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By Naoki Hiroyoshi, Hajime Miki, Tsuyoshi Hirajima, Masami Tsunekawa

Acidic solutions for chalcopyrite leaching contain cupric, ferrous and ferric ions, and the oxidizing power of the solutions is indicated by a redox potential, determined by the concentration ratio of ferric to ferrous ions. This paper reviews our previous studies on the redox potential dependence of chalcopyrite leaching in sulfuric acid solutions. Leaching and anodic-polarization experiments showed that coexistence of cupric and ferrous ions activate anodic dissolution of chalcopyrite, causing faster copper extraction at the potentials below a certain value (critical potential). The analysis of the AC impedance spectra for chalcopyrite electrode indicated that a high-resistance passive layer grows on the chalcopyrite surface without cupric and/or ferrous ions, and that coexistence of these ions causes a formation of another product layer and inhibits the passive layer growth at low potentials. These results are explained by a reaction model assuming the formation of intermediate Cu2S due to chalcopyrite reduction and the subsequent oxidation of the Cu2S. The critical potential corresponds to the redox potential of the Cu2S formation and the predicted values matched with the experimental results. Catalytic effect of silver ions on chalcopyrite leaching was also discussed based on experimental results and the above model.

Jan 1, 2003

By Kamalendu Bhunia

With the progressive depletion of known resources of good quality coal and minerals as well as the increasing demand of these minerals by different user industries, the emphasis has been shifted all over the world from selective mining to bulk mining followed by up- gradation to obtain the required quality of concentrate. The column flotation cell is one of the alternatives to reduce the gangue content of fines because of its inherent characteristics viz. easier to operate, low space required, no moving parts etc. A laboratory flotation column is used to conduct experiment. Present work has been undertaken to observe the effect of process variables (gas flow rate, feed/slurry flow rate, and frother concentration) on gas dispersion parameters (gas holdup, bubble surface area flux) in collection zone and to explore the effect of feed (slurry) inlet orientations and gas flow rate on column?s metallurgical performance. The effects of solid particle concentration, size and type (hydrophobic and hydrophilic) of solid on gas dispersion parameters have also been investigated. Test work has been performed in a continuously operating Perspex column (10 cm in diameter and 168 cm in height) using coal, sphalerite and dolomite as solid. Gas hold-up has been measured by phase separation method and mean bubble sizes are estimated from a drift flux analysis. The influence of operating parameters on bubble surface area flux has been discussed. It is observed that gas holdup in collection zone is affected by air as well as feed flow rates and also solid?s type. It is also found that addition of solid decreases the gas holdup and rate of decrease in gas holdup increases when solid concentration increases and particle size increases. Increase in gas flow rate increases recovery in collection zone due to increase in number of bubbles per unit volume of the column. From the experimental results it is evident that cross-current orientation of feed inlet shows slightly better metallurgical performance compared to other orientations. Keywords: column flotation, gas holdup, drifts flux, bubble size, bubble surface area flux, hydrophobicity, and recovery

Sep 1, 2012

By Venugopal Tammishetti

One of the important technological challenges facing the iron ore industry in India is to find commercially viable technologies to process alumina rich iron ore fines and slimes. The key to solving this problem lies in developing selective reagents for the separation of iron oxide minerals from associated gangue minerals like quartz, gibbsite, kaolinite and montmorillonite. We present in this paper our successful results on the dispersion-flocculation of three different natural iron ore slime samples from mines in India using the reagent combination of PVP dispersant and corn starch flocculent. All the three samples contained hematite, goethite, kaolinite and gibbsite minerals as confirmed by X-Ray Diffraction (XRD) analysis. The effect of various process parameters such as pH, dosage of reagents, settling time and pulp density was studied. We were able to produce a concentrate assaying 66.2% Fe and <2% Al with a yield of 67.4% by weight (with a recovery of 77% of iron values) using PVP (1 ppm dosage) and corn starch (20 ppm) for one of the slime sample (Sample I) assaying 58.2% iron (Fe) and 3.8% aluminium (Al). The XRD analysis of settled and dispersed fractions revealed that alumina-containing minerals like clay and gibbsite mostly remain in the dispersed phase while iron-bearing minerals tend to concentrate in the flocculated fraction. Keywords: iron ore, slime, flocculation, dispersion, beneficiation, starch, polyvinylpyrrolidone

Sep 1, 2012

By Priyanka Dhar, Kurt Aasly, Hanumantha Rao Kota, Hassan Bouzahzah, Maria Thornhill

The interest in investigating the processing characteristics of mineral deposits in Norway has seen an upsurge in the last decade. One of the major areas of interest is a huge copper deposit, operated by NUSSIR ASA located in the Repparfjord Tectonic Window in the caledonides of west Finnmark. This study reports analysis of ore from the deposit for development and modifications in the flotation flowsheet for the NUSSIR ASA copper ore. The mineralogical characterization for the ore sample was achived by optical microscopy and Zeiss automated mineralogy while grinding characteristics were tested using Bond Index tests. The results confirmed the presence of Cu minerals in the form of chalcocite, chalcopyrite and bornite in the samples, which are mainly liberated in the – 105 µm size range. The majority of non-liberated copper sulphides associated with silica and the carbonates varies from 3 to 28 percent in the –250 µm samples . It is also observed that the copper minerals are uniformly distributed in all size ranges. Selective flotation of NUSSIR copper ore was performed in different size fractions with a motive to identify the correct liberation size and thus to obtain a copper concentrate meeting the quality requirements. The flotation experiments are essentially performed in two stages: the rougher and the cleaner stage. Mass balance calculations were performed showing that approximately 88 percent of copper can be obtained at the end of the process. Ultimately, overall circuit copper recoveries ranged between 83.5 to 88.1 % with a concentrate grade of 35 to 48 % Cu.

Jan 1, 2018

By T. N. Alexandrova

Results of mineralogical-technological research of carbonaceous rocks of Kimkansky precious metal occurrence are presented, on their basis new typemorphic natural and technological microelement associations were revealed using mathematical statistics methods. Keywords: carbonaceous rocks, processing, microelements, flotation, statistical criteria

Sep 1, 2012

By Robert Snow, Shibo Zheng, Wenyi Song, Xiaoqing Ma, Patrick Zhang

Numerous phosphate mineral depressants have been reported in the literature for use during anionic flotation of dolomite from carbonate fluorapatite in slightly acid circuits. In one part of this research, laboratory flotation experiments were conducted to compare the effectiveness of phosphate depressants to process ground, deslimed high-MgO Florida phosphate pebbles. Ten potential phosphate depressants were evaluated during laboratory anionic flotation of dolomite from phosphate in a slightly acid circuit using a sulfonated oleic acid soap plus oil as the dolomite collector. Eight of the depressants have been used by various investigators with foreign and domestic carbonate-phosphate ores. Four of the depressants were found to be reasonably effective during the current flotation study, namely: sodium tripolyphosphate (STPP), sodium hexametaphosphate (SHMP), tetrasodium pyrophosphate (TSPP) and diphosphonic acid (DPA). Without depressants, the sulfonate collector required to produce cell underflow phosphate products containing <0.80% MgO and MgO/ P2O5 ratio <.033 was 1.13 kg/ton of flotation feed at a flotation pH range = 5.5-6.0. Using this collector level with 0.91 - 1.36 kg/ton of feed of STPP, SHMP or TSPP yielded phosphate products analyzing 0.73-0.92% MgO and MgO/ P2O5 ratios = .027-.034 at 90.0-96.8% P2O5 recovery. Similar grade phosphate products were obtained using DPA as the phosphate depressant at 84.1-87.5% P2O5 recovery. When no depressant was used, a similar grade phosphate product was obtained at only 65.9% P2O5 recovery. Another part of the research aimed at reducing MgO content in the final concentrate from Florida phosphate plants by conducting dolomite flotation on the final concentrate. Numerous phosphate depressants were tested for this purpose, including acidic, neutral and alkaline reagents. The most effective phosphate depressant was found to be phosphoric acid, giving both high grade and recovery.

Jan 1, 2014

By G. Semenchenko

Heterotrophic microorganisms Pseudomonas aureofaciens, microscopic fungi Fusarium sp. and their combinations with some chemical substances were used for gold leaching from refractory ore and flotation concentrateof Akbakaj deposit. All biological additives raised the speed of noble metals dissolution. The best results of gold extraction from ore were in the presence of bacteria or their associations with other solvents and from flotation concentrate in the presence of fungus - 30 % of additional amount of gold. The maximum extraction of gold speed value was during the first 8 hours of process. The electronic-microscopic researches of the ore samples showed almost complete decay of pyrite and arsenopyrite under bacteria influence whereas at chemical leaching most of these minerals stayed uncrushed. The presence of microscopic fungi in flotation concentrate during leaching provided full distraction of pyrite, but some crystals of antimony and arsenopyrite were undestroyed. During cyanide leaching of flotation concentrate there were accumulation of antimony and incomplete pyrite decomposition. Keywords: gold bioleaching, bacteria, fungi, complex solution

Sep 1, 2012

By Y. S. Sun, P. Gao

"In this investigation, a pilot-scale suspension magnetization roasting reactor was introduced and used to enhance magnetic properties of an iron ore. Consequently, the effects of roasting temperature, reducing gas CO flow rate and fluidizing gas N2 flow rate on the magnetization roasting performance were investigated. The results indicate that the hematite and siderite are almost completely converted into magnetite by a gas mixture of 3.5 Nm3/h CO and 2 Nm3/h N2 at roasting temperature of 520 °C. Under the optimized conditions, the magnetic iron concentrate with an iron grade of 60.18% and iron recovery of 90.17% was achieved. The XRD and Fe mineral phase analyses revealed that most of the hematite and siderite were converted to magnetite, and the magnetic properties were greatly enhanced. INTRODUCTION The steel and iron industry in China has rapidly developed in recent years requiring a large quantity of iron ores. Low-grade and complex iron ores are currently the overwhelmingly dominant mineral resource for iron in China. Therefore, China depends on imported iron ore resources heavily, resulting in an increase in the production costs of iron-making and steel-making[1-3]. Using domestic resources to produce a steady supply of high-quality iron ores is an important step toward the sustainable development of the steel and iron industry[4-5]. The iron ore from Jiuquan iron and steel company is abundant and recognized as typically complex iron ore resources in China. Magnetization roasting followed by low-intensity magnetic separation has been proven as the most feasible methods to upgrade refractory iron ore[6-10]. In present research, an innovative roasting technology, namely suspension magnetization roasting, was developed and applied to recover iron from a typical refractory iron ore. Suspension magnetization roasting technique and equipment developed by Prof. Yuexin Han’s Group at Northeastern University (NEU) is an effective way for the utilization of refractory iron ore. The advent of suspension magnetization roasting will, in China and even globally, produce a significant technological revolution in the field of iron ore beneficiation. Based on the previous works, this paper mainly described experiments on the separation and recovery of iron from a complex refractory iron ore by means of suspension magnetizing roasting and low-intensity magnetic separation processes. The purpose of the research is providing a new technology for effective utilization of refractory iron ore. Process parameters that affected the separation and recovery rate of iron were conducted and optimized, and the reaction process was analyzed by XRD and Fe mineral phase analysis."

Jan 1, 2018

By Xiqing Wu, Tao Yue

"Magnetic seeding co-agglomeration, i.e. adding magnetic seeds, organic depressant (such as the starch), and pre-magnetization for co-agglomeration, was applied in the reverse flotation for hematite ore slimes. Samples of the hematite ore slimes and the pure hematite fines were investigated by the co-agglomeration, respectively. Flotation tests suggest that the depressing effect of starch in the flotation was further enhanced with the addition of magnetic seeds and the pre-magnetization. Following the laser size analysis and flotation tests, TOC adsorption analysis, VSM, surface charge measurement, AFM, FTIR study, and SEM imaging have been utilized to understand the depressing mechanism. Based on the results it was demonstrated that with the addition of magnetic seeds and the low field pre-magnetization, the adsorption of starch onto hematite minerals was strengthened through the magnetic seeding co-agglomeration. The co-agglomeration improved the flotation performance by introducing the magnetic interactions and acting the bridging adsorption of starch between fine hematite and magnetic seeds in a suspension, and then resulting in an intensified coverage of the starch onto hematite particles and positive action in the coagglomeration under the pre-magnetization.INTRODUCTIONFlotation is undoubtedly the most important and versatile mineral processing technique, and both its use and application are continually being expanded to treat greater tonnages and to cover new area. However, its influence was limited to a relatively narrow particle size range of 5–300 µm (Wills and Napier-Munn, 2006). The main reason behind this limitation lies in that fine particles have high specific surface area, so need relatively high dosage of reagents (collectors or depressants), and exhibit poor flotation performance while intermediate or properly-sized particles produce high flotation kinetics and need low consumption of reagents. In order to increase the recovery of fine particles, quite a few of flotation techniques have been investigated. Most of them are based on particle aggregation, namely, by enlarging the apparent particle size, such as carrier flotation (Valderrama and Rubio, 1998; Zhu et al., 2009), shear flocculation (Duzyola and Ozkan, 2010; Yin et al., 2011), selective polymer flocculation (Rubio et al., 2007; Song et al., 2012; Ng et al., 2015), oil agglomeration (Laskowski and Lopez- Vladivieso, 2004; Forbes, 2011), temperature responsive polymer flocculation flotation (Forbes et al, 2011), and etc. However, these techniques above-mentioned are mainly studied for the direct flotation of fine minerals, and most of these techniques have not found applications for iron ore slimes especially recovered by the reverse cationic or anionic flotation."

Jan 1, 2018

By Janne Kytökari

Controlling a wide range of minerals processes with single control system is an ordinary way to operate in mines all over the world these days. However the potential of these systems is not yet fully recognized nor utilized. The key issue is to manage the information in a way that enables automating the day-to-day tasks, quality control and safety functions. At the same time it provides means for optimization and constant improvement of processes creating a working environment where the system helps employees to do their key tasks instead of searching, modifying, and transmitting the huge number of information arising every day. The distribution of control system nodes enables the other processes to run heedless of a problem occurring in one of the sub-processes. Also the control room can be in remote location such as in large city removing the need to travel substantially long distances to plant sites every day. When all essential information is brought to the same place there is less risk for a mishap to happen due to information breaks that are often the cause of them. One of the biggest single reasons that result in production losses are break downs of machinery usually caused by normal wear, misuse, incorrect utilization rate etc. For this reason it is important to measure the condition of machines using vibration measurement and diagnostics. By moving from failure or time-based maintenance towards predictive or performance maintenance generates eventually a steady and predictable process but also results in significant long term savings. The mineral process at Talvivaara mine is based on bioheapleaching, whereby metals are leached from ore as a result of bacterial action. Bioleaching is a fairly new technology used in metals recovery. Therefore it is important for the mine to collect and analyze data from different stages of the minerals process. Talvivaara mine?s Metso DNA system has integrated machine condition monitoring and information management. These are not only necessary but also crucial in environmental conditions where the outside temperature can drop below -35°C, where ice and snow dominate the landscape and impact the equipment for four months a year and where distances between equipment can be up to 7.5 kilometers. Keywords: DCS, analyzer, machine condition monitoring, automation, remote communications, optimization, mining, metso DNA, Talvivaara

Sep 1, 2012

By Alex Joseph

A tertiary amine containing polyamine in its back bone was grafted to exfoliated graphite oxide by means of a series of chemical reactions.The synthesized amine functionalized polyaniline grafted to exfoliated graphite oxide (EGAMPANI) was characterized using various techniques such as, FTIR, TGA, Raman, and X-Ray diffraction.The synthesized EGAMPANI was blended with carbon paste electrode, and used to study the response of Hg2+ in acetate buffer solution.Preliminary analysis showed that the anodic current intensity using the EGAMPANI modified electrode was higher during a potential sweep and 10-4 M concentration of mercury could be detected which could be improved to 10-6 M using anodic stripping voltammetric technique. Keywords: metal sensor, exfoliated graphite oxide, functionalization, polyaniline

Sep 1, 2012

By Bo Feng

The development of surface charge of serpentine mineral and implications for sulphide ?otation have been studied through flotation tests, sedimentation tests, zeta potential measurements and optical microscope photos. The results show that the serpentine mineral was positively charged at an extensive pH range, with an isoelectric point (IEP) of 11.9. The magnitude and sign of the pyrite particles were pH dependent and were negative for pH values above 2. At pH value 9, where ?otation of nickel sul?de ores is routinely performed, serpentine and pyrite particles attract through an electrostatic mechanism. Slime coatings of serpentine adhere to the surface of pyrite, reducing pyrite flotation recovery. The removal of magnesium ions from the serpentine surface by acid leaching results in a decrease of serpentine IEP and eliminates the adverse effect of serpentine on pyrite flotation. Therefore, it has been clearly established that the surface charge value developed in the serpentine/aqueous electrical interface is a function of the serpentine surface incongruently dissolution. As a result of hydroxyl dissolution, the magnesium ions are left in serpentine surface, which is responsible for serpentine surface charge. The methods, which can remove magnesium ions from serpentine surface, can be used to eliminate the adverse effect of serpentine on pyrite flotation.

Sep 1, 2012

By Aidan Giblett, Karen McCaffery, Robert Dunne

"A worldwide decline in competency levels of practicing metallurgists over recent decades has become clearly evident and is a common topic of discussion among senior practitioners and professional associations. The associated impacts on the industry are material and include operational inefficiencies, missed optimisation opportunities and suboptimal new plant designs. There are many contributing factors to this condition. Decrease in competency is particularly evident both in regions where imbalance between supply and demand has led to a general reduction in experience levels for comparable roles over time and in emerging regions where a rapid rise in demand for practitioners has occurred in conjunction with rapid economic development and industrialization. The context, depth and breadth of education curricula and levels vary with location such that solutions to the technical competency dilemma may need to be developed specifically for each region with these influences in mind. Delivering, demonstrating and maintaining competencies are a critical requirement of undergraduate training and ongoing professional development. Other factors such as generational and cultural characteristics and expectations, political influences, role requirements and employment reward and recognition systems all play a critical role in determining if core competencies can be effectively developed, applied and subsequently maintained. This paper reviews factors impacting and some common approaches to competency development. The authors’ experiences in the management of professional development efforts within the global industry are reviewed and a blueprint proposed to address industry requirements in this area."

Jan 1, 2014

By Osvaldo A. Bascur

One of the most vigorous of the continuous improvement methodologies is Six Sigma. While usually associated with improving manufacturing and product quality, leading manufacturers are using it to improve their extended supply chain and logistics capabilities. At the same time they are improving reliability, some companies have cut hundreds of millions of dollars of fat out of their supply chain. Mine to Mill optimization is a transformation of culture from processing tons to processing a quality feed size distribution which reduces the overall operational costs and add the highest value to the mine. This is not a constant endeavor. As such, a dynamic performance monitoring and diagnosis is necessary. We will review a systemic way to performance improvements and avoiding metal losses from the blast to the metals. We show the requirements of using raw data to analysis the data to define operational maps which provide assistance to run the mine and mill. A case study is provided with the mine and mill data was integrated combining process control and quality information resulting in reduction of water and energy consumption while improving the overall value of the mine. The results of reengineering the current system with this SIX SIGMA Strategy had the following results: an increase of ore milling: 4.6% decrease of mil power: 3.9%, decrease of fresh water consumption: 6.8%, with a total of net profits: US$ 31.8 million, the PI System infrastructure contribution: US$ 7.95 million. These estimates were for the period 2009/04/04 to 2009/12/31.

Sep 1, 2012

By S. Z. Shafaei

An experimental investigation has been carried out using a laboratory scale Denver flotation cell. For evaluation of cokeable coal of Alborze Sharghi coal washing plant, the full factorial method was used to statistically design and analyse the experiments. The 2 factorial interaction model were developed for combustible recovery and ash content as response and diesel dosage, conditioning time, feed percent solids and rotor speed as factors. Model validation and residual analysis were con-ducted and results indicated that the fitness, predictability power and residual distributions of models were good. The effect of parameters and interactions were examined and it has been demonstrated that rotor speed, solid percent and interaction between diesel dosage and solid percent were more important terms of all responses. A product with approximately 78% combustible recovery and 10% ash content was obtained at 4000gr/ton diesel fuel oil (high level), 30 sec conditioning time (low level), feed percent solids of 15% (low level) and 800 rpm rotor speed in appropriate condition.

Jan 1, 2014

By Yang Xiao, Zhang Yimin, Bao Shenxu, Liu Chun

Stone coal is a unique vanadium-bearing resource in China. Many techniques, such as salt roasting-water leaching, blank roasting-acid leaching, direct acid leaching etc. have been developed for vanadium extraction from stone coal. The vanadium leaching rate can reach 74.9% for stone coal from Jiangxi, but only about 27% of vanadium is leached for Hubei ore by applying salt roasting-water leaching technique. This paper investigats the vanadium occurrence in stone coal by microscope observation and electron probe, and compares the minerals components of stone coal from Jiangxi and Hubei. Although most vanadium exist as an isomorphism by replacing Al(III) from dioctahedral structure in mica group minerals in stone coal from two regions, the free vanadium is remarkably abundant in Jiangxi stone coal than in Hubei stone coal, which results the fact that vandium is relatively readily extracted from former. Moreover, the content of calcite in Hubei stone coal is much higher than that in Jiangxi stone coal. Calcium can react with V2O5 to form water insoluble calcium vanadates during roasting and this may be the reasone why the water leaching rate of vanadium is low for Hubei ore. Acid leaching is more beneficial to the vanadium leaching but other extra methods, such as adding aid-leaching agent and/or increasing acid concentration is need for the ore where vanadium is embeded firmly. This study can effectively guide the selection of vanadium extraction techniques for stone coal from different regions.

Jan 1, 2014

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

Jan 1, 2014

By Jiongtian Liu, Guixia Fan, Caom Yijun

A cyclonic-static micro bubble flotation column (FCSMC) is an effective separation device for fine grain treatment. The separation of fine ilmenite by FCSMC was explored in this work. The influence of reagents dosage (regulator, collector and auxiliary collector), pulp density, circulation pressure and aeration quantity on TiO2grade and recovery wasinvestigated.The optimal conditions of a rougher are follows: pulp density 45%, pH 5.0, MOH collector dosage 2800 g/t, diesel oil dosage 700 g/t, circulationpressure 0.19 MPa, aeration quantity 0.8 m3/(m2•min). The optimal conditions of a cleaner are follows: pH 4.0, circulation pressures 0.16 MPa, and aeration quantity 0.5 m3/(m2•min).A pilot plant continuous test with a rougher-cleaner by FCSMC for 72 hours was proceeded under the optimum conditions. Compared with industrial flotation machines, the concentrate grade of FCSMC is 48.11% with an improvement of 1.08 percentagepoints, while the recovery is 82.36% with 13.64 percentagepoints increment. Moreover, the flowsheet is simplified from six parts (a rougher-two scavenger-three cleaner) in flotation machines to two parts (a rougher-cleaner) in FCSMC. Proofs were also provided by the analysis of the by-size grade and recovery of concentrate.Results show the FCSMC is an effective separation device to recover -74 µm size fraction.

Jan 1, 2014

By S. Gaydardzhiev

Initial experiments towards preparation of hollow ceramic microtubes by dip-coating of fibrous plants with water based alumina gel-casting slurries using hemp and coconut fibres as templates have been done. It has been found that the wettability of fibres and accordingly the stability of the developed ceramic layer on their surface during slurry gelation varied significantly within the different fibre types. Good correlation between the diameters of the template fibres and the resulting channels has been found at the level of solids loadings used, 31 %. Hemp fibres used as bundles have led to formation of multi channel patterns while the coconut fibres-templated process resulted in uniform monochannel materials. The micro tubes have show good mechanical handling.

Jan 1, 2014

By Silvia Serranti, Giuseppe Bonifazi, Roberta Palmieri

The possibility to develop an efficient recovery and reuse of concrete materials from Demolition Waste (DW) represents one of the main targets applied to end-of-life constructions dismantling/recycling. The need to recycle end-of life concrete materials is strongly increasing in these last years for several reasons: i) the decrease of steady supplies of good quality natural aggregates, ii) the need to secure ample supplies of concrete aggregates to the construction industry and, finally, iii) the environmental constraints limiting the DW wastes disposal. The fulfilment of these goals produces several benefits, that is: i) a reduction of new resources consumption, ii) a strong reduction of the costs linked to transport and energy production, iii) the possibility to utilize materials, otherwise lost (e.g. land filled), iv) land preservation and, finally, v) the reduction of the environmental impact of new exploitation activities. A lot of efforts have been addressed to develop, set-up and apply innovative technologies to maximize DW conversion into useful secondary raw materials. The possibility to utilize efficient, reliable and low cost analytical tools to perform detection/control actions: i) to assess concrete characteristics, before demolition, and ii) to detect the presence of contaminants in coarse aggregates (e.g. bricks, gypsum, steel, glass, plastics, wood, etc.) represent the key issues to fulfil in order to develop innovative process/control actions/procedures inside the DW sector. In this paper a new technology, based on HyperSpectral Imaging (HSI) sensors is investigated to develop suitable and low cost strategies finalised to define and implement innovative smart detection engines for sorting and/or DW flow stream quality control, addressed to perform recovered materials and/or products certification. The proposed sensing architecture is fast, accurate, affordable and it can strongly contribute to bring down the economic threshold above which recycling is cost efficient.

Jan 1, 2014