to investigate the effect of nanobubbles on adsorption of surfactant on mineral surface, the nanobubbles on the surface of calcite with -37µm fraction in the sodium oleate system were controlled by pressurization and decompression to mixing vessel. Subsequently, the adsorption amount of sodium oleate on the surface of calcite were detected by ultraviolet spectrum at different stirring times and different pressures. At the same time, the nanobubbles on the calcite surface were imaged with atomic force microscopy (AFM). In addition, a homemade vacuum Hallimond tube device was used for the flotation of single mineral, and the grade and recovery of minerals in concentrate was used to determine the influence of the nanobubbles on flotation. The experimental results showed that a large number of nanobubbles were found on the calcite surface by AFM under the dissolved oxygen difference (DOD) condition of -4 mg/L. And a large difference in adsorption capacity of sodium oleate on the surface of calcite was observed under different air pressure conditions. It indicated that the ambient pressure had a certain effect on the adsorption of sodium oleate on the calcite surface, and this effect did not depend on the constant low pressure or constant normal pressure, but depended on the changing process of pressure. The single mineral flotation experiment results indicated the recovery of calcite under decompression condition (formation condition of nanobubbles) was 1.5-2 times that under constant normal pressure, and the flotation time is much shorter. Moreover, the recovery under constant normal pressure was greatly influenced by flotation time. In this paper, only one aspect of the effect of nanobubbles on mineral flotation was preliminarily explored. It was confirmed that after vacuum-pumping, the adsorption of sodium oleate on calcite surface could be increased, the flotation time also was greatly reduced and the recovery of calcite was increased.

Jan 1, 2018

By J. Seo, W. Kim, I. Bae

"Microcrystalline silica impurities such as quartz and opal-CT commonly associated in bentonite should be controlled and removed as far as possible when bentonite is used as biocompatible raw material because they show sufficient evidence of carcinogenicity. Since opal-CT contained in bentonite in trace amounts cannot be well separated by conventional sedimentation method, in this work, the ultrasound-assisted removal of the impurity was attempted. Irradiating ultrasound into bentonite-water suspension promoted the production of fine montmorillonite particles in the suspension and the production markedly increased when montmorillonite was activated by Na2CO3. Subsequent centrifugation of the suspension made it possible to recover pure montmorillonite particles as an overflow product. Only 16.2 mass % of total solids was recovered as an overflow from the non-activated suspension, whereas 63.5 mass % was recovered from the activated suspension at centrifuging speed of 10000 rpm. Increasing sonicating time enhanced the yield of overflow, however, excessive sonication up to 10 min hindered the purification of montmorillonite. It was observed that the peak reflection of (101) plane of opal-CT in overflow increased as sonicating time increased during prolonged sonication. INTRODUCTION Bentonite consisting predominantly of mineral montmorillonite is clay-rich soft rock generated frequently from the alteration of volcanic ash. Depending on the nature of its genesis, bentonite contains a variety of accessory minerals, which may include mainly quartz, feldspar, opal cristobalite/tridymite (opal-CT), calcite, illite and mica. The presence of these accessory minerals can impact the industrial value of the deposit, reducing its commercial value depending on its applications. Therefore, bentonite is often purified by removing these impurity minerals for special applications where specific properties and characteristics are required (Murray, 1999). Among the special applications, bentonite is often used in the cosmetic and pharmaceutical industry as both excipient and active ingredient in the forms of liquid (suspensions, emulsions), semi-solid (creams, ointments) and solid (powder, capsules and tablets). The basic requirements for bentonite to be used as raw material are pure, microbiological and mineralogical inertness. Physical properties such as swelling volume and gel formation are also important. Particularly, microcrystalline silica polymorphs such as quartz, cristobalite and opal-CT should be controlled and removed as far as possible because they show sufficient evidence of carcinogenicity in humans."

Jan 1, 2018

By J. Y. Xu

A mutant of Phanerochaete chrysosporium, which is capable of degrading lignin, was bred by ul-traviolet ray irradiation and this mutant strain shows high capability of degrading of lignite. The degradation ratio of original Yima lignite and nitric acid treated Yima lignite by this mutant are 37.6% and 51.62%respectively, whereas those by the original strain are 31.84% and 32.55% respectively. XRD and FTIR analyses of the lignite converted product show that its polymerization degree and average molecular weight are both greatly reduced. The content of the functional groups is also been altered.

Jan 1, 2014

By A. Shibayama

Soil contamination by organic compounds is one of the most concerned issues on polluted soil. It is well known that there are limited methods to remediate the contaminated soil on site. Especially, the in-situ method for contaminated soil is too difficult to de-contaminate the organic pollutant. In this study, the fundamental ability of soil remediation, which aimed to decrease oil concentration in, in-situ process, have been researched by using a high pressure gas generated from ?crush composition? on artificially oil contaminated soil. The n-hexadecane (n-C16H34) and other organic compounds were selected as soil oil contaminators, gravimetric analysis by soxhlet extraction and GC-MS were used as qualitative and quantitative analysing methods. For the experimental examination, the influences on the difference in the concentration of n-hexadecane (and other organics), the tamping amount, position and repetition of crush composition in soil, and scale (size) of experimental model were investigated. The n-hexadecane concentration reduced by the explosive effect of crush composition showed a reasonable decrease of about 30 wt%~60 wt% compared to the initial n-hexadecane. The removed amount of n-hexadecane and distance from explosion point of the crush composition was related in scale and model of contaminated soil.

Jan 1, 2014